Electrochemical Activation of Graphite Nanosheets Decorated with Palladium Nanoparticles for High Performance Amperometric Hydrazine Sensor

Herein, we have demonstrated a preparation of palladium nanoparticles on electroactivated graphite nanosheets modified screen printed carbon electrode (PdNPs‐EGNS/SPCE) by a simple electrochemical method. The well‐prepared electrocatalyst was potentially applied to the high performance electrocatalytic oxidation of hydrazine in neutral medium. The PdNPs‐EGNS novel composite was characterized by scanning electron microscope (SEM) and the average diameter and thickness of PdNPs and EGNS were found to be ～38 nm and 85 nm, respectively. The high performance electrocatalytic determination of hydrazine was performed by the amperometric i‐t method. The fabricated sensor displayed irreversible electrocatalytic oxidation of hydrazine with diffusion‐controlled electrode process. The oxidation of hydrazine at PdNPs‐EGNS/SPCE showed wider linear range 0.05–1415 µM and high sensitivity 4.382 µA µM^?1 cm^?2. The as‐prepared electrocatalyst achieved quick response towards hydrazine with a lower detection limit 4 nM.     

Thin films of discotic liquid crystals and their applications

ABSTRACT

Discotic liquid crystals (DLCs) are considered as fascinating systems due to their unique property of self-assembly to yield different columnar structures. DLCs are organic semiconductors and create pathways for the development of numerous optical and electrical devices. The thin films of DLCs can be considered as low dimensional system which can exhibit remarkable optical and physical properties. In this article, we present a review on ultrathin films of some interesting DLC molecules at air–water and air–solid interfaces. The Langmuir monolayer and Langmuir–Blodgett films of DLC molecules are extensively studied. The ultrathin films of DLC molecules can yield highly anisotropic layer wherein the molecular orientation and aggregation can have large impact on the physicochemical properties of the film. Different surface phases with different molecular orientations as function of surface density and temperature can be obtained by forming the Langmuir monolayer of the DLC molecules at the air–water interface. The Langmuir monolayer in a particular phase can be deposited onto the active area of a device layer-by-layer by employing a highly controlled Langmuir–Blodgett technique. Here, we report some interesting results related on molecular orientation of the DLC molecules at different interfaces. Such aggregation of DLC molecules in ultrathin films may find applications in thin film-based electro-optical devices.     

Proteomic Analysis of Plasma Proteins in Diabetic Rats by 2D Electrophoresis and MALDI-TOF-MS

Despite tremendous advances in our understanding of the molecular basis of diabetes mellitus, substantial gaps still remain in our understanding of disease pathogenesis and in the development of effective strategies for early diagnosis and treatment. The proteomic approach has offered many opportunities and challenges in identifying new marker proteins and therapeutic targets, i.e., using 2D-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry. The differential protein expressions were analyzed in alloxan-induced diabetic rats treated with Cynodon dactylon leaf extract. The plant extract was administered for 15 days that resulted in a significant increase in plasma insulin and C-peptide levels. We have also identified four differentially expressed proteins from rat plasma. These four diabetes-associated proteins were broadly classified into three groups as per their function: (1) lipid metabolism-associated protein (Apo A-IV), (2) antioxidant activity-related proteins [preprohaptoglobin and heat shock proteins B8 (HspB8)], and (3) muscle function-related protein (TPM3). Apo A-IV, HspB8, and preprohaptoglobin may play a key role in the recovery of diabetes mellitus and also prevent the diabetes-associated complications such as prevention of oxidative stress due to free radical and free hemoglobin. These results show the value of proteomic approach in identifying the potential markers that may eventually serve as diagnostic markers or therapeutic targets.     

X-ray linear dichroism dependence on ferroelectric polarization

X-ray absorption spectroscopy and photoemission electron microscopy are techniques commonly used to determine the magnetic properties of thin films, crystals, and heterostructures. Recently, these methods have been used in the study of magnetoelectrics and multiferroics. The analysis of such materials has been compromised by the presence of multiple order parameters and the lack of information on how to separate these coupled properties. In this work, we shed light on the manifestation of dichroism from ferroelectric polarization and atomic structure using photoemission electron microscopy and x-ray absorption spectroscopy. Linear dichroism arising from the ferroelectric order in the PbZr0:2Ti0:8O3 thin films was studied as a function of incident x-ray polarization and geometry to unambiguously determine the angular dependence of the ferroelectric contribution to the dichroism. These measurements allow us to examine the contribution of surface charges and ferroelectric polarization as potential mechanisms for linear dichroism. The x-ray linear dichroism from ferroelectric order revealed an angular dependence based on the angle between the ferroelectric polarization direction and the x-ray polarization axis, allowing a formula for linear dichroism in ferroelectric samples to be defined.     

Absorbed dose calculations for macromolecular crystals: improvements to RADDOSE

Radiation damage is an unwelcome and unavoidable aspect of macromolecular crystallography. In order to quantify the extent of X‐ray‐induced changes, knowledge of the dose (absorbed energy per unit mass) is necessary since it is the obvious metric against which to plot variables such as diffraction intensity loss and B factors. Significant improvements to the program RADDOSE for accurately calculating the dose absorbed by macromolecular crystals are presented here. Specifically, the probability of energy loss through the escape of fluorescent photons from de‐excitation of an atom following photoelectric absorption is now included. For lighter elements, both the probability of fluorescence and of its subsequent escape from the crystal are negligible, but for heavier atoms the chance of fluorescence becomes significant (e.g. 30% as opposed to Auger electron decay from a K‐shell excited iron atom), and this has the effect of reducing the absorbed dose. The effects of this phenomenon on dose calculations are presented for examples of crystals of an iron‐containing protein, 2‐selenomethionine proteins, a uranium derivatised protein, and for a nucleic acid sample. For instance, the inclusion of fluorescent escape results in up to a 27% decrease in the calculated absorbed dose for a typical selenomethionine protein crystal irradiated at the selenium K‐edge.     

Chemoselective covalent coupling of oligonucleotide probes to self-assembled monolayers

A chemoselective route to routinely and rapidly attach oligonucleotide probes to well-defined surfaces is presented. Cu(I) tris(benzyltriazolylmethyl)amine-catalyzed coupling of terminal acetylenes to azides on a self-assembled monolayer is used instead of traditional nucleophilic-electrophilic coupling reactions. The reaction proceeds well even in the presence of purposely introduced nucleophilic and electrophilic impurities. The density of oligonucleotide probes can be controlled by controlling the amount of azide functionality. Although most of our work was done on gold surfaces, this technique should be readily applicable to any surface on which an azide-containing monolayer can be assembled as we have preliminarily demonstrated by derivatizing azidotrimethoxysilane-modified glass slides with fluorescein-containing oligonucleotides.     

Lasing action of active-particles dispersed in microdroplets and its enhanced characteristics by highly scattering intralipid-10% mixture

The first laser action of active-particles of 1–2 m in diameter, red fluorescent-powder (FP), dispersed in nonactive (nonlasing) 100 m-sized liquid microdroplets is reported. Lasing characteristics of FP-containing microdroplets by mixing Intralipid-10% as highly scattering turbid media are also described. Well-defined lasing thresholds can be confirmed from the FP-dispersed pure microdroplets, and lowered lasing threshold along with enhanced lasing emission is achieved by appropriately mixing the Intralipid-10% solution. Lasing threshold in these microdroplets can be determined not through the spectral narrowing features but through the input–output data. We believe that these new microdroplet configurations offer one of the new categories of lasing media and they seem also to simulate to some biological pigments or organelles contained in cells and small tissues.