阿维拉霉素高产突变株H15形态分化初步研究

采用电镜及荧光显微镜方法,对经60Coγ诱变筛选获得的绿色产色链霉菌(Streptomyces viridochromogenes)阿维拉霉素高产突变株H15的菌落、孢子丝、分生孢子分化特征进行了研究。与原始菌株4.1119不同的是,突变株H15形态呈现显著变异:灰白绿色菌落,直线型孢子丝,分生孢子表面光滑无刺突,而菌株4.1119为螺旋状孢子丝,孢子表面带刺。液体培养菌丝荧光染色结果表明,H15菌株在液体培养条件下菌丝团形态分化过程也发生显著改变,孢子萌发形成多隔室菌丝,放射状生长逐渐形成菌丝团,核心菌丝出现凋亡后,菌丝团直径增长停滞。与原始菌株相比,突变株H15菌丝的成簇、形成完整菌丝团需要较长时间(48h才形成完整菌丝团,245μm),菌丝团直径增长停滞阶段及凋亡的延滞使得产物阿维拉霉素得以较好积累,阿维拉霉素的合成主要集中在此阶段。此后菌丝生物量虽维持小幅波动,但对阿维拉霉素的积累没有意义。因此推测菌丝团的形成历程、停滞阶段菌丝团直径增长及凋亡"相对平衡"对于阿维拉霉素的积累可能有重要意义。     

Lead shot and teal (Anas crecca) in the Camargue, Southern France: Effects of embedded and ingested pellets on survival

The negative consequences of lead shot ingestion have been demonstrated in captive birds, and the prevalence of embedded shot has been measured in wild waterfowl several times. However, the long-term consequences of these two indirect outcomes of hunting on waterfowl survival have merely been investigated. Using data from about 40,000 X-rayed teals (Anas crecca), this study attempts to evaluate these effects. We used multivariate logistic regressions to model the probability of carrying shot in the flesh or in the gizzard while testing for various explanatory variables such as sex, age, time or morphological measures like mass and flattened wing length. Because of technical issues, we used a non-parametric sign test rather than a complete capture-recapture analysis to evaluate the effect of shot on teal survival. This test was applied to the differences in time between ringing and recovery for lead categories (no lead shot, ?1 shot in the flesh but none in the gizzard, ?1 shot in the gizzard but none in the flesh) compared two by two. We show that, overall, males are more likely to carry embedded shot than females whereas the latter are more likely to carry lead pellets in the gizzard. Similarly, adults are more likely to carry shot in the flesh whereas first year individuals are more likely to have pellets in the gizzard. Embedded shot tend to accumulate in the ducks body over time, i.e. with the number of encounters with hunters, with no significant effect on survival. Conversely, the probability of carrying shot in the gizzard decreases over time, because lead-poisoning quickly leads the individual to death. Several possible biological interpretations are put forward to explain those results. This study demonstrates that negative impacts of ingested lead on teal survival arise after only one single pellet is ingested, advocating the ban of lead ammunition.     

典型生物质颗粒燃料燃烧特性试验

为研究生物质颗粒燃料的燃烧特性及污染物排放特性,该文以国外引进的生物质颗粒燃料燃烧器为试验装置,选择了8种典型的生物质颗粒燃料进行试验研究。试验结果表明,挥发份含量越高,含水率越低,生物质颗粒燃料所需的点火时间越短,SO2、NOx等污染物排放质量浓度远低于国家标准,但存在着部分生物质颗粒燃料灰分含量过大、结渣严重等问题。对大多数颗粒燃料来说,软化温度越高,结渣率越低,当软化温度超过1 389℃时,不会发生结渣;Si元素、碱金属元素含量越高,越容易结渣,碱土金属元素含量越高,越抗结渣。玉米秸中Si的质量分数为27.70%,底灰结渣率达到48.84%,落叶松中Si的质量分数仅为9.76%,不结渣;使用添加剂后,玉米秸的底灰结渣率降低了22.77%。这将为设计适合中国国情的生物质颗粒燃料燃烧设备及改善燃料的燃烧性能提供依据。     

Monitoring the effects of pesticide pellets to address farmers' concerns on soil fauna,specifically earthworms

Slugs are a major pest in arable agriculture that are typically controlled by using pesticide-impregnated pellets (molluscicides). We received multiple requests from farmers in 2018 for research into the impact of slug pellets on earthworms because they had been told that ferric-based pellets were ‘worm-friendly’. We measured soil fauna feeding activities within Lumbricus terrestris middens on a replicated field plot experiment comparing the recommended product rates of a metaldehyde (4%) based or ferric phosphate EDDS (3%) based slug pellets. There was a significant decrease in feeding activity in the presence of either type of slug pellet, particularly in the top 25 mm of the soil indicating movement away from the pesticide. This could be explained by the significantly lower abundance (numbers and biomass) of earthworms in the topsoil. Four months after ferric phosphate-based slug pellet application, there was no significant difference between the control and treated plots in earthworm abundance, indicating the effects were temporary. In the laboratory, individual Lumbricus terrestris earthworms consumed up to 4 slug pellets over 14 days and no significant differences in biomass were measured. A burrowing fitness assay indicated that earthworms exposed to ferric phosphate-based slug pellets burrowed to a greater depth. This suggests an avoidance behaviour response, which could also explain the field results. A consultation with farmers (n = 68) rated this information service as useful and indicated widespread interest in minimizing the effects of pesticides on non-target soil fauna.     

生物质颗粒燃料储藏理化特性变化规律

为分析生物质颗粒燃料在北方气候下是否可以长期储藏,以及不同储藏方式对颗粒燃料理化特性的影响规律,2011年3月至8月期间,针对北京地区气候,对玉米秸秆和木质2种颗粒燃料,以袋装、半封闭、露天3种储藏方式开展储藏试验。试验结果表明,2种颗粒在3种储存方式下机械耐久性都保持在94.46%以上,生物质颗粒燃料未出现发霉现象,全水分和堆积密度变化规律受气候变化规律相吻合。其中玉米颗粒和木质颗粒的露天状态储存时全水分极差（2.42%和2.55%）和颗粒密度极差最大（0.12 t/m3和1.297 t/m3）。灰分和挥发份保持则稳定状态初始状态。这为生物质颗粒燃料的安全储存提供理论依据。     

柱塞式平模生物质成型机设计与试验

针对传统生物质平模成型机能耗高、磨损严重的问题,该文提出了一种柱塞式平模生物质致密成型方法,并设计了成型机样机。该样机通过斜盘与弹簧配合,驱动柱塞往复运动,柱塞在运动过程中仅对模具内的原料进行挤压。成型模具部分采用组合式设计,主要由平模与成型套筒组成,可在成型套筒外部加热,同时可更换长径比不同的成型套筒以适应不同生物质原料。该文以不同颗粒度玉米秸秆和刺槐为原料,在原料含水率为15%,斜盘转速为50 r/min,原料温度为室温的条件下进行了试验,结果表明柱塞式平模生物质成型方法可行,颗粒成型率均高于98%,成型密度大于1.1 g/cm3,机械耐久性高于97%。该文提出的成型方法为生物质致密成型技术提供参考。     

Impacts of pellet pH on nitrous oxide emission rates from cattle manure compost pellets

Previous reports indicated that the emission of nitrous oxide (N₂O) when manure compost pellets (MCP) were applied to soil was greater than when ordinary manure compost or inorganic fertilizer was applied, but that applying pellets of nitrogen-enriched manure compost, a by-product of deodorizing manure during composting, resulted in N₂O emission rates less than those from MCPs. To investigate the mechanism by which N₂O emission rates and cumulative emissions were reduced in nitrogen-enriched manure composts pellets (N+MCP), we studied the impact of pellet pH on N₂O emission, because pH is different between MCP (pH 8.6) and N+MCP (pH 5.3). In an incubation experiment, the pH of pellets was adjusted to five levels (5.3, 6.0, 7.0, 8.0 and 8.6) with acid or alkaline solutions, and the pellets were incubated without soil in a beaker at 30°C for 90 d (MCP) or 42 d (N+MCP). A large peak in N₂O emission rate was observed soon after beginning the incubation (within 1–3 d) in the neutral and alkaline treatments for both MCP and N+MCP, and these peaks corresponded to a rise in the pellet nitrite contents. Thus, this N₂O emission peak might have been generated by the denitrification of nitrite in the pellets. In the acid treatments of MCP, the N₂O emission was distributed more in the later incubation period (14–90 d), when the reduction of nitrate in MCP occurred. This led to a significant increase in cumulative N₂O emission as compared with the alkaline treatments for MCP. Regarding the mechanism by which N₂O emission was reduced in N+MCP, although larger cumulative N₂O emission rates in the earlier stage (0–14 d for MCP and 0–7 d for N+MCP) were observed when the pellet pH was adjusted close to 7.0, lowering the pH of MCP to 5.3 (the pH of N+MCP) did not demonstrate a significant decrease in cumulative N₂O emission as compared with the original pH treatment (pH 8.6). These results indicate that pellet pH might not relate directly to the mechanism by which N₂O emission was reduced in N+MCP.     

水葫芦颗粒燃料成型工艺优化

为了提高水葫芦颗粒燃料的成型品质,该文对水葫芦颗粒燃料的致密成型工艺进行了试验研究,分析了加工压力、温度、原料含水率和粉碎粒度与水葫芦颗粒燃料的颗粒密度和径向抗压力的关系。单因素和多因素正交试验研究结果表明:影响水葫芦颗粒燃料的颗粒密度的主次工艺参数排序为:压力粒度温度含水率;工艺参数温度、压力和粒度的对水葫芦颗粒燃料的径向抗压力的影响差别不大,而原料含水率的影响最小。水葫芦颗粒燃料的最佳工艺参数条件为:压力6 k N、温度100℃、含水率12%、粒度0.58 mm,在此最佳工艺参数条件下,水葫芦颗粒燃料的颗粒密度和径向抗压力可分别达到1 362.21 kg/m3和1.44 k N。研究结果为工业化生产高质量的水葫芦颗粒燃料提供理论依据。     

Effect of urea pellet size and dicyandiamide on residual ammonium in field microplots

Abstract

Nitrification of urea can be slowed by adding a nitrification inhibitor or by fertilizer localization. The purpose of this research was to compare the effects of urea pellet size (0.01, 0.1, and 1.0 g) and level of dicyandiamide (DCD) addition (0, 1, 2, 5, and 10% of N as DCD‐N) on residual ammonium in field microplots. Trials were conducted at ten locations in North Dakota during 1988 and 1989. Adding DCD to 0.01 g urea pellets slowed nitrification at all locations and the lower rates of DCD (1–2% of N as DCD‐N) often performed as well as higher rates. Increasing urea pellet size to 1.0 g was more effective in inhibiting nitrification than adding DCD to 0.01 g pellets. Increased pellet size plus addition of DCD led to a very slow nitrification. A 1.0 g urea pellet containing 1–2% of N as DCD‐N should be a practical fertilizer formulation where a very slow nitrification is required.     

Effects of manure-based urea pellets on growth,yield, and nitrate content in coriander,garden cress,and parsley plants

Various organic residues and animal manures represent an excellent matrix material for production of natural-based pellet fertilizers. Fully decomposed cow manure with 50% w/w urea was used for pellet production in densities of 400 or 800 kg/m³, representing low and high compact urea pellets. The growth of coriander (Coriandrum sativum L.), garden cress (Lepidium sativum L.), and parsley (Petroselinum crispum Mill.) were then evaluated under application of these pelleted urea compared to urea alone and unfertilized plants. The total amount of applied nitrogen (N) in the form of urea or pelleted urea was 300 mg/kg soil, wherein pelleted urea treatments, 30% of N was incorporated into the soil as urea alone before planting. The results showed that application of pelleted urea in low and high compactness resulted in different plant responses in the three vegetable crops. Plant growth and biomass production was increased in plants treated with urea or low compact urea pellets. Leaf N concentration and the Soil-Plant Analysis Development (SPAD) index were increased by low but not by high compact urea pellet application. Regardless of compactness, pellet treated plants had less nitrate content compared to urea treated plants. Number of flowering plants in coriander and garden cress was higher with high compact urea pellet and in unfertilized plants, whereas plants treated with urea or with low compact urea pellet showed fewer flowering plants. So, for production of these leafy vegetables low compact pellet is preferred.     

The incidence and significance of ingested lead pellet poisoning in British Wildfowl

The objective of this study was to assess the extent of lead pellet ingestion by British wildfowl, particularly ducks and geese, and to examine regional variations. The gizzard contents of 2445 shot and 238 found-dead birds were examined, and lead concentrations were determined for 1620 liver and 1841 wing bone samples. In addition, X-ray photographs and blood samples were taken from live-caught birds. Ingested lead pellets were found in 3·2% of the birds examined. For a range of species, including pink-footed goose, white-fronted goose, barnacle goose, wigeon, teal, pintail, shoveler, scaup and moorhen, recorded incidences were either very low or zero. Relatively high incidences were noted for swans, greylag goose (7·1% of shot birds), gadwall (11·8%), mallard (4·2%), pochard (10·9%), tufted duck (11·7%) and goldeneye (6·7%). Most ingested pellets originated from shotguns, though anglers' split shot were found in one pochard and four mute swans. A marked seasonal variation in the extent of pellet ingestion was noted for mallard, with a peak in September, and evidence of high levels immediately before and after the shooting season. Pellet ingestion by mallard was found to be of widespread occurrence, though with considerable variation in recorded incidence from place to place. Inland areas tended to be worse, with the highest incidences recorded for birds shot at flight ponds and other freshwater bodies. Six per cent of mallard shot at inland sites contained ingested pellets, compared with 2·6% of those collected from coastal areas. The observed extent of pellet ingestion in British mallard is calculated directly to cause the death of at least 8000 each winter. Some measures that could be taken to alleviate the lead-poisoning problem in Britain are discussed, and progress of the USA's non-toxic pellet programme is examined.     

Nitrogen release dynamics of a slow release urea pellet and its effect on growth,yield, and nutrient uptake of sweet basil (Ocimum basilicum L.)

Manure urea pellets were produced and their nitrogen release rate was evaluated in soil incubation at different water contents of 90, 75, and 60% soil filed capacity (FC). In another experiment, sweet basil growth was evaluated during eight months (with three shoot harvests) under the pellet application. The nitrogen release and pellet dispersion rates were slow after two months or at lower soil water content (60% FC), but they were significant after four months of soil incubation, or at higher soil water content (75 or particularly 90% FC). Application of pelleted urea reduced plant growth and yield at first harvest than urea treatment. However, at second and particularly at third harvest (and the average of three harvests) significant improvement in growth parameters of SPAD value, leaf area, plant height, shoot fresh weight, pot yield, and` leaf N and K concentrations were achieved by application of pelleted urea fertilization.     

基于CFD-DEM耦合法的灭火机风筒优化与试验

为了进一步研究风力灭火机的灭火性能,并防止灭完火的区域死灰复燃,在风筒进口增加了超细干粉灭火剂进行喷射灭火。喷射式风力灭火机的性能主要体现在出口风速、射程和喷射的稳定性上,而后两者分别主要由灭火剂颗粒的喷出的速度和风筒内滞留灭火剂的量决定的。该文采用6MF-30型风力灭火机使用的风筒为原型验证仿真模型的可靠性,采用CFD-DEM耦合的方法对喷射式风力灭火机的工作过程进行仿真模拟。以风筒收缩角、灭火剂添加位置、风筒长度作为因素,按照二次正交旋转组合设计进行仿真试验,进行显著性检验和方差分析,建立了回归方程。结果表明:3个因素相对颗粒喷出速度和风筒内颗粒数都具有显著相关性,显著水平分别为P0.0001和P0.001,而这3个参考因素与出口风速无明显相关性;3个参考因素中风筒长度是对机械性能影响最大的因素。采用响应面法、加权法综合对最佳参数组寻优,发现喷射式风力灭火机收缩角取20°,灭火剂添加孔道距进风口140 mm,风筒长度700 mm时喷射式灭火机性能得以提高。采用该参数组的虚拟试验结果显示,颗粒喷出速度提高至41.24 m/s,同时风筒内颗粒数降低至209个。实体样机验证试验表明:采用该参数组设计的风筒可以有效提高喷射式风力灭火机的喷粉射程2.15 m,缩短灭火时间1.7 s且无复燃。该研究为风力灭火机风筒优化模拟提供了参考。     

Microbiological survey of selected imported spices and associated fecal pellet specimens

A microbiological survey was performed on 4 selected imported spices: black peppercorns, white peppercorns, coriander, and fennel seed. Aerobic plate count values ranged from 10(4) to 10(7) colony-forming units (CFU)/g for black and white peppercorns and from 10(3) to 10(5) CFU/g for coriander and fennel seed. Combined results of the 3-tube most probable number procedure and the API 20E kit indicated the presence of Escherichia coli in 4 test samples of black peppercorns, 1 test sample of white peppercorns, and 1 test sample of coriander. Two test samples of black peppercorns were positive for Salmonella contamination. Among the various Enterobacteriaceae isolated from the spices, Enterobacter cloacae and Klebsiella pneumoniae were found most frequently in all spice types. Of 18 mammalian and avian fecal pellets removed from the spices and analyzed microbiologically, E. coli was found in only 2 pellet specimens. There was no apparent relationship between the enteric microflora found in spices and those found in the fecal pellets.     

Effect of Amylose Content on Expansion of Extruded Rice Pellet

Rice pellets were prepared by single‐screw extrusion cooking with an in‐barrel water content of 50 wt%. Three different types of rice, indica glutinous, japonica, and indica, were used as raw materials. Reconstituted rice flour was made to study the effect of amylose content on pellet expansion. The glass transition (T_g) and expansion (T_e) temperatures of extruded pellet were determined by differential scanning calorimetry (DSC) and noncontact infrared thermometer, respectively. The amylose content was not significantly affected by extrusion cooking. The reduction in intrinsic viscosity indicated that amylopectin experienced some degradation. The T_g and T_e were not functions of amylose content, which affected the expansion ratio of the pellets. The Gordon‐Taylor equation was applied to estimate the T_g of the rice pellets.     

Twin‐Screw Extrusion Processing of Rainbow Trout (Oncorhynchus mykiss) Feeds Using Various Levels of Corn‐Based Distillers Dried Grains with Solubles (DDGS)

Increasing demand for seafood products and rising demand for fish meal for commercial fish feeds is driving the search for effective alternative protein sources. Twin‐screw extrusion trials were conducted to study the production of nutritionally balanced feeds for rainbow trout fingerlings (Oncorhynchus mykiss). Six isocaloric (≈4.61 kcal/g) ingredient blends with a target protein content of >45% db were formulated with 0, 10, 20, 30, 40, and 50% distillers dried grains with solubles (DDGS) and other feed ingredients. The moisture contents of the diets were initially adjusted to 5–7% db, and then extruded at 250 rpm using dual 1.9 mm dies with varying amounts of steam (7.2–7.7 kg/hr) injected into the conditioner and water (4.3–6.5 kg/hr) into the extruder. Mass flow rates, moisture contents, and temperatures were measured during processing and moisture content, water activity, unit density, bulk density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water stability, and color were analyzed to quantify the effects of varying DDGS content on the extrudate physical properties. Significant differences (P < 0.05) among the blends were observed for color and bulk density for both the raw and extruded materials, respectively, and for the unit density and pellet durability index of the extruded products. There were also significant changes in redness and yellowness, but only minor changes in brightness, among the final products with increasing DDGS content. The compressive strength of the extrudates increased significantly with increasing DDGS. Expansion ratio of all pellets was low. All extruded diets achieved very good water stability.     

Spatial distribution of Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) in the soil of a poultry house along a breeding cycle

Alphitobius diaperinus (Panzer) is an insect pest of tropical origin introduced in temperate areas. Its spatial distribution in the soil of poultry houses was studied during a winter breeding cycle. Soil sampling was done after the chickens’ removal in three plots (walls, feeders and central area). Three physical parameters were measured: soil moisture, soil density and soil surface compactness. Furthermore, soil and litter temperatures were recorded during the chickens’ breeding period and the following cleaning period. Spatial structure of the insect population in the soil revealed a high heterogeneity: late instar larvae, nymphae and adults were located in the soil (down to 10 cm depth) under the feeders where soil density, surface compactness and moisture content were lower. Management practices greatly influence this spatial structure. Soil constitutes a favourable site for pupation and a refuge (overwintering site) for adults and larvae during stressful periods (decrease of soil temperature during the cleaning period). A. diaperinus reacts to more than one stimulus to locate suitable sites (structural edaphic parameters, hygrotaxis, thermotaxis). The survival of A. diaperinus in temperate area depends on the opportunistic use of suitable warm sites such as the soil layer in poultry houses.     

生物质成型颗粒燃料燃烧特性的试验研究

该文利用热重分析仪对玉米秸秆、木屑、混合木屑三种生物质成型颗粒燃料进行了理论分析，分段比较了三种颗粒燃料的燃烧特点及各段表观活化能和频率因子的热化学动力学参数，分析了成型处理工序对生物质燃烧特性的影响。结合颗粒燃料在燃烧炉中的实际燃烧特点，明确了影响颗粒燃料燃烧适应性的主导因素是挥发分的析出和燃烧速率，由此为改良低质颗粒燃料、提高燃烧炉适应性提出了指导性建议。     

Compaction of Corn Distillers Dried Grains

Corn distillers dried grains (DDGS) were compacted into cylindrical pellets (3.5 cm in length, 1.5 cm in diameter) utilizing a closed‐end die under axial stress from a vertical piston applied by an Instron universal testing machine. The effects of independent variables, including the raw material moisture content (25–35% db), processing temperature (100–120°C), pressure (12.5–37.5 MPa), and dwell time (5–15 sec) on pellet density, durability, and stability were determined using response surface methodology. Moisture content, temperature, and pressure significantly affected (P < 0.05) the properties of DDGS pellets, while the influence of dwell time was negligible (P > 0.05). Increasing temperature initially increased and then decreased unit density. High moisture and pressure had favorable effects on unit density and durability rating. The density ratio increased with increasing pressure and moisture content. The results suggested technical feasibility of compacting DDGS. For the range of variables tested, optimum levels were identified as 34.6% moisture content, 107°C press temperature, and 36.8 MPa pressure to obtain maximum durability and density and acceptable dimensional stability.     

Factors That Influence the Microwave Expansion of Glassy Amylopectin Extrudates

The microwave expansion of glassy, unexpanded amylopectin pellets was studied. Amylopectin was extruded at three levels of specific mechanical energy (483, 809, and 846 kJ/kg), and 35–40% moisture content, without expansion at the die. Glassy pellets were obtained by drying and equilibrating the extrudates at five water activities (a_w 0, 0.11, 0.33, 0.67, and 0.75). The pellets were characterized by measuring volume, porosity, and moisture content. The pellets were then expanded in a constant power microwave oven to determine the degree of expansion. When subjected to microwave heating, regardless of extrusion condition and initial a_w, the pellets expanded from the center where the highest temperature was recorded and then expansion advanced in the whole volume. Maximum expansion was reached after 30 sec of heating, after which samples started to burn from the center. Samples simultaneously expanded and lost moisture, both processes being faster and more intense for pellets of higher initial a_w. No expansion was observed for the pellets stored at a_w 0, while collapse was observed for pellets stored at a_w 0.73. A linear correlation between pellet expansion temperature and glass transition temperature was obtained. A hypothesis for the microwave expansion of glassy extrudates was formulated and represented on a state diagram.