Transesterification of Jatropha curcas oil to biodiesel using highly porous sulfonated biochar catalyst: Optimization and characterization dataset

The study involves a collection of data from the published article titled "Active sites engineered biomass-carbon as a catalyst for biodiesel production: Process optimization using RSM and life cycle assessment "Energy Conversion Management" journal. Here, the activated biochar was functionalized using 4-diazoniobenzenesulfonate to obtain sulfonic acid functionalized activated biochar. The catalyst was comprehensively characterized using XRD, FTIR, TGA, NH3-TPD, SEM-EDS, TEM, BET, and XPS analysis. Further, the obtained catalyst was applied for the transesterification of Jatropha curcas oil (JCO) to produce biodiesel. An experimental matrix was conducted using the RSM-CCD approach and the resulting data were analyzed using multiple regressions to fit a quadratic equation, where the maximum biodiesel yield achieved was 97.1 ± 0.4%, under specific reaction conditions: a reaction time of 50.3 min, a molar ratio of 22.9:1, a reaction temperature of 96.2 °C, and a catalyst loading of 7.7 wt.%. The obtained product biodiesel was analyzed using NMR and GC-MS analyzed and is reported in the above-mentioned article.

Nitrogen-doped carbon dots: Recent developments in its fluorescent sensor applications

Doped carbon dots have attracted great attention from researchers across disciplines because of their unique characteristics, such as their low toxicity, physiochemical stability, photostability, and outstanding biocompatibility. Nitrogen is one of the most commonly used elements for doping because of its sizeable atomic radius, strong electronegativity, abundance, and availability of electrons. This distinguishes them from other atoms and allows them to perform distinctive roles in various applications. Here, we have reviewed the most current breakthroughs in nitrogen-doped CDs (N-CDs) for fluorescent sensor applications in the last five years. The first section of the article addresses several synthetic and sustainable ways of making N-CDs. Next, we briefly reviewed the fluorescent features of N-CDs and their sensing mechanism. Furthermore, we have thoroughly reviewed their fluorescent sensor applications as sensors for cations, anions, small molecules, enzymes, antibiotics, pathogens, explosives, and pesticides. Finally, we have discussed the N-CDs' potential future as primary research and how that may be used. We hope that this study will contribute to a better understanding of the principles of N-CDs and the sensory applications that they can serve.

Vapour-Phase Selective Hydrogenation of γ-Valerolactone to 2-Methyltetrahydrofuran Biofuel over Silica-Supported Copper Catalysts

2-Methyltetrahydrofuran (MTHF) is a desirable biomass-based platform chemical with excellent potential as an ideal biofuel, green solvent, and raw material for synthesizing downstream chemicals. In this work, a series of copper nanoparticles encapsulated on SiO₂ were prepared by the wet impregnation method and evaluated as efficient non-noble metal catalysts for the vapour-phase hydrogenation of γ-valerolactone (GVL) to MTHF in a fixed-bed reactor under mild reaction conditions. The obtained catalyst properties were determined by XRD, FE-SEM, TEM, UV-DRS, TPR, NH₃-TPD, N₂O decomposition and pore size distribution measurements. Meanwhile, the parameters/variables tuning their catalytic performance (activity, conversion, selectivity and stability) were examined. Various Cu loadings featured on the SiO₂ support are essential for tuning the catalytic activity. Among the catalysts tested, a 5 wt% Cu/SiO₂ catalyst showed a 97.2% MTHF selectivity with 71.9% GVL conversion, and showed a stability for 33 h time-on-stream, achieved at 260 °C and atmospheric pressure conditions. It was found that a huge dispersion of Cu metal in support, hydrogen activation ability, abundant acidic sites and surface area are all beneficial for improved MTHF selectivity.

Book Review: Applications of Ion Exchange Materials in Chemical and Food Industries

Background:

A Book Review on Applications of Ion Exchange Materials in Chemical and Food Industries Edited by Inamuddin, Abdullah M. Asiri, and Tauseef Ahmad Rangreez, Springer, 2019, 264 Pages, Print ISBN 978-3-030-06084-8, ISBN 978-3-030-06085-5, DOI: 10.1007/978-3-030-06085-5 In the last two decades, substantial research was carried on the synthesis, modification, and applications of ion exchange resins in catalysis, water technology, and food and chemical industries. This book provides an up-to-date, complete overview of various applications of ion exchange resins in the chemical and food industry.

Methods:

The chemistry of ion exchange resin materials towards its allied applications, including deionization, dealkalization, dehydration, hydrogenation, esterification, reactive separation, synthesis and separation, and purification of industrial products, were well addressed in this book, along with drawbacks and future scope to improve for better performance in terms of the industrial scale.

Results:

This book consists of nine chapters. Altogether, they discuss the applications of ion exchange resins in solid acid catalysis, reaction separation, removal and recovery of metals in chemical reactions, and preparation of Ag-aggregated ion-exchanged silicates, specifically as it is not possible to discuss each and everything in detail. The chapters are presented effectively by reputed experts around the world. That makes this book an exceptionally significant and authentic source of information. It is valuable for a book to provide updated information, review the work done to date, do proper analysis, compare the pros and cons of comparable existing technologies, and guide the reader to research gaps and places where improvement is required.

Conclusion:

This book is an essential reference guide for students, researchers, engineers, professionals, and industrial research and development specialists in chemistry, chemical and biochemical technology, food chemistry, synthetic chemistry, and industrial chemistry.

Recent advances in biomass-derived platform chemicals to valeric acid synthesis

A perspective overview for levulinic acid and/or γ-valerolactone to valeric acid synthesis via thermocatalytic and electrocatalytic systems has been summarized.

Lignin to Value-added Chemical Synthesis

Background:

There is an increasing demand for innovation in petroleum system replacements. Towards this aim, lignocellulosic biomass is suggested as a possible sustainable source for the manufacturing of fuels and chemical production. This paper aims to investigate different kinds of β-O-4 lignin model compounds for the production of value-added chemicals in the presence of ionic liquids. Especially, cheap β-O-4 lignin model guaiacol glycerol ether (GGE) (Guaifenesin) is introduced to produce valuable chemicals and novel products.

Methods:

The research related to chemical depolymerization of lignocellulosic biomass activity is reviewed and an account of different methods such as thermal and microwave for the last 10 years is presented. So, this work provides an excellent background for academic research and it gives an efficient strategy for the manufacturing of novel value-added chemicals at an industrial scale.

Results:

The review concludes that ionic liquid microwave-assisted synthesis is a power-saving, cost-efficient, fast reaction, and clean way with high selectively and purity for the production of high-value chemicals rather than conventional heating. Guaiacol and catechol are some of these valuable chemicals produced from β-O-4 lignin model compounds with high demands and large industrial scale prospects.

Conclusion:

The β-O-4 lignin model compounds such as guaiacol glycerol ether (GGE) (Guaifenesin) are a good platform for developing food materials, perfumery, biorefinery, and pharmaceutical industry by ionic liquids-assisted lignin depolymerization method.

Effect of MWCNTs on Improvement of Fracture Toughness of Spark Plasma Sintered SiC Nano-Composites

Background:

Silicon carbide (SiC) ceramics are promising engineering material due to its phenomenal properties, such as strong corrosion resistance, high-temperature hardness, wear resistance, high thermal conductivity and high stability in aggressive environment. The key problem of SiC is low fracture toughness due to its brittle nature and to circumvent this, herein high ductile material like MWCNT was used as reinforcement by different proportions.

Methods:

Nanocrystalline powdered Silicon Carbide (SiC) of particle size of 40 nm and x % weight ratio of SiC (x = 95%, 90% and 85%) + y % weight ratio of multiwalled carbon nanotubes (MWCNTs) of particle size of 20 nm (y= 5%, 10% and 15%) composites were ball milled and fabricated using spark plasma sintering process with temperature rate of 100 oC/min and external pressure of 50 MPa. The sintered samples were tested according to ASTM standards to verify the mechanical properties of the samples. Further, lattice strain, crystalline size was determined by XRD and crack bridging mechanism was studied by FESEM.

Results:

It was observed that the uniform distributions of MWCNTs were achieved through ultrasonication and ball milling processes, which play a predominant role in increasing fracture toughness. The fracture toughness of the composite improves drastically from 3.71 MPa m1/2 (100% SiC) to 10.21 MPa m1/2 (85% SiC-15% MWCNT). The theoretical and relative densities of the materials were gradually reduced due to the increase in MWCNTs which is due to the lower density of the reinforcement material and an increase in porosity of the samples.

Conclusion:

The MWCNTs act as a bridging aid in sintered samples, FESEM image signifies some pull-outs and crack branching mechanism of MWCNTs which is the reason for increase in the fracture toughness of SiC.

Study of Cobalt Doped GdAlO3 for Electrochemical Application

Background:

Nano perovskite-type structures as denoted by ABO3 (A= RE) have been popular targets of fundamental investigations since they exhibit a wide variety of physical properties depending upon the chemical composition, defects and small changes in atomic arrangements.

Methods:

GdAlO3: Co2+ (1, 3 &9 mol %) was synthesized using the solution combustion method by using stoichiometric quantities of gadolinium nitrate [Gd (NO3)3], aluminium nitrate (Al (NO3)2, and cobalt nitrate Co(NO3)2.

Results:

The morphology, structure and particle size of the prepared GdAlO3: Co2+ sample were characterized by transmission electron microscope (TEM) image. The Fourier transform infrared (FT-IR) spectral analysis confirmed that the as-prepared powder was in pure state. Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs. Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicated that Co2+ dopant is a successful doping material for the fabrication of supercapacitors.

CONCLUSION:

Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs. Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicated that Co2+ dopant is a successful doping material for the fabrication of supercapacitors. From a future perspective, we believe that GdAlO3: Co2+ composite material could be a promising electrode material for the fabrication of various sensors, supercapacitors and solar cells.

Synthesis of Non-Toxic Fe2(WO4)3 Photocatalyst with Efficient Performance

Background:

Environmental pollution has become a worldwide problem. In this regard, decontamination of wastewater and removal of organic pollutants from environment by photocatalysis has emerged as one of the most promising techniques from the last few decades.

Objective :

In order to degrade the harmful pollutants from wastewater, highly efficient non-toxic Fe2(WO4)3 photocatalyst was synthesized via co precipitation method. The photocatalytic activity of the as-synthesized material was examined by degrading methylene blue (MB) under various conditions.

Methods:

For this purpose, different experimental parameters such as catalyst load, model compound concentration, H2O2 percentage and pH value were adjusted for excellent degradation of MB, and response surface methodology (RSM) along with central composite design (CCD) as adequate model was employed for optimization process.

Results:

The experimental results revealed that 1.2 g/L of catalyst load, 10 g/L for dye concentration, 0.5% of H2O2 and pH 7 were found to be the optimized values for the aforesaid parameters. The optimized values led to 93% degradation of MB under UV light exposure. In addition, toxicological studies were analysed using various bioassays for both, untreated and treated samples and a conspicuous reduction (69.12%) in the toxicity level was observed.

Conclusion:

The study signifies that this method is useful for reclamation of water, making it useful for industry and irrigation.

Combination of ZnO Nanoparticle with Marine Sponge Derived Dipeptide for Enhanced Anticancer Efficacy in Liver Cancer Cells and their Toxicity Evaluation on Embryonic Zebrafish

Background:

Nanomaterials-based cancer therapy plays a significant role in increasing the therapeutic efficiency of anticancer drugs, reducing side effects and targeted delivery of the drug payloads. The present study was aimed to enhance the anticancer effect of a novel dipeptide isolated from marine sponge-associated Bacillus pumilus AMK1 by formulating with Zinc oxide (ZnO) nanoparticles for the effective treatment against HepG2 liver cancer cells.

Methods:

ZnO nanoparticles were synthesized by chemical method and size of the nanoparticle was characterized by Scanning electron microscope, X-Ray diffraction and Fourier-transform infrared spectroscopy. Furthermore, ZnO nanoparticles were conjugated with the isolated dipeptide and evaluated for anticancer activity. In addition, distinct morphological changes were observed by performing apoptotic staining methods such as propidium iodide staining and acridine orange/ ethidium bromide staining. Furthermore, embryotoxic and teratogenic effects of conjugated dipeptide on the development of zebrafish embryo were investigated in this study.

Results:

It was observed that conjugated dipeptide showed enhanced cytotoxicity against HepG2 liver cancer cells without any toxic effect on normal liver cells. ZnO with dipeptide showed significant higher apoptosis of liver cancer cells, with around 19% in early apoptosis and 53% in late apoptosis stage. The obtained results suggest that ZnO nanoparticle conjugated dipeptide initiated cytotoxicity through apoptotic death in HepG2 cells. The embryotoxic studies in zebrafish embryos revealed the LC50 197.0 μg/mL. These findings suggest that conjugated dipeptide affected the development of zebrafish embryos only at relatively higher concentrations.

Conclusion:

The experimental results demonstrate that ZnO nanoparticle conjugated dipeptide has the potential to improve anticancer efficacy against liver cancer cells by inducing apoptosis in cancer cells without any effect on normal liver cells.

A Facile Synthesis of Anatase Ni2+ Doped TiO2 Nanorods with Highly Improved Visible-Light Photocatalytic Performance

Objective:

Herein, we reported a simple and effective approach to synthesis of pure and Ni2+ doped TiO2 nanorods by a photon-induced method (PIM) followed by calcination at 850 ºC in air atmosphere.

Methods:

Basically, the PIM was used to tuning the properties of as-prepared TiO2 photocatalyst. These obtained samples were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS) analysis. XRD results reveals that the both pure TiO2 and Ni doped TiO2 nanorods has anatase phase up to 850°C.

Results:

The HR-TEM analysis indicates that doping Ni is favourable to the formation of rod-like TiO2 sample. Also, the observed photocatalytic results demonstrates that the Ni doped TiO2 can be achieved a complete degradation of methylene blue (MB) within 30 min under direct sunlight irradiation as compared to pure TiO2.

Conclusion:

Therefore, this work revealing the doped Ni has a good potential to modification of TiO2 with an excellent photocatalytic activity for water treatment applications.

Book Review: Layered Materials for Energy Storage and Conversion

Background:

A Book Review on Layered Materials for Energy Storage and Conversion Edited by Dongsheng Geng, Yuan Cheng and Gang Zhang, The Royal Society of Chemistry, 2019, 315 Pages, Print ISBN 978-1-78801-426-7, Print ISSN 2046-0066, DOI: 10.1039/9781788016193- FP001.

:

In the earlier decade, the extensive research hot-spot in two-dimensional (2D) layered materials, especially graphene, metal-organic frameworks (MOFs) and transition metal dichalcogenides (TMDCs) benefited from their exceptional chemical, physical, optical, mechanical and electronic properties. This book provides an up-to-date comprehensive overview of synthesis approaches and functionalization routes of graphene and TMDCs and functional properties of intercalated layered materials and its energy applications.

Methods:

The chemistry of layered two-dimensional materials towards its allied applications in electrocatalysis, lithium-ion batteries, sodium-ion batteries, thermoelectric materials, watersplitting and performance of photovoltaic devices are the core issues of energy storage and conversion and they are well addressed in this book.

Results:

This book consists of nine chapters. Altogether they discuss layered materials, energy storage, substitute energy storage and conversion specifically as it is not possible to discuss each and everything in detail. The chapters are written well by reputed experts around the globe. That makes this book an outstandingly important and reliable source of information. It is valuable for a book to provide updated information, review the work done to date, do proper analysis, compare the pros and cons of comparable existing technologies and guide the readers to the research gaps and places where improvement is required.

Conclusion:

This book is an essential reference guide for students, researchers, engineers and professionals in the advanced materials community and energy-related sectors such as photovoltaics, water-splitting, supercapacitor, and batteries, etc.

Book Review on “Nanotechnology: Food and Environmental Paradigm”

Background::

A Book Review on Nanotechnology: Food and environmental paradigm, is edited by Ram Prasad, Vivek Kumar and Manoj Kumar, Springer Nature Singapore, 2017, 340 Pages, ISBN 978-981-10-4677-3, DOI 10.1007/978-981-10-4678-0.

:

This book aims to study the effects of nanomaterials on the environment and food and emphasizes the advantages gained through the application of nanotechnology in the broader area of food and environment.

Methods:

Food web is the core of ecological balance for a sustainable environment. The presence of undesired nanomaterials in the food chain or web causes unwanted toxicity to the plants and animals of the food chain. In majority cases, the presence of nanomaterials in food web causes toxicity, impairment of organs and/ or heavy loss to one or more population. Thus, it is highly required to limit the release of nanomaterials in the environment. It is also necessary to set the norms for the production, use and discard of nanomaterials.

Results:

This book consists of 16 chapters, which all together address a large dimension on the positive and negative effects of nanomaterials and the application of nanotechnology in various fields of food, agriculture and pharmaceutical industry. It is also important to evaluate the cost before implementing any new technology. It is not necessary that good research which performed well in the laboratory must also do well on the industrial scale. A major barrier which can be encountered is actually the cost, which must be less to be implemented.

Conclusion:

Application of desired nanomaterials is advantageous for many industries and quality life. Nano-fertilizers and nanopesticides enhance crop production. Nanotechnology plays a significant role in the food industry, from production, processing to packaging. Diagnostics is a field where nanotechnology is applied too much. New diagnostic methods using nanosensors, nanochips and nanocatalysts are evolving day by day.

Electrochemical (bio) sensors go green

Electrochemical (bio) sensors are now widely acknowledged as a sensitive detection tool for disease diagnosis as well as the detection of numerous species of pharmaceutical, clinical, industrial, food, and environmental origin. The term 'green' demonstrates the development of electrochemical (bio) sensing platforms utilizing biodegradable and sustainable materials. Development of green sensing platforms is one of the most active areas of research minimizing the use of toxic/hazardous reagents and solvent systems, thereby further reducing the production of chemical wastes in sensor fabrication. The present review includes green electrochemical (bio) sensors which are based on firstly, green sensors comprising natural and non-hazardous materials (e.g., paper/clay/zeolites/biowastes), secondly sensors based on nanomaterials synthesized by green methods and lastly sensors constituting green solvents (e.g., ionic liquids/deep eutectic solvents). Electrochemical performances of such green sensors and their benefits such as biodegradability, non-toxicity, sustainability, low-cost, sensitive surfaces, etc. Have been discussed for quantification of various target analytes. Associated challenges, possible solutions, and opportunities towards fabricating green electrochemical sensors and biosensors have been provided in the conclusion section.

Antibacterial Carbon-Based Nanomaterials

The emergence and global spread of bacterial resistance to currently available antibiotics underscore the urgent need for new alternative antibacterial agents. Recent studies on the application of nanomaterials as antibacterial agents have demonstrated their great potential for management of infectious diseases. Among these antibacterial nanomaterials, carbon-based nanomaterials (CNMs) have attracted much attention due to their unique physicochemical properties and relatively higher biosafety. Here, a comprehensive review of the recent research progress on antibacterial CNMs is provided, starting with a brief description of the different kinds of CNMs with respect to their physicochemical characteristics. Then, a detailed introduction to the various mechanisms underlying antibacterial activity in these materials is given, including physical/mechanical damage, oxidative stress, photothermal/photocatalytic effect, lipid extraction, inhibition of bacterial metabolism, isolation by wrapping, and the synergistic effect when CNMs are used in combination with other antibacterial materials, followed by a summary of the influence of the physicochemical properties of CNMs on their antibacterial activity. Finally, the current challenges and an outlook for the development of more effective and safer antibacterial CNMs are discussed.

Interaction-Dependent Interfacial Charge-Transfer Behavior in Solar Water-Splitting Systems

Dual-band-gap systems are promising for solar water splitting due to their excellent light-harvesting capability and high charge-separation efficiency. However, a fundamental understanding of interfacial charge-transfer behavior in the dual-band-gap configuration is still incomplete. Taking CdS/reduced graphene oxide (CdS/RGO) nanoheterojunctions as a model solar water splitting system, we attempt here to highlight the interaction-dependent interfacial charge-transfer behavior based on both experimental observations and theoretical calculations. Experimental evidence points to charge transfer at the CdS-RGO interface playing a dominant role in the photocatalytic hydrogen production activity. By tuning the degree of reduction of RGO, the interfacial interaction, and, thereby, the charge transfer can be controlled at the CdS-RGO interface. This observation is supported by theoretical analysis, where we find that the interfacial charge transfer is a balance between the effective single-electron- and hole-transfer probability and the surface free electron and hole concentration, both of which are related to the surface potential and tailored by interfacial interaction. This mechanism is applicable to all systems for solar water splitting, providing a useful guidance for the design and study of heterointerfaces for high-efficiency energy conversion.

Efficient Vapor-Phase Selective Hydrogenolysis of Bio-Levulinic Acid to γ-Valerolactone Using Cu Supported on Hydrotalcite Catalysts

In this work, Cu nanoparticles (Cu NPs, 2-20 nm) supported on Hydrotalcite catalysts exhibit enhanced selectivity for γ-valerolactone (GVL) during hydrogenolysis of levulinic acid (LA). At 260 °C, over 3 wt% Cu achieved 87.5% of LA conversion with a maximum GVL selectivity (95%). In contrast, LA hydrogenolysis over 3Cu/Hydrotalcite catalyst is highly active and stable toward the production of GVL due to balanced acido-basicity and higher Cu dispersion with ultrasmall particle sizes, which are investigated through the temperature programmed desorption (TPD) of ammonia, N2O titration, and transmission electron microscopy (TEM) analysis. Hydrotalcite in combination with inexpensive Cu catalyst is found to be an efficient and environmentally benign for LA hydrogenolysis.

Vertically Aligned Porous Organic Semiconductor Nanorod Array Photoanodes for Efficient Charge Utilization

Because of inefficient charge utilization caused by localized π-electron conjugation and large exciton binding energy, the photoelectrochemical water-splitting efficiency of organic polymers is seriously limited. Taking the graphitic carbon nitride (g-CN) polymer as an example, we report a novel photoanode based on a vertically aligned g-CN porous nanorod (PNR) array prepared in situ, using a thermal polycondensation approach, with anodic aluminum oxide as the template. The g-CN PNR array exhibits an excellent photocurrent density of 120.5 μA cm^-2 at 1.23 V_RHE under one sun illumination, the highest reported incident photon-to-current efficiency of ∼15% at 360 nm, and an outstanding oxygen evolution reaction stability in 0.1 M Na₂SO₄ aqueous solution, which constitutes a benchmark performance among the reported g-CN-based polymer photoanodes without any sacrificial reagents. When compared with its planar counterpart, the enhanced performance of the PNR array results principally from its unique structure that enables a high degree of aromatic ring π-electron conjugation for higher mobility of charge carriers, provides a direct pathway for the electron transport to the substrate, produces a large portion of hole-accepting defect sites and space charge region to promote exciton dissociation, and also withstands more strain at the interface to ensure intimate contact with the substrate. This work opens a new avenue to develop nanostructured organic semiconductors for large-scale application of solar energy conversion devices.

Facile Integration between Si and Catalyst for High-Performance Photoanodes by a Multifunctional Bridging Layer

Designing high-quality interfaces is crucial for high-performance photoelectrochemical (PEC) water-splitting devices. Here, we demonstrate a facile integration between polycrystalline n⁺p-Si and NiFe-layered double hydroxide (LDH) nanosheet array by a partially activated Ni (Ni/NiO_x) bridging layer for the excellent PEC water oxidation. In this model system, the thermally deposited Ni interlayer protects Si against corrosion and makes good contact with Si, and NiO_x has a high capacity of hole accumulation and strong bonding with the electrodeposited NiFe-LDH due to the similarity in material composition and structure, facilitating transfer of accumulated holes to the catalyst. In addition, the back illumination configuration makes NiFe-LDH sufficiently thick for more catalytically active sites without compromising Si light absorption. This earth-abundant multicomponent photoanode affords the PEC performance with an onset potential of ∼0.78 V versus reversible hydrogen electrode (RHE), a photocurrent density of ∼37 mA cm^-2 at 1.23 V versus RHE, and retains good stability in 1.0 M KOH, the highest water oxidation activity so far reported for the crystalline Si-based photoanodes. This bridging layer strategy is efficient and simple to smooth charge transfer and make robust contact at the semiconductor/electrocatalyst interface in the solar water-splitting systems.

Sacrificial Interlayer for Promoting Charge Transport in Hematite Photoanode

The semiconductor/electrolyte interface plays a crucial role in photoelectrochemical (PEC) water-splitting devices as it determines both thermodynamic and kinetic properties of the photoelectrode. Interfacial engineering is central for the device performance improvement. Taking the cheap and stable hematite (α-Fe₂O₃) wormlike nanostructure photoanode as a model system, we design a facile sacrificial interlayer approach to suppress the crystal overgrowth and realize Ti doping into the crystal lattice of α-Fe₂O₃ in one annealing step as well as to avoid the consequent anodic shift of the photocurrent onset potential, ultimately achieving five times increase in its water oxidation photocurrent compared to the bare hematite by promoting the transport of charge carriers, including both separation of photogenerated charge carriers within the bulk semiconductor and transfer of holes across the semiconductor-electrolyte interface. Our research indicates that understanding the semiconductor/electrolyte interfacial engineering mechanism is pivotal for reconciling various strategies in a beneficial way, and this simple and cost-effective method can be generalized into other systems aiming for efficient and scalable solar energy conversion.

Prevalence & risk factors of pre-hypertension & hypertension in an affluent north Indian population

BACKGROUND & OBJECTIVES

Urban Indians have a high prevalence of insulin resistance, hypertension and cardiovascular disease. We studied the prevalence of pre-hypertension and hypertension, as well their association with cardiovascular risk factors, in a north Indian upper socio-economic population.

METHODS

A total of 1746 adults (age >or=30 yr) residing in an urban colony of high-income group residents in the city of Lucknow, north India, were invited to be enrolled for the study. The response rate was 64 per cent (n=1112). Blood pressure, anthropometry, plasma glucose in response to oral glucose tolerance test and lipids were measured. The variables contributing significantly to pre-hypertension and hypertension were analyzed by multiple logistic regression analysis.

RESULTS

The age and sex adjusted prevalence of hypertension was 32.2 per cent and pre-hypertension was 32.3 per cent. In contrast to hypertension, which was highest in the age group 60-69 yr (64%), prehypertension was highest (36%) in the group 30-39 yr. There was a high prevalence of cardiovascular risk factors in the general population [central obesity (86.7%), elevated LDL cholesterol (22.8%), abnormal glucose tolerance (41.6%) and smoking (20.3% of males)]. Two or more of the cardiovascular risk factors were present in a higher proportion of hypertensive [66%, odds ratio (OR) 3.0, P<0.0001] and pre-hypertensive, (56%, OR 2.0, P<0.0001) compared to normotensive subjects (39%). Subjects with pre-hypertension had body mass index, waist-hip ratio and frequency of glucose intolerance, which was intermediate between normotensive and hypertensive subjects. In multiple logistic regression analysis, increasing age, body mass index, waist hip ratio and impaired glucose tolerance/diabetes were independent risk factors for both hypertension and pre-hypertension.

INTERPRETATION & CONCLUSION

A high prevalence of pre-hypertension and hypertension were noted in affluent urban north Indians. Increasing age, body mass index, central obesity and impaired glucose tolerance/diabetes were significantly associated with both hypertension and pre-hypertension. Pre-hypertension was associated with an increased prevalence of cardiovascular risk factors.

High prevalence of type 2 diabetes mellitus in affluent urban Indians

The highest prevalence of type 2 diabetes mellitus in developing countries occurs in the upper socio-economic group, but this has not been well documented in Indians. The age and sex standardized prevalence of diabetes in 1112 affluent adult Indian subjects was 21.1%. This is the highest prevalence of diabetes reported from India.

Validation and reproducibility of a food frequency questionnaire to assess energy and fat intake in affluent north Indians

BACKGROUND

India is currently witnessing a sharp rise in noncommunicable disorders such as obesity, diabetes, hypertension and cardiovascular diseases. This rise can be related in part to dietary changes such as increased intake of calories, fat (especially saturated fat) and cholesterol. A simple, accurate and reproducible method to measure these nutrients is essential to study the role of diet in these diseases in epidemiological studies. We aimed to develop and validate a food frequency questionnaire that could be used for this purpose.

METHODS

Thirty urban north Indian subjects (age 23-64 years, 16 men) belonging to a high socioeconomic group were studied. The subjects were selected consecutively over a period of 3 weeks from among those participating in an epidemiological survey on cardiovascular risk factors in an affluent population. A 102-item food frequency questionnaire was developed to capture the intake of calories, fat, saturated fat and cholesterol. The results obtained by the food frequency questionnaire were compared with a 5-day diet record. To assess the reproducibility of the food frequency questionnaire, it was re-administered after 3 months to the 23 subjects available.

RESULTS

It took the dietician 20 minutes or less to administer the questionnaire. There was good correlation between the nutrient values as calculated by the food frequency questionnaire and 5-day diet record. The correlation for energy intake was 0.80, and varied between 0.55 and 0.69 for unadjusted intake of other nutrients. After adjusting for calories, the correlation varied between 0.45 and 0.68. In general, the food frequency questionnaire overestimated the energy-adjusted nutrient intake by 6%-17%. When intake was classified into quartiles, there was good agreement between the two methods: 43%-100% for calories; 29%-86% for other nutrients for unadjusted intake; 29%-71% for nutrients after energy adjustment. On calculation of intake after re-administration of the food frequency questionnaire, there was a moderate to strong correlation (energy adjusted r=0.49-0.90) between the two evaluations for various nutrients.

CONCLUSION

The food frequency questionnaire developed for the assessment of nutrient intake in a north Indian population was easy to administer, showed moderate to good correlation with the 5-day diet record and was reproducible.