建筑用竹结构的强度和弹性

印度南部特别是卡纳塔卡利用小刺竹建造房屋。本文对刺竹的强度和弹性进行了调查,并研究了竹构件的压缩强度、抗折性和振动性进行试验,从而得到弹性摸量。竹构件的压缩强度在31 Mpa到47 Mpa之间,弹性摸量在20 000 Mpa~40 000 Mpa之间,通过抗折性和振动性实验,得出压缩弹性摸量低于拉力摸量的结论。剪应强度在4 Mpa~11 Mpa之间。当应变力为0.6%时,小刺竹的抗折强度为60 Mpa。竹子的平均压力低于10 Mpa。     

Differential toxicity of Bacillus thuringiensis strains and their crystal toxins against high-altitude Himalayan populations of diamondback moth, Plutella xylostella L

BACKGROUND: Diamondback moth, Plutella xylostella (L.), is a major insect pest of crucifers in the biodiversity‐rich north‐western Indian Himalayan hills. The present investigation was aimed at determining the susceptibility pattern of P. xylostella populations collected from different locations of this region to autochthonous and standard Bacillus thuringiensis strains. RESULTS: Among the reference as well as indigenous B. thuringiensis strains tested, sub spp. kurstaki HD‐1, kurstaki HD‐73, galleriae HD‐8, local galleriae/colmeri strain BtOa1 and some of their Cry1 class toxins were found to be highly toxic. Surprisingly, the sub sp. tolworthi HD‐125, local tolworthi strain BtHa1 and Cry9 class toxins were found to be non‐toxic. Midgut homogenate from fourth‐instar larvae was found to activate 130 kDa protoxin from the local tolworthi strain BtHa1 into 68 kDa toxin, but failed to exert any larval mortality, probably owing to lack of receptor binding. CONCLUSION: The present study provides valuable baseline susceptibility data for the deployment of B. thuringiensis‐based control methods, as well as for future monitoring of development of resistance in P. xylostella to B. thuringiensis in this ecologically sensitive region. Copyright © 2008 Society of Chemical Industry     

Quantification of Inorganic Anions in Tea (Camellia Sinensis (L) O. Kuntze) Tissues and Soil Using Ion Chromatography Coupled with Conductivity Detector

A simple ion chromatographic method is proposed for the simultaneous quantification of five inorganic anions in samples derived from tea system with a suppressed conductivity detector. For this purpose extracts of leaves, roots and soils of tea obtained at room temperature yielded chromatographic profiles with substantial differences in the relative contents of fluoride (F^?), chloride (Cl^?), nitrate (NO₃^?) and sulfate (SO₄ ^2-). Although Cl^? and SO₄^2- were common to each extracted sample in different categories and accounted for the majority of the anions present, one additional anion peak was detected in root and leaf tissues. Irrespective of the clone and sample investigated the average F^? content varied from 253 to 1664 mg kg^?1, Cl^? varied between 60 and 1789 mg kg^?1, NO₃^? varied from 119 to 188 mg kg^?1 and SO₄^2- varied between 55 and 6779 mg kg^?1. The anionic load was at its crest in clone UPASI – 3 in all the three categories of samples with few exceptions. Among the samples investigated, tea roots contained a considerable amount of major anions, while tea soils had the lowest amount of the detected anions. The recovery of all the quantified anions was above 95%. The correlation coefficient for all anions where above 99.50%. The concentration of nitrite (NO₂^?) was below the limits of detection based on the analytical technique adopted. Anion nitrate was not detected in tea root and tea leaf extracts.     

Current status,opportunities, and challenges of cover cropping for sustainable dryland farming in the Southern Great Plains

Cropping systems that integrate cover crops into crop rotations, reduce tillage intensity and frequency, and maintain residue cover have the potential to improve agricultural sustainability in drylands. However, there is much yet to learn about the benefits of cover crops in sustainable dryland farming in the southern Great Plains (SGP). We reviewed the literature on the effects of cover crops on soil organic carbon (SOC), nitrogen, soil water conservation, and crop yields in dryland cropping systems of the US Great Plains (GP), and analyzed the opportunities and challenges for integrating cover crops into dryland crop-fallow systems of the SGP. Majority of the studies in the central Great Plains (CGP) and the northern Great Plains (NGP) of the United States suggest that cover cropping improves sustainability of cropping systems through their positive effects on SOC accumulation, nutrient cycling, soil erosion control, weed suppression, and soil health improvement. However, integrating cover crops into dryland cropping systems of the SGP faces challenges because of low quantity of soil-water availability. More research on the tradeoff between water use and other agroecosystem benefits of cover cropping is required to successfully integrate cover crops into dryland cropping systems in the SGP.     

Arbuscular Mycorrhizal （AM） Diversity in Prosopis cineraria （L.） Druce Under Arid Agroecosystems

Arbuscular mycorrhizal （AM） fungi associated with Prosopis cineraria （Khejri） were assessed for their qualitative and quantitative distribution from eight districts of Rajasthan. A total of three species of Acaulospora, one species of Entrophospora, two species of Gigaspora, twenty-one species of Glomus, seven species of Sclerocystis and three species of Scutellospora were recorded. A high diversity of AM fungi was observed and it varied at different study sites. Among these six genera, Glomus occurred most frequently. Glomus fasciculatum, Glomus aggregatum, and Glomus mosseae were found to be the most predominant AM fungi in infecting Prosopis cineraria. Acaulospora, G. fasciculatum, Sclerocystis was found in all the fields studied, while Scutellospora species were found only in few sites. A maximum of thirty-six AM fungal species were isolated and identified from Jodhpur, whereas only thirteen species were found from Jaisalmer. Spores of Glomusfasciculatum were found to be most abundant under Prosopis cineraria.     

First record of Asian grey weevil (<Emphasis Type="Italic">Myllocerus undatus)</Emphasis> on coconut from Kerala,India

The occurrence of Asian grey weevil Myllocerus undatus (Curculionidae: Coleoptera) damaging coconut (Cocos nucifera L.) seedlings is reported for the first time from Kerala, India. A mild to moderate level of infestation damaging 5–10% leaf lamina of un-split leaves with a typical notching-like symptom along the leaf margins is noticed on the majority of the coconut seedlings belonging to different coconut varieties, viz., ‘Chowghat Orange Dwarf’, ‘Chowghat Green Dwarf’, ‘Malayan Green Dwarf’, ‘West Coast Tall’ and Dwarf x Tall hybrids. M. undatus has not been reported as a destructive pest on any of the crops from India and is considered to be a pest of quarantine significance. Adult weevils have a characteristic tri-spined hind femur and elytra strongly angled broader than the prothorax.     

Immunization against bovine tropical theileriosis, using 60Co-irradiated infective particles of Theileria annulata (Dschunkowsky and Luhs 1904) derived from ticks.

Portions of ground supernate material from Theileria annulata-infected and prefed adults of the Hyalomma anatolicum anatolicum were irridiated by 60Co source at 0, 3, 5, 6, 7, or 9 krads. These portions were injected subcutaneously into different groups of cross-bred calves. The calves injected with 0-, 3-, or 5-krad irradiated tick supernate had severe reactions (rectal temperature 39.8 to 41.6 C, two- to fourfold enlargement of prescapular lymph gland, mean peak parasitemia 27.3% to 32.5% infected erythrocytes, decreased PCV 41.7% to 60.7%, and hemoglobin concentration 37.5% to 50.8%), and many died, whereas those injected with 6- or 7-krad irradiated tick supernate had minimal reactions (rectal temperature 39.2 to 39.8 C, slight enlargement of prescapular lymph gland, parasitemia less than 1%, decrease packed cell volume 15.1%, and hemoglobin concentration 20.1%), with no mortality. All surviving calves injected with nonirradiated (0-) or 3-, 5-, 6-, or 7-krad irradiated tick supernate developed comparable indirect fluorescent antibody titers and were resistant to challenge exposure with infective material from 30 ticks. The calves injected with 9-krad irradiated tick supernate showed no reactions and did not develop indirect fluorescent antibody titers; they were also susceptible to challenge exposure with infective tick material.     

Evaluation of the cell-mediated immune response in cattle induced by 2,4-dinitrochlorobenzene

A technique has been evolved and standardized for evaluating the cell-mediated immune (CMI) response in cattle induced by 2,4-dinitrochlorobenzene (DNCB). Six healthy cross-bred Jersey cows were used. The dose and the number of applications for primary sensitization and the challenge dose after the 14th day have been standardized. The gross and histological pictures of the CMI response shown by these cattle are described in detail and their usefulness in assessing the CMI response in various disease conditions including tumour is indicated.     

To Insure or not to Insure? Factors Affecting Acquisition of Prescribed Burning Insurance Coverage

Prescribed burning is a widely used tool in forest and grassland management. However, because fire that escapes from a prescribed burn accidentally may cause property damage, injuries, and even human casualties, purchasing insurance to cover such damages may be beneficial for prescribed burn practitioners. Given that insurance coverage for prescribed fire is recently emerging, factors that determine burners’ decisions to purchase such insurance are largely unknown. On the basis of data from a survey of prescribed burn practitioners in 14 southern and midwestern states, we modeled prescribed burners’ likelihood of purchasing insurance with respect to demographic characteristics, land management objectives, and importance placed on regulatory compliance and land use practices. Results suggest that prescribed burn practitioners are more likely to obtain such insurance if they are landowners themselves or have a written prescribed burn plan. Age of respondents and the level of importance they place on compliance with environmental laws also had a significant positive effect on the likelihood of obtaining insurance coverage. Respondents were less likely to purchase insurance if their land management objective was to control invasive plants or they considered the availability of lower-cost alternatives for woody plant removal an important factor in deciding whether or not to conduct prescribed burns. These findings shed light on underlying factors influencing insurance coverage for prescribed burning and are potentially beneficial for promoting the acquisition of insurance among burn practitioners.     

Restoration of the adipogenic gene expression by naringenin and naringin in 3T3-L1 adipocytes

BackgroundNaringenin and its glycoside naringin are well known citrus flavonoids with several therapeutic benefits. Although the anti-adipogenic effects of naringenin and naringin have been reported previously, the detailed mechanism underlying their anti-adipogenesis effects is poorly understood.ObjectivesThis study examined the anti-adipogenic effects of naringenin and naringin by determining differential gene expression patterns in these flavonoids-treated 3T3-L1 adipocytes.MethodsLipid accumulation and triglyceride (TG) content were determined by Oil red O staining and TG assay. Glucose uptake was measured using a 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose fluorescent d-glucose analog. The phosphorylation levels of AMP-activated protein kinase (AMPK) and acetyl Co-A carboxylase (ACC) were observed via Western blot analysis. Differential gene expressions in 3T3-L1 adipocytes were evaluated via RNA sequencing analysis.ResultsNaringenin and naringin inhibited both lipid accumulation and TG content, increased phosphorylation levels of both AMPK and ACC and decreased the expression level of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) in 3T3-L1 adipocytes. RNA sequencing analysis revealed that 32 up-regulated (> 2-fold) and 17 down-regulated (< 0.6-fold) genes related to lipid metabolism, including Acaca, Fasn, Scd1, Mogat1, Dgat, Lipin1, Cpt1a, and Lepr, were normalized to the control level in naringenin-treated adipocytes. In addition, 25 up-regulated (> 2-fold) and 25 down-regulated (< 0.6-fold) genes related to lipid metabolism, including Acaca, Fasn, Fabp5, Scd1, Srebf1, Hmgcs1, Cpt1c, Lepr, and Lrp1, were normalized to the control level by naringin.ConclusionsThe results indicate that naringenin and naringin have anti-adipogenic potentials that are achieved by normalizing the expression levels of lipid metabolism-related genes that were perturbed in differentiated 3T3-L1 cells.