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The current study investigated the effects of porosity, microstructure, and strain rate regime on the damage evolution and failure behavior under uniaxial compressive loading conditions in ice-templated alumina materials. The compressive response was investigated in dynamic and quasistatic loading regimes. Microstructural analysis revealed that in the high porosity regime, morphology was lamellar. In the lower porosity materials processed at higher freezing front velocities (FFVs), morphology was dendritic but transitioned to lamellar structure with the decreasing FFV. Ice-templated materials with higher porosity exhibited progressive crushing type damage evolution, irrespective of the FFV and strain rate regime. The origin of progressive crushing type failure was observed to be the absence of macroscopic crack evolution in the vicinity of peak stress, and subsequent to peak stress damage evolved only in the form of minimal fragmentation that gradually increased with the increasing strain. However, at comparable strain, the extent of dynamic damage was less compared to quasistatic damage, which suggests enhanced resistance to brittle fracture at high-strain rates. With the decreasing porosity damage evolution process changed, particularly under quasistatic loading in the materials processed at higher FFVs. Up to peak stress materials were intact, whereas upon reaching peak stress significant damage evolved causing complete loss of compressive load-bearing capacity. Whereas, damage evolution under dynamic loading in the vicinity of peak stress was significantly limited and damage accumulated progressively with the increasing strain, which strongly suggests greater structural stability in the ice-templated porous ceramic materials at high-strain rates.

This study investigated the compressive response of ice-templated composites and provides an understanding of their mechanical behavior based on the properties of templated ceramic and epoxy. Results suggested a dependence of properties on the microstructure of the templated porous ceramic, whereas more interestingly composites exhibited catastrophic and progressive types of failure. Compressive strength was found to be markedly greater relative to the strength of templated ceramic and polymer, and irrespective of the failure type, strength was greatly enhanced under dynamic loading relative to quasistatic loading. Compressive strength was also calculated based on the rule of mixtures and mode of failure in ice-templated ceramic. The analysis suggested that the axial mode of failure was not dominant in composites, and failures resulted from the fracture of lamella walls, possibly due to elastic instability. Fragments of the composite specimens were analyzed using scanning electron microscopy to study the fracture characteristics and rationalize the catastrophic and progressive types of failure.

We report the asymmetric synthesis of homochiral metal-organic materials (MOMs) in chiral gels from achiral components. The enantioselectivity of MOMs depends on the chirality of the gel, whereas the synthesis performed in solution phase and achiral gels resulted in conglomerates.

Lignocellulosic biomass is extensively present as cheap-cost recyclable resource on the globe. Lignocellulosic biomass transformation toward value-added biomolecules is the most sustainable approach as it is not competing with food chain or feed cycle. Lignocellulosic biomass conversion to value-added products is being carried out following various existing routes such as thermochemical, chemical, and or biological avenues. However, biological route of lignocellulosic biomass conversation via enzymes is one the most feasible, rapid, and ecological benign approach. Diverse range of microbial communities have been involved to secret various extracellular cellulase enzymes that degrade stubborn lignocellulosic biomass into simple carbon sources, which can further be converted into value-added products starting from biofuel to bioplastics. However, catalytic activities of these cellulases are not up to the mark that can support industrial need at present due to lower substrate specificity, substrate conversion rate, and turnover number. To this end, many experimental analysis have already been carried out to improve the bioprocess development for enhancing lignocellulosic biomass degradation through engineering (mutations and genetic engineering) intervention on cellulase enzymes. Hence, this chapter will depict a critical overview on current research activities toward ameliorating cellulase enzyme catalytic efficacy through mutational, genetic, and protein engineering approaches for lignocellulosic biomass conversation to value-added products.

The parabolic pulse (PP) generation within an optical fiber occurs in the presence of gain. The required amount of gain can be supplied either physically or virtually by suitably tapering the core radius throughout the length of the fiber. Regarding PP generation, designing a dispersion increasing fiber (DIF) is undesirable as it introduces negative gain within the fiber. In this work, we have developed a special kind of a dispersion increasing chalcogenide fiber (DICF) where the nonlinearity-induced virtual gain plays the dominant function. In spite of the role of dispersion in reducing the effective gain, an efficient PP is generated in a sufficiently shorter fiber length without supplying any physical gain due to the much more substantial contribution from the nonlinearity of the fiber.

Generation of a self-similar parabolic pulse (PP) in presence of virtually gained normal dispersion tapered chalcogenide fibers is presented in this work. The variations of group velocity dispersion and mainly nonlinearity along the fiber length produce the proposed nonlinearity varying chalcogenide fibers (NVCFs) which can induce sufficient amount of virtual gain leading to obtain desired PPs at smaller optimum length. While studying the interaction among such pair of PPs, it is observed that an oscillating pulse train is created in the overlapping zone. The so generated beat frequency can be tuned in a range of 575– 832 GHz when a lengthwise variation of fiber is considered.

A highly nonlinear single mode anomalous dispersion silicon-core fiber is designed and optimized at the operating wavelength of 2.2 µm for the purpose of generating stable temporal pulse doublets. To designate the output pulse pair as a perfect Gaussian doublet, two new parameters, dissimilarity factor ( ρ g ) and co-similarity index (μ cs) are introduced. Different input pulse parameters such as power, pulse width and chirp are optimized to obtain Gaussian temporal doublets at the shortest optimum length (∼few cm) which is sufficiently smaller in comparison to silica fibers reported earlier. The output pulse pairs remain as a doublet for quite a good stability length. In view of serving practical purposes, the possibilities of fluctuations of input power and pulse width are included to investigate the changes in stability length and effective repetition rate (ERR). The change in ERR along the fiber length produces a remarkable change in free carrier concentration in core, which has also been taken into account for the first time as per our knowledge to obtain the temporal pulse doublet in the so designed Si-core fiber.

Meningiomas were named by Harvey Cushing in 1922 and described as common tumors that arise from arachnoid cap cells...

ADNOC Group of Companies are embarking on drilling many of development wells in the upcoming years to achieve the forecasted production mandates. Therefore, the wells completion should be designed to cater for the following reservoir requirements as per as per company expectations: ▪Full accessibility (to TD) for production logging and stimulation.▪Flexibility for conformance control.▪Defined production allocation.▪Fit for purpose completion that can absorb the change in reservoir dynamics throughout well life. The current practice of completing the horizontal wells as open hole "bare-foot" completion and geosteering practice might save some short-term cost, but it may impact the hole accessibility and cost more in the long term. Horizontal well application is one of the key development strategies that will improve the sweeping efficiency and recovery to minimize field development cost by reducing well counts. Longer horizontal require lower completion liners to meet the objectives of the well. Full multi- disciplinary input are needed to properly install an effective lower completion, but robust design often brings strong performance. This paper describes the outcomes of accessibility, geo-steering practices evaluation, fundamental criteria and workflow for selecting the most suitable lower completion design for new and sidetracked wells to achieve ADNOC's production mandates while complying with completion requirements and adhering to reservoir management guidelines. The objective is to optimize the procedures as per ADNOC guidelines in designin, planning and deploying horizontal wells including the Well Post Rig Operation & Monitoring Process, Lessons Learned and assuring full accessibility while meeting integrity and quality of the development wells for future prognosis. The main drivers and objectives for running lower completion are listed below: ▪Enabled to maximize reservoir contact aiming for cost and production optimizations▪Full Accessibility to allow PLTs, Stimulation and re-stimulations.▪Compartmentalized lower completion for remedial actions▪Achieve uniform flow conformance utilizing ICVs & ICDs▪Mitigate and manage water production

The role of specific interactions in the self-assembly process of low molecular weight gelators (LMWGs) was studied by altering the nonbonding interactions responsible for gel formation via structural modification of the gelator/nongelator. This was achieved by modifying pyridyl moieties of bis(pyridyl) urea-based hydrogelator (4–BPU) and the isomer (3–BPU) to pyridyl N–oxide compounds (L1 and L2, respectively). The modification of the functional groups resulted in the tuning of the gelation properties of the parent gelator, which induced/enhanced the gelation properties. The modified compounds displayed better mechanical and thermal stabilities and the introduction of the N–oxide moieties had a prominent effect on the morphologies of the gel network, which was evident from the scanning electron microscopy (SEM) images. The effect of various interactions due to the introduction of N–oxide moieties in the gel network formation was analyzed by comparing the solid-state interactions of the compounds using single crystal X-ray diffraction and computational studies, which were correlated with the enhanced gelation properties. This study shows the importance of specific nonbonding interactions and the spatial arrangement of the functional groups in the supramolecular gel network formation.

Heavy metal has enormous toxicity on microbial metabolic pathways and its corresponding enzymes. Indiscriminate disposal of heavy metals in nature has a huge detrimental impact on the environment and ecosystem. Thus the minimal concentration of heavy metals should be maintained in environment with proper real-time monitoring. In general, ionic chromatography, mass spectrometry, inductively coupled plasma; polarography and usage of ion-sensitive electrodes are the most abundant approaches to detect the heavy metal contamination in nature. However, these current approaches suffer due to lower electrode selectivity, inaccurate response, and higher cost. Moreover, current avenues are not directly consociated with toxicity impact of these heavy metals. In general, algal alkaline phosphatases are a hydrolase (EC 3.1.3.1) class of enzymes, present in external membrane of microalgal regimes. Alkaline phosphatase enzyme transforms phosphoester molecules into soluble inorganic phosphate. However, its catalytic activity has strongly been inhibited in the presence of trace amount of heavy metals. This particular feature of algal phosphatase helps to detect these toxic heavy metals in nature even these are present in minute quantities. Based on this current global scenario, the current study is to focus on in silico screening and identification of algae-based alkaline phosphatases following systems biology approaches. The present study will help to (i) find out novel algae-based putative alkaline phosphatase protein sequences; (ii) bioinformatics and phylogenetic studies toward in silico characterizations, and (iii) algae-based alkaline phosphatase enzyme affinity toward diverse heavy metals especially cadmium and mercury. Therefore, this systems biology approach will accelerate the usage of algae-based alkaline phosphatase as a sustainable biosensor to detect the minute level of heavy metal toxicity in nature in the near future.

This paper attempts to describe the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) or named as novel coronavirus (COVID-19) via an epidemic model. This dangerous virus has dissimilar effects in different countries in the world. It is observable that the number of new active coronavirus cases is increasing day by day across the globe. India is now in the second stage of COVID-19 spreading, and as a densely populated country, it will be an epidemic very quickly if proper protection / strategies are not under-taken based on the database of the transmission of the disease. This paper is using the current data of COVID-19 for the mathematical modeling and its dynamical analysis. As an alternative of the standard SEIR model, we bring in a new representation to appraise and manage the outbreak of infectious disease COVID-19 through SEQIR pandemic model, which is based on the supposition that the infected but undetected by testing individuals are send to quarantine during the incubation period. During the incubation period if any individual be infected by COVID-19, then that confirmed infected individuals are isolated and the necessary treatments are arranged in proper way so that they cannot taint the other residents in the community. Dynamics of the SEQIR model is presented by basic reproduction number R₀ and the comprehensive stability analysis. Numerical results are depicted through apt graphical appearances using the data of five states and India.

Textile based industrial sectors pioneer and govern the present global economy. In practice, current textile industries depend on chemical-based approaches which include following basic techniques likely desizing of fibers, fiber scouring, mercerization of fibers, bleaching with dyeing of fibers, softening of cotton, biopolishing of cotton fibers, denim washing of cotton, and stripping of color. These chemical approaches decline the quality of textile products and fascinate harmful environmental concerns. Even most of these industrial chemicals are corrosive to expensive equipment in textile industries. To this end, this current scenario switches on a paradigm shift from conventional chemical derived avenues to a comparative greener, sustainable, economically viable and environmentally benign alternative catalytic platform in textile industries. Microbial enzymes are the potential key catalytic alternatives of these chemical-based approaches in textile industries. There are two primary groups of microbial enzymes involved in textile industries i.e. hydrolases and oxidoreductases. These key groups of microbial enzymes are most promising considering higher specificities under mild conditions, lower processing time, lower energy and lower water requirements. These preferences improve textile product quality and potential bioprocess integrations. However, existing key industrial microbial enzymes do not show effective efficacies to attain textile industrial requirements (i.e. higher quality textile products) due lower substrate specificities, product inhibition, enzyme stability, lower catalytic efficiencies and lack of efficient naive enzymes time to time. Hence, diverse approaches (i.e. rational enzyme design, metabolic engineering, and systems biology) have been applied to resolve the aforementioned global issues. Therefore, the aim of this current work is to summarize novel and advanced approaches for improving the efficiencies of microbial enzymes with special emphasis on metabolic engineering.

Lignocellulosic biomass utilization is a burning issue at present. Physicochemical composition of lignocellulosic biomass is highly complex. This phenomenon restricts its recycling toward biofuel generations. Diverse treatments have been applied to accelerate the lignocellulosic biomass breakdown. However, not any single approach is effective. Hence, the industry is looking forward to having sustainable microbial platforms that can ameliorate the lignocellulosic biomass accessibility. Therefore, a paradigm shift is expected to develop an efficient microbial cell factory generation that can degrade lignocellulosic biomass devoid of toxic intermediates. Genetic engineering, metabolic engineering, and biology approach could be able to fasten the process to achieve this goal by enhancing enzymatic activity, increasing substrate (cellulose, cellobiose, lignin, pectin, etc.) affinity, and finding novel enzymes; design novel metabolic pathways; and knock-out competing pathway to reduce toxic intermediate accumulations. Hence, the current book chapter summarizes promising genetic and metabolic engineering avenues to enhance lignocellulosic biomass degradation to improve its accessibility for biofuel generations.

A novel methodology was developed that uniquely employs alternating current (AC) electric field to fabricate ice-templated ceramics. In the methodology, AC field was applied to an aqueous ceramic suspension, and then ice-templating was performed. Field application to an aqueous ceramic suspension resulted in a net motion of ceramic particles due to DC voltage generation. Suspension concentration increased near one of the electrodes, which was controllable through AC frequency and field duration. Density of the very bottommost regions in sintered materials increased with field duration, attributed to increased local suspension concentration. In sintered materials, the thickness of non-templated region increased with field duration, whereas templated microstructure turned increasingly dendritic with field duration, suggesting a strong influence of AC field on the growth characteristics of ice crystals. AC-field assisted materials exhibited remarkably enhanced compressive strength without any change in porosity. This work contributes to advancing the ice-templating technology using externally energized fields.

We investigated the effects of platelets and strain rate on the compressive response of ice-templated porous alumina, processed from ultrafine, equiaxed particles and from a mixture of ultrafine, equiaxed and large platelet particles. Results revealed a remarkable enhancement of the quasistatic and dynamic compressive mechanical properties of the templated ceramics in the presence of platelets. Specific compressive mechanical properties of the ice-templated alumina containing platelets are superior in comparison to those of the various metallic, syntactic and natural cellular solids. In the presence of platelets, compressive strength exhibited contrasting strain rate sensitivity between the elastic and inelastic stages of deformation.

We investigated and thoroughly analyzed compressive response of ice-templated ceramics in quasistatic and dynamic regimes of strain rate. In the high pore volume regime, sintered scaffolds exhibited highly lamellar pore morphology and pore architecture transitioned to dendritic with the decreasing pore volume. Mechanical property measurements in the quasistatic regime of strain rate revealed that with increasing density, compressive response transitioned from a damageable, cellular-like failure to a brittle-like failure. We rationalized the measured results in terms of the propensity of the lamella walls to undergo buckling. Our conjecture is that in the high pore volume regime, lamella walls of the scaffolds are prone to buckling-induced elastic instability, which leads to a compressive response that manifests a gradual decrease of stress beyond peak stress. In contrast, we suggest that in the low pore volume regime thick lamella walls and extensive transverse bridging exhibit marked resistance to buckling-induced instability and scaffolds undergo a global failure, which is manifested in the measured quasistatic compressive response as a sharp drop of stress beyond peak stress. Dynamic compressive response of the scaffolds exhibited measurable differences relative to the quasistatic compressive response. Scaffolds exhibited a relatively gradual decrease of dynamic compressive stress beyond peak stress, and an overall improvement of compressive response and energy absorption capacity was measured under the dynamic loading conditions. We rationalized the measured differences in between the strain rate regimes in terms of the micro-inertia and other effects. This study is of critical significance for applications of ice-templated structures in dynamic environments.

Following the internationalisation of food production and manufacturing, a significant increase of food fraud was discovered, ranging from false label claims to the use of additives and fillers to increase profitability. The accidental or fraudulent mixing of animal products or by-products from different species is an important preoccupation for consumers with health or ethical concerns. Gelatin is widely used during food processing as well as in cosmetics, nutraceutics and medical formulations. It contains mainly type I, II and III collagen polypeptides. Gelatin speciation was performed using a well-defined proteogenomic annotation, carefully chosen surrogate tryptic peptides and analysis using a hybrid quadrupole-Orbitrap MS. Gelatin samples were dissolved in ammonium bicarbonate buffer and proteins were digested with trypsin. The samples were analysed using high-resolution MS. Chromatography was achieved using a 30-min linear gradient on a Thermo BioBasic C8 100 × 1 mm column at a flow rate of 75 μL min

Increasing electrode thickness is one route to improve the energy density of lithium-ion battery cells. However, restricted Li+ transport in the electrolyte phase through the porous microstructure of thick electrodes limits the ability to achieve high current densities and rates of charge/discharge with these high energy cells. In this work, processing routes to mitigate transport restrictions were pursued. The electrodes used were comprised of only active material sintered together into a porous pellet. For one of the electrodes, comparisons were done between using ice-templating to provide directional porosity and using sacrificial particles during processing to match the geometric density without pore alignment. The ice-templated electrodes retained much greater discharge capacity at higher rates of cycling, which was attributed to improved transport properties provided by the processing. The electrodes were further characterized using an electrochemical model of the cells evaluated and neutron imaging of a cell containing the ice-templated pellet. The results indicate that significant improvements can be made to electrochemical cell properties via templating the electrode microstructure for situations where the rate limiting step includes ion transport limitations in the cell.

We attempted to develop a phenomenological understanding of the evolution of the fracture events within fine-grained lamella walls of partially deformed ice-templated sintered Al 2 O 3 scaffolds and revealed the effects of the platelets on the crack propagation characteristics. Detailed microstructural analyses suggest that intergranular cracks within the walls evolved at two orientations, parallel and perpendicular to the loading direction. We proposed probable mechanisms including one based on the so-called wing-crack model to rationalize the observed crack orientations. We presented crack propagation behavior in lamella walls in presence of the platelets and discussed the effects in terms of the crack deflection mechanism.

There was a gap in the proof of Theorem 4.1 of [1]. In this corrigendum, we correct the error.

Background: Oxbow lakes are abundant in indigenous fishes, but they are subject to unsustainable fishing practices, potential overexploitation, and indiscriminate use of fine-meshed fishing gear. To quantify the catch per unit effort (CPUE) and impact of fishing gears on fish abundance, a survey was carried out in an oxbow lake in eastern India. Methods: The gear-wise CPUE for fish caught in per unit hour of operation was calculated by dividing the total sampling gear catch in biomass, which is the observed value of fish caught by a particular gear, by the total sampling effort hours. A value of P < 0.05 was accepted as statistical significance. Results: Average annual values of the CPUE of triangular push nets, gill nets, long lines, seine nets, drag nets, stationary dip nets, cone-framed cast nets, and line and hook were calculated as 328.34, 4.12, 36.71, 572.92, 3928.57, 237.78, 235.80, and 0.44 grams of fish per hour of operation, respectively. All the 8 different gears exhibited lower CPUE during monsoon and post-monsoon seasons than in the premonsoon season. The line and hook was dominant (>71%). Cone-framed cast net hauled the maximum catch in biomass (31.51%), and gill nets contributed the maximum number of fish (64.92%). The lower CPUE values of line and hook, gill net, cone-framed cast net and long lines identified them as the most harmful among all gears. Conclusion: Indiscriminate use of gear, particularly line and hook, gill nets, cone-framed cast nets, and long lines, demands regulations and preventions concerning such gear to obtain higher fish abundance.

This paper describes nonlinear dielectric composite passive components on flexible metallic substrates for transient protection of electronic devices, most notably against electrostatic discharge (ESD) and electrical overstress (EOS) conditions. In this case, the passive device comprises a polymer composite that contains nonlinear inorganic fillers, an electric field switchable dielectric ceramic Calcium Copper Titanate (CaCu3Ti4O12, CCT), in a metal insulator metal (MIM) configuration. Compatibility with PCB (printed circuit board) in line processing is demonstrated since the fabrication process described is a relatively low temperature process. Advantageously, the construction of such components are such that they can be embedded within a PCB (printed circuit board), thereby allowing miniaturization of the circuit design and can potentially be adopted in an industrial roll to roll manufacturing process. The dielectric characteristics of the CCT filler polymer composites are compared with well-known high dielectric constant Barium Titanate filler polymer composites for capacitor applications. Theoretical models based on effective medium theory are used to predict the dielectric properties of the CCT epoxy composites as a function of filler loading fractions. Maxwell Garnett model was found to provide the best fit to experimental data.

Ice-templated ceramics have unique lamellar pore morphology that offers better compressive mechanical properties in comparison to the typical ceramic foams with isotropic pore morphology. However, for very high-level porosity (>65 vol%) strength difference diminishes. This investigation reveals that by inducing anisotropic grains within the matrix of a fine-grained ceramic, uniaxial compressive response of the ice-templated sintered scaffolds can be markedly enhanced without causing any considerable modification of the total porosity. To address this innovative materials design strategy, we synthesized a series of microstructures by systematically varying the anisotropic grains content in an aqueous suspension and the freezing kinetics to investigate the process-microstructure correlations and understand the structure-property relationships. Microstructural investigations revealed the unique arrangements of the platelets within and out of the lamella walls, where the upward moving ice fronts aligned the platelets' in-plane direction to the ice-growth direction. In the low freezing front velocity regime, platelets were observed to be mainly within the lamella walls, whereas platelets started to develop lamellar bridges with the increasing velocity. As a result, a transition of the pore morphology occurred with the increasing platelets content and the freezing front velocity. A novel method based on the rigorous microstructural analysis is developed to estimate the distribution of the platelets within and out of the walls and the variation of the platelets distribution with the composition and freezing front velocity. A drastic improvement of the compressive mechanical properties (stiffness, strength, energy absorption capacity) was measured due to the platelets' addition, which has been related to the platelets' distribution within and out of the walls and the pore morphology modifications. Results are rationalized based on the role of the platelets during the compressive deformation.

This paper describes the effects of the grain-level anisotropy on the microstructure and uniaxial compressive response of the ice-templated alumina scaffolds. Highly porous (~ 80 vol.%) scaffolds were fabricated from alumina powders of equiaxed morphology as well as from powder mixtures containing equiaxed and small amount of platelet particles. Presence of the platelets (diameter 8 μm and thickness 400 nm) led to the formation of the interlamellae bridges, and significantly enhanced the stiffness and compressive strength of the scaffolds. Measured improvement of the mechanical response is rationalized based on the stiffening and strengthening effects exhibited by the intralamella and interlamella platelets.

Publisher's version (útgefin grein), The factors affecting the self-assembly process in low molecular weight gelators (LMWGs) were investigated by tuning the gelation properties of a well-known gelator N-(4-pyridyl)isonicotinamide (4PINA). The N—H···N interactions responsible for gel formation in 4PINA were disrupted by altering the functional groups of 4PINA, which was achieved by modifying pyridyl moieties of the gelator to pyridyl N-oxides. We synthesized two mono-N-oxides (INO and PNO) and a di-N-oxide (diNO) and the gelation studies revealed selective gelation of diNO in water, but the two mono-N-oxides formed crystals. The mechanical strength and thermal stabilities of the gelators were evaluated by rheology and transition temperature (Tgel) experiments, respectively, and the analysis of the gel strength indicated that diNO formed weak gels compared to 4PINA. The SEM image of diNO xerogels showed fibrous microcrystalline networks compared to the efficient fibrous morphology in 4PINA. Single-crystal X-ray analysis of diNO gelator revealed that a hydrogen-bonded dimer interacts with adjacent dimers via C—H···O interactions. The non-gelator with similar dimers interacted via C—H···N interaction, which indicates the importance of specific non-bonding interactions in the formation of the gel network. The solvated forms of mono-N-oxides support the fact that these compounds prefer crystalline state rather than gelation due to the increased hydrophilic interactions. The reduced gelation ability (minimum gel concentration (MGC)) and thermal strength of diNO may be attributed to the weak intermolecular C—H···O interaction compared to the strong and unidirectional N—H···N interactions in 4PINA., We thank the University of Iceland Research Fund and the Science Institute for funding. D.G. thanks the University of Iceland for the Doctoral Research and Teaching Assistantship grant. We thankfully acknowledge Jonathan Steed, Durham University, Durham, UK for rheology experiments, Sigurjur Sveinn Jonsson, ISOR-Iceland for X-ray powder diffraction analysis, and Sigridur Jonsdottir, University of Iceland for NMR and mass spectroscopy. We thank Rannís Iceland for granting an infrastructure grant for a single-crystal X-ray diffractometer.

The metabolites of the mammalian kynurenine (KYN) pathway are generated from a branch of tryptophan metabolic pathway. The latter generates 3-hydroxykynurenine (3-HK), kynurenic acid (KYNA), quinolinic acid (QUIN), and picolinic acid (PIC) which are all strongly neuroactive, often with dramatically contrasting functional outcomes. Whereas KYNA and PIC are neuroprotective, 3-HK and QUIN are potently neurotoxic and attributed in major neurodegenerative diseases like schizophrenia, Alzheimer's disease, Huntington's disease, bipolar disorder, and depression. It is increasingly evident that the ratio(s) between the neurotoxic and neuroprotective metabolites may help predict the manifestations of disease vs. health. Therefore high-throughput platforms for determining the relative levels of these kynurenine metabolites in biofluids offer considerable potential. Current analytical tools for studying KYN pathway include assays of branching enzymes, PCR, immunoanalysis, and LCMS. None of these offer high-throughput, cost-effective analyses suited for clinical or drug-screening applications. In this report a laser desorption ionization mass spectrometry (LDI-MS) method is described using SBA-15 mesoporous silica. The system allows fast, high-resolution quantitation of neurotoxic kynurenines using targeted metabolomics on conventional MALDI platforms.

Cyclic adenosine monophosphate (3',5'-cAMP) is a multifunctional second messenger which controls extremely diverse and physiologically important biochemical pathways. Among its myriad roles, 3',5'-cAMP functions as an intracellular regulator of lysosomal pH, which is essential for the activity of acidic lysosomal enzymes. Defects in lysosomal acidification are attributed to many diseases like macular degeneration, Parkinson's, Alzheimer's, and cystic fibrosis. Strategic re-acidification of defective lysosomes by pharmacological increase of intracellular cAMP offers exciting therapeutic potential in these diseases. Modular assays for accurate assessment of intracellular cAMP and lysosomal pH are a critical component of this research. We describe label-free targeted metabolomics for quantitating intracellular cAMP and integrated assays for measuring lysosomal pH. These hybrid assays offer fast, unbiased information on intracellular cAMP concentrations and lysosomal pH that can be applied to many cell types and putative drug screening strategies.

The present work deals with the compensation of third-order dispersion (TOD) in view of parabolic pulse (PP) generation in standard normal dispersion-decreasing fiber (NDDF) links by using phase modulator (PM) at certain position within the link. Since the inherent TOD in the fiber leads to an asymmetric pulse shape and thus degrades the PP formation, there is a strong requirement to minimize the TOD within the fiber link. It is seen that insertion of PM at the estimated critical length reduces misfit parameter satisfactorily at the output end and an equivalent PP is regenerated. A three-stage cascaded system comprising the first section of NDDF, dispersion-shifted fiber (DSF) and a normal dispersion fiber (NDF) may also be useful to mitigate TOD by showing the equivalent performance as that obtained by employing PM in the previous case.

We investigate the asymptotic behaviour of Castelnuovo-Mumford regularity of Ext and Tor, with respect to the homological degree, over complete intersection rings. We derive from a theorem of Gulliksen a linearity result for the regularity of Ext modules in high homological degrees. We show a similar result for Tor, under the additional hypothesis that high enough Tor modules are supported in dimension at most one; we then provide examples showing that the behaviour could be pretty hectic when the latter condition is not satisfied., Comment: 24 pages, updated version

Cyclic adenosine monophosphate (3',5'-cAMP) is a multifunctional second messenger which controls extremely diverse and physiologically important biochemical pathways. Among its myriad roles, 3',5'-cAMP functions as an intracellular regulator of lysosomal pH, which is essential for the activity of acidic lysosomal enzymes. Defects in lysosomal acidification are attributed to many diseases like macular degeneration, Parkinson's, Alzheimer's, and cystic fibrosis. Strategic re-acidification of defective lysosomes by pharmacological increase of intracellular cAMP offers exciting therapeutic potential in these diseases. Modular assays for accurate assessment of intracellular cAMP and lysosomal pH are a critical component of this research. We describe label-free targeted metabolomics for quantitating intracellular cAMP and integrated assays for measuring lysosomal pH. These hybrid assays offer fast, unbiased information on intracellular cAMP concentrations and lysosomal pH that can be applied to many cell types and putative drug screening strategies.

Quantitative relationship of primary productivity and fish productivity and estimating aquatic health indices in tropical oxbow lake ecosystems remains to be addressed as predictors of fisheries yield in sustainable management. The aquatic health indicators and aquatic health status assessed with biological properties of phytoplankton, zooplankton, macroinvertebrates, macrophytes and fish in a semi-closed tropical oxbow lake ecosystem in the eastern India were studied along with socioecological and socio-economical aspects. Five ecological classes namely phytoplankton, zooplankton, macroinvertebrate, macrophyte and fish have been championed as effective biological indicators supported by physicochemical attributes. The established aquatic health indices registered the health status as moderate to poor. Organic loading and consequent nutrient enrichment and water quality deterioration during monsoon led to more homogeneous benthic biotic assemblage. With observed diverse nature of each trophic level of the ecosystem, there occurred a downstream ‘spillover’ of diversity along the food chain. The ‘structure affecting structure’ argument goes in tune with the theory of consumers controlling species diversity. Total 38 fish productivity regression equation models explained clearly that fish abundance and productivity were declining due to high anthropogenic activities of jute retting and indiscriminate uses of fishing gears of various mesh sizes during monsoon and thereafter, which need to be regulated.

We report the crystallisation of three forms of the copper(II) isonicotinate–N-oxide complex and their phase interconversion via solvent-mediated crystal-to-crystal transformation. The different forms of the copper complex have been isolated and characterised by single crystal X-ray diffraction. Gel phase crystallisation performed in hydrogels, low molecular weight gels and gels of a tailored gelator showed crystal habit modification. Crystallisation in aqueous ethanol resulted in the concomitant formation of blue (form-I) and green (form-II/IV) crystals while the use of a low molecular weight gel resulted in the selective crystallization of the blue form-I under identical conditions. Comparison of the gel phase and the solution state crystallisation in various solvent compositions reveals that the blue form-I is the thermodynamically stable form under ambient conditions.

The ice-templating technique enables the fabrication of multilayered ceramic-based composite materials. Very little is known on the inelastic deformation mechanisms that evolve in this class of composite materials under compressive loading conditions and cause macroscopic failure. The current investigation is motivated by a recent study by the authors, which revealed that the uniaxial compressive response of ice-templated ceramic–polymer composites is strongly dependent on the loading direction relative to the layer orientation. The current investigation reveals that the inelastic deformation mechanisms in ice-templated alumina–epoxy composites are strongly influenced by the compressive loading orientation relative to the growth direction of ice crystals. The deformation mechanisms were investigated for the loading directions of 0° (parallel to the growth direction), 45° (to the growth direction), and 90° (to the growth direction). For 0°, kink band formation and longitudinal splitting were observed to be the primary strength limiting mechanisms. Kink band formation could be the primary strength limiting factor and responsible for the catastrophic-type compressive failure response. For the loading directions of 45° and 90°, interface delamination and fracture within the lamella walls and across the alumina–epoxy interfaces were the main deformation mechanisms. These mechanisms significantly reduced the compressive strength but attributed progressive-type failure behavior in ice-templated composites. The knowledge of the inelastic deformation mechanisms in ice-templated ceramic–polymer composites under compressive loading is vital for an improved understanding of structure–mechanical property relationships and hierarchical materials design.

In this paper, we consider a mathematical model to explain, understanding, and to forecast the outbreaks of COVID-19 in India. The model has four components leading to a system of fractional order differential equations incorporating the refuge concept to study the lockdown effect in controlling COVID-19 spread in India. We investigate the model using the concept of Caputo fractional-order derivative. The goal of this model is to estimate the number of total infected, active cases, deaths, as well as recoveries from COVID-19 to control or minimize the above issues in India. The existence, uniqueness, non-negativity, and boundedness of the solutions are established. In addition, the local and global asymptotic stability of the equilibrium points of the fractional-order system and the basic reproduction number are studied for understanding and prediction of the transmission of COVID-19 in India. The next step is to carry out sensitivity analysis to find out which parameter is the most dominant to affect the disease’s endemicity. The results reveal that the parameters η , μ and ρ are the most dominant sensitivity indices towards the basic reproductive number. A numerical illustration is presented via computer simulations using MATLAB to show a realistic point of view.

This work is motivated by the structural gradient observed in natural materials to investigate the influence of the loading direction on the compressive response of ice-templated alumina-epoxy composites. Although this investigation is not on the development of multilayered composites with a structural gradient, the current results can help understand the mechanical behavior and design of such materials. Ice-templated alumina materials were developed from 20 vol% suspensions at high freezing-front velocity (FFV) and from 30 vol% suspensions at high and low FFVs. From porous ceramics, specimens were extracted at different orientations relative to the growth direction of ice crystals and infiltrated with epoxy. The resultant composites varied in ceramic fraction and morphology. For compression along the growth direction of ice crystals, specimens exhibited either high strength with brittle-like (catastrophic) failure or low strength with ductile-like (progressive) failure. Away from growth direction, strength decreased significantly, and failure was ductile-type. The strength exhibited a strong dependence on ceramic fraction and morphology. At each orientation, strength data of both porous ceramics and composites showed significant variability, and Weibull analysis suggested a connection between their strength. Direct visualization revealed the influence of loading orientation and morphology on deformation and failure in composites. Using the Tsai-Hill failure criterion, the role of competitive failure mechanisms on the compressive response of composites was evaluated. From the knowledge of composition, compressive and bend strength of ceramic phase, and yield strength of polymer phase, upper bound and lower bound of strength were predicted, which encompassed the strength of composites.

Ice-templating technique enables the synthesis of novel ceramic materials with directional, anisotropic pores, and the templated structure is highly tunable. Another factor that also drives interest in ice-templated ceramics is that for a comparable level of porosity, the uniaxial compressive strength of these materials can be significantly greater in comparison to that of the conventional open-cell foams. However, the strength advantage is significantly reduced in the materials templated from low solid loading suspensions. Toward this limitation, this study sheds insights into the influence of sucrose (a water-soluble additive) and freezing front velocity (FFV) on microstructure and the uniaxial compressive response of ice-templated sintered lithium titanate (LTO, composition Li4Ti5O12). This study used LTO as a model material. Materials were ice-templated from aqueous suspensions with 20 vol.% LTO powder and sucrose content was varied between 1–4 wt.%. The porosity of the sintered materials was in the range of 60–65 vol.%. Materials processed without sucrose exhibited lamellar morphology and low compressive strength. Sucrose had a marked influence on the connectivity between lamella walls, which significantly increased with sucrose content, and morphology became highly dendritic. The microstructural changes remarkably impacted compressive strength, which increased as high as eight-fold. Moreover, materials processed with sucrose exhibited a significant increase in strength in the continuous brittle crushing regime. By adjusting sucrose content in aqueous suspension and FFV, it is possible to synthesize ice-templated sintered LTO materials with tailored connectivity between lamella walls and harness compressive strength within a wide range of 4–80 MPa.

This study investigates the effects of two different particle sizes (0.3 μ m vs. 0.9 μ m ) on the microstructure and uniaxial compressive response of ice-templated sintered alumina scaffolds as a function of the solids loading of the ceramic suspensions and freezing front velocity (FFV). For a comparable solids loading and FFV, variation of the particle size is observed to have a significant effect on the microstructure of the fabricated scaffolds. Moreover, transition of the pore morphology with the increasing solids loading and FFV is observed to be more drastic for the scaffolds processed from the 0.9 μ m size powder particles compared to the scaffolds processed from the 0.3 μ m size powder particles. Similarly, particle size variation also influenced significantly the relative density and porosity of the scaffolds. Interestingly, in spite of the observed significant differences of the microstructure and relative density, uniaxial compressive stress-strain measurements revealed marginal effects of the particle size variation on the compressive strength. The measured comparable uniaxial compressive response of the sintered alumina scaffolds fabricated from two different particle sizes are rationalized based on the relative density, pore aspect ratio, and interlamellae bridge density.

A number of single and two parameter variational approximations for the LP 01 mode are reported in the literature which has been used to compute the various propagation characteristic parameters, such as, propagation constant, normalised dispersion, splice loss, bending loss etc. for single mode fibers. These studies are limited to optically linear fibers. To our knowledge, these variational approximations have not been used to study the nonlinear optical processes in such fibers. In the present work, using these variational approximations, the generation of self-similar parabolic pulses in graded-index single mode normal dispersive active fibers has been studied. The optimum length L opt of the fiber, after which an input Gaussian pulse turns into a self-similar parabolic pulse, has been computed and the accuracies obtained from these variational approximations have been compared.

The incorporation of graphite as a solid lubricant in the formulation of brake friction material is well-recognized practice. However, achieving the desired level of performances using graphite is still a significant challenge, due to difficulty in dispersion and loading of graphite in composite materials. The present investigation was aimed at identifying the effect of graphite loading on the tribological and thermal properties of a composite made from phenolic resin modified with powdered acrylonitrile butadiene rubber (NBR). Five composites were prepared with different proportions of graphite (0–40 phr) to the phenolic resin. Thermogravimetric analysis (TGA) and thermal conductivity measurements were carried out to demonstrate the thermal stability and thermal conductivity behaviors. Both the thermal stability and thermal conductivity were found to increase with an increase in graphite content. On the other hand, the tribological properties were found to be optimum at a definite loading of grap...