Physicochemical properties of the thermal gel of water-washed meat in the presence of the more soluble fraction of porcine sarcoplasmic protein

We investigated the physicochemical properties of the thermal gel of water‐washed pork meat (WWM) in the presence of the soluble fraction of porcine sarcoplasmic protein (SP) obtained with ammonium sulfate at 75 percent saturation. Two precipitated fractions of SP were obtained at 0–50 percent and 50–75 percent saturation, named SP‐f1 and SP‐f2, respectively, and the soluble fraction obtained at 75 percent saturation, SP‐f3, was used. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that SP‐f3 contained mainly glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), while SP‐f1 and SP‐f2 had other SPs such as phosphorylase b, enolase, actin and phosphoglycerate mutase. The gel strength of WWM was greater when SP‐f3 rather than one of various animal proteins such as bovine plasma (BP), egg white, or whey protein isolates (WPI), was added and SP‐f3 had a gel‐enhancing effect as good as that of polyphosphate (PP). The gel strength of WWM with added SP‐f3 increased significantly with NaCl at 0.15 mol/L or more, but not in the absence of NaCl (0 mol/L). The effect of SP‐f3 was evident at neutral pH and maximum gel strength was obtained at a pH above 6.0. Differential scanning calorimetric (DSC) analysis showed that an endothermic peak corresponding to myosin heads in WWM shifted to a lower temperature with the addition of SP‐f3, as in the case of PP, though there was no such shift in the presence of other animal proteins (BP, egg white and WPI), suggesting that SP‐f3 increases the gel strength of WWM through the dissociation of actomyosin similar to PP. Scanning electron microscopy (SEM) revealed wall‐like structures among the protein strands in the WWM gel matrix in the presence of SP‐f3. The results of DSC and SEM indicated that the formation of a gel network in meat products is reinforced with GAPDH in SP after the interaction between GAPDH and myofibrillar protein.     

浅谈孔隙率对沥青路面的影响

沥青混合料的孔隙率是一个重要的设计参数，其对于沥青路面的强度和使用性能有着重要的影响。在施工时，由于施工条件和设备的影响，不可能达到设计的孔隙率，于是一般要求用压实度作为施工时的一个控制指标，将沥青路面施工后的孔隙率控制在一个可接受的范围。在路面使用的初期，必然会有一段时间处于未完全压实工作状态，这种工作状态下，沥青路面能够提供的是未完全稳定的早期强度。在设计时，需要对比多个级配的混合料，确定合理的早期强度。     

Simultaneous measurement of soil water and soil hardness using a modified time domain reflectometry probe and a conventional cone penetrometer

Soil strength and water content are important indices for assessing soil resistance to root growth and soil compaction both of which affect other soil properties. Therefore, simultaneous measurement of soil penetration resistance (PR) and soil water content can aid agricultural land management. We measured PR with a conventional cone penetrometer, followed immediately by determining water content using a modified TDR probe inserted into the penetrometer hole. From the results of a field feasibility test, soil water content was measured satisfactorily and correlated well with data obtained by the gravimetric method, except for those data from near the surface owing to soil disturbance when the cone penetrometer was extracted after the PR measurements. Field results demonstrate that PR and soil water content have three‐dimensional variability, with a markedly different distribution pattern between cultivated and subsoil layers at the field scale. Overall, the variability in the PR and soil water data is similar to that reported in previous studies. We conclude that our method produces results helpful to field management of soil and water because it is based on a simple and easy technique for the simultaneous measurement of soil water content and PR.     

测试胶合板胶合强度的研究

通过对有关胶合强度测试的几个试验结果的分析,表明我国胶合板国家标准对胶合强度试验方法的规定具有先进性、合理性和可行性。     

后期热固化处理对竹基纤维复合材料性能的影响

对竹基纤维复合材料进行两种条件(80℃处理8h和50℃处理24 h)的热固化处理后,观测其表观形貌,并进行拉伸、压缩、水平剪切性能以及疲劳性能检测.结果表明:经过热固化处理后,竹基纤维复合材料表面有不连续的微小裂纹产生,其拉伸、压缩、水平剪切性能略有提高,疲劳性能则无显著变化.     

Effect of Tillage System on Soil Strength and Bulk Density of Vertisols

Improving the soil environment for seedling emergence and plant growth is possible using a good tillage system. From March 1993 until June 1994, the effect of tillage system and plant residue incorporation practices on the bulk density and the soil strength of the surface layer of a vertisol (very fine, smectitic, thermic, chromic Haploxerert), on a less than 1 % slope, was investigated. The two tillage methods were moldboard (T1) and chisel (T2). The two plant residue incorporation dates were in August (R1) and in October (R2). Results indicated that R1 gave significantly higher bulk density than R2, while the different tillage treatments had no significant effect. Soil strength was significantly lower under T1 and R2 than under the other treatments.     

ZnO/Na 2 O(mol)对cBN陶瓷砂轮性能的影响

通过DSC -TG综合热分析、X衍射分析、线膨胀测试仪、扫描电镜等测试方法研究了ZnO/Na 2 O(mol)（ Z 值）对Li 2 O -K 2 O -SiO 2 -Al 2 O 3 -B 2 O 3 系陶瓷结合剂及立方氮化硼砂轮性能的影响，结果发现：ZnO能够抑制α -石英晶相析出，诱导析出低膨胀晶体Li 2 OAl 2 O 3 7.5SiO 2 ，并随着 Z 值的增加，α -石英减少，Li 2 OAl 2 O 3 7.5SiO 2 晶体逐渐增多， Li 2 OAl 2 O 3 7.5SiO 2 晶型结构趋于完整，晶粒尺寸减小，结构更加致密；当砂轮配方一定时，砂轮的体积密度、抗弯曲强度、洛氏硬度均随着 Z 值的增加而增大，气孔率减小，磨削（干磨）铸铁（QT400）时磨耗比先增加后减小；当 Z =0.75时，结合剂的膨胀系数为6.902 9×10 -6 K - 1 ，耐火度为805 ℃，砂轮的烧结温度为845 ℃，抗弯曲强度为73.97 MPa，气孔率为15.65%，磨耗比最大为156.42%.     

Failure criterion for timber beams loaded in bending,compression and shear

Abstract

Based on the elastic–plastic strength calculation, necessary for precise data explanation, a derivation is given of the failure criterion for combined bending, compression and shear. This exact limit state criterion should replace the unacceptable unsafe criteria of Eurocode 5 (EN 1995-1-1:2004). It is shown that the principle used thus far, of limited “flow” in axial compression as a determining failure criterion, for example, predicting no influence of a size effect, does not hold. Instead, it is derived and confirmed by the data that bending tension failure is always determining, showing the existence of a size effect, and correction of the existing calculation method is therefore necessary. Because of the primary importance of the size effect for the strengths, also for combined bending–compression, a simple derivation of the size effect design equations is given and discussed in an appendix.     

长输管道的试压

长输管道试压是管道施工中的一道重要工序,是对管材和焊接质量的综合检验。从管段划分、试压介质的选择、试验压力的确定等方面对试压工作进行了论述,介绍了国内外先进的施工实例和试压理念,旨在推动实现试压工作的专业化,保证管道长期运行的安全性。