The formation of LC and other aromatic end-group structures in <Emphasis Type="Italic">O</Emphasis>-alkyl-substituted cellulose during kraft pulping conditions

Ultraviolet resonance Raman spectroscopy (UVRRS) was used to study the formation of aromatic and/or lignin-carbohydrate (LC) structures at the reducing end groups of O-alkyl-substituted cellulose under conditions simulating the initial phase of kraft pulping. The derivatives studied were methyl cellulose (MC) with degree of substitution (DS) of 1.64–1.95, carboxymethyl cellulose (CMC) with DS ∼0.6, and a lignin model compound, creosol. The total alkali concentrations in the treatments were 0.1 M and 0.5 M and the sulfidities were 1%, 10%, and 30%. HS⁻ ions and creosol are both strong nucleophiles and they compete for the hot-alkali-generated unsaturated electrophilic reaction sites in the reducing end groups of the polysaccharides. The results indicated that conditions similar to those in the initial phase of conventional kraft cooking (high OH⁻ and low HS⁻ ion concentrations) increased the aromatic nature of the end groups and conditions similar to those in the initial phase of super batch cooking (low OH⁻ and high HS⁻ ion concentrations) partly inhibited the formation of aromatic and LC end groups.     

光合细菌培养基配方的优化研究

光合细菌培养基的组分是由乙酸钠、氯化铵、磷酸二氢钾、硫酸镁、酵母膏等5种原料构成。采用L16(45)正交表,将5种原料作为光合细菌生长有影响的因素,通过试验数理统计的直观和理论分析,对其配方进行优化。试验结果表明,当培养基的配方为乙酸钠3.3 g/L、氯化铵0.6 g/L、磷酸二氢钾0.9 g/L、硫酸镁0.5 g/L、酵母膏1.5 g/L、光照3 000 lx和温度(32±2)℃时,培养72 h即可达到生长峰值,细菌总数可以从起初的1.75×109cfu/mL提高到3.19×109cfu/mL。优化的培养基条件能有效促进光合细菌生长。     

Diagnosis of bacterial kidney disease by detection of Renibacterium salmoninarum by real-time PCR

Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum (Rs), is a serious threat to salmon in aquaculture as well as to wild populations. We have developed a real-time polymerase chain reaction (PCR) for detection of Rs in kidney samples. The PCR is based on detection of unique parts of the 16S rRNA gene of Rs and DNA equivalent to 1-10 Rs genomes was detected per reaction. No cross-reactivity with other fish pathogenic or related bacteria could be demonstrated. Analysis of individual kidney samples collected from BKD classified populations identified 39.9% of the fish as positive by real-time PCR compared with 28.0% by polyclonal enzyme-linked immunosorbent assay (ELISA). The real-time PCR assay was found to be well suited for complementary use with ELISA for diagnosis of BKD, with the ability to detect clinical as well as covert Rs infections. The infection level determined by the polyclonal ELISA and by real-time PCR was significantly correlated.     

Genetic diversity of Flavobacterium psychrophilum recovered from commercially raised rainbow trout, Oncorhynchus mykiss (Walbaum), and spawning coho salmon, O. kisutch (Walbaum)

Flavobacterium psychrophilum is the aetiological agent of rainbow trout fry syndrome and bacterial cold water disease. This study examined the genetic diversity of F. psychrophilum isolates retrieved from multiple epizootics at rainbow trout, Oncorhynchus mykiss, rearing facilities and from spawning coho salmon, O. kisutch. A total of 139 isolates were confirmed as F. psychrophilum by PCR assay and were further typed using pulsed-field gel electrophoresis (PFGE). Multiple epizootics at three proximally located rainbow trout rearing facilities were numerically dominated by three PFGE profiles, which accounted for 76% of all trout isolates. In coho salmon, 19 PFGE profiles were differentiated by PFGE and four numerically dominant PFGE profiles represented 56% of all coho salmon isolates. PFGE analysis also indicated that the average similarity of macrorestriction patterns of F. psychrophilum isolates was greater in rainbow trout than in coho salmon (88% vs. 70%). Furthermore, it was not unusual to isolate multiple PFGE profiles from a single coho salmon sample whereas only two PFGE profiles were shared between two sample dates separated by 1 month. It is clear that the domestic rainbow trout aquaculture facilities studied here were primarily affected by a complex of genetically related strains whereas spawning coho salmon supported a much more genetically diverse collection of F. psychrophilum.     

网箱养殖鮸状黄姑鱼常见病害的防治

本文报道(鱼免)状黄姑鱼网箱养殖中常见病害及其防治方法。细菌性烂鳃病:流行季节为5—8月,危害各生长阶段鱼,川浓度10×10~(-6)漂白粉和10—20×10~(-6)呋喃西林分别浸洗3—5min,连续2、3次可治愈;细菌性竖鳞病:发病季节为4—12月,危害各生长阶段鱼,治疗用40×10~(-6)高锰酸钾浸洗5—10min及呋喃西林粉末涂抹患处,或注射链霉素15—20mg/kg鱼;肠炎病:发病水温18—30.5C,流行高峰25—30C,危害各生长阶段鱼,防治方法为,每100kg鱼用呋喃唑酮3—5g或氟哌酸5—10g拌饵投喂,连用4—6d;湖蛭病:流行于12—5月水温22C以下吋,寄生于各龄鱼,影响亲鱼的性腺发育,可用捕捉去除、淡水浸泡5—10min或5—6％盐水浸泡3—5min使虫体脱落;气泡病:发病季节5—9月,水温25—30.5C,危害体长150mm以下幼龟,将发病早期的个体移入水温较低、水质较清洁新鲜的水中,可使恢复正常。     

判定三相变压器联结标号的几种方法

在变压器并联运行的诸条件中，必须严格保证的条件是各变压器应属于相同的联结标号。本文介绍了三种判定变压器绕组联结组标号的方法，并通过实例加以说明。     

Food habits of fishes in the mangrove estuary of Urauchi River,Iriomote Island,southern Japan

The food habits of 67 fish species collected from the mangrove estuary of the Urauchi River, Iriomote Island, southern Japan were investigated using gut content analysis. Ontogenetic changes in food preference were recognized in nine species, including mugilids, gerreids, mullids, gobiids and tetraodontids. In most cases, juveniles of these species fed mostly on small crustaceans (e.g. calanoid and cyclopoid copepods and gammaridean amphipods) or detritus. With their subsequent growth, larger prey items (e.g. crabs and polychaetes) became dominant. A cluster analysis based on dietary overlaps showed that the mangrove fish assemblage comprised eight trophic groups (zooplankton, small benthic crustacean, large benthic crustacean, polychaete, fish, detritus, plant and insect feeders). Of these, large and small benthic crustacean feeders, which consumed mainly crabs and gammaridean amphipods, respectively, were the most abundantly represented in terms of species, whereas polychaete and insect feeders were each represented by only two species.     

SPSS软件在肥效试验数据分析中的应用

利用统计软件SPSS，对肥效试验的数据进行随机区组设计分析、裂区区组设计分析，应用该软件能使较为繁琐的统计过程变为更简单、直接、准确。