Deposition of spray drift behind border structures

Windbreaks present a porous obstacle to the approaching airflow, forcing air to flow through the windbreak at a reduced speed and accelerate over the top. In this research, windbreaks were considered as border structures to mitigate spray drift. Air flows, with an interspace between it, particles are filtered from the flow by deposition on the windbreak. Hence there is a reduction in deposition in the downwind sheltered area (the ‘quiet zone’) behind the windbreak. Peak deposition in the sheltered area can occur at minimum wind speeds. The deposition profiles of spray drift behind various border structures were measured. In the first part, drift tests were performed in a wind tunnel. Artificial screens with various heights and open areas were tested. A row of plastic Christmas trees and natural canopies were also tested. Subsequently, drift experiments were performed under field conditions in a grassland with the artificial screens and a row of Fagus sylvatica trees. The artificial screens reduced spray drift deposition in the sheltered region, but significant deposition peaks were found behind the screens. The natural structures had potential to reduce drift deposition when their height was at least equal to the height of the spray nozzle(s). The drift deposition at short distances behind the natural structures was higher than deposition behind artificial structures, but conversely peaks in deposition in sheltered areas were not created by the natural structures.     

公路涎流冰的防治措施

本提出了涎流水的形成机理,并依据公路涎流冰形成规律提出了几种新的防治措施。对公路设计和施工有一定的指导作用。     

罩盖喷杆喷雾机的设计与防飘试验

在机动背负式喷杆喷雾机的基础上设计了一台适合大田作业的手扶式罩盖喷杆喷雾机,分别进行了田间和室内防飘性能试验。结果表明,罩盖喷雾能增加雾滴在冠层中的穿透性,尤其使用小流量喷头时防飘效果更加明显。罩盖能够显著增加药液在喷头附近的沉积,减弱雾滴向下风向的运动能力,减少飘失。使用ST110-015型喷头,喷雾压力0.4MPa时罩盖的防飘效果最好。在相同风速下,罩盖对雾滴的防飘失效果不同,对较小雾滴的防飘失效果优于较大雾滴。     

Selectivity of Herbicide and Rhizospheric Microbial Activity on Hymenaea corbaril L. Seedlings

Current knowledge about the behavior of forest species under herbicide treatment regarding selectivity, resistance, and fitotoxic effects is insufficient. This study assesses the selectivity of sulfentrazone and glyphosate on Hymenaea courbaril L. seedlings (jatoba) and the effects of this herbicide on the rhizospheric microbial activity of those plants. For this assessment, two experiments were conducted. In the first one, 10 treatments were compounded by the combination of two herbicides (glyphosate and sulfentrazone) applied in five doses (0.00, 0.09, 0.18, 0.35, and 0.70 L ha^?1). The second experiment assessed effects of the combination of five doses of the herbicide sulfentrazone and two types of substrate (rhizospheric and nonrhizospheric cultivated with jatoba seedling). To assess the selectivity of seedling to the herbicide, visual assessments of toxicity were carried out 15, 30, 45, and 60 days after the application. To determine the effect of sulfentrazone on rhizospheric activity, the basal respiration and of microbial biomass carbon (CBM) associated with substrates was evaluated. A good tolerance of the seedling with the herbicide was observed even at higher doses, indicating potential use in control of weeds in areas of jatoba planting in the initial phase of development. Regarding microbiological indicators, it is verified that the evolution of carbon dioxide carbon (C-CO₂) and CBM were effective in the presence of herbicides, which can constitute auxiliary tools for environmental-impact monitoring of the herbicides.     

开口双圆弧罩盖减少雾滴飘失效果的CFD模拟

利用Fluent软件模拟分析开口双圆弧罩盖喷雾的雾滴飘失,并与常规无罩盖喷雾进行比较。在模拟的6种风速(1．4m／s、2m／s、3m／s、4m／s、5m／s和6m／s)下,开口罩盖减少雾滴飘失的效果分别为：15．56％、22．90％、24．39％、21．71％、25．66％和24．14％。     

“Π”型循环喷雾机防飘性能试验

为适应篱架型作物病虫害防治要求,研制了能够将未沉积在靶标上的农药雾滴截留回收再利用的循环喷雾机,并与传统果园风送喷雾机进行了防飘性能对比试验。结果表明:在作业行下风向,"Π"型循环喷雾机空中飘失的药液比传统果园风送喷雾机减少了97.9%;在飘失距离内的地面飘失量比常规果园风送喷雾机减少了99.3%。     

Internal fracture fixation

Over the past decade, many improvements to small animal internal fracture fixation have been developed, including improved fixation techniques and a more diverse selection of implants. The understanding that appropriate fixation selection is based on a plethora of biologic, mechanical, and clinical factors has also emerged. Classically, the methods of internal fracture fixation have used pins, wires, screws, and plates to rigidly stabilize fractures that have been anatomically reduced with significant disruption to the biologic fracture environment. Newer methods attempt to minimize trauma to the soft tissues surrounding a fracture and promote biologic osteosynthesis using such implants as interlocking nails and plate-rod fixations. This review provides an overview of both the traditional and current principles of small animal internal fracture fixation.     

Interpreting the spatio-temporal patterns of sea turtle strandings: Going with the flow

Knowledge of the spatial and temporal distribution of specific mortality sources is crucial for management of species that are vulnerable to human interactions. Beachcast carcasses represent an unknown fraction of at-sea mortalities. While a variety of physical (e.g., water temperature) and biological (e.g., decomposition) factors as well as the distribution of animals and their mortality sources likely affect the probability of carcass stranding, physical oceanography plays a major role in where and when carcasses strand. Here, we evaluate the influence of nearshore physical oceanographic and wind regimes on sea turtle strandings to decipher seasonal trends and make qualitative predictions about stranding patterns along oceanfront beaches. We use results from oceanic drift-bottle experiments to check our predictions and provide an upper limit on stranding proportions. We compare predicted current regimes from a 3D physical oceanographic model to spatial and temporal locations of both sea turtle carcass strandings and drift bottle landfalls. Drift bottle return rates suggest an upper limit for the proportion of sea turtle carcasses that strand (about 20%). In the South Atlantic Bight, seasonal development of along-shelf flow coincides with increased numbers of strandings of both turtles and drift bottles in late spring and early summer. The model also predicts net offshore flow of surface waters during winter - the season with the fewest relative strandings. The drift bottle data provide a reasonable upper bound on how likely carcasses are to reach land from points offshore and bound the general timeframe for stranding post-mortem (< two weeks). Our findings suggest that marine turtle strandings follow a seasonal regime predictable from physical oceanography and mimicked by drift bottle experiments. Managers can use these findings to reevaluate incidental strandings limits and fishery takes for both nearshore and offshore mortality sources.     

喷雾机雾滴运行时间和沉降规律的试验

利用光电原理,采用湿度传感器和毫秒计设计了测量雾滴运行时间的试验方案,并测量了4种常见喷嘴在不同机器前进速度和喷雾压力下的雾滴运行时间。结果表明,在喷雾机正常工作状态下,由于雾锥角的存在,雾滴总是超前于喷杆到达目标物上,这个时间上的提前量可以为变量喷雾系统的响应时间作必要的时间补偿。并通过采用三因素三水平的正交试验和方差分析,说明了喷嘴类型对雾滴运行时间的影响极为显著,而机器前进速度对雾滴运行时间的影响在5%的水平上显著。利用荧光跟踪试验,研究了3种喷嘴的不同时刻的沉降规律,从雾滴沉降的角度揭示了空心锥喷嘴存在很大的漂移性。     

Droplet size spectra and drift effect of two phenmedipham formulations and four adjuvants mixtures

The effect of 4 adjuvants on two formulations of phenmedipham (EC and SC) applied with three types of hydraulic nozzles (hollow cone, flat fan and air induction) was evaluated using a wind tunnel to determine spray drift potential (DP). The volume median diameter (VMD) and the percentage by volume of droplets less than 100 μm diameter was determined using a Malvern particle size analyser. In a wind tunnel DP was measured between 2 and 6 m downwind of the nozzle on glass fibre collectors using a fluorescent tracer. The EC formulation produced a smaller VMD and larger DP than the SC formulation irrespective of any effect due to adjuvants. DP increased as the proportion of small droplets increased.