Spark discharge and high-speed impact treatment of turbostratic CNx powder

CN_x precursor powders (composition: 33.76 at.% C, 49.53 at.% N and 16.71 at.% H) having a turbostratic structure were obtained by pyrolyzing melamine. Following spark discharge treatment, the precursor becomes more ordered in structure. The order was increased with increasing treatment time. Photoluminescence (PL) analysis confirmed that the spark discharge had only a slight effect on the energy band of the turbostratic CN_x powder, namely a blue shift of 11 nm in the emission spectrum of the precursor. By contrast, the high-speed impact treatment clearly promoted the mass transfer between the CN_x particles.     

用焦磷酸络锰(Ⅲ)引发丙烯酰胺接枝魔芋粉合成增稠剂

用焦磷酸络锰的三价离子Mn^3 为引发剂，引发魔芋粉（KGM）与丙烯酰胺（AM）的接枝共聚。研究了引发剂浓度、单体浓度、pH值、反应温度、反应时间、反应介质以及KGM预处理方式等对接枝反应的影响，同时，还研究了产物的水溶性及增稠性。     

铁强化食盐的铁源筛选及稳定性研究

对铁强化食盐生产中不同铁剂对产品稳定性和品质的影响进行了研究。结果表明 ,以焦磷酸铁和乙二胺四乙酸铁钠为铁强化剂 ,稳定性较好 ,铁含量 (以铁元素计 )可达6 0 0mg/kg～ 12 0 0mg/kg ,颜色和口感不会明显改变。     

Growth and characterization of calcium pyrophosphate dihydrate grown in silica gel

Calcium pyrophosphate dihydrate crystals, which are responsible for various arthritic diseases, were grown in sodium metasilicate gel. Variations in gel density, pH value and concentration of the reactants were found to have profound effect on the growth of the crystals. The grown crystals were characterized using IR, XRD, TGA and optical microscopy.     

Suppression of Thermal Denaturation of Myosin Subfragment-1 of Alaska Pollack (Theragra chalcogramma) by Sorbitol and Accelerated Inactivation by Pyrophosphate

Thermal denaturation of myosin subfragment-1 (S-1), prepared from myofibrils (Mf) of Alaska pollack dorsal muscle by chymotryptic digestion, was well suppressed by sorbitol addition in a concentration dependent relationship. ATP and ADP also suppressed the ATPase inactivation significantly at different degrees. On the contrary, pyrophosphate (PPi) accelerated the inactivation by several-fold; half the maximal acceleration occurred at about 30 μn, M PPi concentration. The accelerated inactivation by PPi addition was remarkable at high-salt medium such as 0.5M KC1.     

Visual detection of melamine in raw milk using gold nanoparticles as colorimetric probe

We report the development of a simple and rapid colorimetric detection method for melamine in raw milk using gold nanoparticles as probe. This assay relies upon the distance-dependent optical properties of gold nanoparticles. In neutral media, melamine could rapidly induce the aggregation of gold nanoparticles, thereby resulting in red-to-blue (or purple) colour change. The concentration of melamine in raw milk can be determined by monitoring with the naked eye or a UV–vis spectrometer. The present limit of detection for melamine is 0.4 mg/L. The method is rather simple, and the whole process including sample pretreatment takes only 12 min at room temperature. The merits (such as simplicity, rapidity, low cost and visual colorimetry) make the proposed method specially useful for on-site screening melamine levels well below the current safety limit in raw milk.     

Study on effect of polydimethylsiloxane in intumescent flame retardant polypropylene

The effect of polydimethylsiloxane (PDMS) in intumescent flame retarded polypropylene (PP) containing melamine phosphate (MP) was studied using limiting oxygen index (LOI), UL-94 test, thermogravimetric analysis (TG), real time Fourier transform infrared (FTIR) and pyrolysis/gas chromatogram/mass spectrometry (Py–GC/MS). It was found that the addition of PDMS into the PP/MP composites leads to a decrease in the LOI values of the PP/MP/PDMS composites, and the values increase gradually with the increase of the PDMS content. The UL-94 test results indicate that the PP/MP/PDMS composite with 30% PDMS reaches the V-0 rating compared with no rating of the PP/MP composite at the same MP loading. The water resistance of the PP/MP/PDMS composites was investigated, and the improved water leaching of MP was observed. The TG and RTFTIR results illustrate the thermal stability of the PP/MP composites containing PDMS is improved. Moreover, the pyrolysis of the PP/MP/PDMS composites was studied by the Py–GC/MS method.     

电镀Sn-Ni合金在织物上的应用

采用已电镀铜的导电涤纶织物为基材,制备了枪黑色电磁屏蔽织物,并对其制备工艺及性能进行了初步的研究与探讨.利用正交试验方法研究了电流密度、时间、温度、pH、搅拌方式等工艺参数对Sn-Ni合金枪黑色镀层电阻及耐磨性能的影响,确定了较优的工艺条件:Jκ=0.8 A/dm2,t=15 min,θ=44℃,pH=8.6,阴极移动.实验表明,采用上述工艺制备的柔性电磁屏蔽材料具有良好的导电性能、耐磨性及附着力.     

焦磷酸盐镀铜工艺的改进

焦磷酸盐镀铜因具有镀液稳定、电流效率高、不含氰化物等优点而得到广泛应用.但是传统的镀液配方电流密度较小或含有机添加剂而导致镀液不稳定.通过在镀液中添加无机物来提高电流密度,讨论了无机添加物对电流密度的影响,给出了镀液配方及操作条件,提出了操作中应注意的问题.     

Effect of Tetrasodium Pyrophosphate on the Physicochemical Properties of Yogurt Gels

The effect of tetrasodium pyrophosphate (TSPP) on the properties of yogurt gels was investigated. Various concentrations (0.05 to 0.2%) of TSPP were added to preheated (85°C for 30 min) reconstituted skim milk, which was readjusted to pH 6.50. Milk was inoculated with 2% starter culture and incubated at 42°C until the pH reached 4.6. Acid-base buffering profiles of milk and total and soluble calcium levels were measured. Turbidity measurements were used to indicate changes in casein dispersion. Storage modulus (G′) and loss tangent (LT) values of yogurts were monitored during fermentation using dynamic oscillatory rheology. Large deformation properties of gels were also measured. Microstructural properties of yogurt were observed using fluorescence microscopy. The addition of TSPP resulted in the disappearance of the buffering peak during acid titration at pH ∼5.1 that is due to the solubilization of colloidal calcium phosphate (CCP), and a new peak was observed at lower pH values (pH 4.0-4.5). The buffering peak at pH 6.0 during base titration virtually disappeared with addition of TSPP and a new peak appeared at pH ∼4.8. The addition of TSPP reduced the soluble Ca content of milk and increased casein-bound Ca values. The addition of up to 0.125% TSPP resulted in a reduction in turbidity because of micelle dispersion but at 0.15%, turbidity increased and these samples exhibited a time-dependent increase in turbidity because of aggregation of casein particles. Gels made with 0.20% TSPP were very weak and had a very high gelation pH (6.35), probably due to complete dispersion of the micelle structure in this sample. The LT value of gels at pH 5.1 decreased with an increase in TSPP concentration, probably due to the loss of CCP with the addition of TSPP. The G′ values at pH 4.6 of gels made with ≤0.10% TSPP were not significantly different but the addition of ≥0.125% TSPP significantly decreased G′ values. The addition of 0.05 to 0.125% TSPP to milk resulted in a reduction in the yield stress values of yogurt compared with yogurt made without TSPP. Greater TSPP levels (>0.125%) markedly reduced the yield stress values of yogurt. Lowest whey separation levels were observed in yogurts made with 0.10% TSPP. High TSPP levels (>0.10%) greatly increased the apparent pore size of gels. Addition of very low levels of TSPP to milk for yogurt manufacture may be useful in reducing the whey separation defect, but at TSPP concentrations ≥0.125% very weak gels were formed.