Sterilization and reuse of masks for a standardized exhaled breath collection device by autoclaving.

Exhaled breath research has been hindered by a lack of standardization in collection and analysis methodologies. Recently, the Respiration Collector forIn VitroAnalysis (ReCIVA) sampling device has illustrated the potential to provide a consistent and convenient method for exhaled breath collection onto adsorbent media. However, the significant costs, compared to exhaled breath bags, associated with the standardized collector is believed to be the reason for limited widespread use by researchers in the exhaled breath field. For example, in addition to the sampling hardware, a single-use disposable silicon mask affixed with a filter is required for each exhaled breath collection. To reduce the financial burden, streamline device upkeep, reduce waste material, and ease the logistical burden associated with the single use masks, it is hypothesized that the consumable masks and filters could be sterilized by autoclaving for reuse. The masks were contaminated, autoclaved, and then tested for any surviving pathogens with spore strip standards and by measuring the optical density of cultures. The compound background collected when using the ReCIVA with new masks was compared to that collected with repeatedly autoclaved masks via thermal desorption gas chromatography mass spectrometry (TD-GC-MS). The capacity to block particulate matter of new filters was tested against that of autoclaved filters by introducing an aerosol and comparing pre-filter and post-filter particle counts. Finally, breath samplings were conducted with new masks and autoclaved masks to test for changes in measurements by TD-GC-MS of exogenous and endogenous compounds. The data illustrate the autoclave cycle sterilizes masks spiked with saliva to background levels (p= 0.2527). The results indicate that background levels of siloxane compounds are increased as masks are repetitively autoclaved. The data show that mask filters have significant breakthrough of 1µm particles after five repetitive autoclaving cycles compared to new filters (p= 0.0219). Finally, exhaled breath results utilizing a peppermint ingestion protocol indicate two compounds associated with peppermint, menthone and 1-Methyl-4-(1-methylethyl)-cyclohexanol, and an endogenous exhaled breath compound, isoprene, show no significant difference if sampled with a new mask or a mask autoclaved five times (p> 0.1063). Collectively, the data indicate that ReCIVA masks and filters can be sterilized via autoclave and reused. The results suggest ReCIVA mask and filter reuse should be limited to three times to limit potentially problematic background contaminants and filter dysfunction.

Comprehensive characterization of firing byproducts generated from small arms firing of lead-free frangible ammunition.

Following the introduction of lead-free frangible ammunition in United States Air Force small arms firing ranges, Combat Arms instructors have routinely reported experiencing adverse health symptoms during live fire training exercises, including sore throat, cough, and headache. Previous studies have found that these symptoms occur despite occupational exposure limits not being exceeded. To better characterize the potential source and mechanisms for health symptoms, a comprehensive characterization of the physicochemical properties of gases and aerosols emitted during the firing of the M9 pistol and M4 rifle using lead-free frangible ammunition was completed. Weapons were fired within a sealed chamber using a remote firing mechanism. A suite of direct-reading instruments and collection-based analytical methods were used to determine the composition of the emissions. Emissions were dominated by carbon monoxide and ultrafine particles. Other prevalent gases included carbon dioxide, ammonia, formaldehyde, hydrogen cyanide, and nitric oxide when measured using Fourier-transform infrared spectroscopy. An electrical, low-pressure impactor showed that, on average, the count median diameter immediately after firing was 36 ± 4 nm (n = 10 rounds) and 32 ± 3 nm (n = 14 rounds) for the M9 pistol and M4 rifle, respectively. Analytical methods were used to determine that emitted particles were primarily composed of soot, copper, and potassium, with trace amounts of calcium, silicon, sodium, sulfur, and zinc. Results from this research confirm prior work and expand upon the characterization of emissions generated from firing lead-free frangible ammunition. By employing multiple methods to measure and analyze data we were able to quantify both total and respirable particle fractions and determine particle morphology and composition. Characterization of the emissions provides insight into potential exposure risks that may lead to the development of adverse health symptoms allowing for the development of strategies for risk mitigation.

Video Exposure Monitoring and Position Tracking for Evaluating Particulate and Gas Exposures in a Fully Enclosed Small Arms Firing Range.

The exposure environment in small arms firing ranges is dynamic since ventilation conditions vary in space and time and instructors continuously move around throughout the range. Understanding the impact of engineering controls and instructor behavior on the levels of particulates and gases in the breathing zone is required for providing recommendations to mitigate exposure. In this study, video exposure monitoring (VEM) and position tracking technologies were used in conjunction with real-time measurements of ultrafine particle (UFP) and carbon monoxide (CO) exposures in the breathing zone of instructors in an enclosed small arms firing range. VEM was completed using Enhanced Video Analysis of Dust Exposure 2.1 developed by the National Institute for Occupational Safety and Health. With this program, video recordings of Combat Arms instructor activity were synced with exposure data collected in real-time during small arms training. Position tracking was completed using a system by Pozyx, which uses ultra-wideband (UWB) technology. Position tracking data was aligned with real-time sensor data via time-synchronization. VEM identified that the largest peaks in UFP and CO concentrations generally occurred when instructors were close to the firing line assisting shooters during live fire and when instructors were located near the center of the range near the back wall where the air supplies transition between the Left-Hand-Side (LHS) and Right-Hand-Side (RHS). The UWB position tracking results agreed with the VEM results, confirming that peak exposures occurred when firing range instructors were near the center of the range close to the back wall where the LHS and RHS air supplies transition. Without these exposure visualization technologies, this observation could not have been made. Thus, exposure visualization is a valuable tool to identify gaps in exposure assessment, although future technologies should focus on automation to expedite analysis.

Completion of the Set: Synthesis of the (6,X')-Flubromazepam Positional Isomers as Standards for Forensic Analysis.

Mounting concern among forensic examiners regarding the emergence of positional isomers as technically legal alternatives to scheduled benzodiazepines has encouraged the preemptive synthesis of analogues as standards. Recently, flubromazepam was identified by the Drug Enforcement Administration for future scheduling, and subsequently, 9 of the 12 possible flubromazepam isomers were synthesized. However, the three (6,X')-isomers proved inaccessible via that approach. Herein, through a redesigned synthetic approach, the remaining three isomers were obtained, thus completing the set and enabling future forensic analysis.

Calcium-Catalyzed Formal [5 + 2] Cycloadditions of Alkylidene ß-Ketoesters with Olefins: Chemodivergent Synthesis of Highly Functionalized Cyclohepta[b]indole Derivatives.

The calcium-catalyzed, formal [5 + 2] cycloaddition of indolyl alkylidene ß-ketoesters with mono- and disubstituted aryl olefins to form cyclohepta[b]indole derivatives has been established. Unanticipated chemodivergence with phenyl vinyl sulfide/ether revealed a double [5 + 2] cycloaddition cascade providing ethano-bridged cyclohepta[b]indoles. Overall, the method's highlights include: (1) use of a green, calcium-based catalyst (2.5 mol % loading); (2) reaction times under 1 h; (3) mild reaction conditions; (4) substrate-derived chemodivergence; (5) functional group tolerance; and (6) examples of derivatization.