核苷酸类物质的应用研究进展

核苷酸类物质包括腺苷酸、尿苷酸、鸟苷酸、胞苷酸等及其衍生物,是生物体内一种极其重要的低分子化合物,具有十分广泛的用途。已在医药、食品、保健、农业、化妆品中得到了广泛的应用,本文综述了核苷酸类物质应用方面的研究进展。     

Integrated OMICs Approach for the Group 1 Protease Mite-Allergen of House Dust Mite Dermatophagoides microceras

House dust mites (HDMs) are one of the most important allergy-causing agents of asthma. In central Taiwan, the prevalence of sensitization to Dermatophagoides microceras (Der m), a particular mite species of HDMs, is approximately 80% and is related to the IgE crossing reactivity of Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f). Integrated OMICs examination was used to identify and characterize the specific group 1 mite-allergic component (Der m 1). De novo draft genomic assembly and comparative genome analysis predicted that the full-length Der m 1 allergen gene is 321 amino acids in silico. Proteomics verified this result, and its recombinant protein production implicated the cysteine protease and α chain of fibrinogen proteolytic activity. In the sensitized mice, pathophysiological features and increased neutrophils accumulation were evident in the lung tissues and BALF with the combination of Der m 1 and 2 inhalation, respectively. Principal component analysis (PCA) of mice cytokines revealed that the cytokine profiles of the allergen-sensitized mice model with combined Der m 1 and 2 were similar to those with Der m 2 alone but differed from those with Der m 1 alone. Regarding the possible sensitizing roles of Der m 1 in the cells, the fibrinogen cleavage products (FCPs) derived from combined Der m 1 and Der m 2 induced the expression of pro-inflammatory cytokines IL-6 and IL-8 in human bronchial epithelium cells. Der m 1 biologically functions as a cysteine protease and contributes to the α chain of fibrinogen digestion in vitro. The combination of Der m 1 and 2 could induce similar cytokines expression patterns to Der m 2 in mice, and the FCPs derived from Der m 1 has a synergistic effect with Der m 2 to induce the expression of pro-inflammatory cytokines in human bronchial epithelium cells.     

单相大容量核电变压器漏磁场及局部过热研究

本文中作者对单相超大容量核电变压器由漏磁产生的损耗和结构件温升计算方法进行了研究,通过实测值和计算值的对比,验证了本文提出的计算方法的正确性。     

Heat shock treatment decreases the mortality of sepsis in rats

Sepsis is an increasingly common and lethal diagnosis in hospitalized patients. In spite of the advances in antibiotics and medical equipment, the mortality rate has not been improved in the last decade. Recently, heat shock proteins (Hsps) have been well documented to play a self-protective role in almost all living cells under various pathological and physiological stresses through a mechanism known as thermotolerance or cross tolerance. The present study was designed to investigate the expression of Hsp72 and the protective role of pre-induction of Hsps in the mortality during different phases of sepsis. Adult male Sprague-Dawley rats were employed in the study. Sepsis was induced by cecal ligation and puncture (CLP). Heat shock treatment was performed 16 hrs before sepsis induction by heating the rats whole-bodily with an electric heating pad under general anesthesia. The mortality rates with time in both control and preheated groups were monitored. Hsp72 was detected by SDS-PAGE, Western blotting and immunostaining in the brain, heart, liver, kidney, lung, adrenal gland, muscle and lymphocytes. The results show that both early (9 hrs post-CLP) and late (18 hrs post-CLP) sepsis failed to increase the synthesis of Hsp72. Previous induction of Hsps by heat shock treatment significantly decreased the mortality rate of late sepsis. Applying a sufficient inducer to lymphocytes of late sepsis reversed the synthesis of Hsp72 from inactive state into an over-expressive situation in vitro. These results suggest that Hsps are involved in the pathogenesis of sepsis and the involvement of Hsps during the progression of sepsis could add to a first line of host defense against invasive pathogens. Searching for an acceptable agent or less invasive method that leads to increased Hsps expression may provide a means for better treatment of severe infection.     

Association of hiatus hernia with asplenia syndrome

During a 13-month period, 13 patients with asplenia syndrome were evaluated with MRI for cardiovascular and visceral anomalies. The MR images were reviewed for the presence of haitus hernia which was found in three patients. One of the remaining ten patients with no MRI evidence of hiatus hernia was diagnosed as having gastro-oesophageal reflux and hiatus hernia by an oesophagogram and 24-h pH monitoring. This patient had undergone fundoplication prior to MRI. Out of the 13 patients (31%) with asplenia syndrome, 4 had hiatus hernia. It appears that among patients with the asplenia syndrome, hiatus hernia is a frequent finding. Recurrent pneumonia or bronchiolitis in patients with asplenia syndrome requires evaluation for the presence of hiatus hernia and gastro-oesophageal reflux.     

The optical second-harmonic generation from porous silicon

Second-harmonic generation from porous silicon with a magnitude of two orders greater than that from the original silicon crystalline wafers is discussed. The measured effective second-order nonlinear susceptibility X⁽²⁾_ps.eff for a p-type porous silicon is 1.96×10^-7 esu. The susceptibility is estimated on the base of a bulk property rather than on quantum confinement owing to its large surface to volume ratio     

The anatomy of the tunica albuginea in the normal penis and Peyronie's disease

PURPOSE: We studied the fine architecture of the tunica albuginea of the penis. MATERIALS AND METHODS: The study included 6 human male cadavers and 10 surgical patients (5 with Peyronie's disease and 5 with normal penile anatomy). RESULTS: The tunica albuginea of the corpora cavernosa is a bi-layered structure with multiple sub layers. Inner layer bundles support and contain the cavernous tissue and are oriented circularly. Radiating from this layer are intracavernous pillars acting as struts, which augment the septum and provide essential support to the erectile tissue. Outer layer bundles are oriented longitudinally. These fibers extend from the glans penis to the proximal crura, where they insert into the inferior pubic ramus. There are no outer layer fibers between the 5 and 7 o'clock positions. Elastic fibers normally form an irregularly latticed network on which collagen fibers rest. In Peyronie's disease the well ordered appearance of the collagen layers is lost: excessive deposits of collagen, disordered elastic fibers and fibrin are found within the region of the plaque. CONCLUSIONS: The normal 3-dimensional structure of the tunica affords great flexibility, rigidity and tissue strength to the penis, which are lost consequent to structural changes in Peyronie's disease.     

Path planning for robobt manipulators in polyhhedral objects environment

A recent development in robotics is the increase of intelligence in robots. One of the research fields is to enable robots to autonomously avoid collisions with surrounding objects. This article presents an efficient method for planning collision-free paths for an articulated robot that is surrounded by polyhedral objects. The algorithm plans a hypothetical Archimedes's spiral path from the initial position to the goal position. When a collision among the arms and obstacles is detected, the hypothetical path will be modified to avoid the collision. The algorithm applies geometric methods to determine the upper and lower bounds of the reachable area of the wrist and then determines a collision-free path point on that reachable area. Because the equations, which represent the upper and lower bounds, are simple, the algorithm can rapidly determine a collision-free path. Moreover, with minor modifications, this path planning algorithm can also be applied to other robots such as spherical, cylindrical, and Cartesian types of robots. © 1995 John Wiley & Sons, Inc.     

PdTe2 Transition‐Metal Dichalcogenide: Chemical Reactivity,Thermal Stability,and Device Implementation

Palladium ditelluride (PdTe₂) is a novel transition‐metal dichalcogenide exhibiting type‐II Dirac fermions and topological superconductivity. To assess its potential in technology, its chemical and thermal stability is investigated by means of surface‐science techniques, complemented by density functional theory, with successive implementation in electronics, specifically in a millimeter‐wave receiver. While water adsorption is energetically unfavorable at room temperature, due to a differential Gibbs free energy of ≈+12 kJ mol^?1, the presence of Te vacancies makes PdTe₂ surfaces unstable toward surface oxidation with the emergence of a TeO₂ skin, whose thickness remains sub‐nanometric even after one year in air. Correspondingly, the measured photocurrent of PdTe₂‐based optoelectronic devices shows negligible changes (below 4%) in a timescale of one month, thus excluding the need of encapsulation in the nanofabrication process. Remarkably, the responsivity of a PdTe₂‐based millimeter‐wave receiver is 13 and 21 times higher than similar devices based on black phosphorus and graphene in the same operational conditions, respectively. It is also discovered that pristine PdTe₂ is thermally stable in a temperature range extending even above 500 K, thus paving the way toward PdTe₂‐based high‐temperature electronics. Finally, it is shown that the TeO₂ skin, formed upon air exposure, can be removed by thermal reduction via heating in vacuum.     

PtTe2‐Based Type‐II Dirac Semimetal and Its van der Waals Heterostructure for Sensitive Room Temperature Terahertz Photodetection

Recent years have witnessed rapid progresses made in the photoelectric performance of two‐dimensional materials represented by graphene, black phosphorus, and transition metal dichalcogenides. Despite significant efforts, a photodetection technique capable for longer wavelength, higher working temperature as well as fast responsivity, is still facing huge challenges due to a lack of best among bandgap, dark current, and absorption ability. Exploring topological materials with nontrivial band transport leads to peculiar properties of quantized phenomena such as chiral anomaly, and magnetic‐optical effect, which enables a novel feasibility for an advanced optoelectronic device working at longer wavelength. In this work, the direct generation of photocurrent at low energy terahertz (THz) band at room temperature is implemented in a planar metal–PtTe₂–metal structure. The results show that the THz photodetector based on PtTe₂ with bow‐tie‐type planar contacts possesses a high photoresponsivity (1.6 A W^?1 without bias voltage) with a response time less than 20 µs, while the PtTe₂–graphene heterostructure‐based detector can reach responsivity above 1.4 kV W^?1 and a response time shorter than 9 µs. Remarkably, it is already exploitable for large area imaging applications. These results suggest that topological semimetals such as PtTe₂ can be ideal materials for implementation in a high‐performing photodetection system at THz band.