On a wave dissipation method for offshore aquaculture areas

This paper describes a proposed flexible floating structure to provide a method of wave dissipation for an aquaculture area. The structure is mainly made of net-tubes which are filled with floating balls. A number of ways of placement for the flexible structure have been investigated in hydraulic model studies and the results are presented in this paper. From these studies it is concluded that if a certain number of rows of these floating structures are connected with proper spacings, then the complex floating structure will serve as a good wave sheltering system for an offshore aquaculture area.     

松苗立枯病的研究Ⅰ、分布损失、征状类型、病原、和栽培影响

松苗立枯病是东北地区针叶树育苗上的重要问题,其中以落叶松、樟子松、和红松等幼苗发病较重,油松和赤松等幼苗发病为轻。幼苗发病征状有土内腐死、猝倒、立枯、地上腐烂、和一、二年生大苗发生枯萎落叶等五个类型。诱致松苗发生侵染性立枯病的病菌,有 Rhizoctonia、Pythium 和 Fusarium等三种菌类,其中 Rhizoctonia 尤为主要。松苗立枯病发生的轻重与育苗措施有密切关系,地势低洼或位于山脚下坡的苗圃或苗床,一般发病较重。种子经雪藏混砂催芽处理后,能提早种子萌芽、出土和齐苗,有降低发病程度的作用。光照多少对幼苗发病有影响。根据苗圃的调查观察,全光育苗发病率低,遮蔭育苗发病率高;但在沈阳试验结果还不能证实这一点,相反的半遮蔭育苗要好些。     

广州地区豌豆黄顶病和武汉地区蚕豆黄顶病的病原病毒初步鉴定

广州地区豌豆黃顶病每年在11月开始发生,发病率一般很低,但个別田块可达50％以上。病株頂部叶片黄化,縮小,皺縮卷曲,叶质脆,植株矮縮,不开花結莢,最后发生丛枝現象,植株很快枯死。武汉地区蚕豆黄頂病每年在苗期(11月)开始发生,发病率約1—5％,翌年4、5月流行,发病率輕的为5—10％,重的达80—100％。症状和广州地区的豌豆黄頂病基本相同。     

Radial growth of <Emphasis Type="Italic">Cinnamomum kanehirae</Emphasis> Hayata displays a larger temperature sensitivity in dominant than codominant trees

Key message

The radial wood growth curves of Cinnamomum kanehirae Hayata (an endangered species of subtropical Taiwan) exhibit an S shape. The dominant trees displayed a larger radial growth than the codominant trees, and their growth was more sensitive to air temperature.

Context

Knowledge of wood radial growth is important for evaluating the factors that limit tree growth performance. The relevant experiments have mostly been conducted in cold and temperate ecosystems, but rarely in subtropical ecosystems.

Aims

In this study, we aimed to construct a unified radial growth model for Cinnamomum kanehirae Hayata and to identify its sensitivity to temperature.

Methods

The wood radial increments were quantified for 3 years by either pinning or microcoring. The radial wood growth curves were modelled integratively by semiparametric regression and individually by curve fitting. The effects of tree social class, interannual and environmental factors on radial growth were analysed quantitatively.

Results

A unified S-shaped growth model for C. kanehirae was successfully constructed. By including the social class effect, the model was significantly improved. The maximum radial increment (A) was significantly correlated with the maximum growth rate (μ); both A and μ were significantly higher in dominant than in codominant trees. The time-varying radial growth rate was more sensitive to air temperature in dominant than in codominant trees.

Conclusion

Semiparametric models revealed an S-shaped growth curve of C. kanehirae and confirmed the higher temperature sensitivity of dominant trees compared to codominant trees in humid subtropical areas.

     

张北县农业可持续发展对策研究

通过对张北县土地利用现状的调研与评价及其农业中存在问题的分析,提出了该地区农业可持续发展的对策,对促进土地综合整治、农业结构调整与优化以及国民经济持续发展具有重要的现实意义。     

Application and determination of organic polymers

In water and waste treatment, cationic polyelectrolytes can function as either primary coagulant or coagulant aid because they are positively charged. It has been known that most of the colloidal and suspended impurities in natural water have negative surface charges. Cationic polyelectrolyte will neutralize the impurities or pollutants, then agglomerate them into larger masses for rapid solid-water separation by sedimentation, flotation, centrifugation, filtration, or reverse osmosis. Anionic polyelectrolyte are negatively charged and function as coagulants in water and waste treatment. They must be applied along with positively charged coagulants which neutralizes the negative charge on the colloidal and suspended impurities. In a water softening process, where precipitation particles are positively charged, however, anionic polyelectrolytes alone can coagulate. Nonionic organic polymers, however, can only function as coagulant aids which should be introduced at a point shortly after flocculation first occurs. Nonionic polymers will coat the existing floc particles so that when the flocs collide, they will adhere to one another, thus forming larger and heavier masses. This paper initially describes the various applications of organic polymers in the fields of environmental, chemical and biomedical engineering. Subsequently a new technique for the accurate, quantitative determination of polyelectrolytes in the 0.00002 N to 0.005 N concentration range is introduced. The principles, apparatus, reagents, and analytical procedures of the method are presented in detail. The test procedure developed can also measure the net charges of colloidal substances, this can be used for chemical coagulation process control.     

Effects of artificial supplemental light on the reproductive season of geese kept in open houses

1. New lighting programmes were designed to change the pattern of goose reproduction, based on the response of predictable avian photoperiodic stimulation. The objective of this study was to evaluate the efficiency of a long photoperiod of 20L on shifting goose reproduction to the non-breeding season in an open housing system. 2. Eighty mature White Roman geese were randomly allocated into 4 groups (male:female = 1:4). The supplemental lighting programmes with a daily photoperiod of 20 h were initiated on 22 November and withdrawn when 90% of geese were moulting in the treatment groups. Artificial light intensities of 220, 120 and 20 lux were provided to experimental groups A, B and C, respectively. In contrast, the geese in control group D were kept under natural lighting conditions throughout this study. 3. The annual reproductive curves of all the experimental groups consisted of two separate laying periods. The first period was induced by the supplemental lighting programme while the second was induced by the naturally increasing photoperiod in this subtropical region. The first laying period of the experimental groups occurred in the breeding season, and the second was relocated to the non-breeding season. 4. The supplemental lighting could shift the laying periods of geese to the non-breeding season and had no significant effect on annual reproductive performance. The supplemental light programmes described here were able to manipulate the reproductive season of geese reared in open houses, which would be of practical value.     

凉城县土地利用现状分析和可持续利用研究

本文利用遥感和GIS技术,对凉城县2000年和20世纪80年代末的两期TM影 像,进行解译、数字化、建库及统计分析,较详细地分析了土地利用现状、土地利用近十年动态 变化,进一步探讨了土地利用动态变化的驱动因子以及土地利用中存在的问题,最后提出了土 地可持续利用的对策和建议。     

Characterization of the dimer-monomer equilibrium of the papaya Copper/Zinc superoxide dismutase and its equilibrium shift by a single amino acid mutation.

The coding region of the copper/zinc superoxide dismutase (Cu/Zn SOD) cDNA from papaya fruit, Carica papaya L. cv. Tainong 2, was cloned into an expression vector, pET-20b(+). The Cu/Zn SOD was expressed in Escherichia coli and purified by His-tag technique. Two active forms of the enzyme (30% dimer and 70% monomer) in equilibrium were observed. The activity of the dimeric enzyme was higher than that of the monomeric form. The thermal inactivation rate constant K(d) values calculated for the dimer and monomer at 90 degrees C were -0.0203 and -0.0216 min(-1), and the half-lives for inactivation were 41.9 and 31.8 min, respectively. This indicated that the dimeric enzyme was more stable than its monomeric form. The dimerization of the enzyme was inhibited under acidic pH (below 3.0) or imidazole buffer (above 0.5 M), whereas it was not affected under alkaline pH (above 9.0). Both activity and forms of the enzyme were not affected by 1-4% SDS. Furthermore, the dimeric enzyme was much more resistant to proteolytic attack after 3 h of incubation at 37 degrees C with trypsin or chymotrypsin. In addition, mutation of the papaya Cu/Zn SOD at position 48 from Leu to Phe (L48F) affected the association of monomer, whereas a mutant with Lys substitution (L48K) at the same position tended to dissociate into monomeric form.     

Dual role of esterases in insecticide resistance in the green rice leafhopper

The role of esterases as related to insecticide resistance was studied in an organophosphorus (OP)-resistant strain of the green rice leafhopper. As judged by p-nitrophenyl acetate hydrolysis, 21, 5, and 74% of the esterase activity was located in nuclei/mitochondria, microsomes, and the soluble fraction, respectively. All the fractions were active in hydrolyzing malathion, paraoxon, and fenvalerate. Hydrolysis of malathion and fenvalerate increased with time while that of paraoxon reached a plateau within 15 min. Since a considerable amount of p-nitrophenol was detected in the paraoxon reaction at 0°C and at zero time, the formation of p-nitrophenol may be due to phosphorylation of the esterases rather than phosphorotriesterase action. The results suggest a dual role for esterases in resistance mechanisms; a catalyst for hydrolysis of malathion and fenvalerate, and a binding protein for the oxygen analogs of other OP insecticides, both of which would protect the intrinsic target, acetylcholinesterase, from inhibition. Chromatofocusing of the soluble fraction resolved five esterase peaks, I–V. These esterases were active toward the three general substrates as well as for the three insecticides tested, except for Peak I in which the overall activity was too low. Thin-layer agar gel electrophoresis showed that the chromatofocusing peaks I–V corresponded to the electrophoretic bands E₁–E₅, some of which were previously shown to be associated with OP resistance. The dual role of these esterases may explain the cross-resistance between malathion and other OP insecticides as well as synergism between OP and carbamate insecticides.