Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators, due to their compactness and their convenient shape for tuning and coupling, are very attractive for low-beta beam acceleration. In this paper, two types of cavities with different geometry have been numerically simulated: the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz, beta=0.06 beams; then the relative electromagnetic parameters and geometric sizes have been compared. It is found that the second type, whose structural design is optimized with the conical stem and shaping drift-tube, can support the better accelerating performance. At the end of the paper, some structural deformation effects on frequency shifts and appropriate solutions have been discussed.

Preliminary study on melt-spinning, adhesion and adsorption properties of poly(lactic acid)

For the purpose of manufacturing cigarette filter tows and filter rods, the melt-spinning, adhesion and adsorption properties of poly(lactic acid) were studied. The rheological measurements were performed to examine the effects of various processing conditions on the melt flowability and spinnability, including those of residual moisture. The melt spinning and post-processings were followed by determining the molecular weight, thermal and mechanical properties of the fibers. The results obtained were useful to establishing the specification of the PLA resins for filter tows and filter rods manufacturing and to choosing proper melt-spinning and post-processing technologies.

Preliminary research on microporous membrane from F2.4 for membrane distillation

An asymmetric hydrophobic microporous membrane from the copolymer of tetrafluoroethylene and vinyliden fluoride (F2.4) has been fabricated by phase inversion process. Some characteristics, such as mechanical properties and hydrophobicity, have been examined and compared with polyvinylidenefluoride (PVDF) membrane. Experimental data exhibit F2.4 membrane excellent mechanical properties and hydrophobicity. F2.4 microporous membrane was approximately 6-8 times as high as PVDF membrane in stretching strain and extension ratio at break, and contact angle to distilled water of the fore (88.5degrees) was larger than the latter (80.0degrees), too. The results from membrane distillation (MD) process were well agreed with the fundamental laws of membrane distillation.

Preliminary study on the charge transfer and bond ionicity of binary crystals

Charge transfer and bond ionicity of some monovalent, divalent, and trivalent binary crystals of A(N)B(8-N) type have been investigated using the self-consistent method. The method divides the binary crystal systems into two subsystems which contain only one kind of element each in physical space. The charge transfer values are obtained by adjusting the charge in a self-consistent way. Based on the obtained charge transfer values, an empirical formula for bond ionicity has been proposed. It has been shown that the present results for bond ionicity are in good agreement with the previous theoretical study delivered by Levine and Pauling. The results also indicate that a large magnitude of charge transfer (or less excess charge in the bonding region) gives rise to high bond ionicity (or low bond covalency); this agrees well with the viewpoint that the excess charge in the bonding region is the origin of the formation of bond covalency. (C) 1998 American Institute of Physics. [S0021-9606(98)00837-X].

Preliminary investigations on polymerization catalysts composed of lanthanocene and methylaluminoxane

The polymerization of butadiene(Bd), isoprene(Ip) and styrene(St) has been examined using the six catalyst systems composed of lanthanocene, (C5H9Cp)(2)NdCl(I), (C5H9Cp)(2)SmCl(II), (MeCp)(2)SmOAr'(III), (Ind)(2)NdCl(IV), Me2Si(Ind)(2)NdCl(V) and (Flu)(2)NdCl(VI), and methylaluminoxane(MAO) respectively. All of them can be used to form the polyisoprene with molecular weights of 1 to 10 thousand and cis-1,4-unit contents of 41 to 47%. (I), (II) and (III) of them can be also used to form the polybutadiene with molecular weights of 10 to 20 thousand and cis-1,4-unit contents of 62 to 78%. In addition, the catalysts from (II) to (V) are still active for St polymerization and (II) of them gives a syndio -rich random polystyrene. It is noteworthy that (II) and (III) are active for homopolymerization of Bd, Ip and St in the same polymerization condition.

A preliminary study on chemistry of phenoxynaphthacenequinones

A preliminary study on the chemistry of 6-phenoxy-5,12-naphthacenesuinone derivatives was reported, It was found that the main product was 6-(N,N-dimethylamino)-5,12-naphthacenequinone when a reaction of 6-chloro-5,12-naphthacenequinone with 4-hydroxyazobenzenes in DMF was carried out under certain reaction conditions. When the reaction of 6-[4-(4-hydroxyphenyl)isopropyl)phenoxy]-5, 12-naphthacenequinone and epichlorohydrin was carried out in an acetone/DMF(V/V=2/1) mixed solvent and in the presence of K2CO3 and KI, a new phenoxynaphthacenequinone derivative,6,6'-[1-methylethylidenebis(4,1-phenyleneoxy)]bis(5,12-naphthacenequinone), was obtained.

A preliminary genetic map of Zhikong scallop (Chlamys farreri Jones et Preston 1904)

Zhikong scallop (Chlamys farreri Jones et Preston 1904) is one of the most important aquaculture species in China. The development of a genetic linkage map would provide a powerful tool for the genetic improvement of this species. Amplified fragment length polymorphism (AFLP) is a PCR-based technique that has proven to be powerful in genome fingerprinting and mapping, and population analysis. Genetic maps of C. farreri were constructed using AFLP markers and a full-sib family with 60 progeny. A total of 503 segregating AFLP markers were obtained, with 472 following the Mendelian segregation ratio of 1:1 and 31 markers showing significant (P< 0.05) segregation distortion. The male map contained 166 informative AFLP markers in 23 linkage groups covering 2468 cM. The average distance between markers was 14.9 cM. The female genetic map consisted of 198 markers in 25 linkage groups spanning 3130 cM with an average inter-marker spacing of 15.8 cM. DNA polymorphisms that segregated in a 3:1 ratio as well as the AFLP markers that were heterozygous in both parents were included to construct combined linkage genetic map. Five shared linkage groups, ranging from 61.1 to 162.5 cM, were identified between the male and female maps, covering 431 cM. Amplified fragment length polymorphism markers appeared to be evenly distributed within the linkage groups. Although preliminary, these maps provide a starting point for the mapping of the functional genes and quantitative trait loci in C. farreri.

Preliminary study on a potential antibacterial peptide derived from histone H2A in hemocytes of scallop Chlamys farreri

Histone H2A is reported to participate in host defense response through producing novel antimicrobial peptides (AMPs) from its N-terminus in vertebrates and invertebrates, while the AMPs derived from H2A have not to our knowledge been reported in mollusca. In the present study, gene cloning, mRNA expression of H2A from scallop Chlamys farreri, and the recombinant expression of its N-terminus were conducted to investigate whether a similar mechanism exists in mollusca. The full-length DNA of H2A was identified by the techniques of homology cloning and genomic DNA walking, The full-length DNA of the scallop H2A was 696 bp long, including a 5'-terminal untranslated region (UTR) of 90 bp, a 3'-terminal UTR of 228 bp with a stem-loop structure and a canonical polyadenylation signal sequence AATAAA, and an open reading frame of 375 bp encoding a polypeptide of 125 amino acids. The mRNA expression of H2A in the hemocytes of scallop challenged by microbe was measured by semi-quantitative RT-PCR. The expression of H2A was not upregulated after stimulation, suggesting that H2A did not participate in immunity response directly. The DNA fragment of 117 bp encoding 39 amino acids corresponding to the N-terminus of scallop H2A, which was homologous to buforin I in vertebrates, was cloned into Pichia pastoris GS115. The transformants (His(+) Mut(+)) containing multi-copy gene insertion were selected with increasing concentration of antibiotic G418. The peptide of 39 amino acids was expressed by induction of 0.5% methanol. The recombinant product exerted antibacterial activity against both Gram-positive (G(+)) and Gram-negative (G(-)) bacteria. The antibacterial activity toward G(+) bacteria was 2.5 times more than that against G(-) bacteria. The results elucidated that N-terminus of H2A was a potential AMP and provided a promising candidate for a new antibiotic screening. However, whether H2A is really involved in scallop immune response mechanisms needs to be further investigated. (C) 2006 Elsevier Ltd. All rights reserved.

PRELIMINARY STUDIES ON CRYOPRESERVATION OF SYDNEY ROCK OYSTER (SACCOSTREA GLOMERATA) LARVAE

In this study several parameters critical to the success of cryopreserving Sydney rock oyster (Saccostrea glomerata) larvae were investigated. They were: (1) cryoprotectants (10% dimethyl sulfoxide and 10% propylene glycol). (2) freezing protocols (with or without the seeding step). (3) larval concentrations (1,000, 3,000, 5,000, 10,000, 30,000 individuals mL(-1)). and (4) larval ages (6, 12, 24, 48 and 96 h old). The survival rates were determined as percentages of postthaw larvae performing active movements for the 6 and 12 h larvae or active cilia movement for the 24, 48 and 96 h larvae. Analyses showed that the difference in survival rates between different age classses was significant in all the experiments conducted, with the maximum survival rate being achieved in the 24-h-old larvae the postthaw survival rates of larvae cryopreserved with 10% dimethyl sulfoxide (93.1 +/- 0.2%) were significantly higher (P < 0.001) that those with 10% propylene glycol (81.5 +/- 0.4%). Differences in postthaw survival rates between different concentrations (1,000 30,000 individuals mL(-1)) were not significant within each of the three larval age classes (6-, 12-, and 24-h-old ) used.

Preliminary analysis of grain-size populations with environmentally sensitive terrigenous components in marginal sea setting

Terrigenous components were separated from the bulk sediment of Core A7 from the Okinawa Trough and Core A37 from the Ryukru Trench and grain-size distributions of these sub-samples were analyzed. Based upon an analysis of the grain-size data of the two sedimentary sequences, grain-size populations are identified to be sensitive to sedimentary environmental changes. The modal values and size ranges of the two main grain-size populations in Core A7 are evidently different from those of Core A37, indicating the spatial variability of sediment sources and transport processes between the two places. The downcore variations in the content of the environmentally sensitive grain-size populations reveal that during the accumulation of sedimentary material the environment remained relatively stable at the site where Core A7 was collected, except for the apparent events for the formation of two turbidite layers and a volcanic ash layer. However, the sedimentary sequence of Core A37 shows six sedimentary cycles, indicating a highly variable sedimentary environment at this location.