Sulfonic acid coating of refractory sand for three-dimensional printing applications

Abstract: Rapid sand casting processes by additive manufacturing are predominantly based on furfuryl alcohol resin bonded sand catalysed with sulfonic acid. The prior coating of the refractory sand with sulfonic acid is a crucial process to ensure the suitability of the sand for threedimensional printing applications. The present paper investigated the sulfonic acid coating process of a local silica sand, which was found to have potential for three-dimensional printing applications in previous studies. Experimental conditions included sulfonic acid catalyst addition and mixing time. Coated sand was assessed for flowability and mechanical properties of test specimens produced by three-dimensional printing using a Voxeljet VX 1000. The optimum catalyst addition ranged between 0.3 and 0.6% yielding to transverse strength in the order of 110 to 165 KN/m2 and tensile strength ranging from 710 to 770 KN/m2

Evaluation of the phenolic and flavonoid contents and radical scavenging activity of three southern African medicinal plants

Warburgia salutaris (Bertol. F.) Chiovs, Rhoicissus tridentata (L.f.) Wild & Drum and Terminalia sericea (Burch. ex DC.), are widely used medicinal plants in southern Africa. The aim of the study was to determine the phenolic and flavonoid content and evaluate the antioxidant activity of the three medicinal plants. Total phenolic and flavonoid contents were determined spectrophotometrically as gallic acid and rutin equivalents, respectively. Individual phenolic acids were identified by means of gas chromatography-mass spectrometry. Antioxidant activities of the crude extracts were assessed using the TEAC assay. The highest phenolic content was detected in the crude methanol extract of the bark of W. salutaris and the highest flavonoid content was found in the crude methanol extract of the leaves of this plant. In all the studied plants the alkaline hydrolysable fraction yielded a greater variety of phenolic acids compared to the soluble/free phenolic acid fractions. The three medicinal plants investigated were found to be strong radical scavengers supporting the traditional use of these medicinal plants.The Gauteng Department of Health and the National Research Foundation in South Africa.http://www.academicjournals.org/AJPPam201

An Empirical Study of Bots in Software Development -- Characteristics and Challenges from a Practitioner's Perspective

Software engineering bots - automated tools that handle tedious tasks - are increasingly used by industrial and open source projects to improve developer productivity. Current research in this area is held back by a lack of consensus of what software engineering bots (DevBots) actually are, what characteristics distinguish them from other tools, and what benefits and challenges are associated with DevBot usage. In this paper we report on a mixed-method empirical study of DevBot usage in industrial practice. We report on findings from interviewing 21 and surveying a total of 111 developers. We identify three different personas among DevBot users (focusing on autonomy, chat interfaces, and "smartness"), each with different definitions of what a DevBot is, why developers use them, and what they struggle with. We conclude that future DevBot research should situate their work within our framework, to clearly identify what type of bot the work targets, and what advantages practitioners can expect. Further, we find that there currently is a lack of general purpose "smart" bots that go beyond simple automation tools or chat interfaces. This is problematic, as we have seen that such bots, if available, can have a transformative effect on the projects that use them.Comment: To be published at the ACM Joint European Software Engineering Conference and Symposium on the Foundations of Software Engineering (ESEC/FSE

Long-term safety and efficacy of alirocumab in South African patients with heterozygous familial hypercholesterolaemia : the ODYSSEY open-label extension study

BACKGROUND : Alirocumab reduces low-density lipoprotein cholesterol (LDL-C) levels by up to 61%. The ODYSSEY Open-Label Extension study investigated the effect of alirocumab in patients with heterozygous familial hypercholesterolaemia (HeFH) over 144 weeks. METHODS : Eligible patients with HeFH had completed an earlier double-blind, randomised, placebo-controlled parent study. Patients were initiated on 75 mg alirocumab Q2W subcutaneous (SC) unless baseline LDL-C was > 8.9 mmol/l, in which case they received 150 mg alirocumab Q2W. Dose titration to 150 mg Q2W was at the investigator’s discretion. RESULTS : The study enrolled 167 patients and the parent study mean (± SD) baseline LDL-C level was 3.65 ± 1.9 mmol/l. Mean LDL-C level was reduced by 48.7% at week 144; mean on-treatment LDL-C was 2.30 ± 1.24 mmol/l. Eight patients reported injection-site reactions, with one treatment discontinuation. Treatment emergent anti-drug antibodies were identified in five patients but these did not affect the efficacy. CONCLUSION : Alirocumab effectively and safely reduced LDL-C in these patients.http://www.cvja.co.zahj2020Physiolog

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

Evidence for a vector charmonium-like state in e+e−→Ds+Ds2∗(2573)−+c.c.e^+e^- \to D^+_sD^*_{s2}(2573)^-+c.c.

We report the measurement of $e^+e^- \to D^+_sD^*_{s2}(2573)^-+c.c.$ via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb$^{-1}$ collected with the Belle detector at the $\Upsilon(4S)$ and nearby. We find evidence for an enhancement with a 3.4$\sigma$ significance in the invariant mass of $D^+_sD^*_{s2}(2573)^- +c.c.$ The measured mass and width are $(4619.8^{+8.9}_{-8.0}({\rm stat.})\pm2.3({\rm syst.}))~{\rm MeV}/c^{2}$ and $(47.0^{+31.3}_{-14.8}({\rm stat.})\pm4.6({\rm syst.}))~{\rm MeV}$, respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmonium-like state at 4626 MeV/$c^2$ recently reported by Belle in $e^+e^-\to D^+_sD_{s1}(2536)^-+c.c.$ The product of the $e^+e^-\to D^+_sD^*_{s2}(2573)^-+c.c.$ cross section and the branching fraction of $D^*_{s2}(2573)^-\to{\bar D}^0K^-$ is measured from $D^+_sD^*_{s2}(2573)^-$ threshold to 5.6 GeV.Comment: 9 pages, 4 figure

Measurement of the Branching Fraction of the Decay B+→π+π−ℓ+νℓ\boldsymbol{B^{+}\to\pi^{+}\pi^{-}\ell^{+}\nu_\ell} in Fully Reconstructed Events at Belle

We present an analysis of the exclusive $B^{+}\to\pi^{+}\pi^{-}\ell^{+}\nu_{\ell}$ decay, where $\ell$ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The analysis uses the full $\Upsilon(4S)$ data sample collected by the Belle detector, corresponding to 711 fb$^{-1}$ of integrated luminosity. We select the events by fully reconstructing one $B$ meson in hadronic decay modes, subsequently determining the properties of the other $B$ meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of ${{\cal B}(B^{+}\to \pi^{+}\pi^{-}\ell^{+}\nu_{\ell})= [22.7 ^{+1.9}_{-1.6} (\mathrm{stat}) \pm 3.5(\mathrm{syst}) ]\times 10^{-5}}$, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.Comment: 23 pages, 19 figure

Diagnostic accuracy of non-specialist versus specialist health workers in diagnosing hearing loss and ear disease in Malawi.

OBJECTIVE: To determine whether a non-specialist health worker can accurately undertake audiometry and otoscopy, the essential clinical examinations in a survey of hearing loss, instead of a highly skilled specialist (i.e. ENT or audiologist). METHODS: A clinic-based diagnostic accuracy study was conducted in Malawi. Consecutively sampled participants ≥ 18 years had their hearing tested using a validated tablet-based audiometer (hearTest) by an audiologist (gold standard), an audiology officer, a nurse and a community health worker (CHW). Otoscopy for diagnosis of ear pathologies was conducted by an ENT specialist (gold standard), an ENT clinical officer, a CHW, an ENT nurse and a general nurse. Sensitivity, specificity and kappa (κ) were calculated. 80% sensitivity, 70% specificity and kappa of 0.6 were considered adequate. RESULTS: Six hundred and seventeen participants were included. High sensitivity (>90%) and specificity (>85%) in detecting bilateral hearing loss was obtained by all non-specialists. For otoscopy, sensitivity and specificity were >80% for all non-specialists in diagnosing any pathology except for the ENT nurse. Agreement in diagnoses for the ENT clinical officer was good (κ = 0.7) in both ears. For other assessors, moderate agreement was found (κ = 0.5). CONCLUSION: A non-specialist can be trained to accurately assess hearing using mobile-based audiometry. However, accurate diagnosis of ear conditions requires at least an ENT clinical officer (or equivalent). Conducting surveys of hearing loss with non-specialists could lower costs and increase data collection, particularly in low- and middle-income countries, where ENT specialists are scarce

Field-testing of a rapid survey method to assess the prevalence and causes of hearing loss in Gao'an, Jiangxi province, China.

BACKGROUND: The Rapid Assessment of Hearing Loss (RAHL) survey protocol aims to measure the prevalence and causes of hearing loss in a low cost and rapid manner, to inform planning of ear and hearing services. This paper reports on the first field-test of the RAHL in Gao'an County, Jiangxi Province, China. This study aimed to 1) To report on the feasibility of RAHL; 2) report on the estimated prevalence and causes of hearing loss in Gao'an. METHODS: A cross-sectional population-based survey was conducted in September-October 2018. Forty-seven clusters in Gao'an County were selected using probability-proportionate-to-size sampling. Within clusters, compact segment sampling was conducted to select 30 people aged 50+. A questionnaire was completed covering sociodemographics, hearing health, and risk factors. Automated pure-tone audiometry was completed for all participants, using smartphone-based audiometry (hearTest), at 0.5, 1, 2, 4 kHz (kHz). All participants had their ears examined by an Ear Nose and Throat (ENT) doctor, using otoscopy, and probable causes of hearing loss assigned. Prevalence estimates were age and sex standardised to the Jiangxi population. Feasibility of a cluster size of 30 was examined by assessing the response rate, and the proportion of clusters completed in 1 day. RESULTS: 1344 of 1421 eligible participants completed the survey (94.6%). 100% of clusters were completed in 1 day. The survey was completed in 4.5 weeks. The prevalence of moderate or greater hearing loss (pure-tone average of 0.5, 1, 2, 4 kHz of > = 41dBHL in the better ear) was 16.3% (95% CI = 14.3, 18.5) and for any level of hearing loss (pure-tone average of > = 26dBHL in the better ear) the prevalence was 53.2% (95% CI = 49.2, 57.1). The majority of hearing loss was due to acquired sensorineural causes (91.7% left; 92.1% right). Overall 54.0% of the population aged 50+ (108,000 people) are in need of diagnostic audiology services, 3.4% were in need of wax removal (7000 people), and 4.8% were in need of surgical services (9500 people). Hearing aid coverage was 0.4%. CONCLUSION: The RAHL survey protocol is feasible, demonstrated through the number of people examined per day, and the high response rate. The survey was completed in a much shorter period than previous all-age surveys in China. Some remaining challenges included assignment of causes of probable sensorineural loss. The data obtained from this survey can be used to scale-up hearing services in Gao'an