bluuebunny/crossref_metadata_2025 huggingface dataset:
Coke Formation during the Methanol‐to‐Olefin Conversion: In Situ Microspectroscopy on Individual H‐ZSM‐5 Crystals with Different Brønsted Acidity
Authors: Mores Davide , Kornatowski Jan , Olsbye Unni , Weckhuysen Bert M.
Published: February 2011

Coke formation during the methanol‐to‐olefin (MTO) conversion has been studied at the single‐particle level with in situ UV/Vis and confocal fluorescence microscopy. For this purpose, large H‐ZSM‐5 crystals differing in their Si/Al molar ratio have been investigated. During MTO, performed at 623 and 773 K, three major UV/Vis bands assigned to different carbonaceous deposits and their precursors are observed. The absorption at 420 nm, assigned to methyl‐substituted aromatic compounds, initiates the buildup of the optically active coke species. With time‐on‐stream, these carbonaceous compounds expand in size, resulting in the gradual development of a second absorption band at around 500 nm. An additional broad absorption band in the 600 nm region indicates the enhanced formation of extended carbonaceous compounds that form as the reaction temperature is raised. Overall, the rate of coke formation decreases with decreasing aluminum content. Analysis of the reaction kinetics indicates that an increased Brønsted acid site density facilitates the formation of larger coke species and enhances their formation rate. The use of multiple excitation wavelengths in confocal fluorescence microscopy enables the localization of coke compounds with different molecular dimensions in an individual H‐ZSM‐5 crystal. It demonstrates that small coke species evenly spread throughout the entire H‐ZSM‐5 crystal, whereas extended coke deposits primarily form near the crystal edges and surfaces. Polarization‐dependent UV/Vis spectroscopy measurements illustrate that extended coke species are predominantly formed in the straight channels of H‐ZSM‐5. In addition, at higher temperatures, fast deactivation leads to the formation of large aromatic compounds within channel intersections and at the external zeolite surface, where the lack of spatial restrictions allows the formation of graphite‐like coke.
Enlightened Enzymes: Strategies to Create Novel Photoresponsive Proteins
Authors: Krauss Ulrich , Drepper Thomas , Jaeger Karl‐Erich
Published: February 2011

The photocontrol of protein functions, enzymatic reactions, and concomitantly biological activities in living cells and organisms represents a rapidly developing and interdisciplinary field of research at the interface of chemistry and biology. The nature of light allows for a non‐invasive gearing with unprecedented spatiotemporal resolution to exert control at the molecular and cellular level. This concept article aims to illustrate some of the classic as well as recently developed strategies employing protein‐engineering and chemical–biological hybrid methods to achieve photocontrol of biological processes. Recent cell biological examples will be highlighted and possible biotechnological applications will be presented.
LiB12PC, the First Boron‐Rich Metal Boride with Phosphorus—Synthesis, Crystal Structure, Hardness, Spectroscopic Investigations
Authors: Vojteer Natascha , Sagawe Vanessa , Stauffer Julia , Schroeder Melanie , Hillebrecht Harald
Published: February 2011

We present synthesis, crystal structure, hardness, and IR/Raman and UV/Vis spectra of a new compound with the mean composition LiB12PC. Transparent single crystals were synthesised from Ga, Li, B, red phosphorus and C at 1500 °C in boron nitride crucibles welded in Ta ampoules. Depending on the type of boron used for the synthesis we obtained colourless, brown and red single crystals with slightly different P/C ratios. Colourless LiB12PC crystallizes orthorhombic in the space group Imma (No. 74) with a=10.188(2) Å, b=5.7689(11) Å, c=8.127(2) Å and Z=4. Brown LiB12P0.89C1.11 is very similar, but with a lower P content. Red single crystals of LiB12P1.13C0.87 have a larger unit cell with a=10.4097(18) Å, b=5.9029(7) Å, c=8.2044(12) Å. EDX measurements confirm that the red crystals contain more phosphorus than the other ones. The crystal structure is characterized by a covalent network of B12 icosahedra connected by exohedral BB bonds and PP, PC or CC units. Li atoms are located in interstitials. The structure is closely related to MgB7, LiB13C2 and ScB13C. LiB12PC fulfils the electron counting rules of Wade and also Longuet‐Higgins. Measurements of Vickers micro‐hardness (HV=27 GPa) revealed that LiB12PC is a hard material. The optical band gaps obtained from UV/Vis spectra match the colours of the crystals. Furthermore we report on the IR and Raman spectra.
Material Efficiency and Sustainable Development in Chemistry: Where do we stand today?
Authors: Steinbach Adalbert , Winkenbach Rolf , Ehmsen Heiko
Published: February 2011

Der Klimawandel, die absehbare Verknappung der Rohstoffe und eine wachsende Weltbevölkerung, die die Nachfrage nach Energie und Rohstoffen – und damit auch deren Preise – noch weiter steigen lässt, stellen große Herausforderungen dar. Um diese bewältigen zu können, bedarf es umfassender Veränderungen in Politik, Wirtschaft und Gesellschaft im Sinne des Leitprinzips der Nachhaltigkeit (Sustainable Development). Die nationale Nachhaltigkeitsstrategie 2002 der Bundesregierung gibt konkrete Ziele vor, so z. B. auch für die Reduzierung des Rohstoffverbrauchs. Ziel ist eine Verdoppelung der (materialwirtschaftlichen) Produktivität (Materialeffizienz) von 1994 bis 2020. Ihre systematische Steigerung setzt voraus, dass sie gemessen und als Key Performance Indicator (KPI) zum Steuern der Entwicklung und Verbesserung industrieller Prozesse verwendet wird. Dies gilt namentlich für die hier betrachteten Stoffumwandlungsprozesse der Chemiebranche.
Regeneration of working solution in the hydrogen peroxide production process
Authors: Shang Hui , Zhou Hongjun , Zhang Wenhui , Zhang Kunlin
Published: February 2011

The regeneration of working solutions is an important procedure during the anthraquinone process for hydrogen peroxide production, which commonly uses activated alumina for this purpose. This study investigated the impact of different factors on regeneration performance using a fixed bed reactor and found that temperature, contact time, and the catalyst's active component were the key factors. Catalysts with higher alkali content improve regeneration performance. The catalysts' binders and the post‐treatment method affect their physical strength, but steam counteracts this due to the reaction of the active component with water.
Kinetic studies on vapour phase pyridine synthesis and catalyst regeneration studies
Authors: Suresh Kumar Reddy Kuppireddy , Sreedhar Inkollu , Vijaya Raghavan Kondapuram
Published: February 2011

The kinetics of vapour phase aminocylisation of acetaldehyde, formaldehyde, and ammonia over deactivating HZSM‐5 catalyst is studied. A series‐parallel reaction scheme has been employed in which coke formation from its precursors has been lumped. Applying the concept of separable kinetics, the catalyst deactivation and reaction kinetics unconstrained and constrained by it are studied independently. Employing experimental time on stream studies, the rate of catalyst decay has been computed from the latter. A catalyst deactivation function based on experimental decay of its activity has been evaluated separately. Its magnitude and trajectory matched well with that of the computed catalyst decay function. It facilitated to obtain a direct relationship between coke formation and product distribution as a function of time on stream for aminocyclisation. An attempt has also been made to study the regeneration characteristics of the catalyst.
Synthesis of smart hydrogels by radiation polymerisation for use as slow drug delivery devices
Authors: Singh Baljit , Sharma Vikrant , Kumar Sanjay
Published: February 2011

This article deals with the modification of medicinally important psyllium polysaccharide with acrylamide through radiation crosslinked polymerisation for the design of double potential hydrogels meant for slow release of insulin. Here the double potential is due to the inherent blood sugar lowering ability of psyllium and release of insulin in controlled manner from the drug loaded hydrogels. Synthesis of hydrogels and their characterisation by scanning electron micrography (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and swelling studies have been discussed. The release dynamics of model drug insulin from the hydrogels has been studied for the evaluation of the release mechanism. The release of the drug from the hydrogels occurred through non‐Fickian diffusion mechanism.
Effect of geometric variations on the performance of gas dispersion impellers with semicircular blades
Authors: Fasano Julian B. , Myers Kevin J. , Janz Eric E.
Published: February 2011

The effects of impeller blade width and blade number on the gas dispersion behaviour of disc impellers with semicircular blades have been characterised. Increasing blade width or number increases the ungassed turbulent power number and reduces the drop in power draw upon gassing. While speed and power required for gas dispersion decrease with increasing blade width and number, the dispersion torque is relatively independent of these impeller geometric characteristics. A three‐blade impeller exhibits the worst gas dispersion characteristics, while a four‐blade impeller with non‐uniform blade spacing outperforms a four‐blade impeller with uniform blade spacing.
Biosorption of lead(II) from aqueous solution on glutaraldehyde cross‐linked chitosan beads
Authors: Suguna M. , Siva Kumar N. , Subba Reddy A. , Boddu V. M. , Krishnaiah A.
Published: February 2011

The ability of glutaraldehyde cross‐linked chitosan beads (GCC beads) as synthetic adsorbent for adsorptive removal of Pb(II) ions from aqueous solutions is investigated in the present study. The biosorbent has been characterised by Brunner, Emmett, and Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. Equilibrium and column flow adsorption characteristics of Pb(II) ions on the biosorbent were studied. The effects of experimental variable parameters such as pH, concentration of metal ion, amount of adsorbent, contact time, temperature and interfering ions on adsorption have been investigated. The equilibrium data are fitted to pseudo‐first order, pseudo‐second order, fractionary order, chemisorption, Weber–Morris and Boyd models. Based on R2 and error function values, it is observed that the kinetic data are better fitted to pseudo‐second‐order kinetic model and chemisorption model. The experimental data are analysed using Langmuir, Freundlich, and Sips adsorption isotherm models. The monolayer adsorption capacity of GCC beads as obtained from Langmuir isotherm at 35°C is found to be 204.0 mg/g. The thermodynamic constants of the adsorption process: ΔH0, ΔS0 and ΔG0 are evaluated. The results show that biosorption of Pb(II) ions on GCC beads are endothermic and spontaneous.
Decreasing the peroxide decomposition in the magnesia slurry
Authors: Wekesa Moses , Ni Yonghao
Published: February 2011

The peroxide bleaching process for mechanical pulps using weak alkali sources such as magnesium hydroxide (Mg(OH)2), received much attention recently. The magnesia slurry (containing 61.2% Mg(OH)2) can be used for this purpose. In this paper, we studied the manganese‐induced peroxide decomposition in commercial magnesium hydroxide slurry (magnesia). The results showed that peroxide decomposition occurs under the conditions of magnesia based bleaching process. This is due to impurities, particularly manganese in the magnesia slurry. Similar to the conventional sodium hydroxide based process, sodium silicate can effectively decrease the manganese‐induced peroxide decomposition. However, the amount of silicate required is significantly less. It was found that diethylenetriaminepentaacetic acid (DTPA) or its sodium salt, can also be an effective stabiliser in the system. The chemistry of the manganese‐induced peroxide decomposition was discussed.
Experimental investigation of column efficiency for two ternary systems in a three‐phase packed distillation column
Authors: Torkmahalleh M. Amouei , Rahmati M.M. Montazer , Haghi B. Nematdoost
Published: February 2011

In this work, the effect of vapor load and initial feed concentrations on column efficiency and liquid hold‐up in a two‐ and three‐phase packed distillation column at total reflux was investigated. Results for the two investigated mixtures (n‐heptane, n‐hexane, water) and (ethyl acetate, 1‐butanol, water) reveal that column efficiency remains almost constant for the former mixture but changes significantly for the latter. Specific liquid hold‐up and water to organic‐phase volumetric ratio within the column affect the column efficiency due to variations in initial feed concentrations. Influence of vapor load on separation efficiency and specific liquid hold‐up is also studied.
Comparison of mixing index for binary and ternary mixtures of irregular particles in a gas–solid fluidized bed
Authors: Sahoo A. , Garg R. K. , Roy G.K.
Published: February 2011

Ternary mixtures of equi‐density particles have been fluidized in a gas–solid fluidized bed to study the mixing characteristics. A correlation for the mixing index has been developed for these mixtures. The mixing index for the ternary mixtures has also been calculated by the already available method. Finally a comparison has been made for the values of the mixing index calculated by both the methods against the experimental ones. The values of the mixing index for the ternary mixtures thus obtained have also been compared with those of the binary mixtures thereby indicating its application for real life multi‐component mixing over a wide range of parameters.
Process energy efficiency in pervaporative and vacuum membrane distillation separation of 2,3‐butanediol
Authors: Shao Pinghai , Kumar Ashwani
Published: February 2011

This work focused on the energy aspects of the pervaporative separation of 1‐butanol/2,3‐butanediol. A numeric model was developed to simulate the mass and energy balance of the pervaporation process. It was found that the distribution of evaporation heat requirement over the membrane area is asymmetric, and more than 85% of the heat was consumed in the 60% of the membrane area. It was also revealed that recycling the permeate having higher than 5% w/w 2,3‐butanediol can improve the recovery of 2,3‐butanediol, and thus enhance the process energy efficiency. Two recycling strategies (the single or multiple point admission of permeate to the retentate flow) were explored. The specific energy requirement (the heat required by generating 1 kg 99.5% w/w 2,3‐butanediol as product) was proposed to evaluate the process energy efficiency of both the pervaporation and vacuum membrane distillation, and it was shown that pervaporation can bring about nearly four times energy savings over the vacuum membrane distillation.
Near wall effects in the plug flow of pulp suspensions
Authors: Fock Helena , Claesson Julia , Rasmuson Anders , Wikström Tomas
Published: February 2011

Experimental data by the authors are further analysed to gain a more detailed understanding of the mechanisms of the plug flow and near‐wall behaviour in the pipe flow of pulp suspensions at concentrations up to 4.7% by weight. The results indicate two‐phase flow effects near the wall, one being that the apparent viscosity is higher than that of water. Another is that the wall shear stress estimated with the pressure drop data and a force balance is much higher than the one obtained with the measured velocity profile, indicating the presence of mechanical friction forces.
Mathematical analysis of effects on the electrostatic double layer of nanoscale surfaces in microfluidic channels
Authors: Aston D. E. , Berven C. A. , Williams B. C. , Basu A.
Published: February 2011

The effects of microfluidics on the electrostatic double layer (EDL) of a nano‐structured electrode are investigated through numerical modelling. The parameters of interest are the height and spacing of nanostructures, specifically, nanowire and “nanopillar” pairs rising from an idealised sensor substrate perpendicular to the fluid flow. A direct comparison of the EDL thicknesses at the peaks and valleys of this nanostructure are reported for variations in fluid velocity, nanowire spacing, and height under fixed conditions of combined pressure‐driven and electro‐osmotic driving forces. In a microchannel based on the Navier–Stokes and Helmholtz–Smoluchoswki flow models, numerical simulations provide insight into the practical design of chemically selective nanomaterial electrodes for potentiometric detection of ions in water.
CFD simulation of free liquid surface motion in a pilot plant stirred tank
Authors: Jahoda M. , Moštěk M. , Fořt I. , Hasal P.
Published: February 2011

The Volume of Fluid method together with the Large Eddy Simulation technique for turbulence flow was used for CFD prediction of liquid flow and free liquid surface motion in a pilot plant cylindrical flat‐bottomed stirred tank with an inner diameter of 1 m filled with tap water at room temperature. A pitched‐blade (45°) down pumping impeller (diameter of 0.33 m) with six blades was used for stirring. The impeller speed was 180 rpm. For simulation of the impeller motion, the sliding mesh method was adopted. The CFD simulations of the flow field predicted a highly complex, multi‐dimensional dynamic system exhibiting unstable, pseudo‐stationary behaviour. The main advantage of this CFD simulation is the prediction of the velocity flow patterns and the free surface elevation/depression in the whole system at one time. The results for the location and dimensions of the free liquid surface fluctuation correspond well with an experimental investigation by a conductivity method.
Theoritical analysis and simulation of five‐zone simulating moving bed for ternary mixture separation
Authors: Khan H. , Younas M.
Published: February 2011

In the present work a mathematical model has been presented to study the behaviour of five‐zone simulating moving bed (SMB) system for the separation of a ternary mixture of certain amino acids. These are methionine, phenylalanine and tryptophan, possessing linear isotherms values. Safety margin method has been used to design the SMB system while triangle theory became the basis to calculate the operating conditions at fixed feed flow rate. It was found that for same safety factor (β) value in each zone, increase in β value causes the purity values of all product streams to increase up to a definite value. Further increase in β value shows the effect of decrease in separation efficiency, because of dominance of axial dispersion and mass transfer resistances. The effect of zone safety factor (zone flow rate βII, βIII and βIV) values on the separation performance of five‐zone SMB have also been investigated which remained an important issue in SMB current research. Increase in βII value results in rising tryptophan purity, phenylalanine purity improves due to increase in βIII value and increase in βIV value becomes the basis for enhancing methionine purity. In column profile study, the solute concentration profile diminishes due to increase in particular separation zone safety factor value. This happened due to low column switching time with high desorbent flow rate to the system. The developed mode was run in Aspen Chromatography vis 12.1. (2004) simulator for simulation studies.
Synthesis of Amino‐Functionalized Hexagonal Mesoporous Silica for Adsorption of Pb2+
Authors: Wei Kun , Shu Lijun , Guo Wusheng , Wu Yuan , Zeng Xiaofeng
Published: February 2011

Highly ordered amino‐functionalized hexagonal mesoporous silica (HMS‐NH2) had been synthesized successfully by co‐condensation. The resultant materials were characterized by means of XRD, TEM, FT‐IR, N2 ad‐desorption and 29Si NMR to confirm the ordered mesoporous structure and the functionalization of the amino groups. The sample was employed as a Pb2+ adsorbent in aqueous solutions at room temperature. Both Lagergren's first order kinetic model and Lagergren's second order kinetic model were used to describe the adsorption data. It was found that the pseudo second order model fitted the sorption kinetic data better than the pseudo first order model. According to the information analyzed from AAS, HMS‐NH2 had a Pb2+ adsorption amount of over 90.7 mg·g−1, showing a promising application for the treatment of wastewater containing Pb2+ ions.
Ultrasonic Extraction Coupled with Capillary Electrophoresis for the Determination of Azo Dyes in Lipsticks Using Ionic Liquid as Dynamic Coating and Background Electrolyte
Authors: Li Dan , Wang Ziming , Wang Lu , Xu Xu , Zhang Hanqi
Published: February 2011

A simple and rapid method based on ultrasonic extraction and capillary electrophoresis using 1‐butyl‐3‐methylimidazolium tetrafluoroborate as dynamic coating and background electrolyte was developed. The method was applied to the separation and determination of three azo dyes in two lipsticks. To increase extraction rate and yield, lipstick samples were coated on a glass slide before ultrasonic extraction. The dyes were extracted by ultrasonic extraction for 30 min, and then determined by capillary electrophoresis. Several experimental factors, such as ionic liquid concentration, pH value of background electrolyte and applied voltage, were examined and optimized. Under the optimal conditions, three azo dyes were completely separated within 12 min, and the detection limits for the three azo dyes ranged from 0.33 to 0.88 μg/mL. The recoveries were in the range of 96.8% to 108.8%.
Proteomics Analysis of T Lymphocytes Damage Induced by Ionizing Irradiation
Authors: Shi Ying , Zhang Xuan , Liu Ning , Liang Feng , Song Fengrui , Liu Zhiqiang , Liu Shuying
Published: February 2011

Human T lymphocytes were found to be highly radiosensitive and complex cellular responses including apoptosis could be induced upon exposure to X‐ray irradiation. However, the mechanism of apoptosis associated with irradiation was not clear. In this study, a proteomic method was applied to investigation on alteration of proteome of human T‐lymphocyte cells after irradiation. The Jurkat cells were irradiated with 4 Gy X‐ray and the cell lysates were collected at different times after irradiation (6, 12, 18, 24 and 48 h). The whole proteins were separated and quantified by two‐dimensional fluorescence difference gel electrophoresis, and then the differentially expressed proteins were identified by mass spectrometry. 4 proteins exhibited significant irradiation‐induced difference in abundance, including L‐plastin, bifunctional purine biosynthesis protein, tubulin beta chain, beta‐actin. Differentially expressed proteins were reported to be directly or indirectly involved in the function of human T lymphocyte. Thus, this study might provide clues to identify proteins with biological significance related to irradiation.
Syntheses, Structures and Properties of Four Manganese Coordination Polymers Derived from 4‐Amino‐3,5‐bis(imidazol‐1‐ylmethyl)‐1,2,4‐triazole
Authors: Feng Yunfei , Yuan Deyun , Wang Ju , Li Baolong , Li Haiyan
Published: February 2011

The reaction of 4‐amino‐3,5‐bis(imidazol‐1‐ylmethyl)‐1,2,4‐triazole (abit) and manganese(II) salts yields four coordination polymers {[Mn(abit)3](ClO4)2}n (1), {[Mn(abit)3](PF6)2}n (2), [Mn(abit)(dca)2(H2O)2]n (3a) and [Mn(abit)(dca)2(H2O)2]n (3b). Compounds 1 and 2 are one‐dimensional triple‐stranded chain. Compounds 3a and 3b are polymorphous and construct one‐dimensional single chain. The conformational analysis is performed. The thermal properties have been investigated.
Facile Synthesis of Multi‐Branched Gold Nanostructures through a TBAB‐Assisted Route in Aqueous Solution and Their SERS Property
Authors: Wang Luyan , Wu Xinzhou , Pei Meishan , Wu Zhiyan , Li Xiaonan , Tao Xutang
Published: February 2011

Facile synthesis of multi‐branched gold nanostructures by using the tetrabutyl ammonium bromide (TBAB) as a capping agent is described. The reaction is carried out in a one‐step process at mild temperature. Gold nanostructures with more than six sharp branches ranging from 70 to 130 nm in length are synthesized in high yield. It is proposed that the relative weak adsorption capacity of TBAB leads to the incompletely covered gold surface and the growth of nanoparticles occurs on the uncovered gold surface, and therefore short branches appear consequently. Then positively charged TBAB layers on the gold surfaces prevent the branches from aggregating with each other which stimulates the branch growth. The prepared branched gold nanoparticles show efficient surface‐enhanced Raman scattering (SERS) properties. Low temperature (4°C) is unfavorable to the formation of multi‐branched gold nanostructures, and only thin small irregular plate‐like nanoparticles are produced. The addition of SDS in TBAB aqueous solution results in forming SDS micelles at much lower concentration of SDS (0.4 mmol/L) as compared to that in pure water, and short branched gold nanoparticles are obtained in the SDS‐TBAB system.
Controlled‐growth of Zn(OH)F Microbesoms in the Mild Aqueous Solution and Their Photocatalytic Activity
Authors: Peng Ying
Published: February 2011

Zn(OH)F microbesoms have been synthesized on a large scale by a facile solution‐based method using polymer as crystal growth modifier. The obtained products were characterized by X‐ray powder diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The effects of modifier polyacrylamide (PAM), reaction time, concentrations of NaF on the morphology and size of the product were studied. The results revealed that the Zn(OH)F microbesom had orthorhombic structures. Experimental conditions had all influence on the shape and size of the final products, but polymer PAM played the key role in formation of the Zn(OH)F microbesom. This novel structures exhibited good UV photocatalytic abilities.
Asymmetric Direct Aldol Reaction of Cyclohexanone Catalyzed by (N′‐Benzyl‐N′‐D‐prolyl)‐trans‐4‐hydroxy‐L‐proline Hydrazide
Authors: Cheng Chuanling , Wang Wenliang
Published: February 2011

A new proline catalyst, namely (N′‐benzyl‐N′‐D‐prolyl)‐trans‐4‐hydroxy‐L‐proline hydrazide, has been prepared and proved to be a superior catalyst for the asymmetric aldol reaction of cyclohexanone and aromatic aldehydes, affording up to 98:2 dr and 98% ee.
Carbon‐Based Solid Acid as An Efficient and Reusable Catalyst for One‐Pot Synthesis of Tetrasubstituted Imidazoles under Solvent‐Free Conditions
Authors: Tavakoli‐Hoseini Niloofar , Davoodnia Abolghasem
Published: February 2011

Carbon‐based solid acid catalyst was found to be highly efficient, eco‐friendly and recyclable heterogeneous catalyst for the multicomponent reaction of benzil, aromatic aldehyde, primary amine and ammonium acetate, giving rise to 1,2,4,5‐tetrasubstituted imidazoles in good to excellent yields. The present methodology offers several advantages, such as high yields, short reaction time, mild reaction condition and a recyclable catalyst with a very easy work up.
Preparation of CuS‐P(NIPAM‐co‐MAA) Hybrid Microgels with Controlled Surface Structures
Authors: Zhang Ying , Liu Huijin , Fang Yu
Published: February 2011

Copper sulfide‐poly(isopropylacrylamide‐co‐methacrylic acid) [CuS‐P(NIPAM‐co‐MAA)] hybrid microgels with patterned surface structures have been synthesized by means of the polymer microgel template technique. The results showed that the surface morphology of the hybrid microgels could be regulated by controlling the decomposition of thioacetamide (TAA) in an acidic medium. The rate of precipitation and the amount of metal sulfide significantly affect the surface structures of the hybrid microgels.
Investigating the Calculation of Rotational Viscosity of the Mixture Comprising Different Kinds of Liquid Crystals: Molecular Dynamics Computer Simulation Approach
Authors: Kim Jinsoo , Jamil Muhammad , Jung Jae Eun , Jang Jae Eun , Farzana Ahmad , Jin Woo Lee , Sang Woo Park , Woo Min‐Kyung , Kwak Ji Yeon , Jeon Young‐Jae
Published: February 2011

Molecular dynamics (MD) computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display (LCD) community, usually are employed for computing the equilibrium and transport properties of a classical many body system, since they are very similar to real experiments in many respects. In this paper we present molecular dynamics computer simulation results taken for a mixture of the two different kinds of nematic liquid crystals (LCs). We calculated rotational viscosity from Brownian behavior with friction of the mean director of the mixture comprising pentylcyanobiphenol (5CB) and decylcyanobiphenol (10CB) by using molecular dynamics computer simulation, where intermolecular potential parameter is Generalized AMBER force field (GAFF). Our computed results show a good agreement with the experimental results.
Diperoxo Complexes of Vanadium(V) Containing Mannich Base Ligands
Authors: Mahajan Simpy , Singh Balgar , Sharma Mohita , Sheikh H. N. , Kalsotra B. L.
Published: February 2011

The vanadium(V) peroxo complexes containing Mannich base ligands having composition Na[VO(O2)2(L‐L)]·H2O [where L‐L=morpholinobenzyl acetamide (MBA), piperidinobenzyl acetamide (PBA), morpholinobenzyl benzamide (MBB), piperidinobenzyl benzamide (PBB), morpholinomethyl benzamide (MMB), piperidinomethyl benzamide (PMB), morpholinobenzyl formamide (MBF), piperdinobenzyl formamide (PBF)] have been reported. The complexes have been prepared by stirring vanadium pentoxide with excess of 30% aqueous‐H2O2 followed by treatment with ethanolic solution of the ligand and finally maintained the pH of the reaction mixture by adding dilute solution of sodium hydroxide. The synthesized complexes have been characterized by various physico‐chemical techniques, via elemental analysis, molar conductivity, magnetic susceptibility measurements, infra red, electronic, mass, 1H NMR spectral and TGA/DTA studies. These studies revealed that the synthesized complexes are uni‐univalent electrolytes and diamagnetic in nature. The ligands are bound to metal in a bidentate mode through carbonyl oxygen and the ring nitrogen. Thermal analysis result provides conclusive evidence for the presence of one molecule of lattice water in the complexes. Mass spectra confirm the molecular mass of the complexes.
Pyridine‐N‐oxide: An Efficient Organocatalyst for Ring‐Opening Reactions of Aziridines with Aryl Thiols
Authors: Yang Qin , Yin Zhenlan , Yang Min , Peng Yiyuan
Published: February 2011

Pyridine‐N‐oxide serves as an efficient catalyst for the ring‐opening reactions of N‐tosylaziridines with various aryl thiols under mild conditions. This transformation is highly effective, which gives rise to the corresponding β‐amino sulfides in good to excellent yields.
Improving FRET‐Based Monitoring of Single Chemomechanical Rotary Motors at Work
Authors: Börsch Michael , Wrachtrup Jörg
Published: February 2011

Protein dynamics are observable in real time using internal distance measurements of reference positions. Based on Förster resonance energy transfer (FRET) as the distance ruler between two fluorescent markers, investigations of single molecules one at a time have modified our views of protein conformational changes. X‐ray crystallography provides trapped conformations at atomic resolution and NMR can add information about flexible parts of proteins, but the pathways between these structures including unknown conformations are often not directly accessible. Especially for membrane enzymes comprising multiple subunits, limited structural information requires alternative experimental methods to follow conformational pathways. Herein we summarize the knowledge gathered from single‐molecule FRET studies of the membrane‐embedded rotary nanomotor FoF1‐ATP synthase. In addition, new ideas and concepts to shift and extend the current limitations of the confocal FRET detection approach using freely diffusing, liposome‐reconstituted, individual enzymes are discussed: nanodiamonds as new fluorophores, optimized laser excitation schemes, Hidden Markov Models for software‐based FRET trajectory analysis, and application of the anti‐Brownian electrokinetic trap (ABELtrap) to keep the single enzyme in focus.
FRET and FCS—Friends or Foes?
Authors: Sahoo Harekrushna , Schwille Petra
Published: February 2011

Fluorescence correlation spectroscopy (FCS) and Förster resonance energy transfer (FRET) are both scientific concepts that are frequently discussed in the context of single‐molecule fluorescence techniques. In contrast to FCS, FRET is strictly not a technique but a photophysical phenomenon, which can be employed in combination with any method that probes fluorescence intensity or lifetime. Thus, the combination of FCS with FRET is possible and—although these concepts are quite often treated as alternative approaches, particularly for the analysis of biological systems—also quite attractive. However, under certain circumstances, for example, for applications of fluorescence cross‐correlation spectroscopy, FRET effects can cause significant complications for quantitative data analysis, and careful calibration has to be carried out to avoid FRET‐induced artifacts. This can be most elegantly done if alternating excitation schemes such as PIE (pulsed interleaved excitation) are employed. In this minireview, we discuss the potential and the caveats of FCS combined with FRET and give a short record on successful and promising applications.
Single‐Molecule FRET Ruler Based on Rigid DNA Origami Blocks
Authors: Stein Ingo H. , Schüller Verena , Böhm Philip , Tinnefeld Philip , Liedl Tim
Published: February 2011

Fluorescence resonance energy transfer (FRET) has become a work‐horse for distance measurements on the nanometer scale and between single molecules. Recent model systems for the FRET distance dependence such as polyprolines and dsDNA suffered from limited persistence lengths and sample heterogeneity. We designed a series of rigid DNA origami blocks where each block is labeled with one donor and one acceptor at distances ranging between 2.5 and 14 nm. Since all dyes are attached in one plane to the top surface of the origami block, static effects of linker lengths cancel out in contrast to commonly used dsDNA. We used single‐molecule spectroscopy to compare the origami‐based ruler to dsDNA and found that the origami blocks directly yield the expected distance dependence of energy transfer since the influence of the linkers on the donor–acceptor distance is significantly reduced. Based on a simple geometric model for the inter‐dye distances on the origami block, the Förster radius R0 could directly be determined from the distance dependence of energy transfer yielding R0=5.3±0.3 nm for the Cy3–Cy5 pair.
A Mixed Quantum–Classical Description of Excitation Energy Transfer in Supramolecular Complexes: Förster Theory and beyond
Authors: Megow Jörg , Röder Beate , Kulesza Alexander , Bonačić‐Koutecký Vlasta , May Volkhard
Published: February 2011

Electronic excitation energy transfer (EET) is described theoretically for the chromophore complex P4 formed by a butanediamine dendrimer to which four pheophorbide‐a molecules are covalently linked. To achieve a description with atomic resolution, and to account for the effect of an ethanol solvent, a mixed quantum–classical methodology is utilized. Room‐temperature molecular dynamics simulations are used to describe the nuclear dynamics, and EET is accounted for in utilizing a mixed quantum–classical formulation of the transition rates. Therefore, the full quantum expression of the EET rates is given and the change to a mixed quantum–classical version is briefly explained. The description results in the calculation of transition rates which coincide rather satisfactory with available experimental data on P4. It is also shown that different assumptions of classical Förster theory are not valid for P4. The temporal behavior of EET deduced from the rate equations is confronted with that following from the solution of the time‐dependent Schrödinger equation entering the mixed quantum–classical description of EET. From this we can conclude that EET in flexible chromophore complexes such as P4 can be rather satisfactory estimated by single transition rates. A correct description, however, is only achievable by using a sufficiently large set of rates that correspond to the various possible equilibrium configurations of the complex.
Chiral Reconstruction of a Metal Surface by Adsorption of Racemic Malic Acid
Authors: Roth Christian , Parschau Manfred , Ernst Karl‐Heinz
Published: February 2011

The adsorption of racemic malic acid on Cu(110) has been studied in ultrahigh vacuum (UHV) by means of scanning tunneling microscopy (STM), low‐energy electron diffraction (LEED), X‐ray photoelectron spectroscopy (XPS) and reflection–absorption infrared spectroscopy (RAIRS). In contrast to enantiopure malic acid, which forms eleven different ordered phases on Cu(110), only four structures are observed for the racemate. Three of them are superpositions of enantiomorphous phases that have not been observed for the pure enantiomers. Only the non‐enantiomorphous c(2×4) saturation structure was found for pure enantiomers and for the racemate, but also shows differences at short‐range order. This suggests that heterochiral two‐dimensional (2D) phases are present in all cases. A restructuring of the copper surface is clearly identified in STM for some phases after careful annealing, causing chirality transfer via the metal substrate.
A high throughput, interactive imaging, bright‐field wound healing assay
Authors: Zordan Michael D. , Mill Christopher P. , Riese David J. , Leary James F.
Published: February 2011

The wound healing assay is a commonly used technique to measure cell motility and migration. Traditional methods of performing the wound healing assay suffer from low throughput and a lack of quantitative data analysis. We have developed a new method to perform a high‐throughput wound healing assay that produces quantitative data using the LEAP™ instrument. The LEAP™ instrument is used to create reproducible wounds in each well of a 96‐well plate by laser ablation. The LEAP™ then records bright field images of each well at several time points. A custom texture segmentation algorithm is used to determine the wound area of each well at each time point. This texture segmentation analysis can provide faster and more accurate image analysis than traditional methods. Experimental results show that reproducible wounds are created by laser ablation with a wound area that varies by less than 10%. This method was tested by confirming that neuregulin‐2β increases the rate of wound healing by MCF7 cells in a dose dependent manner. This automated wound healing assay has greatly improved the speed and accuracy, making it a suitable high‐throughput method for drug screening. © 2011 International Society for Advancement of Cytometry
Microfilariae of Wuchereria bancrofti in urine: An uncommon finding
Authors: Verma Ritu , Vij Mukul
Published: February 2011

Filariasis is a global health problem commonly seen in tropics and subtropics. Microfilariae has been reported in cytological specimens from various sites but is an unusual finding from sediments of centrifuged normally voided urine samples. This highlights the presence of adult worms in the lymphatics and thus helping in prompt decision to start antihelminthic treatment besides providing surgical treatment for chyluria. Diagn. Cytopathol. 2011; © 2011 Wiley‐Liss, Inc.
Spectrum of orbital and ocular adnexal lesions: An analysis of 389 cases diagnosed by fine needle aspiration cytology
Authors: Gupta Nalini , Kaur Jasleen , Rajwanshi Arvind , Nijhawan Raje , Srinivasan Radhika , Dey Pranab , Singh Usha , Gupta Pankaj
Published: February 2011

The aim of the present study was to evaluate the scope and the limitations of fine needle aspiration cytology (FNAC) in orbital and ocular adnexal lesions. This study was a retrospective audit of 389 cases of orbital and ocular adnexal lesions subjected to FNAC over a period of 12 years (1998–2009). The cyto‐smears were reviewed and the lesions were categorized under different diagnostic categories in adult and pediatric population. Three hundred and one adult patients (age ≥15 years) and 88 pediatric patients (age ≤14 years) constituted the study group. In the adult population, there were 23.3% cases of infectious and lymphoproliferative lesions and 12.6% of benign cysts. In the pediatric population, 18.2% cases had infectious and lymphoproliferative lesions and 8% had benign cysts. Various benign tumors (9.6% in adults) included pleomorphic adenoma, meningioma, and schwannoma. Benign vascular tumors predominated in the pediatric population. A majority of malignant tumors in adults were lymphoreticular malignancies (12.6%); non‐Hodgkin's lymphoma being the most common followed by malignant epithelial tumors (10.3%). Nearly 3.6% cases of soft tissue/bone sarcomas and 6.3% of metastatic tumors were seen in adult population. However, most of the orbital tumors in the pediatric population were malignant small blue round cell tumors (33%). FNAC is a cost‐effective technique with good diagnostic value in the assessment of ophthalmic lesions, especially when sampling and interpretation are performed by experienced personnel in the light of clinico‐radiological information. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.
Assisting cytopathology training in medically under‐resourced countries: Defining the problems and establishing solutions
Authors: Field A. S. , Geddie W. , Zarka M. , Sayed S. , Kalebi A. , Wright C. A. , Banjo A. , Desai M. , Kaaya E.
Published: February 2011

Cytology is able to deliver rapid accurate diagnoses with minimal equipment and laboratory infrastructure at minimal cost, and this is especially so for fine needle biopsy (FNB), which is a powerful diagnostic tool in medically resource‐poor environments, where histopathology laboratories are small in number and poorly supported financially. The crucial element in the development of cytology services is to train a sufficient number of well trained cytopathologists and cytotechnologists to create a ‘critical mass’ of personnel who not only provide routine diagnostic services, but also can train an ever expanding number of pathologists, cytotechnologists, and health workers.

A review of practical programs to train cytopathologists and cytotechnologists in their own countries will be presented, including a recent series of FNB and cytology tutorials run in sub Saharan Africa. The need for local cytopathology programs and the potential for both local and visiting cytopathologists to provide a faculty will be discussed, as well as a range of possible programs which can bring African pathologists and trainee pathologists to Western institutions for periods of their training.

Ideally, the regional Societies of Cytology, including the recently formed West African Society of Cytology, will establish their own diagnostic protocols, training programs, syllabuses, examinations and accreditation and career pathways for both cytopathologists and cytotechnologists, and organize tutorials where they will invite overseas faculty to contribute.

Crucially, these new societies will empower cytopathologists and cytotechnologists to approach health services and governments to state the need for cytology services as a cost‐effective accurate diagnostic service that enhances patient care. Diagn.Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.
Reducing “atypical squamous cells” overdiagnosis on cervicovaginal smears by diligent cytology screening
Authors: Gupta Sanjay , Sodhani Pushpa
Published: February 2011

The frequency of possible reasons for “atypical squamous cells” (ASC) overdiagnosis on Papanicolaou (Pap) smears was analyzed. Pap smears of 199 women with negative biopsy outcome after an ASC diagnosis were reviewed. Special attention was paid to presence of reproductive tract infections (RTIs), perimenopausal cells (PM cells), immature metaplastic cells, hormone‐related alterations, and drying artefacts. Comparisons were made using χ2 test between the two ASC qualifiers and also between premenopausal and peri/postmenopausal women. Possible reasons for ASC overdiagnosis could be assigned on Pap smear review in 88/199 (44.2%) negative biopsies. Overall, PM cells were the most frequent reason for ASC overdiagnosis, being present in 35/199 (17.6%) smears. RTIs were the next most common cause (14.6%). PM cells were the most significant confounding factors for persistent ASC undetermined significance (ASC‐US) over interpretation (20.2%) while in none of the cases these were interpreted as ASC‐H (P = 0.004). Of these, 32 smears belonged to peri/postmenopausal women while only three to premenopausal women (P < 0.001). Immature metaplastic cells were significantly more frequent cause of ASC‐H rather than ASC‐US interpretation (P = 0.007). RTIs and drying artefacts were more frequently overcalled as ASC‐US (in premenopausal women) while hormonal changes were interpreted as ASC‐H. Hormone related changes, immature metaplastic cells and drying artefacts more commonly resulted in ASC interpretation in peri/ postmenopausal smears. The results of this study suggest that diligent screening can substantially reduce ASC overdiagnosis, thereby reducing the referrals/ follow ups. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.
Fine‐needle aspiration cytology of subcutaneous fat necrosis of the newborn: The cytology spectrum with review of the literature
Authors: Schubert Pawel T. , Razack Rubina , Vermaak Anine , Francois Jordaan H.
Published: February 2011

Subcutaneous fat necrosis of the newborn is a rare, transient panniculitis of full‐term infants. Diagnosis is usually made clinically; however, a biopsy is sometimes required. Fine‐needle aspiration biopsy (FNAB) offers an alternative to biopsy. The cytology shows a spectrum of changes ranging from clumped lobules of fat with opaque cytoplasm to necrotic aspirates with dispersed fat cells with opaque cytoplasm, foamy macrophages, multinucleated giant cells, lymphocytes, and neutrophils. Radially orientated, refractile, needle‐shaped crystals are visible in the cytoplasm of the fat cells and loose lying in the necrotic background. FNAB offers an alternative to biopsy with good results. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.