bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure function analysis of chemical tracer trails in the mesosphere‐lower thermosphere region
Authors: Roberts B. C. , Larsen M. F. 
Published: May 2014

AbstractTrimethyl aluminum (TMA) trails released from sounding rockets have been used extensively as a tracer of the neutral atmospheric motions in the mesosphere/lower thermosphere region and serve as a tracer of the atmospheric structure in the altitude range where the trails are released. In addition to the bulk motion corresponding to the winds, smaller‐scale structure is also evident in the trail images, which can be an indication of turbulence or small‐scale wave behavior. In the 90 to 100 km altitude range, the trails are often visible for periods of 20 to 30 min or even longer, so that the horizontal scale sizes spanned by the trails increase significantly as the trails expand due to the combined effects of turbulent diffusion and horizontal displacements due to vertical shears in the winds. We describe a study involving data from high‐, middle‐, and low‐latitude TMA releases. In each case the structure function for the fluctuation structure within the trails was calculated for a sequence of trail images. Each image in the sequence corresponds to an outer horizontal spatial scale that increases with time. By analyzing the time evolution of the structure function, changes in the dynamical processes associated with the form of the structure function have been identified as a function of time and thus also of the increasing horizontal spatial scale size. A consistent pattern is found for all locations, namely a transition in fitted exponent for the structure function that suggests a change from more isotropic turbulence immediately after the trail is released to stratified turbulence at the later times when the horizontal scale size has increased to several hundred kilometers. The transition is found to occur near a horizontal spatial scale in the range between 100 and 200 km.
Individual and coupled influences of AMO and ENSO on regional precipitation characteristics and extremes
Authors: Goly Aneesh , Teegavarapu Ramesh S. V. 
Published: May 2014

AbstractUnderstanding the influences of Atlantic multidecadal oscillation (AMO) and El Niño southern oscillation (ENSO) on regional precipitation extremes and characteristics in the state of Florida is the focus of this study. Exhaustive evaluations of individual and combined influences of these oscillations using, descriptive indices‐based assessment of statistically significant changes in rainfall characteristics, identification of spatially varying influences of oscillations on dry and wet spell transition states, antecedent precipitation prior to extreme events, intraevent temporal distribution of precipitation and changes in temporal occurrences of extremes including dry/wet cycles are carried out. Rain gage and gridded precipitation data analysis using parametric hypothesis tests confirm statistically significant changes in the precipitation characteristics from one phase to another of each oscillation and also in coupled phases. Spatially nonuniform and uniform influences of AMO and ENSO, respectively, on precipitation are evident. AMO influences vary in peninsular and continental parts of Florida and the warm (cool) phase of AMO contributes to increased precipitation extremes during wet (dry) season. The influence of ENSO is confined to dry season with El Niño (La Niña) contributing to increase (decrease) in extremes and total precipitation. Wetter antecedent conditions preceding daily extremes are dominant in AMO warm phase compared to the cool and are likely to impact design floods in the region. AMO influence on dry season precipitation extremes is noted for ENSO neutral years. The two oscillations in different phases modulate each other with seasonal and spatially varying impacts and implications on flood control and water supply in the region.
Effects of westerly wind bursts on El Niño: A new perspective
Authors: Lian Tao , Chen Dake , Tang Youmin , Wu Qiaoyan 
Published: May 2014

AbstractDaily observations from 1971 to 2010 reveal that every El Niño during this period was accompanied by congregated westerly wind bursts, suggesting a close relationship of these bursts with both “cold tongue” and “warm pool” El Niño events. With the addition of burst‐like multiplicative noise to an intermediate ocean‐atmosphere coupled model, it is shown that westerly wind bursts, by generating eastward equatorial surface currents and downwelling Kelvin waves, could be responsible for the existence of the warm pool El Niño and for the irregularity and extremes of the cold tongue El Niño. Whether these bursts give rise to one type of El Nino or the other depends on the timing of their occurrence relative to the phase of the recharge‐discharge cycle of the equatorial upper ocean heat content.
Observation of large‐amplitude magnetosonic waves at dipolarization fronts
Authors: Zhou Meng , Ni Binbin , Huang Shiyong , Deng Xiaohua , Ashour‐Abdalla Maha , Nishimura Yukitoshi , Yuan Zhigang , Pang Ye , Li Huimin 
Published: May 2014

AbstractVarious plasma waves have been observed in the vicinity of dipolarization fronts (DFs) and the rarefaction regions behind them. It was suggested that these waves not only play crucial roles in regulating particle kinetics at the DFs but also may potentially affect the large‐scale dynamics of the magnetotail. In this paper, we present the observations of large‐amplitude electromagnetic waves at DFs that occurred during magnetospheric substorms. The DFs were embedded in either the tailward or earthward flows in the near‐Earth magnetotail. The wave frequencies were near the local proton cyclotron frequency. The waves propagated at highly oblique angles with respect to the ambient magnetic field (~80°–100°). Their corresponding wavelengths were on the order of the local ion gyroradii. The major magnetic field fluctuations were along the background magnetic field, while the electric field fluctuations were predominantly perpendicular to the background magnetic field. The waves were compressional waves as there was an anticorrelation between the plasma density and the wave magnetic field strength. The electric potential associated with the waves reached to more than half of the electron temperature, indicating the waves are nonlinear. We suggest that the waves were magnetosonic or ion Bernstein mode waves driven by the ion ring distribution. The waves were able to provide significant anomalous resistivity at the front, with major contributions from the electric field fluctuations. The effects of these waves on the electron pitch angle scattering and energy diffusion are also discussed.
Messenger
RNA
in Prokaryotes
Authors: Kushner Sidney R 
Published: May 2014

Abstract

Messenger ribonucleic acids (mRNAs)
are molecules that represent the intermediate step in the conversion of genetic information carried in a cell's
deoxyribonucleic acid (DNA)
into functional proteins. They are synthesised by the enzyme RNA polymerase, which recognises specific sequences in the DNA (promoters) to initiate the process called transcription. Downstream sequences, called terminators, provide the signals for transcription to stop. Structural features of mRNAs, such as the presence of a strong ribosome‐binding site (RBS) and appropriate spacing between the RBS and the translation start codon, control both how effectively the information they contain is translated into functional proteins and how rapidly they are decayed. The steady‐state level of each mRNA, which is determined by the rate of its synthesis versus the rate of its decay, helps regulate how much protein is synthesised from each mRNA. mRNA decay in prokaryotes is carried out by a series of nucleases that can either degrade the RNA molecule by cleaving at internal sites or removing one nucleotide at a time from either the 5′ or 3′ terminus.

Key Concepts:

RNA is distinguished from DNA by the presence of ribose instead of deoxyribose and uracil instead of thymine.

Messenger RNAs are required for converting the genetic information in the DNA into functional proteins.

More than one protein can be encoded in a single mRNA.

In prokaryotes mRNAs must have a ribosome binding site in order to be translated.

Secondary and tertiary structures within an mRNA affect its stability and functionality.

Riboswitches help regulate the expression of a large number of genes.

mRNAs are degraded by a variety of ribonucleases.

mRNA decay is carried out by multiprotein complexes in bacteria.

Polyadenylation of mRNAs in bacteria stimulate their degradation.

The translation and stability of many mRNAs are regulated by sRNAs.
Photosynthesis: Ecology
Authors: Dyson Beth , Johnson Giles 
Published: May 2014

Abstract

Photosynthesis is the process by which plants convert light energy into chemical energy for use in growth and cellular repair. The ability of plants to capture light energy, carry out photosynthesis and grow is affected by many environmental factors including temperature, water and nutrient supply. Plants living in natural environments are also subject to competition and shading from other plants and have a number of biochemical and morphological adaptations to increase the efficiency of light absorption, whilst avoiding light stress. Various adaptations of photosynthesis exist that allow plants to tolerate extreme environmental conditions. Ultimately, the overall net photosynthetic rate of ecosystems has a major impact on the global carbon budget. These impacts may be significantly altered by global warming and subsequent climate change.

Key Concepts:

Photosynthesis requires the efficient capture of light whilst avoiding the absorption of damaging excess energy.

Light absorption can be optimised by plant growth, the movement of leaves and the movement of chloroplasts within leaves.

To grow optimally, plants must achieve a balance between the capture of light and the uptake of other resources.

Plants living in shaded conditions have adaptations to efficiently capture light including increased shoot:root ratios, thin leaves and high chlorophyll concentrations.

Two adaptations to C3 photosynthesis exist to optimise water use efficiency: C4 photosynthesis and crassalucean acid metabolism (CAM).

Both C4 and CAM involve a separation of CO
2
absorption and fixation: C4 spatially and CAM temporally.

If a plant is to survive, grow and reproduce, it must make a net gain in carbon, that is, carbon gained through photosynthesis must be greater than carbon lost through respiration.

Photosynthesis makes a significant contribution to carbon uptake from the atmosphere and may go some way to offsetting atmospheric increases due to human activity.

Understanding the effects of global warming on photosynthesis is complex but necessary to fully understand the consequences of climate change.
UV–Vis irradiation fatigue resistance improvement of azo photochromic compound using polyurethane‐chitosan double shell encapsulation
Authors: Fan Fei , Wang Chaoxia 
Published: May 2014

ABSTRACTDouble shell photochromic microcapsules were prepared by in situ polymerization with polyurethane and chitosan as inner and outer shell respectively. FT‐IR indicated that chitosan‐glutaraldehyde copolymer formed by imine and combined with polyurethane photochromic nanocapsules. The polyurethane‐chitosan microcapsules exhibited a near‐spherical shape, and the average particle size of nanocapsules was around 1.2 μm. The half‐life of azo compound increased from 135 to 340 min after encapsulated in polyurethane‐chitosan microcapsules. The polyurethane‐chitosan shell delayed the coloration process for 14 s compared with azo compound in ethanol, however, the absorbance of azo compound increased by 17.15% in polyurethane‐chitosan microcapsules. It decreased from 0.3486 to 0.1738 in ethanol during 20 s, however, it decreased from 0.4084 to 0.2625 in polyurethane‐chitosan microcapsules in 55 s when it reached steady state during decoloration process. Polyurethane‐chitosan double shell encapsulation is an effective route for improving the fatigue resistance, increasing the absorbance of azo compound. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40895.
Comparing cracking time and structure changes of different high‐density polyethylenes during stress and photo‐oxidative aging
Authors: Huang Zhengyu , Li Yongliang , Ren Xiancheng 
Published: May 2014

ABSTRACTThis article describes the structure changes of high‐density polyethylene (HDPE) during stress and photo‐oxidative aging experiments, and the relationship between different materials and cracking time. The three most representative grades of HDPE are 9070, TR480, and 2480NT. The average molecular weight, the comonomer type, and content of materials were measured by high‐temperature gel permeation chromatography, 13C nuclear magnetic resonance (NMR) spectroscopy, and successive self‐nucleation and annealing technique. Moreover, tensile testing was done to distinguish different toughness of materials. The samples were exposed to 5 MPa stress and ultraviolet irradiation in an aging oven, and observed at time intervals. The changes in structure were characterized by metallurgical microscopy, differential scanning calorimetry, attenuated total reflection‐Fourier transform infrared spectroscopy, X‐ray diffraction, and gel content measurements. With increasing time, the crystallinity increased, whereas melting point and oxygen induction times decreased. Meanwhile, the carbonyl index values and gel content reached about 10% until the samples were cracked. The results manifested that the resistance to cracking of the different HDPEs followed the order: 2480NT > TR480 > 9070. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40904.
Effect of inert plasticizers on mechanical, thermal, and sensitivity properties of polyurethane‐based plastic bonded explosives
Authors: Yılmaz Gürkan Atınç , Şen Değer , Kaya Zekeriya Taner , Tinçer Teoman 
Published: May 2014

ABSTRACTMechanical, thermal, and sensitivity properties of plastic bonded explosives (PBX) depend on the type of ingredients in their formulation. Aim of the work is to develop aluminized cast PBX formulations and process conditions by using alternative inert plasticizers to have similar or better properties than PBXN‐109 without compromising sensitivity properties. Although very small portion of total production of plasticizers is used for solid rocket propellant and explosive formulations, they play very significant role in that area. Both inert and energetic plasticizers have involved propellant and explosive formulations to improve process parameters, mechanical properties, and even insensitivity properties of them. Isodecyl pelargonate and dioctyl adipate are the most preferred inert plasticizers in polyurethane based thermoset propellant and explosive formulations. In addition to them, diisononyl adipate and diisononyl phthalate were used and screened as inert plasticizer candidates for aluminized cast PBX formulations. Mechanical, thermal, and sensitivity properties of PBX formulations were studied and compared in detail. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40907.
Encapsulation of animal wax‐based organogels in alginate microparticles
Authors: Sagiri Sai S. , Pal Kunal , Basak Piyali 
Published: May 2014

ABSTRACTEncapsulation of organogels is a novel perspective in the field of controlled drug delivery. This study reports encapsulation of lanolin based organogels within alginate microparticles. The microparticles were prepared by emulsification/internal gelation method. Microscopic studies suggested spherical shape of the microparticles. Fourier transform infrared, X‐ray diffraction and thermal studies confirmed the presence of organogels within the microparticles. Organogels containing microparticles showed improved drug (e.g., salicylic acid and metronidazole) entrapment efficiency. The release of the drugs from the microparticles was dependent on the pH of the dissolution medium. The release was diffusion mediated. The drug loaded microparticles showed antimicrobial activity against E. coli and B. subtilis. The preliminary study suggested that the encapsulation of the organogels may help prolonging the release of the drugs and hence may be tried as vehicles for controlled drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40910.
Stem cell therapy and cellular engineering for treatment of neuronal dysfunction in Huntington's disease
Authors: Choi Kyung‐Ah , Hwang Insik , Park Hang‐soo , Oh Seung‐Ick , Kang Seongman , Hong Sunghoi 
Published: May 2014

AbstractHuntington's disease (HD) is a fatal inherited neurodegenerative disorder characterized by progressive loss of neurons in the striatum, a sub‐cortical region of the forebrain. The sub‐cortical region of the forebrain is associated with the control of movement and behavior, thus HD initially presents with coordination difficulty and cognitive decline. Recent reprogramming technologies, including induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs), have created opportunities to understand the pathological cascades that underlie HD and to develop new treatments for this currently incurable neurological disease. The ultimate objectives of stem cell‐based therapies for HD are to replace lost neurons and to prevent neuronal dysfunction and death. In this review, we examine the current understanding of the molecular and pathological mechanisms involved in HD. We discuss disease modeling with HD‐iPSCs derived from the somatic cells of patients, which could provide an invaluable platform for understanding HD pathogenesis. We speculate about the benefits and drawbacks of using iNSCs as an alternative stem cell source for HD treatment. Finally, we discuss cell culture and engineering systems that promote the directed differentiation of pluripotent stem cell‐derived NSCs into a striatal DARPP32+ GABAergic MSN phenotype for HD. In conclusion, this review summarizes the potentials of cell reprogramming and engineering technologies relevant to the development of cell‐based therapies for HD.
Systematic review of skills transfer after surgical simulation-based training
Authors: Dawe S R , Pena G N , Windsor J A , Broeders J A J L , Cregan P C , Hewett P J , Maddern G J 
Published: May 2014

Abstract

Background
Simulation-based training assumes that skills are directly transferable to the patient-based setting, but few studies have correlated simulated performance with surgical performance.

Methods
A systematic search strategy was undertaken to find studies published since the last systematic review, published in 2007. Inclusion of articles was determined using a predetermined protocol, independent assessment by two reviewers and a final consensus decision. Studies that reported on the use of surgical simulation-based training and assessed the transferability of the acquired skills to a patient-based setting were included.

Results
Twenty-seven randomized clinical trials and seven non-randomized comparative studies were included. Fourteen studies investigated laparoscopic procedures, 13 endoscopic procedures and seven other procedures. These studies provided strong evidence that participants who reached proficiency in simulation-based training performed better in the patient-based setting than their counterparts who did not have simulation-based training. Simulation-based training was equally as effective as patient-based training for colonoscopy, laparoscopic camera navigation and endoscopic sinus surgery in the patient-based setting.

Conclusion
These studies strengthen the evidence that simulation-based training, as part of a structured programme and incorporating predetermined proficiency levels, results in skills transfer to the operative setting.
Micellar electrokinetic chromatographic determination of rosuvastatin in rabbit plasma and evaluation of its pharmacokinetics and interaction with niacin
Authors: El‐Kommos Michael E. , Mohamed Niveen A. , Ali Hassan R. H. , Abdel Hakiem Ahmed F. 
Published: May 2014

ABSTRACTA specific, accurate, precise and reproducible micellar electrokinetic chromatographic method was developed for in vitro and in vivo estimation of rosuvastatin, a synthetic and potent HMG‐CoA inhibitor, in rabbit plasma. Further, its pharmacokinetics in the presence of niacin, which could be co‐administered for monitoring of severe hypercholestremia, was investigated. The assay procedures involved simple liquid–liquid extraction of rosuvastatin and internal standard, atorvastatin, from a small plasma volume directly into acetonitrile. The organic layer was separated and evaporated under a gentle stream of nitrogen. The residue was reconstituted in the mobile phase and injected electrokinetically into electropherosis system. The background electrolyte consisted of borate buffer (25.0 mm, pH 9.5), 10.0% organic modifier (5.0% methanol + 5.0% acetonitrile) and 25.0 mm sodium dodecyl sulfate at 20.0 kV applied voltage and 215.0 nm detection wavelength for the effective separation of rosuvastatin, niacin and atorvastatin. Copyright © 2014 John Wiley & Sons, Ltd.
Binding of caffeic acid to human serum albumin by the retention data and frontal analysis
Authors: An Yuxin , Li Qian , Chen Jiejun , Gao Xiaokang , Chen Hongwei , Xiao Chaoni , Bian Liujiao , Zheng Jianbin , Zhao Xinfeng , Zheng Xiaohui 
Published: May 2014

ABSTRACTA new mathematical model and frontal analysis were used to characterize the binding behavior of caffeic acid to human serum albumin (HSA) based on high‐performance affinity chromatography. The experiments were carried out by injecting various mole amounts of the drug onto an immobilized HSA column. They indicated that caffeic acid has only one type of binding site to HSA on which the association constant was 2.75 × 104/m. The number of the binding site involving the interaction between caffeic acid and HSA was 69 nm. The data obtained by the frontal analysis appeared to present the same results for both the association constant and the number of binding sites. This new model based on the relationship between the mole amounts of injection and capacity factors assists understanding of drug–protein interaction. The proposed model also has the advantages of ligand saving and rapid operation. Copyright © 2014 John Wiley & Sons, Ltd.
Three New Phenylpropanoids from the Roots of Piper taiwanense and Their Inhibitory Activities on Platelet Aggregation and Mycobacterium tuberculosis
Authors: Chen Si , Cheng Ming‐Jen , Wu Chin‐Chung , Peng Chien‐Fang , Huang Hung‐Yi , Chang Hsun‐Shuo , Wang Chyi‐Jia , Chen Ih‐Sheng 
Published: May 2014

AbstractBioassay‐guided fractionation of the active AcOEt‐soluble fraction from the roots of Piper taiwanense has led to the isolation of two new phenylpropanoids, taiwanensols A and B (1 and 2, resp.), a new natural product, taiwanensol C (3), and 3‐acetoxy‐4‐hydroxy‐1‐allylbenzene (4). The compounds were obtained as two isomer mixtures (1/2 and 3/4, resp.). Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. Compounds 1–4 were evaluated for their antiplatelet and antitubercular activities. The mixtures 1/2 and 3/4 showed potent inhibitory activities against platelet aggregation induced by collagen, with IC50 values of 35.2 and 8.8 μM, respectively. In addition, 1/2 and 3/4 showed antitubercular activities against Mycobacterium tuberculosis H37Rv, with MIC values of 30.0 and 48.0 μg/ml, respectively.
ChemInform Abstract: Hexagonal Bipyramidal [Ta2B6]‐/0 Clusters: B6 Rings as Structural Motifs.
Authors: Li Wei‐Li , Xie Lu , Jian Tian , Romanescu Constantin , Huang Xin , Wang Lai‐Sheng 
Published: May 2014

AbstractThe title clusters are obtained by laser ablation of cold‐pressed targets composed of Ta, 11B, and Ag or Bi as binders and calibrants for subsequent photoelectron spectroscopy.