32 research outputs found
Comparison of Methods of Measuring Electronic Cigarette Puff Topography
To evaluate properly the potential benefits and harms of electronic cigarettes (ECIGs), it is important to evaluate how individuals puff from an electronic cigarette, or their puff topography. This measure, which includes indices of puff number, duration, volume, interpuff interval, and flow rate, can be used to predict exposure to toxicants including nicotine. Puff topography has been studied extensively for cigarette smokers, but not ECIG users. The studies that have involved electronic cigarette topography measurement have done so using devices that have not been thoroughly validated or proven reliable. Thus, the purpose of this study was to evaluate methods of measuring electronic cigarette puff topography. Twelve participants (seven ECIG-experienced users, five ECIG-naive cigarette smokers) completed three Latin-square ordered sessions that differed by topography measurement method: eTop 2.0, eTop, or natural observation via video recording. Following â„ 12 hours of nicotine/tobacco abstinence, participants engaged in three bouts of ECIG puffing: one 10-puff directed bout and two ad lib bouts. Additionally, subjective ratings of nicotine/tobacco withdrawal and product effects were evaluated before and after each ECIG bout. Puff topography did not differ between measurement methods or between groups (p\u27s \u3e 0.05). Measurement of smoking topography differed little between the mouthpiece-based device and direct observation methods. Puff duration, number, and IPI were correlated highly across measurement methods (all r\u27s \u3e 0.68). All methods were also reliable, as demonstrated by high correlations across cigarette bouts within each condition (most r\u27s \u3e 0.78). Ratings of withdrawal and product effects changed from baseline to post-directed bout and post-ad lib bout, potentially suggesting nicotine delivery from the electronic cigarette. Due to the low sample size, definitive conclusions cannot be determined from this study. Further research should continue to evaluate these measurements with a sample size appropriately powered to detect differences between measurement methods and groups
Short-term abstinence effects in experienced electronic cigarette users
Nicotine/tobacco dependence is a problem that negatively affects health at an individual and population level. Nicotine/tobacco dependence may be best assessed by measuring withdrawal symptoms of a nicotine/tobacco user who abstains from use. Withdrawal symptoms experienced by cigarette smokers are well characterized, including deficits in attention and memory, as well as self-reported cravings, urges, and other symptoms. While withdrawal in cigarette smokers has been studied extensively, little is known about dependence and withdrawal associated with newer products, such as electronic cigarettes (ECIGs). ECIGs can deliver nicotine comparably to tobacco cigarettes, indicating that they may have the potential to cause dependence. However, extant work assessing ECIG dependence and withdrawal is confounded by current or previous cigarette smoking in ECIG users. Thus, the purpose of this project was to characterize cognitive, subjective, and physiological measures of ECIG withdrawal in ECIG users who are not regular cigarette smokers. Eleven ECIG users that were primarily nonsmokers participated in two, 3.5-hour sessions that differed by ECIG use: 180 minutes ad lib ECIG use and 180 minutes abstinent. Outcome measures included subjective questionnaires of withdrawal and nicotine effects, heart rate, cognitive assessments of sustained attention, working memory, and inhibitory control, and ECIG reward. Participants subjectively reported more craving, urges, and desire to vape at 120 to 180 minutes of abstinence compared to baseline. Participants also had poorer accuracy on an inhibitory control task at 120 minutes of abstinence compared to baseline abstinence or 120 minutes of ad lib ECIG use. Additional analyses included assessing characteristics that predict ECIG dependence, characterizing ad lib puff topography, and predicting withdrawal based on puff topography. Higher nicotine concentrations, daily ECIG use, longer durations of ECIG use, and higher wattages were associated with increased nicotine dependence. Results of this study demonstrate preliminary evidence of short-term withdrawal in ECIG users that are primarily nonsmokers, though findings are limited by a small sample size. Future research should be continue with similar experimental designs but increase sample size and assess longer durations of abstinence to better characterize ECIG withdrawal and dependence
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WIPP Gas-Generation Experiments
An experimental investigation was conducted for gas generation in contact-handled transuranic (CH TRU) wastes subjected for several years to conditions similar to those expected to occur at the Waste Isolation Pilot Plant (WIPP) should the repository eventually become inundated with brine. Various types of actual CH TRU wastes were placed into 12 corrosion-resistant vessels. The vessels were loosely filled with the wastes, which were submerged in synthetic brine having the same chemical composition as that in the WIPP vicinity. The vessels were also inoculated with microbes found in the Salado Formation at WIPP. The vessels were sealed, purged, and the approximately 750 ml headspace in each vessel was pressurized with nitrogen gas to approximately 146 atmospheres to create anoxic conditions at the lithostatic pressure estimated in the repository were it to be inundated. The temperature was maintained at the expected 30°C. The test program objective was to measure the quantities and species of gases generated by metal corrosion, radiolysis, and microbial activity. These data will assist in the specification of the rates at which gases are produced under inundated repository conditions for use in the WIPP Performance Assessment computer models. These experiments were very carefully designed, constructed, instrumented, and performed. Approximately 6 1/2 years of continuous, undisturbed testing were accumulated. Several of the vessels showed significantly elevated levels of generated gases, virtually all of which was hydrogen. Up to 4.2% hydrogen, by volume, was measured. Only small quantities of other gases, principally carbon dioxide, were detected. Gas generation was found to depend strongly on the waste composition. The maximum hydrogen generation occurred in vessels containing carbon steel. Visual examination of carbon-steel coupons confirmed the correspondence between the extent of observable corrosion and hydrogen generation. Average corrosion penetration rates in carbon-steel of up to 2.3 microns per year were deduced. Conversion of carbon to carbon dioxide was calculated to be as high as 4.7 ”g mol/yr/g carbon. Carbon monoxide was detected in only two waste compositions, and methane was detected in only one. In all three of these cases, the concentrations of these lesser gases detected were barely above the detection limits. No hydrogen sulfide was ever detected. Initial rates of hydrogen generation measured in the carbon-steel-bearing wastes during the first year of testing did not always correspond to rates measured over the longer term. Compared to the long-term trends, the initial gas-generation rates for some waste types were higher, for some lower, and for others remained constant. Although carbon-steel corrosion was clearly the dominant hydrogen generator, the rates of generation were found to be reduced in test vessels where the same quantity of carbon steel was co-mingled with other waste types. This is a beneficial phenomenon relative to performance of the WIPP repository. Statistical analyses of the results were made to quantify these negative interaction effects. Electron microscopy analyses of the carbon-steel coupons revealed that corrosion products were predominantly iron chlorides and oxides. Iron, chlorine, oxygen, uranium, magnesium, calcium, aluminum, silicon were all present in the corrosion products. No americium nor neptunium, both present in the wastes, were detected in any of the corrosion products. Al
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Argonne-West facility requirements for a radioactive waste treatment demonstration
At Argonne National Laboratory-West (ANL-W), near Idaho Falls, Idaho, facilities that were originally constructed to support the development of liquid-metal reactor technology are being used and/or modified to meet the environmental and waste management research needs of DOE. One example is the use of an Argonne-West facility to conduct a radioactive waste treatment demonstration through a cooperative project with Science Applications International Corporation (SAIC) and Lockheed Idaho Technologies Company. The Plasma Hearth Process (PBP) project will utilize commercially-adapted plasma arc technology to demonstrate treatment of actual mixed waste. The demonstration on radioactive waste will be conducted at Argonne`s Transient Reactor Test Facility (TREAT). Utilization of an existing facility for a new and different application presents a unique set of issues in meeting applicable federal state, and local requirements as well as the additional constraints imposed by DOE Orders and ANL-W site requirements. This paper briefly describes the PHP radioactive demonstrations relevant to the interfaces with the TREAT facility. Safety, environmental design, and operational considerations pertinent to the PHP radioactive demonstration are specifically addressed herein. The personnel equipment, and facility interfaces associated with a radioactive waste treatment demonstration are an important aspect of the demonstration effort. Areas requiring significant effort in preparation for the PBP Project being conducted at the TREAT facility include confinement design, waste handling features, and sampling and analysis considerations. Information about the facility in which a radioactive demonstration will be conducted, specifically Argonne`s TREAT facility in the case of PHP, may be of interest to other organizations involved in developing and demonstrating technologies for mixed waste treatment
Structural brain correlates of childhood inhibited temperament: an ENIGMA-Anxiety Mega-analysis
NWORubicon 019.201SG.022Pathways through Adolescenc
Electronic cigarettes for smoking cessation
Background Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol formed by heating an eâliquid. Some people who smoke use ECs to stop or reduce smoking, but some organizations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit and if they are safe to use for this purpose. This is an update of a review first published in 2014. Objectives To examine the effectiveness, tolerability, and safety of using electronic cigarettes (ECs) to help people who smoke achieve longâterm smoking abstinence. Search methods We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 February 2021, together with referenceâchecking and contact with study authors. Selection criteria We included randomized controlled trials (RCTs) and randomized crossâover trials in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. To be included, studies had to report abstinence from cigarettes at six months or longer and/or data on adverse events (AEs) or other markers of safety at one week or longer. Data collection and analysis We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months followâup, adverse events (AEs), and serious adverse events (SAEs). Secondary outcomes included changes in carbon monoxide, blood pressure, heart rate, blood oxygen saturation, lung function, and levels of known carcinogens/toxicants. We used a fixedâeffect MantelâHaenszel model to calculate the risk ratio (RR) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data from these studies in metaâanalyses. Main results We included 56 completed studies, representing 12,804 participants, of which 29 were RCTs. Six of the 56 included studies were new to this review update. Of the included studies, we rated five (all contributing to our main comparisons) at low risk of bias overall, 41 at high risk overall (including the 25 nonârandomized studies), and the remainder at unclear risk. There was moderateâcertainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (risk ratio (RR) 1.69, 95% confidence interval (CI) 1.25 to 2.27; I2 = 0%; 3 studies, 1498 participants). In absolute terms, this might translate to an additional four successful quitters per 100 (95% CI 2 to 8). There was lowâcertainty evidence (limited by very serious imprecision) that the rate of occurrence of AEs was similar) (RR 0.98, 95% CI 0.80 to 1.19; I2 = 0%; 2 studies, 485 participants). SAEs occurred rarely, with no evidence that their frequency differed between nicotine EC and NRT, but very serious imprecision led to low certainty in this finding (RR 1.37, 95% CI 0.77 to 2.41: I2 = n/a; 2 studies, 727 participants). There was moderateâcertainty evidence, again limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to nonânicotine EC (RR 1.70, 95% CI 1.03 to 2.81; I2 = 0%; 4 studies, 1057 participants). In absolute terms, this might again lead to an additional four successful quitters per 100 (95% CI 0 to 11). These trials mainly used older EC with relatively low nicotine delivery. There was moderateâcertainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 3 studies, 601 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 0.60, 95% CI 0.15 to 2.44; I2 = n/a; 4 studies, 494 participants). Compared to behavioral support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.70, 95% CI 1.39 to 5.26; I2 = 0%; 5 studies, 2561 participants). In absolute terms this represents an increase of seven per 100 (95% CI 2 to 17). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was no evidence that the rate of SAEs differed, but some evidence that nonâserious AEs were more common in people randomized to nicotine EC (AEs: RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low certainty; 4 studies, 765 participants; SAEs: RR 1.17, 95% CI 0.33 to 4.09; I2 = 5%; 6 studies, 1011 participants, very low certainty). Data from nonârandomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued use. Very few studies reported data on other outcomes or comparisons and hence evidence for these is limited, with confidence intervals often encompassing clinically significant harm and benefit. Authors' conclusions There is moderateâcertainty evidence that ECs with nicotine increase quit rates compared to ECs without nicotine and compared to NRT. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the size of effect, particularly when using modern EC products. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, though evidence indicated no difference in AEs between nicotine and nonânicotine ECs. Overall incidence of SAEs was low across all study arms. We did not detect any clear evidence of harm from nicotine EC, but longest followâup was two years and the overall number of studies was small. The evidence is limited mainly by imprecision due to the small number of RCTs, often with low event rates. Further RCTs are underway. To ensure the review continues to provide upâtoâdate information, this review is now a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status
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Development and Application of an Analysis Methodology for Interpreting Ambiguous Historical Pressure Data in the Wipp Gas-Generation Experiments.
The potential for generation of gases in transuranic (TRU) waste by microbial activity, chemical interactions, corrosion, and radiolysis was addressed in the Argonne National Laboratory-West (ANL-West) Gas-Generation Experiments (GGE). Data was collected over several years by simulating the conditions in the Waste Isolation Pilot Plant (WIPP) after the eventual intrusion of brine into the repository. Fourteen test containers with various actual TRU waste immersed in representative brine were inoculated with WIPP-relevant microbes, pressurized with inert gases, and kept in an inert-atmosphere environment for several years to provide estimates of the gas-generation rates that will be used in computer models for future WIPP Performance Assessments. Modest temperature variations occurred during the long-term ANL-West experiments. Although the experiment temperatures always remained well within the experiment specifications, the small temperature variation was observed to affect the test container pressure far more than had been anticipated. In fact, the pressure variations were so large, and seemingly erratic, that it was impossible to discern whether the data was even valid and whether the long-term pressure trend was increasing, decreasing, or constant. The result was that no useful estimates of gas-generation rates could be deduced from the pressure data. Several initial attempts were made to quantify the pressure fluctuations by relating these to the measured temperature variation, but none was successful. The work reported here carefully analyzed the pressure measurements to determine if these were valid or erroneous data. It was found that a thorough consideration of the physical phenomena that were occurring can, in conjunction with suitable gas laws, account quite accurately for the pressure changes that were observed. Failure of the earlier attempts to validate the data was traced to the omission of several phenomena, the most important being the variation in the headspace volume caused by thermal expansion and contraction within the brine and waste. A further effort was directed at recovering useful results from the voluminous archived pressure data. An analytic methodology to do this was developed. This methodology was applied to each archived pressure measurement to nullify temperature and other effects to yield an adjusted pressure, from which gas-generation rates could be calculated. A review of the adjusted-pressure data indicated that generated-gas concentrations among these containers after approximately 3.25 years of test operation ranged from zero to over 17,000 ppm by volume. Four test containers experienced significant gas generation. All test containers that showed evidence of significant gas generation contained carbon-steel in the waste, indicating that corrosion was the predominant source of gas generation
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Analysis of a water-coolant leak into a very high-temperature vitrification chamber.
A coolant-leakage incident occurred during non-radioactive operation of the Plasma Hearth Process waste-vitrification development system at Argonne National Laboratory when a stray electric arc ruptured az water-cooling jacket. Rapid evaporation of the coolant that entered the very high-temperature chamber pressurized the normally sub-atmospheric system above ambient pressure for over 13 minutes. Any positive pressurization, and particularly a lengthy one, is a safety concern since this can cause leakage of contaminants from the system. A model of the thermal phenomena that describe coolant/hot-material interactions was developed to better understand the characteristics of this type of incident. The model is described and results for a variety of hypothetical coolant-leak incidents are presented. It is shown that coolant leak rates above a certain threshold will cause coolant to accumulate in the chamber, and evaporation from this pool can maintain positive pressure in the system long after the leak has been stopped. Application of the model resulted in reasonably good agreement with the duration of the pressure measured during the incident. A closed-form analytic solution is shown to be applicable to the initial leak period in which the peak pressures are generated, and is presented and discussed
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A Survey of Mixed-Waste HEPA Filters in the DOE Complex
A brief investigation was made to determine the quantities of spent, mixed-waste HEPA filters within the DOE Complex. The quantities of both the mixed-waste filters that are currently being generated, as well as the legacy mixed-waste filters being stored and awaiting disposition were evaluated. Seven DOE sites representing over 89% of the recent HEPA filter usage were identified. These sites were then contacted to determine the number of these filters that were likely destined to become mixed waste and to survey the legacy-filter quantities. Inquiries into the disposition plans for the filters were also made. It was determined that the seven sites surveyed possess approximately 500 m3 of legacy mixed-waste HEPA filters that will require processing, with an annual generation rate of approximately 25 m3. No attempt was made to extrapolate the results of this survey to the entire DOE Complex. These results were simply considered to be the lower bound of the totality of mixed-waste HEPA filters throughout the Complex. The quantities determined encourage the development of new treatment technologies for these filters, and provide initial data on which an appropriate capacity for a treatment process may be based