Seaside Petunia Susceptibility to Herbicides Used in Dry Bulb Onion

Seaside petunia (Calibrachoa parviflora) is a mat-forming plant species that was recently reported in fall-seeded onion (Allium cepa) in the southwestern United States. To initiate development of herbicide recommendations for seaside petunia in onion, we conducted a study to determine seaside petunia susceptibility to commonly used herbicides for broadleaf weed control after onion emergence. Our study included herbicides applied at below-label rates, which provided insights on seaside petunia responses to reductions in the amount of herbicide available for plant absorption. For herbicides with preemergence activity, our growth chamber study indicated that soil applications of flumioxazin or oxyfluorfen (0.06 and 0.25 lb/acre, respectively) prevented seaside petunia seedling emergence when applied at 0.125×, 0.25×, 0.5×, and 1.0× the labeled rates for onion. Labeled rate treatments of dimethenamid-P (0.84 lb/acre) and S-metolachlor (0.64 lb/acre) inhibited seedling emergence similar to labeled rate treatments of flumioxazin and oxyfluorfen; however, below-label rate treatments of dimethenamid-P and S-metolachlor resulted in diminished control of seaside petunia compared with the labeled rate treatments. Following labeled rate applications of dimethyl tetrachloroterephthalate [DCPA (6 lb/acre)] and pendimethalin (0.71 lb/acre), more than 50% of seaside petunia seedlings emerged compared with the nontreated control. For herbicides with postemergence activity on weeds, our greenhouse study indicated that bromoxynil at 0.37 lb/acre, flumioxazin at 0.06 lb/acre, and oxyfluorfen at 0.25 lb/acre equally reduced growth of seaside petunia plants that were small at the time of spraying (stem length, 1–2 cm). Postemergence control of seaside petunia with oxyfluorfen and flumioxazin decreased as plant size at spraying increased; however, bromoxynil effects on seaside petunia remained high as stem length at spraying increased from 5 to 12 cm. Based on the results of this study, we conclude that promising herbicide programs for seaside petunia in onion include oxyfluorfen or flumioxazin for preemergence control and bromoxynil for postemergence control. These herbicides, alone and in combination, should be evaluated for seaside petunia control and onion phytotoxicity in future field trials.

Correlation of Respiratory Aerosols with Metabolic Carbon Dioxide

Respiratory Aerosols from breathing and talking have found wide acceptance as a transmission route for viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies have found particles with diameters ranging from 10 nm to 145 µm, exhibited from different regions in the respiratory system. We present the first chamber study, in which respiratory aerosols have been simultaneously measured with carbon dioxide (CO2) to establish the correlation between the two concentrations. CO2 concentrations are easily available through low-cost sensors and could be used to estimate viral exposure through this correlation, whereas source-specific aerosol measurements are complicated and not possible with low cost sensors. The increase in both PM10 and CO2 was linear over ten minutes in a 2 m3 chamber for all participants, suggesting a strong correlation. On average, talking released more particles than breathing, with 14,600 ± 16,800 min-1 (one-σ standard deviation) and 6,210 ± 5,630 min-1 on average, respectively, while CO2 increased with 139 ± 33 ppm min-1 during talking and 143 ± 29 ppm min-1 during breathing. Assuming a typical viral load of 7 × 106 RNA copies per ml of oral fluid, ten minutes of talking and breathing are estimated to produce 7 and 16 suspended RNA copies, respectively, correlating to a CO2 concentration of around 1.800 ppm in a 2 m3 chamber. This provides a strong argument for keeping indoor spaces well ventilated and shows how CO2 concentrations, measured with low-cost sensors, could be used as a proxy for viral exposure.

Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

A rotating detonation rocket engine (RDRE) with various convergent nozzles and chamber lengths is investigated. Three hundred hot-fire tests are performed using methane and oxygen ranging from equivalence ratio equaling 0.5–2.5 and total propellant flow up to 0.680 kg/s. For the full-length (76.2 mm) chamber study, three nozzles at contraction ratios ϵc = 1.23, 1.62 and 2.40 are tested. Detonation is exhibited for each geometry at equivalent conditions, with only fuel-rich operability slightly increased for the ϵc = 1.62 and 2.40 nozzles. Despite this, counter-propagation, i.e., opposing wave sets, becomes prevalent with increasing constriction. This is accompanied by higher number of waves, lower wave speed Uwv and higher unsteadiness. Therefore, the most constricted nozzle always has the lowest Uwv. In contrast, engine performance increases with constriction, where thrust and specific impulse linearly increase with ϵc for equivalent conditions, with a 27% maximum increase. Additionally, two half-length (38.1 mm) chambers are studied including a straight chamber and ϵc = 2.40 nozzle; these shortened geometries show equal performance to their longer equivalent. Furthermore, the existence of counter-propagation is minimized. Accompanying high-fidelity simulations and injection recovery analyses describe underlying injection physics driving chamber wave dynamics, suggesting the physical throat/injector interaction influences counter-propagation.

Shedding light on tropospheric H2SO4 production from Criegee intermediates + SO2: a comprehensive laboratory chamber study using the highly instrumented HELIOS platform

<p>Although the dominant source of H<sub>2</sub>SO<sub>4</sub> in the atmosphere is generally considered to be the reaction of SO<sub>2</sub> with OH, it is probable that the rapid reactions of Criegee intermediates (CIs) with SO<sub>2</sub> can contribute significantly to the tropospheric H<sub>2</sub>SO<sub>4</sub> budget under certain conditions. CIs are produced from alkene ozonolysis, and the vast quantities of unsaturated biogenic and anthropogenic volatile organic compounds emitted could provide a large and diverse flux of CIs to the atmosphere. There remain several key uncertainties regarding the global importance of CIs towards SO<sub>2</sub> oxidation, which are principally related to the ambient concentrations of CIs and the competition between CI reaction with SO<sub>2</sub> against the many other bimolecular and unimolecular loss processes. This is especially true of the larger, more complex CIs that are produced from terpene ozonolysis.</p><p>We present experimental studies of the ozonolysis of tetramethylethylene, α-pinene and limonene, using the HELIOS chamber. HELIOS is a highly instrumented large-scale outdoor atmospheric simulation chamber and consists of a hemispheric 90 m<sup>3</sup> Teflon-foil reactor, which is interfaced to a variety of on-line measurements including FTIR, PTR-ToF-MS, FIGAERO-ToF-CIMS, OH/H<sub>2</sub>SO<sub>4</sub>-CIMS, Aerolaser HCHO, LOPAP and SMPS, together with several GC-MS/FID and LC-MS instruments and a suite of monitors (NO, NO<sub>2</sub>, O<sub>3</sub>). Equipped with this range of instrumentation we are able to conduct alkene ozonolysis under near-ambient conditions, whilst we also have a high coverage of key reactive species in the systems of interest.</p><p>From our results, we are able to provide new information regarding kinetic and mechanistic behaviour of several atmospherically important CIs and their reactive intermediates, providing new constraints on the role of CIs on the tropospheric H<sub>2</sub>SO<sub>4</sub> budget.</p><p><strong>Keywords:</strong> ozonolysis, Criegee Intermediate, sulfur dioxide, sulfuric acid, kinetics</p>

Spatial arrangement of pre-war housing estates in the context of sustainable development goals on the example of the Księże Małe housing estate in Wrocław

The article aims to present the assumptions and a part of the chamber study results conducted on the Księże Małe estate in Wrocław. The starting point for the research was the observation that the pre-war German housing estates were planned in a functional way, with great care for the surroundings of the buildings, as well as with the use of solutions that would now be defined as elements of blue or green infrastructure. Thus, the pre-war spatial arrangement manner is in line with the contemporary postulates of sustainable development and "healthy" cities. However, the functions of green areas and their elements have degraded over time and nowadays it is often possible to read the former planning concept only by means of comparative cartographic studies. The results of the preliminary research confirm that the subsequent housing development transformations were of a degrading nature, and the pre-war character of the building surroundings is illegible for residents and readable in archival materials that have not been elaborated so far. Recalling the memory of the former arrangement method may contribute to project activities in the area of urban adaptation to climate change, and past practices, a model for shaping contemporary urban plans.