Waterlogging stress dramatically reduced the Chl content in the leaves of seedlings. After 9 days of waterlogging stress, the Chl content of these plants (2.4 mg/g FW) was only roughly half of the value of control seedlings (4.1 mg/g FW). The photosynthetic rate of the waterlogging stressed plants was 1.67 µmol·m−2 ·s −1 . The value was significantly lower than that of control seedlings (2.67 µmol·m−2 ·s −1 ). Melatonin treatments (spray or irrigation) improved both Chl content and photosynthetic rate which were suppressed by the waterlogging stress (**Figures 6A,B**).

### DISCUSSION

Waterlogging, caused by poor drainage, flooding, and long periods of rainfall, usually occurs in summer and autumn, which hampers apple tree growth and results in yield loss (Yu et al., 2015). Because of the global warming effect, it is predicted that this climate change will bring more rainfall yearly and thus

the waterlogging will be frequently encountered by the crops worldwide. This will bring severe problem for these crops which are intolerant to the waterlogging stress including the apple trees. To solve this problem, it has become an urgent agenda for scientist.

In the current study, a unique molecule, melatonin, was tested with this purpose. Melatonin was reported to enhance plant tolerance against various abiotic stressors including cold, hot, drought, salinity, and chemical pollutants (Bajwa et al., 2014; Wei et al., 2014; Liang et al., 2015; Liu et al., 2015; Shi et al., 2015b;

Li X. et al., 2016; Xu et al., 2016). But the effect of melatonin on waterlogging resistance is still to be investigated.

Long lasting waterlogging caused apple seedling damage. Under waterlogging, the seedlings changed their metabolism from aerobic to anaerobic respiration (Fukao and Bailey-Serres, 2004). During this transition, a burst of ROS was generated and this resulted in oxidative damage of the seedlings (Hossain et al., 2009; Xu et al., 2013; Takahashi et al., 2015). This was indicated by the phenotype alterations of the seedlings such as chlorosis and wilting (**Figure 1**). However, all these changes were partially or completely prevented by melatonin application either by spraying to the leaves or irrigating to the roots. The primary mechanism of melatonin to improve the tolerance of apple seedlings against waterlogging stress may relate its potent free radical scavenging and antioxidant capacity (Tan et al., 1993, 2012). Melatonin not only directly scavenges the ROS but also upregulates the activities of a variety of antioxidant enzymes (Wang et al., 2012). This was in accordance with our observations in the current study (**Figures 3, 5**).

In the current study, both waterlogging stress and melatonin application significantly increased melatonin level of the plants. It is well known that various stressors induce melatonin production in plants as well as in animals (Byeon et al., 2012; Li C. et al., 2016; Xu et al., 2016). This is considered as self-defense of organisms against external insults (Tan et al., 2015). Our observation provided new evidence to support this consideration. Waterlogging induced the gene expression of the melatonin synthetases and increased melatonin production in the apple seedlings. This positive response mechanism at the RNA level, for melatonin production in apple plants, probably also, exists in other plants. When exogenous melatonin was applied under waterlogging stress, the stress-induced expression of the melatonin synthetases still maintained their high expression. But obviously, the slight expression change between melatonin + waterlogging treatment and only waterlogging treatment can't explain the significant melatonin increase after exogenous melatonin applied under waterlogging. It seemed that melatonin absorbed from outside mainly resulted in melatonin increase. In addition, for the MbASMT9, a melatonin synthetic rate-limiting enzyme, which was located in chloroplasts (Kang et al., 2013; Zheng et al., 2017), its upregulated RNA expression did not result in elevated protein level. In contrast, its protein level reduced after melatonin application. This probably was the first report to document a post-transcriptional regulation of melatonin synthesis in plants. There are accumulated post-transcriptional regulation reported, including RNA processing, transport and degradation, translation control to fine-tune biological processes for plants in response to the environmental changes (Palatnik et al., 2003, 2007; Cowley et al., 2012; Saze et al., 2013). Obviously, herein, the post-transcriptional regulation conserves resources and energy of the plants to avoid extra melatonin production when exogenous applied melatonin meets their requirement. This observation provided valuable information as to use of exogenous melatonin to improve plant tolerance to against stressors.

There are accumulated reports described the waterlogging caused transition from aerobic to anaerobic respiration in root, which is also confirmed by us (**Figure 4**). Our results also uncovered the role of melatonin to maintain aerobic respiration under waterlogging stress, by efficient suppression of the ROS burst and subsequent mitochondria degradation. The chlorosis is a typical sign unavoidably happening after severe waterlogging. Due to the reason that waterlogging leads to water shortage and subsequent quick stomata closure, the high concentration of O2 can't be released out and photosynthetic electron transportation is blocked in chloroplasts. Therefore, the ion leakage from the electron transport chain would induce in over-produced O•− 2 and H2O2, which destroy chlorophyll and lead to the disintegration of chloroplasts (Musgrave, 1994; Smethurst and Shabala, 2003). The protective effects of melatonin on Chl decay, photosynthetic capacity and stomata configurations have been reported previously in other stressors such as in drought and hot (Wang et al., 2012; Xu et al., 2016). Actually, chloroplasts, as one of the most suffered organelles from ROS, were proved to be the major site for melatonin production. A large amount of melatonin is needed to maintain its structure and function. Therefore absorbed and in vivo synthesized melatonin can function together to migrate waterlogging induced ROS and help to survive the stress. Here we reported that melatonin application preserved the Chl content and maintained the photosynthetic rate in seedlings suffered from waterlogging stress. The high content of Chl and efficient photosynthesis are required for high yield of apple production (Li et al., 2000). It is our

speculation that melatonin application in the field will increase the tolerance of apple tree and reduces apple yield loss against waterlogging stress. The speculated mechanisms are summarized in **Figure 7**.

## AUTHOR CONTRIBUTIONS

Designed the studies: JK, Undertook the experimental work: XZ, JZ, NW, LW, and DS. Contributed to figures and manuscript preparation: XZ, D-XT, and JK. All authors read and approved the final manuscript.

### REFERENCES

### ACKNOWLEDGMENTS

This research was supported by Chinese Universities Scientific Fund (NCET13-0555) and the NSFC (National Natural Science Research Foundation of China, Project No: 31372034).

### SUPPLEMENTARY MATERIAL

The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fpls.2017.00483/ full#supplementary-material

chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochim. Biophys. Acta 975, 384–394. doi: 10.1016/S0005-2728(89)80347-0

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2017 Zheng, Zhou, Tan, Wang, Wang, Shan and Kong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.


**(CHIP) Digital Health Census, Longitudinal Primary Health Follow-Up, and Disease Surveillance Through a Unified Mobile Platform**

#### **Hemant Sharma**

Development Lead, Udaipur, India

In a vast country like India, with a 65% rural population, it is difficult to not only track disease spread but also to share health awareness and state-specific guidelines. Screening, testing, contact tracing, and quarantining are especially difficult in areas with low literacy and sociodemographic barriers.

Further, the current data collection system is paper-based, and communication is established as a hierarchy,

from the block to the district to the state. This data are shared via Excel sheets, so it remains difficult to obtain information in real-time and take action in a timely manner. Khushi Baby's CHIP platform is not only disrupting this paper-based tracking system but also digitally empowering Community Health Workers (CHWs). It includes a complete authenticated digital health census through door-to-door surveys by CHWs in Rajasthan. The USP of the platform includes:

Post the platform's launch in July 2020, more than 63,000 Community Health Workers used it to screen more than 14 million residents with 94,000 referrals and 31,000+ follow-ups. The Government of India recognized the platform as a finalist in the Strengthening COWIN Grand Challenge in May 2021.

In the last two months since the relaunch, an additional 3 million residents have been enrolled through the digital health census, and had their social determinants of health, reported health conditions, and COVID-19 vaccination status updated through CHIP. Given our ongoing role as the Nodal Technical Support Partner in Rajasthan and the integration of our platforms within the state's health infrastructure, we are well poised to meaningfully continue to contribute to pandemic preparedness in India.

Hemant Sharma

Development Lead, Udaipur, India

#### Problem Statement

India has the world's largest public health workforce, with over 1M ASHAs (village health volunteers) working under India's National 250K ANMs (Auxiliary Nurse Midwives), women in their 20s to 40s, caring for over 900M residents living in rural communities. Time saved from paper-based and fragmented digital reporting could be used to serve over 20M more beneficiaries on a monthly basis, to generate an accurate population denominator, to ensure longitudinal care follow-up, and to identify the community spread of disease easily.

#### Solution

Khushi Baby looks to address the above challenges with CHIP ("Community Health Integrated Platform"), a digital public health system, which is currently being scaled across Rajasthan, India's biggest state.

CHIP includes offine-ready m-health applications for the three key health workers of the Indian public health system: the ASHA (village health volunteers), the ANM (nurse, who visits the community once a month for preventative checkups), and the Medical Officer (who cares for high-risk patients).

These mobile applications capture the entire work requirement of each respective health worker, across all primary health care programs. This streamlines data collection, report generation, and payment automation. These mobile applications are also inter-linked, allowing longitudinal beneficiary data for informed care to be shared. Using the platform, health workers will be able to perform the following core activities from their smartphone:

1.A digital health census to capture the true population denominator (which has been a challenge) and community health need;

2.Longitudinal follow-up of primary health care across program verticals (e.g., family planning, maternal and child health, non-communicable diseases, tuberculosis);

3.Disease outbreak surveillance for COVID-19 and other emerging infectious diseases (including symptom-screenings, referrals, and vaccination follow-up).

This platform also digitally empowers health officials with AI and GIS-based dashboards to a) monitor and respond to community needs in real time, b) monitor and respond to healthcare performance in real time, and c) automate personalized community engagement for health workers and beneficiaries.


**2. Method of Determining the Resistance of Fillet Welds**

Welded joints made of hollow sections should be made using fillet or butt welds, or combination of the two, laid on the perimeter of the profile. In overlapped joints, the covered part of the member need not be welded, when the components of axial forces in the brace members perpendicular to the chord axis do not differ by more than 20% [18].

According to Dexter and Lee [19], the resistance of the overlapped CHS joints with the hidden part welded was about 10% higher.

To simplify the calculation of the welds in hollow section structures European standard recommends the design of the welds in such a way, that the weld resistance per unit length of the member perimeter should not be less than the resistance of that member also calculated per unit length of perimeter. This condition is met when butt or fillet welds which are used have such thickness, that their resistance is equal to the resistance of connected members. Methods of estimating the thickness of fillet welds that meet this requirement are given in [16].

The European standard [20] suggests, in cases where the design of a full butt weld or the adequate fillet weld is not required, that the thickness of the weld may be reduced, on condition that the resistance of such weld and its rotation capacity are checked, considering only the weld effective lengths.

In Figure 1, using the IIW guidance [13] the layout of fillet welds in the K-type overlapped joint between the RHS braces and the H chord is shown. An assumption was made that the value of the component force perpendicular to the chord transferred directly through the welds connecting the brace members is equal to (Figure 1a):

$$\begin{aligned} \Delta K\_i &= \alpha K\_i \sin \theta\_i \text{ when } 25\% \le \lambda\_{\text{av}} \le 80\%, \\ \Delta K\_i &= K\_i \sin \theta\_i \text{ when } \lambda\_{\text{av}} > 100\%. \end{aligned} \tag{1}$$

where α = *q*/*p* and 0.25 ≤ α ≤ 0.80, λ*ov* = (*q*/*p*) · 100% in %, *q*—the overlapping surface of braces projected on the face of the chord, *p*—length of contact area between the overlapping brace and the chord (the procedure of assessment of welds resistance in K-type joints made of hollow section is presented in [21]).

**Figure 1.** The connection of hollow section brace members to I- or H-section chords: (**a**) The standard joint: (**b**) The layout of fillet welds joining the rectangular hollow section (RHS) braces to the H chords when 25% ≤ λ*ov* ≤ 80% and the hidden part of the connection is welded; (**c**) the layout of fillet welds joining the RHS braces to the H chords when 25% ≤ λ*ov* ≤ 80% and the hidden part of the connection does not have to be welded; (**d**) layout of fillet welds joining the RHS braces to the H chords when λ*ov* > 100%.

The remaining part of the load component perpendicular to the chord is

$$\begin{aligned} redd\Delta K\_j &= K\_j \sin \theta\_j - \alpha K\_l \sin \theta\_l \text{ when } 25\% \le \lambda\_{\text{OV}} \le 80\%\_\prime\\ redd\Delta K\_j &= K\_j \sin \theta\_j - K\_l \sin \theta\_l \text{ when } \lambda\_{\text{OV}} > 100\%\_\prime\\ redd\Delta K\_j &= 0 \text{ in the case of no external load applied to the joint.} \end{aligned} \tag{2}$$

The values of effective lengths of welds are determined as follows (Figure 2):

**Figure 2.** Effective lengths of welds: (**a**) the layout of fillet welds joining the RHS braces to the H chords when 25% ≤ λ*ov* ≤ 80% and the hidden part of the connection is welded; (**b**) the layout of fillet welds joining the RHS braces to the H chords when 25% ≤ λ*ov* ≤ 80% and the hidden part of the connection is not welded; (**c**) the layout of fillet welds joining the RHS braces to the H chords when λ*ov* > 100%; (**d**) welds between the braces in the case of the partial overlap; (**e**) welds between the braces in the case of the full overlap.

1. In connections of braces with the flange of the chord (Figure 2a–c):

$$\begin{aligned} l\_1 &= h\_j / \sin \theta\_{j\prime} \quad b\_{j,rad} = b\_j - 2a\_{w\prime} \\ l\_2 &= p\_{j\varepsilon f\prime} = t\_w + 2r + \mathcal{T}t\_f f\_{y0} / f\_{yj\prime} \text{ but } p\_{j\varepsilon f\prime} \le b\_{j\prime} \end{aligned}$$

$$\begin{aligned} l\_3 &= h\_{i,rad} / \sin \theta\_{i} = (1 - \alpha)h\_i / \sin \theta\_{i\prime} \\ l\_4 &= p\_{i\varepsilon f\prime} = t\_w + 2r + \mathcal{T}t\_f f\_{y0} / f\_{yj\prime} \text{ but } p\_{i\varepsilon f\prime} \le b\_i \end{aligned} \tag{3}$$

2. In the direct connection between braces (Figure 2d,e):

• In the case of the partial overlap:

$$l\_5 = \frac{q}{\left(1 + t g \theta\_j / t g \theta\_i \right) \cos \theta\_j}, \quad l\_6 = b\_i \tag{4}$$

• In the case of the complete overlap:

$$l\_7 = h\_i / \sin\left(\theta\_i + \theta\_j\right) \\ l\_6 = b\_i \tag{5}$$

where θ*i*, θ*j*—inclination angles of the overlapping and overlapped braces in relation to the chord, *fy0* —the yield strength of the chord, *bi*, *hi*—respectively, the width and the height of the section of the overlapping brace, *bj*, *hj*—respectively, the width and the height of the section of the overlapped brace, *ti*—the wall thickness of the overlapping brace, *tj*—the wall thickness of the overlapped brace, *tf*—the flange thickness of the I-section, *tw*—the web thickness of I-section, *r* the radius of the I-section.

Areas of cross-sections of effective lengths of welds are (Figure 1): *A*1 = *l*1*aw*1, *A*2 = *l*2*aw*2, *A*3 = *l*3*aw*3, *A*4 = *l*4*aw*4, *Aj*,*red* = *bj*,*redawb*, *A*5 = *l*5*aw*5,*A*6 = *l*6*aw*6, *A*7 = *l*7*aw*7, where *aw*1, *aw*2, *aw*3, *aw*4 *awb*, *aw*5, *aw*6—thicknesses of welds.

In the case of 25% ≤ λ*ov* ≤ 80% design situation, all welds are made (also in hidden part) in the place of the splice of braces with the chord. The sections of fillet welds are loaded by the component forces in braces parallel to the chord (Figure 3a).

**Figure 3.** Component loads in the welds of braces: (**a**) parallel to the chord; (**b**) perpendicular to the chord.

Loads for individual effective lengths are

$$P\_1 \,' = \left(K\_{\bar{j}} \cos \theta\_{\bar{j}} + K\_{\bar{i}} \cos \theta\_{\bar{i}}\right) A\_1 / \sum A\_{\prime} \tag{6a}$$

$$P\_2 \prime = \left(K\_j \cos \theta\_j + K\_i \cos \theta\_i\right) A\_2 \prime \sum A\_\prime \tag{6b}$$

$$P\_3 ' = \left(K\_{\dot{\jmath}} \cos \theta\_{\dot{\jmath}} + K\_{\dot{\imath}} \cos \theta\_{\dot{\imath}}\right) A\_3 / \sum A\_{\prime} \tag{6c}$$

$$P\_4{}^{\prime} = \left(K\_j \cos \theta\_j + K\_i \cos \theta\_i\right) A\_4 / \sum A\_{\prime} \tag{6d}$$

$$P\_b{}^{\prime} = \left(K\_{\bar{j}} \cos \theta\_{\bar{j}} + K\_{\bar{i}} \cos \theta\_{\bar{i}}\right) A\_{\bar{j}, \text{rad}} / \sum A\_{\prime} \tag{68}$$

where *Kj* and *Ki* are the designed axial loads acting respectively in overlapped and overlapping braces and

$$
\sum A = 2A\_1 + A\_2 + 2A\_3 + A\_4 + A\_{j, rad}.\tag{7}
$$

In the same design situation, the fillet weld sections are loaded by load components in braces perpendicular to the chord, as shown in Figure 3b. Forces loading effective lengths can be calculated based on equations:

$$P\_1'' = 0,\tag{8a}$$

$$P\_2^{\prime\prime} = red\Delta K\_{\circ} \cdot A\_2 / \left(A\_2 + A\_{\text{j.rad}}\right) \tag{8b}$$

$$P\_{\mathfrak{J}}^{\prime\prime} = (1 - \alpha)\Delta K\_{\mathfrak{i}} \cdot A\_{\mathfrak{J}} / (2A\_{\mathfrak{J}} + A\_{\mathfrak{4}}) ,\tag{8c}$$

$$P\_4' = (1 - \alpha)\Delta K\_i \cdot A\_4 / (2A\_3 + A\_4) \, \tag{8d}$$

$$P\_{\rm b}^{\prime\prime} = red\Delta K\_{\rm j} \cdot A\_{\rm j,red} / \left(A\_2 + A\_{\rm j,red}\right) \tag{8e}$$

Components of loads in welds directly between the braces, in the case of the partial overlap are determined from equations (Figure 2d):

• Loads parallel to the overlapped brace axis:

$$P\_{\mathbb{S}}' = \Delta \mathcal{K}\_{i} \cdot A\_{\mathbb{S}} \sin \theta\_{j} / (2A\_{\mathbb{S}} + A\_{\mathbb{6}}),\tag{9}$$

$$P\_6' = \Delta \mathcal{K}\_i \cdot A\_6 \sin \theta\_j / (2A\_5 + A\_6). \tag{10}$$

• Loads perpendicular to the overlapped brace axis:

$$P\_{\mathfrak{F}}^{\prime\prime} = \Delta K\_i \cdot A\_{\mathfrak{F}} \cos \theta\_j / (2A\_{\mathfrak{F}} + A\_{\mathfrak{G}}),\tag{11}$$

$$P\_{\theta}^{\prime\prime} = \Delta K\_i \cdot A\_6 \cos \theta\_j / (2A\_5 + A\_6). \tag{12}$$

Components of loads in welds directly between the braces, in the case of the full overlap are determined from equations (Figure 2e):

• Loads parallel to the overlapped brace axis:

$$P'\_6 = \Delta \mathcal{K}\_i \cdot A\_6 \sin \theta\_j / (2A\_6 + 2A\gamma),\tag{13}$$

$$P\_{\mathcal{T}}' = \Delta \mathbb{K}\_{i} \cdot A\_{\mathcal{T}} \sin \theta\_{\circ} / (2A\_{6} + 2A\_{7}). \tag{14}$$

• Loads perpendicular to the overlapped brace axis:

$$P\_{6}^{\prime\prime} = \Delta K\_{i} \cdot A\_{6} \cos \theta\_{j} / (2A\_{6} + 2A\_{7}) \tag{15}$$

$$P\_{7}^{\prime\prime} = \Delta K\_{\circ} \cdot A\_{7} \cos \theta\_{\circ} / (2A\_{6} + 2A\_{7}). \tag{16}$$

Stresses in welds caused by the force parallel to the chord at the partial overlap of 25% ≤ λ*ov* ≤ 80%: 1. In longitudinal welds (Figure 4a):

• In the case of welds placed by the overlapped brace's walls:

$$
\sigma' = 0,\ \sigma'\_{\perp} = \tau'\_{\perp} = 0,\ \tau'\_{II} = P'\_1 / \left(a\_{w1} \cdot l\_1\right). \tag{17}
$$

• In the case of welds placed by the overlapping brace's walls:

$$
\sigma' = 0,\ \sigma'\_{\perp} = \tau'\_{\perp} = 0,\ \tau'\_{II} = \mathcal{P}'\_3 / (a\_{w3} \cdot l\_3) \tag{18}
$$

**Figure 4.** Stresses in welds caused by the load parallel to the chord: (**a**) in longitudinal welds; (**b**) on the not fully cooperating overlapped brace's transverse length; (**c**) on the fully cooperating transverse length of the overlapped brace; (**d**) on the not fully cooperating transverse length of the overlapping brace.

2. On the not fully cooperating overlapped brace's transverse length (Figure 4b):

$$
\sigma' = \mathbf{P}'\_2 / (a\_{w2} l\_2), \ \sigma'\_{\perp} = \sigma' \sin(\theta\_j / 2), \ \tau'\_{\perp} = \sigma' \cos(\theta\_j / 2), \ \tau'\_{\Pi} = 0. \tag{19}
$$

3. On the fully cooperating transverse length of the overlapped brace (Figure 4c):

$$
\sigma \nu = \mathbf{P}'\_b / \left( a\_{wb} b\_{j,rd} \right), \ \sigma'\_{\perp} = \sigma' \cos \left( \theta\_j / 2 \right), \tau'\_{\perp} = \sigma' \sin \left( \theta\_j / 2 \right), \ \tau'\_{ll} = 0. \tag{20}
$$

4. On the not fully cooperating overlapping brace 's transverse length (Figure 4d):

$$
\sigma \nu = P\_4'/(a\_{w4}l\_4), \ \sigma\_\perp' = \sigma' \sin(\theta\_i/2), \ \tau\_\perp' = \sigma' \cos(\theta\_i/2), \ \tau\_{II}' = 0. \tag{21}
$$

Stresses in welds of load perpendicular to the chord at the partial overlap of 25% ≤ λ*ov* ≤ 80%: 1. In longitudinal welds (Figure 5a):

• In the case of welds placed by the walls of the overlapped brace:

$$
\sigma'' = \frac{P\_1 \prime}{a\_{w1} l\_1}, \; \sigma\_\perp \prime = \frac{\sigma \prime}{\sqrt{2}}, \tau\_\perp \prime = -\frac{\sigma \prime}{\sqrt{2}}, \tau\_{\parallel \parallel} \prime = 0. \tag{22}
$$

• I the case of welds placed by the walls of the overlapping brace:

, σ⊥-- = − σ--

σ-- = *P*3 --

√

, τ⊥-- = σ--

√

, τ*II*--

= 0. (23)

**Figure 5.** Stresses in welds of the load perpendicular to the chord: (**a**) in longitudinal welds; (**b**) on the not fully cooperating the overlapped brace's transverse weld; (**c**) on the fully cooperating the overlapped brace's transverse weld; (**d**) On the not fully cooperating the overlapping brace's transverse weld.

2. On the not fully cooperating the overlapped brace's transverse weld (Figure 5b):

$$
\sigma'' = \frac{P\_2''}{a\_{\text{w2}}!\_2}, \sigma\_\perp'' = -\sigma'' \cos \frac{\theta\_j}{2}, \tau\_\perp'' = \sigma'' \sin \frac{\theta\_j}{2}, \tau\_{II}'' = 0. \tag{24}
$$

3. On the fully cooperating the overlapped brace's transverse weld (Figure 5c):

$$
\sigma'' = \frac{P\_b \prime}{a\_{wb} b\_{j, rad}}, \sigma\_\perp \prime = \sigma \prime \cos \frac{\theta\_j}{2}, \tau\_\perp \prime = -\sigma \prime \sin \frac{\theta\_j}{2}, \tau\_\Pi \prime = 0. \tag{25}
$$

4. On the not fully cooperating the overlapping brace's transverse weld (Figure 5d):

$$
\sigma'' = \frac{P\_4 \prime}{a\_{\text{n4}} l\_4}, \; \sigma\_\perp \prime = -\sigma \prime \cos \frac{\theta\_\text{i}}{2}, \; \tau\_\perp \prime = \sigma \prime \sin \frac{\theta\_\text{i}}{2}, \; \tau\_{\text{II}} \prime = 0. \tag{26}
$$

Stresses in the welds made directly between the brace members at the partial overlap of 25% ≤ λ*ov* ≤ 80% from the force parallel to the overlapped brace axis:

1. In longitudinal welds (Figure 6a):

$$
\sigma' = 0, \ \sigma'\_{\perp} = \tau'\_{\perp} = 0, \ \tau\_{II}{}' = \frac{P\_5{}}{a\_{w5} l\_5}. \tag{27}
$$

**Figure 6.** Stresses in welds between the brace members from the force parallel to the overlapped brace: (**a**) in longitudinal welds; (**b**) in the fully cooperating transverse weld.

2. In the fully cooperating transverse weld (Figure 6b):

$$
\sigma' = \frac{\mathbf{P}\_6'}{a\_{\text{w}6} l\_6}, \\
\sigma\_\perp ' = -\sigma' \cos \frac{\theta\_\mathbf{i} + \theta\_\mathbf{j}}{2}, \\
\tau\_\perp ' = \sigma' \sin \frac{\theta\_\mathbf{i} + \theta\_\mathbf{j}}{2}, \\
\tau\_{\text{II}} ' = 0. \tag{28}
$$

Stresses in welds placed between the brace members at the partial overlap of 25% ≤ λ*ov* ≤ 80% from the force perpendicular to the overlapped brace:

1. In longitudinal welds (Figure 7a):

$$
\sigma'' = \frac{P\_{5''}}{a\_{w\overline{5}l5}}, \ \sigma\_\perp '' = -\frac{\sigma''}{\sqrt{2}}, \tau\_\perp '' = \frac{\sigma''}{\sqrt{2}}, \tau\_{ll'} '' = 0. \tag{29}
$$

**Figure 7.** Stresses in welds between the brace members from the force perpendicular to the overlapped brace: (**a**) in longitudinal welds; (**b**) in the fully cooperating transverse weld.

2. In the fully cooperating transverse weld (Figure 7b):

$$
\sigma'' = \frac{P\_6''}{a\_{w\theta} l\_6}, \; \sigma\_\perp'' = \sigma'' \cos \frac{\theta\_j + \theta\_i}{2}, \; \tau\_\perp'' = -\sigma'' \sin \frac{\theta\_j + \theta\_i}{2}, \; \tau\_{\text{II}}'' = 0. \tag{30}
$$

The procedure of checking of a design situation with the full overlap of braces λ*ov* = 100% is analogous. In that case, the stresses in the transverse weld located near the connection of the overlapped brace with the chord should be examined (Figure 8), using the loads expressed by the Equations (24) and (25). The components of stress are:

**Figure 8.** Stresses in the transverse weld with full overlap: (**a**) in the transverse weld from the force parallel to the overlapped brace; (**b**) in the transverse weld from the force perpendicular to the overlapped brace.

1. In the transverse weld from the force parallel to the overlapped brace (Figure 8a):

$$
\sigma' = \frac{P\_6 '}{a\_{w6} l\_6 '}, \\
\sigma\_\perp ' = -\sigma' \sin \frac{\theta\_j + \theta\_i}{2}, \\
\tau\_\perp ' = -\sigma'' \cos \frac{\theta\_j + \theta\_i}{2}, \\
\tau\_{II} ' = 0. \tag{31}
$$

2. In the transverse weld from the force perpendicular to the overlapped brace (Figure 8b):

$$
\sigma'' = \frac{P\_6''}{a\_{w6} l\_6}, \sigma\_\perp ' = -\sigma' \cos \frac{\theta\_j + \theta\_i}{2}, \tau\_\perp '' = \sigma'' \sin \frac{\theta\_j + \theta\_i}{2}, \tau\_{\Pi} '' = 0. \tag{32}
$$

The component stresses occurring in cross-section of the welds should be added using the formulas:

$$
\pi \mu = \pi\_{\ll}' + \pi\_{\ll}'' ; \sigma\_{\perp} = \sigma\_{\perp}' + \sigma\_{\perp}'' ; \pi\_{\perp} = \pi\_{\perp}' + \pi\_{\perp}''. \tag{33}
$$

Standardized formulas for checking the safety of fully or partially cooperating transverse and longitudinal welds are:

$$\left[\sigma\_{\perp}^{2} + 3\left(\tau\_{\perp}^{2} + \tau\_{II}^{2}\right)\right] \le f\_{\text{u}} / \left(\beta\_{\text{w}} \gamma\_{\text{M2}}\right),\tag{34}$$

$$
\sigma\_{\perp} \le 0.9 f\_{\text{u}} / \gamma\_{M2\nu} \tag{35}
$$

where: β*w*—the correlation coefficient, *fu*—the tensile strength of steel, γ*M*2 = 1.25—the safety factor.

### **3. Conclusions**

RHS joints are generally semi-rigid, mainly because of the preferred technologies for their production, i.e., the direct welding of members. It implements a significant load from braces to the relatively slender front walls of the chord. The basic information for calculating joint resistance is given in many standards and references, but European standards contain a general recommendation on the calculation of capacity of welded joints and do not provide detailed design guidelines. The information contained is random and concerns only Y, X, K, and N joints with the gap. Additionally, in the case of the K and N types of joints with partially overlapped brace members, there is no indication of how to calculate the capacity of welds between the members.

This paper presents the method of assessment of the welded K and N type overlapped joints between RHS brace members and I or H section chords. This method comprises determining the stress components in welds in different load cases based on their effective lengths.

### **Design Example:**

Check the resistance of welds of an overlap K joint with a chord made of HEB 120 and SHS braces (Figure 9). Steel grade of S355H, *fy* = 355 N/mm2, *fu* = 490 N/mm2. Chord: *h*0 = 120 mm, *bf* = 120 mm, *tw* = 6.5 mm, *tf* = 11.0 mm, *r* = 12.0 mm, *A*0 = 34.0 cm2, *Wpl.y,*0 = 165.2 cm3, *N*0 = −159.9 kN. Brace loaded with compressive force: *h*2 = 80 mm, *b*2 = 60 mm, *t*2 = 4 mm; *N*2*.Ed* = −136.1 kN. Brace loaded

with tension force: *h*1 = 60 mm, *b*1 = 50 mm, *t*1 = 3 mm, *N*1*.Ed* = + 103.2 kN. The angles: θ1 = 50.34◦ > 30◦, θ2 = 40.02◦ > 30◦ (sin θ1 = 0.7698, cos θ1 = 0.6382, sin θ2 = 0.6431, cos θ2 = 0.7658, sin (θ1 + θ2) 1.0). The overlapped transverse weld is done −*cs* = 2.

**Figure 9.** The overlap joint made of H-section chord and SHS braces.


*2.4. Characterization*

#### 2.4.1. Size, Polydispersity Index, and Zeta Potential

The synthesized conjugated NPs were characterized by a particle size analyzer (PSA) using Zetasizer Nano ZS90 (Malvern Instrumentations, Malvern, UK). Moreover, 50 μL NPs were dispensed in a cuvette and disseminated in a 950 μL DDW to measure the percentage intensity at 25 ◦C.

## 2.4.2. Fourier Transform Infrared (FTIR) Spectroscopy

At 80 ◦C under 0.4 bar, the particles were freeze-dried using a freeze-dryer (Christ, Germany). As a cryoprotectant, mannitol (10%) was utilized. With a fine powder of 5.0 mg, Fourier transform infrared (FTIR) spectroscopy was accomplished. At an average temperature between 4000 and 400 cm<sup>−</sup>1, FTIR spectra were documented using potassium bromide (KBr) in a 1:10 ratio with an AVATAR 370 FTIR (Therma Nicolet, San Jose, CA, USA). A graph pattern was employed to determine the ionic interaction between samples to measure mancozeb loading. Spectroscopic Tools, 2019 (Thomas St. (http://www.scienceand-fun.de/tools/, accessed on 7 September 2022) was used to evaluate the data.

#### 2.4.3. Transmission Electron Microscopy (TEM)

The TecnaiTM (FEI, Hillsboro, OR, USA) TEM was used to confirm the mancozeb loading. Before analysis, samples were placed in a water bath sonicator. A drop of diluted conjugated nanoparticles was placed on a carbon-coated copper grid, followed by roomtemperature air-drying. The photos were acquired using a 200 kV operational voltage using a facility from SAIF, AIIMS, New Delhi.

#### 2.4.4. Differential Scanning Calorimetry (DSC)

At LPU, Jalandhar's CIF facility, a 3.0 mg sample was utilized to make thermographs using a DSC 4000 System (Perkin Elmer, Waltham, MA, USA) with a heating and cooling rate of 10 ◦C/min. Samples were heated from 30 to 445 ◦C. Pure nitrogen gas (99.99%) was pumped into the system at a rate of 20 mL/min.

#### *2.5. In Vitro Study*

#### 2.5.1. Encapsulation Efficiency (EE) and Loading Capacity (LC)

The supernatant was collected in a sterile tube after the nanocomposites were centrifuged at 15,000 rpm for 35 min. NanoDrop2000c (Thermo Scientific, Wilmington, DE, USA) was used to acquire mancozeb in the supernatant at 290 nm using the supernatant of their equal blank-attached nanoparticles as simple adjustments. The following equation was used to compute the encapsulation efficiency (EE%):

Total mancozeb added-mancozeb in supernatant/total mancozeb added ×100 = Encapsulation efficiency (percentage).

The following equation was used to compute the loading capacity (LC%):

(Mass of mancozeb in CSGA conjugated NPs)/(Weight of CSGA conjugated NPs recovered) × 100 (1)

#### 2.5.2. Slow-Release Profile of Conjugated CSGA NPs

Mancozeb's in vitro release from CSGA-conjugated nanoparticles was derived via dialysis tubing (Hi-Media Ltd., Mumbai). A total of 10 mg of the sonicated nanocomposite was added to 1.0 mL of sterile phosphate-buffered saline, PBS (pH 7.2). This was dished in a dialysis membrane with closed clips at one end and immersed in 10 mL of the same PBS in separate tiny beakers. At 37 ◦C, it was incubated in a shaker at 160 rpm; 1.0 mL of phosphate-buffered saline was pipetted out of each beaker after predetermined intervals of time (30 min), and the same volume of buffer was supplied to each beaker. The absorbance of the resultant solution was measured at 290 nm to estimate the quantity of mancozeb in the buffer using the standard curve.

#### 2.5.3. Antimicrobial Activity

The impact of NPs on the mycelial growth of a specific pathogen was established using the mycelium inhibition technique on potato dextrose agar (PDA, 2%) with certain modifications [23]. To make the final concentration of conjugated nanoparticles as 0.5, 1.0, and 1.5 ppm, autoclaved potato dextrose agar medium (Hi-Media, Mumbai, India; temp. 40 ◦C) was placed onto separate sterile Petri plates (90 mm × 15 mm) and allowed to harden. A 5.0 mm mycelial disc was removed from a seven-day-old test pathogen culture and placed in the center of the test Petri dish, where it was incubated at 28 ± 1 ◦C under constant monitoring. Growth was measured after four days for three replications, and the treated plates were compared to the control plates (without nanocomposites) to calculate the percent suppression of mycelia by NPs using an earlier approach [24].

$$\text{dc} - \text{dt/dc } 100 = \text{percent inhibition} \tag{2}$$

where dc is the control mycelial diameter and dt is the mycelial treatment diameter.


**5. Management of DKA**

### **5.1. Goals of therapy**

**4.2. Diagnosis of DKA**

296 Type 1 Diabetes

trations [19].

for HHS include [20-22]:

**◦** serum bicarbonate >15 mmol/L

**◦** small ketonuria, absent to mild ketonemia

**◦** effective serum osmolality >320 mOsm/kg

difficult to demonstrate in the very young.

relative to body mass.

**◦** arterial pH >7.30

**◦** stupor or coma

in the emergency room. Examples of such are:

Although DKA is defined by the biochemical triad of ketonemia, hyperglycemia and acide‐ mia, several exceptions do exist which may provide a diagnostic dilemma for the physician

**• "Euglycemic ketoacidosis''**: Partially treated children and children who have consumed little or no carbohydrate may present rarely with mildly increased blood glucose concen‐

**• Absent or mild metabolic acidosis, ketonemia and ketonuria**: This may occur in the Hy‐ perglycemic Hyperosmolar State (HHS) or if the patient experiences severe vomiting

**•** Hyperglycemic hyperosmolar state (HHS), also referred to as hyperosmolar nonketotic coma, may occur in young patients withT2DM, but rarely in T1DM subjects. The criteria

It is important to recognize that overlap between the characteristic features of HHS and DKA may occur. Some patients with HHS, especially when there is very severe dehydration, have mild or moderate acidosis. Conversely, some children with T1DM may have features of HHS (severe hyperglycemia) if high carbohydrate containing beverages have been used

**•** Other diagnostic difficulties may be faced in the very young age such as the following [2]:

**◦** Polyuria, polydipsia and weight loss which are characteristic features of diabetes are

**◦** up to 70% of the young have DKA as a first presentation, hence, at presentation, dura‐ tion of DKA is usually longer, dehydration and acidosis are more severe, as young chil‐ dren have relatively higher basal metabolic rate, and a relatively large surface area

**•** Measurement of blood ß-hydroxybutyrate (ß -OHB) concentration, may not be available in all labs, besides, urine Ketone testing can be misleading due the following reasons [2,4]:

**◦** The used method does not detect the major ketone body B-hydroxybutyrate. (sodium nitroprusside only measures acetoacetate and acetone). Serum ß-OHB concentrations,

which may lead to alkalosis which can mask the present acidosis.

**◦** plasma glucose concentration >33.3 mmol/L (600 mg/dL)

to quench thirst and replace urinary losses prior to diagnosis [22].

Management of DKA should be mainly directed to correction of acidosis. Immediate aims of management include [1,4]:

#### **5.2. Place of management**

The child with DKA should receive care in a unit that has:

Children with severe DKA or those at high risk for cerebral edema should be treated in an intensive care unit (pediatric, if available) or in a unit that has equivalent resources and su‐ pervision, such as a children's ward specializing in diabetes care [4].

In a child with established diabetes, whose parents have been trained in sick day manage‐ ment, and who presents with mild DKA, can be managed in an outpatient health care facili‐ ty (e.g., emergency ward), provided an experienced diabetes team supervises the care [15].

*Emergency Assessment [23]*

**•** A peripheral intravenous (IV) catheter should be placed for convenient and painless re‐ petitive blood sampling. An arterial catheter may be necessary in some critically ill pa‐

Diabetic Ketoacidosis: Clinical Practice Guidelines

http://dx.doi.org/10.5772/53020

299

**•** Perform continuous electrocardiographic monitoring to assess T-waves for evidence of

**•** Catheterize the bladder if the child is unconscious or unable to void on demand (e.g., in‐

Meticulous monitoring of the patient's clinical and biochemical response to treatment is mandatory for timely adjustments in treatment as indicated by the patient's clinical or labo‐ ratory data. Documentation on a flow chart of hour-by-hour clinical observations, IV and or‐

**•** Hourly (or more frequently as indicated) vital signs (heart rate, respiratory rate, blood

**•** Hourly (or more frequently as indicated) neurological observations for warning signs and

**◦** change in neurological status (restlessness, irritability, increased drowsiness, inconti‐ nence) or specific neurologic signs (e.g., cranial nerve palsies, abnormal pupillary re‐

**•** Hourly (or more frequently as indicated) accurate fluid input (including all oral fluid) and

**•** Capillary blood glucose should be measured hourly (but must be cross-checked against laboratory venous glucose, as capillary methods may be inaccurate in the presence of

**•** Give antibiotics to febrile patients after obtaining appropriate cultures of body fluids

**•** Give oxygen to patients with severe circulatory impairment or shock

**6. Further clinical and biochemical monitoring**

al medications, fluids, and laboratory results is very helpful.

Monitoring should include the following [4]:

**◦** inappropriate slowing of heart rate

poor peripheral circulation and acidosis).

symptoms of cerebral edema. The latter include:

pressure)

**◦** Headache

sponses)

output.

**◦** recurrence of vomiting

**◦** rising blood pressure

**◦** decreased oxygen saturation **•** Amount of administered insulin

tients managed in an intensive care unit.

fants and very ill young children)

hyper- or hypokalemia

*Biochemical assessment [1,4]*

	- **◦** Increased serum urea nitrogen and hematocrit may be useful markers of the severity of extracellular fluid (ECF) contraction.
	- **◦** It has to be noted that an elevated white blood cell count in response to stress is charac‐ teristic of DKA and is not necessarily indicative of infection [24].
	- **◦** Metabolic acidosis being an important landmark of DKA is also helpful to grade the se‐ verity of the condition and hence the prognosis by assessing its degree as follows [15]:

#### *Supportive measures [1]:*

**•** Secure the airway and empty the stomach by continuous nasogastric suction to prevent pulmonary aspiration, in case there is deterioration in conscious level.