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- Adcox, K, et al.
(author)
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Construction and performance of the PHENIX pad chambers
- 2003
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In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 497:2-3, s. 263-293
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Journal article (peer-reviewed)abstract
- We present the Pad Chamber detector system in the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The three station system provides space points along each track in the spectrometer arms at mid-rapidity and covers a total area of 88 m(2). Its main functions are to provide the track coordinate along the beam and to ensure reliable pattern recognition at very high particle multiplicity. A new concept for two dimensional wire chamber readout via its finely segmented cathode was developed. The full readout system, comprising 172 800 electronic channels, is described together with the challenging design of the chambers. The electronics, mounted on the outer chamber face, together with the chamber itself amounts to 1.2% of a radiation length. Results from cosmic ray tests, showing an average efficiency better than 99.5% for all chambers are presented. The experiences from the full scale operation in the first run are reported. (C) 2002 Elsevier Science B.V. All rights reserved.
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- Zhang, L. N., et al.
(author)
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Solution properties of antitumor sulfated derivative of alpha-(1 -> 3)-D-glucan from Ganoderma lucidum
- 2000
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In: Bioscience, biotechnology and biochemistry. - : Oxford University Press (OUP). - 0916-8451 .- 1347-6947. ; 64:10, s. 2172-2178
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Journal article (peer-reviewed)abstract
- Four fractions of a water-insoluble alpha-(1-->3)-D-glucan GL extracted from fruiting bodies of Ganoderma lucidum were dissolved in 0.25 M LiCl/DMsO, and then reacted with sulfur trioxide-pyridine complex at 80 degreesC to synthesize a series of water-soluble sulfated derivatives S-GL. The degree of substitution of DS was measured by using IR infrared spectra, elemental analysis, and C-13 NMR to be 1.2-1.6 in the non-selective sulfation. Weight-average molecular weight M, and intrinsic viscosity [eta] of the sulfated derivatives S-GL were measured by multi-angle laser light scattering and viscometry. The M-w value (2.4 x 10(4)) of sulfated glucan S-GL-1 was much lower than that (44.5 x 10(4)) of original alpha-(1-->3)-D-glucan GL-1. The Mark-Houwink equation and average value of characteristic ratio C-infinity for the S-GL in 0.2 M NaCl aqueous solution at 25 degreesC were found to be: [eta] =1.32 x 10(-3) M-w(1.06) (cm(3) g(-1)) and 16, respectively, in the M-w range from 1.1 x 10(4) to 2.4 x 10(4). It indicated that the sulfated derivatives of the alpha-(1-->3)-D-glucan in the aqueous solution behave as an expanded chain, owing to intramolecular hydrogen bonding or interaction between charge groups. Interestingly, two sulfated derivatives synthesized from the alpha-(1-->3)-D-glucan and curdlan, a beta-(1-->3)-D-glucan, all had significant higher antitumor activity against Ehrlich ascites carcinoma (EAC) than the originals. The effect of expanded chains of the sulfated glucan in the aqueous solution on the improvement of the antitumor activity could not be negligible.
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- Zhang, L. N., et al.
(author)
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Triple helix of beta-D-glucan from Lentinus Edodes in 0.5 M NaCl aqueous solution characterized by light scattering
- 2001
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In: Polymer journal. - : Springer Science and Business Media LLC. - 0032-3896 .- 1349-0540. ; 33:4, s. 317-321
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Journal article (peer-reviewed)abstract
- beta-(1 -->3)-D-glucan with (1 -->6) branching (L-FV-I) from Lentinus edodes in water was degraded into seven fractions of different molecular weights by ultrasonic irradiation. Weight-average molecular weight M,, radius of gyration (1/2)(5) and intrinsic viscosity [eta] of the beta -D-glucan and its fractions in 0.5 M NaCl aqueous solution and dimethylsulfoxide (DMSO) were studied by multi-angle laser light scattering (MALLS), GPC combined with MALLS, and viscometry. M, dependence of [eta] for the glucan in 0.5 M NaCl aqueous solution was represented approximately by [eta] =7.69 x 10(-6) M-w(1.32) (cm(3) g(-1)) at M-w from 1.87 X 10(5) to 1.20 X 10(6) at 25 degreesC. GPC chromatograms of the glucans in aqueous solution contained two peaks, a main peak corresponding to triple-stranded chains with molecular weight M-w,M-m, and small second peak corresponding to fragments of single chains with M-w,M-s (about 20 +/-5% content). Analysis of M-w,M-m and (1/2)(z,m) in term of the known theory for wormlike chains yielded 2180 +/- 100 nm(-1), 120 +/- 10 nm and 0.31 nm for molar mass per unit contour length M-L, persistence length q, and contour length h per main-chain glucose residue, respectively, which agree closely with theory data of triple-helical chains and reported parameters for triple-helix schizophyllan in 0.01 M NaOH aqueous solution. The ratios of M-w,M-m, in 0.5 M NaCl to M, in DMSO were calculated to be roughly 3. The predominant species of the glucan in 0.5 M NaCl aqueous solution exist as triple-helical chains with high rigidity, and in DMSO as single-flexible chains.
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- Zhou, Qi, et al.
(author)
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Phase transition of thermosensitive amphiphilic cellulose esters bearing olig(oxyethylene)s
- 2000
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In: Polymer Bulletin. - : Springer Science and Business Media LLC. - 0170-0839 .- 1436-2449. ; 45:05-apr, s. 381-388
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Journal article (peer-reviewed)abstract
- A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellulose with corresponding monofunctional acid chloride in a 10% LiCl-dimethyl acetoamide (DMAc) solution. The effect of total DS value on the solubility of the derivatives in aqueous solution was investigated. It was found that the lower limit DS value for both water-soluble and amphiphilic derivatives decreases with increasing length of oxyethylene chains. The amphiphilic derivatives, which are soluble in both water and chloroform, precipitate out of aqueous solution on heating without gel forming, such a phase transition behavior was studied in terms of DS value, length of oxyethylene and concentration. The precipitation temperature (T-p) of the amphiphilic derivatives is range from 54 degreesC to 96 degreesC. It decreases with increasing the total DS value, and increases with an increase in the length of oxyethylene chains. The T-p value of the derivatives was found to be almost independent in the concentration range of 1-15 wt %, however the T-p value increases sharply with decreasing polymer concentration when the concentration is lower than 1 wt%.
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- Zhou, Qi, et al.
(author)
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Synthesis and properties of O-2- 2-(2-methoxyethoxy) ethoxy acetyl cellulose
- 2001
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In: Journal of Polymer Science Part A. - 0887-624X .- 1099-0518. ; 39:3, s. 376-382
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Journal article (peer-reviewed)abstract
- In this article, a series of O-2-[2-(2-methoxyethoxy)ethoxy] acetyl celluloses with different degree of substitution (DS) values was synthesized by a homogeneous reaction of cellulose with 2-[2-(2-methoxyethoxy)ethoxy] acetyl chloride in a 10% (w/w) dimethylacetamide/lithium chloride solution, combined with pyridine as the acid acceptor. The total DS values of the derivatives in anhydroglucose units was determined by H-1 and C-13 NMR spectra, and ranged from 0.4 to 3.0, depending on the amount of acid chloride in the reaction. The effects of the total DS values and the O-2-[2-(2-methoxyethoxy)ethoxy]acetyl acetyl substituent distribution on the solubility of the derivatives were investigated. The lowest limit of the DS value for water-soluble 0-2-[2-(2methoxyethoxy)ethoxy]acetyl cellulose was approximately 0.5, which is lower than that of methylcellulose. The amphiphilic derivatives with higher DS values than 1.7 exhibited a good solubility in both water and organic solvents, such as dimethyl sulfoxide, tetrahydrofuran, and chloroform. Sol-gel transition in aqueous solution was observed for the amphiphilic derivatives with a higher DS value than 1.7; the precipitation temperature (T-p) decreased as the DS value increased, showing that the derivatives are highly temperature sensitive. The thermal properties of the fully substituted derivative were measured using polarized microscopy, DSC, and X-ray diffraction; and are dis cussed in terms of phase transition of the sample derivatives.
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