Laser flash photolysis and an external magnetic field have been used to study the interaction of two quinone molecules, namely, 9,10-anthraquinone (AQ) and 2-methyl 1,4-naphthoquinone, commonly known as menadione (MQ), with one of the DNA bases, guanine (G) and its nucleoside guanosine hydrate (dG). In organic homogeneous medium, it has been observed that G undergoes a predominant hydrogen (H) abstraction reaction with both the quinones while dG supports photoinduced electron transfer (PET) along with H abstraction. On the other hand, in SDS medium, G supports PET with AQ but not with MQ. However, behavior of dG remains unperturbed toward AQ and MQ with the change in medium. All of these observations have been explained on the basis of stabilization of radical ion pair and difference in size of the quinones, which can affect the distance of approach among the interacting molecules.

In this study, electrically doped bio-molecular p-in field-effect transistor (FET) is designed and its electronic properties are investigated. Density functional theory along with non-equilibrium Green's function based first principle approach is used to design the bio-molecular FET at sub-atomic region. Three Adenine and two Thymine molecules are attached together to form 6.24 nm long and 1.40 nm wide bio p-in FET. This device is attached with two platinum electrodes and wrapped with a metallic cylindrical gate at high vacuum. Intrinsic n and p regions can be made possible within a bio-molecular device at room temperature by electrical doping without explicit dopants, which leads to conduct current by the device both in forward and reverse bias. The various quantum mechanical properties have been calculated using Poisson's equations and self-consistent function for the bio-molecular FET. Among these various quantum mechanical properties, the authors obtain high quantum transmission along with satisfactory current for the proposed device during the room temperature operation. The goal of this study is to highlight the design of a bio-molecular p-in FET with satisfactory large current using ultra low power dissipation.

Fluorescence in poly(ethylene glycol) (PEGs 400-12000) solutions is reported here for the first time. PEG solutions form a vesicular organization with the hydrophilic groups attached at both ends which arrange themselves beyond a particular concentration and offer electron-dense regions at the center of the vesicle. These vesicles provide an inherent site for fluorescence generation in PEG solutions. Fluorescence emission was observed at ~380 nm with an excitation wavelength of 300 nm. PEG of molecular weight 6000 was found to show maximum emission intensity at a particular concentration. The formation of PEG vesicles (~1 nm size) was confirmed by dynamic light scattering (DLS) and confocal laser microscopy. On addition of metal ions the polymeric vesicle breaks up to monomeric PEG, and hence, the fluorescence intensity decreases with a red shift. Fluorescence lifetime measurements indicate the nature of complexation of the metals with PEG. Since PEGs are used as one of the phases in aqueous biphasic systems (ABS) of liquid-liquid extractions, the nature of the fluorescence emission spectrum of the PEG phase after extraction was studied. Metal extraction in the PEG-rich phase of an ABS leads to quenching of fluorescence in PEG.

The photophysical behavior of acridine (Acr) shows facilitated water-assisted protonation equilibrium between its deprotonted (Acr* ∼ 10 ns) and protonated forms (AcrH(+*) ∼ 28 ns) within confined region of ordered water molecules inside AOT/H(2)O/n-heptane reverse micelles (RMs). The time-resolved-area-normalized-emission spectra confirm both Acr* and AcrH(+*), while time-resolved-emission spectra depict time evolution between them. Quenching of AcrH(+*) with N,N-dimethylaniline (DMA) is a purely diffusion-controlled bimolecular quenching with linear Stern-Volmer (S-V) plot, while nonlinearity arises with triethylamine (TEA) that forms ground state complex with AcrH(+) (AcrH(+)··H(2)O··TEA) indicating both static and dynamic quenching. Transient intermediates, DMA(•+) and AcrH(•) infer photoinduced electron transfer from DMA to Acr, while those from AcrH(+)··H(2)O··TEA complex suggest water mediated excited-state proton transfer (ESPT) between AcrH(+) and TEA. The ESPT becomes faster in larger RMs due to enhanced mobility of hydronium ions in AcrH(+)··H(2)O··TEA, which reduces in smaller RMs as water becomes much more constrained owing to stronger complexation by excess confinement.

No abstract

Background: Food allergy is increasing worldwide, and Asian countries are not the exception. Still, ample data are lacking in India. We conducted a cross-sectional study in a metropolis of Eastern India to record the presence of food allergy among the local population. Methods: The prevalence of food allergy was investigated among patients reporting to The Institute of Child Health and Mediland Diagnostics in Kolkata, India. A total of 5,161 patients were subdivided into 3 age groups and surveyed accordingly. The evaluation was conducted via a questionnaire and a skin prick test. Results: Among the 5,161 patients tested, 4,160 showed a positive response to one or more food items. Banana (32%), brinjal (29%), wheat (22%), and egg (23%) were found to be dominant allergens. Sixty-three percent of patients with a family history of allergy showed either a sudden or an insidious mode of onset, whereas the remaining 37% suffered insidious allergic symptoms with no record of a family history of allergy. Skin rashes, cough, and sneezing were the major symptoms observed. Patients in the age group of 15-40 years were the most susceptible. Conclusion: It has been observed that certain specific foods consumed in specific regions cause allergies that are unique to their respective populations. In the present study, the most commonly consumed foods in the studied area, e.g. banana, brinjal, wheat, and egg, had severe effects on the local population. Complementary studies in other countries as well as in other parts of India will allow us to gain further insight into this fact. Some other influencing factors were found to be genetics, cultural habits, and occupation. Avoidance of the allergy-causing food is the best way to deal with food allergy.

Background: Aeroallergen sensitization is increasing worldwide. The optimal management of allergic disease requires the identification of the allergic sensitivities of the patient. Complete data of offending aeroallergens are scant from West Bengal, India. Hence, we employed a retrospective analysis of an atopic population of West Bengal to investigate the rate of sensitivity toward common aeroallergens including pollens, molds and house dust mites. Objectives: The aim of the present study was to evaluate the profile of skin prick test (SPT) reactivity of an atopic population of eastern India. Methods: The prevalence aeroallergen sensitization was investigated by SPT along with a questionnaire survey of patients who visited the Allergy and Asthma Research Center of West Bengal, India, from June 2016 to May 2018. Patients were categorized according to the demographic (age, gender) and clinical aspects. Statistical tests were applied to differentiate between age and gender of the sufferers. Results: 524 out of 605 patients exhibited a positive SPT response toward one or more aeroallergens tested. One-way ANOVA following Tukey’s post hoc test reveals the age group of 15–40 years was more sensitized than that of < 15 years and no male-female discrimination was found using the paired t test. House dust mites, namely Dermatophagoides pteronyssinus and Dermatophagoides farinae, elicited most significant SPT results (80.34 and 84.92%, respectively) followed by Cocos (73.28%) and Azaridacta (57.25%) pollen. The most sensitive mold was Alternaria alternata (26.9%). Allergic rhinitis, bronchial asthma and atopic dermatitis were recorded as the common symptoms. Other influencing factors were family history, nature and season/time of onset and house conditions. Conclusion: Following the increasing trend, house dust mite sensitization still held the dominance like in any other Indian population reported earlier. This study would pave the way to construct a standard and minimal SPT panel for the atopic patients of eastern India.

Unlike the simple phenazine (PZ) molecule, one of its derivatives, dibenzo[a,c]phenazine (DBPZ) forms a charge-transfer complex in the triplet state (3ECT) with different amines, e.g., N,N-dimethylaniline (DMA), 4,4'-bis(dimethylamino)diphenylmethane (DMDPM), and triethylamine (TEA). Formation of the 3ECT and radical ion pairs (RIPs) due to electron transfer is identified by laser flash photolysis. The RIPs are much more abundant in the cases of DMA and DMDPM rather than in TEA. Interestingly, a prominent magnetic field effect (MFE) is observed in both the cases of 3ECT and RIPs in homogeneous acetonitrile-water (MeCN/H2O) mixtures. This rare observation of the 3ECT and MFE in non-viscous medium could be explained by considering the extended planar structure of DBPZ and inter-radical hydrogen bonding, mediated by the intervening water molecules. The magnetic field behavior is consistent with the hyperfine mechanism; however, the low B1/2 value for DBPZ-TEA system is ascribed to fast electron exchange due to the close proximity of the corresponding radical ions.