Structure-dependent Optical Activity of Single-walled Carbon Nanotube Enantiomers

Single-walled carbon nanotube (SWCNT) samples contain a variety of distinct structural species labeled by (n,m) indices. Nearly all of these are helical structures that can exist as left-handed or right-handed optical isomers. Although SWCNT growth processes give equal (racemic) mixtures of these enantiomers, recently developed separation methods can now provide samples with high optical purity. We report quantitative circular dichroism measurements on both enantiomers of five different semiconducting (n,m) species: (6,4), (7,3), (6,5), (8,3), and (8,4), plus one enantiomer of (7,5). The sorted samples were prepared by nonlinear density gradient ultracentrifugation. Helicities are deduced from the signs of circular dichroism (CD) signals at the E₂₂ transition, with guidance from theoretical modeling. For each species, circular dichroism and absorption spectra are compared at the E₂₂ peak to obtain ellipticities normalized to absorbance. The normalized ellipticities show no apparent correlation with SWCNT roll-up angle but decrease smoothly with increasing diameter. These findings represent the first results on structure-dependent nanotube chiroptical properties.     

Injectable Bone Cement Reinforced with Gold Nanodots Decorated rGO-Hydroxyapatite Nanocomposites,Augment Bone Regeneration

Interest in the development of new generation injectable bone cements having appropriate mechanical properties, biodegradability, and bioactivity has been rekindled with the advent of nanoscience. Injectable bone cements made with calcium sulfate (CS) are of significant interest, owing to its compatibility and optimal self-setting property. Its rapid resorption rate, lack of bioactivity, and poor mechanical strength serve as a deterrent for its wide application. Herein, a significantly improved CS-based injectable bone cement (modified calcium sulfate termed as CS_mod), reinforced with various concentrations (0–15%) of a conductive nanocomposite containing gold nanodots and nanohydroxyapatite decorated reduced graphene oxide (rGO) sheets (AuHp@rGO), and functionalized with vancomycin, is presented. The piezo-responsive cement exhibits favorable injectability and setting times, along with improved mechanical properties. The antimicrobial, osteoinductive, and osteoconductive properties of the CS_mod cement are confirmed using appropriate in vitro studies. There is an upregulation of the paracrine signaling mediated crosstalk between mesenchymal stem cells and human umbilical vein endothelial cells seeded on these cements. The ability of CS_mod to induce endothelial cell recruitment and augment bone regeneration is evidenced in relevant rat models. The results imply that the multipronged activity exhibited by the novel-CS_mod cement would be beneficial for bone repair.     

The Kota of the Nilgiri Hills: a demographic study

We report the existence of a surface configuration in a true spore-forming genus having cell wall constituents of type IV. Micropolyspora angiospora, M. caesia and M. faeni freeze-fractured along the wall surface and only had a surface configuration on their aerial mycelium and aerial spores, with none on the substrate mycelium and substrate spore. The surface configuration of Micropolyspora was distinctly more complicated than that of Nocardia. The aerial spores of M. angiospora were characteristic in that they possessed ridges, two kinds of surface configurations (i.e. rodlets and fibres), and a complex pattern on the surface. Some rodlets of this organism were formed of a two-stranded helix, each strand having a diameter similar to that of a fibre.     

Development of Unconventional Fabric from Banana (Musa Acuminata) Fibre for Industrial Uses

ABSTRACT

Banana fiber is a lingo-cellulosic under-exploited bast fiber, which obtained from the pseudo-stem of banana plant (Musa acuminata). In this study, an attempt has been made to explore the possibility of production of needle-punched nonwoven from fibrous material of biowaste for value addition and diversified uses. Mechanical processing for preparation of all banana, banana-jute (1:1), and banana-polypropylene (1:1) blended needle punched nonwoven has been optimized and processing parameters have been suggested. Softening treatment of banana fibre has been done successfully for better processing. Boiling in water with 1% nonionic detergent has been suggested as pre-processing for softening. Tenacity, elongation-at-break, initial modulus, breaking energy, stress relaxation, creep, compressibility, recovery-from-compression, bending load, electrical insulation, thermal insulation, sound insulation, air permeability, and frictional force have been evaluated and analyzed for all the above-mentioned samples. Based on those properties the probable use has been suggested as insulation (thermal and sound) and filter material.     

Monitoring of black tea fermentation process using electronic nose

Black tea fermentation is essentially an oxidation process. After the plucked tea leaves are treated by series of processes called withering (removal of moisture by air flow), pre-conditioning and CTC (essentially maceration and cutting of leaves), the leaves are subjected to the process of fermentation by exposing them to air by laying the cut tea leaves on floor, trough or moving conveyor under controlled temperature, humidity and air-flow conditions. During this process, the leaves change colour from green to coppery brown and the grassy smell gets transformed to floral smell. It is critical that the leaves be allowed to ferment only up to the desired limit and both under and over fermentation result in deteriorated quality of black tea. Out of the two detectable parameters (colour and smell), smell is very important since a strong, very specific fragrance emanates from the leaves once leaves are optimally fermented. A new electronic nose-based approach for monitoring of tea aroma during fermentation is proposed. Two methods namely the 2-Norm method (2NM) and the Mahalanobis distance method (MDM) were tested and the results were correlated with the results of colorimetric tests and human expert evaluation.     

Cytoprotective effects of anthocyanins and other phenolic fractions of Boysenberry and blackcurrant on dopamine and amyloid β‐induced oxidative stress in transfected COS‐7 cells

There is growing interest both from consumers and researchers in the role that berries play in human health. In the experiments reported here, we assessed the ability of anthocyanins and phenolic fractions of Boysenberry and blackcurrant to ameliorate the deleterious effect of the amyloid β_25–35 (100 µmol L^?1, 24 h) and dopamine (1 mmol L^?1, 4 h) on calcium buffering (recovery) of M1 muscarinic receptor‐transfected COS‐7 cells. Cell viability was also studied. Our results demonstrate that extracts of Boysenberry and blackcurrant showed significant protective effect and restored the calcium buffering ability of cells that had been subjected to oxidative stress induced by dopamine and the amyloid β_25–35. Blackcurrant polyphenolics showed slightly higher protective effect against dopamine, whereas Boysenberry polyphenolics had a higher effect against the amyloid β_25–35. In viability studies, all extracts showed significant protective effects against dopamine and amyloid β_25–35‐induced cytotoxicity. Our results provide further evidence for the protective effects of berries against the neurotoxic effect of dopamine and amyloid β_25–35 in brain cells. Copyright © 2007 Society of Chemical Industry     

米糠油加工最新进展

米糠油中富含不皂化物,如维生素E、γ-谷维素、植物甾醇、植物多酚以及角鲨烯等微量成分。但因米糠油中游离脂肪酸（FFA）和丙酮不溶物含量高,导致其加工困难。近年来,为了获得高质量、低炼耗的米糠油,人们对其加工产生了浓厚的兴趣。综述了米糠油加工工艺,包括膜加工技术。