Flexural vibrations of the prestressed toroidal shell

Numerical analysis of flexural vibrations of prestressed toroidal shel

Application of NASTRAN to propeller-induced ship vibration

An application of the NASTRAN program to the analysis of propeller-induced ship vibration is presented. The essentials of the model, the computational procedure, and experience are described. Desirable program enhancements are suggested

Asymmetric nonlinear dynamic response and buckling of shallow spherical shells

Numerical method and computer program for computing deflection response of thin shell

A pilot study on occurrence of Yersinia enterocolitica and Yersinia pseudotuberculosis in Latvian pigs at slaughtering

The aim of the study was to detect the distribution of presumptive pathogenic Yersinia spec1es in pigs of Latvian origm. In total tonsils of 108 pigs were collected from 6 farms m two abattoirs situated in different parts of Latvia. Samples were investigated by using direct plating on the selective CIN media and cold enrichment technique for 2 weeks. All presumptive isolates were confirmed biochemically. During the direct plating only 58% of cultures of Y.enterocolitica and 4 Y. pseudotuberculosts were recovered. Y. enterocolitica was isolated from the pig tonsil samples orig1nated from all six farms The distribution of positive samples among different farms varied from 15 to 45%. Y. pseudotuberculosis was recovered from 3 out of 6 herds studied rangmg from 5 to 25% on each positive farm. The mean prevalence of Y.enterocolitica and Y. pseudotuberculosis in all six farms was 31% and 8% respectively Results of study indicate that none of the investigated herds was free of potentially pathogenic Yersinia. The presence of Yersinia species in pigs indicates that a possibility for contamination with bacteria occurs during the offal removal of and meat mspection of carcasses. Further investigations on pathogenic properties and slaughtenng techniques at the slaughterhouses involved in this study should be continued

Whey permeate-derived milk acidifier for dairy calves

Received: April 15th, 2022 ; Accepted: May 12th, 2022 ; Published: May 27th, 2022 ; Correspondence: [email protected] milk acidifier obtained from whey permeate fermenting it with dairy propionic acid bacteria was tested in this study to evaluate the effects of milk acidification on the health and growth performance of pre-weaned dairy calves. The study consisted of 30 neonatal Holstein female calves, allocated to three treatments fed unacidified (Control group) or acidified (EG-1 and EG-2 groups) pasteurised milk during the 7–75 day age. Control and EG-1 were fed milk by divided method three times daily till one month of age, then twice daily until weaning; EG-2 was basically fed by the undivided method - one week three times daily (7–14 day age), then once daily. Results demonstrate that animal general health status and faecal scores (FS) were good and the tested acidifier can be used for pre-weaned calf milk acidification. Biochemical and haematological indices of blood at the 30 and 60 day age were within normal reference values with both - divided and undivided - milk feeding methods. Mean live weight (LW; 106.6 ± 9.40 kg on average) and live weight gain (LWG; 911.33 ± 109.04 g day-1 on average) at weaning did not differ between treatments (P > 0.05). Lower intake of starter feed associated with a larger amount of milk consumed was observed in EG-2 animals (P < 0.05). As the results observed regarding growth performance and health indices of all dietary treatment groups of calves were similar, we could anticipate that the acidification benefits would be greater when providing unpasteurised milk, or during the hottest weather when the risks of milk spoilage are greater

Total Syntheses of Amphidinolide H and G

Eureka! The first conquest of the exceptionally potent cytotoxic agent amphidinolide H, which exhibits activity in the picomolar range against human epidermoid cancer cells, was long overdue. The successful route critically hinges upon the scrupulous optimization of the fragment-coupling events (see picture; RCM=ring-closing metathesis) and on the careful adjustment of the peripheral protecting-group pattern

Total Syntheses of Amphidinolides B1, B4, G1, H1 and Structure Revision of Amphidinolide H2

Nature is a pretty unselective “chemist” when it comes to making the highly cytotoxic amphidinolide macrolides of the B/G/H series. To date, 16 different such compounds have been isolated, all of which could now be approached by a highly convergent and largely catalysis-based route (see figure). This notion is exemplified by the total synthesis of five prototype members of this family. Dinoflagellates of the genus Amphidinium produce a “library” of closely related secondary metabolites of mixed polyketide origin, which are extremely scarce but highly promising owing to the exceptional cytotoxicity against various cancer cell lines. Because of the dense array of sensitive functionalities on their largely conserved macrocyclic frame, however, these amphidinolides of the B, D, G and H types elapsed many previous attempts at their synthesis. Described herein is a robust, convergent and hence general blueprint which allowed not only to conquest five prototype members of these series, but also holds the promise of making “non-natural” analogues available by diverted total synthesis. This notion transpires for a synthesis-driven structure revision of amphidinolide H2. The successful route hinges upon a highly productive Stille–Migita cross-coupling reaction at the congested and chemically labile 1,3-diene site present in all such targets, which required the development of a modified chloride- and fluoride-free protocol. The macrocyclic ring could be formed with high efficiency and selectivity by ring-closing metathesis (RCM) engaging a vinyl epoxide unit as one of the reaction partners. Because of the sensitivity of the targets to oxidizing and reducing conditions as well as to pH changes, the proper adjustment of the protecting group pattern for the peripheral -OH functions also constitutes a critical aspect, which has to converge to silyl groups only once the diene is in place. Tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) turned out to be a sufficiently mild fluoride source to allow for the final deprotection without damaging the precious macrolides

Model based biotechnological potential analysis of Kluyveromyces marxianus central metabolism

The non-conventional yeast Kluyveromyces marxianus is an emerging industrial producer for many biotechnological processes. Here we show the application of a biomass-linked stoichiometric model of central metabolism that is experimentally validated, and mass and charge balanced for assessing the carbon conversion efficiency of wild type and modified K. marxianus. Pairs of substrates (lactose, glucose, inulin, xylose) and products (ethanol, acetate, lactate, glycerol, ethyl acetate, succinate, glutamate, phenylethanol and phenylalanine) are examined by various modeling and optimisation methods. Our model reveals the organism's potential for industrial application and metabolic engineering. Modeling results imply that the aeration regime can be used as a tool to optimise product yield and flux distribution in K. marxianus. Also rebalancing NADH and NADPH utilisation can be used to improve the efficiency of substrate conversion. Xylose is identified as a biotechnologically promising substrate for K. marxianus

Application of Permutation Genetic Algorithm for Sequential Model Building–Model Validation Design of Experiments

YesThe work presented in this paper is motivated by a complex multivariate engineering problem associated with engine mapping experiments, which require efficient Design of Experiment (DoE) strategies to minimise expensive testing. The paper describes the development and evaluation of a Permutation Genetic Algorithm (PermGA) to support an exploration-based sequential DoE strategy for complex real-life engineering problems. A known PermGA was implemented to generate uniform OLH DoEs, and substantially extended to support generation of Model Building–Model Validation (MB-MV) sequences, by generating optimal infill sets of test points as OLH DoEs, that preserve good space filling and projection properties for the merged MB + MV test plan. The algorithm was further extended to address issues with non-orthogonal design spaces, which is a common problem in engineering applications. The effectiveness of the PermGA algorithm for the MB-MV OLH DoE sequence was evaluated through a theoretical benchmark problem based on the Six-Hump-Camel-Back (SHCB) function, as well as the Gasoline Direct Injection (GDI) engine steady state engine mapping problem that motivated this research. The case studies show that the algorithm is effective at delivering quasi-orthogonal space-filling DoEs with good properties even after several MB-MV iterations, while the improvement in model adequacy and accuracy can be monitored by the engineering analyst. The practical importance of this work, demonstrated through the engine case study, also is that significant reduction in the effort and cost of testing can be achieved.The research work presented in this paper was funded by the UK Technology Strategy Board (TSB) through the Carbon Reduction through Engine Optimization (CREO) project