Understanding defect formation during laser additive manufacturing (LAM) of virgin, stored, and reused powders is crucial for the production of high quality additively manufactured parts. We ...investigate the effects of powder oxidation on the molten pool dynamics and defect formation during LAM. We compare virgin and oxidised Invar 36 powder under overhang and layer-by-layer build conditions using in situ and operando X-ray Imaging. The oxygen content of the oxidised powder was found to be ca. 6 times greater (0.343 wt.%) than the virgin powder (0.057 wt.%). During LAM, the powder oxide is entrained into the molten pool, altering the Marangoni convection from an inward centrifugal to an outward centripetal flow. We hypothesise that the oxide promotes pore nucleation, stabilisation, and growth. We observe that spatter occurs more frequently under overhang conditions compared to layer-by-layer conditions. Droplet spatter can be formed by indirect laser-driven gas expansion and by the laser-induced metal vapour at the melt surface. Under layer-by-layer build conditions, laser re-melting reduces the pore size distribution and number density either by promoting gas release from keyholing or by inducing liquid flow, partially or completely filling pre-existing pores. We also observe that pores residing at the track surface can burst during laser re-melting, resulting in either formation of droplet spatter and an open pore or healing of the pore via Marangoni flow. This study confirms that excessive oxygen in the powder feedstock may cause defect formation in LAM.
Using a laser additive manufacturing process replicator with in situ and operando X-ray imaging (a) permits capturing the formation of (b) porosity and (c) spatter during laser-matter interaction. In addition, we performed post mortem X-ray computed tomography analysis (d) reveal two types of pores inside the melt track: (i) open pores and (ii) closed pores. Display omitted
•Novel molecular data for two genes are provided for 82 species of elasmobranch cestodes.•Phylogenetic analyses result in further dismantling of the speciose order Tetraphyllidea.•Two new cestode ...orders are erected, the Phyllobothriidea and Onchoproteocephalidea.•The Proteocephalidea is subsumed in the Onchoproteocephalidea.•Cestodes of elasmobranchs are found to have played a key role in the evolution of cestodes overall.
Novel molecular data are presented to resolve the long-standing issue of the non-monophyly of the elasmobranch-hosted tapeworm order Tetraphyllidea relative to the other acetabulate eucestode orders. Bayesian inference analyses of various combinations of full ssrDNA, and full or partial lsrDNA (D1–D3), sequence data, which included 134 species representing 97 genera across the 15 eucestode orders, were conducted. New ssrDNA data were generated for 82 species, partial lsrDNA data for 53 species, and full lsrDNA data for 29 species. The monophyly of each of the elasmobranch-hosted orders Cathetocephalidea, Litobothriidea, Lecanicephalidea and Rhinebothriidea was confirmed, as was the non-monophyly of the Tetraphyllidea. Two relatively stable groups of tetraphyllidean taxa emerged and are hereby designated as new orders. The Onchoproteocephalidea n. ord. is established to recognise the integrated nature of one undescribed and 10 described genera of hook-bearing tetraphyllideans, previously placed in the family Onchobothriidae, with the members of the order Proteocephalidea. The Phyllobothriidea n. ord. is established for a subset of 12 non-hooked genera characterised by scoleces bearing four bothridia each with an anterior accessory sucker; most parasitise sharks and have been assigned to the Phyllobothriidae at one time or another. Tentative ordinal placements are suggested for eight additional genera; placements for the remaining tetraphyllidean genera have not yet emerged. We propose that these 17 genera remain in the “Tetraphyllidea”. Among these, particularly labile across analyses were Anthobothrium, Megalonchos, Carpobothrium, Calliobothrium and Caulobothrium. The unique association of Chimaerocestus with holocephalans, rather than with elasmobranchs, appears to represent a host-switching event. Both of the non-elasmobranch hosted clades of acetabulate cestodes (i.e. Proteocephalidea and Cyclophyllidea and their kin) appear to have had their origins with elasmobranch cestodes. Across analyses, the sister group to the clade of “terrestrial” cestode orders was found to be an elasmobranch-hosted genus, as was the sister to the freshwater fish- and tetrapod-hosted Proteocephalidea. Whilst further data are required to resolve outstanding nomenclatural and phylogenetic issues, the present analyses contribute significantly to an understanding of the evolutionary radiation of the entire Cestoda. Clearly, elasmobranch tapeworms comprise the backbone of cestode phylogeny.
To identify health and psychosocial problems associated with bullying victimization and conduct a meta-analysis summarizing the causal evidence.
A systematic review was conducted using PubMed, ...EMBASE, ERIC and PsycINFO electronic databases up to 28 February 2015. The study included published longitudinal and cross-sectional articles that examined health and psychosocial consequences of bullying victimization. All meta-analyses were based on quality-effects models. Evidence for causality was assessed using Bradford Hill criteria and the grading system developed by the World Cancer Research Fund.
Out of 317 articles assessed for eligibility, 165 satisfied the predetermined inclusion criteria for meta-analysis. Statistically significant associations were observed between bullying victimization and a wide range of adverse health and psychosocial problems. The evidence was strongest for causal associations between bullying victimization and mental health problems such as depression, anxiety, poor general health and suicidal ideation and behaviours. Probable causal associations existed between bullying victimization and tobacco and illicit drug use.
Strong evidence exists for a causal relationship between bullying victimization, mental health problems and substance use. Evidence also exists for associations between bullying victimization and other adverse health and psychosocial problems, however, there is insufficient evidence to conclude causality. The strong evidence that bullying victimization is causative of mental illness highlights the need for schools to implement effective interventions to address bullying behaviours.
The physics of stratum corneum lipid membranes Das, Chinmay; Olmsted, Peter D.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
07/2016, Letnik:
374, Številka:
2072
Journal Article
Recenzirano
Odprti dostop
The stratum corneum (SC), the outermost layer of skin, comprises rigid corneocytes (keratin-filled dead cells) in a specialized lipid matrix. The continuous lipid matrix provides the main barrier ...against uncontrolled water loss and invasion of external pathogens. Unlike all other biological lipid membranes (such as intracellular organelles and plasma membranes), molecules in the SC lipid matrix show small hydrophilic groups and large variability in the length of the alkyl tails and in the numbers and positions of groups that are capable of forming hydrogen bonds. Molecular simulations provide a route for systematically probing the effects of each of these differences separately. In this article, we present the results from atomistic molecular dynamics of selected lipid bilayers and multi-layers to probe the effect of these polydispersities. We address the nature of the tail packing in the gel-like phase, the hydrogen bond network among head groups, the bending moduli expected for leaflets comprising SC lipids and the conformation of very long ceramide lipids in multi-bilayer lipid assemblies.
This article is part of the themed issue ‘Soft interfacial materials: from fundamentals to formulation’.
Weather and climate models must continue to increase in both resolution and complexity in order that forecasts become more accurate and reliable. Moving to lower numerical precision may be an ...essential tool for coping with the demand for ever increasing model complexity in addition to increasing computing resources. However, there have been some concerns in the weather and climate modelling community over the suitability of lower precision for climate models, particularly for representing processes that change very slowly over long time-scales. These processes are difficult to represent using low precision due to time increments being systematically rounded to zero. Idealised simulations are used to demonstrate that a model of deep soil heat diffusion that fails when run in single precision can be modified to work correctly using low precision, by splitting up the model into a small higher precision part and a low precision part. This strategy retains the computational benefits of reduced precision whilst preserving accuracy. This same technique is also applied to a full complexity land surface model, resulting in rounding errors that are significantly smaller than initial condition and parameter uncertainties. Although lower precision will present some problems for the weather and climate modelling community, many of the problems can likely be overcome using a straightforward and physically motivated application of reduced precision.
Plus-stranded RNA viruses replicate in infected cells by assembling viral replicase complexes consisting of viral- and host-coded proteins. Previous genome-wide screens with Tomato bushy stunt ...tombusvirus (TBSV) in a yeast model host revealed the involvement of seven ESCRT (endosomal sorting complexes required for transport) proteins in viral replication. In this paper, we show that the expression of dominant negative Vps23p, Vps24p, Snf7p, and Vps4p ESCRT factors inhibited virus replication in the plant host, suggesting that tombusviruses co-opt selected ESCRT proteins for the assembly of the viral replicase complex. We also show that TBSV p33 replication protein interacts with Vps23p ESCRT-I and Bro1p accessory ESCRT factors. The interaction with p33 leads to the recruitment of Vps23p to the peroxisomes, the sites of TBSV replication. The viral replicase showed reduced activity and the minus-stranded viral RNA in the replicase became more accessible to ribonuclease when derived from vps23Delta or vps24Delta yeast, suggesting that the protection of the viral RNA is compromised within the replicase complex assembled in the absence of ESCRT proteins. The recruitment of ESCRT proteins is needed for the precise assembly of the replicase complex, which might help the virus evade recognition by the host defense surveillance system and/or prevent viral RNA destruction by the gene silencing machinery.
Motivated by recent high-profile cases of salespeople behaving ‘badly’ (i.e., unethically, aggressively, or misleading toward customers), we investigate traditional behavioral controls to examine the ...specific relationship between performance measurement choices and selling behavior with a survey of 207 business-to-business salespeople. Borrowing from attention-based theory and the theory of planned behavior, our findings suggest that sales management can encourage more pro-customer behavior by using a more diverse performance measurement schema to influence the underlying drivers of customer-oriented selling behavior, including salesperson attitudes and subjective norms. This is particularly important in transactional selling environments where the use of diverse measures has the strongest effect on pro-customer attitudes and customer-oriented selling behavior.
•Increased performance measurement diversity is linked to customer-oriented selling behavior.•Salesperson attitudes are chiefly responsible for higher levels of customer-oriented selling behavior.•The influence of attitudes on customer-oriented selling is most acute in less complex, transactional selling situations.
Esophageal strictures are a problem commonly encountered in gastroenterological practice and can be caused by malignant or benign lesions. Dysphagia is the symptom experienced by all patients, ...regardless of whether their strictures are caused by malignant or benign lesions. The methods most frequently used for palliation of malignant esophageal strictures are stent placement (particularly in patients with an expected survival of 3 months or less) and brachytherapy (in patients with a life expectancy of more than 3 months). Brachytherapy has been shown to be beneficial in patients with an expected survival of longer than 3 months with regard to (prolonged) dysphagia improvement, complications and quality of life. The mainstay of benign esophageal stricture treatment is dilation. Although dilation usually results in symptomatic relief, recurrent strictures do occur. In order to predict which types of strictures are most likely to recur, it is important to differentiate between esophageal strictures that are simple (i.e. focal, straight strictures with a diameter that allows endoscope passage) and those that are more complex (i.e. long (>2 cm), tortuous strictures with a narrow diameter). These complex strictures are considered refractory when they cannot be dilated to an adequate diameter. Novel treatment modalities for refractory strictures include temporary stent placement and incisional therapy.
We evaluated the efficacy and safety of upadacitinib, an oral selective inhibitor of Janus kinase 1, as induction therapy for ulcerative colitis (UC).
We performed a multicenter, double-blind, phase ...2b study of 250 adults with moderately to severely active UC and an inadequate response, loss of response, or intolerance to corticosteroids, immunosuppressive agents, and/or biologic therapies. Patients were randomly assigned to groups that received placebo or induction therapy with upadacitinib (7.5 mg, 15 mg, 30 mg, or 45 mg, extended release), once daily for 8 weeks. The primary endpoint was the proportion of participants who achieve clinical remission according to the adapted Mayo score at week 8. No multiplicity adjustments were applied.
At week 8, 8.5%, 14.3%, 13.5%, and 19.6% of patients receiving 7.5 mg, 15 mg, 30 mg, or 45 mg upadacitinib, respectively, achieved clinical remission compared with none of the patients receiving placebo (P = .052, P = .013, P = .011, and P = .002 compared with placebo, respectively). Endoscopic improvement at week 8, defined as endoscopic subscore of ≤ 1, was achieved in 14.9%, 30.6%, 26.9%, and 35.7% of patients receiving upadacitinib 7.5 mg, 15 mg, 30 mg, or 45 mg, respectively, compared with 2.2% receiving placebo (P = .033, P < .001, P < .001, and P < .001 compared with placebo, respectively). One event of herpes zoster and 1 participant with pulmonary embolism and deep venous thrombosis (diagnosed 26 days after treatment discontinuation) were reported in the group that received upadacitinib 45 mg once daily. Increases in serum lipid levels and creatine phosphokinase with upadacitinib were observed.
In a phase 2b trial, 8 weeks of treatment with upadacitinib was more effective than placebo for inducing remission in patients with moderately to severely active UC. (ClinicalTrials.gov, Number: NCT02819635)
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