The mechanisms and process of acephate degradation by hydroxyl radical and hydrated electron

The degradation process of acephate in aqueous solution with ^•OH and eaq− produced by ⁶⁰Co-γ irradiation and electron pulse radiolysis was studied in the present paper. In the aqueous solution, acephate reacted with eaq− and transformed to transient species which can absorb weakly in the wavelength range of 300–400 nm and decay very fast. According to the decay of hydrated electron, the reaction rate constant of eaq− and acephate is (3.51 ± 0.076) × 10⁹ dm³·mol⁻¹·s⁻¹. The transient species produced in the reaction of ^•OH and acephate do not distinctly absorb the light in the wavelength range of 300–700 nm, so the decay and kinetics of the transient species cannot determinedirectly. The competing reaction of KSCN oracephate with ^•OH were studied to obtain the reaction rate constant of ^•OH and acephate, which is (9.1 ± 0.11) × 10⁸ dm³·mol⁻¹·s⁻¹. Although acetylamide and inorganic ions were determined in the products of the reaction of acephate with ^•OH or eaq−, the concentration of inorganic ions in the products of the reaction of acephate with ^•OH is higher than that in the product of the reaction of acephate with eaq−. Moreover, there were sulfide in the products of the reaction of acephatewith eaq−. The degradation pathways of acephate by ^•OH and eaq− were also proposed based on the products from GC-MS.

Enhancement of random lasing based on the composite consisting of nanospheres embedded in nanorods template

A simple and general approach has been developed for the enhancement of random lasing based on the composite consisting of nanospheres and nanorods array. Due to the inherent nature of high refractive index, the selected nanorods act efficiently as scattering feedback centers, which can promote the formation of closed loop paths of the emission arising from nanospheres. To illustrate our working principle, the composite consisting of Tb(OH)(3)/SiO(2) nanospheres and ZnO nanorods was chosen as an example. Quite interestingly, it is found that the random lasing behavior can be easily achieved for the composite system, while it is absent in pure Tb(OH)(3)/SiO(2) nanospheres. The strategy demonstrated here should be very useful for the future development of coherent light emission sources and many other optoelectronic devices.

Laser action in Tb(OH)3/SiO2 photonic crystals

Photonic crystals of Tb(OH)(3)/SiO(2) core/shell nanospheres with different periodicities were used as a resonant cavity to explore laser action. By changing the particle size, the optical stop band of the photonic crystals can be tuned to coincide with the multiple emission bands of terbium ions. An overlap of the stop band on the multiple emissions of the active materials embedded inside the photonic crystals offered a good chance for resonance. Lasing emissions arising from terbium ions occurred near the band edge of the PCs were demonstrated.

Asian American college students as model minorities: an examination of their overall competence

Educational success among Asian Americans has led to their being labeled the "model minority." At the University of California, Berkeley (UCB), Asian American students have higher grade point averages (GPAs) than Hispanic and African American but not White students, supporting the notion that Asian Americans are more successful compared with other racial minorities. However, success in the classroom does not implicate effective functioning in life, and nonacademic criteria ought to be considered in assessing the validity of the model minority image. Given the increasing diversification of the United States, cross-racial engagement may be an additional contributor to overall competence. This was empirically tested in a group of 642 undergraduates at UCB, including 291 Asian, 197 White, 20 African American, 67 Hispanic, and 56 multiracial students. Overall competence was operationalized by sense of coherence, that is, the extent to which the world is experienced as comprehensible, manageable, and meaningful (A. Antonovsky, 1979, 1987). As predicted, Asian Americans had significantly fewer numbers of cross-racial groups represented in their friendship network than did students of all other races. Lower cross-racial engagement and being Asian (as compared with White) were related to a lower sense of coherence, whereas lower GPA was not. Within the Asian American subsample, cross-racial engagement was again significantly associated with greater coherence, whereas GPA again was not. Thus, extending the definition of success to overall competence, these findings raise questions about the applicability of the model minority label to Asian Americans, despite their academic achievement. Future studies need to assess the reasons for their limited cross-racial engagement and lower sense of coherence and to examine means to assist the development of these strengths.

Improved retroviral transduction of hematopoietic progenitors by combining methods to enhance virus-cell interaction

One of the factors required for successful retroviral transduction is contact between viral particles and target cells. We hypothesized that combining agents that improve virus-target cell interaction via different mechanisms will increase transduction efficiency. We examined the transduction efficiency of leukemic K562 cells, primary normal and chronic myelogenous leukemia CD34+ cells with the amphotropic retroviral vector, G1Na, packaged in PA317 by enumerating G418-resistant colonies in semisolid media. We evaluated the ability of the recombinant fibronectin fragment, CH296, cationic lipids, or a transwell flow-through system, alone or in combination to improve retroviral transduction. Transduction of K562 cells improved 1.5 to two-fold with lipids or CH296, while their combination improved transduction 2.5-fold. Transduction of K562 cells in the transwell flow-through system improved transduction three-fold. Transduction of normal (NL) CD34+ CFC improved 10-fold with lipids and 20-fold with CH296. Lipid and CH296 had synergistic effects. The transwell flow-through system improved transduction of normal CD34+ CFC 30-fold. Finally, similar to what was seen for K562 cells, transduction of CML CFC improved two- to three-fold with either CH296 or lipids, whereas the combination had synergistic effects. We conclude that any physical means that enhances contact between viral particles and target cells improves transduction. Two such methods that have different action mechanisms have additive or synergistic effects on transduction.

Bacterial Streak and Bulb Rot of Onion: I. A Diagnostic Medium for the Semiselective Isolation and Enumeration of Pseudomonas viridiflava

A semiselective, diagnostic agar medium (T-5) and low temperature incubation technique were developed for recovering Pseudomonas viridiflava from the environment or plant material. Medium T-5 contains the following per liter: NaCl, 5.0 g; NH₄H₂PO₄, 1.0 g; K₂HPO₄, 1.0 g; MgSO₄·H₂O, 0.2 g; D-tartaric acid, 3.0 g; phenol red, 0.01 g; agar, 20.0 g; bacitracin, 10 mg; vancomycin, 6 mg; cycloheximide, 75 mg; novobiocin, 45 mg; penicillin G, 5 mg. The pH is adjusted to 7.4. Antibiotics are added aseptically after autoclaving. P. viridiflava recovery from artificially infested, field-soil (Tifton loamy-sand), with a cropping history of no onion production, was high, with a corresponding reduction of 99.99% of nontarget bacteria. However, soils from fields with a long history of onion production, near Vidalia, Georgia, contained significantly larger populations of background microflora that grew on medium T-5. Incubation at 5°C reduced contaminating microflora 1,000- to 10,000-fold with no reduction in recovery of the target organism. However, this low temperature incubation required an increased incubation period of 3 weeks and reduced the level of fluorescence of P. viridiflava.

Bilateral retinal responses during the acute phase (4-14 days) after traumatization of a single eye in the mouse

The infiltration of T lymphocytes and macrophages was examined in the retinae of traumatized and non-traumatized contra-lateral eyes of mice. Traumatization was produced by channeling a small hole in the limbic region of a single eye in each animal while it was under Nembutal anesthesia and a small piece of iron wire was inserted into the eye. After the T lymphocytes and macrophages were made apparent by immuno-histochemistry, they were counted on sectioned strips of the peripheral retinae 250 micrometer in length in both traumatized and non-traumatized eyes. During the first two weeks after the induced disturbance, both the retinae of the traumatized and non-traumatized eyes showed infiltration of T lymphocytes and macrophages. Although this increase in T lymphocyte infiltration was observed in both damaged eye and the undamaged one, the former displayed an enhanced increase. The contrary was noticed for macrophages infiltrating the undamaged eye. A bilateral response was therefore evident through the cellular infiltration in the traumatized and un-traumatized eyes. Morphometrical observations also revealed nuclear size changes in the retina during this acute phase of traumatization.