Critical correlations in an ultracold Bose gas revealed by means of a temporal Talbot-Lau interferometer

We study experimentally the critical correlation in an ultra-cold Bose gas with a temporal Talbot-Lau (TL) interferometer. Near the critical temperature, we observe a bi-modal density distribution in an ultra-cold Bose gas after the application of the TL interferometer. The measured fraction of the narrower peak in the density distribution displays a clear peak within the critical regime. The peak position agrees with the critical temperature calculated with the finite-size and interaction corrections. The critical exponents are extracted from the peak and they agree with the critical exponents for the correlation length.Comment: 5 pages, 3 figures and supplemental materia

The observation of diffraction phases in matter wave scattering

We study the diffraction phase of different orders via the Dyson expansion series, for ultracold atomic gases scattered by a standing-wave pulse. As these diffraction phases are not observable in a single pulse scattering process, a temporal Talbot-Lau interferometer consisting of two standing-wave pulses is demonstrated experimentally with a Bose-Einstein condensate to explore this physical effect. The role of the diffraction phases is clearly shown by the second standing-wave pulse in the relative population of different momentum states. Our experiments demonstrate obvious effects beyond the Raman-Nath method, while agree well with our theory by including the diffraction phases. In particular, the observed asymmetry in the dependence of the relative population on the interval between two standing-wave pulses reflects the diffraction phase differences. The role of interatomic interaction in the Talbot-Lau interferometer is also discussed.Comment: 7 pages, 3 figures, accepted by Phys. Rev.

Comparison of Air Emissions from Raw Liquid Pig Manure and Biogas Digester Effluent Storages

Biogas digesters are commonly used in livestock farming in China. The digestion process converts large amounts of raw liquid manure (RLM) to biogas digester effluent (BDE). The BDE is then stored on the farm for some time before land application as crop or orchard nutrients. Storage of RLM or BDE is associated with gas emissions, although little information is available concerning comparison of air emissions between the two handling practices. This study was conducted to compare methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) emissions from RLM and BDE storages using dynamic emission vessels (DEVs). Both media were stored in closed vessels (50 L) at a 40 cm storage depth, a constant storage temperature of 30°C, and a headspace air exchange rate of 15 to 17 air changes per hour (ACH) for 22 days. The results showed that the average daily gas emission rates for RLM and BDE, in mg L-1 d-1, were, respectively, 102.9 and 125.3 CO2 (p \u3c 0.05), 0.72 and 3.33 N2O (p \u3c 0.05), 29.2 and 0.32 CH4 (p \u3c 0.05), and 1.21 and 0.66 NH3 (p = 0.08). The total greenhouse gas (GHG = CH4 + CO2 + N2O) emissions were similar for RLM and BDE, 1.05 and 1.12 g CO2-eq L-1 d-1, respectively (p = 0.26). Nitrous oxide (N2O) emissions accounted for 88.2% of the CO2-eq GHG emissions for BDE, whereas CH4 emissions accounted for 69.7% of the CO2-eq GHG emissions for RLM. The high N2O emissions from BDE likely resulted from the lower COD/N ratio in BDE than RLM under the storage conditions. Differences in gaseous emission characteristics between RLM and BDE were attributed to the differences in methanogen species and the population of ammonia-oxidizing bacteria (AOB)

Comparative Evaluation of Cooling Systems for Farrowing Sows

The field studies reported here compare the performance of three cooling systems for relieving farrowing/lactating sows of heat stress under the warm and humid production climate in southern China. The comparative systems included (1) tunnel ventilation (TV) with vertical head-zone ventilation (HZV) vs. TV with HZV and drip cooling (DC), (2) TV only vs. TV with DC, and (3) horizontal air mixing (HAM) only vs. HAM and DC. For the HZV, a perforated overhead air duct was used to create an air velocity of 0.6 to 0.8 m/s (118 to 157 ft/min) in the head zone of the sow. The paired tests were conducted successively in an experimental commercial farrowing barn housing 42 sows. Body temperature (Tb) and respiration rate (RR) of the sows were used to evaluate the efficacy of the systems. The results indicate that sows under TV + DC or TV + HZV + DC had significantly lower Tb than those under TV only or TV + HZV (P \u3c 0.01 and P \u3c 0.001, respectively). DC under HAM was less effective for Tb reduction (P \u3e 0.05). DC reduced RR in all cases, 42% under TV (P \u3c 0.01), 41% under TV + HZV (P \u3c 0.01), and 22% under HAM (P \u3e 0.05). It was concluded that TV with DC provides the most cost-effective cooling scheme

Temporal Variation of Greenhouse Gas Emission in Gestation Swine Building

The objective of this study was to examine the temporal variation of greenhouse gas (GHG) concentration in the swine building over both daily and seasonal basis. The air samples were collected every one hour continuously for three days during summer and spring, and analyzed by gas chromatography (GC). Barn temperature was collected and the management practices were also noted. Results showed that methane (CH4) and carbon dioxide (CO2) concentration was related to the internal temperature and ventilation. Daily CH4 and CO2 concentrations varied more during cold weather than warmer weather; nighttime GHG concentration in the gestation building was higher than daytime because of the low air exchange. Average CH4 concentration in the gestation building was 16.67 + 9.88 ppm in spring and 9.25 + 7.64 ppm in summer. Average CO2 concentrations were 2361.65 + 960.96 ppm in spring and 1134.96 + 373.53 ppm in summer

Ammonia and Greenhouse Gas Emissions from Biogas Digester Effluent Stored at Different Depths

Carbonaceous and nitrogenous gases are produced during storage of livestock manure, with the magnitude of production being affected by the chemical properties of the manure and the physical conditions of storage. This lab-scale study quantifies the emission rates of ammonia (NH3), nitric oxide (NO), and greenhouse gases (GHG), i.e., methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), from biogas digester effluent (BDE) stored at different depths of 1.0, 1.5, and 2.0 m in dynamic emission vessels (DEVs). The selected storage depths were reflective of the typical depth range of on-farm BDE storage in China. The static storage was held at a relatively constant media temperature of 15°C and an air exchange rate of 11.5 air changes per hour (ACH) for 78 days. Each depth regimen was replicated four times using four DEVs (12 DEVs total). The results showed that the mean (±SE) daily gaseous emission rates per volume of BDE stored at 1.0, 1.5, and 2.0 m depths, in g gas m-3 d-1, were, respectively, 9.1 (±0.7), 10.1 (±0.6), and 10.1 (±0.4) for CH4 (p = 0.39); 38.0 (±2.2), 34.5 (±1.3), and 30.7 (±0.6) for CO2 (p \u3c 0.05); 1.9 (±0.11), 1.3 (±0.08), and 0.9 (±0.03) for NH3 (p \u3c 0.05); and 6.7 (±0.5) × 10-3, 5.0 (±0.8) × 10-3, and 3.4 (±0.2) × 10-3 for N2O (p \u3c 0.05). Nitric oxide (NO) emissions were negligible. The overall GHG (CH4 + N2O + CO2) emissions were dominated by CH4, which accounted for more than 85% of the CO2-equivalent emissions for all three storage depths. The CH4 emissions peaked during the early storage period, with the first 20-day cumulative emissions accounting for 56% to 58% of the total 78-day storage emissions. The results reveal that storage of BDE at 2.0 m depth yielded lower CO2, NH3, and N2O emission rates but similar CH4 emission rates compared to the 1.0 and 1.5 m depths

Carbon Footprint Assessment of Large-scale Pig Production System in Northern China: a Case Study

China raises 50% of the global live pigs. However, few studies on carbon footprint (CF) of large-scale pig production based on China’s actual production conditions have been carried out. In this study, life cycle assessment (LCA) method and actual production data of a typical large-scale pig farm in Northern China were used to assess greenhouse gas (GHG) emissions or CF associated with the whole process of pig production, including feed production (crop planting, feed processing, and transportation), enteric fermentation, manure management and energy consumption. The results showed a CF of 3.39 kg CO2-eq per kg of live market pig, and relative contributions of 55%, 28%, 13%, and 4% to the total CF by feed production, manure management, farm energy consumption, and enteric fermentation, respectively. Crop planting accounted for 66% of the feed production CF, while feed processing and transportation accounted for the remaining 34%. Long-distance transport of semi-raw feed materials caused by planting-feeding separation and over-fertilization in feed crop planting were two main reasons for the largest contribution of GHG emissions from feed production for the total CF. CF from nitrogen fertilizer application accounted for 33%-44% of crop planting, and contributed to 16% of the total CF. CF from transportation of feed ingredients accounted for 17% of the total CF. If the amount of nitrogen fertilizer used for producing the main feed ingredients is reduced from 209 kg/hm2 (for corn) and 216 kg/hm2 (for wheat) to 140 kg/hm2 (corn) and 180 kg/hm2 (wheat), respectively, the total CF would be reduced by 7%. If transportation distance for feed materials decreased from 325-493 km to 30 km, along with reducing the number of empty vehicles for the transport, total CF would be reduced by 18%. The combined CF mitigation potential for over-fertilization and transportation distance is 26%. In addition, use of pit storage – anaerobic digestion – lagoon practice can reduce GHG emissions from manure management by 76% as compared to the traditional pit storage – lagoon manure treatment method. This case study reveals the impact of planting-feeding separation and over-fertilization on CF of pig supply chain in China. Manure management practice of pit storage – anaerobic digestion – lagoon is much more conductive to reducing CF as compared to the traditional method of pit storage – lagoon