Design and research of 2D piston pumps with a stacked cone roller set

A new type of two-dimensional (2D) piston pump with a stacked cone roller set was introduced to eliminate the influence of the gap between the guiding rail and the cone roller. First, the structure and working principle of the 2D piston pump were studied; then, a corresponding mathematical model which considered the oil viscosity and oil churning loss caused by the rotation of the guiding rail in the enclosed chamber was established to examine the volumetric and mechanical efficiency of the 2D piston pump. The effects of different speeds, load pressures, and rolling friction coefficients between the guiding rail and the cone rollers on the efficiency were considered. During the test, when the speed was 6000 r/min and the load pressure was 6 MPa and 8 MPa, the volumetric efficiency reached 98.3% and 96.8%, respectively, basically consistent with the theoretical analysis. Because the temperature rise of the tested pump caused the oil viscosity and the eccentricity of the piston and piston rings increased the leakage, the test result was slightly lower than that of the theoretical analysis. When the speed was 1000 r/min and the load pressure was 5 MPa, the mechanical efficiency was 69.3%, and the mechanical efficiency model was consistent with the test results. However, with the increase in speed and load pressure, the difference between the test results and theoretical analysis results increased because the supporting force of the cone roller on the guiding rail increased, increasing the rolling frictional losses.

Removal of Volatile Organic Compounds by Means of a Felt-Based Living Wall Using Different Plant Species

Poor indoor quality affects people’s health and well-being. Phytoremediation is one way in which this problem can be tackled, with living walls being a viable option for places with limited space. The aim of this study was to evaluate the efficiency of five plant species in a living wall to remove Volatile Organic Compounds (VOCs) and to identify whether the type of pollutant has any influence. An enclosed chamber was used to add the contaminants n-hexane and formaldehyde independently. Total VOCs were measured for three days in two scenarios: (1) empty chamber, and (2) chamber with living wall. Five living walls were prepared, each with three plants of the same species: Spathiphyllum wallisii, Philodendron hederaceum, Ficus pumila, Tradescantia pallida, and Chlorophytum comosum. There was no correlation between leaf area/fresh weight/dry weight and the contaminant reduction. In general, all five species were more efficient in reducing TVOCs when exposed to formaldehyde than to n-hexane. Chlorophytum comosum was the most efficient species in reducing the concentration of TVOCs for both contaminants, Spathiphyllum wallisii being the least efficient by far.

Axonopathy precedes cell death in ocular damage mediated by blast exposure

Traumatic brain injuries (TBI) of varied types are common across all populations and can cause visual problems. For military personnel in combat settings, injuries from blast exposures (bTBI) are prevalent and arise from a myriad of different situations. To model these diverse conditions, we are one of several groups modeling bTBI using mice in varying ways. Here, we report a refined analysis of retinal ganglion cell (RGC) damage in male C57BL/6J mice exposed to a blast-wave in an enclosed chamber. Ganglion cell layer thickness, RGC density (BRN3A and RBPMS immunoreactivity), cellular density of ganglion cell layer (hematoxylin and eosin staining), and axon numbers (paraphenylenediamine staining) were quantified at timepoints ranging from 1 to 17-weeks. RNA sequencing was performed at 1-week and 5-weeks post-injury. Earliest indices of damage, evident by 1-week post-injury, are a loss of RGC marker expression, damage to RGC axons, and increase in glial markers expression. Blast exposure caused a loss of RGC somas and axons—with greatest loss occurring by 5-weeks post-injury. While indices of glial involvement are prominent early, they quickly subside as RGCs are lost. The finding that axonopathy precedes soma loss resembles pathology observed in mouse models of glaucoma, suggesting similar mechanisms.

Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

Heat Stress Reduces Metabolic Rate While Increasing Respiratory Exchange Ratio in Growing Pigs

Heat stress (HS) diminishes animal production, reducing muscle growth and increasing adiposity, especially in swine. Excess heat creates a metabolic phenotype with limited lipid oxidation that relies on aerobic and anaerobic glycolysis as a predominant means of energy production, potentially reducing metabolic rate. To evaluate the effects of HS on substrate utilization and energy expenditure, crossbred barrows (15.2 ± 2.4 kg) were acclimatized for 5 days (22 °C), then treated with 5 days of TN (thermal neutral, 22 °C, n = 8) or HS (35 °C, n = 8). Pigs were fed ad libitum and monitored for respiratory rate (RR) and rectal temperature. Daily energy expenditure (DEE) and respiratory exchange ratio (RER, CO2:O2) were evaluated fasted in an enclosed chamber through indirect calorimetry. Muscle biopsies were obtained from the longissimus dorsi pre/post. HS increased temperature (39.2 ± 0.1 vs. 39.6 ± 0.1 °C, p < 0.01) and RER (0.91 ± 0.02 vs. 1.02 ± 0.02 VCO2:VO2, p < 0.01), but decreased DEE/BW (68.8 ± 1.7 vs. 49.7 ± 4.8 kcal/day/kg, p < 0.01) relative to TN. Weight gain (p = 0.80) and feed intake (p = 0.84) did not differ between HS and TN groups. HS decreased muscle metabolic flexibility (~33%, p = 0.01), but increased leucine oxidation (~35%, p = 0.02) compared to baseline values. These data demonstrate that HS disrupts substrate regulation and energy expenditure in growing pigs.

The Millipede-Predation Behavior of Promecognathus and Exceptional Cyanide Tolerance in Promecognathus and Metrius (Coleoptera: Carabidae)

Promecognathus (Carabidae) includes beetles that are specialist predators whose prey are polydesmidan millipedes that produce highly toxic hydrogen cyanide and benzaldehyde as a defense, and it is unknown how Promecognathus overcomes these chemicals. We observed Promecognathus laevissimus (Dejean, 1829) and P. crassus (LeConte, 1868) in the laboratory and found that they did not use behaviors to avoid the chemical defenses of their prey, Xystocheir dissecta (Wood, 1867) (Polydesmida: Xystodesmidae). We tested benzaldehyde as a feeding deterrent and found noticeable deterrence in all carabid beetles tested except Promecognathus species and Metrius contractus (Eschscholtz, 1829). A total of 18 carabid species were exposed to cyanide vapors in an enclosed chamber for 10 min to determine their relative tolerances. Promecognathus and M. contractus were unaffected by HCN exposures 7–15 times greater than quantities that knocked down all other species. Promecognathus laevissimus and M. contractus were then exposed to high levels of HCN for 2 h, and while individuals of M. contractus succumbed, all P. laevissimus were still moving after 2 h. It is possible that Promecognathus evolved a high tolerance to cyanide as part of a suite of adaptations related to millipede predation. However, we have no plausible explanation for the high tolerance in Metrius, for which there is no evidence of millipede feeding. This is the first documented case of predatory insects that exhibit high tolerance and potential resistance to cyanide. Possibly, these beetles have a detoxification mechanism that is not cyanide specific, as their tolerance level far exceeds any dose they would encounter in their natural habitat.

Drought-induced reduction in methane fluxes and its hydrothermal sensitivity in alpine peatland

Accurate estimation of CH4 fluxes in alpine peatland of the Qinghai-Tibetan Plateau under extreme drought is vital for understanding the global carbon cycle and predicting future climate change. However, studies on the impacts of extreme drought on peatland CH4 fluxes are limited. To study the effects of extreme drought on CH4 fluxes of the Zoige alpine peatland ecosystem, the CH4 fluxes during both extreme drought treatment (D) and control treatment (CK) were monitored using a static enclosed chamber in a control platform of extreme drought. The results showed that extreme drought significantly decreased CH4 fluxes in the Zoige alpine peatland by 31.54% (P < 0.05). Extreme drought significantly reduced the soil water content (SWC) (P < 0.05), but had no significant effect on soil temperature (Ts). Under extreme drought and control treatments, there was a significant negative correlation between CH4 fluxes and environmental factors (Ts and SWC), except Ts, at a depth of 5cm (P < 0.05). Extreme drought reduced the correlation between CH4 fluxes and environmental factors and significantly weakened the sensitivity of CH4 fluxes to SWC (P < 0.01). Moreover, it was found that the correlation between subsoil (20 cm) environmental factors and CH4 fluxes was higher than with the topsoil (5, 10 cm) environmental factors under the control and extreme drought treatments. These results provide a better understanding of the extreme drought effects on CH4 fluxes of alpine peatland, and their hydrothermal impact factors, which provides a reliable reference for peatland protection and management.

Correlation between formaldehyde emission characteristics in enclosed desiccators with five different geometries

The static headspace method using a small enclosed chamber has been extensively used to estimate the emission characteristics of formaldehyde, e.g., emission rates from building materials. The formation of the transient formaldehyde concentration by emission, diffusion and sorption in a small confined chamber was investigated using three-dimensional modelling and numerical analyses. Here, five types of glass desiccators were adopted as the small chamber for the headspace method. The inner geometries of the desiccator with the emission source (the building material) and sorbent (water in a Petri dish) were precisely modelled. Transient numerical analyses were performed to determine the formaldehyde emission from different building materials of the external (evaporative) diffusion control type, molecular diffusion and sorption on the water in the confined desiccators. In order to clarify the effect of the desiccator inner geometry on the formaldehyde emission characteristics, the equivalent diffusion length ( Ld) concept, which could be identified as the representative one-dimensional diffusion length scale, was proposed. The results of the numerical analyses showed that Ld and the formaldehyde concentration in the sorbent solution over a 24 h numerical experiment were significantly affected by the desiccator geometry. These results confirmed that the calibration of the emission rate with external diffusion control using Ld is appropriate when measuring the formaldehyde emission rate in an enclosed desiccator with different geometries.