Solute effects on edge dislocation pinning in complex alpha-Fe alloys

Reactor pressure vessel steels are well-known to harden and embrittle under neutron irradiation, mainly because of the formation of obstacles to the motion of dislocations, in particular, precipitates and clusters composed of Cu, Ni, Mn, Si and P. In this paper, we employ two complementary atomistic modelling techniques to study the heterogeneous precipitation and segregation of these elements and their effects on the edge dislocations in BCC iron. We use a special and highly computationally efficient Monte Carlo algorithm in a constrained semi-grand canonical ensemble to compute the equilibrium configurations for solute clusters around the dislocation core. Next, we use standard molecular dynamics to predict and analyze the effect of this segregation on the dislocation mobility. Consistently with expectations our results confirm that the required stress for dislocation unpinning from the precipitates formed on top of it is quite large. The identification of the precipitate resistance allows a quantitative treatment of atomistic results, enabling scale transition towards larger scale simulations, such as dislocation dynamics or phase field.Fil: Pascuet, Maria Ines Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Centro Atomico Constituyentes. Departamento de Materiales; ArgentinaFil: Martínez, E.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Monnet, G.. EDF–R&D; FranciaFil: Malerba, L.. SCK•CEN. Structural Materials Expert Group. Nuclear Materials Institute; Bélgic

Effects of cascade-induced dislocation structures on the long-term microstructural evolution in tungsten

In recent years, a number of systematic investigations of high-energy collision cascades in tungsten employing advanced defect analysis tools have shown that interstitial clusters can form complex non-planar dislocation structures. These structures are sessile in nature and may potentially have a strong impact on the long-term evolution of the radiation microstructure. To clarify this aspect, we selected several representative primary damage states of cascades debris and performed annealing simulations using molecular dynamics (MD). We found that immobile complexes of non-planar dislocation structures (CDS) evolve into glissile and planar shaped 1/2 loops with an activation energy of similar to 1.5 eV. The CDS objects were implemented in an object kinetic Monte Carlo (OKMC) model accounting for the event of transformation into 1-D migrating loops, following the MD data. OKMC was then used to investigate the impact of the transformation event (and the associated activation energy) on the evolution of the microstructure.Peer reviewe

Altered Prostasin (CAP1/Prss8) Expression Favors Inflammation and Tissue Remodeling in DSS-induced Colitis.

Inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn's disease are diseases with impaired epithelial barrier function. We aimed to investigate whether mutated prostasin and thus, reduced colonic epithelial sodium channel activity predisposes to develop an experimentally dextran sodium sulfate (DSS)-induced colitis. Wildtype, heterozygous (fr/+), and homozygous (fr/fr) prostasin-mutant rats were treated 7 days with DSS followed by 7 days of recovery and analyzed with respect to histology, clinicopathological parameters, inflammatory marker mRNA transcript expression, and sodium transporter protein expression. In this study, a more detailed analysis on rat fr/fr colons revealed reduced numbers of crypt and goblet cells, and local angiodysplasia, as compared with heterozygous (fr/+) and wildtype littermates. Following 2% DSS treatment for 7 days followed by 7 days recovery, fr/fr animals lost body weight, and reached maximal diarrhea score and highest disease activity after only 3 days, and strongly increased cytokine levels. The histology score significantly increased in all groups, but fr/fr colons further displayed pronounced histological alterations with near absence of goblet cells, rearrangement of the lamina propria, and presence of neutrophils, eosinophils, and macrophages. Additionally, fr/fr colons showed ulcerations and edemas that were absent in fr/+ and wildtype littermates. Following recovery, fr/fr rats reached, although significantly delayed, near-normal diarrhea score and disease activity, but exhibited severe architectural remodeling, despite unchanged sodium transporter protein expression. In summary, our results demonstrate a protective role of colonic prostasin expression against experimental colitis, and thus represent a susceptibility gene in the development of inflammatory bowel disease

Manajemen Risiko Kesehatan Dan Keselamatan Kerja (K3) (Study Kasus Pada Pembangunan Gedung SMA Eben Haezar)

Keselamatan dan Kesehatan Kerja merupakan suatu permasalahan yang banyak menyita perhatian berbagai organisasi saat ini karena mencakup permasalahan segi perikemanusiaan, biaya dan manfaat ekonomi, aspek hukum, pertanggungjawaban serta citra organisasi itu sendiri. Pada penelitian ini akan diteliti mengenai identifikasi risiko K3 , penilaian risiko K3 serta bagaimana tindakan pengendalian terhadap risiko K3 pada kegiatan proyek pembangunan infrastruktur gedung. Metode penilaian menggunakan matriks penilaian risiko yang bersumber dari AS/NZS 4360 : 2004. Sesuai dengan pengolahan data diperoleh nilai risiko yang tinggi, yaitu material terjatuh dari ketinggian dan menimpa pekerja dengan indeks risiko sebesar 20 dan penggolongan risiko pada Very High Risk. Untuk penggolongan risiko pada level High Risk sebanyak 21 variabel yang dapat membahayakan pekerja dan pekerjaan, sedangkan untuk penggolongan pada level Medium Risk didapatkan sebanyak 18 variabel

Routine Screening of Adolescents for Trichomonas vaginalis in a Juvenile Detention Center

Background: Detained and incarcerated adolescents are at increased risk of sexually transmitted infections (STI), but limited information is currently available regarding the prevalence of Trichomonas vaginalis (TV) in detained youth.Methods: A total of 144 detainees (75 males and 69 females) in the Franklin County Juvenile Detention Facility (FCJDF) in Columbus, Ohio, consented to STI screening between May 2016 and June 2017. Participants were screened for TV in addition to Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) using urine nucleic acid amplification tests (NAAT).Results: Among detained youth who consented to testing, TV was identified in 7 of 69 (10.1%) females and 0 of 75 (0%) males (P <0.01). Neisseria gonorrhoeae was identified in 12 of 69 (17.4%) females and 3 of 75 (4.0%) males (P = 0.01), and CT was identified in 16 of 69 (23.2%) female and 7 of 75 (9.3%) male detainees (P = 0.04). Among females, positive TV screen was associated with prior history of STI.Conclusion: Our data support routine screening of female detainees at FCJDF, based on our finding of 10% posi-tivity among females who underwent testing

A novel LAMB2 gene mutation associated with a severe phenotype in a neonate with Pierson syndrome.

BACKGROUND: Pierson syndrome (PS) is a rare autosomal recessive disorder, caused by mutations in the laminin β2 (LAMB2) gene. It is characterized by congenital nephrotic syndrome, microcoria, and neurodevelopmental deficits. Several mutations with genotype-phenotype correlations have been reported, often with great clinical variability. We hereby report a novel homozygous nonsense mutation in the LAMB2 gene, associated with a severe phenotype presentation. CASE DIAGNOSIS: We describe a term male infant born from consanguineous parents. The mother previously lost three children in the neonatal period, secondary to undefined renal disease, had two spontaneous abortions, and gave birth to one healthy daughter. The index case presented at birth with bilateral microcoria, severe hypotonia, respiratory distress, and congenital nephrotic syndrome associated with anuria and severe renal failure requiring peritoneal dialysis. The patients' clinical follow-up was unfavorable, and the newborn died at 7 days of life, after withdrawal of life support. Genetic analysis revealed a homozygous nonsense mutation at position c.2890C>T causing a premature stop codon (p.R964*) in LAMB2 gene. CONCLUSION: We here describe a novel nonsense homozygous mutation in LAMB2 gene causing a severe neonatal presentation of Pierson syndrome. This new mutation expands the genotype-phenotype spectrum of this rare disease and confirms that truncating mutations might be associated with severe clinical features