Eff orts that nourish a critical discourse—be they formal, informal, local, transnational, or global—need to be extended into the heart of society in order to avoid limiting the discourse to a handful of intellectuals in the academic realm. A thorough understanding of the historical dimension, so the belief goes, will ground and substantially enhance people's unique entrepreneuring capabilities for the benefi t of their societies. Research endeavors could start at the continental, national, or ethnic level, for example, by asking, What are the historical roots of entrepreneurial behavior in Kenya and other African economies? How have organizing concepts evolved over time within and across ethnic lines in a particular geographical cluster in Africa ? What were the mechanisms behind the development , proliferation , and translation of inventions and innovations within and across ethnic lines ? Behind these and many other questions lies a wealth of wisdom—a treasure that needs to be lifted for the benefi t of all.

## **Pan-Africanism in Business**

 In our conversation with Ken Njoroge, he expanded on his entrepreneurial journey and said, "I consider myself generally ambitious and motivated. Otherwise, why aim for a USD1 billion Pan-African company?" It seems self-evident today that Kenyan enterprises venture fi rst into regional and Pan-African markets before even considering leaving the continent's boundaries. Th e development and respective benefi ts of new technologies from Africa are thus deployed fi rst in, and for the benefi t of, other African economies—demonstrating that entrepreneuring does not stop within national borders but only within the "borders" of the technology (Beckman et al. 2012 ), continuing onward to scale and to outgrow its own market. A step toward increased Pan-African trade, collaboration and knowledge exchange driven by the private sector 3 is becoming a vibrant reality, a development that was not obvious two decades ago when Mazrui ( 1993 ) wrote that "uniting against the foreign oppressor was one thing; uniting for internal development was another. Th e earlier part of this period of history [the twentieth century] has demonstrated that Africans are eff ective when they unite for liberation. Th e later part of this era demonstrated that Africans are fi nding it hard to unite for political and economic development." Achielle Mbembe ( 2002 ) continued this line of thought, arguing that eff orts to "re-invent a beingtogether" were largely relegated to peripheral importance, muting action that would focus on a renegotiation of the social bond among Africans who had been "corrupted by commercial relationships (the sale of human beings) and the violence of endless wars."

 It is against this background that Pan-African initiatives require particular attention. Osiakwan raised, in his chapter, awareness of developments at the Pan-African level by outlining similar trends that are aff ecting Kenya, Côte d'Ivoire, Nigeria, Ghana, and South Africa—and

3 Th e trend in intra-African economic exchange is not confi ned to technology enterprises but also applies to banking, fast-moving consuming goods, and the hospitality industry, among others.

thus the evolution of a Pan-African knowledge economy. With his designation of the "KINGS" economies, Osiakwan introduced a sense of connectivity and a shared future at a Pan-African level that is likely to intensify as time passes. In particular, Pan-African conferences, workshops, Internet platforms, and organizations create a new dimension of entrepreneuring, one that works to overcome and remove constraints at the transnational level. Tony Elumelu, a Nigerian philanthropist, struck a similar chord with his eff orts to foster entrepreneurial excellence at a Pan-African scale and by crafting the neologism Africapitalism, a management concept that seeks to remoralize capitalism in Africa by putting it to work for society and by thrusting African economies onto an equal footing with those of the rest of the world (Amaeshi and Idemudia 2015 ; Elumelu 2011 ).

 Th ese remarkable economic, social, and cultural developments require further academic inquiry to understand their full magnitude and potential. Raising awareness of these trends may also spill over into the policy arena and accelerate and strengthen a Pan-African agenda that reaps benefi ts for all African citizens and creates substantial economic power. Regional and Pan-African integration will provide further fuel to the already ongoing transnational entrepreneurial actions.

## **Africa's Response to Grand Global Challenges**

 Catching up, reaching an equal level of socio-economic development, or leapfrogging technologies are some of the buzzwords that mingle in the current discourses on societal evolution strategies in Africa. Yet increased global migration, rising global economic inequality, a crippled world economy, global hunger and severe malnutrition, the eff ects of a deteriorating climate, and the crumbling façade of capitalism are just a few of the daunting global challenges that will require a new frame of reference for the current—and the next—generation of entrepreneurs in Africa. Th e task, therefore, becomes not only to develop African societies and to "catch up with the rest," but rather to place grand global challenges at the center of entrepreneurial inquiry in innovation processes, asking, What are the responses from Africa to these grand global challenges?

 Th e current innovation scenery among multinational companies, for example, is best encapsulated by the term "reverse innovation" (Govindarajan and Trimble 2012 )—"developing ideas in an emerging market and coaxing them to fl ow uphill to Western markets" (Govindarajan 2012 )—attesting a deep-seated mindset stuck in an old paradigm that sees innovation creation as a one way pipe leading "downhill" from the Global North to the Global South. Going against the fl ow then requires special engineering capabilities. However, innovation development on the globe today is much rather circular and dynamic in nature which makes countries of the Global South just as much a part of the global quest for innovations and inventions then the Global North. Indeed, we are all in it together.

 Take Google X, for example, a research and development initiative by the company Alphabet (formerly known as Google), that seeks to grow a global community of radical innovators and inventors to tackle the world's biggest challenges. 4 In this worldview, the correct problem defi nition and solution can come from anywhere in the world, still, be mindful as to who is setting the terms for innovation and invention. Initiatives like this one, though still scarce, help create a global mindset among their members in which entrepreneuring means to overcome and remove constraints at a global rather than a local or transnational level. Arguably, truly path breaking inventions and innovations will come from a mindset in which solutions to grand global problems are just as important as local ones. And in fact, both approaches can be synergistic. Th ere is a demand for similar initiatives from Africa.

 Entrepreneuring around grand global challenges helps realize the potential to defi ne a global agenda from an African perspective, with far-reaching implications for prevailing global power structures and the potential to propel global society forward in the quest for path breaking solutions. Indeed, the current—and the coming—generations of entrepreneurs are part of an exciting time, a time that in the years ahead will no doubt continue to unveil ever more of Africa's unique entrepreneurial revolution.

To be continued….

4 See https://www.solveforx.com

## **References**

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## **Index**

#### **A**

 Acumen, 263, 274 address, lack of physical, 124 AFB, 68, 118 Africa . *See also* Kenya, Ivory Coast, Nigeria, Ghana and South Africa ('KINGS') digital economy, 5, 55–93 doing business in, 425, 431, 440 economic growth, 5, 59, 60, 429, 461, 462 entrepreneurship in, 2, 10, 266, 332–3, 403–17 Foreign direct investment (FDI), 429 government procurement, 365 ICT in, 63, 64, 66, 133, 134 importance of history to digital future, 29 lack of quality middle management, 406

 leadership models, 57, 89 mindsets for development, 85–93 mobile phones growth, 57, 86 numbers in agriculture, 431 parallel entrepreneurship in, 10, 403–17 population, 58, 220, 407, 468 recommendations for capturing innovation wave, 77 reimagining education in, 135, 142–5 technology entrepreneurship revolution, 266, 475 unemployment, 2, 364, 407 venture capital *see* (venture capital, in East Africa) Western view of, 19–21 African Center for Open Governance (Africog), 352, 353 African Development Bank, 69, 415 African Leadership Academy, 91

© Th e Author(s) 2017 **487** B. Ndemo, T. Weiss (eds.), *Digital Kenya*, DOI 10.1057/978-1-137-57878-5

 African Management Initiative, 414 African Regional Centre for Computing, 30, 32n1, 33, 37, 40 Africa Online, 15, 17, 33, 37 Africog . *See* African Center for Open Governance (Africog) Afroes, 85–8, 91, 92 aggregators and distributors, as market enablers, 101–2 agriculture, 121, 171, 178, 179, 181–4, 220, 221, 270, 298, 359, 431, 468 AirBnB, 104, 105, 129, 137, 145, 149 Airshop, 70 Airtel, 57, 61–3, 116, 188 Akinboro, Bolaji, 68, 395 AkiraChix, 46, 48, 259–64, 317, 466 Akunga, Conrad, 47, 52, 331 about, 331 conversation with, 332–6 Alai, Robert, 200 Alcatel, 351, 352 Alcohol delivery, 426–7 Al-Shabaab, 199–200, 207 Amazon, 103–5, 109, 111, 112, 147, 369 Angel Fair Africa, 76 Angel investors, 51, 73, 239, 247, 274, 422, 457 ANSUT . *See* National Agency of Universal Service in Telecommunication/ICT (ANSUT) Apenteng, Ernest, 73 ARTCI . *See* Autorité de Régulation des Télécommunications/ Tic de Côte d'Ivoire (ARTCI)

 Ascent Capital, 435, 440 Association for Progressive Communications (APC), 29, 32 Autorité de Régulation des Télécommunications/ Tic de Côte d'Ivoire (ARTCI), 64

#### **B**

 Bamba mobile airtime cards, 21 bandwidths, growth in, 28, 30, 32–4, 38, 62, 169, 233 bank accounts, access to, 3 banks, 61, 64, 69, 101, 103, 113, 120, 150, 157–60, 220, 221, 273, 355, 378, 384, 397, 409, 424, 439, 471 Barclays Bank, 439 Barnwell, Nikolai, 303, 318, 319 Berthod, Frank, 69 Bishop Magua Center, Nairobi, 233 bitcoin, 121, 155–8, 160, 233, 470, 471 BitPesa, 3, 155–61, 233, 471 blogging, 46, 191–3, 285 Bluechip Technologies, 71 books, as technology, 143, 144 Botswana, and Kenyan social media, 204 Bram, Alex, 73 Brave Venture Labs, 291–4 BRCK, 3, 45, 48, 49, 463 Bridge International Academies, 147 Buch, Kresten, 315–17, 319 business doing in Africa, 426, 431, 440 doing in Kenya, 9–11, 268, 423

 perceptions of skills needed for, 431 registration problems for entrepreneurs, 241, 250, 366 business-process-outsourcing (BPO), 165, 168–75, 356 BusyInternet, 56, 72

#### **C**

 CAK . *See* Communications Authority of Kenya (CAK) (formerly Communications Commission of Kenya) Cape Town, South Africa, 55, 75, 76, 120, 316 C Corporations, Delaware, 454, 455 Cellulant, 68, 113, 114, 120, 395, 396, 400–2 Celtel, 57, 187 Central Bank of Kenya, 355 chamas, 445 change creation, 463, 471, 478 . *See also* creation of newness 'Cheetah Generation,' African youth as the, 58 Chinese technology in Africa, 190 christianity, impact of in Africa, 19 civil society organizations (CSOs) Internet advocacy, 40 role in evolution of Internet, 38–42 use of social media, 199, 202 ClaimSync, 72 cluster theory, and entrepreneurship ecosystems, 229, 232 CNN, coverage of Kenyan aff airs, 203, 206

 Colaço, Jessica about, 291–2 conversation with, 292–302 collectivism balance with individualism, 467 importance of outlook based on, 21 mindsets for, 21–3 colonialism, in Africa, 19, 20, 381n12 Communications Authority of Kenya (CAK) (formerly Communications Commission of Kenya), 28, 61, 64, 271 communities of practice, need for, 77, 240 company evaluation, "bricks and mortar" *vs.* "strategic value," 379–80 competition among ISPs, 33, 34 among telecommunication services, 34, 62, 251 need for enabling environment, 77 competitiveness, Kenya's ranking, 99 computer games, 86, 91 computers number of, 38 training in using, 16, 167 concurrent entrepreneurship . *See*  parallel entrepreneurship confl icts, in Africa, 372–3 *connected world: greasing the wheels of the Internet economy, Th e* (Boston Consulting Group), 100

 connectivity advancements in Kenya, 4, 232, 233 and business-processoutsourcing, 15 challenges in early days, 32, 34, 37 fastest African Internet in Kenya, 67, 169 key to entrepreneurial ecosystem, 233 need for policy, 340–1 and regulation, 33–4 and social media, 7, 187–90, 203 context-specifi c research, need for, 229, 475 contract farming, 182 contracts, relations *vs.* , 377–8 corporations, potential for venture capital, 445 corruption in Africa, 406, 416 and digitization of government services, 121, 222 need for technology to combat, 223 and Posta land development, 356–8 in telecommunications sector, 340 and venture capital funding, 440 costs impediment to venture capital funding, 440 for Internet use, 37 to ISPs, 37 minimising of venture capital fund, 436 for venture capital investors, 434 cost Sharing system, 16 craft Silicon, 69

 craigslist, 106 creation of newness, 463, 470–3 . *See also* change creation credibility enhancers, as market enablers, 101 credit rating bureaus, as market enablers, 101 criminal entrepreneurship, 477 critical mass, importance of, 247–8 critical refl ection, on entrepreneurship, 382n15, 463, 467–70 CSOs . *See* civil society organizations (CSOs) culture . *See* organizational culture customer-premises equipment, market for, 36 Cyber Cafés, 7, 187–210 'Cyber wars,' in Kenya, 204

#### **D**

 data, lack of ICT, 175 Davies, Mark, 56, 72 Demo Africa, 76 developing countries impact of mobile and broadband, 58 mindset of aid-givers to, 89 dial-up lines, number of, 37 Digital Afrique Telecom, 70 Digital Divide Data (DDD) Kenya, 164–73 digital economy, Africa, 5, 55–78 digital entrepreneurship . *See*  entrepreneurship digital lines, number of, 37 Digital Nyika, 22, 470 digital platforms . *See* marketenabling digital platforms

 digital technology . *See* information and communications technology (ICT) disruptive innovation impact of, 31–40 importance of, 5, 40–2 synonym for newness, 470–3 theory of, 27–9 distributors, as market enablers, 101 doctors, online protest movement, 198 *Doing Business* report (2015) (World Bank), 99 domain names, number of, 37 donor organizations, grants from, 303, 304 Doshi, Ritesh about, 422 conversation with, 422–7 Drayson, Timbo about, 123 conversation with, 123–31 DreamOval, 74 Dropifi , 72 Dror's general systems theory framework . *See* general systems theory drought, online fundraising campaign following, 196–7 Duma Works, 116, 119

#### **E**

 EAIA . *See* East African Internet Association (EAIA) East Africa Marine System (TEAMS) (fi bre optic cable) . *See* Th e East Africa Marine System (TEAMS) fi bre optic cable

 East African Community (EAC), 431 East African Internet Association (EAIA), 30 East African Internet Exchange, 37 East Africa Submarine Cable System, 16, 352 East Legon, Ghana, 73 Eaton, Carey, 388n19 EatOut, 114, 117, 421, 422, 424–6 eBay, 102, 104, 108, 111, 384, 475 Econet Wireless, 57, 187 economic growth in Africa, 60, 461, 462 challenges in Kenya, 98 of the 'KINGS,' 59, 60 linked with digital transformation, 5 shrinking in Kenya, 16 education importance of curiosity, 333, 334 importance of the middleman, 139–2 open source movement, 135, 137–9, 145 opportunities for reimagining, 135, 142–5, 147 in technology, 19, 52, 73 technology-driven, 145–50, 269 traditional, 142–5 e-friction index . *See Connected world: greasing the wheels of the Internet economy, Th e* (Boston Consulting Group) 88mph (now Nairobi Garage), 61, 75, 304–6, 309, 313–23, 344 Elbagir, Nima, 205

 elections, and social media in Kenya, 199 electricity supply, 171, 175 Elimu, 68 email, 3, 28, 29, 31–4, 37, 39, 41, 188–90, 192, 275, 292 emerging markets barriers to entrepreneurship, 267–8 institutional voids, 99 lack of market enablers, 101–3 employment lack of opportunities for, 238 opportunities in agriculture, 181 percentage of Kenyans in, 2 technology for generating, 145–50 Enhanced Total Access Communications System, 32 Entrepreneurial Solutions Partners, 69 entrepreneurship . *See also* parallel entrepreneurship; technology entrepreneurship in Africa, 24, 234, 332, 404–6 around global challenges, 482 barriers to in emerging markets, 8, 265–302 characteristics of, 59, 178, 295, 371 creation of newness as, 470–3 criminal, 477 cultural norms around, 230, 235–7, 246 dark sides of, 476–8 driving venture capital in East Africa, 442 fundamentals for success, 401–2

 and government, 365, 366 hustling *vs.* single-mindedness, 373–5, 389 importance of location, 473–6 importance of mindsets, 464–70 new forms of, 266, 267, 269–70, 283, 284 notion of, 140 relevant policy, 241 social, 6, 85–6, 164–6, 177, 269, 463 ( *see also* Digital Divide Data (DDD) Kenya) concept of, 164–5 impact sourcing, 165 for society, 11, 461–82 strategies for, 375–7 entrepreneurship ecosystems Kenya's ranking for, 98 in 'KINGS' countries, 59–61, 78 in resource-scarce contexts, 7, 227–53 advancements in Kenya, 233 barriers and enablers, 228, 230, 234–7, 242–4 development trajectory, 244–8 need for future research, 252–3 recommendations for establishing, 248–52 research methods, 234–5 theoretical frameworks, 228–33 Equitel, 61 Esoko, 73 Ethics and Anti-Corruption Commission, 352, 357 Etisalat, 61, 62, 350, 351 evergreen funds, 444, 448 expressPay, 120, 121

#### **F**

 Facebook, 129, 147, 188–90, 192, 196, 199, 201, 209, 365, 456, 470

 failure mindset for preparing for, 385 need for more research into, 477 part of entrepreneur's journey, 369 family members, provision for as cultural characteristic, 237 famine, online fundraising campaign following, 196 Farmerline, 74, 773 farming, 180–3, 186, 409, 468 . *See also* agriculture fast-moving consumer goods (FMCG) supply chain, 117 fi ber-optic cables . *See also* Th e East Africa Marine System (TEAMS) fi bre optic cable in Africa, 15, 17 bringing broadband to the masses, 58 government investment in, 39 need for policy, 346, 349, 353 superceding coaxial cables, 31 FidoNet technology, 28, 31 fi nance . *See* funding; investment; venture capital fi rst-generation (1G) systems, 31 foreign aid, 49–51, 381, 385, 387, 464 foreign direct investment (FDI), Africa, 429, 430 foresight Ventures, 411 FORM-Net Africa, 15, 17, 33, 37 for-profi t organizations, 305, 309–14, 321 . *See also*  88mph; organizational cultural hybirds

 fourth-generation (4G) systems, 31 funding . *See also* investment; venture capital from angel investors, 51, 274 for entrepreneurship ecosystems, 231, 233, 239, 240, 243 from grants, 304, 306, 317, 318, 321, 324 of Internet development, 30 lack of as key barrier, 242 from NGOs, 50 for parallel entrepreneurship, 415–17 perceptions of availability, 266

#### **G**

 GamesforChange, 91 gender gap, in use of the Internet, 42 General Packet Radio Service, 39, 187 general systems theory, 341, 347–8, 359, 361 geographical coverage, of Internet, 39–40 Ghana economic growth, 60 information and communications technology (ICT), 72–4 market-enabling digital platforms, 113, 120 mobile market, 62 Parallel entrepreneurship in, 405 supportive government policies, 67 technology infrastructure, 62, 63 Ghana Angel Investor Network, 73 Ghana Cyber City, 73 Ghana New Ventures Competition, 56, 72

 Ghana Telecom, 63 Gichuru, Sam, 207, 304 Githongo, John, 198 Githuku-Shongwe, Anne about, 85–6 conversation with, 86–93 on importance of mindset, 464 Gitonga, Jimmy, 388, 470 about, 13–14 conversation with, 14–23 Glo, 57, 62, 63 global challenges, Africa's response to, 481–2 *Global Competitiveness report 2015– 2016* , Th e (World Economic Forum), 99 Global Entrepreneurship Index (GEI), 100 Global Entrepreneurship Summit (GES), 66, 67, 206–8, 263–4 globalization, in Africa, 19 Google, 3, 38, 47, 52, 53, 63, 67, 105, 112, 123, 124, 129, 172, 189, 190, 193, 222, 300, 304, 308, 314, 323, 335, 363–5, 469, 482 government digitization of services, 468 early attitude to Internet, 28–9, 42 entrepreneurs' reluctance to engage with, 364–5 and parallel entrepreneurship, 413–14 policies and entrepreneurship, 231, 241, 343, 344 role of in technology industry, 49, 262

 subsidized loans, 443, 448 support for Internet evolution, 40–1 supportive policies for 'KINGS,' 63–5, 78 ( *see also* policy development and implementation) grant funding, 8, 50, 303, 304, 306, 317, 318, 321, 324, 387 Green Dreams, 177, 179–80 GreenNet, 31, 32 GRIDCo, 63 Grovest, 75 Growth Economy Venture Challenge, 332

#### **H**

 Hanga Umurimo Fund, 443 HealthNet, 35 hedging, as business strategy in Africa, 408–9, 411 Hersman, Erik about, 45–6 conversation with, 46–54 and iHub, 291–3, 315 as role model, 388 and TEAMS, 354 and Ushahidi, 193 high-frequency radio, use for telecommunications, 31, 35 history, importance of African, 20, 478–80 Hivos Foundation, 304, 314, 323 Hotels.ng, 71 Huawei, 189, 190, 268 human capital contracts, 412, 413 development, 52–3, 249

 for entrepreneurial ecosystem, 227, 230, 231, 242, 247–9 lack of quality middle management, 406 recruitment, 148, 167, 228, 411 Hunja, Robert, 350, 351 hustling . *See also* parallel entrepreneurship evidence of entrepreneurship, 442 fi nancing, 366 need for more research into, 446 *vs.* single-mindedness, 373–5 stumbling block to foreign investors, 446 views on, 423 hybridization, 300, 304, 308, 318, 322 hydroponics, 179, 180

#### **I**

 IBM, 52, 268, 304, 314, 323 ICASA . *See* Independent Communications Authority of South Africa (ICASA) iCow, 177, 178, 183–6 ICT . *See* information and communications technology (ICT) ICT Authority, 170, 173, 240 iHub case study, 313–21 collaboration at, 292 formation, 48 government intervention in, 344 and importance of location, 473 as non-profi t organization, 293 as organizational cultural hybrid, 305, 306, 309, 313, 315, 317, 320

 pioneer of co-working space, 17, 263 and TEAMS, 354 iLab, 344, 457 Impact Hub Accra, 73 impact sourcing, 6, 164–6, 175 incubators, 1, 8, 60, 66, 70–3, 75, 230, 234, 236, 237, 239, 246, 250, 304, 305, 313–16, 319, 322, 324, 326, 389, 456 Independent Communications Authority of South Africa (ICASA), 64 India, 2, 15, 71, 171, 174, 293, 340, 415, 435 individualism, 21, 466, 467 Industrial Revolution, impact on Africa, 19, 21 industry events, in Africa, 14, 76 industry standards, need for established, 174, 175 informal sector, connections with parallel entrepreneurship, 415, 416 information access to via the Internet, 39 importance of digital, 144 need for more on ICT, 173 information analyzers and advisors, as market enablers, 101 information and communications technology (ICT) . *See also*  entrepreneurship ecosystems in Africa, 63, 64, 66 commissioning of products and services, 244–7, 249 commitment to, 17, 66 and eff ects of change, 469

 information (*cont*.) evolution of, 7, 29–31, 228 phases, 29–31 future in Africa, 20–1 impact of, 12 infrastructure, 2, 230, 233, 245, 248–9, 346, 359 policy development and implementation, 9, 342, 348, 354 policy implications, 358–60 potential for employment, 6 and social enterprises, 164 information asymmetries, in Nairobi, 285 infrastructure for entrepreneurial ecosystems, 59, 231, 233 inadequate in emerging markets, 268 in 'KINGS' countries, 65 need for policy, 341 need for reliable, 151, 175 need for strong local, 77 Innova Ltd, 331, 332, 335, 336 innovation recommendations for in Africa, 77 reverse, 482 innovation hubs . *See also* iHub in Nairobi, 271–4, 439 perceptions of funding for, 265 perceptions of investment for, 272 perceptions of skills needed for, 266, 275–7, 280, 282 interactive decision-making theory, 341, 343, 347–9, 358, 361 interest rates, 103, 267, 273, 366

 international stakeholders dissonance with local stakeholders, 237 and local stakeholders, 292 internet and BPO companies, 172 contribution to African GDP, 58 cultural icon, 195 diff usion and impact, 31–40 disrupting of real estate market, 106 evolution of, 30–1 fastest African connectivity in Kenya, 169 growth in use on mobile phones, 188 journey for Kenya, 5, 27–42 Kenya's ranking for constraints, 99 launch of full system, 30, 36 lessons from the evolution of the, 40–2 music on the, 190, 195 penetration rates, 233 reimagined distribution, 145 service off erings supporting the, 36–8 internet service providers (ISPs), 29, 31–4, 37–9, 398, 402 Interswitch, 72 Inuka Kenya Trust, 198 investment . *See also* foreign direct investment (FDI), Africa; funding; venture capital angel, 242, 249, 250 in East Africa, 432 for entrepreneurship ecosystem, 240, 242, 243, 245, 250

 lack of as key barrier, 242–4 need for best models, 468 and parallel entrepreneurship, 408, 417 perceptions of availability, 266 perceptions of skills, 266 returns on, 57 view on market boundaries, 279 Invisible Children campaign, 202 iROKOtv, 71, 72 ISPs . *See* internet service providers (ISPs) Israel, 343, 446, 448 Ivory Coast, 5, 56, 60–2, 64, 65, 69–70

#### **J**

 Johannesburg, South Africa, 75, 446 Jomo Kenyatta University of Agriculture and Technology, 270 Joseph, Michael, 352, 354–6 JuaKali, 259 Jumia, 71, 118 Jump Associates, 292, 293 Just a Band, 194, 196

#### **K**  Kacou, Eric, 69 Kagwe, Mutahi, 67, 339, 350, 353 Kahumbu Stephanou, Su about, 177–8 conversation with, 178–86 Kenya Bloggers Webring (KBW), 191 Kenya Bureau of Standards, 101, 171

 Kenya ICT Action Network (KICTANet), 3, 354, 359 Kenya ICT Authority (KICTA), 64, 67 Kenya Information and Communication Act (1999), 27, 28 Kenya Internet Exchange, 31, 38, 40 Kenya IT and Outsourcing Society (KITOS), 174 Kenya, Ivory Coast, Nigeria, Ghana and South Africa ('KINGS') . *See also*  Africa; Pan-Africanism, in business characteristics, 59 leading development of digital economy, 56 profi les, 65–76 *Kenya Law Reports* , 172 Kenyans on Twitter (KOT), 191, 193–5, 197, 199, 200, 202–5, 207, 303 Kenya Open Data Initiative, 3 Kenya Posts and Telecommunications Corporation (KP&TC), 27–9, 31–7 Kenyatta, Uhuru, 66, 204, 207, 208, 263–4 Kenyatta University, 168, 270 Kenya Vision 2030, 5, 93, 170, 175, 178, 471 Khan Academy, 146 Kibaki, Mwai, 9, 67, 339, 341, 347, 350, 353, 356 KICTA . *See* Kenya ICT Authority (KICTA)

 KICTANet . *See* Kenya ICT Action Network (KICTANet) Kilimani Project Foundation, 366 Kinyua, Joseph, 352, 355 Kirubi, Chris, 207, 403 Kisumu Municipal Council, 170 knowledge combined with technology, 6, 133 in farming, 181, 182, 468 and poor technology infrastructure, 38 production of, 462, 478 Kobia, David, 3, 192, 193 Kongo, Kingdom of, 18, 19 #Kony2012, 202–4 Konza Techno City, 68 Kopo Kopo, 68, 453, 454, 456, 458 KP&TC . *See* Kenya Posts and Telecommunications Corporation (KP&TC) Kuhustle, 116, 119 Kyalo, Victor, 66, 67

#### **L**

 Lagos Angel Network, 71 land development, and the policymaking process, 356–8 language, importance of, 52, 470 La Régionale, 69 La Société Nationale de Développement Informatique (SNDI), 64 last mile logistics, 427 leadership models, 57, 89 Leadpath, 61, 71 lean start-up, 127–9, 444, 448 learning . *See* education

 leased lines, 29, 30, 33, 35, 37 legal structures, 408, 417 Leti Arts, 72 libraries, 6, 135, 143, 144, 333 LION2 undersea cable, 62, 233 local stakeholders, 252 location, as comparative advantage, 463, 473–6 Lumumba, P.L.O., 357 Lyon, Ben about, 453 conversation with, 454–9

#### **M**

 Macharia, Mike, 52, 68, 388 Maddox, Tony, 208 Makmende meme (Internet cultural icon), 194–6 Mall for Africa, 71 Mama Mikes, 69 management lack of, 406–7 of parallel businesses, 409 market-enabling digital platforms characteristics, 103–5 concept of, 98 emerging in Kenya, 112–19 impact of, 119–21 in Northern Hemisphere economies, 105–12 market research organizations, 101 markets development of for entrepreneurial ecosystem, 231 enablers, 101–3, 107, 114 lack of as key barrier, 242–4 lack of for new products and services, 267, 268

 need for domestic, 174 need for venture-friendly, 230, 241–2 opportunities for, 5–7, 384, 426–7 perceptions of right, 266 voids, 98–101 Mashada.com, 192 Masiyiwa, Strive, 57 Massive Open Online Courses (MOOCs), 146, 150 McKenzie, David, 194, 203, 204 Medics, online protest movement, 198 Meltwater Entrepreneurial School of Technology, 72, 73 Meshak, Alloys, 118 M-Farm, 68, 317 microfi nance institutions (MFIs), and mobile money, 454 Microsoft, 16, 67, 87, 103, 314, 323, 400 middlemen, importance in education, 139–41, 156 mindsets . *See also* worldviews changing, 85–93 concept of, 371n4 importance of, 417–20 for managing worldviews, 382–6 and technology entrepreneurship, 10, 242 within worldviews, 274 mistrust . *See* trust Mitra, Sugata, 297 M-Kopa, 52, 233 mobile computer games, 86, 91 mobile money . *See also* Cellulant; Kopo Kopo; M-Pesa and agriculture, 182 creating fi nancial inclusion, 59, 67

 need for, 184 penetration rates, 60, 233 for primary education, 147 mobile phones cellular, 32, 187 corruption in sector, 340 dominance of global technology companies, 268 growth of use, 58 Internet use, 189 numbers in Africa, 64 numbers in Kenya, 18, 171, 175, 240 numbers in Nigeria, 413 penetration rates, 60, 232 shift from cyber cafés to, 7, 187–210 MOOCs . *See* Massive Open Online Courses (MOOCs) Moov, 61, 62 Moraba computer game, 86 Mozilla Open Badges system, 149 M-Pesa creating fi nancial inclusion, 59, 67 and fi nancial freedom, 3 impact of, 472 importance of collaboration, 245 and Kopo Kopo, 453 launch of, 17, 64, 113 percentage of transaction fl ow, 67 and policy development, 9, 358 reduction in transaction costs, 134 value of transactions, 102, 116, 354–6 MTN, 57, 61–3 Mucheru, Joseph, 66, 67, 222, 388 Muli, Daniel, 194

 multiculturalism, 8, 305, 306, 321, 324 . *See also* organizational cultural hybirds multilinks, 62, 63 music, on the Internet, 190, 194, 195 Musk, Elon, 296, 456 Muthaura, Francis, 356, 358 Mwangi, Boniface, 201 Mwatela, Jacinta, 355 Mzalendo, 363, 364

#### **N**

 Nadella, Satya, 67 Nairobi availability of qualifi ed human capital, 238–9 availability of support, 237–8 opportunity for on-the-job training, 52 population growth, 16 technology entrepreneurship, 7–8, 228 case study, 265–86 challenges, 251–2, 265–86 recommendations for policy and practice, 283–6 Nairobi Garage . *See* 88mph Naked Pizza, 422, 427 Nandimobile, 72 Naspers, 75, 76 National Agency of Universal Service in Telecommunication/ICT (ANSUT), 63 National Communication Authority (NCA), 64, 65 National Entrepreneurship Development Fund, 443

 National Information Technology Agency (SITA), 64 National Information Technology Development Agency (NITDA), 64 National Optic Fiber Backbone Infra structure (NOFBI), 62, 67 National Peace Accord, 197, 352 NCC . *See* Nigeria Communications Commission (NCC) Ndemo, Bitange and government policy, 67 ( *see also* policy development and implementation) and iHub, 314 and importance of mindset, 465 role in #SomeoneTellCNN, 205–6 as role model, 388 setting up of TEAMS consortium, 16 networks . *See also* technology networks and business relationships, 377, 378, 390 for venture capital deal-sourcing, 437 newness, creation of, 463, 470–3 Ngong Road, Nairobi, 68, 233 NGOs . *See* nongovernment organizations (NGOs) Nigeria economic growth, 60 entrepreneurship in, 405 government credit, 413 ICT examples, 64 mobile market, 62 parallel entrepreneurship in, 415

 supportive government policies, 63–5 technology infrastructure, 62–3 Nigeria Communications Commission (NCC), 64, 65 NikoHapa, 68 NITDA . *See* National Information Technology Development Agency (NITDA) Njoku, Jason, 71 Njoroge, Ken about, 395 conversation with, 396–402 as founder of Cellulant, 68, 113 as role model, 388 Njuguna, Ndung'u, 356 Nkaissery, Joseph, 201, 208 nongovernment organizations (NGOs) early users of email, 28, 29 funding from, 234 grants from, 303 role of, 49–51 nonprofi t markets investors' view on, 279 technology entrepreneurs' use of, 278 nonprofi t organizations . *See also*  iHub; organizational cultural hybirds cultural infl uences, 303–27 diff erence to for-profi t organizations, 305, 309–12 grants from, 304 research on, 210

**O**  Obama, Barak, 66, 206, 207, 263–5, 463

 offi cial development assistance (ODA), 429, 430 offl ine technologies, 31–3 OkHi, 123–31, 422, 471 Okolloh, Ory about, 363 blog post, 193 conversation with, 364–7 and government intervention, 465 as role model, 388 OLX, 76, 118 Omidyar Network, 47, 71, 304, 306, 314, 363–4, 405, 440, 442, 443 1G . *See* fi rst-generation (1G) systems open Source Movement, 135, 137–9, 145 Opera Mini, 190 orange, 57, 61–3, 70, 187, 188, 354 . *See also* Telkom Orange Fab, 70 organizational cultural hybirds . *See also* iHub; 88mph implications of, 322–3 need to take advantage of, 8, 306 recommendations for practitioners, 323–5 in the technology sector, 303–27 theoretical grounding, 306–9 organizational culture . *See also*  worldviews and approaches to technology, 306–9 manifested in worldviews, 371–2n4 nonprofi t and for-profi t, 310–13 research on, 307, 310 theoretical grounding, 306–9 training in for those new to Kenya, 390–1

 Owigar, Judith about, 259 conversation with, 260–4 and importance of mindset, 466 ownership, sharing as an alternative to, 136–7

#### **P**

 Pakistan, 67, 478 Pan-Africanism, in business, 464, 480–1 paper, as technology, 143 parallel entrepreneurship . *See also*  hustling in Africa, 403–17 culture of, 422 implications for business in Africa, 404, 408–9 importance of, 410 recommendations to key stakeholders, 412–13 research into, 408, 409, 414–17 partial credit guarantees (PCGs), 413 PayPal, 102, 108, 111, 296, 456–7, 475 "PayPal Mafi a," 456–7, 475 pension funds, 435, 439, 440 Peremende Movement, 198 Pivot East, 76, 119 policy development and implementation . *See also*  government diffi culties in, 347 disengagement of entrepreneurs, 346 for entrepreneurship, 4, 9, 341, 343, 344, 359, 365, 366

 for entrepreneurship ecosystems, 341, 343, 344, 349 fi ve-point policy, 2 general systems theory, 347–8 for ICT innovation, 274 eff ective, 342 and emerging technology entrepreneurship, 343–4 issues leading to changes, 340, 341 market liberalization, 341–2 M-Pesa, 354–6, 358, 359 Posta, 356–8 public policymaking process, 342–3, 344–6, 348, 349 TEAMS fi bre optic cable, 348–54, 358, 359 importance of local practitioner engagement, 250 importance of political will, 9 interactive decision-making theory, 347–9 and parallel entrepreneurship recommendations, 410–16 supportive, 63–5 political situation Africa, 404 Kenya, 16 population children, 166 growth, 16 youth, 2, 5, 6, 173, 407 Postal Corporation of Kenya (Posta), 19, 355–8, 360 Posta Pay, 355 Pretoria, South Africa, 75 printing, as technology, 133, 143–5, 150

 private equity funding in East Africa, 429, 431 lack of local funding, 440 private sector driving growth of Internet, 30 Internet advocacy, 40 launch of ISPs, 37 mobile phone companies, 61 Privatization Commission, 353 Procurement Act 2005, 351 professional services, 237 lack of, 237 profi tability, importance of, 277, 409, 425 Project Link fi ber, 63 public-private partnerships, 2, 50, 61, 67, 196, 304, 322, 341, 346, 350, 351, 353, 354

#### **R**

 radio, 13, 31, 34, 35, 39, 187, 193, 195, 199 Rancard Solutions, 74 real estate market, disruption, 106 Really Simple Syndication (RSS) feeds, 191 recruitment, 148, 167, 228, 411 regional innovation systems, 229, 231 regulation Internet service providers (ISPs), 64 Kenya, Ivory Coast, Nigeria, Ghana and South Africa ('KINGS'), 64 need for more comprehensive, 174 need for relatively lenient, 246

 of technology industry, 49 of telecommunications, 33–4 relationship management, 373, 377–8 research on challenges to entrepreneurship, 267–70 needed for entrepreneurship ecosystems, 228, 229 need for location specifi c, 475 into organizational culture, 310, 326 into parallel entrepreneurship, 407, 408, 414–17 residence associations, 366 resource-scarce contexts entrepreneurship ecosystems, 227–53 model for emergence of, 232 need for future research, 252–3 recommendations for establishing, 248–52 Retailers, mass, 102 reverse innovation, 482 risk business, 439 dark side of entrepreneurship, 476–8 perception of and tolerance for, 235 Rockefeller Foundation, 3, 87, 170, 274 Rossiello, Elizabeth about, 155 conversation with, 156–61 Rotich, Juliana, 3, 193, 203, 314, 388

 rural areas, access to ICT, 30, 31, 35, 39, 42, 64, 183, 184 Rwanda, 113, 205, 413, 424, 431, 440, 441, 443

#### **S**

 Safaricom and corruption, 340 dominance, 241 and iCow, 185, 186 and iHub, 56, 314 launch of M-Pesa money transfer platform, 17 and mobile money, 17, 59, 61, 187, 355, 356 and mobile phones, 21, 57 and M-Pesa, 17, 21, 56, 59, 64, 454, 455 and venture capital funding, 445 Safaricom Spark Fund, 445 Salim, Ahmed, 196 Sambaza, 21 satellites, 13, 15, 31, 35, 37, 62, 75, 436, 440 Savannah Fund, 46, 48, 304, 385 Schein's three levels of organizational culture framework, 8, 307, 308, 321 school system . *See also* education and Afroes, 91 educational certifi cation, 134 low cost primary education, 147 and mindsets for development, 91–2 teacher training, 148 search funds, 445, 446, 448 second generation (2G) digital cellular communications, 39  security, need for digitization, 222 Seedstars World, 70, 76 Sendy, 115, 118, 120, 233, 296 Shah, Mikul, 117 about, 421 conversation with, 422–7 sharing economy, as an alternative to ownership, 136–7 Shuttleworth, Mark, 55, 75 Silicon Savannah, 7, 17–18, 227–53, 371, 432, 470 Silicon Valley, 18, 22, 53, 68, 71, 73, 75, 76, 124, 130, 190, 230, 232, 261, 262, 273, 310, 314–16, 318, 319, 321, 343, 365, 398, 425, 456, 457 Singapore, 5, 55, 87, 88, 90 single-mindedness, *vs.* hustling, 373–5 SITA . *See* National Information Technology Agency (SITA) slavery, impact of in Africa, 18, 19 SMSGH, 72–4 SNDI . *See* La Société Nationale de Développement Informatique (SNDI) social enterprises DDD Kenya as, 164, 166, 169 and entrepreneurship, 269, 283 for-profi ts perception of, 303, 304, 309, 319 as hybrid organizations, 309 and ICT, 164 and youth unemployment, 468 social entrepreneurship . *See also*  Digital Divide Data (DDD) Kenya concept of, 164–5

 impact sourcing, 165 motivation, 463 technology-based, 6 social media and connectivity, 470 growing infl uence, 190 growth in blogging, 191–3 growth in use of Twitter, 193–4 power of, 208 use for drought fundraising campaign, 196–7 use for medic's protest, 198 use for music promotion, 194, 195 use for peace campaign, 197 use for reporting terrorism, 206, 207 use for school protest, 201–2 use for #SomeoneTell campaigns, 202–3 use in electoral debates, 199 social networking, 188, 190–5, 209, 268, 377, 378, 390, 437, 447 SocialSpot, 69 software developers, 334, 335 #SomeoneTell hashtag campaigns, 202–7 South Africa digital economy, 55–7, 59–66, 74–6, 78 government credit, 413–14 ICT examples, 61 lack of quality middle management, 406 supportive government policies, 63–5 technology infrastructure, 62–3 Spark innovation fund, 422

 start-up ecosystem, Nigeria, 69–71, 73, 317, 447 start-ups challenges to, 411 in East Africa, 439 Ghana, 72–4 and industry events, 76 need for focus, 424, 425 need for more, 53 need for strong and diverse team, 425 Nigeria, 70–2 nurturing, 343–4 South Africa, 74–6 studio business model, 297, 411, 412 technology, 8 US, 439 statistics, need for more on ICT, 175 stock exchanges, 72, 102, 455, 475 stockmarkets, 441, 446, 475 store-and-forward (FidoNet) technology, 28, 31 submarine fi ber optic cables, 16, 39, 352

#### **T**

 Tandaa grant initiative, 240 Tanzania, 113, 148, 156, 173, 332, 397, 413, 431, 433, 440, 441, 447 tariff s, for international calls, 32 Tata, Ratan, 294, 296 TEAMS . *See* Th e East Africa Marine System (TEAMS) fi bre optic cable technology education, 52, 73

 technology entrepreneurship . *See also*  entrepreneurship advice networks, 344 challenges, 8 challenges in Kenya, 7–8, 236, 266, 286 characteristics in Kenya, 453–9 concept of, 19 confl icting worldviews, 372–82 future of for societal development, 11 and fuzzy markets, 277–8 international worldview, 372, 374, 376–80 in Israel, 343 Kenyan worldview, 371–5, 377–82, 385 in 'KINGS' countries, 65–76 mindsets for, 382–6 in Nairobi case study, 265–86 challenges to, 251–2, 265–86 disconnected perspectives as challenges, 265–86 recommendations for policy and practice, 283–6 perceptions of funding availability, 266 perceptions of investment availability, 266 perceptions of skills needed for, 266 prioritising of strategy and planning business skills, 275–6 revolution in, 1–3, 11, 464, 473, 476, 482 role models, 388

 understanding of, 228 worldviews on, 370–3, 382, 386, 391, 392 co-existence of, 391 confl icting, 371–82 management of, 377–8 mindsets, 386–91 technology hubs, 233, 244, 246, 248, 251, 305, 313, 432, 473 . *See also* iHub; innovation hubs technology, in traditional education, 145–50 technology networks establishment of, 31 geographical coverage, 39–40 problems of limited investment, 35 technology parks, plans for, 70, 73 techpreneurs, 160, 374, 376, 377, 384, 391 TED, 178, 295 telecommunications corruption in sector, 339, 340 dominance of global companies, 241 dominance of Safaricom, 61 implementation of new ICT policy, 348 need for market to be developed, 242 need for reliable, 166 regulation, 33–4, 38 vibrancy in 'KINGS' countries, 61–2 Telecommunications Foundation of Africa, 29

 Telecommunications Service Providers of Kenya, 30 teledensity (telephone lines per 100 people) for email, 32 rapid growth in, 28 telephone bureaus, market for, 34, 36 telephone services, 35 Telkom . *See also* orange Kenya, 16, 28, 34, 38, 39, 61, 187, 340, 341, 351, 354 Nigeria, 62 South Africa, 62 Tema, Ghana, 73 terrorism, in Kenya, 174, 191, 199–200, 203, 206–8 Th awte, 55, 75 #Th eAfricaTh eMediaNever ShowsYou, 209 Th e East Africa Marine System (TEAMS) fi ber optic cable, 2, 9, 16–17, 61 3G, in Kenya, 188, 454 3Mice, 398–400, 402 training importance for those new to Kenya, 390–1 as key enabler to ICT ecosystem, 239 lack of for BPOs, 169 lack of for parallel entrepreneurship, 414 on-the-job, 52 in using computers, 16, 52, 266, 438 transaction costs, 99, 121, 134, 136 transaction facilitators, 102, 108–13, 115, 116

 trust lack of as cultural characteristic, 235 lack of for technology products, 278 lack of of venture capital and private equity, 390 Tunapanda Institute, 148 Twitter and electoral debates, 199 growth in use of, 189 importance of in Kenya, 192 and Peremende Movement, 198 #SomeoneTell hashtag campaigns, 202, 204 use for drought fundraising campaign, 196–7 use for music promotion, 193–4 use for peace campaign, 197 use for reporting terrorism, 206–7 use for school protest, 201 Tyco, 351, 374

#### **U**

 Uber, 103–5, 110, 112, 118, 120, 141, 142, 149 Uganda, 148, 156, 202, 203, 332, 397, 424, 431, 433, 440, 441, 447 Umanah, Ibanga about, 292 conversation with, 292–302 Umati Capital, 219–23 unemployment in Africa, 407 perception of, 466 youth, 2, 166, 407, 468

 United Nations (UN), role of, 4, 86, 87, 126 United States (US), technology start-ups, 72 universities, technology education, 3, 6, 28, 45–54, 144, 146, 148, 149, 168, 174, 227, 239, 250, 266, 269, 270, 285, 397 University of Nairobi, 13, 15, 32, 270 Urban Hive, 74 Ushahidi based on non-individual needs, 21 as crowd-sourcing platform, 17, 66 formation, 48 founding of, 193 unique solution, 23 Uwezo Fund, 443

#### **V**

 venture builders, 291, 295–7, 300–1, 445, 446, 448, 472 . *See also*  Brave Venture Labs venture capital . *See also* funding; investment combined with the chama, 390 in East Africa, 429–48 discussion, 438–43 literature review, 431–2 recommendations for, 443–7 research methods, 432–4 research results, 434–8 right model for, 10, 430 lack of, 239–40 South Africa, 74–6

 Venture Capital Trust Fund, 73 Verisign, 55, 75 very-small-aperture terminals (VSATs), 35, 37 violence, political in Africa, 406 Virtual City, 52, 69 Vision 2030 . *See* Kenya Vision 2030 Vodacom, 55, 56, 62–4, 75, 87, 159 Vodafone, 17, 62, 63, 245 Voice telephony, dominant product, 36 voids . *See* markets, voids vouchers, digital gift, 424, 426 VSATs . *See* very-small-aperture terminals (VSATs)

#### **W**

 Waigi, Munyutu about, 219–20 conversation with, 220–3 Wananchi Group (now Zuku), 14, 67, 314 . *See also* Zuku Wanjiku, Becky, 47, 188, 314 Waweru, John, 350, 352 Were, Daudi, 191 Westgate Mall attack, and Twitter, 199, 458 Weza Tele, 68, 115, 117–18, 233 WhatsApp, 160, 209 Where Is My Transport, 120 Whole Foods, 102 Windows 10 (Microsoft), 67 Windows 95 (Microsoft), 16 Winning in Emerging Markets (Khanna and Palepu), 101 women in technology, 76, 143, 236–9

 World Bank *Doing Business* report (2015), 60, 99 employment fi gures, 2 InfoDev, 274, 323 worldviews . *See also* culture; mindsets co-existence of, 391 confl icting, 371–82 international, 369–92 Kenyan, 10, 371–5, 377–82, 385, 391 management of, 377–8 and technology entrepreneurship, 370–3, 382, 386, 391, 392 and technology infrastructure, 371n3

**Y**

 Yaba, Lagos, 71 Yahoo Messenger, 190  Yale University, human capital contracts, 412 Yelp, 107, 111 Yorobi, Bacely, 69 Youth population, 2, 173, 407 Youth unemployment, 2, 166, 407, 468 YouTube, 123, 146, 195, 199 YuMobile, 187

#### **Z**

 Zambia, 68, 113, 158, 332, 397, 406 Zimbabwe, 57, 397 Zimbabweans on Twitter (Twimbos), 204, 205 ZTE, 190 Zuckerberg, Mark, 56, 147, 374 Zuku (formerly Wananchi Group), 14, 67, 314


**3. Results and Discussion**

Unpretreated agricultural residues are resistant to cellulolytic enzymes and characterized by a low reducing sugar yield in hydrolysis with a mixture of *P. verruculosum* B151 cellulase complex and F10 β-glucosidase. The wheat straw convertibility was 12%. For the sugar beet pulp, it was 20%, for oat husks it was 5%, for sunflower peels it was 3%, for corn stalks it was 10%, and for bagasse it was 17%. Only the soy husk convertibility was relatively high, at 31% (Table 2).

**Table 2.** Convertibility of different cellulose-containing materials in hydrolysis by a mixture of *P. verruculosum* B151 cellulase complex and F10 β-glucosidase.

**Table 2.** *Cont*.

Mechanical pretreatments such as fine ball milling or extruding have resulted in increasing the convertibility of these substrates 1.35–3.75 fold. The data of enzymatic hydrolysis obtained for mechanically pretreated materials have shown that the ball milling (which gives an average particle size of less than 20 µm) of wheat straw and bagasse results in increased convertibility to 45% and 42%, respectively. The ball milling of sunflower peels leads to a very limited improvement in convertibility at 7%, which indicates that they are practically not digestible by cellulolytic enzymes. Sugar beet pulp pretreatment by extrusion has also shown a limited improvement in convertibility (to 27% only).

The wheat straw convertibility after delignification with hot alkaline solution increased 4.6-fold (up to 55%).

Steam explosion pretreatment with different additives (H2SO4, Ca(OH)2) demonstrated that wheat straw, out husks, soy bean husks, corn stalks, and bagasse were easy to hydrolyze with enzymes, and this pretreatment enhanced the convertibility up to 69–75%, 76%, 58%, 36–55%, and 34–41%, respectively. Supplementation with H2SO4 and Ca(OH)2 has shown an opposite result for different materials: calcium hydroxide is preferable for bagasse pretreatment (7% higher sugar yield), while a corn stalk pretreatment required sulfuric acid (19% higher sugar yield). Wheat straw steam pretreatment required no additives.

The enzymatic hydrolysis of unpretreated food-industry waste has shown that this kind of cellulose-containing material is far from being a potential source of simple sugars for biotechnology. Thus, the convertibility of brewing waste, destarched corn, and wheat bran was very low, at 10%, 12%, and 14%, respectively. The convertibility of wet and dry distillers grains hydrolysis was slightly higher, at 18% wet and 16% dry, respectively.

Pulp and paper production is a large-tonnage and streamlined industry. The range of products in this area is very wide. They differ in the raw materials (hardwood or softwood, others) used and the way they are produced (wood cooking, bleaching). Creating an integrated biorefinery plant around existing pulp and paper mills would enhance their marketability by efficient converting all biomass components into value-added products [32]. The Kraft pulping process is a promising pretreatment technology for biocatalytic conversion of cellulose and hemicelluloses to glucose and other monosaccharides [33,34]. The convertibility of newer dry as well as dried kraft fibers representing by bleached and unbleached soft wood and hardwood pulp was evaluated (Table 1). The highest convertibility was demonstrated by wet bleached softwood pulp, at 78%; the reason for the high convertibility is the almost complete removal of lignin by the Kraft process (a remaining lignin content was 2–3% [33]). The convertibility of wet bleached hardwood pulp was 58%; this is lower compared with bleached softwood pulp because of the xylan influence [33]. Unbleached wet softwood and hardwood pulp had approximately a 1.1 times lower convertibility compared with similar types of bleached pulp; the decrease in convertibility of unbleached pulp is explained by the higher lignin content.

The drying and subsequent hornification of all kraft pulps types had a significant effect on convertibility as it reduces swelling and the cellulose fiber accessibility [35] and causes a collapse in the pore structure [36]. The convertibility was reduced by 1.3–1.4 times compared to wet pulp.

The recycling and utilization of wood industry wastes and forestry residues is crucial for wood processing and environmental security. In total, five types of wood species were included in this study. The convertibility of pine, larch, aspen, and hevea sawdust was low and found to be in the range of 4–8% (Table 1). Mechanical pretreatment (dry fine ball-milling that results in an average particle size less than 20 µm) has resulted in a significant increase in the convertibility of pine wood and aspen wood to up to 45–50%; in the case of larch, it is up to 22%. The increase in convertibility was due to defibrillation and reduction in the crystallinity of fibers and increasing surface area related to reducing particle size [35]. Despite its high efficiency, fine ball-milling has serious disadvantages, such as being energy consuming and difficulties in scaling up [37]. In view of the rising energy prices and power intensity, fine milling is not economically reasonable [38].

To counteract these disadvantages, less intensive milling processes can be combined with chemical and physicochemical pretreatments such as dilute acid and organosolv pretreatments. We have studied the convertibility of aspen wood subjected to pretreatment by different water and organic solutions of mineral acids. Relatively low temperatures of pretreatment process were selected to prevent the unfavorable degradation of carbohydrates and inhibitors formation.

Pretreatment of aspen wood by dilute acids: Five samples were obtained using dilute sulfuric acid pretreatment of aspen wood particles (200–300 µm). The results demonstrate a linear correlation between acid concentration and substrate convertibility (Table 3). There was no difference found (58.4% convertibility) for samples processed with 12.7% and 8.7% sulfuric acid, which could mean that the maximum available polysaccharides for enzymatic hydrolysis due to the solubilization of hemicelluloses are limited. Further reduction in the acid concentration to 4.4% and 1.8% results in the convertibility decreasing to 44.2% and 42.9%, respectively. Further reduction in the acid concentration to 0.9% provides a convertibility of 41.6%, which is just 1.4 times lower than the result obtained by 12.7% acid. Such a reduction in chemical consumption can be economically feasible even with a lower biomass convertibility.

**Table 3.** Convertibility of aspen wood pretreated using different types of acid-containing solutions at elevated temperatures.

Enhancing the hydrolysis of lignocellulose biomass for the efficient conversion of cellulose and hemicellulose by pretreatment using nitric acid has not been highly studied compared to sulfuric acid. To estimate the influence of nitric acid on the convertibility of 200–300 µm aspen wood in severe and mild conditions, another series of experiments was carried out.

The experimental results demonstrate that the reducing sugars yields after a relatively mild pretreatment at 100–130 ◦C, 5–6 at, and 1–4.8% nitric acid were purely comparable, at about 60% (Table 3). Maximum convertibility was achieved with a subsequent elevation of gas pressure. The aspen wood convertibility enhanced significantly from 60.6% to 78.7% as the pressure increased from 9 to 18–22, while the temperature and acid concentration remained constant (125 ◦C, 4.8%). These nitric acid

concentration and pressure values found in this study are optimal for pretreatment, since increasing the temperature up to 160 ◦C results in a convertibility below 50% for acid concentrations of 0.3–0.7%. There was no additional effect on the reducing sugars yield when the pressure was raised from 18 to 22 at.

It could be concluded that aspen wood pretreatment with dilute nitric acid (convertibility 78.7% at an acid concentration of 4.8%) is more efficient than with dilute sulfuric acid (convertibility 58.7% at an acid concentration of 12.7%) but requires more complex equipment.

Organosolve pretreatment of aspen wood: The results obtained in this study demonstrate that dilute acid pretreatment is very effective. However, after such pretreatment lignin solubilized poorly [39], even though the hemicellulose matrix is being dissolved. Thus, the next panel of experiments was aimed to discover best conditions for fractionation and recovery of lignin, cellulose, and hemicelluloses. All the experiments were conducted at constant temperature 140 ◦C for the same time 1 h, but at different concentrations of organic solvents (ethanol and *n*-buthanol) and sulfuric acid (0.18–0.54%) as a catalyst.

The data display that 50% (*v*/*v*) alcohol–water mixtures have the same efficiency of 36–37% with 0.36% acid. Using a 0.54% acid concentration, 65% *n*-butanol is more preferable than 65% ethanol, ensuring a convertibility of 58.7% and 48.3%, respectively (Table 3). Organosolve pretreatment with 80% alcohol results in a lower convertibility (43.9% and 54.1% for ethanol and *n*-butanol respectively), but *n*-butanol still provided a better enzymatic digestibility. This likely could be explained as the swelling of cellulose fibers decreased as the ethanol concentration increased [40].

During organosolve pretreatment with *n*-butanol, three fractions were obtained: black liquor containing dissolved lignin, hemicellulose-enriched liquid fraction, and cellulose-containing solid fraction [41]. This spatial separation also could explain better biomass hydrolysability after *n*-butanol pretreatment. Previously [42], it has been found that the swelling of cellulose in organic solvent strongly depends on the species of organic solvents—the solvent basicity, the molar volume, and the hydrogen bonding capability—thus, *n*-butanol is more significant in two-component mixtures. This was shown in experiments with alcohol concentrations of 25% EtOH + 25% BtOH (convertibility 54%) and 40% EtOH + 10% BtOH (convertibility 51%). However, in general, more concentrated *n*-butanol single-component mixtures are preferable to two-component mixtures.

Decreasing acid concentrations from 0.36% to 0.18% resulted in a lower convertibility using the same mixture composition (20% EtOH + 40% BtOH)—52% and 46%, respectively. At an acid concentration of 0.18%, this mixture composition has no effect on the convertibility.

These results indicate that alcohol-water mixtures allow using less concentrated acids, while biomass components could be fractionated and alcohols could be recirculated. In this study, the optimal conditions for pretreatment were found: 140 ◦C, 1 h, 0.54% sulfuric acid, 65% *n*-butanol. These conditions lead to a 7.4-fold increase in the convertibility or aspen wood (59% compared to 8% of untreated substrate).


**3. Description of the bridge**

The bridge is located at the Primary State Highway No.1, Seattle Freeway Ravenna Boulevard Overcrossing North Bound. Figure 1 shows an aerial view of the bridge. The North Bound Bridge is the first bridge from below shown in the picture. The bridge length is 1310 ft back to back of pavement seats and consists of twenty spans. Plan and elevation views are shown in Figure 2 and Figure 3.

**Figure 1.** Aerial view of the North Bound bridge

Nonlinear static analysis under monotonically increasing lateral loading is becoming an increasingly popular tool for seismic performance evaluation of existing and new structures. Pushover analysis can be viewed as a method for predicting seismic force and deformation demands, which accounts in an approximate manner for the redistribution of internal forces occurring within the inelastic range of structural behavior. It is expected to provide information on many response characteristics that cannot be obtained from an elastic static or dynamic analysis. Pushover analysis is based on the assumption that the response of the structure can be related to the response of an equivalent SDOF system. This implies that the response is controlled by a single mode, and that the shape of this mode remains constant through the time history response. These assumptions are likely to be reasonable if the structure response is not severely affected by higher mode effects, or the structure has only a single plastic mechanism that can be detected by an invariant load pattern. The use of at least two load patterns that are expected to bound inertia force distribution is recommended. For structures that vibrate primarily in the fundamental mode, pushover analysis will very likely provide good estimates of global as well as local inelastic deformation demands. It will also expose design weaknesses that may remain hidden in an elastic analysis. Such weaknesses include storey mechanisms, excessive deformation demands, strength irregularity, and overloads on potentially brittle elements, such as columns and connections. On the negative side, the most critical is the concern that the pushover analysis may detect only the first local mechanism that will form in an earthquake and may not expose other weaknesses that will be generated when the structure's dynamic characteristics change after the formation of the first local mechanism.

238 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

The purpose of this research is to evaluate the displacement capacity of bents from a long span bridge. A three-dimensional nonlinear finite-element model of the bridge bents were devel‐ oped to determine the inelastic response by performing nonlinear pushover analysis. Modal pushover analyses were carried out in the transverse direction. Detailed data of performance was collected and interpreted to use as a baseline in a parametric study. Separate parametric study was carried out on a single column within this bridge in order to locate appropriate plastic hinge locations. These results were then transferred to individual bents, where multiple columns were modeled based on the results from the single column parametric study.

The bridge is located at the Primary State Highway No.1, Seattle Freeway Ravenna Boulevard Overcrossing North Bound. Figure 1 shows an aerial view of the bridge. The North Bound Bridge is the first bridge from below shown in the picture. The bridge length is 1310 ft back to back of pavement seats and consists of twenty spans. Plan and elevation views are shown in

**2. Objectives of the analysis**

**3. Description of the bridge**

Figure 2 and Figure 3.

**Figure 2.** Plan view of the North Bound Bridge

**Figure 3.** Elevation view of the North Bound Bridge

The superstructure is composed of pre-tensioned concrete beams. Each span includes twelve girders, and the general girder cross-section varies for each span. This complicates the calculation of the total mass of the superstructure. In order to simplify the procedure, indi‐ vidual span cross-sections were drawn in AutoCAD. The sections can be found is Figure 4 relating them to the spans they are assembled for. A table with calculated weight and length for each span can be found in the Appendix. Overlaid on top of the girders is a 5 in thick, approximately 60 ft wide reinforced concrete deck slab.

**Figure 5.** Cross-Beam Plan for Bents

**Figure 6.** Section Thru Cross-Beam

The columns are spaced at 18 ft centerline to centerline. Each column is hollow with an outer diameter of 48 in and a wall thickness of 5 in. Twelve evenly spaced No. 5 bars provide the longitudinal reinforcement within each column. The columns also include twelve No. 3 steel

Pushover Analysis of Long Span Bridge Bents

http://dx.doi.org/10.5772/52728

241

**Figure 4.**  Five are 6-column bents (#1-6), three are 7-column bents (#18-20) and ten are 4-column bents (#7-17). The cross-beam plans for the three types of bents are shown in Figure 5. Each bent has a unique elevation above the ground. Also, because of the curved shape of the bridge, each bent has a slight rotation in the vertical direction. Consequently, there is column height variation within each bent. The various column height values can be found in the Appendix.

At each bent, a 3x4.6 ft crossbeam transversely connects the columns. Figure 6 below shows the geometry and steel reinforcement. The length of the beams varies for each bent, which can be found in the Appendix. The steel reinforcement consists of nine No. 10 bars located at the top and at the bottom of each crossbeam. Two No. 5 bars are located at the side edges and run longitudinally along the crossbeam. For shear reinforcement, No. 5 stirrups are spaced evenly along each member.

**Figure 5.** Cross-Beam Plan for Bents

The superstructure is composed of pre-tensioned concrete beams. Each span includes twelve girders, and the general girder cross-section varies for each span. This complicates the calculation of the total mass of the superstructure. In order to simplify the procedure, indi‐ vidual span cross-sections were drawn in AutoCAD. The sections can be found is Figure 4 relating them to the spans they are assembled for. A table with calculated weight and length for each span can be found in the Appendix. Overlaid on top of the girders is a 5 in thick,

There are a total of 19 bents in the bridge. Five are 6-column bents (#1-6), three are 7-column bents (#18-20) and ten are 4-column bents (#7-17). The cross-beam plans for the three types of bents are shown in Figure 5. Each bent has a unique elevation above the ground. Also, because of the curved shape of the bridge, each bent has a slight rotation in the vertical direction. Consequently, there is column height variation within each bent. The various column height

At each bent, a 3x4.6 ft crossbeam transversely connects the columns. Figure 6 below shows the geometry and steel reinforcement. The length of the beams varies for each bent, which can be found in the Appendix. The steel reinforcement consists of nine No. 10 bars located at the top and at the bottom of each crossbeam. Two No. 5 bars are located at the side edges and run longitudinally along the crossbeam. For shear reinforcement, No. 5 stirrups are spaced evenly

approximately 60 ft wide reinforced concrete deck slab.

240 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

**Figure 4.** Superstructure Sections

along each member.

values can be found in the Appendix.

**Figure 6.** Section Thru Cross-Beam

The columns are spaced at 18 ft centerline to centerline. Each column is hollow with an outer diameter of 48 in and a wall thickness of 5 in. Twelve evenly spaced No. 5 bars provide the longitudinal reinforcement within each column. The columns also include twelve No. 3 steel cables each post-tensioned initially to 61 kips. Transverse reinforcement is provided by No. 2 spiral hooping spaced at 6 in on center. Figure 7 shows the plan column section. The columns are extended approximately 27 ft into the ground to act as piles.

**Figure 7.** Plan Column Section

The columns and crossbeam were cast monolithically adding considerable rigidity to each bent. Figure 8 shows the elevation view of a typical bent. Further, the top 4 ft of each column is filled with class A concrete. This fill is further reinforced with sixteen No. 8 bars longitudi‐ nally, and No. 3 hoops spaced at 12 in transversely. In this section of the column, the hollow column is transversely reinforced with No. 2 spiral hooping spaced at 3 in over center. Figure 9 shows a typical pile.

**Figure 9.** Typical Pile

**4. Modeling of the bents**

represented in 3D in Figure 10.

A spine model of each bent is created in the finite element program SAP2000. Line elements can behave three-dimensionally in the form of beam, beam-column elements and springs. The superstructure is represented as a distributed dead load which represents the dead weight of the superstructure based on tributary length of related spans for each bent. A table in the Appendix provides the distributed load values used in the analysis for each bent. The soilstructure interaction is represented by springs. In order to capture nonlinear behavior of the columns, plastic hinges were defined at maximum moment points. The general model is

Pushover Analysis of Long Span Bridge Bents

http://dx.doi.org/10.5772/52728

**Figure 8.** Elevation View of Bents

**Figure 9.** Typical Pile

cables each post-tensioned initially to 61 kips. Transverse reinforcement is provided by No. 2 spiral hooping spaced at 6 in on center. Figure 7 shows the plan column section. The columns

The columns and crossbeam were cast monolithically adding considerable rigidity to each bent. Figure 8 shows the elevation view of a typical bent. Further, the top 4 ft of each column is filled with class A concrete. This fill is further reinforced with sixteen No. 8 bars longitudi‐ nally, and No. 3 hoops spaced at 12 in transversely. In this section of the column, the hollow column is transversely reinforced with No. 2 spiral hooping spaced at 3 in over center. Figure

are extended approximately 27 ft into the ground to act as piles.

242 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

**Figure 7.** Plan Column Section

9 shows a typical pile.

**Figure 8.** Elevation View of Bents

#### **4. Modeling of the bents**

A spine model of each bent is created in the finite element program SAP2000. Line elements can behave three-dimensionally in the form of beam, beam-column elements and springs. The superstructure is represented as a distributed dead load which represents the dead weight of the superstructure based on tributary length of related spans for each bent. A table in the Appendix provides the distributed load values used in the analysis for each bent. The soilstructure interaction is represented by springs. In order to capture nonlinear behavior of the columns, plastic hinges were defined at maximum moment points. The general model is represented in 3D in Figure 10.

The cross-sections of the cap beam and the column were accurately modeled by using the subprogram offered in SAP2000 called Section Designer. Section Designer lets the user draw the shape of the cross-section and also include the steel reinforcement. Figure 11 shows the

The columns were considered fixed in the cap beam. Nonlinear springs along the pile shafts were used to model the resistance provided by the surrounding soil. The L-Pile software (2002) was used to compute the P-Y curves, based on the stiff sand soil model with free water at 15

To build an exact computer model of a structure beard against underground elements-piles it is necessary to know how interaction between soil and a pile can be simulated, to get more precise result of the analysis. The p-y curves is a strait interpretation of the relation between deflection of an element and soil pressure on a particular depth. The pressure from the soil on the element is distributed within certain length which depends on the number of springs

A physical definition of the soil resistance *p* is given in Figure 13. There was made an assump‐ tion that the pile has been installed without bending so the initial soil stresses at the depth *xi* are uniformly distributed as shown in Figure 13*b*. If the pile is loaded laterally so that a pile

the soil stresses will become unbalanced as shown in Figure

with units F/L equation 1.

Pushover Analysis of Long Span Bridge Bents

http://dx.doi.org/10.5772/52728

245

drawn sections used in the analysis.

**Piles**

depths.

assigned to it Figure 12.

**Figure 12.** Model of laterally loaded pile

occurs at the depth *xi*

13*c*. Integration of the soil stresses yielding the soil resistance *pi*

deflection *yi*

**Figure 10.** Model of Six-Column Bents

**Figure 11.** Bent Element Cross-Sections

The cross-sections of the cap beam and the column were accurately modeled by using the subprogram offered in SAP2000 called Section Designer. Section Designer lets the user draw the shape of the cross-section and also include the steel reinforcement. Figure 11 shows the drawn sections used in the analysis.


Nonlinear Systems -Theoretical Aspects and Recent Applications

*Edited by Walter Legnani and Terry E. Moschandreou*

Published in London, United Kingdom

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Nonlinear Systems -Theoretical Aspects and Recent Applications http://dx.doi.org/10.5772/intechopen.77467 Edited by Walter Legnani and Terry E. Moschandreou

Part of IntechOpen Book Series: Nonlinear Systems, Volume 2 Book Series Editor: Mahmut Reyhanoglu

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*2.1. Study Area*

The study was conducted in a marshland area including Sanlian village (30.642447, 117.346828 and Guifan village (30.574982, 117.410960), in Guichi district, Anhui Province, which is located in the middle and lower reaches of the Yangtze River Basin, the largest river in China (Figure 1).

**Figure 1.** Location of the study area in Guichi district, Anhui Province, China.

Its humid subtropical monsoon climate has annual average temperatures of 16 degrees Celsius and annual average rainfall of 1600 mm. This provides a suitable environment for the survival of Schistosoma japonicum. There are many small hills full of swamps, ponds and ditches in Guichi. This

feature makes Guichi a typical schistosomiasis epidemic area. In addition, people in Guichi live along rivers or lakes, and their lifestyles area mainly involve farming and grazing, fishing and lake grassing. These labor activities expose local residents to be infected by schistosomiasis [7]. At the end of 2012, the total habitat area of snails in Guichi district was approximately 26.2715 km2 [8]. Of 650,000 people in Guichi, about 400,000 people were at risk of schistosomiasis, and the endemic area covered 16 towns and 165 villages [8]. All subjects gave their informed consent for inclusion before they participated in the study. The research was approved by the Medical Ethics Committee of Fudan University School of Public Health (IRB#2011-03-0270).


**3. Results**

Out of 40 patients, 32 (80%) patients were below 30 years of age while only 8 (20%) patients were above the age of 30 years. The gender distribution showed that 88 (58.7%) of the patients were male and 62 (41.3%) were female. Most of the patients, 26 (65.0%), were nonsmokers. The size of the preoperative periapical lesion was arbitrarily categorized into 6 mm or less and more than 6 mm for this study. The results showed that half of the patients had a periapical lesion size of 6 mm or less, while another half had more than 6 mm. Preoperative pain was present in 22 patients (55.01%) (Table 1).

**Table 1.** Descriptive Statistics for Demographics.

There was a statistically significant association between periapical healing and age (*p*-value = 0.025), smoking (*p*-value = 0.029) and the size of periapical lesion (*p*-value < 0.001). After periapical surgery, healing was observed in 29 patients, in which 26 (81.3%) patients were below the age of 30 years while only 3 (37.5%) patients were above 30 years of age on one year follow-up. Similarly, 22 nonsmoking patients (84.6%) revealed periapical healing compared to 7 (50%) smoking patients. Although the success of healing was higher in males, at 78.6% (22/28), compared to females, at 58.3% (7/12), no statistically significant relationship was found between gender and healing (*p*-value = 0.254). Likewise, no significant association between the presence of preoperative pain and postoperative healing (*p*-value = 0.723) was observed (Table 2).

**Table 2.** Relationship of Periapical Healing with Age, Gender, Smoking, Preoperative pain, and Periapical lesion size on one year follow-up.

¥ Chi-squared test, ˆ Fisher's Exact Test.

#### **4. Discussion**

The current study was conducted to evaluate the effect of various preoperative factors such as age, gender, smoking, preoperative pain, and preoperative periapical lesion size on the outcome of surgical endodontic treatment. The results of the study showed a statistically significant relationship between periapical wound healing and age, smoking, and preoperative lesion size.

Surgical endodontic retreatment is employed in managing recurrent secondary periapical lesions as a consequence of primary root canal treatment failure [19]. Surgical endodontic retreatment involves re-root canal treatment with subsequent sectioning of the apical end of the root followed by retrograde obturation and establishment of the apical seal of the root canal system. This apical seal facilitates healing of the periapical tissues by preventing the ingress of microbial irritants into the periapical area and concomitant tissue reaction [3].

It has now become clinically evident that even if the surgical endodontic treatment has been conducted using the same procedure, patients respond differently with respect to periapical wound healing [3,4]. This difference in periapical wound healing may be due to the presence of various preoperative factors such as pain, swelling, sinus tract, smoking, and size of the periapical lesion. However, evidence to support the influence of these preoperative factors on the outcome of periapical surgery are conflicting. In addition, most of the clinical studies that exist in the literature are retrospective [8,20,21]. The novelty

of this study lies in following patients prospectively and opening an avenue for further research in this direction.

Age is considered a prognostic indicator of outcome for many surgical procedures [4]. In this study, 81.3% healing was achieved in patients below 30 years of age. This finding is in agreement with Kriesler et al. [22] They found a 95% success in patients between 21 to 40 years of age. Contrarily, Barone et al. [23] reported 84% success in periapical healing in patients above 45 years of age, compared to 68% in patients below 45 years of age. This study observed no significant relationship between healing and gender. Similarly, a large number of studies did not find gender as a prognostic factor for periapical surgery [18,24,25]. However, Peñarrocha-Diago et al. reported a higher success in males (60%) compared to females (40%) at 6 months [26].

The habit of smoking can influence the outcome of periapical surgery by several plausible biological mechanisms. First, smoking interferes with the function of lymphocytes, leukocytes, macrophages and increases the level of various proinflammatory mediators, such as TNF- α, IL-6, and C-reactive protein [27,28]. Second, smoking decreases the fibroblast migration to the periapical wound area and stimulates the function of osteoclastic cells, which encourage bone resorption [29]. Third, smoking causes morphological alteration in the microvasculature, which in turn disturbs the oxygen and nutrient supply to the periapical wound area [30]. In the current study, a positive trend of healing was observed in nonsmokers (84.6%). This finding conforms to Lopez et al. [8] and Kirkevang et al. [31], who found a statistically significant association between smoking and periapical healing. On the other hand, Rodriguez et al. [32] and Balto et al. [33] reported no significant difference in periapical periodontitis between smokers and nonsmokers.

The presence of preoperative pain and swelling or sinus tract may also govern the outcome of periapical surgery as indicated by many studies. Von Arc et al. [20] revealed that the presence of preoperative signs and symptoms discourages healing. They postulated that the healing potential of surgical wounds could be significantly affected by the stage of infection at the time of surgery, which is influenced by preoperative pain and signs. Similarly, Kreisler et al. [22] also claimed a lower success rate in patients with pretreatment pain. Contrastingly, the present study did not find any difference in the healing success rate in relation to the presence of preoperative pain, similarly to Song et al. [34] and Peñarrocha et al. [35]. The reason for there being no relation between the presence of preoperative pain and periapical healing after surgical endodontic treatment may be due to the fact that same treatment protocol was used for every patient and all treatment procedures were performed by the principal investigator.

Another important prognostic factor in periapical healing is the size of the lesion. In the present study, 100% successful healing was observed in patients with preoperative lesions of less than 6 mm, while 45% healing success was evident in patients with more than 6 mm of preoperative lesion size. A large number of studies have described the favorable prognosis after periapical surgery in patients with preoperative lesions of less than 5 mm in diameter [20,26,34]. Alternatively, Barone et al. [23] found an 80% success rate in periapical lesions of less than 10 mm in size at the time of surgery, compared to 53% success in periapical lesions of more than 10 mm in size.

Multiple systemic diseases are known to interfere with periapical healing, such as diabetes, hypertension, osteoporosis, or any uncontrolled systemic disease. Hyperglycemia increases the level of inflammatory markers and influences the various functions of the patient immune system [36]. Similarly, hypertension is associated with alterations in response and differentiation of bone cells at various levels [21]. Moreover, the drug bisphosphonate is commonly used for the treatment and prevention of osteoporosis and it is well-established that it reduces bone remodeling [37], therefore patients with these systemic diseases were excluded from this study, in addition to the patients with a preexisting medical condition such as pregnancy and lactating mothers. Further prospective studies are required to evaluate postoperative healing in relation to the presence of different chronic systemic diseases using microsurgical techniques.

The findings of the study must be seen in light of some limitations. First, periapical surgery was performed by the conventional approach rather than microsurgical. The microsurgical approach offers numerous benefits such as small osteotomy, easy identification of root apices, visualization of minor anatomical variations, and preservation of cortical bone and root length by nearly 90-degree root resection. Several studies have shown the superiority of microsurgical endodontic treatment in comparison to traditional root-end surgery [38,39]. Second, the healing was assessed on a digital periapical radiograph, using a cone indicator and reference marker to ensure constant distance and angle between X-ray cone and sensor on every shoot. Moreover, exposure time, tube current, and voltage were the same on recall images. However, the X-ray image obtained was still two-dimensional, with a high probability of missing details in the third dimension. Nowadays, cone beam computed tomography (CBCT) is considered a standard of care [40] and has great value in establishing the correct diagnosis and in evaluating periapical healing after surgical endodontic treatment. Third, periapical surgery was performed on single-rooted anterior teeth only, multirooted posterior teeth where surgical access to treatment is difficult and high chances of variation in root morphology were excluded. Lastly, the sample size of the study was small due to the constrained study time, therefore; the results should be interpreted cautiously and may not represent the large population.

There is also a dire need to design a questionnaire which can evaluate the healthrelated quality of patients' life after endodontic surgery, similar to The University of Washington Quality of Life Questionnaire (UW-QOL) for head-and-neck cancer patients [41]. Future studies are also desirable with the inclusion of a large sample size, multirooted teeth and various other treatment-related factors such as microsurgical technique, type of root-end filling, method of root-end resection and retrograde cavity preparation. Addition of tools such as fractal analysis used for the quantitative evaluation of bone trabeculation following periapical surgery will also help in the early detection of complex structural patterns in the trabecular bone [42].

#### **5. Conclusions**

Patient age, smoking status, and size of the preoperative lesion had a strong influence on periapical healing after surgical endodontic treatment. However, other perioperative (treatment-related) factors should also be taken into account to establish conclusive evidence.

**Author Contributions:** Conceptualization, M.A.A., N.M. and S.H.A.; methodology, M.A.A.; software, M.A.A.; validation, F.V., M.M., A.A. and M.F.B.; formal analysis, M.A.A.; investigation, M.A.A. and A.A.; resources, N.M. and S.H.A.; data curation, M.F.B.; writing—original draft preparation, M.A.A. and A.A.; writing—review and editing, M.A.A., F.V., M.M., A.A. and S.H.A.; visualization, N.M.; supervision, N.M., S.H.A. and M.F.B.; project administration, M.A.A. and A.A.; funding acquisition, M.A.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors are grateful to the Deanship of Scientific Research, King Saud University for supporting through Vice Deanship of Scientific Research Chairs, Engr. Abdullah Bugshan research chair for Dental and Oral Rehabilitation.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Institutional Review Board, Dow University of Health Sciences (IRB-862/DUHS/Approval/2017/50) on 10 July 2017.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to ethical concerns.

**Conflicts of Interest:** The authors declare no conflict of interest.