Chemical studies of the passivation of GaAs surface recombination using sulfides and thiols

Steady-state photoluminescence, time-resolved photoluminescence, and x-ray photoelectron spectroscopy have been used to study the electrical and chemical properties of GaAs surfaces exposed to inorganic and organic sulfur donors. Despite a wide variation in S2–(aq) concentration, variation of the pH of aqueous HS–solutions had a small effect on the steady-state n-type GaAs photoluminescence intensity, with surfaces exposed to pH=8, 0.1-M HS–(aq) solutions displaying comparable luminescence intensity relative to those treated with pH=14, 1.0-M Na2S·9H2O(aq). Organic thiols (R-SH, where R=–CH2CH2SH or –C6H4Cl) dissolved in nonaqueous solvents were found to effect increases in steady-state luminescence yields and in time-resolved luminescence decay lifetimes of (100)-oriented GaAs. X-ray photoelectron spectroscopy showed that exposure of GaAs surfaces to these organic systems yielded thiols bound to the GaAs surface, but such exposure did not remove excess elemental As and did not form a detectable As2S3 overlayer on the GaAs. These results imply that complete removal of As0 or formation of monolayers of As2S3 is not necessary to effect a reduction in the recombination rate at etched GaAs surfaces. Other compounds that do not contain sulfur but that are strong Lewis bases, such as methoxide ion, also improved the GaAs steady-state photoluminescence intensity. These results demonstrate that a general class of electron-donating reagents can be used to reduce nonradiative recombination at GaAs surfaces, and also imply that prior models focusing on the formation of monolayer coverages of As2S3 and Ga2S3 are not adequate to describe the passivating behavior of this class of reagents. The time-resolved, high level injection experiments clearly demonstrate that a shift in the equilibrium surface Fermi-level energy is not sufficient to explain the luminescence intensity changes, and confirm that HS– and thiol-based reagents induce substantial reductions in the surface recombination velocity through a change in the GaAs surface state recombination rate

The amino acid sequence of Erythrina corallodendron lectin and its homology with other legume lectins

AbstractThe primary sequence of Erythrina corallodendron lectin was deduced from analysis of the peptides derived from the lectin by digestion with trypsin, chymotrypsin, Staphylococcus aureus V8 protease, elastase and lysylendopeptidase-C, and of fragments generated by cleavage of the lectin with dilute formic acid in 6 M guanidine hydrochloride. Purification of the individual peptides was achieved by gel nitration, followed by reverse phase HPLC. The glycosylation site (Asn17-Leu18-Thr19) was deduced from analysis of the glycopeptide isolated from a pronase digest of the lectin before and after deglycosylation of the glycopeptide with endoglycosidase F. Comparison of the sequence of 244 residues thus obtained with those of 9 other legume lectins revealed extensive homologies, including 39 invariant positions and 60 partial identities. These data provide further evidence for the conservation of the lectin gene in leguminous plants.Primary sequence; Sequence homology; Lectin, legume; Glycosylation sit

Dataset for: Hepcidin in Tanzanian children with sickle cell disease

An anonymised dataset of 199 pediatric patients aged 3-18 years of age, enrolled in the prospective Muhimbili Sickle Cohort (MSC), (Makani et al. PloS ONE 2011), whose parent or guardian consented to participate, which included having blood and DNA samples archived for studies relating to understanding the pathophysiology of sickle cell disease in Tanzanian patients. The dataset contains variables on age, sex, sickle phenotype (derived from electrophoresis and high performance liquid chromatography), history of previous blood transfusion and averaged steady state hemoglobin concentrations over the previous year prior to the samples included in this analysis. Samples included in this analysis were collected at scheduled routine clinic visits at which children were assessed by the attending physician as “clinically well” with no current pain, no fever and were malaria test (smear and or rapid test) negative, and had no reported or recorded hospitalization in the previous month. Laboratory data from the analysed samples include complete blood count data, clinical chemistry values, inflammatory markers, iron markers, erythropoietin and hepcidin. Alpha thalassaemia 3.7 deletion and glucose-6-phosphate dehydrogenase deficiency as potentially disease modifying genotypes are also included

Scaffolding or Enabling? Implications of Extended Parental Financial Support into Adulthood

Recent decades have seen tremendous changes in the duration of time that parents offer financial support to their adult children. This paper explores the literature regarding the variations in support, the forces impacting those variations, and the effects of that support on the children\u27s human capital and financial attainment, as well as implications for parents. A case vignette based on an amalgam of case experiences by the authors is provided to explore the relevance of the literature findings to an amalgam financial planning client in the situation of providing financial support to an adult child. Sample interventions are based on the theoretical framework of Bowen’s family systems theory and Archuleta’s Couples and Finances Theory

Payments to Informal versus Formal Home Care Providers: Policy Divergence Affecting the Elderly and Their Families in Michigan and Illinois

State policies vary widely on paying friends and family rather than home care agencies to care for the elderly. We explore two state programs that exemplify different payment options: Michigan, which pays clients' informal caregivers, and Illinois, which generally pays agencies to provide services. We ask how different payment policies affect clients, specifically exploring program structure (division of labor and bases for need determination) and financing incentives created by Medicaid (centralization, means testing, and quality assurance). These factors shape provider and client preferences, well-being, and assessment of care quality. Comparatively, Illinois's approach favors professionalism, high cost/quality, documentation, and an orientation toward medical and physical needs. It has experienced high worker turnover and less regard for caregiver-client relationships. Michigan's approach favors informality, casual accountability, long-term stability of helping relationships, and respect for client preferences and autonomy. Both approaches offer important client benefits, but state precedents and incentives to administering agencies have shaped their overall directions. The recent rapid growth of the home care industry in Illinois could proscribe a fuller range of provider options. We recommend greater flexibility in considering states' payment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66882/2/10.1177_073346488800700403.pd

Universal Dependencies and Semantics for English and Hebrew Child-directed Speech

While corpora of child speech and child-directed speech (CDS) have enabled major contributions to the study of child language acquisition, semantic annotation for such corpora is still scarce and lacks a uniform standard. We compile two CDS corpora—in English and Hebrew—with syntactic and semantic annotations. We employ a methodology that enforces a cross-linguistically consistent representation, building on recent advances in dependency representation and semantic parsing. Our semi-automatic syntactic annotation follows the Universal Dependencies standard (UD; de Marneffe et al., 2021), adapted to suit the CDS genre. To induce semantic forms, we develop an automatic method for transducing UD structures into sentential logical forms (LFs). The two representations have complementary strengths: UD structures are language-neutral and support direct annotation, whereas LFs are neutral as to the syntax-semantics interface, and transparently encode semantic distinctions