Properties of metallic nanowires: from conductance quantization to localization

Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2).     

黄政德教授运用甘麦大枣汤治疗失眠临床经验

失眠属于中医学“不寐”的范畴,黄政德教授运用经方理论,灵活运用甘麦大枣汤治疗失眠。黄老师认为甘麦大枣汤所治失眠的重要病症特点是睡眠易惊醒,临床对于中医辨证属于心肝阴血不足、虚阳偏亢、扰动心神的顽固性失眠患者疗效较好。     

黄政德教授从“肺合大肠”理论治疗咳嗽经验

“五脏六腑皆令人咳,非独肺也”,黄政德教授以中医辨证理论为指导,基于肺与大肠理论来治疗咳嗽,其疗效突出,对于临床治疗咳嗽具有深远的指导意义。     

Cytokinin induces bacterial pathogen resistance in tomato

Phytohormones are involved in the regulation of plant responses to biotic stress. How a limited number of hormones differentially regulate defence responses and influence the outcome of plant–biotic interactions is not fully understood. In recent years, cytokinin (CK) was shown to induce plant resistance against several pathogens. In the present study, we investigated the effect of CK in inducing tomato resistance against the hemibiotrophic pathogenic bacteria Xanthomonas campestris pv. vesicatoria (Xcv) and Pseudomonas syringae pv. tomato (Pst). We demonstrate that CK enhances tomato resistance to Xcv and Pst through a process that relies on salicylic acid and ethylene signalling. CK did not directly affect the growth or biofilm formation ability of these pathogens in vitro. Overall, our work provides insight into the underlying mechanisms of CK-induced immune responses against bacterial pathogens in tomato.     

Argentinian potato leafroll virus P0 protein: Novel activities for a previously known suppressor

The potato leafroll virus (PLRV) P0 protein (P0^PL) is a suppressor of RNA silencing. In this study, we showed that P0 protein from an Argentinian isolate of PLRV (P0^PL-Ar) has an additional activity not described for other PLRV or P0 proteins from poleroviruses. Besides reporting that P0^PL-Ar displays both local and systemic silencing suppressor activity, we demonstrated, for the first time, that P0^PL-Ar impedes accumulation of dsRNA-derived siRNAs. We also showed that P0^PL-Ar interacts with Solanum tuberosum SKP1 orthologue (StSKP1) and triggers destabilization of ARGONAUTE 1 (AGO1) and that these actions are mediated by the F-box-like domain. A mutant in the GW/WG motif within the P0^PL-Ar F-box-like motif lost the suppression activity, the interaction with StSKP1 and abolished AGO1 decay. Interestingly, a mutant in the L76/P77 residues within the P0^PL-Ar F-box-like motif, which lost the suppression activity and the interaction with StSKP1, retained the capacity to enable AGO1 decay. Thus, unlike other P0 proteins of previously characterized poleroviruses, P0^PL-Ar seems to have a dual activity, according to the findings of this study. This protein would act at both an upstream and a downstream step of the RNA silencing pathway: upstream of Dicer-like enzyme (DCL)-mediated primary siRNA production and downstream at the RNA-induced silencing complex (RISC) complex level. Our results contribute to the understanding of the different ways PLRV P0 proteins function as silencing suppressors.     

Effect of insecticides on the Colorado potato beetles resistant to OP, OC and P insecticides

Starting in 1996, a three year test program was conducted. In 56 laboratory trials, the resistance of the Colorado potato beetle (CPB) to OP, OC and P insecticides was proven in almost the whole of Croatia. In field trials, the stress was placed on testing the initial and residual efficacy on larvae, the effect of insecticides in preventing leaf damage and on establishing the relation between leaf damage and achieved yields. Imidacloprid showed a high initial and a very long residual efficacy, good leaf protection and high yields. Hexaflumuron had a slow initial but a very long residual action and ensured good leaf protection and high yields. Fipronil showed a good initial and residual action, good leaf protection and ensured high yields. Spinosad, thiamethoxam and lufenuron showed a satisfactory residual action, good leaf protection and high yields. Bensultap was highy efficient for only a short period but ensured low leaf damage and high yields. Thiocyclam was unsatisfactorily efficient. When total defoliation occurred at the begining of tuberization (1996) the yield was 8.8 times higher on protected than on unprotected plots. When total defoliation occurred shortly before the end of tuberization (1997) the yield was only 1.4 times higher on protected than on unprotected plots. When 75% defoliation occurred during an intensive tuberization process (in 1998 I) the yield on protected was 2.5 times higher than on unprotected plots, and when 25–40% defoliation occurred at the middle of the tuberization process (1998 II and III) the yields were 1.2 to 1.3 times higher on protected than on unprotected plots.     

Amending Soil with Sludge,Manure, Humic Acid,Orthophosphate and Phytic Acid: Effects on Infiltration,Runoff and Sediment Loss

Application of organic wastes to cultivated lands can replace mineral fertilizers but may also alter soil physical properties and enhance pollution potential. The objective of this study was to investigate the effects of biosolids [composted manure (MC) and activated sludge (AS)] and specific biosolid component [orthophosphate (OP), phytic acid (PA) and humic acid (HA)] application on soils differing in texture [loamy‐sand (Ramat‐HaKovesh, RH), loam (Gilat, GL) and clay (Bet‐Dagan, BD)], infiltration rate, runoff volume and soil sediment loss. The soils were packed in erosion boxes (400 × 200 × 40 mm) and subjected to six consecutive simulated rainstorms, each of 186 mm deionized water. The results showed that runoff volume and sediment loss from untreated soils increased with increasing clay contents. In treated soils, the response to AS application differed from the response to other amendments; in the BD clay and GL loam, it was the only amendment that caused a decrease in sediment removed by runoff. In the RH loamy‐sand, all amendments reduced the final infiltration rate, but only AS and HA increased the measured runoff. It is proposed that the difference in the response of the soils to the amendments is associated with the soil's ability to attenuate changes in the negative charge on the clay edges following the increase in the specific adsorption of charged anions, thus controlling clay swelling and maintaining aggregate integrity. The effects of amending soils with a source of organic matter in order to control runoff and soil erosion are not straight forward and depend on soil and amendment properties. Copyright © 2015 John Wiley & Sons, Ltd.     

Hormonal changes associated with ageing and induced moulting of domestic hens

1. The effect of age on ovarian function was studied in 245-, 350-, 500-, 700- and 800-d-old Lohmann hens. The effect of three different methods for moult induction on ovarian function and corticosterone concentration was studied in 500-d-old hens. 2. No significant reductions in ovarian weight or in number of follicles before the age of 700 d were found. The ability to produce progesterone and oestradiol-17beta was unchanged up to the age of 700 d and the circadian secretion of these two steroids was identical in young (225 d) and old hens (600 d). 3. The effects of induced moulting by feed withdrawal (FW) and a high Zn (HZn) diet on body weight and ovarian function were very similar; those of a moderate Zn with low Ca (MZn/LCa) diet were smaller. 4. The first significant effect of moulting was a decrease in oestradiol-17beta plasma concentration (d 2). Plasma progesterone decreased more gradually than oestradiol-17beta, and reached a nadir on d 6 in FW- and HZn-treated hens and on d 9 in MZn/LCa-treated ones. 5. Hens treated with either FW or the MZn/LCa, but not those with the HZn diet, showed a very sharp rise in corticosterone concentration on d 2 of treatment. Thus the MZn/LCa diet was less efficient than the other treatments in induction of ovarian involution, but had a similar effect on stress induction, as indicated by increases in plasma corticosterone.     

Use of a dynamic programming model to estimate the value of clinical mastitis treatment and prevention options utilized by dairy producers

This study discusses and demonstrates the construction and application of a specially structured dynamic programming replacement and insemination optimization and simulation model of the dairy cow that includes detailed representation of repeated episodes of clinical mastitis (CM). The application determined optimal individual cow decisions, which were then compared with mastitis culling rules of thumb to determine the deviation of these rules from optimality. Calculation of break-even values of applying a preventive measure to reduce CM incidence or severity in the form of two fictitious mastitis vaccines were also carried out. Model input parameters were based on data from five large dairy herds in New York State (about 16,000 lactations), but these parameters can be easily changed for other types of dairy operations. To demonstrate the usefulness of this model to assist individual cow CM treatment options, the cost of the decision to cull a third lactation cow, six months after calving, with the first case of CM, was negative $3 USD for a low milk producing open or pregnant cow (i.e. cull), and positive $850 USD for a high milk producing and pregnant cow (i.e. treat even with extremely high treatment cost). Compared with the model recommended optimal policy, a rule of thumb decision to routinely treat all cows with a first case of CM resulted in an additional cost of $2 per cow per year, a very low deviation from optimality and suggests all cows should be given a second chance. A policy of replacing all CM cows after their second CM case after treatment of the first CM incident resulted in an additional cost of $27 per cow per year. If the decision was to replace all cows only after their third CM case this cost estimate was $8. The cost-benefit of applying two fictitious vaccinations showed that a vaccination reducing the milk loss caused by Gram-negative CM by 50% had a break-even cost of $14 per cow per year. A vaccination that would result in additional reduction of the risk of CM by 50% had a break-even cost of $37 per cow per year.     

生草对新疆南部干旱区苹果园土壤肥力的影响

果园生草作为重要的果园土壤管理措施之一,对果树生长发育和土壤肥力都有重要影响。以新疆南部阿克苏地区成林苹果园为对象,研究生草和清耕2种果园土壤管理方式对苹果园土壤肥力变化的影响。测定结果表明,生草能提高0～30 cm土层土壤有机质含量,且以表层土壤增加更为显著。生草试验后各处理0~30 cm土层土壤速效养分值均较试验前有不同程度的提高,但土层中全氮含量降低。生草后土壤全磷含量随土壤深度的增加而增加,0~10 cm土层全磷量为清耕＞人工生草＞自然生草,0～10 cm土层的全钾含量依次为人工生草＞自然生草＞清耕。各处理土壤全钾含量变化差异不明显。应重视对果园草的追肥,采取及时施肥措施来补充果园草生长消耗的养分。