16,187 research outputs found

    Copper(II)- and gold(III)-mediated cyclization of a thiourea to a substituted 2-aminobenzothiazole

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    Benzothiazole derivatives are a class of privileged molecules due to their biological activity and pharmaceutical applications. One route to these molecules is via intramolecular cyclization of thioureas to form substituted 2-aminobenzothiazoles, but this often requires harsh conditions or employs expensive metal catalysts. Herein, the copper(II)- and gold(III)-mediated cyclizations of thioureas to substituted 2-aminobenzothiazoles are reported. The single-crystal X-ray structures of the thiourea N-(3-methoxyphenyl)-N\u27- (pyridin-2-yl)thiourea, C13H13N3OS, and the intermediate metal complexes aquabis[5-methoxy-N-(pyridin-2-yl-ÎșN)-1,3-benzothiazol-2-amine-ÎșN3]copper(II) dinitrate, [Cu(C13H11N3OS)2(H2O)](NO3)2, and bis{2-[(5-methoxy-1,3-benzothiazol- 2-yl)amino]pyridin-1-ium} dichloridogold(I) chloride monohydrate, (C13H12N3OS)2[AuCl2]Cl⋅H2O, are reported. The copper complex exhibits a distorted trigonal–bipyramidal geometry, with direct metal-to-benzothiazoleligand coordination, while the gold complex is a salt containing the protonated uncoordinated benzothiazole, and offers evidence that metal reduction (in this case, AuIII to AuI) is required for the cyclization to proceed. As such, this study provides further mechanistic insight into the role of the metal cations in these transformations

    The Resonant Cavity Radiator (RCR)

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    The design of the resonant cavity radiator (RCR) is compared to that of the slotted waveguide array in terms of efficiency, weight, and structural integrity. It is shown that the RCR design has three significant potentials over the slotted waveguide array: (1) improvement in efficiency; (2) lighter weight; and (3) simpler structure which allows the RCR to be integrated with the RF tube to alleviate thermal interface problems

    Problematic Texting Behavior: A Look at Individual Differences

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    Problematic Texting Behavior: A Look at Individual Differences Bradford L. Schroeder & Valerie K. Sims University of Central Florida Text messaging (“texting”) is a communicative social behavior which is the most preferred form of social interaction among young adults (e.g., Harley et al., 2007; Haste, 2005; Lister, 2010; Sierkowski & Wood, 2011). Perhaps the greatest appeal of texting is its convenience – it is easily possible to communicate with anyone, regardless of either party’s location. However, the convenience of texting has opened a door to an important safety issue: texting while driving. The context of safety has been a prime focus for much of the recent research on texting (e.g., Drews, Yazdani, Godfrey, Cooper, & Strayer, 2009), but less attention has been focused on the consequences of other kinds of problematic texting. Although the safety implications of texting and driving are apparent, other texting behaviors may lead to adverse social, physical, health, or interpersonal consequences. Due to these potential effects, there is a need for other types of problematic texting to be better researched. In this study, we examined a variety of problematic texting behaviors in addition to those related to texting and driving, and analyzed them in the context of individual differences such as personality, need for cognition, and age. Previous work has minimally examined texting and individual differences, and because of this, the present findings are largely exploratory in nature. We argue that, to better understand a common and complex behavior such as texting, the relationships among texting behaviors and individual differences must be explored. Because young adults aged 18-25 tend to text most frequently (Ling, 2010), we surveyed 242 (55% female) undergraduate college students’ texting habits. In addition, we collected their responses to examine individual differences in age, gender, personality, and need for cognition. Generally, age showed a negative association with most of the problematic texting habits we measured, most notably texting in class, texting while walking, and texting to cheat on assignments. As compared to females, males tended to report higher rates of texting when in their vehicle (but not while driving), when bored, to send sexual messages (“sexting”), or to threaten others. Extraversion was generally positively associated with texting while driving, and neuroticism was positively associated with various socially problematic texting behaviors (such as during face-to-face conversations). These two dimensions of personality have been shown to be related to the types of text messages people send (Holtgraves, 2014). Need for cognition was negatively associated with a majority of the socially problematic texting behaviors we examined. Given that texting is more than just a social behavior, this study extends the previous research on texting with a look at less well-researched texting behaviors from an individual differences perspective. In addition to individual differences, these behaviors were examined in terms of participant endorsement rate. Participants showed high endorsement rates for dangerous behaviors, such as texting in the car when in traffic (65%), or while walking alone (89%). Further results and implications for human factors and future research are discussed

    SEASAT: A satellite scatterometer illumination times of selected in situ sites

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    A list of times that the SEASAT A Satellite Scatterometer (SASS) illuminated from directly above or directly abeam, selected surface sites where in situ winds were measured is provided. The list is ordered by the Greenwich Mean Time (GMT) of the midpoint of the illumination period (hit time) for a given surface site. The site identification, the orbit number and the direction from the subtrack in which the truth lies are provided. The accuracy of these times depends in part upon the ascending node times, which are estimated to be within +.1 sec, and on the illumination time relative to the ascending node, which is estimated to be within +6 seconds. The uncertainties in the times provided were judged to be sufficiently small to allow efficient and accurate extraction of SASS and in situ data at the selected surface sites. The list contains approximately six thousand hit times from 61 geographically dispersed sites

    Metal-Ferroelectric-Metal heterostructures with Schottky contacts I. Influence of the ferroelectric properties

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    A model for Metal-Ferroelectric-Metal structures with Schottky contacts is proposed. The model adapts the general theories of metal-semiconductor rectifying contacts for the particular case of metal-ferroelectric contact by introducing: the ferroelectric polarization as a sheet of surface charge located at a finite distance from the electrode interface; a deep trapping level of high concentration; the static and dynamic values of the dielectric constant. Consequences of the proposed model on relevant quantities of the Schottky contact such as built-in voltage, charge density and depletion width, as well as on the interpretation of the current-voltage and capacitance-voltage characteristics are discussed in detail.Comment: 14 pages with 4 figures, manuscript under revision at Journal of Applied Physics for more than 1 year (submitted May 2004, first revision September 2004, second revision May 2005

    Vacancy complexes with oversized impurities in Si and Ge

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    In this paper we examine the electronic and geometrical structure of impurity-vacancy complexes in Si and Ge. Already Watkins suggested that in Si the pairing of Sn with the vacancy produces a complex with the Sn-atom at the bond center and the vacancy split into two half vacancies on the neighboring sites. Within the framework of density-functional theory we use two complementary ab initio methods, the pseudopotential plane wave (PPW) method and the all-electron Kohn-Korringa-Rostoker (KKR) method, to investigate the structure of vacancy complexes with 11 different sp-impurities. For the case of Sn in Si, we confirm the split configuration and obtain good agreement with EPR data of Watkins. In general we find that all impurities of the 5sp and 6sp series in Si and Ge prefer the split-vacancy configuration, with an energy gain of 0.5 to 1 eV compared to the substitutional complex. On the other hand, impurities of the 3sp and 4sp series form a (slightly distorted) substitutional complex. Al impurities show an exception from this rule, forming a split complex in Si and a strongly distorted substitutional complex in Ge. We find a strong correlation of these data with the size of the isolated impurities, being defined via the lattice relaxations of the nearest neighbors.Comment: 8 pages, 4 bw figure

    Correlation of Early Outcomes and Intradiscal Interleukin-6 Expression in Lumbar Fusion Patients.

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    OBJECTIVE: To determine if there is correlation between intradiscal levels of interleukin-6 (IL-6) and early outcome measures in patients undergoing lumbar fusion for painful disc degeneration. METHODS: Intervertebral disc tissue was separated into annulus fibrosus/nucleus pulposus and cultured separately in vitro in serum-free medium (Opti-MEM). Conditioned media was collected after 48 hours. The concentration of IL-6 was quantified using enzyme-linked immunosorbent assay. Pearson correlation coefficients quantified relationships between IL-6 levels and pre- and postoperative visual analogue scale (VAS) back pain and Oswestry Disability Index (ODI), as well as change in VAS/ODI. RESULTS: Sixteen discs were harvested from 9 patients undergoing anterior lumbar interbody fusion (mean age, 47.4 years; range, 21-70 years). Mean preoperative and 6-month postoperative VAS were 8.1 and 3.7, respectively. Mean preoperative and postoperative ODI were 56.2 and 25.6, respectively. There were significant positive correlations between IL-6 expression and postoperative VAS (ρ = 0.38, p = 0.048) and ODI (ρ = 0.44, p = 0.02). No significant correlations were found between intradiscal IL-6 expression and preoperative VAS (ρ = -0.12, p = 0.54). Trends were seen associating IL-6 expression and change in VAS/ODI (ρ = -0.35 p = 0.067; ρ = -0.34, p = 0.08, respectively). A trend associated IL-6 and preoperative ODI (ρ = 0.36, p = 0.063). CONCLUSION: The direct association between IL-6 expression and VAS/ODI suggests patients with elevated intradiscal cytokine expression may have worse early outcomes than those with lower expression of IL-6 after surgery for symptomatic disc degeneration

    Effects on the immune system associated with living near a pesticide dump site.

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    In this paper, we report results of the second phase of a larger study designed to evaluate the effects on the immune system of living near a Superfund site containing organochlorine pesticides, volatile organic compounds, and metals. Phase II was conducted to determine whether living near the site, consisting of six locations in Aberdeen, North Carolina, is associated with higher plasma organochlorine levels, immune suppression, or DNA damage. Each of 302 residents of Aberdeen and neighboring communities provided a blood specimen, underwent a skin test, and answered a questionnaire. Blood specimens were analyzed for organochlorine pesticides, immune markers, and micronuclei. Of 20 organochlorines tested, only DDE was detected in the blood of participants (except for one individual). Age-adjusted mean plasma DDE levels were 4.05 ppb for Aberdeen residents and 2.95 ppb (p = 0.01) for residents of neighboring communities. Residents of 40-59 years of age who lived within a mile of any site, but particularly the Farm Chemicals site, had higher plasma DDE levels than residents who lived farther away. Residents who lived near the Farm Chemicals site before versus after 1985 also had higher plasma DDE levels. Overall, there were few differences in immune markers between residents of Aberdeen and the neighboring communities. However, residents who lived closer to the dump sites had statistically significantly lower mitogen-induced lymphoproliferative activity than residents who lived farther away (p < 0.05). Residential location was not consistently associated with frequency of micronuclei or skin test responses. Although some statistically significant differences in immune markers were noted in association with residential location, the magnitude of effects are of uncertain clinical importance

    Time-dependent fields and anisotropy dominated magnetic media

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    We use a single dipole approximation to analyze the behavior of anisotropy-dominated magnetic nanoparticles subjected to an external r.f. field. We identify the steady state oscillations and analyze their stability. We also analyze the case when the external r.f. field has a time-dependent frequency which insures the most effective switching of the magnetization
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