Effect of machining parameters in ultrasonic vibration cutting

The ultrasonic vibration cutting (UVC) method is an efficient cutting technique for difficult-to-machine materials. It is found that the UVC mechanism is influenced by three important parameters: tool vibration frequency, tool vibration amplitude and workpiece cutting speed that determine the cutting force. However, the relation between the cutting force and these three parameters in the UVC is not clearly established. This paper presents firstly the mechanism how these parameters effect the UVC. With theoretical studies, it is established that the tool–workpiece contact ratio (TWCR) plays a key role in the UVC process where the increase in both the tool vibration parameters and the decrease in the cutting speed reduce the TWCR, which in turn reduces both cutting force and tool wear, improves surface quality and prolongs tool life. This paper also experimentally investigates the effect of cutting parameters on cutting performances in the cutting of Inconel 718 by applying both the UVC and the conventional turning (CT) methods. It is observed that the UVC method promises better surface finish and improves tool life in hard cutting at low cutting speed as compared to the CT method. The experiments also show that the TWCR, when investigating the effect of cutting speed, has a significant effect on both the cutting force and the tool wear in the UVC method, which substantiates the theoretical findings.     

制汤工艺条件对猪排骨蛋白质溶出率的影响

以排骨蛋白质溶出率为指标,通过单因素试验及正交实验优化排骨汤煮制的工艺条件。结果表明:传统瓦罐煲汤法的骨水比例1:6(g:mL),煮沸后恒温120min,蛋白质的溶出率为19.73%。压力锅炖汤法的压力0.10MPa,骨水比例1:3(g:mL),煮制180min,蛋白质的溶出率达52.82%。木瓜蛋白酶用量2.4%,骨水比例1:4(g:mL),50℃,pH7.0,酶解420min,蛋白质的溶出率达到71.86%。3种制汤方法中酶解制汤法最佳,其水解液无苦味,色泽金黄,具有浓郁的排骨汤香味。     

兔肉发酵香肠菌种配比及发酵条件的研究

用植物乳杆菌(Lp),嗜酸乳杆菌(La)和戊糖片球菌(Pp)3个菌种进行耐盐和耐亚硝酸盐试验,观察其在不同温度条件下的生长情况,然后通过正交试验确定3者配比。试验结果表明,3个菌种均可以作为兔肉发酵香肠的发酵剂,优化的配比是1.0%,0.6%,0.3%,发酵温度为30℃,RH 90%,发酵22～24 h,接种量为10~7cfu/g。     

Process Optimization and Characterization of Popped Brown Rice

The popping process was optimized for brown rice based on an expansion ratio. A central composite design with interactive effect of three independent variables, including salt content (1–2.5 g/100 g raw material), moisture content (13–17 g/100 g raw material), and popping temperature (210–240°C) was used to study their effects on the expansion ratio of rice using response surface methodology. The experimental values of expansion ratio were ranged from 5.24 to 6.85. On fitting the experimental values of expansion ratio to a second order polynomial equation, a mathematical model with the predictability was developed with the statistical adequacy and validity (p ? 0.05). From the model, the optimal condition including salt content (1.75 g/100 g raw material), moisture content (15 g/100 g raw material), and popping temperature (225°C) were predicted for a maximum expansion ratio of 6.79, which was then proved to be 6.85 through experiment. Raw and popped brown rice were investigated for physical properties including hardness, L*, a*, and b* value, length/breadth ratio, bulk density, and minerals, which showed the significant differences. The optimized popped rice sample was evaluated for structural, spectroscopic, and thermal properties, which showed the significant difference from raw rice.     

造纸法低定量烟草薄片打浆工艺及配抄特性研究

研究了低定量造纸法烟草薄片中的打浆工艺及配抄特性。研究表明:烟混浆打浆度为60°SR,外混浆打浆度为62°SR,烟混浆和外混浆浆料配比为6:1,且烟混浆中烟末浆和烟梗浆比例为1:1时,烟草薄片片基的各项性能指标达到最优。     

在靠近流浆箱处淀粉和填料同时混合工艺

采用闪急混合工艺使得在最接近流浆箱处向浆料中加入助留剂和施胶化学品等造纸添加剂,并使之迅速和有效地混合。这项多功能混合技术可以做到在同一地点同时将填料、助留剂一起加入到流浆箱中。该工艺操作简单,具有非常短的响应时间,填料留着率更高,纸张性能更优越。由于减少了添加剂在过程中的循环,响应时间非常快速,减少了传统混合过程的水或滤液的量,从而降低了能源消耗,降低了添加剂用量并使工艺过程净化。     

松茸菌汤熬制工艺参数优化及风味成分分析

以云南产新鲜松茸菌为主要原料,研究松茸菌汤熬制的主要工艺参数。以菌汤中固形物溶出率和蛋白质溶出率为考察指标,通过单因素试验和正交试验分析和讨论,确定松茸菌汤熬制工艺参数,并对松茸菌汤中的氨基酸、呈味核苷酸和风味成分进行分析。结果表明：松茸菌汤熬制的最佳工艺为料液比1∶60（g/mL）、熬制时间90 min、熬制火力中火（1 000 W）,此时菌汤中固形物溶出率为49.68%,蛋白质溶出率为45.74%;菌汤中总氨基酸和游离氨基酸均为17 种,含量分别为109.60 mg/100 mL和41.20 mg/100 mL;呈味核苷酸5’-肌苷酸二钠和5’-鸟苷酸二钠含量分别为2.0 μg/mL和28.4 μg/mL;气相色谱-质谱联用测得菌汤中挥发性物质共28 种,其中醇类物质所占比例最大。     

酶解法提取鳕鱼肝油的生产工艺研究

以鳕鱼肝脏为原料,采用木瓜蛋白酶水解提取鳕鱼肝油,选用提取率作为评价指标,通过单因素实验和响应面实验确定最佳的酶解提取工艺,并从鱼肝油的提取率、品质方面将其与传统淡碱水解法进行比较。实验结果表明,最佳酶解工艺条件为料液比1∶1.5、酶解p H 6.5、加酶量3 270U/g、酶解温度50℃、酶解时间2 h。在最佳酶解工艺条件下,鳕鱼肝油提取率可达到93.44%,且品质良好,酸价5.49 mg/g,碘价148.31 g/100 g,过氧化值7.49 meq/kg。酶解法鳕鱼肝油提取率及品质均优于传统淡碱水解法。     

施氮量与基追比例对烟叶品质及氮肥利用率的影响

通过3年的田间试验,研究了不同施氮量和基追比例对烟叶化学成分、感官质量及氮肥利用率等的影响。结果表明,降低施氮量增加了烟叶的总糖、还原糖含量和糖碱比,降低了总植物碱、总氮、钾含量及钾氯比,改善了烟叶感官质量;降低施氮量显著降低了氮素积累量、来自肥料和土壤的氮量,显著提高了氮肥利用率。相同施氮量,随追肥比例增加,2009和2012年度烟叶的总糖、还原糖含量及糖碱比先增加后降低,总植物碱、总氮含量先降低后增加;2010年烟叶总糖、还原糖含量及糖碱比降低,总植物碱和总氮含量提高。2009、2010年度感官质量分别以追肥比例为70%和50%的处理最佳;2012年度高施氮量以追肥比例为70%处理最佳,低施氮量以50%处理最好。增加追肥比例显著提高了氮肥利用率。通过3年研究发现,施氮量从90 kg/hm²降至45~60 kg/hm²,追肥比例增至50%~70%可改善烟叶感官质量及提高氮肥利用率。     

Nutrition, metabolism, and fertility in dairy cows: 1. Dietary energy source and ovarian function

In previous studies, high plasma insulin was associated with earlier resumption of postpartum estrous cycles in dairy cows. The objective of this experiment was to quantify hormonal and ovarian responses to dietary starch and fat contents. Thirty cows were fed on a standard diet from calving until 40 d in milk (DIM) and then 6 cows were allocated to each of 5 isoenergetic diets containing 231, 183, 159, 135, and 87 g of starch and 39, 42, 43, 45, and 48 g of fat/kg of dry matter (DM) for diets 1 to 5, respectively, until 70 DIM. Estrus was synchronized at 60 DIM. Between 60 and 70 DIM, energy intake, milk yield, and energy balance were similar among diet groups. Plasma insulin-to-glucagon ratio increased with increasing dietary starch and decreasing dietary fat concentrations, reaching a break point at 159 g of starch, 43 g of fat/kg of DM (diets 1 to 5: mean 3.86, 3.78, 3.59, 2.98, 2.06 ± standard error 0.22). Growth hormone, insulin-like growth factor-I, and leptin did not vary among diets. The greatest dietary starch concentration was associated with elevated plasma urea-N (diets 1 to 5: mean 3.69, 3.01, 2.94, 2.95, 2.75, ± standard error 0.13 mmol/L, respectively) and delayed postovulatory progesterone increase (progesterone at 3 to 5 d postovulation for diets 1 to 5: mean 2.7, 5.9, 4.2, 5.6, 4.3 ± standard error 0.9 ng/mL, respectively). The number of small (<5 mm) ovarian follicles was positively related to starch intake (r = 0.381) and plasma insulin concentration (r = 0.402). It is concluded that to maintain adequate insulin-to-glucagon ratio in cows at the start of the breeding period, dietary starch concentration should be above 160 g/kg of DM and dietary fat below 44 g/kg of DM, and this should have a positive effect on ovarian function.