bluuebunny/crossref_metadata_2025 huggingface dataset:
Limitations of modern microeconomic theory of consumer choice: Sociological perspective
Authors: Radonjic Ognjen
Published: December 2008

Neoclassical theory of consumer choice needs to be reformed. Assumption that consumer choice is not influenced by the choice of others is in collision with reality. New and better theory of consumer choice is unimaginable without incorporation of intersubjective factors into the model of derivation of individual and aggregate (market) demand functions. Goal of this study is to underline widely neglected sociological factors that have significant influence on motivation and behavior of consumers. Inclusion of these factors into modern microeconomic theory is of essential importance if we are about to construct theoretical model aimed to describe reality in which we daily exist better than its predecessor did.
Experimental analysis of fuzzy controlled energy efficient demand controlled ventilation economizer cycle variable air volume air conditioning system
Authors: Rajagopalan Parameshwaran , Rajasekaran Karunakaran , Alagarsamy Senthilkumar , Iniyan S. , Lal Mohal
Published: December 2008

In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.
Flow boiling heat transfer coefficient of R-134a/R-290/R-600a mixture in a smooth horizontal tube
Authors: Balakrishnan Raja , Dhasan Lal , Rajagopal Saravanan
Published: December 2008

An investigation on in-tube flow boiling heat transfer of R-134a/R-290/R-600a (91%/4.068%/4.932% by mass) refrigerant mixture has been carried out in a varied heat flux condition using a tube-in-tube counter-flow test section. The boiling heat transfer coefficients at temperatures between -5 and 5?C for mass flow rates varying from 3 to 5 g/s were experimentally arrived. Acetone is used as hot fluid, which flows in the outer tube of diameter 28.57 mm, while the test fluid flows in the inner tube of diameter 9.52 mm. By regulating the acetone flow rate and its entry temperature, different heat flux conditions between 2 and 8 kW/m2 were maintained. The pressure of the refrigerant was maintained at 3.5, 4, and 5 bar. Flow pattern maps constructed for the considered operating conditions indicated that the flow was predominantly stratified and stratified wavy. The heat transfer coefficient was found to vary between 500 and 2200 W/m2K. The effect of nucleate boiling prevailing even at high vapor quality in a low mass and heat flux application is high-lighted. The comparison of experimental results with the familiar correlations showed that the correlations over predict the heat transfer coefficients of this mixture.
Thermodynamic simulation of ammonia-water absorption refrigeration system
Authors: Sathyabhama A. , Ashok Babu
Published: December 2008

The ammonia-water absorption refrigeration system is attracting increasing research interests, since the system can be powered by waste thermal energy, thus reducing demand on electricity supply. The development of this technology demands reliable and effective system simulations. In this work, a thermodynamic simulation of the cycle is carried out to investigate the effects of different operating variables on the performance of the cycle. A computer program in C language is written for the performance analysis of the cycle.
Conjugated heat transfer analysis of gas turbine vanes using MacCormack's technique
Authors: Kumar Micha , Alagumurthi N. , Palaniradja K.
Published: December 2008

It is well known that turbine engine efficiency can be improved by increasing the turbine inlet gas temperature. This causes an increase of heat load to the turbine components. Current inlet temperature level in advanced gas turbine is far above the melting point of the vane material. Therefore, along with high temperature material development, sophisticated cooling scheme must be developed for continuous safe operation of gas turbine with high performance. Gas turbine blades are cooled internally and externally. Internal cooling is achieved by passing the coolant through passages inside the blade and extracting the heat from outside of the blade. This paper focuses on turbine vanes internal cooling. The effect of arrangement of rib and parabolic fin turbulator in the internal cooling channel and numerical investigation of temperature distribution along the vane material has been presented. The formulations for the internal cooling for the turbine vane have been done and these formulated equations are solved by MacCormack's technique.
Geometric optimization of cross-flow heat exchanger based on dynamic controllability
Authors: Alotaibi Sorour , Alebrahim Asad
Published: December 2008

The operation of heat exchangers and other thermal equipments in the face of variable loads is usually controlled by manipulating inlet fluid temperatures or mass flow rates, where the controlled variable is usually one of the output temperatures. The aim of this work is to optimize the geometry of a tube with internal flow of water and an external cross-flow of air, based on its controllability characteristics. Controllability is a useful concept both from theoretical and practical perspective since it tells us if a particular output can be controlled by a particular input. This concept can also provide us with information about the easiest operating condition to control a particular output. A transient model of a tube in cross-flow is developed, where an implicit formulation is used for transient numerical solutions. The aspect ratio of the tube is optimized, subject to volume constraints, based on the optimum operation in terms of controllability. The reported optimized aspect ratio, water mass flow rate and controllability are studied for deferent external properties of the tube.
Heat transfer studies on spiral plate heat exchanger
Authors: Rajavel Rangasamy , Saravanan Kaliannagounder
Published: December 2008

In this paper, the heat transfer coefficients in a spiral plate heat exchanger are investigated. The test section consists of a plate of width 0.3150 m, thickness 0.001 m and mean hydraulic diameter of 0.01 m. The mass flow rate of hot water (hot fluid) is varying from 0.5 to 0.8 kg/s and the mass flow rate of cold water (cold fluid) varies from 0.4 to 0.7 kg/s. Experiments have been conducted by varying the mass flow rate, temperature, and pressure of cold fluid, keeping the mass flow rate of hot fluid constant. The effects of relevant parameters on spiral plate heat exchanger are investigated. The data obtained from the experimental study are compared with the theoretical data. Besides, a new correlation for the Nusselt number which can be used for practical applications is proposed.
Experimental study on the performance limitation of micro heat pipes of non circular cross-sections
Authors: Mahmood Lutful , Akhanda Razzaq
Published: December 2008

An experimental study of three different cross-sections (circular, semicircular and rectangular) of micro heat pipes having same hydraulic diameter (D= 3mm) is carried out at three different inclination angles (0?, 45?, 90?) using water as the working fluid. Evaporator section of the pipe is heated by an electric heater and the condenser section is cooled by water circulation in an annular space between the condenser section and the water jacket. Temperatures at different locations of the pipe are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the micro heat pipe is flattened. Thus among all cross-sections of the pipes circular cross-section exhibits the best thermal performance followed by semicircular and rectangular cross-sections. Moreover maximum heat transfer capability of the pipes also decreases with decreasing of its inclination angle. A correlation is developed using all the gathered data of the present study to predict the heat transfer coefficient of micro heat pipes of different cross-sections placed at different inclination angles.
Kelvin-Helmholtz discontinuity in two superposed viscous conducting fluids in a horizontal magnetic field
Authors: Khan Aiyub , Sharma Neha , Bhatia P.K.
Published: December 2008

The Kelvin-Helmholtz discontinuity in two superposed viscous conducting fluids has been investigated in the taking account of effects of surface tension, when the whole system is immersed in a uniform horizontal magnetic field. The streaming motion is assumed to be two-dimensional. The stability analysis has been carried out for two highly viscous fluid of uniform densities. The dispersion relation has been derived and solved numerically. It is found that the effect of viscosity, porosity and surface tension have stabilizing influence on the growth rate of the unstable mode, while streaming velocity has a destabilizing influence on the system.
Use of Standardized Outcome Measures in Physical Therapist Practice: Perceptions and Applications
Authors: Jette Diane U , Halbert James , Iverson Courtney , Miceli Erin , Shah Palak
Published: December 2008

Background

Standardized instruments for measuring patients' activity limitations and participation restrictions have been advocated for use by rehabilitation professionals for many years. The available literature provides few recent reports of the use of these measures by physical therapists in the United States.

Objective

The primary purpose of this study was to determine: (1) the extent of the use of standardized outcome measures and (2) perceptions regarding their benefits and barriers to their use. A secondary purpose was to examine factors associated with their use among physical therapists in clinical practice.

Design

The study used an observational design.

Methods

A survey questionnaire comprising items regarding the use and perceived benefits and barriers of standardized outcome measures was sent to 1,000 randomly selected members of the American Physical Therapy Association (APTA).

Results

Forty-eight percent of participants used standardized outcome measures. The majority of participants (>90%) who used such measures believed that they enhanced communication with patients and helped direct the plan of care. The most frequently reported reasons for not using such measures included length of time for patients to complete them, length of time for clinicians to analyze the data, and difficulty for patients in completing them independently. Use of standardized outcome measures was related to specialty certification status, practice setting, and the age of the majority of patients treated.

Limitations

The limitations included an unvalidated survey for data collection and a sample limited to APTA members.

Conclusions

Despite more than a decade of development and testing of standardized outcome measures appropriate for various conditions and practice settings, physical therapists have some distance to go in implementing their use routinely in most clinical settings. Based on the perceived barriers, alterations in practice management strategies and the instruments themselves may be necessary to increase their use.
Recovering the Early History of Canadian Criminology: Criminology at the University of British Columbia, 1951–1959
Authors: Parkinson Gary
Published: December 2008

This article is an account of the development of Canada's first criminology program, offered at the University of British Columbia from 1951 to 1959. The program included a B.A. in criminology with an honours option, an M.A. in criminology, and a postgraduate diploma. This program has been neglected in the history of criminology but deserves attention due to its innovative nature and to its impact on corrections in Canada. It emerged during the era when the new penology was being articulated and played a profound role both in transmitting this philosophy and in implementing it at the Haney Correctional Institution, which developed in concert with the university program. Elmer Kim Nelson, a criminologist from California, was in large part responsible for the shape and direction of both the university program and the prison. Although the program was short-lived, it exerted considerable influence on both the regional and the national scene for three decades.
W.B. Yeats's (Mis)Reading of Tagore: Interpreting an Alien Culture
Authors: Jelnikar Ana
Published: December 2008

The rise and fall of W.B. Yeats's enthusiasm for Rabindranath Tagore as a poet is analyzed here as due primarily to Yeats's own changing aspirations for restoring a pristine Ireland. Reinforcing this psychological interpretation is a post-colonial argument that finds Yeats, notwithstanding his opposition to colonial rule in Ireland and India, as unable to appreciate the Bengali poet as intellectually and politically a fully mature and autonomous individual. Once Tagore had rejected his British knighthood in protest against the Jallianwalla Bagh massacre, it is argued, he no longer fitted the benign but condescending stereotype of serene, spiritual Oriental that had helped propel him to the Nobel Prize.
Tagore's Conception of Cosmopolitanism: A Reconstruction
Authors: Tagore Saranindranath
Published: December 2008

This paper focuses on the nature of cosmopolitanism within the scope of Rabindranath Tagore's social and political thought, primarily by showing that the attacks on Martha Nussbaum's critique of patriotism and her attendant defence of cosmopolitanism miss the mark when directed against Tagore. It argues that Tagore's understanding of universality is not of an abstract Kantian sort, but assumes that particular cultural traditions can provide the bases for understanding and morally relating to others. Tagore's conception of rationality does not merely yield postmodern toleration of alterity, but aspires to dissolve instances of otherness altogether by enriching one's own tradition through hermeneutic absorption and assimilation.
Keys to the Kingdom: The Search for How Best to Understand and Perform the Songs of Tagore
Authors: Radice William
Published: December 2008

Searching for a way to understand the songs of Rabindranath Tagore that reflects their centrality in his creative work and goes deep, as it were, into his creative nervous system underlies this essay. Both the lyrics and the music of Tagore's songs [Rabindra-sangit] were composed by him and thus are intimately bound together. For appreciating the distinctive qualities of the songs a four-fold classification – based on characteristics of the four parts of a typical song in the Rabindra-sangit corpus – is proposed and sketched. There are also suggestions (and an appeal for higher performance standards) as to why, if he were alive today, Tagore might feel that his songs are being misinterpreted and misunderstood – but need not be in future.
Literary Assessments of Tagore by Bengali Muslim Writers
Authors: Qureshi Mahmud Shah
Published: December 2008

Though Rabindranath Tagore was not a Muslim, he was far from being a communally narrow Hindu and, though a Brahmin, was of the marginalized Pirali subcaste. Moreover, he was liberal and irenic in his ideas, and above all, culturally a Bengali. Thus it is not surprising that fellow Bengalis who were Muslim and themselves intimately concerned with the language, literature, and other aspects of Bengali culture would take a serious interest in Tagore. But the extent of that interest and the intellectual and emotional quality of the assessments of Tagore and his work by the many Bengali Muslim creative writers, intellectuals, and public figures surveyed here – including those who opted for India in 1947 and those who opted for East Pakistan and later Bangladesh – are impressive in their scope, diversity, and intensity.
Combined surgical and endovascular approach to treat symptomatic in-stent occlusion of the left common carotid artery origin
Authors: Shah Qaisar A. , Memon Muhammad Zeeshan , Tummala Ramachandra P. , Qureshi Adnan I.
Published: December 2008

Symptomatic occlusive lesions at the origins of the supra-aortic vessels pose challenges for treatment. Endovascular angioplasty and stent placement via the transfemoral approach is possible, but obtaining a stable position for the guide catheter via this approach is technically difficult. The authors describe the case of a 56-year-old man presenting with symptomatic occlusion of a previously placed stent at the origin of the left common carotid artery (CCA). An endovascular revascularization of the left CCA was planned. However, the absence of a lumen proximal to the stent prevented stable placement of a guide catheter via the transfemoral route. Consequently, the authors used a combined surgical and endovascular approach to gain access to the lesion. The left CCA was exposed surgically distal to the occlusion and clamped just proximal to its bifurcation to preserve flow from the external to the internal carotid artery (ICA) and to prevent embolism into the ICA. A wire was passed retrograde through the occlusive lesion and then was subsequently advanced proximally into the femoral sheath. This allowed transfemoral advancement of the appropriate endovascular devices to perform an angioplasty and placement of a stent. The patient remained neurologically stable, and postoperative studies showed improvement in cerebral perfusion. This case demonstrates the feasibility of distal-to-proximal stent delivery with a combined endovascular and surgical approach.
Radiographic analysis of trochlear notch sclerosis in the diagnosis of osteoarthritis secondary to medial coronoid disease
Authors: Carrera I. , Carmichael S. , Heller J. , Hammond G. , Draffan D.
Published: December 2008

Trochlear notch sclerosis (TNS) as assessed by radiography has been shown to be increased in elbow dysplasia (ED) associated medial coronoid process disease (MCD). The aims of this study were to investigate whether two defined radiographic tests evaluating TNS would increase the sensitivity of detecting osteoarthritis secondary to MCD, and to assess whether there was a correlation between increasing TNS with severity of MCD. Sixty-one dogs with MCD (121 elbows) were selected from the imaging database. The controls were nine cadavers (18 disease-free elbows). Standard International Elbow Working Group radiographs and CT scans were taken of each elbow. Plain radiographs were analysed using various assessments: osteophyte grade (0–3), coronoid grade (0–3), TNS descriptive grade (0–3) and TNS ratio. The TNS ratio was calculated from the depth of ulnar sclerosis at the level of the disto-cranial margin of the humeral condyles divided by the cranio-caudal ulna depth. The TNS descriptive assessment and ratio both increased the overall sensitivity of diagnosing osteoarthritis secondary to MCD above the other radiographic tests. The sensitivity of the TNS ratio at <0.3 mm was 91%-96% and the TNS descriptive assessment was 77%-96%. Radio-graphic TNS significantly increased with increasing severity of coronoid disease grade as evaluated by CT p<0.01. The finding that TNS increases the sensitivity of diagnosing osteoarthritis secondary to MCD is valuable to those that have neither a CT scanner nor arthroscopy readily available. The assessments described in this study are easy to apply and do not require any sophisticated technology in order to detect sclerosis.
Comparative study of vertebral fractures and luxations in dogs and cats
Authors: Lang J. , Jaggy A. , Spreng D. , Doherr M. G. , Forterre F. , Bali M. S.
Published: December 2008

The purpose of this retrospective study was to compare patterns of vertebral fractures and luxations in 42 cats and 47 dogs, and to evaluate the impact of species-related differences on clinical outcome. Data regarding aetiology, neurological status, radiographic appearance and follow-up were compared between the groups. The thoracolumbar (Th3-L3) area was the most commonly affected location in both cats (49%) and dogs (58%). No lesions were observed in the cervical vertebral segments in cats, and none of the cats showed any signs of a Schiff-Sherrington syndrome. Vertebral luxations were significantly more frequent in dogs (20%) than in cats (6%), whereas combined fracture-luxations occurred significantly more often in cats (65%) than in dogs (37%). Caudal vertebral segment displacement was mostly dorsal in cats and ventral in dogs, with a significant difference in direction between cats and large dogs. The clinical outcome did not differ significantly between the two populations, and was poor in most cases (cats: 61%; dogs: 56%). The degree of dislocation and axis deviation were both significantly associated with a worse outcome in dogs, but not in cats. Although several differences in vertebral fractures and luxation patterns exist between cats and dogs, these generally do not seem to affect outcome.
The role of psychosocial factors in young children's responses to cross‐examination style questioning
Authors: Zajac Rachel , Jury Emma , O'Neill Sarah
Published: December 2008

The goal of the present study was to ascertain whether individual differences in self‐esteem, self‐confidence, assertiveness and number of siblings could predict young children's responses to cross‐examination style questioning. Five‐ and 6‐year‐old children (N = 137) participated in a unique staged event and were then interviewed with analogues of direct and cross‐examination. Despite highly accurate direct examination reports, children made a large number of changes to these reports during cross‐examination, resulting in a significant decrease in accuracy. Poor cross‐examination performance was associated with low levels of teacher‐rated self‐confidence, self‐esteem and assertiveness, raising concern that the children who are likely to fare poorly during cross‐examination may be the very children who are most likely to appear as witnesses in the courtroom. Furthermore, number of siblings was inversely related to cross‐examination performance. Further research is required to pinpoint the specific mechanism(s) behind this finding. Copyright © 2008 John Wiley & Sons, Ltd.
Enhanced Light‐Harvesting and Photocatalytic Properties in Morph‐TiO2 from Green‐Leaf Biotemplates
Authors: Li Xufan , Fan Tongxiang , Zhou Han , Chow Suk‐Kwun , Zhang Wang , Zhang Di , Guo Qixin , Ogawa Hiroshi
Published: December 2008

The unique structure of green leaves endows them with an extremely high light‐harvesting efficiency. In this work, green leaves are applied as biotemplates to synthesize morph‐TiO2. The structural features favorable for light harvesting from the macro‐ to the nanoscale are replicated in morph‐TiO2 through a two‐step infiltration process and the N contained in the original leaves is self‐doped into the resulting samples. The absorbance intensities within the visible‐light range of morph‐TiO2 derived from different leaves increase by 103–258% and the band‐gap‐absorption onsets at the edge of the UV and visible‐light range show a red‐shift of 25–100 nm compared to those in TiO2 without the template. The photocatalytic activity of morph‐TiO2 is also improved, as proven by an electron paramagnetic resonance (EPR) study and degradation of rhodamine dye under irradiation with UV and visible light. The present work, as a new strategy, is of far‐reaching significance in learning from nature, driving us to make full use of the most‐abundant resources and structure‐introduced functions endowed by nature, opening up possibilities for extensive study of the physical and chemical properties of morph‐structured oxides and extending their potential for use in applications such as solar cells, photocatalysts, photoelectrical devices, and photoinduced sensors.
Two‐Dye Core/Shell Zeolite Nanoparticles: A New Tool for Ratiometric pH Measurements
Authors: Doussineau Tristan , Smaïhi Monique , Mohr Gerhard J.
Published: December 2008

The preparation of core/shell nanoparticles that enable ratiometric pH measurement is described. The core of the nanoparticles consists of a zeolite‐β matrix that exhibits a 3‐hydroxyflavone reference dye within the porous network. Coating an amorphous silica shell containing a fluorosensor around the zeolite through the Stöber process provides pH sensitivity to the nanoparticles. Morphological characterization (dynamic light scattering, transmission electronic microscopy) demonstrates the control of the sensing silica shell around the zeolite cores, leading to highly monodisperse spherical nanoparticles, while structural characterization (wide‐angle X‐ray diffraction, nitrogen adsorption) shows the amorphous character of the shell. Spectral characterization via UV/Vis absorption and steady‐state fluorescence shows good pH sensitivity of the resulting nanosensors with a pKa suitable for bioanalytical applications.
Near‐Infrared Mesoporous Silica Nanoparticles for Optical Imaging: Characterization and In Vivo Biodistribution
Authors: Lee Chia‐Hung , Cheng Shih‐Hsun , Wang Yu‐Jing , Chen Yu‐Ching , Chen Nai‐Tzu , Souris Jeffrey , Chen Chin‐Tu , Mou Chung‐Yuan , Yang Chung‐Shi , Lo Leu‐Wei
Published: December 2008

The characterization of near‐infrared (NIR) mesoporous silica nanoparticles (MSN) suitable for in vivo optical imaging with high efficiency is presented. Trimethylammonium groups modified MSN (MSN‐TA) with the average size of 50–100 nm was synthesized with incorporation of the TA groups into the framework of MSN. It was further adsorbed with indocyanine green (ICG) by electrostatic attraction to render MSN‐TA‐ICG as an efficient NIR contrast agent for in vivo optical imaging. The studies in stability of MSN‐TA‐ICG against pH indicated the bonding is stable over the range from acidic to physiological pH. The in vivo biodistribution of MSN‐TA‐ICG in anesthetized rat demonstrated a rather strong and stable fluorescence of MSN‐TA‐ICG that prominent in the organ of liver. Transmission electron microscopy (TEM) imaging and elemental analysis of silicon further manifested the physical and quantitative residences of MSN‐TA‐ICG in major organs. This is the first report of MSN functionalized with NIR‐ICG capable of optical imaging in vivo.
A Combinatorial Approach for Colorimetric Differentiation of Organic Solvents Based on Conjugated Polymer‐Embedded Electrospun Fibers
Authors: Yoon Jaewon , Jung Young‐Sik , Kim Jong‐Man
Published: December 2008

A combinatorial approach for the colorimetric differentiation of organic solvents is developed. A polydiacetylene (PDA)‐embedded electrospun fiber mat, prepared with aminobutyric acid‐derived diacetylene monomer PCDA‐ABA 1, displays colorimetric stability when exposed to common organic solvents. In contrast, a fiber mat prepared with the aniline‐derived diacetylene PCDA‐AN 2 undergoes a solvent‐sensitive color transition. Arrays of PDA‐embedded microfibers are constructed by electrospinning poly(ethylene oxide) solutions containing various ratios of two diacetylene monomers. Unique color patterns are developed when the conjugated polymer‐embedded electrospun fiber arrays are exposed to common organic solvents in a manner which enables direct colorimetric differentiation of the tested solvents.
A Unique Microcracking Process Associated with the Inelastic Deformation of Haversian Bone
Authors: Ebacher Vincent , Wang Rizhi
Published: December 2008

Since the discovery of the Haversian system in human bone over three hundred years ago, researchers have been wondering about its mechanical advantages. Despite positive experimental evidences on the intervention of Haversian systems in the fracture process, the contributions of Haversian systems to bone fracture have been obscure. Here a unique microcracking process accompanying the inelastic deformation of Haversian bone is reported that may shine light on its structural advantages over other bones. When compressed transversely, the concentric bone lamellae surrounding each Haversian canal allow multiple radial microcracks and arc‐shaped cracks to develop intralamellarly. Groups of circumferential arc‐shaped microcracks develop in high shear zones and radiate out in oblique directions from each Haversian canal. At the cortical bone level, where the Haversian systems are randomly distributed within the interstitial matrix, multiple nucleations and stable development of such arc‐shaped cracks happen to most Haversian systems progressively. As a result, Haversian bone is not sensitive to the presence of Haversian canals and demonstrates high inelastic strains at macroscopic level.
Shape‐Controlled Synthesis of Pd Nanocrystals in Aqueous Solutions
Authors: Lim Byungkwon , Jiang Majiong , Tao Jing , Camargo Pedro H. C. , Zhu Yimei , Xia Younan
Published: December 2008

This article provides an overview of recent developments regarding synthesis of Pd nanocrystals with well‐controlled shapes in aqueous solutions. In a solution‐phase synthesis, the final shape taken by a nanocrystal is determined by the twin structures of seeds and the growth rates of different crystallographic facets. Here, the maneuvering of these factors in an aqueous system to achieve shape control for Pd nanocrystals is discussed. L‐ascorbic acid, citric acid, and poly(vinyl pyrrolidone) are tested for manipulating the reduction kinetics, with citric acid and Br– ions used as capping agents to selectively promote the formation of {111} and {100} facets, respectively. The distribution of single‐crystal versus multiple‐twinned seeds can be further manipulated by employing or blocking oxidative etching. The shapes obtained for the Pd nanocrystals include truncated octahedron, icosahedron, octahedron, decahedron, hexagonal and triangular plates, rectangular bar, and cube. The ability to control the shape of Pd nanocrystals provides a great opportunity to systematically investigate their catalytic, electrical, and plasmonic properties.
Synthesis of Carbon‐Nanotube Composites Using Supercritical Fluids and Their Potential Applications
Authors: Liu Zhimin , Han Buxing
Published: December 2008

Carbon‐nanotube (CNT) composites have attracted a lot of attention because of their potential applications in many fields. Here, recent advances in the synthesis of CNT composites using supercritical fluids (SCFs) are highlighted. SCFs exhibit unique features for the synthesis of composites because of their unusual properties, such as low viscosity, high diffusivity, near‐zero surface tension, and tunability. Preliminary studies show that SCFs show unusual advantages for the synthesis of CNT composites. The morphologies and structures of the resultant CNT composites can be tuned by changing the solvent properties. The SCF methods not only provide a green route for the synthesis of composites, but also result in nanostructures that have not yet been produced by conventional methods. Moreover, the potential applications of the resultant CNT composites are also discussed.
Lanthanide‐Containing Light‐Emitting Organic–Inorganic Hybrids: A Bet on the Future
Authors: Carlos Luís D. , Ferreira Rute A. S. , Bermudez Verónica de Zea , Ribeiro Sidney J. L.
Published: December 2008

Interest in lanthanide‐containing organic–inorganic hybrids has grown considerably during the last decade, with the concomitant fabrication of materials with tunable attributes offering modulated properties. The potential of these materials relies on exploiting the synergy between the intrinsic characteristics of sol–gel derived hosts (highly controlled purity, versatile shaping and patterning, excellent optical quality, easy control of the refractive index, photosensitivity, encapsulation of large amounts of isolated emitting centers protected by the host) and the luminescence features of trivalent lanthanide ions (high luminescence quantum yield, narrow bandwidth, long‐lived emission, large Stokes shifts, ligand‐dependent luminescence sensitization). Promising applications may be envisaged, such as light‐emitting devices, active waveguides in the visible and near‐IR spectral regions, active coatings, and bio‐medical actuators and sensors, opening up exciting directions in materials science and related technologies with significant implications in the integration, miniaturization, and multifunctionalization of devices. This review provides an overview of the latest advances in Ln3+‐containing siloxane‐based hybrids, with emphasis on the different possible synthetic strategies, photoluminescence features, empirical determination
Polyurethane‐ and Polystyrene‐Supported 2,2,6,6‐Tetramethyl‐ piperidine‐1‐oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane Reactor
Authors: Subhani Muhammad Afzal , Beigi Maryam , Eilbracht Peter
Published: December 2008

In this contribution, the facile synthesis of two new polymer‐supported 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)‐ and polystyrene (PS)‐based TEMPO catalysts are prepared in a one‐step reaction from commercially available compounds. Both polymer‐supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co‐oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane‐supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated.
Ruthenium‐Catalyzed β‐Alkylation of Secondary Alcohols with Primary Alcohols
Authors: Cheung Hung Wai , Lee Ting Yan , Lui Ho Yin , Yeung Chi Hung , Lau Chak Po
Published: December 2008

Cyclopentadienyl (Cp), hydrotris(pyrazolyl)borato (Tp), and bipyridine ruthenium complexes were found to be active catalysts for the β‐alkylation of secondary alcohols with primary alcohols. Mechanistic aspects of the Cp and Tp complexes‐catalyzed reactions were investigated; the crucial hydrido complexes were identified. Carbonyl complexes resulting from aldehyde decarbonylation were formed in some cases, and surprisingly, they were also found to be active for the catalytic processes.
Ruthenium‐Indenylidene Complexes: Scope in Cross‐Metathesis Transformations
Authors: Boeda Fabien , Bantreil Xavier , Clavier Hervé , Nolan Steven P.
Published: December 2008

A comparative study examining the catalytic activity of a series of five indenylidene‐containing ruthenium complexes in olefin cross‐metathesis reactions is presented. Results reveal the greater efficiency of precatalyst 5, highlighting the key role of the N,N′‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr) ligand for this transformation. The scope of this precatalyst was investigated and several microwave experiments were carried out allowing for catalyst loadings as low as 0.1 mol%. Overall, cross‐metathesis products were isolated in moderate to excellent yields with high stereoselectivity.
β‐Hydroxycarboxylic Acids from Simple Ketones by Carboxylation and Asymmetric Hydrogenation
Authors: Flowers Brendan J. , Gautreau‐Service Robyn , Jessop Philip G.
Published: December 2008

We present a new asymmetric synthesis of β‐hydroxycarboxylic acids from ketones, performed by carboxylation using CO2 followed by asymmetric hydrogenation. First, the carboxylation of ketones gives β‐ketocarboxylic acids. The effects of temperature, reaction time, and amount of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) promoter on the carboxylation were investigated. The DBU can be recycled. For the second step, the asymmetric hydrogenation of these β‐ketocarboxylic acids, we determined the effect of solvent choice, H2 pressure, and substrate substitution. Hydrogenation yield and enantioselectivity are solvent‐dependent, and the mechanism could proceed through hydrogenation of either the enol or the keto forms of the bound substrate. This synthesis is industrially advantageous due to the limited number of reactants required, their low‐cost, and the potential for recycling unused materials.
Eco‐Friendly Olefin Dihydroxylation Catalyzed by Diphenyl Diselenide
Authors: Santoro Stefano , Santi Claudio , Sabatini Michela , Testaferri Lorenzo , Tiecco Marcello
Published: December 2008

The first general and efficient diphenyl diselenide‐catalyzed dihydroxylation of double bonds is presented. Hydrogen peroxide can be used as the oxidizing agent, affording generally good yields and high diasteroselectivity.
Wirkstofftransport mit weicher Materie: Matrix‐ und Vesikelvektoren
Authors: Soussan Elodie , Cassel Stéphanie , Blanzat Muriel , Rico‐Lattes Isabelle
Published: December 2008

Der zunehmende Bedarf an Transportsystemen, mit denen die Aktivität und Spezifität von Wirkstoffen verbessert, die Toxizität reduziert und so die Behandlungssicherheit maximiert werden kann, hat zur Entwicklung zahlreicher Wirkstoffvektoren geführt. Insbesondere Systeme auf der Basis von weicher Materie verfügen über interessante Merkmale. Hier beschreiben wir den aktuellen Kenntnisstand in diesem Gebiet, wobei wir uns hauptsächlich auf die beiden Gruppen der Matrixsysteme und Vesikel konzentrieren. Wir geben eine Übersicht über die Strukturen, Eigenschaften und Einsatzmöglichkeiten dieser Vektoren und diskutieren die wichtigsten Vor‐ und Nachteile bei ihrer Synthese.
Heterogeneously Hybridized Porous Coordination Polymer Crystals: Fabrication of Heterometallic Core–Shell Single Crystals with an In‐Plane Rotational Epitaxial Relationship
Authors: Furukawa Shuhei , Hirai Kenji , Nakagawa Keiji , Takashima Yohei , Matsuda Ryotaro , Tsuruoka Takaaki , Kondo Mio , Haruki Rie , Tanaka Daisuke , Sakamoto Hirotoshi , Shimomura Satoru , Sakata Osami , Kitagawa Susumu
Published: December 2008

MOF im MOF: Einkristalle eines porösen Kern‐Schale‐Koordinationspolymers (PCP) wurden durch epitaxiales Wachstum in Lösung erzeugt. Synchrotron‐Röntgenbeugungsmessungen offenbarten die strukturellen Beziehungen zwischen dem Kern‐ und Schalenkristall: Ein epitaxiales Wachstum in verdrehter Orientierung gleicht die unterschiedlichen Gitterkonstanten aus.

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Chemoselective Ligation and Modification Strategies for Peptides and Proteins
Authors: Hackenberger Christian P. R. , Schwarzer Dirk
Published: December 2008

The investigation of biological processes by chemical methods, commonly referred to as chemical biology, often requires chemical access to biologically relevant macromolecules such as peptides and proteins. Building upon solid‐phase peptide synthesis, investigations have focused on the development of chemoselective ligation and modification strategies to link synthetic peptides or other functional units to larger synthetic and biologically relevant macromolecules. This Review summarizes recent developments in the field of chemoselective ligation and modification strategies and illustrates their application, with examples ranging from the total synthesis of proteins to the semisynthesis of naturally modified proteins.
Solid‐State Scrolls from Hierarchical Self‐Assembly of T‐Shaped Rod–Coil Molecules
Authors: Hong Dong‐Je , Lee Eunji , Jeong Haemi , Lee Jeong‐kyu , Zin Wang‐Cheol , Nguyen Trung Dac , Glotzer Sharon C. , Lee Myongsoo
Published: December 2008

On a roll: Attachment of flexible coils to the middle of a rigid rod generates T‐shaped rod–coil molecules that self‐assemble into layers that roll up to form filled cylindrical and hollow tubular scrolls, depending on the coil length, in the solid state (see picture); the rods are arranged parallel to the layer plane.

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The role of trust in promoting organizational knowledge seeking using knowledge management systems: An empirical investigation
Authors: He Wei , Fang Yulin , Wei Kwok‐Kee
Published: December 2008

Knowledge Management Systems (KMS) have become increasingly popular as a knowledge‐sharing tool in contemporary corporations. Enticing employees to seek knowledge from KMS remains an important concern for researchers and practitioners. Trust has been widely recognized in many studies as an important enabling factor for seeking knowledge; however, the role of trust in promoting knowledge‐seeking behavior using KMS has not been adequately addressed. Drawing upon the extant literature on trust and information technology adoption, this article examines the relationships between the knowledge seekers' trust in the community of KMS users, their perceptions toward the system (perceived usefulness and perceived seeking efforts), and the intention to continually use the KMS. The results reveal that trust in the community of KMS users does not directly affect the employees' knowledge‐seeking continuance intention; rather, it happens indirectly through a mediated effect of perceived usefulness of the KMS. Furthermore, we find that trust seems to be a stronger determinant of perceived usefulness than of perceived seeking efforts. Our study thus demonstrates the indirect, but still crucial, role of trust in knowledge‐seeking behavior in the context of corporate KMS usage. Other findings and the implications of this study for both researchers and practitioners are correspondingly discussed.
Inclusion Behavior of β‐Cyclodextrin with Bipyridine Molecules: Factors Governing Host‐Guest Inclusion Geometries
Authors: Zhao Yan‐Li , Benítez Diego , Yoon Il , Stoddart J. Fraser
Published: December 2008

Guest Effect: The differences of nitrogen atom positions and the bridge bonds linked to two pyridine rings of some bipyridine guests can significantly affect the binding abilities and inclusion geometries of β‐cyclodextrin with the guests in both the solution and solid states.

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The 1:1 complexation of β‐cyclodextrin (β‐CD) with structurally similar bipyridine guests which lead to the formation of six inclusion complexes (1–6) of β‐CD with 4,4′‐vinylenedipyridine, 2,2′‐vinylenedipyridine, 1‐(2‐pyridyl)‐2‐(4‐pyridyl)ethylene, 4,4′‐ethylene‐dipyridine, 4,4′‐dithiodipyridine, and 2,2′‐dithiodipyridine has been investigated comprehensively by X‐ray crystallography in the solid state and by 1H NMR spectroscopy and microcalorimetric titration in aqueous solution. The complex formation constants (KS) for the stoichiometric 1:1 host–guest inclusion complexation of β‐CD with the bipyridine derivatives were determined in aqueous solution by microcalorimetry and the host–guest inclusion geometries of the complexes were deduced from 1H ROESY NMR spectroscopy. It transpires that the guest bipyridine molecules are included in the β‐CD cavity with a range of different inclusion geometries. In the solid state, the crystal superstructures for the β‐CD complexes 1, 4, and 5 are characterized by the triclinic crystal system (space group P1) commensurate with AAAA type supramolecular aggregation. By contrast, the β‐CD complexes 2, 3, and 6 display either monoclinic (space group P21) or orthorhombic (space group C2221) crystal systems, characteristic of ABAB type supramolecular aggregation. The results demonstrate that the relative locations of the nitrogen atom positions and the bridge‐bond links between the two pyridine rings in these bipyridine guests, not only lead to distinct crystal systems and space groups, but also to different binding geometries and thermodynamical parameters on complexation of the bipyridines with β‐CD. The knowledge obtained from this research improves our understanding of the molecular recognition and self‐assembly processes exhibited by β‐CD, both in the solid state and in aqueous solution.
900 MHz modulated electromagnetic fields accelerate the clathrin‐mediated endocytosis pathway
Authors: Moisescu Mihaela G. , Leveque Philippe , Verjus Marie‐Ange , Kovacs Eugenia , Mir Lluis M.
Published: December 2008

We report new data regarding the molecular mechanisms of GSM‐induced increase of cell endocytosis rate. Even though endocytosis represents an important physical and biological event for cell physiology, studies on modulated electromagnetic fields (EMF) effects on this process are scarce. In a previous article, we showed that fluid phase endocytosis rate increases when cultured cells are exposed to 900 MHz EMF similar to mobile phones' modulated GSM signals (217 Hz repetition frequency, 576 µs pulse width) and to electric pulses similar to the GSM electrical component. Trying to distinguish the mechanisms sustaining this endocytosis stimulation, we exposed murine melanoma cells to Lucifer Yellow (LY) or to GSM–EMF/electric pulses in the presence of drugs inhibiting the clathrin‐ or the caveolin‐dependent endocytosis. Experiments were performed at a specific absorption rate (SAR) of 3.2 W/kg in a wire patch cell under homogeneously distributed EMF field and controlled temperature (in the range of 28.5–29.5 °C). Thus, the observed increase in LY uptake was not a thermal effect. Chlorpromazine and ethanol, but not Filipin, inhibited this increase. Therefore, the clathrin‐dependent endocytosis is stimulated by the GSM–EMF, suggesting that the cellular mechanism affected by the modulated EMF involves vesicles that detach from the cell membrane, mainly clathrin‐coated vesicles. Bioelectromagnetics 30:222–230, 2009. © 2008 Wiley‐Liss, Inc.