California State University, Long Beach

About: California State University, Long Beach is a education organization based out in Long Beach, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 10036 authors who have published 13933 publications receiving 377394 citations. The organization is also known as: Cal State Long Beach & Long Beach State.

Inhibitory effects of a new oral gold compound on HeLa cells.

Abstract: Auranofin (AF), a recently introduced oral antirheumatic coordinated gold compound, was investigated for its antitumor potential. Due to certain similarities with the antitumor-coordinated compound, cis-Diamminedichloroplatinum II, we studied the effects of AF on cell proliferation. These studies included assessing DNA, RNA, and protein synthesis as measured by incorporation of 3H-thymidine, 3H-uridine, and 3H-leucine, respectively, into HeLa cells. AF was shown to exert a dose-dependent inhibition on DNA synthesis and to inhibit 3H-thymidine uptake more rapidly and persistently than 3H-uridine or 3H-leucine uptake at a gold concentration of 75--100 micrograms/dl. These three parameters were inhibited with a 24-hour exposure to 100 micrograms/dl. The inhibition of 3H-thymidine uptake in HeLa pretreated for 6 hours with 50 or 100 micrograms/dl of gold was found to be irreversible. No change in tracer uptake was observed in the acid-soluble pool or in the uptake of 3H-2-deoxy-D-glucose in these cells. Furthermore, HeLa cells demonstrated marked reductions in viability and oxygen uptake after exposure to AF. Dose-dependent surface morphological changes, e.g., blebbing, pitting, were noted in these cells after a brief treatment period. These results suggest this coordinated gold compount exerts a significant inhibitory effect on essential biological processes and functions.

UV Photolysis of Chloramine and Persulfate for 1,4-Dioxane Removal in Reverse-Osmosis Permeate for Potable Water Reuse

Abstract: A sequential combination of membrane treatment and UV-based advanced oxidation processes (UV/AOP) has become the industry standard for potable water reuse. Chloramines are used as membrane antifouling agents and therefore carried over into the UV/AOP. In addition, persulfate (S2O82-) is an emerging oxidant that can be added into a UV/AOP, thus creating radicals generated from both chloramines and persulfate for water treatment. This study investigated the simultaneous photolysis of S2O82- and monochloramine (NH2Cl) on the removal of 1,4-dioxane (1,4-D) for potable-water reuse. The dual oxidant effects of NH2Cl and S2O82- on 1,4-D degradation were examined at various levels of oxidant dosage, chloride, and solution pH. Results showed that a NH2Cl-to-S2O82- molar ratio of 0.1 was optimal, beyond which the scavenging by NH2Cl of HO•, SO4•-, and Cl2•- radicals decreased the 1,4-D degradation rate. At the optimal ratio, the degradation rate of 1,4-D increased linearly with the total oxidant dose up to 6 mM. The combined photolysis of NH2Cl and S2O82- was sensitive to the solution pH due to a disproportionation of NH2Cl at pH lower than 6 into less-photoreactive dichloramine (NHCl2) and radical scavenging by NH4+. The presence of chloride transformed HO• and SO4•- to Cl2•- that is less-reactive with 1,4-D, while the presence of dissolved O2 promoted gaseous nitrogen production. Results from this study suggest that the presence of chloramines can be beneficial to persulfate photolysis in the removal of 1,4-D; however, the treatment efficiency depends on a careful control of an optimal NH2Cl dosage and a minimal chloride residue.

Very high-temperature impact melt products as evidence for cosmic airbursts and impacts 12,900 years ago

Abstract: It has been proposed that fragments of an asteroid or comet impacted Earth, deposited silica-and iron-rich microspherules and other proxies across several continents, and triggered the Younger Dryas cooling episode 12,900 years ago. Although many independent groups have confirmed the impact evidence, the hypothesis remains controversial because some groups have failed to do so. We examined sediment sequences from 18 dated Younger Dryas boundary (YDB) sites across three continents (North America, Europe, and Asia), spanning 12,000 km around nearly one-third of the planet. All sites display abundant microspherules in the YDB with none or few above and below. In addition, three sites (Abu Hureyra, Syria; Melrose, Pennsylvania; and Blackville, South Carolina) display vesicular, high-temperature, siliceous scoria-like objects, or SLOs, that match the spherules geochemically. We compared YDB objects with melt products from a known cosmic impact (Meteor Crater, Arizona) and from the 1945 Trinity nuclear airburst in Socorro, New Mexico, and found that all of these high-energy events produced material that is geochemically and morphologically comparable, including: (i) high-temperature, rapidly quenched microspherules and SLOs; (ii) corundum, mullite, and suessite (Fe3Si), a rare meteoritic mineral that forms under high temperatures; (iii) melted SiO2 glass, or lechatelierite, with flow textures (or schlieren) that form at > 2,200 °C; and (iv) particles with features indicative of high-energy interparticle collisions. These results are inconsistent with anthropogenic, volcanic, authigenic, and cosmic materials, yet consistent with cosmic ejecta, supporting the hypothesis of extraterrestrial airbursts/impacts 12,900 years ago. The wide geographic distribution of SLOs is consistent with multiple impactors.

Student Persistence in Community Colleges

Abstract: The current study extends the research on student persistence in community colleges by investigating factors likely to influence a student's decision to drop out or stay in school. Specifically, this study examined demographic, financial, academic, academic integration, and psychosocial variables and their relationship to student persistence. A sample of 427 community college students completed a 63-item survey assessing psychosocial variables (i.e., self-efficacy and goals) the academic integration variable (i.e., student-faculty interaction), and a number of background variables (i.e., demographic, financial, and academic). In addition, student retention was measured through college enrollment the following semester. Results of the study revealed that age, work hours, and financial aid influenced student persistence, but the effects diminished once multiple variables were entered into the analysis. Among all the variables, cumulative GPA was the strongest predicting variable for student persistence. Stu...