Brønsted Acid‐Catalyzed Nucleophilic Substitution of Alcohols

Simple Brønsted acids such as p‐toluenesulfonic acid monohydrate (PTS) or polymer‐bound p‐toluenesulfonic acid efficiently catalyze the direct nucleophilic substitution of the hydroxy group of allylic and benzylic alcohols with a large variety of carbon‐ and heteroatom‐centered nucleophiles. Reaction conditions are mild, the process is conducted under an atmosphere of air without the need for dried solvents, and water is the only side product of the reaction.     

Highly sensitive alkane odour sensors based on functionalised gold nanoparticles

We deposit dense, ordered, thin films of Au–dodecanethiol core/shell nanoparticles by the Langmuir–Schäfer (LS) printing method, and find that their resistance at ambient temperature responds selectively and sensitively to alkane odours. Response is a rapid resistance increase due to swelling, and is strongest for alkane odours where the alkane chain is similar in length to the dodecane shell. For decane odours, we find a response to concentrations as low as 15 ppm, about 600 times below the lower explosive limit. Response is weaker, but still significant, to aromatic odours (e.g. Toluene, Xylene), while potential interferants such as polar and/or hydrogen-bonding odours (e.g. alcohols, ketones, water vapour) are somewhat rejected. Resistance is weakly dependent on temperature, and recovers rapidly and completely to its original value within the error margin of measurement.     

Ferulic, <Emphasis Type="Italic">p</Emphasis>-coumaric,diferulic and triferulic acids contents of corn tortillas prepared with extruded corn flour and enriched with sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench) bran

Two ways of adding sorghum bran to tortillas were evaluated; adding to the corn flour before extrusion or after extrusion. The addition of sorghum bran increased the ferulic (FA), p-coumaric (p-CA), diferulic (di-FA) and triferulic (tri-FA) acids contents in corn flours and tortillas. Extrusion produced an increment of the free forms, and a part of the ferulic acid was degraded as a consequence of the extrusion conditions. Baking produced a reduction of bound and free forms of the phenolic acids in tortillas, however, high retention percentage of the phenolic acids was observed in flours and tortillas (83–90%). The antioxidant activity of flour and tortillas were correlated to the contents of the phenolic acids, especially with bound di-FA and tri-FA combined (r?=?0.92). Adding the sorghum bran before extrusion, produced flours with increased free phenolic acids content, and increased in vitro antioxidant activity.     

Purification and characterisation of a soluble nucleotide pyrophosphatase/phosphodiesterase from prickly pear (Opuntia ficus indica) fruits

A glycosylated metallo-protein, nucleotide pyrophosphatase/phosphodiesterase, in a soluble form was purified to homogeneity from prickly pear (Opuntia ficus indica) fruits. The native protein had a molecular mass of 105 ± 8 kDa and was formed by two apparently identical subunits each containing 1 Ca²⁺ and 1 Mg²⁺ ion. The Opuntia enzyme exhibited hydrolytic activities toward pyrophosphate/phosphodiester bonds of a broad range of natural substrates, but among these, only NAD(P) and NAD(P)H were hydrolysed very efficiently. Moreover, Opuntia pyrophosphatase/phosphodiesterase hydrolysed the artificial substrate thymidine 5′-monophosphate 4-nitrophenyl ester, whereas it did not show any catalytic activity toward bis-4-nitrophenyl phosphate, which is a substrate of other pyrophosphatase/phosphodiesterase enzymes. We observed an increase of enzyme activity from the green to the red stage of fruits development, suggesting that ONPP activity might be related to the ripening of prickly pears. The protein was shown to be resistant to 75 °C for 30 min. Other biochemical characteristics were investigated and are reported here.     

Relationships between acute toxicities of para nitrophenol (p-NP) and nitrobenzene (NB) to Daphnia magna and Photobacterium phosphoreum: physicochemical properties and metabolites under anaerobic/aerobic sequentials

In this study, the acute toxicities of nitrobenzene (NB) and para nitrophenol (p-NP) were investigated in a high rate sequential anaerobic migrating blanket (AMBR)/aerobic completely stirred tank reactor (CSTR) using Microtox and Daphnia magna tests. After sequential anaerobic and aerobic treatments, the inhibitions in the Microtox bacteria decreased from an initial 78.10-48.20% and 4.00%, respectively, in wastewater containing 40.00 mg/L p-NP. The inhibitions of the influent wastewater containing 60.00 mg/L NB decreased from 72.10% to 45.30% and to 4.00% after anaerobic and aerobic treatment, respectively. The acute toxicity removals were 94% and 93% in the effluent of the whole sequential system, for p-NP and NB, respectively. The acute toxicity in the influent was dependent on the parent NB and p-NP concentrations and ons their physicochemical properties such as hydrophobicity, octanol/water partition coefficient and vapour density for both Microtox bacteria and Daphnia magna while the toxicity in the effluent of the anaerobic reactor was strongly dependent on the metabolites of p-NP (p-amino phenol, phenol, NH(4)-N) and NB (aniline) for Microtox test. This effluent was not toxic to Daphnia magna.     

Dynamically modulating the surface plasmon resonance of doped semiconductor nanocrystals

Localized surface plasmon absorption features arise at high doping levels in semiconductor nanocrystals, appearing in the near-infrared range. Here we show that the surface plasmons of tin-doped indium oxide nanocrystal films can be dynamically and reversibly tuned by postsynthetic electrochemical modulation of the electron concentration. Without ion intercalation and the associated material degradation, we induce a > 1200 nm shift in the plasmon wavelength and a factor of nearly three change in the carrier density.     

Promising Treatment for Multiple Sclerosis: Mitochondrial Transplantation

In recent years, several studies have examined the multifaceted role of mitochondria in Multiple Sclerosis (MS), suggesting that, besides inflammation and demyelination, mitochondrial aberration is a crucial factor in mediating axonal degeneration, the latter being responsible for persistent disabilities in MS patients. Therefore, mitochondria have been recognized as a possible multiple sclerosis therapeutic target. Recently, mitochondrial transplantation has become a new term for the transfer of live mitochondria into damaged cells for the treatment of various diseases, including neurodegenerative diseases. In this hypothesis, we propose mitochondrial transplantation as a new, potentially applicable approach to counteract axonal degeneration in multiple sclerosis.     

Memory deficits and memory surfeits: Differential cognitive consequences of tokenism for tokens and observers.

Investigated whether tokens (persons who are the only member of their social category) might suffer more cognitive deficits than nontokens and whether they do so even when they are treated no differently. 48 undergraduate students (acting either as participants or as observers) were led to believe that they were sharing their views on everyday topics with 3 other Ss (actually videotaped confederates) who were either all of the Ss' own sex or all of the opposite sex. In a later memory test, token Ss remembered fewer of the opinions that they and the 3 other Ss had expressed than did nontokens. Observers, in contrast, remembered more of what token Ss said than what the 3 other Ss said. Results suggest that being distinctive had different effects on the distinctive individuals than on those around them. Theoretical and public policy implications are discussed. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anaerobic/aerobic sequential treatment of a cotton textile mill wastewater

The treatment of a wastewater taken from a cotton textile mill was investigated using an anaerobic/aerobic sequential system during an operational period of 87 days. The process units consisted of an upflow anaerobic sludge blanket (UASB) reactor and a continuous stirred tank reactor (CSTR). Wastewater characterization was performed before feeding the reactor system. Glucose‐COD, and azo dyes were added to the textile wastewater for comparative purposes in the final period of operation. The pH values in the effluent of the UASB reactor were suitable for optimal anaerobic treatment in all runs. The biodegradable part of the COD in wastewater was removed effectively, with the anaerobic stage improving the biodegradability of wastewater entering the aerobic stage. The UASB reactor permitted COD and color removals of 9–51% and 46–55%, respectively, at a hydraulic retention time (HRT) of 30 h. COD removal efficiencies were between 40 and 85% and color removal efficiencies were 39–81% in normal and artificially‐colored wastewaters at a total HRT of 5.75 days in the UASB/CSTR reactor system. Benzidine produced from the cleavage of azo bond in the anaerobic stage was effectively removed in the aerobic stage, and was identified by comparison of its HPLC spectrum with that of an authentic specimen. Copyright © 2004 Society of Chemical Industry     

Comparison of PDE-based nonlinear diffusion approaches for image enhancement and denoising in optical coherence tomography

A comparison between two nonlinear diffusion methods for denoising OCT images is performed. Specifically, we compare and contrast the performance of the traditional nonlinear Perona-Malik filter with a complex diffusion filter that has been recently introduced by Gilboa et al.. The complex diffusion approach based on the generalization of the nonlinear scale space to the complex domain by combining the diffusion and the free Schridinger equation is evaluated on synthetic images and also on representative OCT images at various noise levels. The performance improvement over the traditional nonlinear Perona-Malik filter is quantified in terms of noise suppression, image structural preservation and visual quality. An average signal-to-noise ratio (SNR) improvement of about 2.5 times and an average contrast to noise ratio (CNR) improvement of 49% was obtained while mean structure similarity (MSSIM) was practically not degraded after denoising. The nonlinear complex diffusion filtering can be applied with success to many OCT imaging applications. In summary, the numerical values of the image quality metrics along with the qualitative analysis results indicated the good feature preservation performance of the complex diffusion process, as desired for better diagnosis in medical imaging processing.