Efficient passivation of n-type and p-type silicon surface defects by hydrogen sulfide gas reaction.

An efficient surface defect passivation is observed by reacting clean Si in a dilute hydrogen sulfide-argon gas mixture (<5% H2S in Ar) for both n-type and p-type Si wafers with planar and textured surfaces. Surface recombination velocities of 1.5 and 8 cm s-1are achieved on n-type and p-type Si wafers, respectively, at an optimum reaction temperature of 550 °C that are comparable to the best surface passivation quality used in high efficiency Si solar cells. Surface chemical analysis using x-ray photoelectron spectroscopy shows that sulfur is primarily bonded in a sulfide environment, and synchrotron-based soft x-ray emission spectroscopy of the adsorbed sulfur atoms suggests the formation of S-Si bonds. The sulfur surface passivation layer is unstable in air, attributed to surface oxide formation and a simultaneous decrease of sulfide bonds. However, the passivation can be stabilized by a low-temperature (300 °C) deposited amorphous silicon nitride (a-Si:NX:H) capping layer.

Colorectal stenting in England: a cross-sectional study of practice.

INTRODUCTION: UK and European guidelines recommend consideration of a self-expandable metallic stent (SEMS) as an alternative to emergency surgery in left-sided colonic obstruction. However, there is no clear consensus on stenting owing to concern for complications and long-term outcomes. Our study is the first to explore SEMS provision across England. METHODS: All colorectal surgery department leads in England were contacted in 2018 and invited to complete an objective multiple choice questionnaire pertaining to service provision of colorectal stenting (including referrals, time, location and specialty). RESULTS: Of 182 hospitals contacted, 79 responded (24 teaching hospitals, 55 district general hospitals). All hospitals considered stenting, with 92% performing stenting and the remainder referring. The majority (93%) performed fewer than four stenting procedures per month. Most (96%) stented during normal weekday hours, with only 25% stenting out of hours and 23% at weekends. Compared with district general hospitals, a higher proportion of teaching hospitals stented out of hours and at weekends. Stenting was performed in the radiology department (64%), the endoscopy department (44%) and operating theatres (15%), by surgeons (63%), radiologists (60%) and gastroenterologists (48%). A radiologist was present in 66% of cases. Of 14 hospitals that received referrals, 3 had a protocol, 3 returned patients the same day and 4 returned patients for management in the event of failure. CONCLUSIONS: All responding hospitals in England consider the use of SEMS in colonic obstruction. Nevertheless, there is great variation in stenting practices, and challenges in terms of access and expertise. Centralisation and regional referral networks may help maximise availability and expertise but more work is needed to support this.

MiR-198 affects the proliferation and apoptosis of colorectal cancer through regulation of ADAM28/JAK-STAT signaling pathway.

OBJECTIVE: Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. microRNA-198 (miR-198) was reported to be a tumor suppressive miRNA but its role in CRC is largely unknown. Thus, we aimed to investigate the role of miR-198 and its downstream signaling pathway in CRC. PATIENTS AND METHODS: Quantitative Real-time PCR was conducted to measure miR-198 expression in human CRC cell lines (SW620, SW480 and HT29) and normal colon cell line (FHC). Using MTT, colony formation and flow cytometry assay, we investigated the effects of miR-198 on cell proliferation, colony formation and apoptosis. Luciferase activity reporter assay and Western blot assay were performed to validate the target of miR-198. Using Western blot assay, we detected the protein levels of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway. RESULTS: The results showed that miR-198 expression was significantly reduced in CRC cell lines compared with FHC. Overexpression of miR-198 inhibits CRC cell proliferation and colony formation but promotes apoptosis. Further study revealed ADAM metallopeptidase domain 28 (ADAM28) was a direct target of miR-198, and the overexpression of ADAM28 reversed the effects of miR-198 on cell behaviors. Besides that, miR-198 blocks the JAK/STAT pathway through regulating ADAM28. CONCLUSIONS: These results collectively revealed miR-198 inhibited cell proliferation but promoted apoptosis through targeting ADAM28 and blocking JAK/STAT pathway in CRC cells.

Brain morphological abnormality in schizophrenia is independent of country of origin.

OBJECTIVE: The disorder schizophrenia has a worldwide prevalence of 1% and is generally associated with lateral cerebral ventricular enlargement. Whether there is a relationship between these two findings is unclear but has aetiological relevance. METHOD: Consecutively admitted Chinese patients (n = 19) with first episode of schizophrenia and healthy community volunteers (n = 29) underwent magnetic resonance imaging brain scan. The groups were balanced for age, sex, best social class and handedness. These patients were similar on clinical and socio-demographic indices to those who declined participation (n = 15). Semi-automated volumetric analysis of whole brain volume, cortical grey matter, cerebrospinal fluid, sulci and lateral ventricles was performed. RESULTS: Chinese patients in their first episode of schizophrenia have significant enlargement of lateral ventricles. CONCLUSION: Brain morphological abnormality in schizophrenia is present regardless of the country of origin. The importance of genes in driving normal brain development and stable prevalence suggests that aetiology may favour genes over environment.

Hormonal predisposition to menstrual dysfunction in collegiate dance students.

OBJECTIVE: To evaluate the effect of dance training on menstrual function in teenage dance students and to identify risk factors associated with menstrual dysfunction. METHODS: Dance students from a collegiate school of performing arts were recruited when they were first admitted to the school. Basic epidemiological data and menstrual history were gathered using a structured questionnaire. The subjects' self image appraisal was scored utilizing the Offer Self Image Questionnaire. Anthropometric measurements, body fat percentages and hormonal profiles were measured. The subjects were followed up after 12 months of intensive dance training, and the menstrual pattern, self image scoring and fat composition assays were repeated. RESULTS: A total of 50 students completed the study. The mean age was 18.9 years (s.d. 1.86). While all were eumenorrheic at first assessment, eight were amenorrheic and eight were oligomenorrheic at the second assessment, giving an incidence of menstrual dysfunction of 32%. A general reduction in weight and body fat composition was observed after training. Those with menstrual dysfunction did not differ from those that remained eumenorrheic in their basic anthropometric parameters, nor was the serial change in these parameters in the second assessment different between the two groups. Psychological assessment scores also showed an identical trend. All hormonal values were within the normal range, but the group with menstrual dysfunction showed a significantly higher LH/FSH ratio (p=0.012) and DHEAS levels (p=0.036) at the pre-training assessment while other hormonal parameters did not differ. CONCLUSION: The incidence of menstrual dysfunction in adolescent dance students undergoing intensive training was high. Those with pre-existing hormonal predisposition prior to entering training appeared particularly at risk.

Intelligent database generated occupational questionnaire system.

Obtaining an adequate occupational history requires special expertise to "ask the right questions" that are relevant to a particular patient's specific health conditions and potential exposures. This article describes a way to systematically accomplish this by means of a computer system that can overcome limited availability of necessary clinical occupational health expertise. The Intelligent Questionnaire system is a computer-based system for generating case-specific questionnaires about the influence of work on respiratory disease. Intelligent Questionnaire includes three databases: Questions, Responses, and Calls (clues to identify questions). The Questionnaire also arranges questions in a logical manner and provides a customized data entry screen for each subject. This approach provides primary practitioners with expertise on a case-by-case basis. It also facilitates occupational health surveillance because it allows acquiring detailed case-specific information in a systematic fashion. A computer-based system can facilitate obtaining occupational histories with high specificity and consistency without depending on general availability of a human occupational health clinical expertise.

Fourteen-year follow-up of children with and without speech/language impairments: speech/language stability and outcomes.

This report concerns the speech and language outcomes of young adults (N = 242) who participated in a 14-year, prospective, longitudinal study of a community sample of children with (n = 114) and without (n = 128) speech and/or language impairments. Participants were initially identified at age 5 and subsequently followed at ages 12 and 19. Direct assessments were conducted in multiple domains (communicative, cognitive, academic, behavioral, and psychiatric) at all three time periods. Major findings included (a) high rates of continued communication difficulties in those with a history of impairment; (b) considerable stability in language performance over time; (c) better long-term outcomes for those with initial speech impairments than for those with language impairments; and (d) more favorable prognoses for those with specific language impairments than for those with impairments secondary to sensory, structural, neurological, or cognitive deficits. These general conclusions held when either a liberal or a more stringent criterion for language impairment was employed. Some of these findings are consistent with those from earlier follow-up studies, which used less optimal methods. Thus, the present replication and extension of these findings with a sound methodology enables greater confidence in their use for prognostic, planning, and research purposes.

Exciton splitting in phycoerythrin 545.

Phycoerythrin 545 is a biliprotein having a polypeptide structure of alpha 2 beta 2, and each alpha and beta polypeptide has chromophores. Circular dichroism (CD) and absorption spectroscopy in the visible region together with various biochemical protocols have been used to study these chromophores. The CD spectrum exhibits overlapping positive and negative bands. Exciton splitting between closely-spaced pairs of chromophores produces a CD spectrum that has positive and negative bands of equal rotational strengths, a conservative spectrum. Alternatively, any positive or negative band could arise from a single chromophore. The results of this study demonstrate that exciton splitting is the likely cause of the negative and corresponding positive bands. The CD spectra of the separated alpha and beta polypeptides, under conditions where the polypeptide structure is denatured, have no negative bands. When the polypeptides are allowed to refold individually, the chromophores on the beta polypeptide regain a combination of negative and positive CD bands. The spectrum of the alpha polypeptide shows no evidence of exciton splitting under these refolding conditions. In another approach, urea is added to the protein in low concentrations, which result in changes in the conformation and perhaps association of the protein. A difference CD spectrum of native protein minus protein in 0.8 M urea shows a spectrum characteristic of exciton splitting. Moreover, the remaining CD spectra in 0.8, 1.6, or 2.4 M urea still show the possibility of further exciton splitting, but a slightly different wavelengths from the spectrum that is deleted by 0.8 M urea. This finding may suggest that there are two types of exciton splitting.