Cattle manure and inorganic nitrogen fertilizer application effects on soil hydraulic properties and maize yield of two soils of Murewa district,Zimbabwe

This study set out to determine the effects of cattle manure and inorganic N‐fertilizer application on the hydraulic properties and maize yield of a clay and sandy soil in a smallholder farming area of Zimbabwe. Four fields classified as homefields (HF: more fertile and closer to homesteads) and outfields (OF: less fertile and further from the homesteads) were selected on clay and sandy soil. They were subjected to four treatments, control (no fertility amendment), 5, 15 and 25 t/ha cattle manure + 100 kg/ha N (as ammonium nitrate) for 7 years. A two‐way randomized complete block design was used with fertility and field type as the two factors. Clay soil hydraulic properties, which included density of macropores with a diameter >300 μm, unsaturated hydraulic conductivity, steady‐state infiltration rate, moisture retention under low suction and maize grain yield, were significantly improved (P < 0.05) by fertility management compared with the control and were generally comparable between the HF and OF. Fertility management significantly improved maize grain yield on sandy soils but did not enhance hydraulic parameters, thereby indicating poor responsiveness in structural build‐up. On the other hand, significantly different hydraulic parameters between the sandy soil HF and OF suggested effects of other factors not related to soil fertility and field type treatments. We therefore concluded that application of a high rate (25 t/ha) of cattle manure and inorganic N‐fertilizer is beneficial for fertility restoration to the degraded OFs with associated comparable hydraulic properties on HFs and OFs on clay soil, unlike on sandy soil.     

Characterization and Film-Forming Properties of Gelatins from Whitemouth Croaker (Micropogonias furnieri) Skin and Bones

The Whitemouth croaker (Micropogonias furnieri), due to its abundance, is considered one of the most traditional and important species fished in the coastal waters and estuaries of South America. The aim of this work was to produce biopolymeric films of gelatins obtained from skin and bones of Whitemouth croaker. The fish gelatins were characterized through the yield, chemical composition, physiochemical, and rheological properties. The films were characterized by tensile strength (TS), elongation at break (EAB), water vapor permeability (WVP), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and optical properties. The values of protein yield, hydroxyproline content, gel strength, melting temperature, gelling temperature, and viscosity of the skin gelatin were higher than the values of the bone gelatin. The films obtained of skin gelatin showed all properties and thermal analysis superior in relation to the films of bone gelatin; this can be justified by the best physicochemical and rheological characteristics of the skin gelatin.     

Investigation of the high-amylose maize starch gelatinization behaviours in glycerol-water systems

The effect of glycerol on gelatinization behaviours of high-amylose maize starch was evaluated by confocal laser scanning microscopy (CLSM), scanning electronic microscope (SEM), differential scanning calorimetry (DSC), texture analyzer (TPA) and rheometer. Gelatinization of the high-amylose maize starches with glycerol content of 10% (w/w) began at 95.4 °C (T_o), peaked at 110.3 °C (T_p), and completed at 118.9 °C (T_c). The birefringence began to disappear at around 100 °C and finished at 120 °C which corresponded well to the onset and conclusion temperatures obtained by DSC. The high-amylose maize starch granules maintained original morphological structure at 100 °C and swelled to a great degree at 110 °C. The high-amylose maize starch paste formed at 100 °C showed the lowest hardness (39.92 g), while at 120 and 130 °C, showed the highest hardness (610.89 g and 635.43 g, respectively). It should be noted that in going from 100 °C to 110 °C there is a significant increase in the viscosity of the slurry solution. The identical apparent viscosity was observed when the shear rate exceed 100 s⁻¹, resulting from the high-amylose maize starch granules were completely gelatinized at 120 °C, which was consistent with DSC analysis.     

Wheat flour enriched with oat β-glucan: A study of hydration,rheological and fermentation properties of dough

The objective of this study was to evaluate the effects of the incorporation of oat β-glucan (OβG) on the hydration, rheological and fermentation properties of wheat flour dough. Wheat flour was substituted with OβG at levels varying from 1 g/100 g–5 g/100 g. The addition of OβG significantly increased water absorption and dough development time. The dilution effect of OβG, competing for water and interaction between OβG and gluten proteins, deteriorated the gluten network structure and reduced the stability of dough. Rheological evaluation revealed an increasing tendency to solid-like behavior with increasing addition of OβG. Regarding dough fermentation properties, OβG had no effect on yeast activity but reduced the gas retention capacity of dough. Our findings indicate that OβG is a key component that determines the properties of dough, and excess OβG exhibited poorer processing characteristics compared with control.     

Comparison of Conventional Washing Processing and pH Shift Processing on Gelation Characteristics of Bighead Carp (Aristichthys nobilis) Muscle Proteins

In this study, gelation characteristics of bighead carp (Aristichthys nobilis) protein isolates prepared by pH shift processing were investigated as compared with those of surimi prepared by conventional wash processing. Results showed that the gel from alkali-aided protein isolate exhibited a higher breaking force than that from conventional washed surimi (p < 0.05). However, the gel from conventional washed surimi had higher whiteness (p < 0.05) and lower expressible moisture (p < 0.05). The rheological study showed that protein isolates exhibited different storage modulus and loss tangent patterns from conventional washed surimi during heating. Acid-aided processing could lead to higher denaturation and dissociation for fish muscle myosin and a coarser gel network from the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) pattern and the scanning electron microscopy (SEM). Overall, there is a potential to apply pH shift processing, especially alkali-aided processing, to extract more proteins from bighead carp muscle for the production of surimi-based food.     

猪粪施用量对红壤旱地理化性质及酶活性的影响

为研究猪粪的合理施用及其对红壤旱地地力提升的效应,利用在第四纪红壤旱地中连续3年分别施用0、7.5、15、30、45 t·hm~(-2)猪粪的小区定位试验,比较不同处理下菠菜和玉米地上部生物量、土壤相关理化性质、碳氮磷循环相关酶活性的差异。结果表明:菠菜和玉米地上部生物量、土壤有机质、土壤全量和速效态氮磷钾含量均随猪粪施用量的增加呈线性增加。当猪粪施用量达45 t·hm~(-2)时菠菜、玉米平均地上部生物量分别达到11.48、20.84 t·hm~(-2),土壤有机质和全氮、全磷含量分别达14.6、1.07、0.73 g·kg~(-1),土壤碱解氮、有效磷、速效钾含量分别达85.47、106.9、411.7 mg·kg~(-1),但与猪粪施用量为15和30t·hm~(-2)时土壤养分含量的差异不显著,而土壤中与碳氮磷循环相关的6种酶活性则与猪粪施用量呈线性相关,且在施用量为30或45t·hm~(-2)时出现显著差异;6种酶活性与土壤有机质、养分含量间均具有显著或极显著正相关关系。研究结果显示,第四纪红壤旱地在本试验猪粪施用量范围内,土壤有机质和养分含量、酶活性等指标均随施用量的增加而相应提高,作物地上部生物量亦呈线性增加,但同时须注意土壤速效态养分含量过高可能带来的氮磷流失加剧等问题。     

谷子秸秆剪切力与其饲料营养特性变化规律及相互关系

为探究谷子秸秆力学性质与其饲料特性的变化规律及相互关系，选用谷物完熟期的谷子秸秆，将其分为5段（近根部、中下部、中部、中上部、上部）并每隔7 d进行秸秆节间、茎节力学性质（剪切、压缩）和饲料特性（形态指标、营养成分）测定。试验结果表明：谷物完熟后，随着时间的推进，秸秆节间、茎节剪切力、抗压强度、干物质含量、纤维素含量、半纤维素含量和木质素含量总体上呈增大趋势，而秸秆含水率、当量直径、横截面积、线性密度和粗蛋白含量总体上呈减小趋势。谷子秸秆单位直径剪切力与含水率和线性密度呈负相关关系（R2≥0.903），与其干物质、纤维素、半纤维素和木质素含量呈正相关关系（R2≥0.845），与其粗蛋白含量无显著相关关系（P>0.05）。采收期内，谷子秸秆基部起秸秆剪切力至顶部逐渐增大，且剪切力与当量直径、横截面积呈正相关关系（R2≥0.916）。试验表明谷子秸秆饲料特性指标验证试验值与预测值相对误差不大于6.48%，预测模型合理。测量秸秆剪切力可用于预测其形态指标参数和营养成分含量，进而一定程度地反映秸秆饲用价值和反刍动物择食趋向。采收期内，谷子中部及以上秸秆单位直径剪切力显著小于其近根部（P<0.05），更适合饲用；且谷物完熟后，及时采收可避免秸秆饲用价值降低。该研究可为高效利用谷子秸秆资源提供参考。     

真空复合轧制自磨锐割刀与其结合界面组织性能研究

采用真空复合轧制工艺，将3种钢板（GCr15、Q420、IF）轧制成梯度复合材料，对其结合界面处的微观组织、成分及硬度分布、抗剪强度进行了检测，并对梯度材料自磨锐割刀进行了田间试验。结果表明，不同板层界面处材料间相互咬合形成较为紊乱的冶金结合方式，界面处元素相互扩散形成过渡区，组织缺陷较少。结合界面处的抗剪强度均超过了国标要求，且断裂方式为韧性断裂，不同界面间存在较为平缓的硬度梯度变化。梯度材料自磨锐割刀后刀面、刀尖及刃口材料为GCr15钢，硬度高、耐磨性好，前刀面的硬度呈梯度变化，磨损均匀，作业过程中可始终保持刀尖前凸，刃口曲率半径变化较小，能够长时间保持刃口的锋锐性与再生作物的低损伤切割。田间试验结果表明，相同作业条件下，梯度材料自磨锐割刀耐磨性是市售割刀的3倍以上。     

Urban land-use impacts on composition and spatiotemporal variations in abundance and biomass of earthworm community

Soil fauna can sensitively respond to alterations in soil environment induced by land-use changes.However,little is known about the impact of urban land-use changes on earthworm communities.In this study,three land-use types(i.e.,forest,nursery and abandoned lands)were chosen to identify differences in diversity,abundance and biomass of earthworm community in Kunming City.Urban land-use had a pronounced difference in species composition,evenness and diversity of earthworm communities.Forest land had the highest density,biomass and diversity of the earthworm communities.Total abundance was dominated by endogeic species in nursery land(70%)and abandoned land(80%),whereas in the forest land,the earthworm community comprised epigeic,endogeic and anecic species.Temporal changes in earthworm density and biomass were also significantly affected by land-use change.Total density and biomass of earthworms in the forest and nursery lands were highest in September,but highest in the abandoned land in October.The influence of soil physicochemical properties on the earthworm density and biomass also varied with land-use types.Soil temperature significantly affected earthworm density and biomass in the three land-use types.Soil pH was positively correlated with earthworm biomass in the forest land,but negatively associated with earthworm density in the abandoned land.Soil organic matter was positively correlated only with density and biomass of earthworms in the nursery and abandoned lands.Our results suggest that the species composition,abundance and biomass of earthworm communities can be determined by the modification of soil properties associated with urban land-use type.     

沙柳多元醇液化产物流变性能的研究

沙柳木粉在液化剂和催化剂的作用下制成的液化产物可生产制作聚氨酯、环氧树脂、胶黏剂等。研究沙柳液化产物的流变性能,可探索宏观流变性质与液体微观内部反应机理之间的关系,优化设备结构和加工工艺条件,对其高效利用有着重大意义。本试验将沙柳木粉在浓硫酸催化条件下进行多元醇液化,通过改变液化处理条件(反应时间、反应温度和催化剂用量)制备具有不同流变性能的沙柳液化产物。利用旋转型流变仪对所制备的沙柳液化产物进行流变性能测试和分析。沙柳木粉液化条件的单因素试验和正交试验分析结果表明:影响沙柳液化产物黏度的主要因素是反应时间,其次是反应温度和催化剂用量,最佳工艺条件为反应时间70 min、反应温度170℃、催化剂用量5%。在最佳工艺条件下,剪切速率为78.87 s-1时,黏度为0.26 Pa·s。红外光谱(FT-IR)分析得出,液化物中纤维素被大量降解,半纤维素和木质素部分降解,羟基增加,生成更多的反应活性官能团,此条件下液化反应更加充分,流体黏度较大。流变性能测试结果显示:稳态扫描测试时,黏度随剪切速率的增加逐渐减小,表现出剪切变稀的现象;剪切应力随着剪切速率的增加逐渐升高,表现出假塑性流体的性质。通过动态频率扫描曲线变化规律分析,储能模量和损耗模量随着角频率的升高而逐渐增加,复数黏度却随之减小。