Silver nanoparticle-modified electrodes for the electrochemical detection of neonicotinoid pesticide: clothianidin.

For the first time, stable silver nanoparticles with a diameter less than 20 nm were prepared using SDS as a reducing and stabilizing agent and characterized, and then used to construct modified electrodes. The developed electrodes are more catalytically active towards the reduction of clothianidin. Clothianidin undergoes reduction at -300 mV vs. Ag/AgCl on the silver nanoparticle-modified electrode, whereas no reduction peak was observed on a bare glassy carbon electrode (GCE). The detection limit was found to be 2.4 nM. The reduction potential and detection limits reported in this work are lower than ever reported in the literature. The analytical validity of clothianidin was tested using tomatoes. Validation of electrochemical results has been achieved by comparing them to HPLC results. There is a good agreement between the results and those obtained by HPLC. The proposed sensor opens up new possibilities for the sensing of clothianidin in environmental samples.

A novel, biocompatible and electrocatalytic stearic acid/nanosilver modified glassy carbon electrode for the sensing of paraoxon pesticide in food samples and commercial formulations.

A simple, biocompatible and an enzyme-free sensing platform was developed for detection of paraoxon. The surface of a glassy carbon electrode was modified with an electrodeposition of stearic acid/nanosilver composite at -0.7 V for 40 s. The paraoxon undergoes electro-reduction at -550 mV on the modified electrode, and the limits of detection (LOD) was calculated as 0.1 nM (S/N = 3) using differential pulse voltammetry which is lower than that of the existing materials reported. The high stability observed with the modified electrode for prolonging period indicated that the sensitivity of the electrode remains active for several runs of the analysis. The developed analytical strategy was implemented for onion and paddy grain samples and good recovery rates were observed. Also, it was applied for analyzing the purity of the commercial paraoxon sample. The reliability of the developed strategy was confirmed by comparing the results of electrochemical approach with that of HPLC technique.

Characterization of cellulose fibers in Thespesia populnea barks: Influence of alkali treatment.

Natural fibers are emerging as best alternatives for synthetic materials in selective applications. These fibers may not have the required properties in its raw form and hence needs some alterations in its characteristics. Likely, this article reports enhancement in surface and structural properties of Thespesia populnea bark fiber treated with NaOH under various concentration and soaking period. Fibers treated with 5% NaOH for 60 min yields noteworthy mechanical strength (678.41 ± 48.91 MPa) owing to its relatively high cellulose fraction (76.42%). Fourier transform infrared spectra endorses the removal of non-cellulosic compounds and X-ray diffraction studies reveals 13.6% growth in the size of cellulose crystals on optimally treated fibers. Weibull distribution model statistically interprets the reliability of acquired tensile test results. Finally, microscopic examinations with scanning electron microscopy and atomic force microscopy explore that fiber surface turns rough after alkali treatment and makes it appropriate for reinforcement in polymer matrices.

Assessment of cellulose in bark fibers of Thespesia populnea: Influence of stem maturity on fiber characterization.

Cellulose is the key constituent of natural fibers and its proportion significantly varies with the growth of the plant. Hence, a study on the influence of plant maturity on fiber properties is essential to recognize optimal fiber source. In this investigation, cellulose fibers were successfully extracted from Thespesia populnea tree barks of approximately 10 mm-80 mm diameter stem and the influence of stem growth on physiochemical, thermal, mechanical and morphological characteristics of the fiber were investigated. The diameter of fiber increased from 150 µm to 200 µm with stem growth meanwhile its water uptake capability decreases by 13.8%. FTIR spectra and thermal analysis confirm the presence of cellulose compound in fiber structure, also the fiber can be stable up to 318 °C. The XRD outcome estimates 44-49% crystallinity index with an average crystallite size of 29.625 Å. Under the tensile load, fiber fails primarily by brittle fracture and its tensile strength ranges from 559 MPa to 329 MPa with an average elongation between 2.9% and 1.7%. Morphology analysis illustrates that fiber surface is becoming rough on maturity and can offer good interfacial strength when reinforced with composites.

Isolation and characterization of cellulose fibers from Thespesia populnea barks: A study on physicochemical and structural properties.

Cellulose, a major proportion of all plant resources are not utilized at its best. Hence, this investigation explores the potential of cellulose fraction in bark fibers of Thespesia populnea for real time use by evaluating its anatomical, physicochemical, mechanical, thermal and morphological properties. Anatomical studies confirm two types of phloem fiber cells based on dimensions of secondary cell wall and lumen. Significant concentration of cellulose (70.12%) helps to attain favorable outcomes in tensile strength (557.82 ±â€¯56.29 MPa). FTIR spectra confirm the presence of cellulosic compound in fiber structure and the size of crystalline cellulose is estimated as 35.76 Šusing XRD results. Thermal profile of TGA and DSC validates that fiber is steady up to 245.4 °C and cellulose degradation befalling between 250 °C and 370 °C accounts for major weight loss in fiber. Images acquired through SEM and AFM depict that the fiber surface is smooth with average roughness of 3.002 nm.

Deletion of murine Arv1 results in a lean phenotype with increased energy expenditure.

BACKGROUND: ACAT-related enzyme 2 required for viability 1 (ARV1) is a putative lipid transporter of the endoplasmic reticulum that is conserved across eukaryotic species. The ARV1 protein contains a conserved N-terminal cytosolic zinc ribbon motif known as the ARV1 homology domain, followed by multiple transmembrane regions anchoring it in the ER. Deletion of ARV1 in yeast results in defective sterol trafficking, aberrant lipid synthesis, ER stress, membrane disorganization and hypersensitivity to fatty acids (FAs). We sought to investigate the role of Arv1 in mammalian lipid metabolism. METHODS: Homologous recombination was used to disrupt the Arv1 gene in mice. Animals were examined for alterations in lipid and lipoprotein levels, body weight, body composition, glucose tolerance and energy expenditure. RESULTS: Global loss of Arv1 significantly decreased total cholesterol and high-density lipoprotein cholesterol levels in the plasma. Arv1 knockout mice exhibited a dramatic lean phenotype, with major reductions in white adipose tissue (WAT) mass and body weight on a chow diet. This loss of WAT is accompanied by improved glucose tolerance, higher adiponectin levels, increased energy expenditure and greater rates of whole-body FA oxidation. CONCLUSIONS: This work identifies Arv1 as an important player in mammalian lipid metabolism and whole-body energy homeostasis.

Characterization of a novel natural cellulosic fiber from Prosopis juliflora bark.

Natural fibers from plants are ideal choice for producing polymer composites. Bark fibers of Prosopis juliflora (PJ), an evergreen plant have not been utilized for making polymer composites yet. Hence, a study was undertaken to evaluate their suitability as a novel reinforcement for composite structures. PJ fiber (PJF) was analyzed extensively to understand its chemical and physical properties. The PJF belonged to gelatinous or mucilaginous type. Its lignin content (17.11%) and density (580 kg/m(3)) were relatively higher and lower, respectively in comparison to bark fibers of other plants. The free chemical groups on it were studied by FTIR and XRD. It had a tensile strength of 558±13.4 MPa with an average strain rate of 1.77±0.04% and microfibril angle of 10.64°±0.45°. Thermal analyses (TG and DTG) showed that it started degrading at a temperature of 217 °C with kinetic activation energy of 76.72 kJ/mol.

Brush cytology vs. endoscopic biopsy for the surveillance of Barrett's esophagus.

BACKGROUND AND STUDY AIMS: Periodic surveillance with systematic biopsies is recommended for patients with Barrett's esophagus. Brush cytology has been proposed as a simple inexpensive component of endoscopic surveillance, which may also detect abnormalities prior to detection of histologic abnormalities. The aim of the current study was to determine whether brush cytology provides any additional value over endoscopic surveillance biopsies in patients with Barrett's esophagus. PATIENTS: This retrospective cohort study included 530 patients with Barrett's esophagus undergoing endoscopic surveillance with paired biopsy and cytology specimens at the Cleveland Clinic between January 1994 and July 2008. The main outcome measures were sensitivity, specificity, and concordance rates of cytology and histology. RESULTS: Sensitivity of cytology for any dysplasia was 49 % and specificity was 95 %. However, sensitivity was 82 % for detection of high grade dysplasia/adenocarcinoma but only 31 % for low grade/indefinite for dysplasia. The concordance rate between cytology and histology was 80 %. Histology had a higher dysplasia detection rate than cytology (24.0 % vs. 15.7 %, respectively; P <0.0001). CONCLUSIONS: Cytology has excellent specificity and good sensitivity for the detection of high grade dysplasia/adenocarcinoma but poor sensitivity for low grade dysplasia. There was substantial concordance between cytology and histology for the detection of dysplasia. However, histology had a higher dysplasia detection rate and therefore the value of routine cytology in the surveillance of Barrett's esophagus is questionable.