The Formation of Fragments at Corotation in Isothermal Protoplanetary Disks

Numerical hydrodynamics simulations have established that disks which are evolved under the condition of local isothermality will fragment into small dense clumps due to gravitational instabilities when the Toomre stability parameter $Q$ is sufficiently low. Because fragmentation through disk instability has been suggested as a gas giant planet formation mechanism, it is important to understand the physics underlying this process as thoroughly as possible. In this paper, we offer analytic arguments for why, at low $Q$, fragments are most likely to form first at the corotation radii of growing spiral modes, and we support these arguments with results from 3D hydrodynamics simulations.Comment: 21 pages, 1 figur

Ancestral diversity improves discovery and fine-mapping of genetic loci for anthropometric traits — The Hispanic/Latino Anthropometry Consortium

Hispanic/Latinos have been underrepresented in genome-wide association studies (GWAS) for anthropometric traits despite their notable anthropometric variability, ancestry proportions, and high burden of growth stunting and overweight/obesity. To address this knowledge gap, we analyzed densely imputed genetic data in a sample of Hispanic/Latino adults to identify and fine-map genetic variants associated with body mass index (BMI), height, and BMI-adjusted waist-to-hip ratio (WHRadjBMI). We conducted a GWAS of 18 studies/consortia as part of the Hispanic/Latino Anthropometry (HISLA) Consortium (stage 1, n = 59,771) and generalized our findings in 9 additional studies (stage 2, n = 10,538). We conducted a trans-ancestral GWAS with summary statistics from HISLA stage 1 and existing consortia of European and African ancestries. In our HISLA stage 1 + 2 analyses, we discovered one BMI locus, as well as two BMI signals and another height signal each within established anthropometric loci. In our trans-ancestral meta-analysis, we discovered three BMI loci, one height locus, and one WHRadjBMI locus. We also identified 3 secondary signals for BMI, 28 for height, and 2 for WHRadjBMI in established loci. We show that 336 known BMI, 1,177 known height, and 143 known WHRadjBMI (combined) SNPs demonstrated suggestive transferability (nominal significance and effect estimate directional consistency) in Hispanic/Latino adults. Of these, 36 BMI, 124 height, and 11 WHRadjBMI SNPs were significant after trait-specific Bonferroni correction. Trans-ancestral meta-analysis of the three ancestries showed a small-to-moderate impact of uncorrected population stratification on the resulting effect size estimates. Our findings demonstrate that future studies may also benefit from leveraging diverse ancestries and differences in linkage disequilibrium patterns to discover novel loci and additional signals with less residual population stratification

Gastrointestinal stromal tumor of the stomach. Case report

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the alimentary tract. Nowadays GISTs represents 0.1–3% of all gastrointestinal malignancies, making it a diagnostic challenge. Lesions are frequently located in stomach and proximal small intestine but rarely elsewhere in the abdomen. They are believed to result from mutations of proto-oncogenes c-Kit or platelet-derived growth factor receptor alpha polypeptide, this increase tyrosine kinase receptor activity, leading to uncontrolled proliferation of stem cells that differentiate into cells of Cajal. They can occur at any age but predominantly in middle-aged people and in elderly. We report the case of a 28-year-old male presented to our hospital with upper gastrointestinal bleeding, findings in diagnostic image studies suggested a gastric GIST without evidence of metastatic disease; therefore totally tumor excision was performed. Cytologic and inmunohistochemistry analysis confirm diagnosis of GISTs. Resumen: Los tumores del estroma gastrointestinal (GISTs) son neoplasias raras de origen mesenquimal en el tracto alimentario. Típicamente se localizan en estómago e intestino delgado proximal, con pocos casos en otros sitios en abdomen. Se sabe que los GIST pueden ser el resultado de mutaciones de proto-oncogenes c-Kit o del receptor alfa polipeptídico del factor de crecimiento derivado de plaquetas, esto aumenta la actividad de receptor tirosincinasa y lleva a una proliferación descontrolada de células madre que se derivarían a Células de Cajal. Ocurren a cualquier edad pero son frecuentes en la mediana edad y en la vejez. Reportamos el caso de un paciente masculino de 28 años de edad quien inicia con hemorragia de tubo digestivo alto, los hallazgos en los estudios de imagen sugirieron un GIST gástrico sin evidencia de enfermedad metastásica, se realizó excisión total del tumor. Análisis citológico e inmunohistoquímico positivos para GIST. Keywords: Gastrointestinal stromal tumors, GIST, CD117 antigen, Proto-oncogene c-Kit, Palabras clave: Tumores del estroma gastrointestinal, GIST, Antígeno CD117, Proto-oncogén c-Ki

Chemical modification of alginate with cysteine and its application for the removal of Pb(II) from aqueous solutions

13 pags., 22 figs., 8 tabs.IIt has been synthesized, characterized and tested a new biomaterial AlgS (sodium alginate functionalized with cysteine) to remove Pb(II) in aqueous media. The maximum Pb(II)-sorption capacity of AlgS (Qmax = 770 mg·g−1) is between almost two and nine times higher than other alginate-materials reported in the literature. Techniques, such as TGA/DSC, SEM/EDS, BET, FTIR, UV–Vis, XRD and 13C solid state-NMR have been used to study the chemical-modification of alginate at oxidation and aminofication stages. The formation of the imine intermediate (C=N), after 24 h of reaction was identified by a UV band at 348 nm. Typical IR-bands of AlgS were identified at 2970, 955, 949 and 1253 cm−1 which are associated to CH, SPb, SH and CN stretching vibrations, respectively. 13C solid state-NMR spectra of AlgS, show peaks at 33–38 ppm and 55–60 ppm associate to δ (HS-CH2-) of cysteine and δ (CN) respectively. The ΔH° and ΔG° negative values for Pb(II) sorption indicate that it is an exothermic process and occur spontaneously. Finally, it was found that the Pb(II) sorption on AlgS is significantly affected by the presence of cationic (Na+, Mg2+ and Al3+) and anionic (Cl−, NO3−) co-ions.The authors gratefully acknowledge to the National Innovation Program for Competitiveness and Productivity - Innóvate Peru, Contract187-IB-2013 for the assigned RNR funds.Also, the author Ronny G. Huamani-Palomino is thankful to Dr.Demetrio Miranda and Dr. Braulio R. Molina for the opportunity to doa research in the Chemistry Institute of UNAM-Mexic

Chemical modification of sodium alginate with thiosemicarbazide for the removal of Pb(II) and Cd(II) from aqueous solutions

A new material (Alg–TSC), based on alginate (Alg) chemically modified with thiosemicarbazide (TSC), has been synthesized and tested as an effective biomaterial to remove Pb(II) and Cd(II) ions in aqueous solutions. The synthesis was carried out by controlling the following steps, i/partial oxidation process of alginate in NaIO to obtain AlgOx, ii/reacting of AlgOx, at 40–45 °C, with TSC in NaBH. Alg–TSC has been characterized by Field Emission Scanning Electron Microscopy (FESEM/EDS), Fourier Transform Infrared Spectroscopy (ATR-IR), solid state C NMR spectroscopy and Point of Zero Charge (pH) measuremenmts. In order to enhance the sorption process, the effect of contact time, sorbent dosage, initial concentration and reusability of the novel sorbent were investigated becoming the Alg–TSC a promising material capable of removing high concentrations of heavy metal ions such as Pb(II) (up to 950 mg/g at pH 3) and Cd(II) (up to 300 mg/g at pH 7) in aqueous solutions.Peer Reviewe