一种变细分数的3D打印步进电机控制方法

步进电机作为3D打印机上的主要执行元件,其运行速度对打印效率有着重要的影响。现有的定细分数3D打印步进电机控制方法在追求高精度打印的同时往往会牺牲打印速度,为了解决这一问题,提出了一种变细分数的3D打印步进电机控制方法,即大距离范围内采用低细分数,以提升运行速度,在小距离范围内采用高细分数,以保证打印精度。搭建了仿真模型和实验系统,结果表明:提出的变细分数控制方法在保证打印精度的同时提高了打印速度,验证了该方法的可行性与有效性。

用89C52单片机实现反应式步进电机变细分驱动

介绍采用89C52单片机实现高可靠性低成本的反应式步进电机变细分驱动的方法,包括如何利用89C52单片机控制的步进电机恒转矩、斩波恒流、细分驱动方案及技术要点。

多步进电机的变细分加减速控制研究

对两相混合式步进电机的各种加减速控制方法进行了比较分析,针对舞台灯的应用场合,提出并采用多步进电机的变细分加减速控制方法,解决了单一单片机控制步进电机的数量与速度的矛盾。

基于DPRNN语音分离的变时长型S-T课堂教学分析法

在教育智能信息化的大环境下,智能且自动的教学评价体系必不可少,课堂教学分析是教育评价领域的重要环节。本文针对课堂教学分析问题,提出一种利用DPRNN分离课堂音频并使用S-T分析法进行分析的方法。该方法以DPRNN为基础,获取较精确的教师音频,通过平均细分变时长编码法对音频进行S-T编码处理。相比基于视频的传统的S-T分析法,该方法具有成本低、方便处理、具有时间不变性及准确性较高等优点。

Computer aided stitching approach for dental restoration models

According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.

Fine Mapping of AST Gene in Arabidopsis

The ast ( anthocyanin spotted testa) mutant, which was induced by carbon ion radiation, was a single recessive gene mutant of Arabidopsis thaliana (L.) Heynh. with spotted pigment in seed coats, and involved in the anthocyanin biosynthesis. To clone the AST gene by map-based cloning strategy, a series of molecular markers were designed according to the SNPs (single nucleotide polymophisms) and insertion/deletion polymophisms in the Arabidopsis database. With these molecular markers, the fine-structure mapping of the AST gene was finished, the AST locus was located in BAC clone T13M11. It was suggested that the AST candidate gene was T13M11. 8 in the T13M11 This gene was 1432 bp long with 6 exons and 5 introns. The putative protein of T13M11. 8 gene was similar to dihydroflavonol 4-reductase (DFR), which was an important enzyme in the anthocyanin biosynthesis pathway.

Meso-mechanical analyses of shape memory alloy wires reinforced smart structures with damages

The thermo-mechanical behaviors of shape memory alloy (SMA) wires reinforced smart structures with damages are analyzed through variational principle and meso-mechanical method.A governing equation on the structure is derived.Mathematical expressions on meso-displacement field,stress-strain field of typical element with damages are presented.A failure criterion for interface failure between SMA wires and matrix is established under two kinds of actuation which are dead-load and temperature,where the temperature is included in effective free restoring strain.In addition,there are some other composing factors in the failure criterion such as interface properties,thermodynamical properties of SMA,initial debonding length L-l,etc.The results are significant to understand structural strength self-adaptive control and failure mechanism of SMA wires reinforced smart structures with damages,and provide a theoretical foundation for further study on the integrity of SMA smart structures.

Maintenance of radiation-induced intestinal fibrosis:Cellular and molecular features

Recent advances in cell and molecular radiobiology clearly showed that tissue response to radiation injury cannot be restricted to a simple cell-killing process, but depends upon continuous and integrated pathogenic processes, involving cell differentiation and crosstalk between the various cellular components of the tissue within the extracellular matrix. Thus, the prior concept of primary cell target in which a single-cell type （whatever it＇s epithelial or endothelial cells） dictates the whole tissue response to radiation injury has to be replaced by the occurrence of coordinated multicellular response that may either lead to tissue recovery or to sequel development. In this context, the present review will focus on the maintenance of the radiation-induced wound healing and fibrogenic signals triggered by and through the microenvironment toward the mesenchymal cell compartment, and will highlight how sequential and sustained modifications in cell phenotypes will in cascade modify ceU-to-ceU interactions and tissue composition.

INDIVIDUAL COMMUNICATION TRANSMITTER IDENTIFICATION BASED ON MULTIFRACTAL ANALYSIS

In this letter, the communication transmitter transient signals are analyzed based on the time-variant hierarchy exponents of multifractal analysis. The species of optimized sample set is selected as the template of transmitter identification, so that the individual communication transmitter identification can be realized. The turn-on signals of four transmitters are used in the simulation. The experimental results show that the multifractal character of transmitter transient signals is an effective character of individual transmitter identification.

Clear cell adenocarcinoma of the colon is a unique morphological variant of intestinal carcinoma:Case report with molecular analysis

Here we report a new case of clear cell adenocarcinoma (CCA) of the colon in a 54-year-old Caucasian man. Despite of the previous reported cases, the lesion was located in the right colon and was not associated with the conventional adenoma. We performed immunohistochemical and molecular analyses in order to explore whether the CCA had the molecular features generally associated with conventional colorectal carcinoma. The immunohistochemical and molecular analyses showed that the different morphology of CCA does not reflect a distinct biological entity but only an unusual morphological variant of intestinal carcinoma.

Multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated hepatocellular carcinoma in a patient with alcohol-related liver cirrhosis

We describe a rare case of the transformation of a dysplastic nodule into well-differentiated hepato- cellular carcinoma (HCC) in a 56-year-old man with alcoholrelated liver cirrhosis. Ultrasound (US) disclosed a 10 mm hypoechoic nodule and contrast enhanced US revealed a hypovascular nodule, both in segment seven. US-guided biopsy revealed a high-grade dysplastic nodule characterized by enhanced cellularity with a high N/C ratio, increased cytoplasmic eosinophilia, and slight cell atypia. One year later, the US pattern of the nodule changed from hypoechoic to hyperechoic without any change in size or hypovascularity. US-guided biopsy revealed well-differentiated HCC of the same features as shown in the first biopsy, but with additional pseudoglandular formation and moderate cell atypia. Moreover, immunohistochemical staining of cyclase- associated protein 2, a new molecular marker of well- differentiated HCC, turned positive. This is the first case of multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated HCC within one year in alcohol-related liver cirrhosis.

Molecular and in vitro Characterization of Field Isolates of Bovine Herpesvirus-1

Bovine Herpesvirus-1 (BoHV-1) is distributed worldwide and is a major pathogen in cattle, being the causal agent of a variety of clinical syndromes. The aim of this study was to isolate and to characterize (molecular and biological characterization) BoHV-1 from 29 immunosuppressed animals. It was possible to obtain 18 isolates, each from a different animal, such as from the respiratory and reproductive tracts. In some cases the cytopathic effect was visible 12 hours post-inoculation, and became characteristic after 36-48 hours. Biological characteristics were evaluated and compared with Iowa and Colorado-1 reference strains, and differences were found in plaque size, virus titer measured by TCID50 and PFU/mL, and one step virus curves. These results showed that some isolates had a highly virulent-like behavior in vitro, compared to the reference strains, with shorter eclipse periods, faster release of virus into the supernatants, and higher burst size and viral titer. There were no differences in glycoprotein expression of BoHV-1 isolates, measured by Western blot on monolayers. Moreover, using restriction endonucleases analysis, most of the viruses were confirmed as BoHV-1.1 and just one of them was confirmed as BoHV-1.2a subtype. These findings suggest that some wild-type BoHV-1 isolates could be useful as seeds to develop new monovalent vaccines.

Properties inhomogeneity of AM60 magnesium alloy processed by cyclic extrusion compression angular pressing followed by extrusion

A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is presented.In this process,a cyclic extrusion compression angular pressing(CECAP)process is followed by an extrusion step in the outlet playing the role of additional back pressure.Therefore,more uniform and enhanced mechanical properties are expected in comparison with equal channel angular pressing(ECAP).In order to evaluate the effectiveness and capabilities of this new method,an AM60 magnesium alloy was processed.Finite element results exhibited a significant increase in strain values as well as uniform strain distribution for the new method.In addition,~110%increase in compressive stress was observed in new method compared to the conventional ECAP.Experimental results revealed a noticeable increase in the hardness and strength of the specimens processed by the new technique as a result of the formation of finer grains and more homogeneous microstructure with good distribution of refinedβ-phase along the boundaries.It may be concluded that the new process is very promising for future magnesium alloy products.

Analysis of Unstable Chromosome Aberrations in Simulation of Partial Body Exposures with Gamma Rays

Accidentally or occupationally exposures to ionizing radiation generally involving the partial-body exposures and this may pose significant health hazards that are indicated by chromosome aberration （CA） induction. In this experiment, the quantification of the frequencies of CA was carried out based on cytogenetic analyses of peripheral blood samples obtained from 4 healthy volunteers as a result of simulation of partial-body exposures. The percentages of mixtures of blood samples irradiated in vitro with 2 Gy of gamma rays were 10, 25, 50, 75 and 100.0%. Lymphocytes were cultured and first-division metaphase cells were collected after culture times of 48 h and then harvested with standard procedures. The results showed that frequencies of unstable CA were depended on the percentage/portion of irradiated blood. All frequencies of observed CA was lower than that of calculated from 100% exposed blood, except in one case, indicating a phenomena of＂dilution＂ of unirradiated into irradiated lymphocytes though there could be a bystander effects taken place. The increasing in frequency for 25-100% portions was also comparable with other similar experiments. The quantification of CAs in lymphocytes is an important methodology of dose assessment for partial-body exposure to ionizing radiation, however, the scenario of exposure should be determined.

Efficacy analysis and multi-factor retrospective study of third-line chemotherapy in 82 Chinese patients with small cell lung cancer

Objective As there is currently no clear recommendation for third-line chemotherapy for small cell lung cancer （SCLC）, its efficacy is unknown. To date, there have rarely been reports of Chinese patients with SCLC who received third-line chemotherapy. Therefore, we investigated the efficacy, safety, and prognostic factors of Chinese patients with SCLC treated with third-line chemotherapy. Methods A retrospective analysis of patients with SCLC who received third-line chemotherapy was performed. Results Between 2007 and 2013, 62 patients [62 men （75.6%）, 20 women （24.4%）; median age at the time of diagnosis, 55 years] received third-line chemotherapy at our center. Of these patients, 44 had limited-stage disease and 38 had extensive-stage disease. On third-line chemotherapy, 55 （67.1%） patients had an Eastern Cooperative Oncology Group performance status （ECOG PS） of 0-1, objective response rate of 15.9%, and median overall survival after third-line chemotherapy （OS-3） and median progres- sion-free survival after third-line chemotherapy （PFS-3） of 5.6 months and 3.0 months, respectively. On univariate analysis, PFS-3 was significantly related with ECOG PS （P = 0.005）, response to second-line chemotherapy （P = 0.002）, response to third-line chemotherapy （P 〈 0.001）, and PFS after second-line chemotherapy （P = 0.026）. OS-3 was significantly related with ECOG PS （P 〈 0.001）, response to third-line chemotherapy （P = 0.033）, PFS after first-line therapy （P = 0.044）, and PFS after second-line therapy （PFS-2） （P = 0.007）. On multivariate analysis, ECOG PS （P = 0.008） and response to third-line chemotherapy （P = 0.046） were independent prognostic factors for PFS-3, while ECOG PS （P = 0.007） and PFS-2 （P 〈 0.001） were independent prognostic factors for OS-3. Conclusion Few patients with SCLC receive third-line chemotherapy. Our findings suggest that patients with an ECOG PS 0-1 and PFS-2 for 〉3 months will be benefit from third-line chemotherapy, which should be actively offered to them.

Surgicopathological classification of hepatic space-occupying lesions:A single-center experience with literature review

Accompanying rapid developments in hepatic surgery,the number of surgeries and identifications of histological types of primary hepatic space-occupying lesions (PHSOLs) have increased dramatically.This has led to many changes in the surgicopathological spectrum of PHSOLs,and has contributed to a theoretical basis for modern hepatic surgery and oncological pathology.Between 1982 and 2009 at the Eastern Hepatobiliary Surgery Hospital (EHBH) in Shanghai,31 901 patients underwent surgery and were diagnosed as having a PHSOL.In this paper,we present an analysis of the PHSOL cases at the EHBH for this time period,along with results from a systematic literature review.We describe a surgicopathological spectrum comprising more than 100 types of PHSOLs that can be stratified into three types:tumor-like,benign,and malignant.We also stratified the PHSOLs into six subtypes derived from hepatocytes;cholangiocytes;vascular,lymphoid and hemopoietic tissues;muscular,fibrous and adipose tissues;neural and neuroendocrine tissues;and miscellaneous tissues.The present study provides a new classification system that can be used as a current reference for clinicians and pathologists to make correct diagnoses and differential diagnoses among various PHSOLs.

Fine analysis on advanced detection of transient electromagnetic method

Fault fracture zones and water-bearing bodies in front of the driving head are the main disasters in mine laneways,thus it is important to perform their advanced detection and prediction in advance in order to provide reliable technical support for the excavation.Based on the electromagnetic induction theory,we analyzed the characteristics of primary and secondary fields with a positive and negative wave form of current,proposed the fine processing of the advanced detection with variation rate of apparent resistivity and introduced in detail the computational formulae and procedures.The result of physical simulation experiments illustrate that the tectonic interface of modules can be judged by first-order rate of apparent resistivity with a boundary error of 5%,and the position of water body determined by the fine analysis method agrees well with the result of borehole drilling.This shows that in terms of distinguishing structure and aqueous anomalies,the first-order rate of apparent resistivity is more sensitive than the secondorder rate of apparent resistivity.However,some remaining problems are suggested for future solutions.

Hepatocellular carcinoma in Egypt: A single center study over a decade

AIM： To identify the trend, possible risk factors and any pattern change of hepatocellular carcinoma （HCC） in Egypt over a decade. METHODS： All HCC patients attending Cairo Liver Center between January 1993 and December 2002, were enrolled in the study. Diagnosis of HCC was based on histopathological examination and/or detection of hepatic focal lesions by two imaging techniques plus α-fetoprotein level above 200 ng/mL. The duration of the study was divided into two periods of 5 years each; period Ⅰ （1993-1997） and period Ⅱ （1998-2002）. Trend, demographic features of patients （age, gender, and residence）, risk factors （HBsAg, HCV-Ab, schistosomiasis and others） and pattern of the focal lesions were compared between the two periods. Logistic regression model was fitted to calculate the adjusted odds ratios for the potential risk factors. The population attributable risk percentage was calculated to estimate the proportion of HCC attributed to hepatitis B and C viral infections. RESULTS： Over a decade, 1 328 HCC patients out of 22 450 chronic liver disease （CLD） patients were diagnosed with an overall proportion of 5.9%. The annual proportion of HCC showed a significant rising trend from 4.0% in 1993 to 7.2% in 2002 （P = 0.000）. A significant increase in male proportion from 82.5% to 87.6% （P = 0.009）; M/F from 5：1 to 7：1 and a slight increase of the predominant age group （40-59 years） from 62.6% to 66.8% （P = 0.387）in periods Ⅰ and Ⅱ respectively, reflecting a shift to younger age group. In the bivariate analysis, HCC was significantly higher in rural residents, patients with history of schistosomiasis and/or blood transfusion. Yet, after adjustment, these variables did not have a significant risk for development of HCC. There was a significant decline of HBsAg from 38.6% to 20.5% （P = 0.000）, and a slight increase of HCV-Ab from 85.6% to 87.9% in periods I and II respectively. HBV conferred a higher risk to develop HCC more than HCV in period Ⅰ （OR 1.9 vsl.6） and period Ⅱ （OR 2.7 vs 2.0）, but the relative contribution of HBV for development of HCC declined in period Ⅱ compared to period Ⅰ （PAR% 4.2%, 21.32%）. At presentation, diagnostic α-fetoprotein level （≥200 ng/mL） was demonstrated in 15.6% vs28.9% and small HCC （≤3 cm） represented 14,9% vs 22,7% （P = 0,0002） in periods Ⅰ and Ⅱ respectively. CONCLUSION： Over a decade, there was neady a twofold increase of the proportion of HCC among CLD patients in Egypt with a significant decline of HBV and slight increase of HCV as risk factors. α-Fetoprotein played a limited role in diagnosis of HCC, compared to imaging techniques. Increased detection of small lesions at presentation reflects increased awareness of the condition.

Molecular landscape in acute myeloid leukemia: where do we stand in 2016

Acute myeloid leukemia(AML) is a clonal disorder characterized by the accumulation of complex genomic alterations that define the disease pathophysiology and overall outcome. Recent advances in sequencing technologies have described the molecular landscape of AML and identified several somatic alterations that impact overall survival. Despite all these advancement, several challenges remain in translating this information into effective therapy. Herein we will review the molecular landscape of AML and discuss the impact of the most common somatic mutations on disease biology and outcome.

A Comparative Study of Intensive Litopenaeus vannamei Culture on Four Bottom Substrates Without Water Change

The effect of four bottom substrates, oyster shell powder(OP), sugarcane bagasse(SB), a mixture of OP and SB(OS) and fresh soil(FS), on the water quality and bacterial and zooplankton density of intensive shrimp(Litopenaeus vannamei) culture tanks without water change and the growth performance of cultured shrimp were compared in this study. At the end of a 110 days culturing trial, the total ammonium-N(TAN) of the water on SB and the nitrite nitrogen(NO2-N) on OS was significantly lower than that on the other substrates(P<0.05), which coincided with the high density of ammonium- and nitrite-oxidizing bacteria in the water on SB and OS, respectively. The concentration of chlorophyll a(Chl a) increased slowly on OP, SB and OS but remained low on FS. The density of total bacteria on OP, SB and OS was one order of magnitude higher than that on FS, and the density of zooplankton on SB and OS was significantly higher than that on FS or OP(P<0.05). The improved water quality and increased density of bacteria and zooplankton on SB and OS may have had a synergistic effect on shrimp culture, improving its growth performance(high survival rate and yield and low feed conversion rate). SB and OS were more effective for improving the growth performance of intensively cultured L. vannamei without water change than OP and FS. To our knowledge, this study presents the first evidence regarding the effect of different bottom substrates on intensive shrimp culture.