Recent Advances in Nanomaterial‐Modified Pencil Graphite Electrodes for Electroanalysis

Pencil graphite electrodes (PGEs) have several advantages over other carbon‐based or commercial metal electrodes, including widespread availability, very low cost, and ease of modification. To make the best use of PGEs in electroanalysis, significant recent advances in the development of different nanomaterial‐PGEs have been observed. The literature published up to mid‐2015 is summarized in the present review, with a focus on the various methodologies used to readily modify graphite pencil electrodes using nanomaterials. This review also touches on the surface characterization of these electrodes and their potential applications in a variety of electrochemical detection applications. The review outlines the scope for further research in this area and discusses the importance of surface modifications of conventional PGE electrodes using nanomaterials or a combination of nanomaterials and electroactive polymers.     

First Synthesis of Continuous Mesoporous Copper Films with Uniformly Sized Pores by Electrochemical Soft Templating

Although mesoporous metals have been synthesized by electrochemical methods, the possible compositions have been limited to noble metals (e.g., palladium, platinum, gold) and their alloys. Herein we describe the first fabrication of continuously mesoporous Cu films using polymeric micelles as soft templates to control the growth of Cu under sophisticated electrochemical conditions. Uniformly sized mesopores are evenly distributed over the entire film, and the pore walls are composed of highly crystalized Cu.     

Typical conversion of lignocellulosic biomass into reducing sugars using dilute acid hydrolysis and alkaline pretreatment

The development and production of fossil fuel alternatives have become one of the main focal points in recent investigations. Lignocellulosic biomass is a renewable source of fermentable sugars for second-generation biofuels and chemicals via biotechnological pathways. However, the presence of lignin and hemicellulose in lignocellulosic biomass makes it difficult for the biomass to be hydrolyzed or digested during fermentation. Thus, effective biomass pretreatment is vital. The present review shows that chemical pretreatment is the current preferred method to obtain high sugar yields at low cost, with dilute acid and alkaline hydrolysis as the two most reported technologies. Dilute acid favours hydrolysis of the hemicelluloses whereas alkaline hydrolysis targets the lignin fraction. Both methods have merits and demerits, and have been combined with other treatments such as hydrothermal and enzymatic hydrolysis. Further investigation is required to improve the pretreatment processes and to ensure the economic viability of bioconversion.     

A new linoleiyl arabinopyranoside from the bark of Bauhinia racemosa Lam and a new flavonoidal glycoside from the leaves of Cordia dichotoma Linn

Phytochemical investigation is very valuable for the ethnomedicinally important plants Bauhinia racemosa Lam (BR) and Cordia dichotoma Linn (CD) used for the cure of variety of ailments. This study was thus designed for phytochemical investigation of BR bark and CD leaves. Phytoconstituents were isolated from the methanolic extracts of the plants by column chromatography using silica gel as stationary phase. The structures had been established on the basis of their physicochemical and spectral data, i.e. IR, ¹H NMR, ¹³C NMR and MS. Elution of the columns with different solvents furnished six compounds (1–6) from the methanolic extract of BR bark and three compounds (7–9) from the methanolic extract of CD leaves which were structurally elucidated. The present phytochemical investigation reported several new compounds useful in increasing the existing knowledge of phytoconstituents from BR bark and CD leaves which is very valuable, as these drugs are used in the Indian traditional systems of medicine.     

Aligned rank tests in measurement error model

Aligned rank tests are introduced in the linear regression model with possible measurement errors. Unknown nuisance parameters are estimated first and then classical rank tests are applied on the residuals. Two situations are discussed: testing about an intercept in the linear regression model considering the slope parameter as nuisance and testing of parallelism of several regression lines, i.e. whether the slope parameters of all lines are equal. Theoretical results are derived and the simulation study is also made to illustrate good performance of introduced tests.     

Proteomic approach for purification of seminal plasma proteins involved in tumor proliferation

Human seminal plasma contains a large array of proteins required for the normal physiology and metabolism of spermatozoa. These are mainly secreted from prostate epithelium, testes, and seminal vesicles. Fortunately, many of these are found to be present at elevated concentration in seminal plasma and act as a biomarker of different carcinomas as their levels are also enhanced in serum and are found to be involved in tumor progression and metastasis apart from fertility. The proteins which were overexpressed in the seminal plasma of prostate carcinoma patients were identified by 2-DE and MALDI-TOF/MS. We have designed a strategy to purify these four proteins prostate specific antigen (PSA), prostatic acid phosphatase (PAP), Zinc alpha2-glycoprotein (ZAG), and progastricsin (PG), together in homogeneity by using simple chromatographic techniques. Acidic and basic fractions of human seminal plasma were separated by ion exchange chromatography and further purified by gel permeation chromatography. Our results form a new and valuable resource for those attempting structure-based drug designing for prostate and other cancers where the amount of proteins is required in plenty and in native form.     

Experimental design optimization of the capillary electrophoresis separation of leucine enkephalin and its immune complex

To optimize the capillary electrophoretic separation conditions for leucine enkephalin (LE) and the immune complex of the LE and anti-LE reaction, an analysis using a three-level, three-factorial Box-Behnken design was performed. Three separation parameters, buffer pH (X(1)), buffer concentration (X(2)), and applied voltage (X(3)), were chosen to observe the effect on separation responses. The responses were theoretical plate number, migration time of the LE peak, and resolution between the peaks. The optimum conditions and process validation were determined using statistical regression analysis and surface plot diagrams. The capillary electrophoresis optimum separation conditions were established to be 75 mM phosphate buffer at pH 7.00 with an applied separation voltage of 15 kV. By using the analysis technique, the prediction of responses was satisfactory and process verification yielded values within the +/-5% range of the predicted efficiency.     

Novel oxygen sensitive complexes for optical oxygen sensing

Novel optical sensing films for oxygen based on highly luminescent iridium (III) and ruthenium (II) complexes have been developed. These demonstrate excellent long-term photostability (several months) when incorporated into polystyrene membranes. The influence of different plasticizers on the specific luminescence quantum yield, the Stern-Volmer constant, the reversibility and the response time were evaluated. Additionally the sensing films can be sterilized by chemical cleaning and gamma-ray irradiation.     

Competing forward and reversed chain reactions in one-dimensional molecular line growth on the Si(100)-(2 x 1)-H surface

To explore the role of competing forward and reversed chain reactions in the growth of a one-dimensional (1D) molecular line on the Si(100)-(2 x 1)-H surface, controlled experiments were performed with various alkene molecules by scanning tunneling microscopy (STM) at various temperatures. It was observed that the end dangling bond (DB) of a styrene line, fabricated by a chain reaction on the Si(100)-(2 x 1)-H surface at 300 K, initiated a reverse chain reaction at 400 K, leading to the complete disappearance of the styrene line with zero-order desorption kinetics (rate constant k = 1.17 x 10-2 s-1 at 400 K). In the case of 2,4-dimethylstyrene, the reversed chain reaction was observed even at 300 K. These results suggest that the appearance of a molecular line in an STM image is determined by the rates of competing forward and reversed chain reactions at a given temperature. As predicted, 1D lines formed by the DB-initiated chain reaction of 1-hexene and 1-heptene on Si(100)-(2 x 1)-H were observed at 180 K because of the reduced desorption rate, despite the fact that those molecules showed no line growth at 300 K. These results indicate that the scope of forming 1D molecular lines on the Si(100)-(2 x 1)-H surface with various alkenes is much wider than anticipated in previous studies.