We report the synthesis and characterization of composition-tunable ternary lead chalcogenide alloys PbSe x Te1-x , PbS x Te1-x , and PbS x Se1-x . This work explores the relative reaction rates of ...chalcogenide precursors to produce alloyed quantum dots (QDs), and we find the highly reactive bis(trimethylsilyl) (TMS2)-based precursors allow for the homogeneous incorporation of anions. By varying the Pb to oleic acid ratio, we demonstrate size control of similar composition alloys. We find the resulting QDs are Pb-rich but the Pb/anion ratio is size- and composition-dependent in all alloyed QD as well as in PbSe, PbTe, and PbS QDs and is consistent with the reaction rates of the anion precursors. A more reactive anion precursor results in a lower Pb/anion ratio.
Background: Dual use of tobacco cigarettes and e-cigarettes ("dual use") is the most common poly-tobacco use pattern among U.S. adults. Whether dual use facilitates or inhibits smoking cessation is ...of concern, yet limited information exists regarding continuation of dual use over time. Purpose: This study examined variation in nicotine product use over a one-year period, and evaluated predictors of smoking abstinence among dual users. Methods: Data from 1,082 dual users of tobacco cigarettes and e-cigarettes were analyzed using Wave 1 (2013-2014) and Wave 2 (2014-2015) of the Population Assessment of Tobacco and Health Study. Descriptive analyses assessed variation in nicotine product use at Wave 2. Weighted logistic regression was used to identify correlates of smoking abstinence. Results: The majority of Wave 1 dual users (88.5%) continued using combustible tobacco at Wave 2: 59.2% were exclusive cigarette smokers, 25.5% remained dual users, and 3.8% reported some other combustible tobacco use pattern. The odds of being smoke-free at Wave 2 were higher among dual users who reported everyday (versus someday) e-cigarette use (aOR: 1.85; 95% CI: 1.18-2.89). Everyday use of tobacco cigarettes was inversely associated with smoking abstinence (aOR 0.33; 95% CI: 0.21-0.51). Conclusions: Over a one year period, most dual users still smoked tobacco cigarettes. Frequency of cigarette and e-cigarette use at Wave 1 were each associated with odds of smoking abstinence. Findings suggest that daily e-cigarette use may increase dual users' chances of becoming smoke free.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Binary superlattices (BSLs) of sterically stabilized, hydrophobic, large (A; 11.5 nm diameter) Fe(2)O(3) and small (B; 6.1 nm diameter) Au nanocrystals were assembled by slow evaporation of colloidal ...dispersions on tilted substrates. A detailed analysis of the BSL structure was carried out using transmission and scanning electron microscopy (TEM and SEM) and grazing incidence small-angle X-ray scattering (GISAXS). The BSLs were simple hexagonal (sh) AB(2) superlattices (isostructural with the compound AlB(2); space group 191, P6/mmm) of large nanocrystals occupying a simple hexagonal lattice with small nanocrystals in the interstitial spaces. SEM and GISAXS confirmed long-range order of the BSLs and GISAXS revealed that the superlattice is slightly contracted (8-12%) perpendicular to the substrate as a result of solvent drying in the deposition process. When the sh-AB(2) superlattice deposits on a (100) plane, this shrinkage occurs in the 210 direction and changes the lattice symmetry to centered orthorhombic. Additionally, nearly periodic superlattice dislocations consisting of inserted half-planes of gold nanocrystals were observed by SEM in some BSLs.
Despite vaccines’ effectiveness in reducing the rate of preventable diseases, vaccine hesitancy has threatened public health and economies worldwide. Healthcare providers’ (HCP) communications and ...behavior strongly influence patient receptivity and uptake. The goal of this review was to examine HCP vaccine perceptions, knowledge, and reservations and how these attitudes affect their recommendations and vaccination practices. Primary research studies published by 16 September 2020 were searched in PubMed, Web of Science, Embase, CINAHL, and PsycINFO. A 14-item scale was developed for survey study and risk of bias appraisal (SSRBA). In total, 96 papers from 34 countries were included, covering 17 vaccines (HPV and influenza vaccines the most studied). Recommendation was positively associated with provider knowledge and experience, beliefs about disease risk, and perceptions of vaccine safety, necessity, and efficacy. HCP vaccination attitudes and practices varied across specialties, vaccines, and countries; demographic impact was inconclusive. Barriers included anticipation of patient/parental concerns or refusal, lacking clear guidelines, time constraints, and cost. For HPV, vaccines were more often recommended to older, female adolescents and by physicians who discussed sexual health. HCPs are vital advocates for patients and the public, but studies indicated a prevalence of provider hesitancy pertaining to inadequate knowledge, low vaccine confidence, and suboptimal uptake themselves. Improving HCP knowledge and assuring their access to information they deem trustworthy are essential to supporting HCPs‘ role as “trusted messengers” to promote vaccine acceptance.
Mitochondrially mediated apoptosis is characterized by redistribution of proteins from mitochondria to cytoplasm following permeabilization of the outer mitochondrial membrane. We applied flow ...cytometry to quantify simultaneously the redistribution of two apoptogenic proteins, cytochrome c (cyt c) and Smac/DIABLO (Smac). Mammalian cells were treated with digitonin that selectively permeabilizes the plasma membrane. Following fixation, treated cells were infused successively with primary and secondary antibodies (the latter fluorescently tagged) enabling independent detection of cyt c and Smac. Digitonin-treated cells that retain cyt c or Smac in mitochondria generate strong fluorescence signals in flow cytometry. Cells in which cyt c or Smac have transited the outer mitochondrial membrane show greatly reduced fluorescence because the proteins are lost from the digitonin-permeabilized cells. Quantitative flow cytometry revealed that in 143B TK(-) cells treated with staurosporine, cyt c and Smac exit mitochondria asymmetrically, with cyt c redistribution preceding that of Smac. However, in HeLa cells likewise treated, cyt c and Smac exit mitochondria concurrently. Under other conditions of apoptotic induction, for example, 143B TK(-) cells treated with MT-21 (an apoptotic inducer that binds to the mitochondrial adenine nucleotide transporter), redistribution of Smac precedes that of cyt c. The various patterns of redistribution of these proteins were confirmed by immunocytochemical analysis and confocal microscopy. We conclude that flow cytometry can be employed effectively to quantify simultaneously the redistribution of cyt c and Smac from mitochondria to the cytosol. Moreover, differential redistribution of cyt c and Smac occurs under various conditions, thereby reflecting constraints on availability of these proteins to exit mitochondria after permeabilization of the outer membrane.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The red-brown (WSCl4)2{μ-RS(CH2)2SR} (R = Me, Ph, iPr) and (WSCl4)2{μ-MeS(CH2)3SMe} have been made by reaction of WSCl4 with the thioether in a 2 : 1 molar ratio, in anhydrous CH2Cl2 solution, and ...characterised by microanalysis, IR, UV/Vis and 1H NMR spectroscopy. The X-ray structures of the four dithioether complexes reveal square pyramidal WSCl4 units and bridging dithioethers with W=S trans to thioether sulfur. Paramagnetic W(v) complexes, WSCl3{RS(CH2)2SR} (R = Me, iPr), have been made similarly using a 1 : ≥1 ratio of reactants or longer reaction times. The W(vi) complexes, WSCl4(SMe2) and WSCl4(SeMe2), are also described. Analogous complexes of WOCl4, (WOCl4)2{RS(CH2)2SR} (R = Ph, iPr), have been made similarly from WOCl4, but reactions using MeS(CH2)nSMe (n = 2, 3) led to reduction to W(v), forming WOCl3{MeS(CH2)nSMe, both of which were identified crystallographically. Curiously, they are geometric isomers: WOCl3{MeS(CH2)3SMe} has the dithioether trans Cl/Cl whereas in WOCl3{MeS(CH2)2SMe} it is trans O/Cl. Remarkably, low pressure chemical vapour deposition (CVD) experiments using the dinuclear W(vi) species, (WSCl4)2{iPrS(CH2)2SiPr}, as a single source precursor produced thin films of 4H-WS2, identified by grazing incidence X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy; the tungsten thiochloride complex is the first single source low pressure CVD precursor for WS2. In contrast, the mononuclear W(v) complex, WSCl3{iPrS(CH2)2SiPr}, does not deposit WS2 under similar conditions.
Salmonella is able to survive in low-moisture environments and is known to be more heat resistant as product water activity (aw) decreases. However, it is unknown how rapidly the resistance changes ...if product aw is altered rapidly, as can occur in certain processes. Therefore, the objective was to determine the effect of rapid product desiccation or hydration on Salmonella thermal resistance. Two dynamic moisture treatments were compared with two static moisture treatments to determine the effect of time-at-moisture on the thermal resistance of Salmonella enterica serovar Enteritidis phage type 30 (PT 30) in wheat flour. After inoculation, two static moisture groups were equilibrated to 0.3 and 0.6 aw over 4 to 7 days, and two dynamic moisture groups then were rapidly (<4 min) desiccated from 0.6 to 0.3 aw or hydrated from 0.3 to 0.6 aw. Samples then were subjected to isothermal (80°C) heat treatments, and Salmonella thermal resistance was compared via decimal reduction times (i.e., D80°C-values). The D80°C-value in flour that was rapidly desiccated from 0.6 to 0.3 aw was statistically equivalent (P > 0.05) to the D80°C-value in flour previously equilibrated to 0.3 aw, but both were greater (P < 0.05) than the D80°C-value in flour previously equilibrated to 0.6 aw. Similarly, the D80°C-value in flour rapidly hydrated from 0.3 to 0.6 aw was statistically equivalent (P > 0.05) to the D80°C-value in flour previously equilibrated to 0.6 aw, and both were less than the D80°C-value in flour previously equilibrated to 0.3 aw. Therefore, Salmonella in the rapidly desiccated flour (0.3 aw) was as thermally resistant as that which previously had been equilibrated to 0.3 aw, and Salmonella in the rapidly hydrated flour (0.6 aw) responded similarly to that in the flour previously equilibrated to 0.6 aw. These results suggest that the response period to new aw is negligible, which is critically important in applying thermal resistance data or parameters to industrial pasteurization validations.
This study examined whether nontobacco flavors are more commonly used by vapers (e-cigarette users) compared with tobacco flavor, described which flavors are most popular, and tested whether flavors ...are associated with: vaping satisfaction relative to smoking, level of enjoyment with vaping, reasons for using e-cigarettes, and making an attempt to quit smoking by smokers.
This cross-sectional study included 1603 adults from Canada and the United States who vaped at least weekly, and were either current smokers (concurrent users) or former smokers (exclusive vapers). Respondents were categorized into one of seven flavors they used most in the last month: tobacco, tobacco-menthol, unflavored, or one of the nontobacco flavors: menthol/mint, fruit, candy, or "other" (eg, coffee).
Vapers use a wide range of flavors, with 63.1% using a nontobacco flavor. The most common flavor categories were fruit (29.4%) and tobacco (28.7%), followed by mint/menthol (14.4%) and candy (13.5%). Vapers using candy (41.0%, p < .0001) or fruit flavors (26.0%, p = .01) found vaping more satisfying (compared with smoking) than vapers using tobacco flavor (15.5%) and rated vaping as very/extremely enjoyable (fruit: 50.9%; candy: 60.9%) than those using tobacco flavor (39.4%). Among concurrent users, those using fruit (74.6%, p = .04) or candy flavors (81.1%, p = .003) were more likely than tobacco flavor users (63.5%) to vape in order to quit smoking. Flavor category was not associated with the likelihood of a quit attempt (p = .46). Among exclusive vapers, tobacco and nontobacco flavors were popular; however, those using tobacco (99.0%) were more likely than those using candy (72.8%, p = .002) or unflavored (42.5%, p = .005) to vape in order to stay quit.
A majority of regular vapers in Canada and the US use nontobacco flavors. Greater satisfaction and enjoyment with vaping are higher among fruit and candy flavor users. While it does not appear that certain flavors are associated with a greater propensity to attempt to quit smoking among concurrent users, nontobacco flavors are popular among former smokers who are exclusively vaping. Future research should determine the likely impact of flavor bans on those who are vaping to quit smoking or to stay quit.
Recent concerns about the attractiveness of e-cigarette flavors among youth have resulted in flavor restrictions in some jurisdictions of the United States and Canada. However, little is known about the possible consequences for current and former smokers if they no longer have access to their preferred flavors. This study shows that a variety of nontobacco flavors, especially fruit, are popular among adult vapers, particularly among those who have quit smoking and are now exclusively vaping. Limiting access to flavors may therefore reduce the appeal of e-cigarettes among adults who are trying to quit smoking or stay quit.
Introduction: Use of electronic cigarettes (e-cigarettes) is frequently promoted as a less harmful alternative to cigarette smoking. The impact of repeated inhalation of e-cigarette aerosols on ...respiratory health is not well understood.
Areas covered: Using results from laboratory, observational, and clinical studies, we synthesize evidence relevant to potential respiratory health effects that may result from inhalation of e-cigarette aerosols.
Expert commentary: Chemical analyses reveal that e-cigarette aerosols contain numerous respiratory irritants and toxicants. There are documented cytotoxic effects of e-cigarette constituents on lung tissue. Studies among ex-smokers who switched to e-cigarettes note reduced exposure to numerous respiratory toxicants, reduced asthma exacerbations, and chronic obstructive pulmonary disease symptoms. Regular exposure to e-cigarette aerosols is associated with impaired respiratory functioning. Potential respiratory health risks resulting from secondhand e-cigarette aerosol exposure have not been sufficiently evaluated. Current evidence indicates that although e-cigarettes are not without risk, these products seemingly pose fewer respiratory health harms issues compared to tobacco cigarettes. Data from prospective studies and randomized controlled trials examining the impact of e-cigarette use on lung health are needed to better understand respiratory health risks tied to use of these products.
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