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Mô phỏng khí động học đóng vai trò quan trọng trong quá trình nghiên cứu, thiết kế ô tô, bên cạnh các thí nghiệm được thực hiện trong ống khí động. Trong đó, độ chính xác của kết quả mô phỏng và yêu cầu về tài nguyên tính toán phụ thuộc rất lớn vào quá trình chia lưới. Chất lượng lưới bị ảnh hưởng bởi nhiều yếu tố, trong đó có loại phần tử lưới được sử dụng. Trong nghiên cứu này, bốn loại lưới phi cấu trúc, bao gồm Poly-Hexcore, Hexcore, Polyhedral và Tetrahedral được sử dụng để đánh giá đặc tính khí động học của mô hình xe DrivAer Fastback thông qua phương pháp mô phỏng số. Các thông số của quá trình chia lưới khi sử dụng bốn loại lưới trên được phân tích và đánh giá. Kết quả mô phỏng số cũng được so sánh với kết quả thực nghiệm để đánh giá độ chính xác giữa các loại lưới được sử dụng. Kết quả cho thấy, loại lưới Poly-Hexcore là phù hợp nhất để sử dụng cho quá trình mô phỏng khí động học ô tô.

An ninh quốc gia (ANQG ) luôn là mối quan tâm hàng đầu của các nước, bởi lẽ đây là vấn đề tồn vong của các chủ thể chính trị cấu thành hệ thống quốc tế. Qua niệm về ANQG đối với các xã hội khác nhau và ở những giai đoạn lịch sử khác nhau, được thể hiện khác nhau. Từ chỗ vốn được hiểu một cách truyền thống là hoà bình, độc lập, chủ quyền quốc gia hoặc sự tồn tại của hệ thống chính trị. Hiện nay, dưới tác động của toàn cầu hoá, ANQG đã được hiểu một cách tổng thể hơn, bao quát hơn. Cùng với những thay đổi trong quan niệm về ANQG, tu duy chiến lược; bảo vệ chủ quyền, dưới tác động hai mặt của toàn cầu hoá cũng đang thay đổi về cơ bản. Bài viết này sẽ làm rõ một số nội dung liên quan đến sự thay đổi ấy và quan niệm của Đàng Cộng Sản Việt Nam về nhiệm vụ bảo vệ ANQG trong giai đoạn hiện nay.

Khảo sát thành phần dinh dưỡng, xử lý và sử dụng bùn đáy ao nuôi cá tra nhằm mục đích phân tích thành phần dinh dưỡng của bùn đáy ao nuôi cá tra thâm canh ở các tỉnh vùng Đồng bằng sông Cửu Long. Nghiên cứu được tiến hành với các nội dung chính: (1) phân tích thành phần dinh dưỡng bùn đáy ao nuôi cá tra; (2) sử dụng bùn đáy ao nuôi cá tra cho sản xuất nông nghiệp. Kết quả cho thấy có sự khác biệt ý nghĩa thống kê về hàm lượng dinh dưỡng ao nuôi cá tra giữa các qui mô nuôi, giữa các ao có chứng nhận và ao chưa chứng nhận, giữa ao nuôi bằng thức ăn tự chế biến và ao nuôi bằng thức ăn viên công nghiệp nhưng khác biệt không ý nghĩa thống kê giữa giai đoạn cá 500 g/con và giai đoạn cá khoảng 900 g/con. Thành phần dinh dưỡng bùn đáy ao nuôi cá tra có: 17,1% chất hữu cơ (CHC), 9,90% tổng carbon (TC), 2,04 mg/g tổng đạm (TN) và 0,96 mg/g tổng lân (TP); với giá trị pH là 6,7 và độ dẫn điện (EC) là 2,45 mS/cm. Khi sử dụng bùn đáy ao nuôi cá tra để trồng hoa màu thì có thể tiết kiệm một lượng phân đáng kể từ 9 - 100% lượng phân bón vô cơ tùy theo loại cây trồng, cải thiện năng suất và chất lượng sản phẩm. Sản xuất nông nghiệp bằng bùn đáy ao nuôi cá tra thâm canh là một trong những mô hình phát triển bền vững và góp phần làm giảm thiểu ô nhiễm môi trường khi bùn đáy ao nuôi cá tra thải trực tiếp ra môi trường không qua xử lý.

Bài báo trình bày kết quả nghiên cứu thiết kế, chế tạo và khảo nghiệm xe phun thuốc có người điều khiển trên đồng ruộng. Các kết quả khảo nghiệm cho thấy máy có thể phun được khoảng 500 lít/ha, năng suất làm việc thực tế có thể đạt 0,95 ha/giờ, độ tiêu hao nhiên liệu khoảng 0,5 lít dầu/ha. Đặc biệt máy có thể làm việc ổn định, chắc chắn và hiệu quả trên nền đất ruộng mềm, dễ lún ở đồng bằng sông Cửu Long. Máy có thể phun cho lúa ở các giai đoạn sinh trưởng khác nhau và đảm bảo an toàn cho sức khỏe của người vận hành.

Measuring implicit associations of self-concept with health or illness attributes may offer valuable insight into the mechanisms entailing the perception of one's own health, as explicit measures of self-reported health are usually influenced by social desirability or response bias. In this study, healthy participants performed a modified version of the implicit association test (IAT) investigating implicit associations between the self and either health or illness related representations. Behaviorally, implicit associations dominated for self-health pairing, and their strength was inversely correlated with depressive traits. Neurally, concomitant EEG recording showed significant modulations of the P1, LPP, and N4 components evoked by such pairings, suggesting a facilitation of sensory responses to self-related stimuli and differential emotional processes engaged to integrate health versus illness information into self-related representations. These data offer new clues to better understand the cognitive and affective mechanisms underlying unrealistic optimism and pathological awareness of health conditions in various clinical populations., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The proteomes of Listeria monocytogenes expressed in suspension and biofilm state, in the presence and absence of a carbon source, were analysed by two-dimensional electrophoresis with the help of computer software. The up-regulated proteins in each case were identified by peptide sequencing using electrospray ionisation tandem mass spectrometry and a database search against the Listeria genome was performed. Relevant functions could be attributed to a number of the induced proteins which contribute to the understanding of the mechanisms of starvation survival of L. monocytogenes in planktonic state and in biofilm.

The effect of preheating on the survival of L. monocytogenes in Richard's broth, which mimics the composition of Camembert cheese composition, was examined. Experiments were carried out to reproduce contamination of cheese with environmental heat-stressed cells of L. monocytogenes surviving hot-cleaning procedures. Cells in mid-log phase were heated for 30 min at 56 degrees C before being inoculated into Richard's broth. The pHs and temperatures of Richard's broth were chosen to recreate the conditions of curd dripping (pH 5, 25 degrees C), of the beginning of cheese ripening (pH 5, 12 degrees C), and of the beginning (pH 5, 4 degrees C) and the end (pH 7, 4 degrees C) of cheese storage. Immediately after heat treatment, the viability loss was especially high for strain 306715, which exhibited only 0.6% +/- 0.2% survival, compared with 22% +/- 8.7% for strain EGD. The percentages of the surviving heated cells that were injured were 93% +/- 8% for strain 306715 and 98% +/- 3% for strain EGD. The destruction of the surviving L. monocytogenes cells was accelerated when they encountered the pH and temperature conditions of Camembert cheese during manufacturing, ripening, and cold storage (pH 5 at 25, 12, and 4 degrees C, respectively). The multiplication of the surviving heated cells was retarded under favorable growth conditions similar to those of storage by the distributor and the consumer (pH 7 at 4 and 12 degrees C, respectively).

The responses of Listeria monocytogenes to acidic conditions were studied at the level of protein synthesis at a lethal acidic pH (acid stress) and an intermediary nonlethal acidic pH (acid adaptation). The radiolabeled acid-induced proteins were separated by two-dimensional (2-D) electrophoresis and analyzed by a computer-aided 2-D gel analysis system. The two acidic conditions upgraded a number of constitutive proteins and induced synthesis of a number of novel proteins. The majority of these induced proteins were common to the two pHs and the lethal acidic pH induced more proteins than the mildly acidic pH, suggesting that the responses to the two acidic conditions involve many common proteins and that additional proteins are required when the bacteria have to face more severe acidic conditions. In waiting for identification of more proteins involved in order to have a wholesome mechanistic picture of the acid response in L. monocytogenes, we present here the first results obtained from identification of the most abundant of these acid-induced proteins using peptide mass fingerprinting and matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) technique.

The physiological aspects of the response to acidic conditions and the correlated protein synthesis were studied by using Listeria monocytogenes grown in a chemically defined synthetic medium. This growth was greatly affected by pH of the medium. It decreased when pH declined and was arrested at pH 4. When pH went under 4, the bacteria began to die. If the bacteria had been adapted to an intermediary sublethal pH before imposition of lethal pH stress, they would have resisted better lethal pH. A prolonged treatment at intermediary pH, however, rendered the bacteria more sensitive to subsequent lethal pH. Organic volatile acids exerted a more deleterious effect on L. monocytogenes than inorganic acids at the same stressing pH. The acquired acid tolerance was conserved after several weeks of storage of the adapted bacteria at 4 degrees C. Acid stress and acid adaptation (tolerance) affected the synthesis patterns of bacterial proteins: Many proteins were repressed and several others increased in expression level. These acid-induced proteins were separated by two-dimensional (2D-) electrophoresis and analyzed by a computer-aided 2D-gel analysis system. The results obtained suggested that acid tolerance and acid stress responses require the synthesis of a certain number of shared proteins and that additional acid-induced proteins are needed when the bacteria must face more severe acidic pH.

Pigs are emerging as the most likely providers of genetically engineered organs and cells for the purpose of clinical xenotransplantation. Introduction of clinical trials has been delayed primarily by uncertainties regarding the risk of swine pathogen transmission that could harm the recipient. The concern that xenotransplantation carries the potential for a new epidemic has been highlighted by recent experiences with both bovine spongiform encephalopathy and human immunodeficiency diseases. As clinical trials have been postponed and xenotransplantation teams are working actively to gather data for an estimation of the risk, this review provides the reader with a state-of-the-art estimation of the microbiological hazards related to xenotransplantation of porcine organs to man. Particular emphasis is put on viral and retroviral hazards. Both current diagnostic tools and those under development are described, along with breeding strategies to provide donor animals that would not put the recipient or the general population at risk.

The proteins induced by the different stress conditions in Listeria monocytogenes were analyzed by two-dimensional (2-D) electrophoresis with the aid of a computerized 2-D gel analysis system. The stress conditions imposed were pH 4, pH 10, 0.015% sodium, dodecyl sulfate (SDS), 0.03% sodium deoxycholate and 4% ethanol. As previously seen for heat shock and cold shock, more than half of the proteins normally synthesized by Listeria cells were repressed under these stress conditions. Conversely, the synthesis of a great number of proteins was increased and novel proteins appeared upon stress. Each stress factor induced a specific set of proteins. These stress proteins were characterized by their apparent molecular mass and isoelectric point. No universal stress proteins were found to be common to all the stresses studied, while some proteins were commonly induced by two or three stress conditions. The degree of dissimilarity in stress responses was best illustrated by the induction of only two proteins common to exposure to the two detergents SDS and sodium deoxycholate. This work together with that on heat and cold shock, constitutes the basic step for the identification of stress proteins in Listeria.

Proteins secreted by sheep ovarian follicles at different stages of maturation (small healthy, large healthy or large atretic) and originating from ewes with different ovulation rates (homozygous carriers or noncarriers of the FecB gene) were analysed by two-dimensional electrophoresis (PAGE) followed by computerized image analysis. Follicles were incubated intact for 1 h to assess steroidogenesis, and then incubated for 24 h in the presence of [35S]methionine. Secreted proteins were then resolved by iso-electric focusing followed by migration on 10% acrylamide slab gels and fluorography. Incorporation of label into proteins was similar irrespective of genetic type or health status of the follicles (4-6%). Small follicles incorporated significantly less (P < 0.05) label. Over 100 spots were detected on the fluorographs. The presence of the FecB gene induced qualitative and quantitative changes in the follicular protein patterns. Frequency of detection of spots 116 and 129 was significantly higher (P < 0.01) in Fec+Fec+ compared with FecBFecB follicles (80% versus 8%). In addition, amounts of proteins present in spots 2 and 12 were increased in FecBFecB follicles, while those in spots 9 and 21 were decreased. Size and atresia affected protein patterns only quantitatively. Increased amounts of proteins in spots 1, 10, 38, 44 and 113 were associated with atresia (P < 0.05). Follicle enlargement was associated with increased (P < 0.05) amounts of proteins in spots 5 and 6 and decreased amounts of proteins in spot 16. Amounts of three proteins (33, 40 and 58) were related positively to oestradiol production in vitro before labelling.

The proteins induced by heat and cold shock in Listeria monocytogenes (pathogenic for humans) and L. innocua (nonpathogenic) strains were analyzed by two-dimensional (2-D) electrophoresis with the help of a computerized 2-D gel analysis system. Heat (49 degrees C) and cold (4 degrees C) shock repressed roughly half the number of proteins synthesized at normal temperature (25 degrees C) and decreased the level of numerous other proteins. Conversely, the synthesis of a great number of proteins was enhanced and novel proteins appeared upon temperature stress. There were more proteins induced in the L. monocytogenes strain than in the L. innocua strain. Each stress induced a set of specific proteins. There was overlap between these sets of proteins induced by heat and cold shock. Furthermore, a number of heat or cold shock proteins were found to be induced in both Listeria species and by both heat and cold shock in both species. The induction by heat shock was more intense than that by cold shock. The most strongly induced common stress protein of Listeria had a molecular mass of 17.6 kDa and an isoelectric point of 5.1.

A lymphoblastoid cell line (B1) was isolated in culture following a brief exposure to 5-azacytidine from peripheral-blood mononuclear cells of a boar previously injected with cells (Shimozuma) producing porcine retrovirus (Tsukuba-1) and suffering a severe non-neoplastic syndrome at autopsy. B1 cell line and 5 of its sublines were propagated for more than 100 generations, retaining doubling times comprised between 16.8 and 27.5 hr and growing readily in agarose or agar (plating efficiency: 5 to 50%). Karyotype analyses showed that 4 sublines were nearly diploid, except for cells of L14, which displayed a monosomy affecting chromosome 18 pair. Two sublines (L35 and L45) were considered as being of T-cell lineage, since MSA, antigen was observed on the surface of approximately 30% of cells. Three sublines (L23, L14 and L52) were considered of B-cell lineage, since membrane immunoglobulins were observed on the cell surface. In addition, sublines L23 and L52 were actively secreting immunoglobulin of mu isotype. Retrovirus particles were evidenced in gradient-purified preparation of 200-fold-concentrated cell culture supernatants of the B1 cell line, L14, L35 and L52 sublines, using both a reverse transcriptase activity assay and electron microscopic observation. These cell lines can be used to select for porcine retrovirus variants with transforming potential for lymphocytes of B and T lineages.

Porcine IgG, IgA and IgM were isolated from sow milk. They were systematically purified by a combination of gel filtration and ion exchange chromatography. The yields were 85%, 64% and 32%, respectively. These immunoglobulins were very pure, as checked by SDS-PAGE and Ouchterlony immunodiffusion. SDS-PAGE showed moreover the evidence of secretory component S in the IgA molecule and of joining piece J both in IgA and IgM molecules. The procedure can be used to purify immunoglobulin classes from other biological sources.

Lymphocyte subpopulations derived from different pig organs (blood, spleen, mesenteric lymph nodes) were separated by a simple, rapid and cheap panning technique, using either normal or ozone treated Petri dishes with bovine serum albumin. Slg+ lymphocytes could thus be obtained with a purity of up to 95% by adhesion onto Corning plastic dishes. The purified cells retained their proliferative activity with regard to lectins. The subpopulation including PT4 and PT8 was then separated by another panning on ozone-treated plastic dishes with a purity of 80-90%.