A novel four-quadrant power supply for low-energy correction magnets

This paper describes an efficient power supply to feed low-energy correction magnets in particle accelerator applications, where a controlled current with trapezoidal profile and four-quadrant operation is needed. The selected design is based on an AC–DC matrix converter topology, which uses the Space Vector Modulation (SVM) technique to obtain a near unity power factor at the AC input and output DC current regulation. This topology allows performing high-frequency isolation, while four-quadrant operation is maintained, and reducing volume and weight as compared with the classical thyristor (SCR)-based technology. Control tasks are implemented on an all-digital control card: output current regulation is accomplished in a digital signal processor device and SVM is implemented in a Field-Programmable Gate-Array. Simulations and experimental results of a 1.2 kW prototype validate the design.     

Optimal deflection and stacking sequence prediction of curved composite structure using hybrid (FEM and soft computing) technique

Engineering with Computers - The bending deflections and the corresponding optimal fiber angle sequences of the subsequent layers have been predicted in this article using a hybrid technique. The...     

25-kW/50-kHz generator for induction heating

The authors present the features, technology, and construction of a transistorized generator for induction heating operating over the 4-50 kHz frequency range. This type of 25 kW output-power generator allows replacement of the electronic tube generators for most of their applications. The advantages of this new generator are more energy efficiency, extended life, reduced size, separated heating station of the generator, and connection by flexible cable. In addition, the generator has incorporated a frequency automatic tracking system that allows operating without any adjustments over a wide frequency range     

On prediction and experimental assessment of engine-bearing performance

Semi-analytical methods of predicting journal loci and dynamic oil film pressures in engine bearings are discussed and methods are described, utilizing simplifying features in the solution of the Reynolds equation. These are similar to, but more accurate than, the analytic short- or long-bearing solutions and it is shown that the results predicted by computer programs based on these new methods agree well with the results given by more ‘exact’ methods. Comparisons of journal-centre orbits and of oil film pressures with results taken from test rigs and from an operating engine are given.     

纳米化肉桂醛抗辣椒疫霉病原菌增效作用

肉桂醛是一种天然的食源性抗菌剂,在食品加工、香料、制药、日用化学品等方面都有广泛应用。但由于它难溶于水、容易氧化等性质,增加了其在实际应用中的难度,从而导致其药效降低。作者对其进行纳米化,形成了一种透明、低黏度的动力学和热力学稳定体系,并将纳米化前后的肉桂醛对辣椒疫霉的抑菌活性进行对比。结果显示:纳米化后的肉桂醛具有较好的水溶性和稳定分散性;纳米化肉桂醛的粒径分布均匀,平均粒径为38.9 nm,均分布在15~60 nm之间;纳米化后的肉桂醛具有更好的抑菌效果,抑菌能力提高了50%~100%。总而言之,纳米化修饰提高了肉桂醛在食品和农业领域中的应用潜力。     

High Flexibility of RNaseH2 Catalytic Activity with Respect to Non-Canonical DNA Structures

Ribonucleotides misincorporated in the human genome are the most abundant DNA lesions. The 2′-hydroxyl group makes them prone to spontaneous hydrolysis, potentially resulting in strand breaks. Moreover, their presence may decrease the rate of DNA replication causing replicative fork stalling and collapse. Ribonucleotide removal is initiated by Ribonuclease H2 (RNase H2), the key player in Ribonucleotide Excision Repair (RER). Its absence leads to embryonic lethality in mice, while mutations decreasing its activity cause Aicardi–Goutières syndrome. DNA geometry can be altered by DNA lesions or by peculiar sequences forming secondary structures, like G-quadruplex (G4) and trinucleotide repeats (TNR) hairpins, which significantly differ from canonical B-form. Ribonucleotides pairing to lesioned nucleotides, or incorporated within non-B DNA structures could avoid RNase H2 recognition, potentially contributing to genome instability. In this work, we investigate the ability of RNase H2 to process misincorporated ribonucleotides in a panel of DNA substrates showing different geometrical features. RNase H2 proved to be a flexible enzyme, recognizing as a substrate the majority of the constructs we generated. However, some geometrical features and non-canonical DNA structures severely impaired its activity, suggesting a relevant role of misincorporated ribonucleotides in the physiological instability of specific DNA sequences.