bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternative mechanisms of gene amplification in human cancers
Authors: Kuwahara Yoshitaka , Tanabe Chikako , Ikeuchi Tatsuro , Aoyagi Kazuhiko , Nishigaki Michiko , Sakamoto Hiromi , Hoshinaga Kiyotaka , Yoshida Teruhiko , Sasaki Hiroki , Terada Masaaki 
Published: July 2004

AbstractGene amplification is a common phenomenon in cancer. Cytogenetic analyses have indicated that breakage‐fusion‐bridge (BFB) cycles drive intrachromosomal amplification of some oncogenes in a head‐to‐head manner in human cancers. However, the complex structures of an amplified sequence found in cancers are not always explained by the BFB model. At the 17q21 locus, which is not linked to common fragile sites, we discovered a recombination hot spot harboring amplicon repeats in tandem in a head‐to‐tail orientation, with the interamplicon junctions in each cancer cell being homogeneous. These findings clearly show the presence of alternative mechanisms other than BFB cycles in oncogene amplification. © 2004 Wiley‐Liss, Inc.
Recursive constructions for optimal (n,4,2)‐OOCs
Authors: Chu Wensong , Colbourn Charles J. 
Published: July 2004

AbstractIn [3], a general recursive construction for optical orthogonal codes is presented, that guarantees to approach the optimum asymptotically if the original families are asymptotically optimal. A challenging problem on OOCs is to obtain optimal OOCs, in particular with λ > 1. Recently we developed an algorithmic scheme based on the maximal clique problem (MCP) to search for optimal (n, 4, 2)‐OOCs for orders up to n = 44. In this paper, we concentrate on recursive constructions for optimal (n, 4, 2)‐OOCs. While “most” of the codewords can be constructed by general recursive techniques, there remains a gap in general between this and the optimal OOC. In some cases, this gap can be closed, giving recursive constructions for optimal (n, 4, 2)‐OOCs. This is predicated on reducing a series of recursive constructions for optimal (n, 4, 2)‐OOCs to a single, finite maximal clique problem. By solving these finite MCP problems, we can extend the general recursive construction for OOCs in [3] to obtain new recursive constructions that give an optimal (n · 2x, 4, 2)‐OOC with x ≥ 3, if there exists a CSQS(n). © 2004 Wiley Periodicals, Inc.
Production of β‐galactosidase from recombinant Saccharomyces cerevisiae grown on lactose
Authors: Domingues Lucília , Oliveira Carla , Castro Inês , Lima Nelson , Teixeira José A 
Published: July 2004

AbstractImproved productivity and costs reduction in fermentation processes may be attained by using flocculating cell cultures. The production of extracellular heterologous β‐galactosidase by recombinant flocculating Saccharomyces cerevisiae cells, expressing the lacA gene (coding for β‐galactosidase) of Aspergillus niger under the ADHI promotor and terminator in a bioreactor was studied. The effects of lactose concentration and yeast extract concentration on β‐galactosidase production in a semi‐synthetic medium were analysed. The extracellular β‐galactosidase activity increased linearly with increasing initial lactose concentrations (5–150 g dm−3). β‐Galactosidase production also increased with increased yeast extract concentration. During the entire fermentation, no accumulation of the hydrolysed sugars, glucose and galactose, was observed. The catabolic repression of the recombinant strain when cultured in a medium containing equal amounts of glucose and galactose was confirmed. In complete anaerobiosis, the fermentation of lactose resulted in a very slow fermentation pattern with lower levels of β‐galactosidase activity. The bioreactor operation together with optimisation of culture conditions (lactose and yeast extract concentration) led to a 21‐fold increase in the extracellular β‐galactosidase activity produced when compared with preliminary Erlenmeyer fermentations. Copyright © 2004 Society of Chemical Industry
Chloride‐promoted leaching of chalcopyrite concentrate by biologically‐produced ferric sulfate
Authors: Kinnunen Päivi H‐M , Puhakka Jaakko A 
Published: July 2004

AbstractThe effects of chloride ions on chalcopyrite leaching by biologically‐produced ferric sulfate solution and on the iron‐oxidizing culture were determined. Chloride ions significantly increased chalcopyrite leaching by ferric sulfate at 67 °C and 87 °C, but slowed down the leaching at 50 °C. At 90 °C, chloride at 5 g dm−3 (0.25 g Cl− g−1 concentrate) increased the copper yield from 60 to 100% in approximately 2 weeks. Further increase in Cl− concentration did not affect the leaching. Addition of chloride increased both leaching yields and iron precipitation, which shows that the passivation was not due to iron precipitation. A decreased Ag‐potential of 60 mV against an Ag/AgCl reference electrode in the presence of Cl− indicates the accumulation of partially oxidized forms of dissolved sulfur compounds such as thiosulfate and polythionate instead of elemental sulfur and, thus, a decrease in sulfur passivation. A chloride concentration of 5 g dm−3 did not affect the iron oxidation rate of the iron‐oxidizing culture dominated by Leptospirillum ferriphilum. Copyright © 2004 Society of Chemical Industry
Optimization of the production of chitosan from beet molasses by response surface methodology
Authors: Göksungur Y 
Published: July 2004

AbstractChitosan was produced by Rhizopus oryzae 00.4367 in shake flask culture and a stirred tank fermenter. Synthetic medium, treated and untreated beet molasses were used as cultivation media in shake flask cultures. In the stirred tank fermenter, the cultivation media were synthetic medium and untreated beet molasses. Shake flask culture containing untreated molasses with a sugar concentration of 40 g dm−3 produced the maximum chitosan yield (961 mg dm−3). Chitosan concentration reached its maximum value at the late exponential growth phase of R oryzae. In all experiments almost 8–10% of biomass and 32–38% of alkali‐insoluble material was extracted as chitosan. A central composite design was employed to determine the optimum values of process variables (aeration rate, agitation speed and initial sugar concentration) leading to maximum chitosan concentration in the stirred tank fermenter. In all cases, the fit of the model was found to be good. Aeration rate, agitation speed and initial sugar concentration had a strong linear effect on chitosan concentration. Moreover, the concentration of chitosan was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions. A maximum chitosan concentration of 1109.32 mg dm−3 was obtained in untreated molasses medium containing an initial sugar concentration of 45.37 g dm−3 with an aeration rate and agitation speed of 2.10 vvm and 338.93 rpm, respectively. Copyright © 2004 Society of Chemical Industry
Chemical treatment of cork‐processing wastewaters for potential reuse
Authors: Acero Juan L , Benitez F Javier , Heredia Jesus Beltran de , Leal Ana I 
Published: July 2004

AbstractThe chemical treatment of cork‐processing wastewater by ozonation, alone and in combination with hydrogen peroxide and UV radiation was investigated. A reduction of the chemical oxygen demand (COD) ranging from 42% to 76% was obtained during ozonation after 3 h of reaction, depending on the experimental conditions. The additional presence of hydrogen peroxide and UV radiation enhanced the efficiency of the ozonation treatment due to the contribution of the OH radicals formed in the decomposition of ozone. Thus, final reductions of the COD higher than 90% and a complete elimination of phenolic compounds and absorbance at 254 nm were achieved in both Advanced Oxidation Processes (AOPs), O3/H2O2 and O3/UV. Therefore the effluent resulting from the ozonation treatments can be reused in the cork‐processing industry. In a second step, the chemical treatment was conducted by means of UV radiation alone and by the action of hydroxyl radicals, which were generated by the following AOPs: UV/H2O2, Fenton's reagent, and photo‐Fenton system. The single photochemical process resulted in 9% of the organic matter present being removed, while the AOPs significantly enhanced this reduction with values in the range 20–75%. Kinetic studies for both groups of treatments were performed, and apparent kinetic rate constants were evaluated. In the ozone‐based experiments, the rate constants ranged from 1846 to 10922 dm3 mol−1 O3 h−1, depending on the operating conditions. In the oxidation experiments using oxidants other than ozone, the rate constants varied between 0.06 and 1.19 h−1. Copyright © 2004 Society of Chemical Industry
Wet oxidation pre‐treatment of woody yard waste: parameter optimization and enzymatic digestibility for ethanol production
Authors: Lissens Geert , Klinke Helene , Verstraete Willy , Ahring Birgitte , Thomsen Anne Belinda 
Published: July 2004

AbstractWoody yard waste with high lignin content (22% of dry matter (DM)) was subjected to wet oxidation pre‐treatment for subsequent enzymatic conversion and fermentation. The effects of temperature (185–200 °C), oxygen pressure (3–12 bar) and addition of sodium carbonate (0–3.3 g per 100 g DM biomass) on enzymatic cellulose and hemicellulose (xylan) convertibility were studied. The enzymatic cellulose conversion was highest after wet oxidation for 15 min at 185 °C with addition of 12 bars of oxygen and 3.3 g Na2CO3 per 100 g waste. At 25 FPU (filter paper unit) cellulase g−1 DM added, 58–67% and 80–83% of the cellulose and hemicellulose contained in the waste were converted into monomeric sugars. The cellulose conversion efficiency during a simultaneous saccharification and fermentation (SSF) assay at 10% DM was 79% for the highest enzyme loading (25 FPU g−1 DM) while 69% conversion efficiency was still reached at 15 FPU g−1 DM. Total carbohydrate recoveries were high (91–100% for cellulose and 72–100% for hemicellulose) and up to 49% of the original lignin and 79% of the hemicellulose could be solubilized during wet oxidation treatment and converted into carboxylic acids mainly (total carboxylic acids = 3.1–7.4% on DM basis). Copyright © 2004 Society of Chemical Industry
Optimization of polymerase chain reaction‐amplified conditions using the uniform design method
Authors: Cao Yang , Zheng Yuanyuan , Fang Baishan 
Published: July 2004

AbstractPolymerase chain reaction (PCR) is a key procedure in modern molecular biology but may be adversely affected by many factors and it is difficult to optimize reaction conditions; a technically simple and effective method to set up an optimal PCR‐amplified system is required. Uniform design (UD) is a method that enables many factors to be investigated. For example, thedhaTgene fromKlebsiella pneumoniaewas amplified and the optimization of the amplified parameters including concentration of Mg2+, annealing temperature, annealing time and number of cycles based on UD was reported. After only 12 experimental trials, an optimal PCR‐amplified result was obtained, demonstrating the value of UD for optimization of PCR. Copyright © 2004 Society of Chemical Industry
Test of flow field on the annular meridian plane in a tubular membrane separator with rotary tangential flow
Authors: Wang Cheng Duan , Jiang Guang Ming , Chen Wen Mei 
Published: July 2004

AbstractEnhancement of membrane microfiltration by rotary tangential flow is a new technique, which is based on the hydrocyclone mechanism. It improved the structure of the general membrane separator and the form of the liquid suspension flowing into the separator, so as to increase membrane fluxes and decrease membrane fouling. In our research, a tubular membrane separator with rotary tangential flow was designed for the first time. The flow field characteristics of polypropylene tubular membrane microfiltration in this tubular separator were studied systematically by means of the Particle Image Velocimetry (PIV) test. Streamlines and velocity distributions of the meridian plane of the separator under different operating parameters were obtained. The velocity distribution characteristics of rotary circular tangential flow were analyzed quantitatively with the following conclusions being obtained:

In the non‐vortex area, no matter how the operating parameters (flux, entry pressure) change, the velocity near the rotary tangential flow entrance is higher than the velocity far from the entrance at the same radial coordinates. In the vortex area, generally the flow velocity of the inner vortex is lower than that of the outer vortex. At the vortex center, the velocity is the lowest, the radial velocity being generally equal to zero. In the vortex zone, the radial velocity is less than the axial velocity.
Under test conditions, the radial velocity and the axial velocity of the vortexes' borders are 1–2 times the average axial velocity in the annular gap of the membrane module. The maximum radial velocity and axial velocity of Taylor vortexes are 2–5 times the average axial velocity in the annular gap of the membrane module.
In the vortexes that formed on the meridian plane, it was found that mass transfer occurred between the inner and outer parts of the fluid. Much fluid moved from the outer vortexes into the inner ones, which was able to prevent particles blocking the membrane tube.
Copyright © 2004 Society of Chemical Industry
Performance of fractionating reactors in the absence of rate limitations
Authors: den Hollander Jeroen L , Straathof Adrie JJ , van der Wielen Luuk AM 
Published: July 2004

AbstractA fractionating reactor for equilibrium‐limited reactions is studied theoretically. Reactant A is fed in the center of the countercurrent fractionating system. Product P is effectively transported with the auxiliary phase, while product Q is effectively transported with the main phase, in which the reaction takes place. Model calculations were based on partition and reaction equilibrium at all stages. These show that if the initial reactant concentration and the flow rates are properly selected, the extent of conversion will significantly exceed the corresponding batch conversion. To approach complete conversion in the fractionating reactor, and to recover both products in a pure form, net transport of reactant in either of the countercurrent directions should be prevented. However, irrespective of the number of equilibrium stages, this situation cannot be fully reached when the reactant feed stream is too large (compared with the main and auxiliary streams). Nonetheless, one of the two products may be recovered in a pure form even for such large feed streams. Copyright © 2004 Society of Chemical Industry
Separation of racemic 2,4‐dinitrophenyl amino acids on zirconia‐immobilized quinine carbamate in reversed‐phase liquid chromatography
Authors: Park Jung Hag , Lee Joon Woo , Song Young Tae , Ra Chun Sup , Cha Jin Soon , Ryoo Jae Jeong , Lee Wonjae , Kim In Whan , Jang Myung Duk 
Published: July 2004

AbstractZirconia is known to be one of the best chromatographic support materials due to its excellent chemical, thermal, and mechanical stability. A quinine carbamate‐coated zirconia was prepared as a chiral stationary phase for separation of enantiomers of DNP‐amino acids in reversed‐phase liquid chromatography. Retention and enantioselectivity of this phase were compared to those for quinine carbamate bonded onto silica. Most amino acids studied were separated on the quinine carbamate‐zirconia CSP although retention was longer and chiral selectivity was somewhat lower than on the corresponding silica CSP. Increased retention and decreased selectivity are probably due to strong non‐enantioselective Lewis acid‐base interactions between the amino acid molecule and the residual Lewis acid sites on the zirconia surface.
A preliminary approach to the separation of Leishmania cell‐surface antigens
Authors: Aksoy Nurten , Ozbilge Hatice , Keles Sait , Iriadam Mehmet , Vural Hüseyin , Akcay Fatih 
Published: July 2004

AbstractThe purpose of the current study was to characterize Leishmania cell‐surface antigens by two different methods established for the purification of glycoproteins and proteins, and to point out a useful approach to define their size and mass heterogeneity. L. tropica parasites were initially isolated from patients with active cutaneous leishmaniasis and were then cultured in vitro. The parasite‐cell layer was solubilised with 6 M guanidinium chloride (GuHCl) and subsequently prepared for the purification procedure. The methods used in this work were gel filtration chromatography and isopycnic density‐gradient centrifugation. Because of the presence of a substantial amount of non‐specific proteins in the culture medium, these methods were not effective alone in distinguishing these antigens. However, a good idea of their N‐glycosylated structures could be obtained by using Periodic acid‐Schiffs (PAS) and Con A lectin, and also size and mass heterogeneity. A combination of these methods effected a clear separation of the antigens. Amino acid analysis of the purified antigens was performed to positively identify them as well‐known Leishmania cell‐surface antigen gene products. The results confirmed the presence of more than one cell‐surface antigen on the Leishmania parasite and the combination of gel chromatography and density‐gradient centrifugation could be useful for their isolation.
Polypropylene Made with In‐Situ Supported Me2Si(Ind)2ZrCl2 and Me2Si(2‐Me‐Ind)2ZrCl2 Catalysts: Properties Comparison
Authors: Franceschini Fernando C. , da R. Tavares Tatiana T. , dos Santos João H. Z. , Soares João B. P. 
Published: July 2004

AbstractSummary: Propylene homopolymerizations were carried out using Me2Si(Ind)2ZrCl2 and Me2Si(2‐Me‐Ind)2ZrCl2, MAO‐modified silica, and common alkylaluminum cocatalysts. Supported catalysts were prepared by the in‐situ immobilization technique. The effect of the type and concentration of alkylaluminum on propylene polymerization was evaluated using TEA (triethylaluminum), IPRA (isoprenylaluminum), and TIBA (triisobutylaluminum) as cocatalysts. The polymers were analyzed by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and scanning electronic microscopy (SEM). The effect of the type and concentration of alkylaluminum on the melting temperature and the molar mass of the polypropylene was the same for both catalysts. The polymers made with in‐situ supported catalyst had lower melting points and, in almost all polymerization conditions, higher molar masses than those produced by homogeneous polymerization. Polypropylene samples made with Me2Si(2‐Me‐Ind)2ZrCl2 had higher melting temperatures and molar masses than those made with Me2Si(Ind)2ZrCl2. SEM micrographs showed that the polymers obtained with in‐situ supported systems had a well‐defined morphology, confirming that the polymerization indeed took place onto the silica support.SEM micrographs of polypropylene particles obtained with Me2Si(2‐Me‐Ind)2ZrCl2 in the presence of IPRA.magnified imageSEM micrographs of polypropylene particles obtained with Me2Si(2‐Me‐Ind)2ZrCl2 in the presence of IPRA.
Oriented Quiescent Crystallization of Polyethylene Studied by USAXS
Authors: Stribeck Norbert , Almendarez Camarillo Armando , Cunis Sabine , Bayer Rüdiger K. , Gehrke Rainer 
Published: July 2004

AbstractSummary: Highly oriented high‐pressure injection‐molded (HPIM) rods from polyethylene (PE) were heated until the discrete small‐angle X‐ray scattering (SAXS) had vanished. Thereafter, non‐isothermal and isothermal crystallization was investigated in situ by means of ultra small‐angle X‐ray scattering (USAXS). The orientation of the crystallites could be controlled by choice of the melt annealing temperature (shish‐kebab model: memory or self‐nucleation effect caused by stable shishs). Both the scattering patterns and the multidimensional chord distribution function (CDF) were interpreted. A three‐stage model of crystallization was also developed. This model comprises row structure nucleation, the almost statistical insertion of extended lamellae and finally the insertion of blocky crystallites. It was found that the nanostructure evolution in the isotropic fraction of the material was the same as in the highly oriented one. The lateral extension of the lamellae was largest during isothermal crystallization. The correlation among domains was increased by non‐isothermal crystallization. The shishs in the core of the HPIM rod appeared less stable than those in the shell. Lobe‐shaped reflections observed during and after quenching were not due to an orientation distribution of layer stacks, but reflected a correlation between long period and lateral extension of crystallites. During quenching, a lateral modulation of the layer peaks in the CDF grew stronger and showed the arrangement of block‐shaped crystals proposed by Strobl to be the precursors of lamellae. The thin crystals formed during rapid cooling were built from a central block surrounded by one or two rings of satellites. The long period observed in the scattering pattern during quenching is due to correlations among crystalline blocks in a chain, and not from correlations among lamellae.USAXS scattering patterns from isothermal, oriented crystallization of HPIM‐PE material (bottom row: during final quenching after 30 min at 127 °C).magnified imageUSAXS scattering patterns from isothermal, oriented crystallization of HPIM‐PE material (bottom row: during final quenching after 30 min at 127 °C).
Oriented Quiescent Crystallization of Polyethylene Studied by USAXS.
Authors: Stribeck Norbert 
Published: July 2004

AbstractSummary: In Part 1 of this series, the results of an in situ small‐angle X‐ray scattering (SAXS) study of polyethylene crystallization were presented. They showed that crystallite placement was basically a random process, from which some order is growing. This paper presents a first survey concerning the required change of paradigm. No distortion of a lattice is to be studied, but order grown on the nanometer scale must be distinguished from the stochastic case, i.e. the “car parking problem” from the field of random sequential adsorption (RSA). RSA is explored by computer simulation. The results concerning the corresponding liquid scattering are required to identify short‐range order (cf. Part 3). Processing of the simulated scattering patterns verified that the features of quasi‐random arrangement are preserved in the interface distribution function (IDF), if only the crystals are shielded by some transition layer. In a condensed random nanostructure, almost only next neighbor correlations are present. The distribution of the widths of amorphous gaps between the crystals, ha, is a truncated exponential distribution. In the scattering pattern the stochastic nanostructure can hardly be distinguished from a system with short‐range order. On the other hand, in the IDF the features of order become clear. In random systems there is no convolution polynomial based on crystalline and amorphous distributions. Only two shifted images of ha are occurring. We find that packing correlations collapse, if the crystallite thickness distribution is wide enough. In this case the pure particle scattering is a fair approximation in the IDF. This criterion is, in general, valid for technical polymer materials.IDFs computed from the nanostructure obtained in a computer simulation of ideal random isothermal crystallization after infinite time (random car parking process). Bold line: No transition zone. Thin line: Transition zone introduced ($\mathop {\bar p}\nolimits_t /\mathop {\bar p}\nolimits_c = \mathop {\bar t}\nolimits_t /\mathop {\bar t}\nolimits_c = 0.2$). Dashed‐dotted line: A Gaussian crystalline layer thickness distribution with a standard deviation of σt = 0.2.magnified imageIDFs computed from the nanostructure obtained in a computer simulation of ideal random isothermal crystallization after infinite time (random car parking process). Bold line: No transition zone. Thin line: Transition zone introduced ($\mathop {\bar p}\nolimits_t /\mathop {\bar p}\nolimits_c = \mathop {\bar t}\nolimits_t /\mathop {\bar t}\nolimits_c = 0.2$). Dashed‐dotted line: A Gaussian crystalline layer thickness distribution with a standard deviation of σt = 0.2.