Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China

During a survey of freshwater diatoms from Mojiang River, Chebaling Nature Preserve in Shaoguan City, Shixing County, Guangdong Province, China, a new Encyonema species, Encyonema chebalingense sp. nov., was discovered. Based on observations with light and scanning electron microscopy, a detailed morphological description of E. chebalingense is here presented. The main features of E. chebalingense include: conspicuously asymmetrical and dorsiventral, semielliptical to semielliptical–lanceolate valves, with a filiform raphe; dorsal margin clearly arched and ventral margin nearly straight or slightly concave; central area on the ventral side formed by 1–2 shorter central striae; and short tectullae projecting within the striae. The new species was compared with some similar species, all of which show similarities to E. chebalingense but differ in features such as dimensions, internal valve structure, stria density and valve shape. This genus is common and abundant in relatively clean waters, and other new species most likely will be recorded in the future from China.

Investigation on the Characteristics of a New Structure Brake Distribution Valve

Brake distribution valve is an important part of aircraft hydraulic systems. TO realize the integra-tion and lightweight design of conventional structure valves, this paper proposed a new type brake distribution valve that uses new structure of pressure reducing unit, overflow unit and embedded shuttle valve instead of the conventional valve structure. The new structure de-creases the weight and volume of the valve; reduces the influence of non-work zone and damping on valve performance; improves the control precision and dynamic performance of the brake distribution valve. Both of numerical simulation and model verification experiments of the entire valve demonstrate that the dynamic performance of the new type valve has been significantly improved on the premise of ensuring linear characteristics. The results of simula-tion show that the response time of the new structure valve is 33% shorter than that of the conventional structure valve in case of step response simulation; in case of sinusoidal re-sponse simulation, the tracking error of the valve reduces by nearly 5%.

Recent Patents on Valve Mechanism Device

Background: Valves are an important part of nuclear power plants and are the control equipment used in nuclear power plants. It can change the cross-section of the passage and the flow direction of the medium and has the functions of diversion, cutoff, overflow, and the like. Due to the earthquake, the valve leaks, which will cause a major nuclear accident, endangering people's lives and safety. Objective: The purpose of this study is to synthesize the existing valve devices, summarize and analyze the advantages and disadvantages of various devices from many literatures and patents, and solve some problems of existing valves. Methods: This article summarizes various patents of nuclear-grade valve devices and recent research progress. From the valve structure device, transmission device, a detection device, and finally to the valve test, the advantages and disadvantages of the valve are comprehensively analyzed. Results: By summarizing the characteristics of a large number of valve devices, and analyzing some problems existing in the valves, the outlook for the research and design of nuclear power valves was made, and the planning of the national nuclear power strategic goals and energy security were planned. Conclusion: Valve damage can cause serious safety accidents. The most common is valve leakage. Therefore, the safety and reliability of valves must be taken seriously. By improving the transmission of the valve, the problems of complicated valve structure and high cost are solved.

Our management in vascular Behçet patients with ascending aorta aneurysm: 6 years’ experience

Background: Ascending aortic involvement in Behçet’s disease is very rare, and often accompanied by aortic root dilatation. In cases with aortic valve insufficiency without valve structure impairment, valve-sparing surgery can be performed. This study aimed to investigate the mid-term results of patients with ascending aortic involvement and selected surgical procedures according to the valve structure among those vascular Behçets disease.Methods: A total of 13 Behçet’s disease with aortic involvement operated at our center from January 2012 to 2018 was retrospectively investigated. Bentall or david valve-sparing operations were preferred according to the aortic valve status. Postoperative echocardiography and computed tomography imaging was performed periodically for aortic valve competence and pseudoaneurysm formation.Results: Bentall procedure was performed in 7 (54%) patients, and 6 (46%) patients were undergone valve-sparing David procedure. Operative mortality was 7.7%, one patient died of major gastrointestinal bleeding 3 months after the operation. After 51±23 (ranged 23 to 94) months of follow-up, no other mortality occurred, overall survival rates were 84.6%, two patients had minimally aortic regurgitation and one patient had mild regurgitation in David procedure. In Bentall procedure, no paravalvular leakage was found during follow-up.Conclusions: The database of our retrospective study regarding age and sex incidence, clinicopathological features and therapeutic outcome was comparable to other studies in various literatures.

Частота и быстродействие спинового вентиля с планарной анизотропией слоев

The dynamics of the magnetization vector in the free layer of a layered spin-valve structure was simulated. As materials for the free and fixed layers, six magnetically soft ferromagnets with longitudinal anisotropy were considered. The types of magnetization dynamics that are of practical interest for MRAM and HMDD (switching of the magnetization vector), STNO (stable precession of the magnetization vector), and the base element PSL (switching of the magnetization vector with two probable outcomes) were highlighted. The ranges of currents and fields corresponding to these operating modes of the spin valve were calculated. The numerical calculations of the switching time showed that, among the considered materials for the MRAM cell, the most suitable is Co80Gd20 alloy, while for the HMDD read head, it is Fe60Co20B20. As a result of the precession frequency calculations, it was concluded that the Fe60Co20B20 alloy is optimal for the STNO ferromagnetic layers. For the implementation of PSL, the best switching characteristics were demonstrated by the Co93Gd7 alloy.