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Silicon carbide (SiC) is a high-performance structural ceramic material with excellent comprehensive properties unmatched by metals and other structural materials. In this paper, the raw SiC powder with an average grain size of 5 μm was sintered by an isothermal compression process at 5.0 GPa and 1500 °C, and the maximum hardness of the sintered samples is 31.3 GPa. Subsequently, scanning electron microscopy was used to observe the microscopic morphology of the recovered SiC samples treated in the temperature and extended pressure range of 0 - 1500 °C and 0 - 16.0 GPa, respectively. The defects and plastic deformation in SiC grains were further analyzed by transmission electron microscopy. Further, high pressure in situ synchrotron radiation x-ray diffraction was used to study the intergranular stress distribution and yield strength under non-hydrostatic compression. This study provides a new viewpoint for the sintering of pure phase micron sized SiC particles.

Objective This study aims to evaluate the accuracy of magnetic resonance imaging (MRI) in diagnosing orofacial clefts and proposes specific signs for determining the type of cleft. Methods Pregnant women in whom fetal facial malformations are suspected by ultrasonography (US) underwent 1.5 T MRI. The accuracy of the prenatal US and MRI diagnosis was compared with the postnatal findings. Results A total of 71 fetuses were included in the final analysis, which comprised of 35 cases of isolated cleft lip, six cases of cleft lip and alveolus, 21 cases of cleft lip and palate, four cases of isolated cleft palate, and five normal fetuses. MRI was more sensitive than US (MRI 100%, US 77.5%; Fisher's exact test: MRI vs US P=0.000). The accuracy of MRI for all types was 100%. Specific signs (Inverted T, L/anti-L, U, and "Notch" signs) were proposed, indicating the normal hard, unilateral cleft, bilateral cleft, and cleft soft palates, respectively, which can facilitate the identification of different types of cleft palates. Conclusion MRI can accurately diagnose the type of cleft based on typical signs, which can serve as a definite diagnostic modality and an effective supplement of US.

This postmortem magnetic resonance imaging (MRI) study of the fetal spine aimed to describe the timing of appearance, shape, volume, and relative positions of the S1–S3 costal element ossification centers (CEOCs). We obtained sagittal 3D dual-echo steady-state with water excitation T2 images of the entire spine in 71 fetuses (gestational ages (GAs), 17–42 weeks). Computed tomography and histological examinations were performed on two fetal specimens (GAs, 21 and 30 weeks) to validate the MR images. The presence/absence of each sacral CEOC was recorded according to the GA. CEOC volume was measured. We analyzed the CEOC position relative to the vertebral column and ilium. The S1, S2, and S3 CEOCs first appeared at 23, 22, and 29 weeks, respectively. The S1 and S2 CEOCs could be detected in all fetuses with GAs of ≥ 30 weeks and ≥ 35 weeks, respectively, while the S3 CEOCs were variably present until term. The percentages of detection of the S1 and S2 CEOCs were significantly greater than that of the S3 CEOCs at each GA. At S1 and S2, the CEOC volume increased exponentially with GA. The relative positions of the S1 and S2 CEOCs, but not the S3 CEOCs, significantly correlated with GA (P

Supplemental Digital Content is available in the text, Background: Colorectal cancer (CRC) is the third most common cancer in the world, with 694,000 deaths each year. Despite improvements in treatment strategies in recent years, the overall survival rate of CRC is still very low and the survival rate is highly dependent on the stage at the time of diagnosis. Some biomarkers have shown great potential for early screening of CRC and some have been tested in systematic reviews (SRs). However, the quality of these SRs remains unclear and these SRs did not clarify which biomarker is the optimal diagnostic test. This overview will evaluate the methodological quality of available SRs and compare the diagnostic value of different biomarkers in order to find the best biomarker for diagnosing CRC. Methods: A comprehensive literature search for SRs published before February 2019 was conducted in the PubMed, Embase.com, Cochrane Library, and Web of Science without any language restrictions. We will use the assessment of multiple systematic reviews-2 instrument to assess the methodological quality of each SR. Bubble plots will be used to summarize the main characteristics and quality of SRs. Standard pairwise meta-analysis and adjusted indirect comparison will be conducted to compare the diagnostic value of different biomarkers. Results: The results of this overview will be submitted to a peer-reviewed journal for publication. Conclusion: The findings of this project will provide a general overview and evidence of the diagnostic value of biomarkers in detecting CRC. PROSPERO registration number: CRD42019125880.

BACKGROUND: The high recurrence rate of hepatocellular carcinoma (HCC) after potentially curative treatment determines the long-term prognosis.OBJECTIVE: To evaluate the efficacy and safety of adjuvant therapies in patients with HCC who have undergone hepatic resection, transplantation or locoregional ablation therapy.METHODS: Several databases were searched to identify randomized controlled trials (RCTs) fulfilling the predefined selection criteria. Meta-analyses were performed to estimate the effects of adjuvant therapies of any modality on recurrence-free survival (RFS) and overall survival (OS).RESULTS: Eight adjuvant modalities were identified from 27 eligible RCTs conducted predominantly in Asian populations comparing adjuvant with no adjuvant therapy. Adjuvant chemotherapy, internal radiation and heparanase inhibitor PI-88 therapy failed to improve RFS or OS, while interferon (IFN) therapy yielded significant survival results. The findings of adjuvant vitamin analogue therapy required further examination. Adjuvant adoptive immunotherapy conferred significant benefit for RFS but not for OS. Although cancer vaccine therapy and radioimmunotherapy may improve survival after radical surgery, the results were from single, small-scale trials. Severe side effects were observed in the studies of adjuvant chemotherapy and of IFN therapy.CONCLUSIONS: Adjuvant IFN therapy can improve both RFS and OS; however, the benefits of using this agent should be weighed against its side effects. Combination of systemic and transhepatic arterial chemotherapy is not recommended for HCC after potentially curative treatment. Other adjuvant therapies produce limited success for survival. Additional RCTs with proper design are required to establish the role of adjuvant therapies for HCC.

An epidemic of severe acute respiratory syndrome (SARS) began in Foshan municipality, Guangdong Province, China, in November 2002. We studied SARS case reports through April 30, 2003, including data from case investigations and a case series analysis of index cases. A total of 1,454 clinically confirmed cases (and 55 deaths) occurred; the epidemic peak was in the first week of February 2003. Healthcare workers accounted for 24% of cases. Clinical signs and symptoms differed between children (18 years) and older persons (or =65 years). Several observations support the hypothesis of a wild animal origin for SARS. Cases apparently occurred independently in at least five different municipalities; early case-patients were more likely than later patients to report living near a produce market (odds ratio undefined; lower 95% confidence interval 2.39) but not near a farm; and 9 (39%) of 23 early patients, including 6 who lived or worked in Foshan, were food handlers with probable animal contact.

Sixty-one SARS coronavirus genomic sequences derived from the early, middle, and late phases of the severe acute respiratory syndrome (SARS) epidemic were analyzed together with two viral sequences from palm civets. Genotypes characteristic of each phase were discovered, and the earliest genotypes were similar to the animal SARS-like coronaviruses. Major deletions were observed in the Orf8 region of the genome, both at the start and the end of the epidemic. The neutral mutation rate of the viral genome was constant but the amino acid substitution rate of the coding sequences slowed during the course of the epidemic. The spike protein showed the strongest initial responses to positive selection pressures, followed by subsequent purifying selection and eventual stabilization.

Through theoretical analysis of thyristor switch, criterion of turn-off was derived for the design of thyristor switch. The expression of parameter design and its math model during the turn-off were deduced. The simulation and experiment have been accomplished to validate the analysis.

To investigate the natural infection of Angiostrongylus cantonensis in Guangdong Province, and to provide the scientific evidence for control measures.The investigation was carried out in 56 villages of 28 towns of 28 counties/districts in East Guangdong, West Guangdong, the mountain area of North Guangdong and Peal River Delta of the Province from 2005 to 2010. The rodents were captured with live trap and the species identified. Angiostrongylus cantonensis adult worms were collected from the hearts and lungs of rodents, examined, counted and the sex of worms identified.The rodents were captured from 2005 to 2010, belonged to 2 orders, 2 families (subfamily), 4 genera and 10 species. Seven species of the rodents were found infected with Angiostrongylus cantonensis in all 28 counties/districts. Totally 5 820 rats were examined and 496 infected ones were identified, with a mean infection rate of 8.52%. The infection rate of rodents was highest in the Peal River Delta, reaching 9.8% (205/2084) (chi2=15.25, P0.01). Rattus norvegicus had the highest infection rate of 16.9% (310/1 835) (chi2=240.91, P0.01). The mean intensity of infection was 6.1 worms/rat. 1 125 female and 1064 male worms were found respectively (chi2=1.75, P0.05).Natural infection of Angiostrongylus cantonensis in rodents has been found in all the 56 villages selected from the 4 regions of Guangdong Province.

The genomic sequences of severe acute respiratory syndrome coronaviruses from human and palm civet of the 2003/2004 outbreak in the city of Guangzhou, China, were nearly identical. Phylogenetic analysis suggested an independent viral invasion from animal to human in this new episode. Combining all existing data but excluding singletons, we identified 202 single-nucleotide variations. Among them, 17 are polymorphic in palm civets only. The ratio of nonsynonymous/synonymous nucleotide substitution in palm civets collected 1 yr apart from different geographic locations is very high, suggesting a rapid evolving process of viral proteins in civet as well, much like their adaptation in the human host in the early 2002–2003 epidemic. Major genetic variations in some critical genes, particularly the Spike gene, seemed essential for the transition from animal-to-human transmission to human-to-human transmission, which eventually caused the first severe acute respiratory syndrome outbreak of 2002/2003.

To analysis the risk factors influencing nosocomial infection of severe acute respiratory syndrome (SARS) in health-care workers and to evaluate effectiveness of its control and preventive measures in 13 key hospitals caring for SARS patients.Number of SARS patients, clinical conditions of them, its attack rate in health-care workers, and characteristics of hospitals, including their environment, isolating measures, etc. were investigated at the 13 hospital in Guangzhou to analyze the risk factors influencing nosocomial infection of SARS and its attack rates in health-care workers before and after implementation of preventive measures and to evaluate their effectiveness.Totally, 841 patients with SARS were treated at the 13 hospitals in Guangzhou and 285 health-care workers caring for them infected nosocomially. Attack rate in health-care workers was higher at general hospitals, hospital accepting more cases in critical conditions and hospitals with poor precautious measures, and lower in hospitals with isolated wards or areas, or department of infection, specially caring for SARS patients, and those with effective intervention measures to prevent secondary infection.Nosocomial infection of SARS in health-care workers was affected by clinical condition of SARS patients, characteristics and environment of hospitals and their personal protective measures adopted.

To evaluate the effectiveness of personal protective measures of health care workers (HCWs) against severe acute respiratory syndrome (SARS).A case-control study from ten hospitals in Guangdong, with 180 non-infected and 77 infected staff members that accessed the isolation unit every day, and participated in direct first aid for severe SARS patients. All participants were surveyed about how they were using personal protective equipment (PPE), protective drugs and hygiene habits when caring for patients with SARS. Statistical analysis was done with either chi(2) or Fisher's exact test for univariate analysis, whereas we used forward stepwise selection (Waldesian) for logistic regression.Univariate analysis showed that mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting", gargle, "membrane protection", "taking shower and changing clothing after work", "avoid from eating and drinking in ward", oseltamivir phospha tall had protective effects (P0.05), but stepwise logistic regression showed significant differences for mask (OR = 0.78, 95% CI: 0.60 - 0.99), goggles (OR = 0.20, 95% CI: 0.10 - 0.41) and footwear (OR = 0.58, 95% CI: 0.39 - 0.86). Analysis for linear trend in proportions showed that dose response relationship existed in mask, gown, gloves, goggles, footwear, gargle, "membrane protection" and "taking shower and changing dree after work" (P0.01). The attack rate of HCWs who were rescuing severe SARS patients without any PPE was 61.5% (16/26). It seemed that the more the protective measures were used, the higher the protective effect was (P0.001), and could reach 100% if mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting" were all used at the same time.Nosocomial infection of SARS can be prevented effectively by precautions against droplets and personal contact. HCWs must take strict protection according to the guidance of WHO or Chinese MOH and pay attention to personal hygiene.

To explore epidemiological features and risk factors of severe acute respiratory syndrome (SARS) in Guangdong Province of China, so as to work out effective strategies for its better control.A total of 1 511 clinically confirmed SARS cases in Guangdong Province of China from November 16, 2002 to Jun 15, 2003 were retrospectively analyzed.The first SARS case was identified in Foshan municipality on November 16, 2002, followed by 1 511 clinically confirmed cases (including 58 deaths) up to May 15, 2003. Of all cases, health care workers and community family cluster cases accounted for 19.38% and 12.04%. 65.86% SARS patients aged 20 - 49 years, and increased incidence was positively related to their ages. 95.97% cases lived in the following five cities around Pearl Delta Area: Foshan, Guangzhou, Shenzhen, Zhongshan, and Jiangmen. Eleven early reported cases in the communities took animal-related positions. Face-to-face contacts with infected droplets were the main transmission route. An epidemic peak occurred during January 28 to February 26, and those cases accounted for 50.69% of total. Incidence, mortality, and case fatality of SARS were 1.77/100,000, 0.07/100,000, and 3.84% respectively. The mean incubation period was 4.5 days.The most effective way to control SARS is to break the chain of transmission from infected to healthy persons-early identification, prompt and effective isolation, and vigorous close contact tracing. Hospital infections among health care workers is critical. Several observations support the hypothesis of an animal origin for the disease.

To analyze the epidemiological features of the index cases of severe acute respiratory syndrome (SARS) occurred in different cities in Guangdong province and to trace for the source of infection.Standardized individual case inventory was adopted to conduct investigation on index cases and on persons who had close contact with index cases in Guangdong province. Data on the epidemiological characteristics, secondary cases and the links among index cases were analyzed.Between November 16, 2002 and April 16, 2003, there had been 13 index cases of SARS including 3 cadres, 3 farmers, 2 retirees, 2 workers and 1 shop attendant, reported from 13 cities in Guangdong province. Between November 2002 and January 2003, there had been 7 cities reported to have identified index cases of SARS with 6 of them being infected in their own cities and 1 imported from Guangzhou city. All of the cases had no close contacts to similar patients but 6 of them later caused 2nd or even 3rd generation cases of SARS. Most cases hit young people (7/13) with a sex ratio of 1:0.6. The fatality rate of index cases was high (4/13).No evidence showed that there was direct transmission among the index cases. Data regarding the geographical origin of those index cases led to the assumption that the infection had started in six cities of Pearl river delta region and the Hong Kong Special Administrative Region.

To understand the epidemiological characteristics of severe acute respiratory syndrome (SARS) outbreaks in some areas of Guangdong province and to provide scientific basis for prevention and control measures against it.Standardized questionnaire was used on individual cases. Data on the epidemiological characteristics as time, place, persons and aggregation status of SARS cases, development of the epidemics, were analyzed with software EPI 6.0.The incidence of SARS in Guangdong province was 1.72/100,000 with case fatality rate as 3.64%. Most cases of SARS occurred between the last ten days of January and the first ten days of February with the peak (61.88% of the patients) occurred in the first ten days of February. As to the distribution of place, Pearl river delta region-economically developed with great number of mobile population-was heavily affected areas (account for 96.66% of the total patients). The majority of patients were young adults and medical staff seemed to be the most affected subgroup (account for 24.9% of the patients in total). Family and hospital aggregation of patients comprised the another two important characteristics of SARS (account for 37.1% of the total patients).Current knowledge on SARS suggested that it was an air-borne infectious disease with human beings served as the source of infection. The incubation period of the disease was from 1 to 12 days with a median of 4 days. Respiratory secretions and close contact contributed to person-to-person transmission. Most cases were distributed in Pearl river delta region, an area famous for its economic development and heavy flow of mobile population.