Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control

A method in which a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, as well as certain transition metals including nickel, iron, and manganese is described. The tube is then evacuated and heated to a temperature within a range of 800 C to 1400 C. A stream of gas comprising a reactant, such as silicon tetrafluoride, is continuously delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. The reactant which included carbon monoxide gas and impurities such as iron and nickel react to form volatile carbonyls

RADIX-10 PARALLEL DECIMAL MULTIPLIER

This paper introduces novel architecture for Radix-10 decimal multiplier. The new generation of highperformance decimal floating-point units (DFUs) is demanding efficient implementations of parallel decimal multiplier. The parallel generation of partial products is performed using signed-digit radix-10 recoding of the multiplier and a simplified set of multiplicand multiples. The reduction of partial products is implemented in a tree structure based on a new algorithm decimal multioperand carry-save addition that uses a unconventional decimal-coded number systems. We further detail these techniques and it significantly improves the area and latency of the previous design, which include: optimized digit recoders, decimal carry-save adders (CSA’s) combining different decimal-coded operands, and carry free adders implemented by special designed bit counters

Semiconductor Grade, Solar Silicon Purification Project

A low cost by-product, SiF4, is reacted with mg silicon to form SiF2 gas which is polymerized. The (SiF2)x polymer is heated forming volatile SixFy homologues which disproportionate on a silicon particle bed forming silicon and SiF4. The silicon analysis procedure relied heavily on mass spectroscopic and emission spectroscopic analysis. These analyses demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). However, electrical analysis via crystal growth reveal that the product contains compensated phosphorus and boron

Semiconductor grade, solar silicon purification project

Experimental apparatus and procedures used in the development of a 3-step SiF2(x) polymer transport purification process are described. Both S.S.M.S. and E.S. analysis demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). Recent electrical analysis via crystal growth reveals that the product contains compensated phosphorus and boron. The low projected product cost and short energy payback time suggest that the economics of this process will result in a cost less than the goal of $10/Kg(1975 dollars). The process appears to be readily scalable to a major silicon purification facility

Cleaving-temperature dependence of layered-oxide surfaces

The surfaces generated by cleaving non-polar, two-dimensional oxides are often considered to be perfect or ideal. However, single particle spectroscopies on Sr2RuO4, an archetypal non-polar two dimensional oxide, show significant cleavage temperature dependence. We demonstrate that this is not a consequence of the intrinsic characteristics of the surface: lattice parameters and symmetries, step heights, atom positions, or density of states. Instead, we find a marked increase in the density of defects at the mesoscopic scale with increased cleave temperature. The potential generality of these defects to oxide surfaces may have broad consequences to interfacial control and the interpretation of surface sensitive measurements

Performance metrics for the evaluation of hyperspectral chemical identification systems

Remote sensing of chemical vapor plumes is a difficult but important task for many military and civilian applications. Hyperspectral sensors operating in the long-wave infrared regime have well-demonstrated detection capabilities. However, the identification of a plume’s chemical constituents, based on a chemical library, is a multiple hypothesis testing problem which standard detection metrics do not fully describe. We propose using an additional performance metric for identification based on the so-called Dice index. Our approach partitions and weights a confusion matrix to develop both the standard detection metrics and identification metric. Using the proposed metrics, we demonstrate that the intuitive system design of a detector bank followed by an identifier is indeed justified when incorporating performance information beyond the standard detection metrics.United States. Defense Threat Reduction Agency (Air Force contract FA8721-05-C-0002

Dissemination and stakeholder engagement practices among dissemination & implementation scientists: Results from an online survey

IntroductionThere has been an increasing focus on disseminating research findings, but less about practices specific to disseminating and engaging non-researchers. The present project sought to describe dissemination practices and engagement of stakeholders among dissemination & implementation (D&I) scientists.MethodsMethods to disseminate to and engage non-research stakeholders were assessed using an online survey sent to a broad, diverse sample of D&I scientists.ResultsSurveys were received from 210 participants. The majority of respondents were from university or research settings in the United States. (69%) or Canada (13%), representing a mix of clinical (28%) and community settings (34%). 26% had received formal training in D&I. Respondents indicated routinely engaging in a variety of dissemination-related activities, with academic journal publications (88%), conference presentations (86%), and reports to funders (74%) being the most frequent. Journal publication was identified as the most impactful on respondents' careers (94%), but face-to-face meetings with stakeholders were rated as most impactful on practice or policy (40%). Stakeholder involvement in research was common, with clinical and community-based researchers engaging stakeholder groups in broadly similar ways, but with critical differences noted between researchers with greater seniority, those with more D&I training, those based in the United States vs. Canada, and those in community vs. clinical research settings.ConclusionsThere have been increases in stakeholder engagement, but few other practices since the 2012 survey, and some differences across subgroups. Methods to engage different stakeholders deserve more in-depth investigation. D&I researchers report substantial misalignment of incentives and behaviors related to dissemination to non-research audiences

A systematic review of high-intensity interval training as an exercise intervention for intermittent claudication

BackgroundIntermittent claudication (IC) is the most common symptom of peripheral arterial disease, which significantly affects walking ability, functional capacity and quality of life. Supervised exercise programs (SEP) are recommended as first-line treatment, but recruitment and adherence rates are poor. The time required to complete a SEP is the most common barrier to participation cited by patients who decline. High-intensity interval training (HIIT) is more time efficient than current SEPs and therefore has the potential to overcome this barrier. We conducted a systematic review to appraise the evidence for HIIT programs for IC.MethodsMEDLINE, Embase, and CENTRAL databases were searched for terms related to HIIT and IC. Randomized and nonrandomized trials that investigated HIIT for the treatment of IC were included, with no exclusions based on exercise modality, protocol, or use of a comparator arm. Outcome measures were walking distances, peak oxygen uptake, recruitment and adherence rates, and quality of life. The risk of bias was assessed using the Cochrane tool and study quality using a modified Physiotherapy Evidence Database scale.ResultsNine articles reporting eight studies were included in the review. HIIT seems to improve walking distances and oxygen uptake in relation to controls, with improvements attainable in just 6 weeks. When HIIT was compared with low-intensity exercise, it seemed that longer low-intensity programs were required to obtain similar benefits to those from short-term HIIT.ConclusionsInitial evidence suggests that HIIT may provide benefits for patients with IC. Initially, pilot studies of low-volume, short-term HIIT vs usual SEPs are required. This strategy will allow for larger randomized, controlled trials to be appropriately designed and adequately powered to further explore the potential benefits of HIIT in IC

Home-based exercise programmes for individuals with intermittent claudication: A protocol for an updated systematic review and meta-analysis

Background: The aim of this updated review is to consider the evidence base for the effectiveness of home-based exercise programmes (HEP) as a treatment option for improving walking distance in patients with IC.Methods: The Medline, EMBASE, CINAHL, PEDro and Cochrane CENTRAL databases will be searched for terms including “intermittent claudication”, “peripheral arterial disease”, “home-based exercise” and “home-based walking”. No date restrictions will be used but only articles in the English language will be included. Both randomised and non-randomised trials of HEP’s versus a comparator arm will be included, and a meta-analysis using only the randomised controlled trials will be attempted if the assumptions of heterogeneity are met. Data extraction will include study details, sample description, intervention description, length of follow up and outcomes measures. The primary outcome measure is objectively measured maximal walking distance or time, with secondary outcome measures including pain-free walking distance or time, changes in physical activity and quality of life. We will also provide a narrative description of the effective components of a home-based exercise intervention which can aid future recommendations. Conclusion: Overall, this proposed review and meta-analysis aims to provide a comprehensive and complete overview of the evidence base for HEP’s, which can aid clinicians in the management of their patients.PROSPERO registration number: CRD4201809124