bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure‐based replacement of methionine residues at the catalytic domains with serine significantly improves the oxidative stability of alkaline amylase from alkaliphilic Alkalimonas amylolytica
Authors: Yang Haiquan , Liu Long , Li Jianghua , Du Guocheng , Chen Jian
Published: August 2012

The alkaline amylase requires high resistance towards chemical oxidation for use in the detergent and textile industries. This work aims to improve the oxidative stability of alkaline amylase from alkaliphilic Alkalimonas amylolytica by site‐directed mutagenesis based on the enzyme structure model. Five mutants were created by individually replacing methionine at positions 145, 214, 229, 247, and 317 in the amino acid sequence of alkaline amylase with oxidative‐resistant serine. The pH stability of the mutant enzymes was almost the same as that of the wild‐type (WT) enzyme (pH 7.0–11.0). The stable temperature range of the mutant enzymes M145S and M247S decreased from <50°C of the WT to <40°C, while the thermal stability of the other three mutant enzymes (M214S, M229S, and M317S) was almost the same as that of the WT enzyme. The catalytic efficiency (kcat/Km) of all the mutant enzymes decreased when compared to WT enzyme. The mutant enzymes showed increased activity in the presence of surfactants Tween‐60 and sodium dodecyl sulfate. When incubated with 500 mM H2O2 at 35°C for 5 h, the WT enzyme retained only 13.3% of its original activity, while the mutant enzymes M145S, M214S, M229S, M247S, and M317S retained 55.6, 70.2, 54.2, 62.5, and 46.4% of the original activities, respectively. The results indicated that the substitution of methionine residues at the catalytic domains with oxidative‐resistant serine can significantly improve the oxidative stability of alkaline amylase. This work provides an effective strategy to improve the oxidative stability of amylase, and the high oxidation resistance of the mutant enzymes shows their potential applications in the detergent and textile industries. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
A morphometric study of the celiac trunk and review of the literature
Authors: Venieratos Dionysios , Panagouli Eleni , Lolis Evangelos , Tsaraklis Athanasios , Skandalakis Panagiotis
Published: August 2012

The anatomy of the celiac trunk and its branches was examined in 77 adult human cadavers of Caucasian (Hellenic) origin. The celiac trunk followed the normal pattern, namely trifurcation to the common hepatic, splenic, and left gastric arteries, in 90.9% of the dissections (70/77). Two different types of trifurcation were observed: (a) a true tripod when the celiac trunk ended in a complete trifurcation (74.0%, 57/77) and (b) a false tripod when the three arteries did not have a common origin (16.9%, 13/77). Such a clear predominance of the true tripod is not reported elsewhere. Anatomic variations were found in 9.1% (7/77). Bifurcation of the celiac trunk into splenic and left gastric artery (splenogastric trunk) was observed in one specimen (1.3%), whereas the common hepatic artery emerged directly from the aorta. Absence of the celiac trunk was also found in two individuals (2.6%). The celiac trunk presented additional branches (lumbar and inferior phrenic arteries) in 5.2% (4/77). The median level of origin of the celiac trunk was at the upper third of L1 (22.7% to 17/75). The total length of the celiac trunk ranged from 1.1 to 5.0 cm, whereas the mean length was 2.8 cm (standard deviation = 0.80 cm, standard error of mean = 0.09 cm) irrespective of the existence of variations. The mean length of the celiac arteries which formed a false tripod was found to be larger than those of the arteries which formed a true tripod but only a weak statistically significant difference was established (P = 0.073). Clin. Anat. 26:741–750, 2013. © 2012 Wiley Periodicals, Inc.
The arterial supply of the cervical and thoracic spinal muscles and overlying skin: Anatomical study with implications for surgical wound complications
Authors: Yue Brian Yin Ting , le Roux Cara Michelle , Corlett Russell , De La Harpe David , Richardson Martin , Ashton Mark
Published: August 2012

Postoperative spinal wound dehiscence is a significant complication following the posterior midline approach. It is postulated that this approach disrupts the vasculature supplying the paraspinal muscles and overlying skin. Although the spinal vasculature has been investigated previously, the smaller arterioles have not been described in the context of the posterior midline approach. Eight cadaveric neck and posterior torso specimens were dissected after injection with a radio‐opaque lead oxide mixture and subsequent radiographs taken were analyzed. The deep cervical, vertebral, superficial cervical, and occipital arteries consistently supplied the cervical paraspinal muscles. The latter two arteries also vascularized the overlying skin. The deep cervical arteries were found to be located lateral to the C3 to C6 vertebrae, vulnerable to damage with the posterior approach. In the thoracic region, the superior and posterior intercostal arteries consistently supplied the spinal muscles. In all specimens, two small anastomotic vessels posterior to the laminae were found connecting the intercostal artery perforators. Both the arterial perforators and their anastomotic channels were situated in the surgical field and susceptible to damage with the posterior approach. It is likely that the disruption in spinal vasculature contributes to the multifactorial problem of wound dehiscence with the posterior midline approach. Clin. Anat. 26:584–591, 2013. © 2012 Wiley Periodicals, Inc.
The synovial fold of the distal tibiofibular joint: A morphometric study
Authors: O'Sullivan E. , Bowyer G. , Webb A.L.
Published: August 2012

Impingement of the synovial fold of the distal tibiofibular joint (DTFJ) may contribute to the development of chronic ankle pain and disability after ankle inversion sprain. The morphology of the synovial fold of the DTFJ and recess is poorly understood. The purpose of this study was to describe and quantify the synovial fold and recess of the DTFJ. Thirty‐three pairs of adult embalmed ankle joints were dissected and the presence, disposition, morphology, and dimensions of the synovial fold were determined in relation to the DTFJ and its recess. A synovial fold was present in all specimens examined and extended from the deep posterior tibiofibular ligament along the DTFJ line an average of 15.31 mm [standard deviation (SD), 4.42 mm]. The majority of synovial folds were elongated in shape with smooth borders and occupied more than two thirds of the DTFJ line. In 70% of ankles examined, the synovial folds were found to extend a mean of 20.05 mm (SD, 7.01 mm) from the DTFJ line into the recess where they were loosely attached to the fibular wall. In the remaining ankles, the synovial fold was limited to the DTFJ line leaving the recess devoid of a synovial fold. Intra‐observer and inter‐observer reliability of measurements was good to excellent (intra‐class correlation coefficient, 0.61–0.99). An understanding of the morphology of the DTFJ synovial fold might help to explain ongoing ankle pain after injury, and why arthroscopic removal of the tissue might be therapeutic. Clin. Anat. 26:630–637, 2013. © 2012 Wiley Periodicals, Inc.
Rare coronary anastomoses between the aorta, pulmonary trunk, left coronary artery, and subclavian artery
Authors: Takechi Masaki , Yan Jun , Hitomi Jiro
Published: August 2012

We report a rare case of coronary anastomoses in an 83‐year‐old male cadaveric heart. Anomalous vessels arose from the right sinus of the aorta, left main coronary artery, left anterior descending artery, left anterior medial atrial artery, and left subclavian artery. These vessels bifurcated and anastomosed, and finally connected to the pulmonary trunk. The present case is categorized as a multilateral coronary artery fistula in cardiology. Clin. Anat. 25:969–972, 2012. © 2012 Wiley Periodicals, Inc.
Venous architecture of the glabellar to the forehead region
Authors: Shimizu Yusuke , Imanishi Nobuaki , Nakajima Tatsuo , Nakajima Hideo , Aiso Sadakazu , Kishi Kazuo
Published: August 2012

The precise venous anatomy of the glabellar to the forehead region remains unknown. This study aimed to detail the venous architecture of the glabellar region to the forehead in conjunction with that of the supratrochlear artery to reduce the risk of venous congestion of flaps in this area. Fifteen fresh human cadavers were examined here. In five specimens, contrast medium was injected only into the venous system; in 10 specimens, two different types of contrast media were injected into the arterial and venous systems, respectively. A total of 30 hemifacial specimens were radiographed stereoscopically and observed microscopically. In all the cadavers, a distinct vein (termed as the “transverse nasal root vein”) connected the bilateral angular veins. One or two large ascending veins branched from the transverse nasal root or angular vein, coursing toward the forehead skin. Numerous small veins branched out from the large ascending vein(s), forming a subdermal polygonal venous network. Small ascending veins arose from this network and coursed toward the dermis, draining venous flow from the dermis. Three different‐sized valves prevented the reflux of blood in the venous pathway. The large ascending vein(s) and supratrochlear artery ran parallel only in the medial canthal area. Tiny venous vasa vasorum surrounded the adventitia of the supratrochlear artery and anastomosed with the polygonal venous network, while a few small veins from the vasa vasorum ascended toward the dermis. Understanding the venous architecture of this region is expected to facilitate the safe elevation of various flaps in the area. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.
Tullio Terni (1888–1946): The “column” of spinal cardiovascular regulation
Authors: Macchi V. , Porzionato A. , Stecco C. , De Caro R.
Published: August 2012

Tullio Terni (1888–1946) was a brilliant anatomist in the School of Medicine of Padova, Italy. He was a versatile scientist who gave fundamental and pioneering contributions in descriptive and experimental cytology, human and comparative morphogenesis, neuroanatomy, embryology and teratology, and regenerative biology. His most famous discovery, which bears his name, is the so‐called “Terni's column.” In embryos of chickens, he described the existence in the thoracolumbar region of the spinal cord of a preganglionic nervous center, constituting a longitudinal column of nervous cells between the first thoracic and the second lumbar segments. Tullio Terni embodied the ideal of free science without geographic boundaries. He used cutting‐edge tools, demonstrating his very current approach. Terni studied the organization of tissues and organs and the spatial arrangement and the physical state of the tissues of living systems. He also practiced experimental embryology, which formed the basis of modern techniques in organ transplantation. Moreover, he studied multiple species in order to compare multiple organisms. Terni was a multifaceted scientist. Clin. Anat. 26:544–546, 2013. © 2012 Wiley Periodicals, Inc.
Analysis of neurosensory adverse events induced by FOLFOX4 treatment in colorectal cancer patients: a comparison between two Asian studies and four Western studies
Authors: Sugihara Kenichi , Ohtsu Atsushi , Shimada Yasuhiro , Mizunuma Nobuyuki , Gomi Katsushige , Lee Po‐Huang , de Gramont Aimery , Rothenberg Mace L. , André Thierry , Brienza Silvano , Goldberg Richard M.
Published: August 2012

The grades of neurosensory adverse events (NSAEs) induced by FOLFOX4 treatment were compared between Asian and Western colorectal cancer patients and correlated with cumulative oxaliplatin doses. A total of 3359 patients treated with FOLFOX4 were analyzed: 1515 from two Asian studies (Japanese Post Marketing Surveillance [J‐PMS] and MASCOT) and 1844 from four Western studies (EFC2962, N9741, EFC4584, and MOSAIC). The onset of NSAEs was analyzed in terms of treatment duration and cumulative dose of oxaliplatin. The incidence of grade ≥3 NSAEs ranged from 2.0% to 4.4% in Asian studies and 9.3% to 19% in Western studies. The cumulative doses of oxaliplatin that induced grade ≥3 NSAEs in 10% of patients were higher in Asian studies (1526 mg/m2 or not reached) than in Western studies (805–832 mg/m2). No significant correlations were noted between occurrence of grade ≥3 NSAEs and demographic/baseline characteristics. The frequency of escalation from grade 0 to 1 in J‐PMS was statistically significantly lower than that in EFC4584, and that from grade 0 to 1 and from grade 1 to 2 in MASCOT lower than that in MOSAIC. The cumulative oxaliplatin doses administered during grade escalation in J‐PMS were similar to those in EFC2962 or EFC4584. All grade‐3 NSAEs in MASCOT and 96% of those in MOSAIC improved to grade 2 or less within 12 months of follow‐up. The Asian populations accrued to these studies appear to be less susceptible to the neurotoxicity of oxaliplatin than the mainly Caucasian populations in the Western studies.
Modification of the siRNA Passenger Strand by 5‐Nitroindole Dramatically Reduces its Off‐Target Effects
Authors: Zhang Junbin , Zheng Jie , Lu Chang , Du Quan , Liang Zicai , Xi Zhen
Published: August 2012

During the formation of RNA‐induced silencing complex (RISC), the passenger and guide strand of an siRNA duplex separate from each other to generate an active RISC complex. Accumulating evidence shows that an siRNA passenger strand can also assemble into a RISC complex and mediate RNA interference, thereby causing undesired off‐target effects. To reduce this effect, the so‐called “universal base” 5‐nitroindole nucleotides were incorporated into an siRNA passenger strand. Melting temperature and circular dichroism spectrum measurements showed no significant changes compared to the unmodified duplex, thus indicating the formation of normal A‐form conformation. Using a dual luciferase reporter assay, we have further shown that 5‐nitroindole modification at position 15 of the siRNA passenger strand drastically decreased the RNAi (RNA interfering) potency of this strand, whereas the potency of the RNA guide strand was not much affected. These results could provide a practical approach for reducing off‐target effects mediated by the siRNA passenger strand.
Tethering of Dinuclear Complexes to SBA‐15 and Their Application in CO2 Hydrogenation
Authors: Morgan Grace G. , Fennell Kevin , Kishore M. Jhansi L. , Sullivan James A.
Published: August 2012

Two bimetallic cryptates (containing Cu and Co), which have previously been shown to react with and activate atmospheric CO2, were tethered to modified mesoporous SiO2 and their activities in promoting the CO2+H2 reaction has been analysed. The cryptates were tethered to C3H6Cl‐modified SBA‐15 through a condensation reaction between surface alkyl chlorides and 2° amines of the ligands, which released HCl and formed 3° amine linkages. The materials were characterised using BET, thermogravimetric analysis, FTIR and elemental analysis and their activities in promoting the CO2+H2 reaction was tested under batch reactor conditions. Co ions appear to selectively populate the medal sites of the tethered ligands whereas Cu ions appear to deposit on the surface as Cu(BF4)2 salts. The composite materials generate CO and CH4 from the CO2+H2 mixtures. Co‐containing catalysts are more effective than their Cu analogues in promoting the reaction.
Click Chemistry of Alkyne–Azide Cycloaddition using Nanostructured Copper Catalysts
Authors: Jin Tienan , Yan Mei , Yamamoto Yoshinori
Published: August 2012

With increasing advances on nanotechnology, the nanostructured copper catalysts have attracted much attention in alkyne–azide click reaction in the last few years owing to their large surface area, tunable morphology and sustainable catalytic activities. Supported copper nanoparticles are most widely employed. The shape, size and dispersity of supported copper nanoparticles are highly controlled by the used supports, as these will determine the catalytic activity of the heterogeneous click reaction. On the other hand, nanoporous coppers with specific three‐dimensional open pore network structure was reported most recently, which can be fabricated with a tunable ligament or pore size without any supports, exhibiting high catalytic activity and reusability. This Minireview describes the state of the art with respect to the fabrication and catalytic application of both supported copper nanoparticles and nanoporous copper in click reaction.
Decentralized Control System Design for a Ternary Reactive Distillation with Inert Using Mixed Integer Optimization
Authors: Paramasivan G. , Kienle A.
Published: August 2012

Inferential control of ternary reactive distillation with inert is controversially discussed in recent literature. For further clarification, a systematic study based on mixed integer dynamic optimization is presented. Special emphasis is placed on robustness with respect to various disturbances arising in practice. This gives rise to a stochastic problem formulation which is extended step by step. Through this, significant improvements can be achieved and it is concluded that inferential control of ternary reactive distillation with inert is feasible.
NMR Spin–Spin Coupling Constants in Polymethine Dyes as Polarity Indicators
Authors: Murugan N. Arul , Aidas Kestutis , Kongsted Jacob , Rinkevicius Zilvinas , Ågren Hans
Published: August 2012

Herein, we explore the use of spin–spin coupling constants (SSCCs) in merocyanine (MCYNE) dyes as indicators of polarity. For this purpose, we use Car–Parrinello hybrid quantum mechanics/molecular mechanics (QM/MM) to determine the structures of MCYNE in solvents of different polarity, followed by computations of the SSCCs by using QM/MM linear‐response theory. The molecular geometry of MCYNE switches between neutral, cyanine‐like, and zwitterionic depending on the polarity of the solvent. This structural variation is clearly reflected in the proton SSCCs in the polymethine backbone, which are highly sensitive to the dielectric nature of the environment; this mechanism can be used as a “polarity indicator” for different microenvironments. This result is highlighted by computing the SSCCs of the MCYNE probe in the cavity of the beta‐lactoglobulin protein. The computed SSCCs clearly indicate a non‐polar hydrophobic dielectric nature of this cavity.
Use of Melem as a Nucleophilic Reagent to Form the Triphthalimide C6N7(phthal)3—New Targets and Prospects
Authors: Schwarzer Anke , Böhme Uwe , Kroke Edwin
Published: August 2012

Melem (1), as one of the most important representatives of the tri‐s‐triazine compounds, can be used as a nucleophilic reagent in reactions with phthalic acid derivatives. The synthesis of 2,5,8‐triphthalimido‐tri‐s‐triazine (C6N7(phthal)3, 2) was investigated starting from phthalic anhydride or phthalic dichloride in various solvents, at different temperatures as well as in the solid state. NMR measurements (solution and solid state), IR spectroscopy and elemental analysis indicated the formation of a cyclic imide. Single‐crystal structure analysis of a 1:1 adduct of 2 with nitromethane proved the molecular structure expected for a phthalimido‐s‐heptazine. DFT calculations were performed to obtain a better insight into the structural features of compound 2, especially the interaction of the carbonyl groups with the tri‐s‐triazine nitrogen atoms. The title compound 2 shows promising properties: it is thermally stable up to 500 °C in air and shows strong photoluminescence with a maximum emission at around 500 nm. The potential of the nucleophilic reaction of melem with other strong electrophiles provides new targets and prospects.
Incorporating Zn2SnO4 Quantum Dots and Aggregates for Enhanced Performance in Dye‐Sensitized ZnO Solar Cells
Authors: Li Yafeng , Wang Ya , Chen Caiyun , Pang Aiying , Wei Mingdeng
Published: August 2012

The performance of dye‐sensitized ZnO solar cells was improved by a facile surface‐treatment approach through chemical‐bath deposition. After the surface treatment, the quantum dots of Zn2SnO4 were deposited onto ZnO nanoparticles accompanied by the aggregations of Zn2SnO4 nanoparticles. The ZnO film displayed a better resistance to acidic dye solution on account of the deposited Zn2SnO4 nanoparticles. Meanwhile, the open‐circuit photovoltage was greatly enhanced, which can be ascribed to the increased conduction‐band edge of ZnO and inhibited interfacial charge recombination. Although the deposition of Zn2SnO4 decreased the adsorption amounts of N719 dye, the aggregates of Zn2SnO4 with a size of 350–450 nm acted as the effective light‐scattering layer, thereby resulting in an improved short‐circuit photocurrent. By co‐sensitizing 10 μm‐thick ZnO film with N719 and D131 dyes, a top efficiency of 4.38 % was achieved under the illumination of one sun (AM 1.5, 100 mW cm−2).
Hydrophilic, Upconverting, Multicolor, Lanthanide‐Doped NaGdF4 Nanocrystals as Potential Multifunctional Bioprobes
Authors: Li Feifei , Li Chunguang , Liu Xiaomin , Chen Ying , Bai Tianyu , Wang Long , Shi Zhan , Feng Shouhua
Published: August 2012

Monodisperse water‐soluble hexagonal phase Ln3+‐doped NaGdF4 upconverting nanocrystals (UCNCs) have been successfully fabricated by means of a fast, facile, and environmentally friendly microwave‐assisted route with polyethylenimine as the surfactant. Fine‐tuning of the UC emission from visible to near‐IR and finally to white light has been achieved. Furthermore, studies of the magnetic resonance imaging as well as the magnetization (magnetization–magnetic field curves) and the targeted recognition properties of FA‐coupled amine‐functionalized NaGdF4@SiO2 UCNCs indicate that the obtained NaGdF4 UCNCs can be potential candidates for dual‐mode optical/magnetic bioapplications.
N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene
Authors: Alvarado Edwin , Badaj Anna C. , Larocque Timothy G. , Lavoie Gino G.
Published: August 2012

Gold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^ImineR), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^ImineR and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^ImineR and S^ImineR gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^IminetBu with [AuCl(SMe2)] led to the formation of [(C^IminetBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^IminetBu)2Au]+, with AuCl2− as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^IminetBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.
Proteasom‐Inhibitoren
Authors: Steverding Dietmar
Published: August 2012

Das Proteasom ist ein multikatalytischer Proteasekomplex mit einem ungewöhnlichen Enzymmechanismus. Es spielt eine zentrale Rolle beim intrazellulären Proteinabbau und seine entscheidende Funktion in der Regulation des Zellzyklus macht es zu einem interessanten Ziel in der Krebstherapie. Zunächst als Reagenzien zur Aufklärung der katalytischen Funktionen des Proteasoms entwickelt, werden mittlerweile einige Proteasom‐Inhibitoren als Krebsmittel in klinischen Studien getestet. Besonders wirkungsvoll als Krebsmittel scheinen Proteasom‐Inhibitoren aus den Substanzklassen der Peptid‐Borsäuren, der Peptid‐Epoxyketone und der γ‐Lactam‐β‐lactone zu sein.
Eine Rinde erobert die Welt
Authors: Streller Sabine , Roth Klaus
Published: August 2012

Die chininhaltige Rinde von Cinchona war das wohl wertvollste Heilmittel, das uns die Neue Welt geschenkt hat. Über Jahrhunderte war dies die einzige Medizin gegen Malaria und wird auch heute noch dafür eingesetzt. Die Isolierung, Strukturbestimmung und Totalsynthese des Chinins waren chemische Meisterstücke. Heute werden mit Cinchona‐Alkaloiden nicht nur verschiedene Krankheiten behandelt, sondern sie dienen als wirkungsvolle Katalysatoren und Hilfsstoffe zur Herstellung reiner Enantiomere in der Chemischen und Pharmazeutischen Industrie. Schließlich verleiht eine kleine Prise Chinin dem Tonic Water und einigen klassischen Cocktails das gewisse Etwas, das wir so genießen. Also, Prost auf alle Drinks, die dieses wunderbare Alkaloid enthalten, egal ob gerührt oder geschüttelt.
Feuerwerk
Authors: Keller Fritz
Published: August 2012

Die Feuerwerkerei bzw. Pyrotechnik ist eine alte empirische Wissenschaft im Grenzbereich zwischen Chemie, Technik, Verfahrenstechnik und Kunst und hat ihren festen Platz bei vielen Events in Kultur und Brauchtum. Im Artikel wird dargestellt, welche Schritte ein Feuerwerk von der Chemie bis zur Show durchläuft. Einige chemische Grundlagen, Informationen zu pyrotechnischen Sätzen wie Schwarzpulver, Leuchtsätzen, oszillierenden Blink‐ und Pfeifsätzen werden erläutert und an Beispielen Aufbau und Herstellung von Feuerwerkskörpern in Text und Bild dargestellt. Aspekte der Sicherheit bei der Herstellung und bei Aufbau und Abbrennen eines Großfeuerwerks werden ebenso behandelt wie die neusten Entwicklungen in der Gesetzgebung, wie Pyrotechnikrichtlinie, CE‐Normung und REACH. Wenn auch das kommerzielle Umfeld der Feuerwerkerei schwieriger wird, bleibt die Faszination für die Phänomene des Feuerwerks ungebrochen und lässt für den Leser vielleicht die Motivation entstehen, sich mit dem spannenden Gebiet der Pyrotechnik und den angrenzenden Wissenschaften näher zu befassen.
Modelling of multicomponent gas separation with asymmetric hollow fibre membranes—methane enrichment from biogas
Authors: Kundu Prodip K. , Chakma Amit , Feng Xianshe
Published: August 2012

A mathematical model for the dynamic performance of gas separation with high flux, asymmetric hollow fibre membranes was developed considering the permeate pressure build‐up inside the fibre bore and cross flow pattern with respect to the membrane skin. The solution technique provides reliable examination of pressure and concentration profiles along the permeator length (both residue/permeate streams) with minimal effort. The proposed simulation model and scheme were validated with experimental data of gas separation from literature. The model and solution technique were applied to investigate dynamic performance of several membrane module configurations for methane recovery from biogas (landfill gas or digester gas), considering biogas as a mixture of CO2, N2 and CH4. Recycle ratio plays a crucial role, and optimum recycle ratio vital for the retentate recycle to permeate and permeate recycle to feed operation was found. From the concept of two recycle operations, complexities involved in the design and operation of continuous membrane column were simplified. Membrane permselectivity required for a targeted separation to produce pipeline quality natural gas by methane‐selective or nitrogen‐selective membranes was calculated. © 2012 Canadian Society for Chemical Engineering
Characteristics of fluidisation behaviour in a pressurised bubbling fluidised bed
Authors: Li Haoyu , Yan Weiping , Wu Wei , Wang Chunbo
Published: August 2012

The experiments were carried out in a bench‐scale fluidised bed of 90 mm in diameter to determine the influence of pressure on fluidisation characteristics of Geldart A and B particles over the range of pressure 0.1–4.5 MPa. For Geldart B particles, the results indicate that minimum fluidisation velocity (umf) was found to decrease with pressure whilst bed voidage at umf was unaffected, and the bed expansion height increase with pressure at fixed value of gas velocity was observed for both Geldart B and A particles. For Geldart A particles, minimum bubbling velocity (umb) bed voidage at umb and dense phase voidage were found to increase obviously with pressure, but a slight influence of pressure on umf was observed. The prediction values of high‐pressure fluidisation characteristics from the references' correlations developed at pressure were in agreement with the experimental data. © 2012 Canadian Society for Chemical Engineering
Degradation of an Azo Dye with Homogeneous and Heterogeneous Catalysts by Sonophotolysis
Authors: Eren Zeynep
Published: August 2012

This study illustrates the degradation of an azo dye, Reactive Yellow 81 (RY81), by the combined irradiation of UV‐C and ultrasound in the presence of homogeneous (Fe2+) and heterogeneous (TiO2, ZnO) catalysts. The efficiency of homogeneous and heterogeneous oxidation systems was evaluated in regard of the decolorization and mineralization of RY81. Decolorization followed pseudo‐first‐order kinetics with homogeneous and heterogeneous catalysts. Complete color removal was accomplished by homogeneous sonocatalytic and sonophotocatalytic oxidation processes with apparent rate constants of 0.96 × 10−3 and 46.77 × 10−3 s−1, respectively, in the presence of Fe2+. However, partial color removal was obtained by heterogeneous sonocatalytic, photocatalytic, and sonophotocatalytic oxidation processes with apparent rate constants of 2.32 × 10−3, 3.60 × 10−3, and 3.67 × 10−3 s−1, respectively, in the presence of ZnO. TiO2 had the worst catalytic effect of all of the oxidation processes. The addition of hydrogen peroxide increased the rate constants of the heterogeneous oxidation processes and decreased the rate constants of the homogeneous oxidation processes. RY81 mineralization was 62.8% for the US/UV/Fe2+ homogeneous oxidation process, which was the best oxidation process, whereas it was 43.5% for the US/UV/ZnO/H2O2 heterogeneous oxidation process within 2 h reaction time.
A Study: Removal of Cu(II), Cd(II), and Pb(II) Ions from Real Industrial Water and Contaminated Water Using Activated Sludge Biomass
Authors: Kusvuran Erdal , Yildirim Deniz , Samil Ali , Gulnaz Osman
Published: August 2012

This study aims to remove of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass were optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS biomass (qmax) were calculated as 0.478, 0.358, and 0.280 mmol g−1 for Cu2+, Cd2+, and Pb2+, respectively, and the adsorption equilibrium time was found as 60 min for each metal. The adsorbed amount of metal rose with increasing of initial metal ion concentration. The equilibrium adsorption capacity of AS for initial 0.25 mmol L−1 metal concentration was determined as 0.200, 0.167, and 0.155 mmol g−1 for Cu2+, Cd2+, and Pb2+ ions, respectively. These relevant values were determined as 0.420, 0.305, and 0.282 mmol g−1 for Cu2+, Cd2+, and Pb2+ ions, respectively, when initial metal concentration was 0.50 mmol L−1. In the multi‐metal sorption system, the adsorption capacity of AS biomass was observed in the order of Cu2+ > Cd2+ > Pb2+. In the presence of 100 mmol L−1 H+ ion, the order of ion‐exchange affinity with H+ was found as Cu2+ > Cd2+ > Pb2+. The adsorption kinetics were also found to be well described by the pseudo‐second‐order and intraparticle diffusion models. Two different rate constants were obtained as ki1 and ki2 and ki1 (first stage) was found to be higher than ki2 (second stage).
Surficial and Vertical Distribution of Heavy Metals in Different Estuary Wetlands in the Pearl River, South China
Authors: Zhang Honggang , Cui Baoshan , Zhang Kejiang
Published: August 2012

A total of 87 soil profiles sampled from five types of wetlands in the Pearl River estuary were analyzed to investigate the surficial and vertical distributions of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). The results show that wetlands directly connected with rivers (e.g., riparian wetlands, estuarine wetlands, and mangrove wetlands) has much higher metal concentrations than those indirectly connected with rivers (e.g., pond wetlands and reclaimed wetlands). The river water is the major pollution source for all investigated heavy metals. The vertical distribution of heavy metals can be classified into three patterns: (i) linear distribution pattern. The concentration of heavy metals gradually decreases with an increase in soil depth (for riparian and estuarine wetlands); (ii) irregular and stable pattern (for pond and reclaimed wetlands); and (iii) middle enrichment pattern (for mangrove wetlands). In addition to river‐borne inputs, a variety of vegetation composition, hydraulic conditions, and human activities also contribute to the variation in distribution of heavy metals in different wetlands. Soil properties (e.g., particle size, pH, salinity, and SOM) also affect the distribution of trace metals in each soil layer. The major pollution source of heavy metals is industrial wastewater. Other sources include agriculture and domestic premises, and atmospheric deposition. This study provides a sound basis for the risk assessment of heavy metals in the studied wetlands and for wetland conservation in general.
Nitrate–Nitrogen Transport in Horizontal Soil Columns of the Yellow River Delta Wetland, China
Authors: Bai Junhong , Ye Xiaofei , Zhi Yuan , Gao Haifeng , Huang Laibin , Xiao Rong , Shao Hongbo
Published: August 2012

Horizontal movement of nitrate–nitrogen was simulated in horizontal soil columns from a typical tidal flooding wetland and a short‐term flooding wetland of the Yellow River Delta. The primary objectives of this study were to investigate the changes in transport fluxes of nitrate–nitrogen with increasing movement distances and to identify the relationship between transport fluxes of nitrate–nitrogen and water diffusion coefficients. The results showed that the transport fluxes of nitrate–nitrogen were significantly and negatively correlated with movement distances in both wetlands, and decreased exponentially with increasing distances. However, the transport fluxes of nitrate–nitrogen increased exponentially with increasing water diffusion coefficients in both wetlands. The higher transport fluxes of nitrate–nitrogen in surface soils were observed compared to deeper soils, while they were higher in surface soils at the distances near the tracer water head. The findings of this study can contribute to water quality protection by regulating buffer zone width based on the horizontal movement of nitrate–nitrogen.
Trafficking of Intermediate (KCa3.1) and Small (KCa2.x) Conductance, Ca2+‐Activated K+ Channels: a Novel Target for Medicinal Chemistry Efforts?
Authors: Balut Corina M. , Hamilton Kirk L. , Devor Daniel C.
Published: August 2012

Ca2+‐activated K+ (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro‐domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein–protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.
BRAF mutation detection in indeterminate thyroid cytology specimens
Authors: Ohori N. Paul , Singhal Rashi , Nikiforova Marina N. , Yip Linwah , Schoedel Karen E. , Coyne Christopher , McCoy Kelly L. , LeBeau Shane O. , Hodak Steven P. , Carty Sally E. , Nikiforov Yuri E.
Published: August 2012

BACKGROUND:

BRAF mutations are highly specific for papillary thyroid carcinoma (PTC) and many cytology specimens with BRAF mutations are expected to demonstrate cytologic features typical of PTC. However, indeterminate thyroid cytology cases are inevitable and understanding the significance of the BRAF mutation within the context of the Bethesda System for Reporting Thyroid Cytopathology would be valuable.

METHODS:

Thyroid cytology cases submitted for conventional cytomorphologic evaluation and BRAF mutational analyses were selected from the authors' cytopathology files from April 2007 to October 2011. From this group, the diagnostic usefulness of BRAF mutations in indeterminate and malignant cases was assessed and analyses of cytologic and histopathologic features associated with the mutations in this gene were performed.

RESULTS:

A total of 131 cases with a BRAF mutation were identified. Of these, 119 underwent surgical pathology resection follow‐up and demonstrated PTC. Approximately 75% of the cases were cytologically diagnosed as being positive for malignancy and these cases were associated with both the classic and tall cell variants of PTC at the time of resection, a greater likelihood of extrathyroidal extension, and the V600E type of BRAF mutation. In contrast, BRAF‐mutated cases with diagnoses of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and follicular neoplasm/suspicious for follicular neoplasm were found to be more strongly associated with the follicular variant of PTC, a K601E BRAF mutation, and a lower likelihood of extrathyroidal extension. However, a subset of AUS/FLUS cases with the V600E BRAF mutation appeared to represent sampling variability of the classic or tall cell variants of PTC.

CONCLUSIONS:

Bethesda thyroid diagnoses in the setting of a BRAF mutation reflect differences in PTC subtypes, the nature of cytology specimens, and molecular characteristics. Cancer (Cancer Cytopathol) 2013;121:197–205. © 2012 American Cancer Society.
Unusual Regioselective Electrophilic Substitutions in Quinoline Foldamers: Conceptual DFT and Frontier Molecular Orbital Analysis Reveal the Crucial Role of Folding and Substituents
Authors: Shravani Madishetti , Balaiah Shanigaram , Srinivas Kolupula , Bhanuprakash K. , Huc Ivan
Published: August 2012

We carried out a detailed computational investigation of an earlier experimentally observed, unusual, regioselective, electrophilic halogenation in helically folded quinoline oligoamides. In the experimental studies, halogenation occurred selectively at a given monomer of a foldamer substituted with electron‐withdrawing groups at the N terminus, although apparently identical reactive sites were available to react with the incoming electrophile. On the other hand, the selectivity was lost with weakly electron‐donating groups. To gain an insight into the regioselective preference of bromination in quinoline foldamers, conceptual DFT was used to calculate the local nucleophilicity index of various foldamers of different sizes and with different substituents, and it was found that the predicted reaction centers were in line with the experimental results. Frontier molecular orbital analysis was used to understand this behavior. A detailed study of the hypothetical linear conformation of the tetramer for comparison with the folded conformation was carried out. In the case of a linear conformer, the HOMO is localized on specific monomers irrespective of substitution, but upon folding delocalization is observed, which is larger for the weakly electron‐donating groups when compared with the electron‐withdrawing groups. In the case of strongly donating groups there is no delocalization, even upon folding. The behavior remains the same when the size of the helix is increased (octamer). Thus, it is clearly seen in this work that the combined effects of conformations and substituents dictate the regioselectivity in the folded oligoamides; this knowledge will have a profound effect on the field of foldamer chemistry.
Two‐Photon Absorption and Time‐Resolved Stimulated Emission Depletion Spectroscopy of a New Fluorenyl Derivative
Authors: Belfield Kevin D. , Bondar Mykhailo V. , Morales Alma R. , Yue Xiling , Luchita Gheorghe , Przhonska Olga V. , Kachkovsky Olexy D.
Published: August 2012

The synthesis, comprehensive linear photophysical characterization, two‐photon absorption (2PA), steady‐state and time‐resolved stimulated emission depletion properties of a new fluorene derivative, (E)‐1‐(2‐(di‐p‐tolylamino)‐9,9‐diethyl‐9H‐fluoren‐7‐yl)‐3‐(thiophen‐2‐yl)prop‐2‐en‐1‐one (1), are reported. The primary linear spectral properties, including excitation anisotropy, fluorescence lifetimes, and photostability, were investigated in a number of aprotic solvents at room temperature. The degenerate 2PA spectra of 1 were obtained with open‐aperture Z‐scan and two‐photon induced fluorescence methods, using a 1 kHz femtosecond laser system, and maximum 2PA cross‐sections of ∼400–600 GM were obtained. The nature of the electronic absorption processes in 1 was investigated by DFT‐based quantum chemical methods implemented in the Gaussian 09 program. The one‐ and two‐photon stimulated emission spectra of 1 were measured over a broad spectral range using a femtosecond pump–probe‐based fluorescence quenching technique, while a new methodology for time‐resolved fluorescence emission spectroscopy is proposed. An effective application of 1 in fluorescence bioimaging was demonstrated by means of one‐ and two‐photon fluorescence microscopy images of HCT 116 cells containing dye encapsulated micelles.
Facile electrochemical synthesis of tellurium nanorods and their photoconductive properties
Authors: Li H. H. , Zhang P. , Liang C. L. , Yang J. , Zhou M. , Lu X. H. , Hope G. A.
Published: August 2012

Tellurium nanorods have been successfully fabricated by template and surfactant‐free electrochemical technique from an aqueous solution at room temperature. The as‐prepared tellurium nanorods were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry, UV‐vis spectroscopy and photoluminescence spectroscopy. Films based on tellurium nanorods were constructed to study the photoresponse and I‐V curves. These photoresponse measurements demonstrate that tellurium nanorods exhibited enhanced conductivity under illumination compared to in the dark measurement.
Supportless Silver Nanowires as Oxygen Reduction Reaction Catalysts for Hydroxide‐Exchange Membrane Fuel Cells
Authors: Alia Shaun M. , Duong Kathlynne , Liu Toby , Jensen Kurt , Yan Yushan
Published: August 2012

Silver nanowires (AgNWs) and nanoparticles (AgNPs) have been synthesized to facilitate hydroxide‐exchange membrane fuel cell development and commercialization. AgNWs and AgNPs with variable diameters (25–60 nm AgNWs, 2.4–30 nm AgNPs) have been studied with rotating‐disk electrode experiments to examine the impact of size and morphology on the oxygen reduction reaction (ORR). Although a detrimental particle size effect is observed, AgNWs exceed the specific activity of bulk polycrystalline Ag. AgNWs with a diameter of 25 nm further exceed the ORR specific and mass activity of 2.4 nm AgNPs 5.3 times and by 16 %, respectively. Rotating ring‐disk electrode testing demonstrates minimal peroxide formation on AgNWs; peroxide production increases with the use of AgNPs by as much as an order of magnitude and further increases with particle size reduction. Silver catalysts demonstrate alcohol tolerance for ORR, illustrating the benefit of silver and AgNWs as catalysts in hydroxide and alcohol hydroxide‐based fuel cells.
2‐Methyltetrahydrofuran (2‐MeTHF): A Biomass‐Derived Solvent with Broad Application in Organic Chemistry
Authors: Pace Vittorio , Hoyos Pilar , Castoldi Laura , Domínguez de María Pablo , Alcántara Andrés R.
Published: August 2012

2‐Methyl‐tetrahydrofuran (2‐MeTHF) can be derived from renewable resources (e.g., furfural or levulinic acid) and is a promising alternative solvent in the search for environmentally benign synthesis strategies. Its physical and chemical properties, such as its low miscibility with water, boiling point, remarkable stability compared to other cyclic‐based solvents such as THF, and others make it appealing for applications in syntheses involving organometallics, organocatalysis, and biotransformations or for processing lignocellulosic materials. Interestingly, a significant number of industries have also started to assess 2‐MeTHF in several synthetic procedures, often with excellent results and prospects. Likewise, preliminary toxicology assessments suggest that the use of 2‐MeTHF might even be extended to more processes in pharmaceutical chemistry. This Minireview describes the properties of 2‐MeTHF, the state‐of‐the‐art of its use in synthesis, and covers several outstanding examples of its application from both industry and academia.
A Simple One‐Pot Dehydration Process to Convert N‐acetyl‐D‐glucosamine into a Nitrogen‐Containing Compound, 3‐acetamido‐5‐acetylfuran
Authors: Omari Khaled W. , Dodot Linda , Kerton Francesca M.
Published: August 2012

An efficient process for converting N‐acetyglucosamine (NAG) into 3‐acetamido‐5‐acetylfuran (3A5AF) is reported. 3A5AF is proposed as an N‐containing platform chemical, which contains renewable nitrogen. In the reported method NAG, in the presence of boric acid (B(OH)3) and sodium chloride (NaCl), produces 58 % yield 3A5AF in dimethylacetamide under microwave irradiation (220 °C, 15 min). A maximum yield of 62 % was obtained in the presence of 4 equivalent NaCl. Performing ICP–MS analysis on NAG from different chemical suppliers highlighted the importance of Cl and B levels in this process. Trace impurities are, therefore, important considerations in biomass transformations. This solution‐phase process produces approximately 30 times more 3A5AF than a pyrolysis route reported previously.
Specific CD8+T cells recognize human herpesvirus 6B
Authors: Martin Larissa K. , Schub Andrea , Dillinger Stefan , Moosmann Andreas
Published: August 2012

The importance of human herpesvirus 6 (HHV‐6) species as human pathogens is increasingly appreciated. However, we do not understand how infection is controlled in healthy virus carriers, and why control fails in patients with disease. Other persistent viruses are under continuous surveillance by antigen‐specific T cells, and specific T‐cell repertoires have been well characterized for some of them. In contrast, knowledge on HHV‐6‐specific T‐cell responses is limited, and missing for CD8+ T cells. Here we identify CD8+ T‐cell responses to HHV‐6B, the most widespread HHV‐6 species, in healthy virus carriers. HHV‐6B‐specific CD8+ T‐cell lines and clones recognized HLA‐A2‐restricted peptides from the viral structural proteins U54 and U11, and displayed various antigen‐specific antiviral effector functions. These CD8+ T cells specifically recognized HHV‐6B‐infected primary CD4+ T cells in an HLA‐restricted manner, produced antiviral cytokines, and killed infected cells, whereas HHV‐6A‐infected cells were not recognized. Thus, HHV‐6B‐specific CD8+ T cells are likely to contribute to control of infection, overcoming the immunomodulatory effects exerted by the virus. Potentially, HHV‐6‐associated disease could be addressed by active or passive immunotherapy that reconstitutes virus‐specific CD8+ T‐cell responses.