bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclodextrins in Polymer Synthesis: Enzymatic Polymerization of a 2,6‐Dimethyl‐β‐Cyclodextrin/2,4‐Dihydroxyphenyl‐4′‐Hydroxybenzylketone Host‐Guest Complex Catalyzed by Horseradish Peroxidase (HRP)
Authors: Mejias Lorenzo , Schollmeyer Dieter , Sepulveda‐Boza Silvia , Ritter Helmut 
Published: July 2003

AbstractThis paper reports the enzymatic polymerization of the inclusion complex 2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone/2,6‐dimethyl‐β‐cyclodextrin by horseradish peroxidase (HRP) in aqueous media. The structure of the complex was determined by means of NOESY‐NMR and crystallographic analysis (indicating an orthorhombic structure). The enzymatic polymerization of the uncomplexed 2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone yields oligomers with molecular weights up to $\overline M _{\rm w} = 4 \times 10^3$ in organic‐aqueous media, but because of its poor solubility in aqueous systems, no polymerization is observed if water is used as solvent. An increase of the availability of the ketone in solution is achieved by complexing it with random‐methylated β‐cyclodextrin in water. We found that the use of methylated β‐cyclodextrin in equimolar concentration to the monomer increases the polymerization yield and the average molecular weight. The polymers formed were analyzed by GPC and ATR‐FTIR techniques.Representation from X‐ray diffraction analysis of the 2,6‐dimethyl‐β‐cyclodextrin/2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone host‐guest complex (3).magnified imageRepresentation from X‐ray diffraction analysis of the 2,6‐dimethyl‐β‐cyclodextrin/2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone host‐guest complex (3).
Synthesis of Strong Electrolyte Temperature‐Sensitive Hydrogels by Radiation Polymerization and Application in Protein Separation
Authors: Yang Hua , Song Weiqiang , Zhuang Yinfeng , Deng Xianmo 
Published: July 2003

AbstractStrong electrolyte temperature‐sensitive hydrogels were synthesized by radiation polymerization using N‐isopropylacrylamide and sodium 2‐acrylamido‐2‐methylpropanesulfonate. The influence of irradiation dose and mole ratio of the monomers was examined by swelling measurements in aqueous solution and organic solvents. The hydrogels without any pollution were applied in concentrating protein.Effect of irradiation dose on swelling ratios of P(NIPA‐co‐NaAMPS) hydrogels.magnified imageEffect of irradiation dose on swelling ratios of P(NIPA‐co‐NaAMPS) hydrogels.
Role of Water Activity on the Synthesis of Vinyl Thymidine Catalyzed by Protease from Bacillus Subtilis
Authors: Fan Hong , Kitagawa Masaru , Raku Takao , Tokiwa Yutaka 
Published: July 2003

AbstractThe transesterification activity of Bioprase, a protease from Bacillus subtilis, in dimethylformamide (DMF) is found to depend strongly on water addition. For the transesterification between thymidine and divinyl adipate by Bioprase in DMF with water (5–40%), the conversion rate of thymidine to the ester is much higher than the rate in DMF without the addition of water. For example, the transesterification reaction of 0.25 M thymidine with 1 M divinyl adipate in DMF in the presence of 10% water was catalyzed by Bioprase (50 mg · ml−1) at 30 °C for only 10–20 minutes to give 5′‐O‐vinyladipoyl thymidine (conversion ca. 90%), but the reaction did not proceed without the addition of water. Furthermore, the water effect is useful for the transesterification of thymidine with divinyl sebacate, which has a longer alkyl chain than divinyl adipate. This investigation showed that DMF adsorbs on the enzyme surface instead of essential water in the reaction of DMF without addition of water. On the other hand, in the reaction of DMF/water cosolvents, essential water bound to enzyme was not removed by DMF, and a higher transesterification activity occurs thereafter.Effect of water on the transesterification of thymidine catalyzed by Bioprase in DMF.magnified imageEffect of water on the transesterification of thymidine catalyzed by Bioprase in DMF.
Enzymatic Synthesis and Polymerization of Cyclic Trimethylene Carbonate Monomer with/without Methyl Substituent
Authors: Tasaki Hiroaki , Toshima Kazunobu , Matsumura Shuichi 
Published: July 2003

AbstractThe direct enzymatic synthesis of a cyclic trimethylene carbonate (1,3‐dioxane‐2‐one) monomer with/without a methyl substituent was carried out using dimethyl or diethyl carbonate and 1,3‐diol with the objective of producing aliphatic poly(trimethylene carbonate), a typical biodegradable synthetic plastic. The lipase‐catalyzed condensation of dimethyl or diethyl carbonate with aliphatic 1,3‐diols using immobilized Candida antarctica lipase (lipase CA) in an organic solvent at 70 °C afforded the corresponding methyl‐substituted and unsubstituted cyclic trimethylene carbonates. The cyclic trimethylene carbonates obtained by the reaction of dimethyl or diethyl carbonates with 1,3‐propanediol and 2‐methyl‐1,3‐propanediol were polymerized by lipase to produce the corresponding polycarbonates.Total TMC yield as a function of the reaction time.magnified imageTotal TMC yield as a function of the reaction time.
Applications of Defocusing DPIV to Bubbly Flow Measurement
Authors: Jeon David , Pereira Francisco , Gharib Morteza 
Published: July 2003

AbstractDefocusing digital particle image velocimetry (DDPIV) was used to investigate a bubbly flow in the wake of a hydrofoil. DDPIV is a three component volumetric velocimetry technique that operates at full video rate. Complex, three‐dimensional, and time‐dependent flows can be measured. To measure the bubble sizes, an extension to DDPIV was made to infer bubble sizes from their intensities. Both bubble size distributions and bubble velocity fields were simultaneously measured. Results indicate that DDPIV can reliably measure bubble sizes in the range of 100 microns, as well as resolving their aggregate motion.
Planar Droplet Sizing for the Characterization of Droplet Clusters in an Industrial Gun‐Type Burner
Authors: Zimmer Laurent , Ikeda Yuji 
Published: July 2003

AbstractAn important problem in spray combustion deals with the existence of dense regions of droplets, called clusters. To understand their formation mechanism, the droplet dynamics and fuel concentration profile are investigated by means of planar laser techniques in an industrial gun‐type burner. The simultaneous measurement of elastic Mie scattering and Laser Induced Fluorescence (LIF) allows the instantaneous measurement of the Sauter Mean Diameter (SMD), after proper calibration. Using two different CCDs to get the two signals requires a detailed calibration of the CCD response before getting absolute diameters. Pixels are binned 6 by 6 to obtain the final SMD map, this is a compromise between spatial accuracy and noise. Velocity field is measured on both sets of images using standard Particle Image Velocimetry (PIV) algorithms. The comparison of cross‐correlation technique with PDA results shows that the velocity measured on the LIF images are close to the velocity based on D30, whereas the Mie scattering results are similar to D20. On Mie scattering images, regions of high interfacial area forming clusters can be detected. A special tracking scheme is used to characterize their dynamics in terms of velocity and diameters by ensuring that the same volume of fluid is tracked. It is shown that the clusters have a velocity similar to the velocity of droplets with the same diameter as the mean SMD of the cluster. It is also shown that an increase of pressure tends to trigger the appearance of such a group of droplets, due to a smaller diameter of the droplets caused by the increase of pressure discharge. Uncertainties for the different techniques used are discussed.
Centrifugal partition chromatography: A survey of its history, and our recent advances in the field
Authors: Marchal Luc , Legrand Jack , Foucault Alain 
Published: July 2003

AbstractCentrifugal partition chromatography (CPC) was introduced in 1982 by Sanki Eng. And for almost 20 years this company remained the only one manufacturing such an apparatus. A CPC instrument or a CPC column is a series of channels linked in cascade by ducts and aligned in cartridges or disks in a circle around a rotor; setting the rotor in motion submits this assembly to a constant centrifugal field. The originality of CPC is that it uses any biphasic liquid‐liquid system as mobile and stationary phases. The United States branch of Sanki contributed greatly to the worldwide acceptance of the technique. Recent works performed in the Netherlands and in France have, by means of visualization of flow‐patterns in CPC channels, contributed to a better knowledge of hydrodynamics and mass transfer phenomena. Nowadays research in our laboratory focuses on speediness and scale‐up of the technique. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 133–143; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10057
Microbial genes and enzymes in the degradation of chlorinated compounds
Authors: Ogawa Naoto , Miyashita Kiyotaka , Chakrabarty A. M. 
Published: July 2003

AbstractMicroorganisms are well known for degrading numerous natural compounds. The synthesis of a multitude of chlorinated compounds by the chemical industry and their release into the natural environment have created major pollution problems. Part of the cause of such pollution is the inability of natural microorganisms to efficiently degrade synthetic chlorinated compounds. Microorganisms are, however, highly adaptable to changes in the environment and have consequently evolved the genes that specify the degradation of chlorinated compounds to varying degrees. Highly selective laboratory techniques have also enabled the isolation of microbial strains capable of utilizing normally recalcitrant highly chlorinated compounds as their sole source of carbon and energy. The evolution and role of microbial genes and enzymes, as well as their mode of regulation and genetic interrelationships, have therefore been the subjects of intense study. This review emphasizes the genetic organization and the regulation of gene expression, as well as evolutionary considerations, regarding the microbial degradation of chlorobenzoates, chlorocatechols, and chlorophenoxyacetic acids. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 158–171; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10059
Cluster, facets, and edges: Site‐dependent selective chemistry on model catalysts
Authors: Freund H.‐J. , Libuda J. , Bäumer M. , Risse T. , Carlsson A. 
Published: July 2003

AbstractMore than activity, selectivity of catalytic reactions is the focus of research in the 21st century. We review studies on model systems that address the issue of directing a catalytic reaction on disperse metal catalysts by controlling the specific surface site. Three examples are explored: methanol dehydrogenation over Pd/alumina, NO dissociation on Pd/alumina, and reaction studies for molecules relevant in a Fischer‐Tropsch scenario on a bimetallic Pd/Co/alumina model catalyst. We show how surface science can be used by combining a variety of experimental techniques to study the chemistry of model catalysts at the atomic level. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 181–200; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10060
New reactions of 1‐alkynes catalyzed by transition metal complexes
Authors: Wakatsuki Yasuo , Hou Zhaomin , Tokunaga Makoto 
Published: July 2003

AbstractRecently discovered catalytic reactions with ruthenium and lanthanide metal complexes have extended the scope of 1‐alkynes as useful reagents. The specific formation of aryl‐substituted (Z)‐1,3‐enynes via the dimerization of HCCR1 (R1 = aryl) has been attained using dimeric lanthanide complexes, the catalytic activity of which appears to be unaffected by time. The dimerization of HCCR2 (R2 = t‐Bu, SiMe3) catalyzed by Ru(cod)(cot)/PR3 or RuH2(PPh3)3 produces a good yield of butatrienes (Z)‐R2CHCCCHR2 with a high degree of selectivity. Under certain conditions, HCCSiMe3 dimerizes to yield exclusively (Z)‐M3SiCCCHCHSiMe3. The hydration of HCCR3 (R3 = alkyl, aryl) catalyzed by RuCl2/PR′3 or CpRuCl(PR″3)2 has realized the first example of anti‐Markovnikov regioselectivity in an addition reaction of water that produces aldehydes R3CH2CHO. The application of this reaction to propargylic alcohols has lead to their formal isomerization to α,β‐unsaturated aldehydes. In contrast, the addition of amines R4NH2 (R4 = aryl) to HCCR5 (R5 = alkyl, aryl) conforms to Markovnikov's rule to produce ketimines R5(CNR4)CH3 when catalyzed by a Ru3(CO)12/additive. Since the reaction can be performed in air without the need for any solvents, it enables the practical synthesis of aromatic ketimines, which are difficult to prepare by conventional methods. The synthesis of indoles using deactivated anilines is one practical application of this reaction. The mechanisms of some of these reactions have been analyzed in detail with the aid of theoretical calculations. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 144–157; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10061
Pulmonary responses of acute exposure to ultrafine iron particles in healthy adult rats
Authors: Zhou Ya‐Mei , Zhong Cai‐Yun , Kennedy Ian M. , Pinkerton Kent E. 
Published: July 2003

AbstractAs critical constituents of ambient particulate matter, transition metals such as iron may play an important role in health outcomes associated with air pollution. The purpose of this study was to determine the respiratory effects of inhaled ultrafine iron particles in rats. Sprague Dawley rats 10–12 weeks of age were exposed by inhalation to iron particles (57 and 90 μg/m3, respectively) or filtered air (FA) for 6 h/day for 3 days. The median diameter of particles generated was 72 nm. Exposure to iron particles at a concentration of 90 μg/m3 resulted in a significant decrease in total antioxidant power along with a significant induction in ferritin expression, GST activity, and IL‐1β levels in lungs compared with lungs of the FA control or of animals exposed to iron particles at 57 μg/m3. NFκB–DNA binding activity was elevated 1.3‐fold compared with that of control animals following exposure to 90 μg/m3 of iron, but this change was not statistically significant. We concluded that inhalation of iron particles leads to oxidative stress associated with a proinflammatory response in a dose‐dependent manner. The activation of NFκB may be involved in iron‐induced respiratory responses, but further studies are merited. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 227–235, 2003.
Effect of Microcystis aeruginosa and Nodularia spumigena on survival of Eurytemora affinis and the embryonic and larval development of the Baltic herring Clupea harengus membras
Authors: Ojaveer Evald , Simm Mart , Balode Maija , Purina Ingrida , Suursaar Ülo 
Published: July 2003

AbstractLaboratory experiments were carried out to investigate the effect of two strains of Microcystis aeruginosa and a strain of Nodularia spumigena on the survival of Eurytemora affinis (Copepoda) and on the embryonic and larval development of the Baltic spring‐spawning herring Clupea harengus membras. The trials were made in water taken from Pärnu Bay, at a salinity of 3.7–5.1 psu, a constant temperature (15°C ± 1°C in trials with Eurytemora and herring embryos; 18°C ± 2°C with herring larvae), and an oxygen concentration of 8.8–10.4 ppm. The strains tested had a negative impact on the survival of Eurytemora, as well as on the embryonic development and hatching regime of the Baltic herring. In Eurytemora the response depended on the sex of the animals: the survival was clearly higher in females. In the embryonic stages of herring, the influence resulted in an increase in deviations from the normal pattern of development and a higher mortality. The impact of the strains on the larval development of herring was rather moderate. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 236–242, 2003.
Neurotransmitter release: the dark side of the vacuolar‐H+ATPase
Authors: Morel N. 
Published: July 2003

AbstractVacuolar‐H+ATPase (V‐ATPase) is a complex enzyme with numerous subunits organized in two domains. The membrane domain V0 contains a proteolipid hexameric ring that translocates protons when ATP is hydrolysed by the catalytic cytoplasmic sector (V1). In nerve terminals, V‐ATPase generates an electrochemical proton gradient that is acid and positive inside synaptic vesicles. It is used by specific neurotransmitter‐proton antiporters to accumulate neurotransmitters inside their storage organelles. During synaptic activity, neurotransmitters are released from synaptic vesicles docked at specialized portions of the presynaptic plasma membrane, the active zones. A fusion pore opens that allows the neurotransmitter to be released from the synaptic vesicle lumen into the synaptic cleft. We briefly review experimental data suggesting that the membrane domain of V‐ATPase could be such a fusion pore. We also discuss the functional implications for quantal neurotransmitter release of the sequential use of the same V‐ATPase membrane domain in two different events, neurotransmitter accumulation in synaptic vesicles first, and then release from these organelles during synaptic activity.
Calmodulin‐dependent regulation of a lipid binding domain in the v‐SNARE synaptobrevin and its role in vesicular fusion
Authors: De Haro Luc , Quetglas Stéphanie , Iborra Cécile , Lévêque Christian , Seagar Michael 
Published: July 2003

AbstractTrans SNARE complex assembly is an essential step in Ca2+‐dependant membrane fusion, although the SNARE proteins do not bind Ca2+ ions. Studies to evaluate how the Ca2+sensor protein calmodulin might regulate this process led to the identification of a consensus calmodulin binding motif in the v‐SNARE VAMP2. This sequence (residues 77–90) is situated precisely C‐terminal to the tetanus toxin (TeNT) and botulinum B toxin cleavage site (76Q‐F77) close to the transmembrane anchor. The same domain also binds acidic phospholipids and Ca2+/calmodulin or lipid binding are mutually exclusive. Directed mutagenesis of basic or hydrophobic residues within this motif reduced interactions with both Ca2+/calmodulin and phospholipids to a similar extent. The effects of these mutations on Ca2+‐dependent exocytosis was explored using an hGH release assay in permeabilized pheochromocytoma PC12 cells. Treatment of cells with tetanus toxin (TeNT), which cleaves endogenous VAMP, abolished secretion. Secretion could be re‐established by transfecting TeNT‐resistant VAMP with mutations (Q76V, F77W) in the cleavage site. However rescue of exocytosis was abolished when additional mutations (K83A, K87V or W89A, W90A) were introduced that inhibited calmodulin and phospholipid binding to VAMP. Thus calmodulin and/or phospholipid binding to the membrane proximal region of VAMP is required for Ca2+‐dependent exocytosis. We speculate that interactions between cis phospholipids at the vesicle surface and the membrane proximal region of VAMP inhibits SNARE complex assembly. Displacement of these interactions by Ca2+/calmodulin may promote SNARE complex assembly and lead to trans interactions between the membrane proximal region of VAMP and phospholipids in the plasma membrane.
The nature of anterior knee pain following injection of hypertonic saline into the infrapatellar fat pad
Authors: Bennell Kim , Hodges Paul , Mellor Rebecca , Bexander Catharina , Souvlis Tina 
Published: July 2003

AbstractThe infrapatellar fat pad has been implicated as a possible source of anterior knee pain. This study examined the nature, distribution and time‐course of experimentally induced pain in the infrapatellar fat pad. Hypertonic saline (5%) was injected into the medial fat pad of 11 healthy individuals with no history of knee pain. Severity of pain was assessed at rest and during activity using an 11 point numerical rating scale (NRS) at regular intervals over 15–30 min following injection. Participants described the size of the pain region from a series of different sized circles while the area and type of pain was established from a body chart and the McGill pain questionnaire. The effect of pain on temperature‐pain threshold and sensory thresholds of the anterior knee was assessed. Participants generally reported a deep aching pain that peaked in severity around 3 min and gradually declined over 15 min. Pain levels were not altered by clinical manoeuvres designed to impinge the fat pad. The size of the pain region was related to pain intensity. Pain was most commonly felt in the region of the fat pad medial to the patella, although some individuals reported proximal referred pain as far as the groin region. Thermal and sensory thresholds were not altered at a region close to the injection site during the experimental pain. These results suggest that nociceptive stimulation of the infrapatellar fat pad may cause anterior knee pain that is not necessarily confined locally particularly if pain is severe. This has implications for the investigation of pathological structures in patients presenting clinically with anterior knee pain and provides an experimental model of anterior knee pain. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Lead induced effects on acetylcholinesterase activity in cerebellum and hippocampus of developing rat
Authors: Reddy Gottipuolu R. , Basha Md.Riyaz , Devi C.Bhuvaneswari , Suresh Ambati , Baker John L. , Shafeek Abdul , Heinz Josephine , Chetty Chellu S. 
Published: July 2003

AbstractExposure to low‐levels of lead (Pb) during early development has been implicated in behavioral abnormalities and cognitive deficits in children. The present study is focused on developmental changes in hippocampus and cerebellum of rats following perinatal exposure to Pb. Pregnant rats were exposed to 0.2% Pb‐acetate from gestation day 6 (GD 6) through postnatal day (PND) 21 and the activity levels of acetylcholinesterase (AChE) were estimated in cerebellum and hippocampus of pups at specific time points for 5 weeks. In both the brain regions, Pb‐exposure decreased AChE activity with an increase in age. Histochemical observations conducted in 35 days old rat brain showed decreased AChE activity conspicuously in stratum oriens and dentate gyrus of hippocampus, and molecular and granule cell layers of cerebellum. In vitro studies conducted in 35 days old rat brain showed a considerable decrease in the specific activity of AChE at high concentrations (50–100 μM) of Pb in a concentration‐dependent manner. However, at low concentrations (5–20 μM), Pb failed to produce such changes. In the presence of eserine (physostigmine), the specific inhibitor of AChE, the inhibitory effect of Pb was potentiated and this was more pronounced at low‐concentrations of Pb. The behavioral responses in open‐field also showed a significant decrease in both Pb exposed as well as eserine administered rats. These data suggest that low‐level perinatal Pb‐exposure induces alterations in cholinergic system in the cerebellum and hippocampus of developing brain even after the withdrawal of Pb‐exposure, that may contribute to behavioral and learning deficits.