Rapid,Label‐free Optical Spectroscopy Platform for Diagnosis of Heparin‐Induced Thrombocytopenia

The use of surface‐enhanced Raman spectroscopy (SERS) to determine spectral markers for the diagnosis of heparin‐induced thrombocytopenia (HIT), a difficult‐to‐diagnose immune‐related complication that often leads to limb ischemia and thromboembolism, is proposed. The ability to produce distinct molecular signatures without the addition of labels enables unbiased inquiry and makes SERS an attractive complementary diagnostic tool. A capillary‐tube‐derived SERS platform offers ultrasensitive, label‐free measurement as well as efficient handling of blood serum samples. This shows excellent reproducibility, long‐term stability and provides an alternative diagnostic rubric for the determination of HIT by leveraging machine‐learning‐based classification of the spectroscopic data. We envision that a portable Raman instrument could be combined with the capillary‐tube‐based SERS analytical tool for diagnosis of HIT in the clinical laboratory, without perturbing the existing diagnostic workflow.     

A comparative study on catalytic performance of modified nanocrystalline and microcrystalline zeolite X for synthesis of cumene by transalkylation of 1,4-diisopropylbenzene with benzene

Cumene is a commercially important product in the petrochemical industries. In isopropylation of benzene, 1,4-diisopropyl benzene (1,4-DIPB) is produced as low value by-product. This low value by-product DIPB is used to maximize the production of commercially important product cumene by transalkylation reaction. Reduction of crystal size in zeolite can increase surface area of the external surface and in this way bring about substantial changes in catalytic activity. Moreover modification with rare-earth metal enhances the acidity of zeolite. In this work, nanocrystalline and microcrystalline zeolite X were modified with cerium to study the combine effect of crystal size and ion modification of zeolite on selectivity of cumene in commercially important transalkylation reaction. Benzene and 1,4-diisopropylbenzene in a molar ratio of 1 to 12.5 were subjected to vapour-phase reaction in the temperature range of 498 to 593 K at atmospheric pressure with space time of 5.27–10.54 kg h/kmol. Nanosized crystalline zeolite gives much higher conversions of 1,4-DIPB than microcrystalline zeolite. Over cerium modified nanosized zeolite CeX_N 81.85% conversion of 1,4-DIPB and 97% cumene selectivity were achieved. It was found that stability and activity of CeX_N for cumene synthesis was much higher than that of CeX_M zeolite. Kinetic constants for the reactions were estimated and the activation energies for various reactions over CeX_M were determined. The activation enegy for transalkylation reaction was found to be 78.54 kJ/mol.     

Electrochemical Sensor for Detection of p-Nitrophenol Based on Nickel Oxide Nanoparticles/α-Cyclodextrin Functionalized Reduced Graphene Oxide

p-Nitrophenol (p−NP) is a high priority toxic pollutant and that has harmful effects on human, animals and plants. Thus, the detection and determination of p−NP present in the environment is an urgent as well as highly important requisite. The present article, therefore focused on the construction of a novel electrochemical sensor based on NiO nanoparticles/α-cyclodextrin functionalized reduced graphene oxide modified glassy carbon electrode (NiO−NPs-α-CD-rGO-GCE) for the selective and sensitive detection of p−NP. UV-vis, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction pattern (SAED) and X-ray diffraction (XRD) analysis confirms the formation of highly pure NiO nanoparticles. Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and cyclic voltammetry (CV) were used to characterize the step-wise electrode modification process. DPV was carried out to quantify p−NP within the concentration range of 1−10 μM and found the detection limit of 0.12 nM on the basis of the signal-to-noise ratio S/N=3. The electrode can able to detect different isomers of nitrophenols. Interferences of other pollutants such as phenol, p-aminophenol, o- and m- nitrophenol, 4-chlorophenol, 2,6-dichlorophenol and ions like K⁺, Cd²⁺, Cl⁻, SO₄²⁻ did not affect the sensing of p−NP. The newly developed sensor exhibited diffusion controlled kinetics and had excellent sensitivity, selectivity and reproducibility for the detection of p−NP. The electrode showed good recoveries in real sample analysis.     

Mixed saturated-unsaturated alkyl-chain assemblies: solid solutions of zinc stearate and zinc oleate

The linear saturated stearic acid and the bent mono-unsaturated oleic acid do not mix and form solid solutions. However, the zinc salts of these acids can. From X-ray diffraction and DSC measurements we show that the layered zinc stearate and zinc oleate salts form a homogeneous solid solution at all composition ratios. The solid solutions exhibit a single melting endotherm, with the melting temperature varying linearly with composition but with the enthalpy change showing a minimum. By monitoring features in the infrared spectra that are characteristic of the global conformation of the hydrocarbon chain, and hence can distinguish between stearate and oleate chains, it is shown that solid solution formation is realized by the introduction of gauche defects in a fraction of the stearate chains that are then no longer linear. This fraction increases with oleate concentration. It has also been possible from the spectroscopic measurements to establish a quantitative relation between molecular conformational order and the thermodynamic enthalpy of melting of the solid solutions.     

Tunable Molecular Logic Gates Designed for Imaging Released Neurotransmitters

Tunable dual‐analyte fluorescent molecular logic gates (ExoSensors) were designed for the purpose of imaging select vesicular primary‐amine neurotransmitters that are released from secretory vesicles upon exocytosis. ExoSensors are based on the coumarin‐3‐aldehyde scaffold and rely on both neurotransmitter binding and the change in environmental pH associated with exocytosis to afford a unique turn‐on fluorescence output. A pH‐functionality was directly integrated into the fluorophore π‐system of the scaffold, thereby allowing for an enhanced fluorescence output upon the release of labeled neurotransmitters. By altering the pH‐sensitive unit with various electron‐donating and ‐withdrawing sulfonamide substituents, we identified a correlation between the pK_a of the pH‐sensitive group and the fluorescence output from the activated fluorophore. In doing so, we achieved a twelvefold fluorescence enhancement upon evaluating the ExoSensors under conditions that mimic exocytosis. ExoSensors are aptly suited to serve as molecular imaging tools that allow for the direct visualization of only the neurotransmitters that are released from secretory vesicles upon exocytosis.     

Long range correlation in earthquake precursory signals

Research on earthquake prediction has drawn serious attention of the geophysicist, geologist and investigators in different fields of science across the globe for many decades. Researchers around the world are actively working on recording pre-earthquake changes in non-seismic parameters through a variety of methods that include anomalous changes in geochemical parameters of the Earth’s crust, geophysical properties of the lithosphere as well as ionosphere etc. Several works also have been done in India to detect earthquake precursor signals using geochemical and geophysical methods. However, very few works have been done so far in India in this field through the application of nonlinear techniques to the recorded geophysical and geochemical precursory signals for earthquakes. The present paper deals with a short review of the early works on geochemical precursors that have been carried out in India as yet. With a view to detect earthquake precursory signals by means of gas-geochemical method we developed a network of seismo-geochemical monitoring observatories in India in hot springs and mud volcano crater. In the last few years we detected several geochemical anomalies and those were observed prior to some major earthquakes that occurred within a radius of 1500?km from the test sites. In the present paper we have applied nonlinear techniques to the long term, real-time and natural data sets of radon-222 and associated gamma originated out of the terrestrial degassing process of the earth. The results reveal a clear signature of the long range correlation present in the geochemical time series. This approach appears to be a potential tool to explore intrinsic information hidden within the earthquake precursory signals.     

Effective utilization of spray pyrolyzed CeO2 as optically passive counter electrode for enhancing optical modulation of WO3

Nanocrystalline cerium oxide (CeO₂) thin films were deposited onto the fluorine doped tin oxide coated glass substrates using methanolic solution of cerium nitrate hexahydrate precursor by a simple spray pyrolysis technique. Thermal analysis of the precursor salt showed the onset of crystallization of CeO₂ at 300 °C. Therefore, cerium dioxide thin films were prepared at different deposition temperatures from 300 to 450 °C. Films were transparent (T ~ 80%), polycrystalline with cubic fluorite crystal structure and having band gap energy (Eg) in the range of 3.04–3.6 eV. The different morphological features of the film obtained at various deposition temperatures had pronounced effect on the ion storage capacity (ISC) and electrochemical stability. The larger film thickness coupled with adequate degree of porosity of CeO₂ films prepared at 400 °C showed higher ion storage capacity of 20.6 mC cm^? 2 in 0.5 M LiClO₄ + PC electrolyte. Such films were also electrochemically more stable than the other studied samples. The Ce⁴⁺/Ce³⁺ intervalancy charge transfer mechanism during the bleaching–lithiation of CeO₂ film was directly evidenced from X-ray photoelectron spectroscopy. The optically passive behavior of the CeO₂ film (prepared at 400 °C) is affirmed by its negligible transmission modulation upon Li⁺ ion insertion/extraction, irrespective of the extent of Li⁺ ion intercalation. The coloration efficiency of spray deposited tungsten oxide (WO₃) thin film is found to enhance from 47 to 53 cm² C^? 1 when CeO₂ is coupled with WO₃ as a counter electrode in electrochromic device. Hence, CeO₂ can be a good candidate for optically passive counter electrode as an ion storage layer.     

Study of variation of soil radon exhalation rate with meteorological parameters in Bakreswar–Tantloi geothermal region of West Bengal and Jharkhand,India

Radon gas is the predominant ionizing radiation on earth. Its occurrence is controlled by the presence of uranium in all types of rocks in the earthcrust, apart from local geological features and atmospheric factors which influence its release into the atmosphere. The present work deals with 24 h observation of the dependence of radon exhalation rate from soil on local meteorological parameters at four locations in Bakreswar–Tantloi geothermal region, located in the highly faulted Chhotanagpur Plateau of eastern India. This study is the primary step towards the determination of soil radon exhalation dynamics in this geothermal area.