First step of formose or Butlerov reaction involves C–C bond formation between two formaldehyde molecules resulting in glycolaldehyde. This reaction happens under basic conditions in solution. A ...tandem mass spectrometry investigation of dissociation of deprotonated glycolaldehyde in the gas phase, to study the formose reaction in a retro-synthetic point of view, has been reported. In the present work, we have carried out electronic structure theory calculations and quasi-classical direct chemical dynamics simulations to model the gas phase dissociation of the conjugate base of glycolaldehyde. The dynamics simulations were performed on-the-fly using the hybrid density functional B3LYP theory with the 6-31+G∗ basis set under collision induced dissociation (CID) conditions. Trajectories were launched with two different deprotonated forms of glycolaldehyde for a range of collision energies mimicking experiments. Reverse formose reaction was observed primarily from the slightly higher energy isomer via a non-statistical pathway. Intramolecular hydrogen transfer was ubiquitous in the trajectories. Simulation results were compared with experiments and detailed atomic level dissociation mechanisms are presented.
•Glycolaldehyde formation is the first step of formose reaction. .•Classical chemical dynamics simulations investigating the dissociation dynamics of glycolaldehyde anion are reported. .•Simulations were performed under collision induced dissociation (CID) conditions to model a recently reported tandem mass spectrometric study investigating the retro-formose reaction. .•Simulation results are in qualitative agreement with experiments and atomic level mechanisms are presented.
Key message
TFs involved in drought tolerance in plants may be utilized in future for developing drought tolerant cultivars of wheat and some other crops.
Plants have developed a fairly complex ...stress response system to deal with drought and other abiotic stresses. These response systems often make use of transcription factors (TFs); a gene encoding a specific TF together with -its target genes constitute a regulon, and take part in signal transduction to activate/silence genes involved in response to drought. Since, five specific families of TFs (out of >80 known families of TFs) have gained widespread attention on account of their significant role in drought tolerance in plants, TFs and regulons belonging to these five multi-gene families (AP2/EREBP, bZIP, MYB/MYC, NAC and WRKY) have been described and their role in improving drought tolerance discussed in this brief review. These TFs often undergo reversible phosphorylation to perform their function, and are also involved in complex networks. Therefore, some details about reversible phosphorylation of TFs by different protein kinases/phosphatases and the co-regulatory networks, which involve either only TFs or TFs with miRNAs, have also been discussed. Literature on transgenics involving genes encoding TFs and that on QTLs and markers associated with TF genes involved in drought tolerance has also been reviewed. Throughout the review, there is a major emphasis on wheat as an important crop, although examples from the model cereal rice (sometimes maize also), and the model plant Arabidopsis have also been used. This knowledge base may eventually allow the use of TF genes for development of drought tolerant cultivars, particularly in wheat.
Here, we present a portable, selective and cost-effective fiber-optic surface plasmon resonance (SPR) based platform for early detection of Dengue virus. NS1 protein was targeted as the biomarker of ...dengue. Antibody-antigen specific binding was exploited for NS1 antigen detection. The binding of antibody was assisted by a self-assembled monolayer of alkanethiols on the surface of silver-coated unclad fiber. A wavelength interrogation mode of SPR was utilized to detect NS1 antigen in the dynamic range of 0.2–2.0 μg/ml. The 40 nm thick silver coated optical fiber exhibited resonance wavelength around 500 nm and change in resonance wavelength was monitored for each attachment step on the fiber. The sensitivity at the lowest concentration of NS1 antigen was found to be 54.7 nm/(μg/ml). The limit of detection of the sensor was found to be 0.06 μg/ml, which lies in the physiological range of NS1 protein present in the infected blood, hence the present technique may provide a very early detection advantage. Real blood serum samples were also successfully tested on the set-up, confirming compatibility with the conventional methods. The presented field-deployable platform has wide applications in mass monitoring of dengue, such as during outbreaks and epidemics.
•A portable fiber optic-SPR platform demonstrated for early stage Dengue detection.•Antibody-antigen specific binding was utilized for selective detection of NS1 antigen.•A mixed self-assembled monolayer (1-HT + 11-MUA) immobilized to bind anti-NS1 antibody.•The probe was also tested on clinical NS1 positive blood samples.•The sensitivity and limit of detection were determined to be 54.7 nm/(μg/ml) and 0.066 μg/ml respectively.
Thin film composite (TFC) osmotic membranes based on polyacrylonitrile (PAN) and polyamide were prepared for FO applications. The selective properties were optimized by fine tuning preparation ...parameters in the interfacial polymerization process, such as the composition of the reactant monomer mixture, reaction time, and air drying period. The results revealed two key parameters to have a significant influence on the selective layer properties: the surfactant additive and the drying period of the excess amine solution on the support surface before contacting with the second reagent. With the addition of the surfactant (sodium dodecylsulphate, SDS), the salt retention increased from 56.8% to 95.6% without loss in water permeance. The proper removal of the excess amine solution resulted in smoother membrane surfaces with an extra salt retention improvement from 84.2% to 94.5%. In addition, the optimal conditions to prepare an RO-like selective skin deposited on a PAN support were established. The optimal membrane obtained from this work exhibited superior FO performance compared to the commercial HTI membranes.
•Successful preparation of RO-like PAN-supported TFC osmotic membranes.•Relation between formation parameters, membrane morphology and performance.•Identification of IP parameters having a significant impact on TFC membranes.
DNA methylation is a potential epigenetic mechanism that regulates genome stability, development, and stress mitigation in plants. It is mediated by cytosine-5 DNA methyltransferases (C5-MTases). We ...identified 52 wheat C5-MTases; and based on domain structure and phylogenetics, these 52 C5-MTases were classified into four sub-families including MET, CMT, DRM and DNMT2; and were distributed on 18 chromosomes. Cis-acting regulatory elements analysis identified abiotic stress-responsive, phytohormone-responsive, development-related and light-related elements in the promoters of TaC5-MTases. We also examined the transcript abundance of TaC5-MTases in different tissues, developmental stages and under abiotic stresses. Notably, most of the TaC5-MTases (TaCMT2, TaCMT3b, TaCMT3c, TaMET1, TaDRM10, TaDNMT2) showed differential regulation of their transcript abundance during drought and heat stress. Overall, the above results provide significant insights into the expression and the probable functions of TaC5-MTases and will also expedite future research programs to explore the mechanisms of epigenetic regulation in wheat.
•Fifty-two cytosine-5 DNA methyltransferases (C5-MTases) in wheat were identified by genome-wide identification.•C5-MTases were categorized into four sub-families (CMTs, METs, DRMs and DNMT2s) based on their conserved domains.•C5-MTases showed differential regulation of their transcript abundance during drought and heat stress treatments.
Increasing temperature is a key component of global climate change, affecting crop growth and productivity worldwide. Wheat is a major cereal crop grown in various parts of the globe, which is ...affected severely by heat stress. The morphological parameters affected include germination, seedling establishment, source-sink activity, leaf area, shoot and root growth. The physiological parameters such as photosynthesis, respiration, leaf senescence, water and nutrient relation are also affected by heat. At the cellular level, heat stress leads to the generation of reactive oxygen species that disrupt the membrane system of thylakoid, chloroplast and plasma membrane. The deactivation of the photosystem, reduction in photosynthesis and inactivation of rubisco affect the production of photoassimilates and their allocation. This ultimately affects anthesis, grain filling, size, number and maturity of wheat grains, which hamper crop productivity. The interplay of various systems comprising antioxidants and hormones plays a crucial role in imparting heat stress tolerance in wheat. Thus, implementation of various omics technologies could foster in-depth insights on heat stress effects, eventually devising heat stress mitigation strategies by conventional and modern breeding to develop heat-tolerant wheat varieties. This review provides an integrative view of heat stress responses in wheat and also discusses approaches to develop heat-tolerant wheat varieties.
Penicillins represent most commonly prescribed and salient part of antibacterial armamentarium. Due to lack of proper guidance and regulations, especially in developing countries they are ...indiscriminately applied in agricultural sectors (livestock farming, aquaculture and plants). Major concerns related to remaining residues of penicillins in food or environment are allergy, development of antibacterial resistance, environmental pollution, economical losses to food industries, consumers and food safety. Researchers of different disciplines are developing reliable detection methods for penicillins in various samples. Among them biosensors are attracting considerable attention primarily for their instant detection, convenience in application, on-site monitoring and portability. Nowadays, they are becoming more sophisticated with the help of modern approaches such as nanotechnology. This review article summarizes the research literature on advancements and recent trends in the field of biosensors for penicillins quantification till date. Different domains of biosensors (electrochemical, optical, mass-sensitive and thermal) are discussed for penicillins along with their applicability.
Noble metal nanostructures are known to confine photon energies to their dimensions with resonant oscillations of their conduction electrons, leading to the ultrahigh enhancement of electromagnetic ...fields in numerous spectroscopic methods. Of all the possible plasmonic nanomaterials, silver offers the most intriguing properties, such as best field enhancements and tunable resonances in visible-to-near infrared regions. This review highlights the recent developments in silver nanostructured substrates for plasmonic sensing with the main emphasis on surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS) over the past decade. The main focus is on the synthesis of silver nanostructured substrates via physical vapor deposition and chemical synthesis routes and their applications in each sensing regime. A comprehensive review of recent literature on various possible silver nanostructures prepared through these methodologies is discussed and critically reviewed for various planar and optical fiber-based substrates.
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•Facile and green synthesis of Ag-Ag2S nanoheterostructures is demonstrated.•Ag nanorods array on glass substrates was fabricated by glancing angle deposition.•Sewage gas (H2S) ...produced from sewer canal was utilized for sulfurization process.•Potential applications in photocatalytic dye degradation and PEC reaction are shown.•Photocatalytic dye degradation, PEC, SERS and bactericidal effect were also studied.
Multifunctionality and recyclability of Ag nanorods array (well known tas potential SERS substrates) have been explored for other imperative applications like water purification by photocatalytic dye degradation, hydrogen evolution, antibacterial activity, and SERS based detection after sulfurization. An easy and green approach of exposing the Ag nanorods array to sewage H2S gas has been applied for sulfurization. This resulted in multifunctional Ag-Ag2S nanoheterostructures manifesting a metal-semiconductor heterojunction with exceptional optical, electronic and photocatalytic properties. The Ag nanorods array on glass as well as ITO substrates were fabricated by glancing angle deposition technique and then sulfurized by exposing to a sewage site, resulting in Ag-Ag2S nanoheterostructures at ambient conditions and confirmed by several morphological, structural and elemental characterization tools. The fabricated nanoheterostructures are utilized efficiently for important applications including dye degradation under visible light irradiation within 30 min, photoelectrochemical reaction for hydrogen evolution, surface enhanced Raman scattering based detection and significant bactericidal effect. The salient features of synthesized Ag-Ag2S nano-heterostructures comprise an important self-sustainable approach which is pivotal in the present research scenario that requires significant multidimensional applications.
