Structural autonomy of a β-hairpin peptide derived from the pneumococcal choline-binding protein LytA

The cell wall of Streptococcus pneumoniae and several other micro-organisms is decorated with a number of the so-called choline-binding proteins (CBPs) that recognise the choline residues in the bacterial surface by means of highly conserved, concatenated 20-aa sequences termed choline-binding repeats (CBRs), that are composed of a loop and a β-hairpin structure. In this work, we have investigated the ability to fold in aqueous solution of a 14-aa peptide (LytA???????[wt]) and a single derivative of it, LytA???????[ND], corresponding to one of the six β-hairpins of the LytA pneumococcal amidase. Intrinsic fluorescence and circular dichroism spectroscopical measurements showed that both peptides spontaneously acquire a non-random conformation which is also able to bind the natural ligand choline. Furthermore, nuclear magnetic resonance techniques allowed the calculation of the structure of the LytA???????[ND] peptide, which displayed a β-hairpin conformation highly similar to that found within the full-length C-LytA module. These results provide a structural basis for the modular organisation of CBPs and suggest the use of CBRs as new templates for the design of stable β-hairpins.     

Adhesion of Dust Particles to Common Indoor Surfaces in an Air-Conditioned Environment

Adhesion between dust particles and indoor surfaces can lead to negative effects on human health by triggering allergic and asthmatic reactions. In this study, adhesion forces of indoor office dust and activated carbon (AC, as model soot) particles to four common indoor materials (Al, Cu, PVC, and glass) were measured by colloidal probe atomic force microscopy. Chemical analysis of office dust shows it is largely made up of oxygenated hydrophilic organic carbon material. Both metal surfaces experienced weaker dust and AC adhesion than PVC or glass by up to 2–12 times lower primarily due to the presence of attractive electrostatic forces in the latter two (non-conducting) surfaces. Dust and AC adhesion were also highly sensitive to surface roughness, with an inverse relationship between adhesion force and roughness due to the reduction in contact area between the particle and a rougher material surface. Capillary forces play only a minor or negligible role in dust and AC surface adhesion. Adhesion models utilizing a purely van der Waals approach such as the simple Hamaker model and modified Rumpf's model are insufficient to determine the actual particle-surface contact radii and requires the accounting of non-van der Waals forces to adhesion.

Copyright 2014 American Association for Aerosol Research     

Impact of microbial transglutaminase on the staling behaviour of enzyme-supplemented pan breads

The effects of microbial transglutaminase (TGM) when added singly and in combination with amylolytic (-amylase, NMYL) and non-amylolytic (xylanase) enzymes on the textural profile of fresh pan beads and pan breads stored for up to 20 days have been investigated in samples made with low and high extraction rate wheat flours following a sponge-dough process. White and whole-wheat enzyme-supplemented bread samples evidenced a similar sensory firming profile but a different quantitative instrumental staling pattern during storage. Two groups of samples with different staling behaviour can be defined according to the absence (faster staling kinetics) or the presence (slower kinetics) of NMYL in the bread formula, the separation being particularly clear for hardness, cohesiveness and resilience in white bread samples. TGM when added to NMYL-supplemented doughs induced synergistic beneficial effects on fresh bread quality and staling kinetics retardation. The binary combination led to breads with softer and less chewy fresh crumbs, increased initial crumb cohesiveness and resilience, and slower crumb staling kinetics and sensory deterioration during storage, particularly for samples made with white flour.     

Behavior of copper-containing high-entropy alloys in harsh metal-dusting environments

Metal dusting is still an unresolved issue at high temperatures. Currently, two material-related strategies to mitigate metal dusting are described in the literature. On the one hand, highly alloyed materials are used, which contain large amounts of protective oxide-forming elements, such as Cr, Al, and Si. The second mitigation strategy is based on inhibiting the catalytic effect of Fe, Ni, and Co. These elements all strongly catalyze the formation of solid carbon from the gas phase. Combining the catalytic protection of Cu alloying for metal dusting with protection by a classical alumina/chromia barrier is a native feature that high-entropy alloys (HEAs) can offer. In this study, the behavior of different equiatomic HEAs with and without Al and/or Cu are studied when exposed at 620°C in a highly aggressive metal-dusting environment.     

Factors influencing the temporal relationship between alcohol consumption and experiences with aggression among college women.

The authors assessed temporal relationships among alcohol use, aggression, and mood using daily data from 179 college women. Participants called an interactive voice response system over an 8-week period. The odds of experiencing verbal, sexual, and physical aggression (odd ratios = 2.25, 19.44, and 11.84, respectively) were significantly higher on heavy drinking days (M = 7.46 drinks) compared to nondrinking days. Both a history of victimization and greater psychological symptom severity influenced the odds of involvement in verbal aggression. The odds of alcohol consumption were 3 times higher during the 24 hr following verbal aggression compared with days in which verbal aggression did not occur. On the day immediately following involvement in either verbal or physical aggression, positive mood decreased and negative mood increased. During the week (2-7 days) following sexual aggression, women's positive mood was decreased. These findings reinforce the need for interventions aimed at reducing heavy episodic drinking on college campuses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition of bile salt resistance promotes antibiotic susceptibility changes in bifidobacterium

The effect of acquired resistance to bile on the antimicrobial sensitivity of two Bifidobacterium strains (Bifidobacterium animalis IPLA4549 and Bifidobacterium longum NIZO B667) was studied. The MICs of 23 different antibiotics belonging to the most clinically important groups were determined by using the Etest method, which comprises nonporous plastic strips calibrated with a predefined gradient of antibiotic concentrations covering 15 twofold dilutions. The strains were sensitive to most antibiotics assayed, although they tolerated relatively high concentrations of gentamicin, kanamycin, streptomycin, polymyxin B, and ciprofloxacin (from 32 to more than 1,024 microg/ml). One of the bile-adapted strains was more strongly resistant to ceftazidime than was its parent bile-sensitive strain, and the other bile-adapted strain had increased resistance to tetracyclines. Therefore, to test the possibility that the acquisition of stable resistance to bile could be associated with a general increase in resistance to some antibiotics, we analyzed the sensitivities of four additional pairs of parent strains and their bile-adapted derivatives to ceftazidime and three tetracyclines (doxycycline, minocycline, and tetracycline). Three of the bile-resistant derivatives had increased resistance to ceftazidime (more than 256-fold) compared with their parents, and two had enhanced resistance to tetracyclines (at least 12-fold). Thus, the acquisition of bile salts resistance in Bifidobacterium induced modifications of the antibiotic resistance patterns. These results suggest that adaptation of probiotics to bile could also change their potential impact on intestinal microbiota, and this possibility deserves further attention.     

Chemical characterization and antioxidant capacity of berries from Clidemia rubra (Aubl.) Mart. (Melastomataceae)

The flora of Latin America attracts gaining interest as it provides a plethora of still unexplored or under-utilized fruits that can contribute to human well-being due to their nutritional value and their content of bioactive compounds. Clidemia rubra (Aubl.) Mart. is a shrub belonging to the family of the Melastomataceae that grows preferably in a tropical climate. This paper comprises a nutritional characterization of the berries from Clidemia rubra and provides data on the phenolic compounds as well as the antioxidant capacity of the fruit. Findings in macronutrients like protein, carbohydrates, and fat were comparable to that of common berry fruits. Clidemia rubra berries seemed to be a good source for dietary fibers and some minerals (Ca, Mn, and Zn). In contrast, contents of titratable acids and ascorbic acid were low. The polyphenolic profile was determined by using HPLC-MS/MS in comparison to standard compounds. Noteworthy amounts of cyanidin 3-O-rutinoside (39.43 ± 1.66 mg/100 g fresh weight (FW)), delphinidin 3-O-rutinoside (23.74 ± 1.18 mg/100 g FW), cyanidin 3-O-glucoside (11.68 ± 0.56 mg/100 g FW), and delphinidin 3-O-glucoside (6.08 ± 0.35 mg/100 g FW) were found. Non-anthocyanin phenolic constituents were phenolic acids (gallic, protocatechuic, p-hydroxy-benzoic, vanillic, and caffeic acid), flavan-3-ols (epigallocatechin, epigallocatechin gallate, and epicatechin gallate), and 11 different myricetin and quercetin derivatives of which quercetin 3-O-arabinoside (5.26 ± 0.16 mg/100 g FW) and quercetin 3-O-rhamnoside (5.06 ± 0.08 mg/100 g FW) were dominating. Anthocyanins and ascorbic acid were mainly responsible for the antioxidant capacity of Clidemia rubra berries assessed with the total oxidant scavenging capacity (TOSC) assay.     

19号花园 伊尔玛夫人的花园

创造一个未来花园,就是任人们沉浸在时间的流逝中,任人们去幻想、影射、猜测、预计未来的脆弱性和各种可能发生的事情……就是与未来打一次赌。这个花园向我们推荐的旅程是在百里挑一的女主人——伊尔玛夫人的预言的引导下完成的,她会在家中接待您。参观者在色彩缤纷和充满符号的天地中探秘,被激起了无穷的好奇心。他在期待、疑虑、犹豫……     

Review of methane mitigation technologies with application to rapid release of methane from the Arctic

Methane is the most important greenhouse gas after carbon dioxide, with particular influence on near-term climate change. It poses increasing risk in the future from both direct anthropogenic sources and potential rapid release from the Arctic. A range of mitigation (emissions control) technologies have been developed for anthropogenic sources that can be developed for further application, including to Arctic sources. Significant gaps in understanding remain of the mechanisms, magnitude, and likelihood of rapid methane release from the Arctic. Methane may be released by several pathways, including lakes, wetlands, and oceans, and may be either uniform over large areas or concentrated in patches. Across Arctic sources, bubbles originating in the sediment are the most important mechanism for methane to reach the atmosphere. Most known technologies operate on confined gas streams of 0.1% methane or more, and may be applicable to limited Arctic sources where methane is concentrated in pockets. However, some mitigation strategies developed for rice paddies and agricultural soils are promising for Arctic wetlands and thawing permafrost. Other mitigation strategies specific to the Arctic have been proposed but have yet to be studied. Overall, we identify four avenues of research and development that can serve the dual purposes of addressing current methane sources and potential Arctic sources: (1) methane release detection and quantification, (2) mitigation units for small and remote methane streams, (3) mitigation methods for dilute (<1000 ppm) methane streams, and (4) understanding methanotroph and methanogen ecology.     

Application of immersion vacuum cooling to water-cooked beef joints - Quality and safety assessment

Immersion vacuum cooling (IVC) was compared against air blast cooling (AB) and vacuum cooling (VC), to establish its applicability to cool water-cooked beef joints. Process parameters (cooling time and cooling loss) and quality parameters (proximate; physical; sensory and microbial analysis) were compared. Results showed IVC samples have lower cooling losses and improved quality properties compared to VC, while generally comparable to AB samples. IVC cooling times were slower then VC, but faster than AB. Sensory results showed no preference between samples (P > 0.05), even though differences in tenderness and juiciness were detected. Cooling methods had no significant effect on thermoduric spore survival or heat activation in the case of Bacillus atrophaeus and Geobacillus stearothermophilus spores. Results confirmed IVC is capable of combining rapid process times and lower mass losses producing microbiologically safe beef joints of overall high quality in terms of sensory, physical and composition characteristics.