**3. Liquid chromatography in the analysis of flavonoid metabolism**

To show the chemical variety of flavonoids, chromatographic methods have been utilized to examine their structures. Previously, the major methods used to analyze flavonoids were paper chromatography, thin layer chromatography, column chromatography, and liquid chromatography (LC) [36]. Efficient screening of plant extracts may be accomplished using biological assays as well as chromatographic techniques such as high-performance liquid chromatography (HPLC) in conjunction with different detection modalities [37]. Because it permits systematic profiling of complex plant samples and especially focuses on their identification and consistent assessment of the found compounds, HPLC is a potent tool for the quick investigation of bioactive ingredients. Modern HPLC separation of flavonoids nearly entirely uses reversedphase liquid chromatography (RP-LC), with significant exceptions being normal phase liquid chromatography (NP-LC) for oligomeric proanthocyanins [38] and the recent rising use of hydrophilic interaction chromatography (HILIC). Other flavonoid separation methods include mixed-mode ion-exchange-reversed phase separation of anthocyanins [39–41], size exclusions chromatography (SEC) analysis of flavonol glycosides [42], and theaflavins and proanthocyanidins [43]. However, because of the infrequent usage of the later modes, this chapter will concentrate mostly on RP-LC in line with the extent and predominance of this method in flavonoid literature.

RP-LC has proved its applicability for the separation of flavonoids depending on the nature of the aglycone (including the oxidation state, substitution patterns, and stereochemistry), the type and degree of glycosylation, and the nature and degree of acylation. The vast majority of RP-LC separations are accomplished using C18

#### *Application of Liquid Chromatography in the Analysis of Flavonoid Metabolism in Plant DOI: http://dx.doi.org/10.5772/intechopen.107182*

octadecyl-silica (ODS) phases, however, C8 [44], C12 [45], phenyl or phenyl-hexyl [46–50], pentafluorophenyl (PFP) [51–53] and polar embedded RP phases [54–56] as well as polymeric RP-LC phases were still widely used [57]. Aqueous/organic phases including methanol, acetonitrile, and less commonly tetrahydrofuran [58], isopropanol [59] or ethanol [57], and acidic modifiers such as acetic acid, formic acid, ammonium acetate, or trifluoroacetic acid (TFA) [59] are typical mobile phases (phosphoric, citric, or perchloric acids have also been used in combination with UV detection, although these are not suited to hyphenation with MS). Highly acidic mobile phases (>4–10% formic acid, 0.1–0.6% TFA) [60–63] are utilized for anthocyanins to assure the presence of flavylium cationic species in solution and therefore increase chromatographic efficiency. To detect and/or identify flavonoids, a variety of detectors may and have been used in conjunction with HPLC separation. These include electrochemical detection (ED) [64, 65], fluorescence (FL) [66], UV–Vis, diode array [59, 67], NMR [68, 69], and of course MS detectors [70, 71]. The most prevalent currently are diode array and MS detectors, which will be explored briefly in this and the next sections.

#### **3.1 Liquid chromatography (LC) with ultraviolet (UV) detector**

Particularly in early flavonoid research, the conjugated aromatic nature of flavonoids proved to be a significant advantage: absorption at relatively long wavelengths increases the selectivity of qualitative and quantitative spectrophotometric methods, and the distinctive spectra of various classes of flavonoids allow differentiation between them. These qualities are similarly helpful when HPLC separation is combined with UV–Vis detection. Flavonoids exhibit two UV–Vis absorption maxima: Band II (Band II), which is attributed to the A-ring, and Band III (Band III), which is attributed to the B-ring (Band 274 I). Due to the fact that it offers more specialized information and since all flavonoids absorb between 240 and 285 nm, the latter of these is more useful. Due to the absence of conjugation between the A and B rings, flavanols, flavanones, dihydroflavonols, and isoflavones only display Band II absorption (269–279 nm). Anthocyanidins may be easily identified by their Band I absorption between 460 and 550 nm in the visible range, in contrast to flavonols and flavones, which exhibit Band I absorption between 300 and 380 nm [72]. **Figure 6** provides typical illustrations of the UV–Vis absorbance spectra of the major groups of flavonoids.

#### **Figure 6.** *UV–vis absorbance spectra of the principal classes of flavonoids: (a) Luteolin [73]; (b) quercetin [74].*

**Figure 7.** *HPLC–UV at 260 nm (a), 1 and 2 represent UV spectra of peak 7 (hispidol 40-O-glucoside) and peak 34 (afrormosin), respectively [75].*

In research by Mohamed A. Farag et al., an integrated approach utilizing HPLC– UV was used for the large-scale and systematic identification of polyphenols in *Medicago truncatula* root and cell culture. UV spectra (200–600 nm) were recorded for different flavonoid sub-classes including 26 isoflavones (peaks 1–6, 8, 10, 12, 14, 19–29, and 31–35), 4 flavones (peaks 9, 13, 18, and 31), 2 flavanones (peaks 21 and 30), 2 aurones (peaks 7 and 11), and a chalcone (peak 32) with isoflavone representing the major sub-class. For example, isoflavones typically have a maximum absorbance near 255 nm with a second maximum between 300 and 330 nm (peak 34 in **Figure 7**), whereas aurones have the first maximum near 250 nm and the second peak around 390 nm (peak 7 in **Figure 7**) [75].

Kim-Ngan Huynh Nguyen et al.'s study quantified seven major compounds, including phenolic acids (chlorogenic acid, caffeic acid, and p-coumaric acid) and flavonoids (rutin, quercitrin, quercetin, and kaempferol) in three aerial parts of *Physalis angulata*, that is, leaves, calyces, and fruits. Chromatographic separation was carried out on a Kromasil C18 column (150 mm × 4.6 mm i.d., 5 μm) with a gradient elution of 0.1% formic acid in acetonitrile, 0.2% ammonium acetate/0.1% formic acid in water and methanol at a flow rate of 1.0 mL/min; detection was at 250 and 300 nm. The applications of liquid chromatography (LC) with ultraviolet (UV) for the analysis of flavonoid metabolism of plants that show in **Table 1** (**Figure 8**) [81].

#### **3.2 Liquid chromatography (LC) with mass spectrometry (MS)**

In contrast to 30 years ago, routine separation and preliminary identification of complex mixtures of flavonoids ranging over many orders of magnitude in concentration are now achievable because of the combination of chromatographic resolution offered by HPLC and structural data offered by MS. Furthermore, during the past 10 years, significant advancements in LC technology have been realized. UHPLC (ultra-high pressure liquid chromatography), alternative stationary phases including monoliths and superficially porous phases, high-temperature HPLC [82, 83], and multidimensional HPLC [84–87] are a few noteworthy advancements.

Cheminformatics methods combined with LC-MS/MS provide a potent tool for high-throughput surveys of flavonoid variety [88, 89]. Utilizing straightforward solvent combinations and LC columns, glycosylated, acylated, and prenylated flavonoid molecules and their aglycones may be separated. For MS/MS analysis, the isolated

*Application of Liquid Chromatography in the Analysis of Flavonoid Metabolism in Plant DOI: http://dx.doi.org/10.5772/intechopen.107182*

#### **Table 1.**

*Applications of liquid chromatography (LC) with ultraviolet (UV) for the analysis of flavonoid metabolism.*

molecules are ionized next. In order to analyze flavonoids, LC-tandem mass spectrometry (LC-MS/MS) has emerged as the method of choice. Algae had previously been thought to have no flavonoids. But using an LC-MS/MS technique, flavonoids were identified as intermediates and end products, demonstrating the occurrence of flavonoid production in microalgae [90]. It implies that the undiscovered flavonoids in every plant species can be discovered using cutting-edge metabolomics technology.

With an emphasis on general ionization and fragmentation processes, a brief overview of the underlying knowledge pertinent to the MS detection and MS/MS structural elucidation of flavonoids will be provided in this part. Additionally, specialized research reports provide much more in-depth information on particular classes of flavonoids, including dihydroflavonols [91], isoflavones [92], flavone-di-C-glycosides [93], flavonoid-aglycones [94], flavonoid-O-glycosides [95], and flavonoid glycosides [96]. The discussion that follows will be restricted to the API sources electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure chemical ionization, which are presently the most pertinent LC-MS

#### **Figure 8.**

*HPLC chromatogram of the mixed standards solution (a), P. angulata leaves (b). P1–P13: Phenolic acids, including P4: Chlorogenic acid, P6: Caffeic acid, and P8: p-coumaric acid. F1–F9: Flavonoids, including F4: Rutin and F9: Quercetin [81].*

ionization sources (APPI). The applications of liquid chromatography (LC) with mass spectrometry (MS) to the analysis of flavonoid metabolism are shown in **Table 2**.

Shoucuang Wang et al. (2017) researched comprehensive profiling of metabolites in citrus fruits. Non-targeted high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS/MS) was used to profile the metabolites in fruit tissues. As a result, 7416 metabolic signals were detected. In addition to those reported metabolites, seven O-glycosylpolymethoxylated flavonoids were newly annotated in the study. To better characterize these flavonoids, the 3′,4′,5,6,7,8-hexamethoxyflavone standard (m70, RT 15.3 min, m/z 403.1389, error − 0.5 ppm) was analyzed first. The precursor ions of the standard compound lost one to four methyl radicals in the MS/MS spectrum to form the base peaks of [M + H - 15]+, [M + H - 30]+, [M + H - 45]+, or [M + H - 60] + (**Figure 9A**). The characteristic loss of 162 Da was observed in the MS/MS spectra corresponding to the dissociation of a hexose moiety and a series of methyl loss of the diagnostic fragments of 15 and 30 Da (**Figure 9B**–**D**) [102].

Paola Montoro et al. (2012) researched the metabolic profiles of different extracts (obtained by petals, stamens, and flowers) by LC-ESI-IT MS (liquid chromatography coupled with electrospray mass spectrometry equipped with an ion trap analyzer). MS/MS experiments were diagnostic for the identification of specific fragmentation patterns, that is, sugar loss for flavonoid O-glycosides or the loss of specific esterification units. Interpretation of the ESI-MS/MS experiment obtained by the analysis of *Crocus sativus* petals extracts allowed us to tentatively identify 31 flavon derivatives in the extracts under investigation, mainly glycosidated and metoxilated derivatives of kaempferol, quercetin, isorhamnetin, and tamaryxetin (**Figure 10**) [103].

#### **3.3 High-performance liquid chromatography in chiral flavonoid**

Enantiomer separation, resolution, and analysis have traditionally been achieved by the transitory or covalent synthesis of diastereoisomers. Diastereoisomers can be separated on an achiral chromatographic column by differential contact and retention because they have distinct physicochemical characteristics in an achiral environment. On a chemically bonded chiral stationary phase (CSP) with an achiral mobile phase,

*Application of Liquid Chromatography in the Analysis of Flavonoid Metabolism in Plant DOI: http://dx.doi.org/10.5772/intechopen.107182*

#### **Table 2.**

*Applications of liquid chromatography (LC) with mass spectrometry (MS) for the analysis of flavonoid metabolism.*

racemic flavonoid resolution has typically been achieved through chromatographic enantiospecific resolution through transient production of diastereoisomers.

In 1980, one of the earliest publications on flavanone glycoside HPLC separation appeared. Both naringin and narirutin may be acetylated using an equal mixture of pyridine and acetic anhydride and then resolved at low temperatures (between 0 and 5 OC) [104]. Prunus callus (sweet cherries), oranges, and grapefruit's prunin (naringenin-7-O-glucoside) epimers were initially separated in the middle of the 1980s using benzoylated derivatives [105]. On Cyclobond I columns, the separation of

#### **Figure 9.**

*Mass spectra and structures of polymethoxylated flavonoids glycosides in citrus. (A) 3, 4, 5, 6, 7,8-hexamethoxyflavone (m070). (B) Dihydroxy-trimethoxyflavone -O-hexoside (m117). (C) Hydroxytetramethoxyflavone-O-hexoside (m119). (D) Monohydroxy-hexamethoxyflavone-O-hexoside (m133). PMFs, DFI, diagnostic fragment ions of polymethoxylated flavonoids [102].*

prunin benzoate and naringin benzoate has also been shown. Naringenin derivatization to naringenin tribenzoate and separation on a Chiralcel OD column are also mentioned in the literature. Naringenin's hydroxyl groups may prevent chiral identification in this stationary phase as the enantiomers could not be resolved [34].

The main advantage of chiral separation methods over achiral methods is a better understanding of the pharmacokinetics of flavanones and the development of effective dosing regimens. In the case of racemic flavanones or stereochemically pure flavanones, this requires knowledge of the *in vivo* behavior of the enantiomers and epimers. During the drug development process, understanding and comprehending the conformational stability of chiral compounds may have a significant influence on the pharmacological, pharmacokinetic, and pharmacodynamic data. Using stereospecific analytical techniques, racemization and enantiomerization/epimerization may be studied. Rapid interconversion *in vivo* would eliminate any potential distinctions in the enantiomers' medicinal or harmful effects, making the synthesis of stereochemically pure enantiomers useless. Chirality must be taken into account from the beginning of the development process for stereochemically pure compounds and racemates [34].

In a study by Gaggeri R et al. (2011), the HPLC enantioselective separation of (R/S)-naringenin (**Figure 11**), a chiral flavonoid found in several fruits juices and well-known for its beneficial health-related properties, including antioxidant, anti-inflammatory, cancer chemopreventive, immunomodulating and antimicrobial *Application of Liquid Chromatography in the Analysis of Flavonoid Metabolism in Plant DOI: http://dx.doi.org/10.5772/intechopen.107182*

#### **Figure 10.**

*LC-ESI-MS. TIC and reconstructed ion chromatograms for Crocins qualitative analysis in H2O/EtOH extract of Crocus sativus petals [103].*

activities, has been performed on both analytical and (semi)-preparative scale using amylose-derived Chiralpak AD chiral stationary phase (CSP). A standard screening protocol for cellulose and amylose-based CSPs was firstly applied to analytical Chiralcel OD-H and Chiralpak AD-H, as well as to Lux Cellulose-1, Lux Cellulose-2, and Lux Amylose-2 in order to identify the best experimental condition for the subsequent scaling-up. Using Chiralpak AD-H and eluting with pure methanol (without acidic or basic additives), relatively short retention times, high enantioselectivity, and good resolution (Rs = 3.48) were observed. Therefore, these experimental conditions were properly scaled up to (semi)-preparative scale using both a prepacked Regispack column and a Chiralpak AD column packed in-house with bulk CSP [106].

### **4. Conclusion**

Many beneficial health effects have been attributed to flavonoids, which are popular in the plant. The study of metabolism and bioavailability is very important in defining the pharmacological and toxicological profile of these flavonoid compounds. Due to great structural diversity among flavonoids, these profiles differ greatly from one compound to another, so the most abundant polyphenols in our diet are not necessarily the ones that reach target tissues. Therefore, careful analysis of flavonoids and their metabolites in biological systems is critical. Several hundred papers on the HPLC of flavonoids have been published in the past 20 or so years, yet HPLC methods can detect flavonoids across one, two, or perhaps three subclasses in one run. The improvements in HPLC flavonoid analysis closely resemble and, to a certain extent, build on those in domains like proteomics and metabolomics, which are supported by important breakthroughs.


**1. Introduction**

Chronic kidney disease has become a significant public health concern. Nephrotic syndrome (NS) is a special type of chronic kidney disease, which could be caused by a variety of factors. It is characterized by heavy proteinuria (more than 3.5 g/d), hypoalbuminemia, and edema [1]. Affected patients without effective treatment will in time develop end-stage renal disease. The adriamycin-induced nephrotic syndrome, which was first reported by Bertani et al. in 1982, is a classical nephrotic syndrome model [2]. Adriamycin is a quinone-containing anthracycline antibiotic and can be reduced to a semiquinone radical by metabolism in the kidney. The latter reacts with oxygen to produce reactive oxygen, inducing lipid peroxidation in the glomerular epithelial cells and destruction of the structure and function of the filtration membrane, and leading to progressive and irreversible proteinuria, hypoalbuminemia and hyperlipidemia [3]. An acute adriamycin-induced nephropathy model is induced by a single tail vein injection of 5–7.5 mg/kg adriamycin. This model, similar to human minimal change nephrotic syndrome, has been well characterized as an experimental model for nephrotic syndrome [4].

Treatment of nephrotic syndrome can slow its progression to end-stage renal disease. However, the therapies of nephrotic syndrome remain limited [5]. Many clinical and experimental studies have shown that the pathogenesis of nephrotic syndrome is associated with immune dysfunction. Immunosuppressive treatment, including corticosteroids, is the first-line treatment for nephrotic syndrome [6]. However, steroid resistance or steroid dependence is very common and frequently causes immune dysfunction and complicated infection, leading to end-stage renal failure [7]. Therefore identification of effective and less toxic therapeutic interventions for nephrotic syndrome remains to be an important issue.

The brown seaweed, *Saccharina japonica*, is a common seafood in China and Japan. It was documented as a traditional herb in traditional Chinese medicine for over a thousand years. The hot-water decoction of *S. japonica* is orally administered solely or combined with other herb extracts, and used for treatment of edema, a symptom of renal disease. Based on its therapeutic effect, our previous studies revealed that fucoidan, the water-soluble sulfated fucose-containing polysaccharide from *S. japonica*, was the main active component to treat edema. Fucoidan from *S. japonica* had renoprotective effect on chronic renal failure, diabetic nephropathy and acute kidney disease [8–11]. Nephrotic syndrome is a special type of chronic kidney disease, whether fucoidan have protective effect on nephrotic syndrome is still unclear.

As reviewed by Berteau and Mulloy [12], algal fucoidan represents a rather heterogeneous group of sulfated polysaccharides with complex and heterogeneous structures devoid of regularity. The structure of fucoidan extracted from *S. japonica* was much more complicated [13]. Its backbone was primarily consisted of (1→3)-linked-α-L-fucopyranose residues and a few (1→4)-α-L-fucopyranose linkages. The branch points were at C-4 of 3-linked -α-L-fucopyranose residues by β-D-galactopyranose unites or at C-2 of 3-linked -α-L-fucopyranose residues by non-reducing terminal fucose units. Sulfate groups occupied at position C-4 or C-2, sometimes C-2, 4 to fucose residues, and C-3 and/or C-4 to galactose residues. Besides fucose, fucoidan from *S. japonica* also contains minor galactose, mannose, glucose, rhamnose, and xylose. Fucoidans have been reported to have diverse bioactivities, such as antioxidant [14], anti-inflammatory [15], reno-protective [8], antitumor [16], and anticoagulant [17] activities. The molecular weight has been demonstrated to play an important role in the biological activities of polysaccharides. Comparing with unfractioned heparin, low-molecular-weight heparin has improved bio-availability, a longer half-life, and more predictable dose response, which make their use increasing common in the treatment and prophylaxis [18]. The relationship between molecular weight and bioactivities of fucoidan was reported in recent years. A low-molecular-weight fucan fraction extracted from the brown seaweed *Ascophyllum nodosum* exhibited dose-related venous antithrombotic activity [19]. A high level of inhibitory activity on complement can be achieved with low-molecular-weight fucoidan molecules [20]. If fucoidans with different molecular weight have a different effect on nephrotic syndrome still needs investigation.

In this study, we isolated a fucoidan from *S. japonica* and prepared its depolymerized fragment by oxidant degradation. The effect of fucoidan and its depolymerized fragment on adriamycin-induced nephrotic syndrome were investigated in a rat model.


**4. Summary and conclusions**

This chapter introduces a novel concept for impulsive interference management in low power, autonomous, IR-UWB networks. The concept enables concurrent transmissions at full power, while allowing each source to independently adapt its pulse rate (measured in pulses per second) to reduce the impact of pulse collisions at nearby receivers. The design is independent of a particular modulation scheme and can be applied to any IR-UWB physical layer. Beyond, it does not rely on any particular receiver technique and can work with a simple, low cost, non-coherent receiver.

The chapter formulates and evaluates the pulse rate allocation problem as a social rate optimisation problem with QoS constraints. It introduces a distributed algorithm implementation and analyses its performance via simulation. It has been analytically proven that the game ΓPRC fits the framework of ordinal potential games, and that the NE is unique. In all considered scenarios, simulation results have confirmed the existence of an equilibrium for the game and that the distributed PRC algorithm converges to it, provided that the pricing parameters have been appropriately chosen.

We can conclude that distributed Pulse Rate Control is an appropriate means for impulsive interference management and network throughput optimisation with QoS constraints in highly loaded IR-UWB networks with a common central receiver. In [16] the author extends the work presented here and investigates the applicability of distributed PRC as well as its combination with adaptive channel coding in peer-to-peer networks, i.e. with multiple uncoordinated receivers and without any hierarchical infrastructure. Moreover she investigates a low-complexity, heuristic, alternative algorithm to the one proposed in this chapter that is more suitable for embedded hardware implementations, as preferred in the design of sensor networks.


*2.1.3 Spray metal tooling*

Metal spray molds had been used effectively in low-pressure procedures including RIM, vacuum forming, and rotational molding. Currently, the improvements in spray metals and spraying methods give rise to its use in injection molding.

The order of steps is like the one applied to manufacture epoxy molds, with the exception that the pattern is sprayed first with metal and then supported by epoxy resin filled with metal. The process of spraying with, for example, an electrical compressed air gun gets applied until the required shell thickness is met (0.5 mm + − mm is reported). In this technique, the material consisting of pattern must have increased strength and durability to withstand the thermal impact inherent: in this regard, the use of ABS FDM masters, polycarbonate SLS masters, and machinable wax gave positive results some of the indirect methods which uses AM, and their advantages and disadvantages are shown in **Table 2**. In addition to them,

#### **Table 2.**

*Advantages and disadvantages of indirect methods, which use AM.*

**93**

*Utilization of Additive Manufacturing to Produce Tools DOI: http://dx.doi.org/10.5772/intechopen.89804*

spray metal tooling depicted in **Figure 2** [6].

**2.2 Direct methods of rapid tooling**

injection molding by up to 40% [6].

going on in order to increase its applicability [6].

SLS process can be seen in **Figure 3** [6].

*2.2.3 Copper polyamide tooling*

*2.2.1 Direct AIM*

*2.2.2 SLS RapidSteel*

a reflective coating could be protective. Also, SLA models were tried process of the

All the past AM techniques mentioned include indirect production of a master model producing the tool. The time required to manufacture and complete its pattern is one of the major issues with the manufacturing tool. Moreover, such replication methods can still cause increase in inaccuracies. As a result, although the most of direct tooling techniques have constraints, corporations ask directly produced tooling. Applying additive "layer manufacturing" methods, further properties may get included in the item, which cannot be acquired with conventional tooling techniques. Conformal heating (or cooling) channels provide the system with the ability to heat or cool the exact points needed, and it is the most critical property of it. It is shown that conformal channels could result with the reduction in cycle times of

Rather than making a master stereolithography pattern around which a material is cast, it also is possible to build the cavity directly on the stereolithography machine. This method has been described as Direct AIM by 3D Systems (Valencia, CA). (AIM stands for ACES Injection Molding. ACES stands for "accurate clear epoxy solid," which is a stereolithography construction style.) Even though they are not as strong or difficult as standard tools, various thermoplastics can get injected into those cavities so that elements to get used could get manufactured. Even though only less abrasive and lower melting polymers can get molded, studies are

Just as a cavity can be produced directly by stereolithography, the laser sintering method can also be used to construct tool cavities directly. Digital core and cavity geometry models are developed and sent to a Sinterstation manufacturing device in RapidSteel powder with DTM's RapidSteel (also known as RapidTool, earlier similar methods are known as Indirect Metal Selective Laser Sintering). This material comprises of mild stainless-steel particles that are covered with a thin layer of a material for a polymer binder. The Sinterstation generates green components that fire in a furnace afterwards. The furnace removes the polymer binder and by capillary action infiltrates bronze into the inserts of the mold. This method generates a completely thick tool consisting of approximately 60% steel and 40% bronze. Then the inserts are completed, drilled for ejector pins, and fitted to the base of the mold. The technique generates a durable mold that can be used as well as die-casting apps for injection mold tooling. Hundreds of aluminum, zinc, and magnesium components were casted using RapidSteel molds. The technique enables complicated geometries, and molds from RapidSteel can resist injection molding circumstances. RapidSteel, however, needs finishing and polishing that can take time scheme of the

The DTM (Austin, Texas) copper polyamide tooling method is consisted of selective laser sintering of a matrix of copper and polyamide powder to manufacture

**Figure 2.** *Spray metal tooling [7].*

a reflective coating could be protective. Also, SLA models were tried process of the spray metal tooling depicted in **Figure 2** [6].


**Author details**

Tamás Sági1 \*, Szabolcs Harangi1 and Theodoros Ntaflos2

1 Department of Petrology and Geochemistry, Budapest, Hungary and MTA-ELTE Volcanology Research Group, Eötvös Loránd University, Budapest, Hungary

2 Department of Lithospheric Research, University of Vienna, Vienna, Austria

\*Address all correspondence to<EMAIL_ADDRESS>
© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Modeling of Olivine and Clinopyroxene Fractionation in Intracontinental Alkaline Basalts… DOI: http://dx.doi.org/10.5772/intechopen.94808*


**Author details**

Takeo Oku\* , Masahito Zushi, Kohei Suzuki, Yuya Ohishi, Taisuke Matsumoto and Atsushi Suzuki

\*Address all correspondence to<EMAIL_ADDRESS>
Department of Materials Science, The University of Shiga Prefecture, Hikone, Shiga, Japan


*Article* **Spatial Form and Conservation Strategy of Sishengci Historic District in Chengdu, China**

**Wen Liang, Yahaya Ahmad \* and Hazrina Haja Bava Mohidin**

Faculty of Built Environment, University of Malaya, Kuala Lumpur 50603, Malaysia

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +60-379-675395

**Abstract:** The historic district is a carrier to show the urban landscape, and the analysis of the spatial form of the historic district from human behavioral activities is beneficial to grasp the social and functional attributes of the space. Combining with the spatial layout of the Sishengci historic district, the overall spatial structure of the Sishengci historic district is analyzed in terms of integration, connectivity, control, depth, and intelligibility by using the analysis of the axial lines in space syntax through the relationship diagram and quantitative description of the syntax. Based on the findings, targeted conservation strategies are proposed, namely the conservation of the core area of the district, the shaping of the local spirit, and the reconstruction of the social space, which have a guiding significance for the conservation and renewal of the Sishengci historic district.

**Keywords:** historic district; spatial morphology; space syntax; conservation strategy