Determination of Volatile and Semivolatile Contaminants in Meat by Supercritical Fluid Extraction/Gas Chromatography/Mass Spectrometry

Meat products that were exposed to a warehouse fire were collected and examined to identify contaminants present in the samples. An extraction method using supercritical carbon dioxide at 100 atm and 60°C was developed to analyse and characterise volatile and semi-volatile compounds from the samples. The major volatile compounds were lipid oxidation products, such as hexanal and nonanal. Volatiles concentrations from fire-exposed meat products were compared to control samples to determine compositional differences. Aromatic and polycyclic aromatic hydrocarbons were identified, and naphthalene was measured in suspected fire-damaged meat products. Direct supercritical extraction from the meat samples proved to be a rapid and reproducible method to assess contamination in commercial meat products.     

节能电子产品设计将是2006年产业主题

Power Integrations期望2006年能够取得更出色的业绩.随着便携式电子产品的持续快速增长、铜等原材料成本的上扬以及更为严格的节能法规的相继出台,电源业的变化不断加速,这些市场变化都在推动和鼓励集成电路、非线性变压器及分立半导体在电源中的应用.作为电源高压IC的领先供应商,Power Integrations致力于协助电源客户来适应市场的变化.PI的使命是帮助设计师开发出比传统技术更小、更简单、更易于设计及更高效率的电源.     

技术发展为未来手机铺路

预计到2009年,大部分移动终端系统都将配备各式各样的无线存取技术,用以处理多媒体信息。要为这种发展趋势作好准备,业界就必须从现在开始积极创新无线频射(RF)设计。     

Magnesium Modified β-Tricalcium Phosphate Induces Cell Osteogenic Differentiation In Vitro and Bone Regeneration In Vivo

In vitro, in vivo, and clinical studies have shown how the physicochemical and biological properties of β-tricalcium phosphate (β-TCP) work in bone regeneration. This study aimed to improve the properties of β-TCP by achieving optimum surface and bulk β-TCP chemical/physical properties through the hydrothermal addition of magnesium (Mg) and to later establish the biocompatibility of β-TCP/Mg for bone grafting and tissue engineering treatments. Multiple in vitro and in vivo analyses were used to complete β-TCP/Mg physicochemical and biological characterization. The addition of MgO brought about a modest rise in the number of β-TCP surface particles, indicating improvements in alkaline phosphatase (ALP) activity on day 21 (p < 0.05) and in the WST-1assay on all days (p < 0.05), with a corresponding increase in the upregulation of ALP and bone sialoprotein. SEM analyses stated that the surfaces of the β-TCP particles were not altered after the addition of Mg. Micro-CT and histomorphometric analysis from rabbit calvaria critical defects resulted in β-TCP/Mg managing to reform more new bone than the control defects and β-TCP control at 2, 6, and 8 weeks (* p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001, and **** p ≤ 0.0001). The hydrothermal addition of MgO to the β-TCP surfaces ameliorated its biocompatibility without altering its surface roughness resulting from the elemental composition while enhancing cell viability and proliferation, inducing more bone regeneration by osteoconduction in vivo and osteoblastic differentiation in vitro.     

Unique orientation of lamellae in film processed poly (phenylene sulfide)

The morphology of poly(phenylene sulfide), PPS, obtained as processed film has been studied using wide angle X-ray scattering (WAXS), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). A unique morphology has been identified in the original film. The spherulites are very small in size and possess a cylindrical symmetry with their lamellae oriented on the edge. In these processed PPS films, the a-axis of the lattice is preferentially aligned perpendicular to the film plane, while the b and c axes are predominantly in the film plane. In the PPS isothermally crystallized from the melted, original film, there is no such preferential orientation. Thermal analysis of the original and melt crystal-lized PPS shows that while the degree of crystallinity is about the same, the nature of the amorphous phase in the two materials is different. In the original film, we did not observe a heat capacity increment at a glass transition temperature by DSC, indicating that all of the amorphous phase belongs to the category of rigid amorphous phase. In the melt crystallized PPS, a distinct glass transition was seen, though only a portion of the amorphous phase becomes mobile at T_g. The differences in orientation and mobility of the amorphous phase in the original film compared to melt crystallized PPS are explained by the different thermal processing procedures used for the two materials.     

Functional, Nutritional, and Rheological Properties of Protein Powders from Arrowtooth Flounder and their Application in Mayonnaise

ABSTRACT: Arrowtooth flounder soluble protein powder (AFSP) and arrowtooth flounder insoluble protein powder (AFISP) were evaluated for their functional, nutritional, and rheological properties. AFSP and AFISP contained 80% and 79% protein and 5.9% and 14.9% fat, respectively. Yield of AFSP (8.6%) was less than AFISP (13.1%). AFSP and AFISP had desirable essential amino acid and mineral contents. Emulsion stability of AFSP was greater than AFISP. Fat and water absorptions (mL/g protein) were 5.2 and 1.8 for AFSP, respectively, and 3.3 and 4.2 for AFISP Mayonnaises made from AFSP had greater emulsion stability than mayonnaise made from AFISP. Mayonnaises from both AFSP and AFISP possessed pseudoplastic and viscoelastic characteristics.     

EFFECT OF PRETREATMENT ON COLOR OF DEHYDRATED PRODUCTS

ABSTRACT

The effect of pretreatment on color of convective dried products (namely apple, banana, potato and carrot) was investigated. Five different types of pretreatment were taken into consideration; microwave, osmotic, sulfite, water blanching and steam blanching. Color characteristics were identified by measuring the color parameters (namely, Lightness (L), Redness (a) and Yellowness (b)) using a Hunter Lab chromatometer. The type of pretreatment was found to significantly affect the three color parameters. In addition, Redness (a) and Yellowness (b) were found to follow a first order kinetic model. Untreated dried materials showed an extensive browning, indicated by a significant drop of the L parameter and a corresponding increase of a, b parameters. Osmotically and microwave pretreated samples supressed browning compared to the untreated samples. In this case, lightness decreased slightly, while a, b increased slightly. Sulfite pretreatment prevented significantly color deterioration, while water and steam blanching also prevented enzymatic browning during convective drying.     

Influence of medium-chain triglycerides on lipid metabolism in the rat

Lipid metabolism was studied in rats fed diets containing corn oil, coconut oil, or medium-chain triglyceride (MCT), a glyceride mixture containing fatty acids of 8 and 10 carbons in length. The ingestion of MCT-supplemented, cholesterolfree diets depressed plasma and liver total lipids and cholesterol as compared with corn oil-supplemented diets. In rats fed cholesterol-containing diets, plasma cholesterol levels were not influenced by dietary MCT, but liver cholesterol levels were significantly lower than in animals fed corn oil. In vitro cholesterol synthesis from acetate-1-¹⁴C was lower in liver slices of rats that consumed MCT than in similar preparations from corn oil-fed rats. Studies of fatty acid carboxyl labeling from acetate-1-¹⁴C and the conversion of palmitate-1-¹⁴C to C₁₈ acids by liver slices showed that chain-lengthening activity is greater in the liver tissue of rats fed MCT than in the liver of animals fed corn oil. The hepatic fatty acid desaturation mechanisms, evaluated by measuring the conversion of stearate-2-¹⁴C to oleate, was also enhanced by feeding MCT. Adipose tissue of rats fed MCT converts acetate-1-¹⁴C to fatty acids at a much faster rate than does tissue from animals fed corn oil. Evidence is presented to show that the enhanced incorporation of acetate into fatty acids by the adipose tissue of rats fed MCT represents de novo synthesis of fatty acids and not chain-lengthening activity. Data are also presented on the fatty acid composition of plasma, liver, and adipose tissue lipids of rats fed the different fats under study.     

Comparison of interwell connectivity predictions using percolation, geometrical, and Monte Carlo models

Reservoir connectivity is often an important consideration for reservoir management. For example, connectivity controls waterflood sweep efficiency and it affects decisions concerning well placement and spacing. The uncertainty of sandbody distributions, however, can make interwell connectivity prediction extremely difficult. Percolation models are a useful tool to simulate sandbody connectivity behavior to estimate interwell connectivity.This study applies a percolation method to estimate interwell connectivity. Using results derived by Andrade, King, and others for fluid travel time between locations in a percolation model, we develop a method to estimate interwell connectivity. Four parameters are needed to use this approach: the net-to-gross ratio p_sand, the typical sandbody size, reservoir length and well spacing. To evaluate this new percolation method, the results are compared to results from geometrical models, Monte Carlo, and reservoir simulation.These methods were applied to estimate interwell connectivity for three non-communicating stratigraphic intervals in Monument Butte oil field, Utah. The results suggest that the percolation method can estimate the probability of interwell connectivity reliably for thin intervals for any values of p_sand, well spacing, and reservoir length. The geometrical model also performs well, but can only be applied in fields where the well spacing is less than one-half of the sandbody size.The proposed method requires that the reservoir interval for evaluation be sufficiently thin so that 2D percolation results can be applied. For thick intervals or heterogeneous sandbody distributions, the percolation method developed here is not suitable because it assumes thin layers. Future percolation research will be needed to adapt this new method to 3D cases.