氧化鸡肉脂肪制备肉味香精前体物质的研究

研究以鸡肉脂肪为主要原料制备肉味香精的前体物质,通过单因素和正交试验确定氧化反应的最佳反应条件.结果表明氧化鸡肉脂肪的最佳条件是:氧化温度为120℃,氧化时间为3h,VE的添加量为1.0%,不添加水和NaCl.在最优条件下进行氧化试验,得到产物的酸值和过氧化值分别为1.472 mg/g和193.51 mmol/kg,感官评价值为4.905,具有典型特征的鸡肉香气.     

低压电力线载波通信信道特性仿真研究

针对低压配电网电力线载波通信信道存在频率选择性衰减,建立了电力线信道模型,并对频率为50 Hz~20 MHz的信道频率响应进行了分析。由于电力线信道存在多径效应,考虑到信道路径对信号衰减的影响,建立了多径信道衰减模型,并对多径信道下的信号频率特性进行仿真,得出的试验结果与预期一致。对电力线载波通信信道进行了改进,在OFDM子载波信道中插入导频符号,改进后系统的仿真误码率较改进前降低了10%。     

软上地基上加筋碎石垫层工作性状试验研究

通过模型试验研究了加筋和不加筋碎石垫层在软土地基上的承载特性,分析了垫层厚度、加筋材料、加筋层数、筋体布置位置等因素对垫层承载特性的影响。结果表明：垫层厚度对地基沉降影响明显,合理的垫层厚度能有效地降低地基的沉降;加筋后的碎石垫层对降低地基沉降的效果更明显,同等条件下,土工格室的加筋效果优于土工格栅;加筋层数及筋体布置位置对加垫碎石垫层承载特性有一定影响,层数越多加筋效果越好,将筋体布置在垫层下部时效果最好;加垫层能在一定程度上提高地基基床系数,其中土工格室加筋碎石垫层对提高地基基床系数效果最好。     

胡椒碱对人胃癌SGC-7901细胞抗肿瘤活性的体外实验研究

胡椒碱（Piperine）是一种从胡椒属植物中提取的生物碱,具有镇静、抗炎、抗肿瘤等多种药理活性.探讨胡椒碱对人胃癌SGC-7901细胞的增殖抑制和诱导凋亡的作用.采用MTT比色法测定其对SGC-7901细胞增殖抑制率;通过免疫荧光法、流式细胞术、Western blot法对其进行抗癌机制研究.MTT结果显示Piperine处理细胞72h的IC50值为37.41 μmol·L-1,且呈现时间剂量依赖性; Hoechst33258染色荧光显微镜观察发现Piperine能诱导SGC-7901细胞核形态学改变,部分细胞呈现典型的凋亡形态学特征;Annexin V-FITC/PI荧光双染结果亦证实Piperine可以诱导SGC-7901细胞发生凋亡;DAPI和DCFH-DA染色流式细胞术分析显示Piperine诱导SGC-7901细胞G2/M期阻滞、细胞活性氧产生增加; Western blot分析发现Bcl-2蛋白表达减少,Bax蛋白表达逐渐增加,呈现剂量依赖性,且Bax/Bcl-2比例增加.因此,Piperine具有抑制SGC-7901细胞增殖和诱导凋亡的抗肿瘤活性.     

四角切圆煤粉锅炉燃烧温度场的数值模拟

四角切向燃烧煤粉锅炉的炉内过程是一个非常复杂的湍流流动与燃烧化学反应过程.利用流体力学软件"F luent"对此锅炉燃烧情况进行数值模拟,得出炉内的温度场.通过对锅炉燃烧温度场的模拟预测温度场的趋势,结果完全符合炉膛燃烧的规律.锅炉燃烧温度场的模拟对于锅炉的安装和改造有指导意义.     

铝蜂窝负载锰基催化剂的制备及其在室温下去除低含量甲醛的性能

采用水热共沉淀法和原位氧化还原法制备MnO_x/MgAl类水滑石(Mg₃Al₁-LDHs)催化剂,以水玻璃作为黏结剂将其负载到铝蜂窝上,用于室温下去除甲醛。通过X射线衍射(XRD)、热重分析(TG)、X射线光电子能谱(XPS)、N₂吸附-脱附、傅里叶变换红外光谱(FT-IR)等手段进行表征。表征结果表明：MnO_x/Mg₃Al₁-LDHs具有典型类水滑石结构,大量结合水和羟基; MnO_x为δ-MnO₂和Mn₃O₄的混合物,具有高比例Mn⁴⁺/Mn³⁺和丰富的吸附氧。实验结果表明：室温(25 ℃,相对湿度60%)下反应4 h后,MnO_x/Mg₃Al₁-LDHs催化剂可将甲醛质量浓度由1.30 mg/m³降至0.10 mg/m³以下,且经过8次和连续15 d实际测试,表明催化剂具有良好的稳定性和甲醛去除效果。MnO_x/Mg₃Al₁-LDHs催化剂最佳负载量(质量分数)为5%,风扇最佳功率为10 W,空气中湿度对甲醛去除效果影响较小,该催化剂具有较强水分抵抗能力,反应温度提升会较大程度提高甲醛去除效果。     

海上油田多元热流体吞吐气窜调剖实验研究及应用北大核心CSCD

目的多元热流体吞吐技术是海上稠油开发的一种经济、有效的技术,但随着吞吐轮次的增加,暴露出易发生“气窜”的问题,即N_(2)、CO_(2)等非凝析气体容易突破到周边生产井,导致其电泵气锁关井影响生产。方法以渤海NB稠油油田为研究对象,采用可视化实验方法,研究防止气窜的治理策略。结果筛选出适合油田的磺酸基泡沫调堵体系,命名为QGQ-4,优化研究出最佳注入参数为质量分数0.4%、泡沫干度在60%以上、地面预制泡沫注入方式。与单纯多元热流体驱相比,泡沫辅助多元热流体驱可提高油藏波及,有效封堵气窜通道,提高平面波及系数37%。结论研究成果现场应用后,受益井初期高峰日产油增加到措施前的1.5倍,日产油由措施前的50.5 m^(3)增至措施后的高峰日产油75.7 m^(3),取得了较好的增产效果。     

Annealing effects on the structure and hardness of helium-irradiated Cr2AlC thin films

Cr₂AlC MAX phase thin films prepared by radio-frequency magnetron sputtering were irradiated at room temperature by 100 keV helium ions to a fluence of 1 × 10¹⁷ ions cm⁻². The effects of thermal annealing on the structural and mechanical properties of the helium-irradiated Cr₂AlC films as well as the helium release were investigated by grazing-incidence X-ray diffraction (GIXRD), Raman spectroscopy, and scanning electron microscope (SEM) in combination with nano-indentation and elastic recoil detection (ERD) analysis. The irradiation-induced structural damage in the Cr₂AlC is significantly recovered by thermal annealing at temperatures around 600℃, attributed to high defect diffusivity. After annealing to 750℃, the hardness of irradiated films recovered almost completely, which is ascribes to both defect recombination and reformation of damaged chemical bonds. Substantial helium release occurring at this annealing temperature is closely related to the damage recovery due to helium irradiation.     

Thermal stability and performance of optimized ZrCx diffusion barriers in ceramic coating systems for ATF applications

Surface-modified Zr alloy claddings with advanced ceramic coatings are promising materials for accident-tolerant fuel (ATF) systems to meet stringent safety regulations concerning light water reactors. The applications of ceramic coatings are, however, limited as a result of inferior thermal stability when used in conjunction with Zircaloy-4 (Zry-4) substrates. Herein, the thermal stability of sub-stoichiometric zirconium carbide barrier layers as a function of composition was studied. Integrated ceramic coatings comprising ZrC_0.55 diffusion barriers and a Cr₂AlC top layer were synthesized via a magnetron sputtering method. After rapid thermal annealing, the ZrC_0.55 barrier layer having a thickness of 0.5 μm effectively prevented the inter-diffusion between Cr₂AlC and the Zry-4 substrate, thereby ensuring retention of the structural integrity of the integrated ceramic coating system for ATF applications.     

Degradability and biocompatibility of bioglass/poly(amino acid) composites with different surface bioactivity as bone repair materials

Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants.