Inactivation of the bacterial pathogens Staphylococcus pseudintermedius and Acinetobacter baumannii by butanoic acid.

AIMS: This study was performed to evaluate the efficacy of butanoic acid against bacterial pathogens including Acinetobacter baumannii and Staphylococcus pseudintermedius. METHODS AND RESULTS: Vegetative bacteria were exposed to butanoic acid in vitro and log reduction was quantified using viable count assays. The maximum (8 and 9) log inactivation was determined by qualitatively assaying for growth/no-growth after a 48-h incubation (37°C). Membrane integrity after exposure to butanoic acid was determined by propidium iodide staining, scanning electron microscopy, membrane depolarization and inductively coupled plasma analysis. Cytosolic pH was measured by 5-(6-)carboxyfluorescein succinimidyl ester. CONCLUSIONS: Inhibitory concentrations of butanoic acid ranged between 11 and 21 mmol l-1 for Gram-positive and Gram-negative species tested. The maximum log reduction of A. baumannii was achieved with a 10-s exposure of 0·50 mol l-1 of butanoic acid. Staphylococcus pseudintermedius required 0·40 mol l-1 of butanoic acid to achieve the same level of reduction in the same time period. Inactivation was associated with membrane permeability and acidification of the cytosol. SIGNIFICANCE AND IMPACT OF THE STUDY: Antibiotic resistance among bacterial pathogens necessitates the utilization of novel therapeutics for disinfection and biological control. These results may facilitate the development of butanoic acid as an effective agent against a broad-spectrum of antibiotic-resistant bacterial pathogens.

85.7 MHz repetition rate mode-locked semiconductor disk laser: fundamental and soliton bound states.

Mode-locked optically pumped semiconductor disk lasers (SDLs) are in strong demand for applications in bio-medical photonics, chemistry, space communications and non-linear optics. However, the wider spread of SDLs was constrained as they are operated in high repetition rates above 200 MHz due to short carrier lifetimes in the semiconductors. Here we demonstrate experimentally and theoretically that it is possible to overcome the limitation of fast carrier relaxation and show significant reduction of repetition rate down to 85.7 MHz by exploiting phase-amplitude coupling effect. In addition, a low repetition rate SDL serves as a test-bed for bound soliton state previously unknown for semiconductor devices. The breakthrough to sub-100 MHz repetition rate will open a whole new window of development opportunities.

High-power quantum-dot-based semiconductor disk laser.

We demonstrate multiwatt cw output power from an optically pumped quantum-dot semiconductor disk laser. Continuous-wave output power of 4.35 W with 22% slope efficiency was demonstrated at a center wavelength of 1,032 nm. This represents an increase in power of 15 times and an increase in slope efficiency of 10 times from the previously published results using Stranski-Krastanow grown quantum dots. An intracavity diamond heat spreader was used for thermal management. The maximum output power was limited by the available pump power, and no sign of thermal rollover was observed.

Carrier recombination under one-photon and two-photon excitation in GaN epilayers.

Luminescence properties of 100-mum thick GaN epilayers grown by hydride vapor phase epitaxy (HVPE) over three different substrates: high-pressure grown n-type bulk GaN (HP-n-GaN), high-pressure bulk GaN doped with magnesium (HP-GaN:Mg), and free-standing HVPE lifted-off from sapphire (FS-HVPE-GaN), were compared by means of one-photon and two-photon excitations. The contribution of carrier capture to nonradiative traps was estimated by the analysis of luminescence transients with carrier diffusion taken into account. The estimated values of carrier lifetime of about 3ns and diffusion coefficient of 1cm(2)/s indicate the highest quality of GaN epilayers on FS-HVPE-GaN substrates.

Psychosocial factors associated with urban adolescent female suicide attempts.

This study identified psychosocial factors that differentiated 19 adolescent female suicide attempters from 21 demographically similar nonattempters in a low income, urban area. Adolescents and their parents independently completed questionnaires and participated in structured and semistructured interviews. Attempters expressed significantly higher levels of suicidal ideation and were described by their parents as displaying higher levels of depressed mood and delinquent behavior problems than nonattempters. Attempters also identified fewer support persons, were less likely to be living with their mothers, were less likely to describe confiding relationships with parents/guardians, and had less active and affectionate relationships with mother figures than nonattempters. Finally, attempters reported more undesirable life stresses than nonattempters.

A methodological consideration in the construction of actuarial interpretation systems.

Several actuarial interpretive systems have been constructed utilizing medical records as the source of criterion data. The present study compared adjective frequencies tabulated on a 100-item checklist from two samples of behaviorally disturbed children and adolescents employing different data collection procedures. Frequencies for the medical record sample (n = 79) were obtained by raters who reviewed case history materials and completed the checklist. The checklist sample (n = 79) was comprised of subjects matched on sex, age, and race and on whom the checklist was completed following a diagnostic evaluation. Significant differences in adjective frequencies were obtained on more than one-third of the items. When descriptors reflected syndrome-specific behaviors, minimal or no differences were found. However, consistent under-reporting of less diagnostically specific though clinically relevant characteristics was indicated in the medical record sample. This was attributed to the lack of systematic review of potential correlates. The implications for the development of actuarial systems, conduct of retrospective investigations, and construction of empirical classification systems based on medical record data were discussed.

Objective personality assessment of children: an exploratory study of the Personality Inventory for Children (PIC) in a child psychiatric setting.

Some initial data are presented on the clinical utility of a new multidimensional objective personality inventory, the Personality Inventory for Children (PIC), Tabulation of symptoms and family characteristics independently derived from the chart data generated by 79 preadolescent outpatient evaluations resulted in an average of 12 correlates for each of the 16 profile scales. These correlates provided substantial support for the basic interpretive intent of at least 14 of these scales, as well as additional serendipitous construct validity in the form of PIC scale-parent descriptor relationships. The presentation of case findings of two adolescents with dissimilar PIC profiles demonstrated the potential value of this diagnostic instrument.