Light scattering and random lasing in aqueous suspensions of hexagonal boron nitride nanoflakes.

Liquid phase exfoliation allows large scale production of 2D materials in solution. The particles are highly anisotropic and strongly scatter light. While spherical particles can be accurately and precisely described by a single parameter-the radius, 2D nanoflakes, however, cannot be so easily described. We investigate light scattering in aqueous solutions of 2D hexagonal boron nitride nanoflakes in the single and multiple scattering regimes. In the single scattering regime, the anisotropic 2D materials show a much stronger depolarization of light when compared to spherical particles of similar size. In the multiple scattering regime, the scattering as a function of optical path for hexagonal boron nitride nanoflakes of a given lateral length was found to be qualitatively equivalent to scattering from spheres with the same diameter. We also report the presence of random lasing in high concentration suspensions of aqueous h-BN mixed with Rhodamine B dye. The h-BN works as a scattering agent and Rhodamine B as a gain medium for the process. We observed random lasing at 587 nm with a threshold energy of 0.8 mJ.

Antithymocyte globulin (ATG)-based therapy in patients with myelodysplastic syndromes.

The purpose of this study was to determine the efficacy of and tolerance to antithymocyte globulin (ATG)-based therapy in patients with myelodysplastic syndrome (MDS). Therapy consisted of ATG 40 mg/kg/day daily intravenously (i.v.) for 4 days; cyclosporine daily orally for 6 months with levels titrated between 200 and 400 mg/dl; and methylprednisone 1 mg/kg i.v. daily before each dose of ATG. Of 32 patients treated, 31 patients were evaluable. The median age was 59 years (range, 28-79 years). A total of 18 patients had refractory anemia (RA) or RA with ringed sideroblasts (RARS), 10 patients had RA with excess blasts (RAEB), two patients had RAEB in transformation, and one patient had chronic myelomonocytic leukemia. ATG, cyclosporine, and methylprednisone induced complete (N=4) or partial (N=1) remission in five patients (16% of total; RA, two patients; RARS, two patients; and RAEB, one patient). Durable complete remissions were observed in three of 18 patients (17%) with RA (N=1) or RARS (N=2) (12, 41+, and 60+ months). The most common adverse events were fever and allergic reactions. Hepatic and renal dysfunction, albeit consistently reversible, occurred in 19 and 13% of the patients, respectively. In conclusion, an ATG-based regimen can produce durable complete remissions in a subset of patients with MDS.

Genetic analysis of mutations affecting pckA regulation in Rhizobium (Sinorhizobium) meliloti.

The enzyme phosphoenolpyruvate carboxykinase (Pck) catalyzes the first step in the gluconeogenic pathway in most organisms. We are examining the genetic regulation of the gene encoding Pck, pckA, in Rhizobium (now Sinorhizobium) meliloti. This bacterium forms N2-fixing root nodules on alfalfa, and the major energy sources supplied to the bacteria within these nodules are C4-dicarboxylic acids such as malate and succinate. R. meliloti cells growing in glucose minimal medium show very low pckA expression whereas addition of succinate to this medium results in a rapid induction of pckA transcription. We identified spontaneous mutations (rpk) that alter the regulation of pckA expression such that pckA is expressed in media containing the non-inducing carbon sources lactose and glucose. Genetic and phenotypic analysis allowed us to differentiate at least four rpk mutant classes that map to different locations on the R. meliloti chromosome. The wild-type locus corresponding to one of these rpk loci was cloned by complementation, and two Tn5 insertions within the insert DNA that no longer complemented the rpk mutation were identified. The nucleotide sequence of this region revealed that both Tn5 insertions lay within a gene encoding a protein homologous to the GalR/LacI family of transcriptional regulators that are involved in metabolism.

Neuropsychological functioning following a spinal cord injury.

Studies indicate that 10-60% of the spinal cord injury (SCI) population retains residual cognitive deficits following the injury. However, previous studies have not used a comprehensive neuropsychological battery and/or a well-matched control group. In addition, no study has determined if cognitive deficits continue more than one year after injury. The present study addressed these limitations by comparing the performance of a chronic SCI group (Mean = 17 years post-injury) and a well-matched control group in four cognitive areas. Memory, visuospatial skills, attention/executive functioning, and processing speed were assessed. Results from a discriminant function analysis indicated that information processing speed best differentiated between the SCI and control groups. Twenty-nine percent of the SCI group performed 1 to 2 standard deviations below the control group mean. These results could not be attributed to psychological status or history of alcohol consumption. The findings emphasize the importance of neuropsychological evaluation after SCI.

Department deployment: integrating quality improvement into day-to-day management.

Despite the time and resources that The George Washington University Medical Center (GWUMC) put into training and forming QI teams, QI staff found that CQI was not being used to carry out critical day-to-day departmental functions. In other words, CQI didn't affect the way staff did "real work." In response, the medical center developed an approach that integrates CQI with departmental leadership, structure, culture, and work routine. With the help of a coach, willing departments at GWUMC choose from a series of 155 activities that they complete at their own pace (eg, setting departmental CQI goals, developing a departmental mission). The department deployment process moves staff through three levels of increasing sophistication and maturity with CQI methods: awareness, understanding, and bonding. It is intended to make quality a habit for staff, or a part of the organizational mind set, rather than an isolated "project." This article will describe how the department deployment approach was developed, its philosophical underpinnings, and its methodology and tools. Then, an example will illustrate how one hospital department--social work and utilization case management--successfully used this approach.

Chronic ethanol exposure in the embryonic chick heart: effect on myocardial function and structure.

To investigate the effect of chronic ethanol exposure on the embryonic chick heart, chick embryos were exposed daily to one of seven graded doses of ethanol or to saline only (shams) from 0 to 96 hr of incubation. One hour before and after exposure at 72 hr, and 1 hr before and after exposure at 96 hr, embryos were analyzed for changes in heart function, embryo tissue ethanol content, occurrence of anomalies, and embryo weights. At both 71 and 73 hr of incubation (during cardiogenesis), when compared to shams, heart rate (HR) in embryos receiving ethanol doses greater than 0.0375 ml increased significantly (P less than .05) with commensurate increases in injected ethanol. Additionally, at 73 hr, depressed cardiac contractility, measured as shortening fraction, was noted at doses greater than or equal to .0375 when compared to shams. While slight increases in shortening fraction (SF) across dose were noted at 95 and 97 hr, only random doses were statistically significant from shams, with no specific trend in either HR or SF at this postcardiogenesis stage. Within each time group, gas chromatography analysis of embryo tissue ethanol content demonstrated a linear relationship between dose injected and tissue ethanol content retrieved. With increasing dose and stage, viability decreased. Weights of ethanol-injected embryos were not significantly different from shams within each time group. Our studies of the response of the embryonic chick heart to ethanol indicate both dose and stage susceptibility, with greater susceptibility to ethanol injury during active cardiogenesis.