High-value recycling of food waste (FW) can be accomplished through the production of lactic acid (LA). In this work, LA was produced via electro-fermentation (EF) on FW as a single substrate in non-sterile, non-inoculated environment. Electric stimulation (ES) coupled with granular activated carbon (GAC) was used to increase LA production. The findings demonstrated that the addition of 10 g/L of GAC to the system at a voltage of -1 V for 144 h of fermentation resulted in an increase in the LA concentration and maximum production rate of 33.6% and 12.2%, respectively, when compared to the Blank group. The experimental group coupled with ES and GAC also exhibited the highest intracellular NADH/NAD+ ratio, a notable increase in the abundance of Actinobacteriota and Proteobacteria, and prominent redox peaks. In terms of the synergistic regulatory effect of key enzymes, the activity of α -glucosidase was enhanced. Besides, the abundance of related enzymes such as lactate dehydrogenase increased, significantly strengthening the glycolytic pathway for LA production and inhibiting the heterolactic fermentation process. The results of this study provide an effective way to recycle FW and provide theoretical support for the analysis of the synergistic mechanism of electron transfer and metabolic regulation in the EF system.

This study presents the development and experimental characterization of a single-stage 3He sorption cooler. Operating on the principle of pressure reduction evaporation with activated carbon as the adsorbent, the system achieves stable sub-Kelvin cooling without moving parts. Key components include a sorption pump featuring optimized heat transfer fins, a three-stage pump tube designed to balance flow conductance with thermal isolation, and an evaporator incorporating internal fins to minimize Kapitza resistance. Theoretical analyses of condensation efficiency, self-cooling loss, and thermodynamic cycles were conducted, predicting high liquefaction rates at low condensation temperatures. The experimental apparatus integrates a two-stage GM cryocooler for precooling, a 1.2 K 4He bath for condensation, and a gas recycling system to manage the 3He inventory. Experimental results demonstrate a no-load minimum temperature of 287 mK and a cooling capacity of 2.5 & micro;W at 300 mK, exhibiting a quasi-linear relationship between temperature and cooling power in the low power regime.

Abstract Sub-Kelvin technology plays a crucial role in both ground-based experiments and space exploration. 3 He sorption cooling is one of the few methods capable of achieving temperatures below 500 mK. The sorption cooler is based on the principle of liquid helium evaporation refrigeration, and the adsorption and desorption of helium gas are realized by periodically cooling and heating activated carbon. Due to its advantages, including compact size, light weight, absence of vibration and electromagnetic interference, and simple operation, it offers strong competitiveness in the field of space extreme low temperature refrigeration. In this paper, we present the design and performance evaluation of a closed-cycle single-shot 3 He sorption cooler, which incorporates a sorption pump filled with activated carbon granules. The 3 He sorption cooler, pre-cooled by a two-stage GM type pulse tube refrigerator and a superfluid helium bath, achieves a minimum temperature of 393.6 mK and provides a net cooling power of 200 µW at 486 mK. At a charge of 2 STP L 3 He, a single cycle can be maintained at temperatures below 400 mK for about 6 hours. The 3 He sorption cooler needs further optimization and is expected to be used for pre-cooling of the adiabatic demagnetization refrigerator in the future.

Lignocellulosic hydrolysate is rich in various fermentable sugars, such as glucose, xylose, and cellobiose. Utilizing these sugars for L-lactic acid fermentation represents a promising strategy for the high-value utilization of biomass. However, when mixed sugars serve as carbon sources, microorganisms typically undergo carbon catabolite repression (CCR) at the initial fermentation stage, which significantly compromises both the yield and productivity of L-lactic acid. To clarify CCR mechanisms and explore effective mitigation strategies, Bacillus coagulans DSM 2314 was used as the fermentative strain, the effects of pH and temperature on fermentation with single and mixed carbon sources were examined, and L-lactic acid yields, productivities, and key enzymatic activities across different fermentation systems were systematically compared. The results showed that in glucose-containing mixed-sugar systems, glucose imposed strong CCR effects on both cellobiose and xylose. Under optimal conditions (initial total sugar concentration of 50 g/L, pH 7.0, and 45 °C), L-lactic acid yields increased in the following order: glucose/xylose (15.58 g/L) < glucose/cellobiose (29.65 g/L) < glucose (31.87 g/L). In contrast, in the glucose-free cellobiose/xylose system, both sugars were nearly co-consumed by B. coagulans DSM 2314, and L-lactic acid production was not significantly diminished by the mixing of carbon sources (xylose (27.45 g/L) < cellobiose/xylose (28.64 g/L) < cellobiose (29.60 g/L)). Under replicated optimal condition experiments, analyses of sugar consumption rates and enzyme activities further confirmed that the CCR between cellobiose and xylose was significantly weaker than in other mixed-sugar systems, with the L-lactic acid yield in the cellobiose/xylose system 1.61-fold higher than in the glucose/xylose system. These findings demonstrate that substituting glucose with cellobiose in mixed-sugar fermentation is an effective approach to mitigating CCR, providing a theoretical basis for efficient L-lactic acid production from lignocellulosic hydrolysates.

Abstract A 4K hybrid JT cooler is developed to precool the adiabatic demagnetization refrigerator (ADR) for the Hot Universe Baryon Surveyor (HUBS) mission, which is proposed to study “missing” baryons in the universe. The 4K hybrid JT cooler is composed of a 4He JT cooler precooled by a two-stage thermally coupled pulse tube cooler. Recently, the two-stage pulse tube cooler is optimized to provide more precooling power for the JT loop. The performance of the hybrid JT cooler has been improved and special efforts have been made to optimize the compression system of the JT loop. Eventually, cooling power of 100mW is achieved at 4K which is able to meet the requirements of the ADR of HUBS.

Semi-continuous experiments were carried out to investigate the effects of lactic acid (LA) fermentation on the biomethanation of food waste (FW) in two-stage anaerobic digestion (TSAD). The results showed that the LA fermentation in the acidogenic reactor (AR) improved the performance of FW's TSAD by increasing biomethane production and organic matter removal by 17.02 +/- 4.64 % and 4.84 +/- 1.50 % respectively and by upgrading the biogas quality. LA fermentation increased the substrate utilization rate, reduced the loss of chemical oxygen demand, and decreased the invalid conversion of organic matter in TSAD. LA fermentation also increased the relative abundance of Methanosarcina from 13.57 % to 55.68 % and decreased that of Methanosaeta from 30.22 % to 19.87 % in the methanogenic reactor (MR), which reduced the partial hydrogen pressure and promoted the conversion of LA to acetic acid rather than propionic acid. Furthermore, LA fermentation increased the abundance of functional enzymes related to the major methanogenesis pathways in the MR.

Sub-Kelvin technologies are essential for applications such as space detection, quantum computing, and condensed-matter physics. Among traditional sub-Kelvin technologies, including sorption cooling, adiabatic demagnetization refrigeration, and dilution refrigeration, sorption cooling shows unique competitiveness in space environments for its vibration-free operation, compactness, and absence of electromagnetic interference. Based on the principle of pressure reduction evaporation cooling, He-3 sorption coolers achieve temperatures around 300 mK, surpassing He-4 sorption coolers (similar to 800 mK) due to higher vapour pressures and the absence of superfluid constraints. He-3 sorption systems, initially developed in the 1960s, remain crucial for missions requiring reliability and simplicity. Advancements include modular and multi-stage designs, extending operating temperatures to 250 mK. Continuous systems using two sorption pumps mitigate intermittency, enabling stable cooling for weeks. Space applications face micro-gravity challenges, which are addressed by using porous matrices that leverage capillary forces to confine liquid He-3. Successful implementations include the Herschel satellite, which achieved 290 mK with 10 mu W cooling power. Hybrid coolers, which integrate sorption coolers with ADR or DR, achieve ultra-low temperatures (similar to 50 mK), essential for missions like SPICA and ATHENA. Current research is focused on gravity-independent designs, mechanical precooling to eliminate liquid helium dependency, and enhancing cryochains from 300 K to 50 mK. This paper reviews He-3 sorption cooler principles, technological evolution from cryostats to modular systems, space adaptations, and hybrid architectures. Key challenges related to non-equilibrium adsorption and micro-gravity fluid dynamics are discussed.

To investigate the effects of aeration pretreatment on the anaerobic digestion (AD) of swine manure, five pretreatment groups were established with dissolved oxygen (DO) in each group set to 0.0, 0.4, 0.8, 1.4, and 2.0 mg/L, respectively. The results demonstrated that compared to the non-aeration group, methane production increased to varying degrees with different aeration pretreatments (AP), with a maximum increase of 27.98% (DO = 2.0 mg/L). AP reduced the hydrogen sulfide (H2S) content of biogas. The H2S concentration in the DO = 2.0 mg/L was only 0.209%, and this represented an increased H2S removal rate of 49.27% compared to that of the DO = 0.0 mg/L (0.412%). Simultaneously, AP increases the hydrolysis rate. When the DO concentration reached 2.0 mg/L, the hydrolysis rate reached its maximum. An increase in the hydrolysis rate further enhanced the removal rate of organic matter. The organic matter removal rate was highest (36.96%) at DO = 2.0 mg/L. AP effectively prolonged the methane generation time and shortened the lag time of methane generation. AP creates a brief micro aerobic environment, accelerates substrate hydrolysis, and promotes the production and consumption of total volatile fatty acids, particularly acetic acid. Additionally, AP promoted the symbiotic relationship between Caldicoprobacter (20.93%-34.96%) and Metanosaeta (14.73%-18.45%). [GRAPHICS] .

Joule-Thomson (JT) cryocoolers play an essential role in space exploration missions. The JT cryocoolers with different working fluids have different operating temperatures. 4He and 3He are used in JT coolers to obtain temperatures below 4 K. Due to the different physical properties of 4He and 3He, 4He is widely used to get the temperature above 2 K, while 3He is used to obtain the temperature below 2 K. In this paper, a finite-element model (FEM) of the counter-flow tube-in-tube heat exchangers (CFHX) is established. According to the Laval nozzle model, the mass flow rate and the cooling capacity of the JT process are analyzed. Finally, this paper combines these models and uses MATLAB for programming. The influence mechanism of the CFHX length and the JT orifice diameter on the 4He and 3He JT effects are obtained.

Space sub-Kelvin refrigeration technology is an indispensable part of many deep space exploration missions. The dilution refrigerator (DR) is one of the sub-Kelvin refrigerators used in space missions. The space DR requires a closed-cycle design for a longer service life. The 3He Joule-Thomson (JT) cryocooler is an excellent choice among the space mechanical cryocoolers for precooling the space closed-cycle DR (CCDR) because it can provide a stable, vibration-free precooling environment. In this paper, the required cooling capacity of the CCDR's final precooling stage is calculated. The design goal of the 3He JT cryocooler is to obtain 3.6 mW of cooling power at or below 1.7 K. A third-stage counter-flow heat exchanger (CFHX3) is designed for the 3He JT cryocooler with an actual heat exchange efficiency higher than 99 %. A four-stage JT compression system consisting of two oil-free linear compressors is developed based on space compressors verified by many space missions of China. The JT expansion impedance consists of two orifices with diameters of 27 mu m and 26 mu m in series. Then, experiments are conducted on the coordination of the CFHX3, the JT expansion impedance, and the JT compression system. Hence, a hybrid 3He JT cryocooler is successfully designed, fabricated, and tested for the CCDR and obtains a noload temperature of 1.40 K with a power consumption of 277 W. Furthermore, with a power consumption of 320 W, the 3He JT cryocooler attains a cooling power of 3.75 mW at 1.54 K with temperature fluctuation lower than +/- 0.02 K.

The effects of microbial electrolysis cell (MEC) integration stage on two-stage anaerobic digestion (TSAD) of food waste (FW) were studied via semi-continuous experiments. The results showed that both MEC (with 1.2 V) integrations enhanced the performances of the TSADs, with the enhancement of electro-two stages being higher. The methane production of TSAD increased from 1.36 & PLUSMN; 0.04 L/L/d to 1.53 & PLUSMN; 0.05 L/L/d (electro-methanogenic stage) and 1.54 & PLUSMN; 0.04 L/L/d (electro-two stages) during the steady period. Electro-acidogenesis decreased propionic acid production and enhanced hydrogen production, while electro-methanogenesis promoted the conversion of volatile fatty acids to methane. The MEC integration improved energy recovery from the organic matter in FW by 11.65-16.15% and reduced the mass loss, with those of the electro-two stages being higher and the electro-methanogenic stage being dominant in the electro-two stages. The integration of MEC enhanced anaerobic fermentation by enriching Olsenella, norank_f__ST-12K33 and Proteiniphilum and improved methanogenesis by enriching Methanobacterium and Candidatus_Methanofastidiosum.

To enhance resource recovery from food waste (FW), a semi-continuous experiment was conducted to study simultaneous biohythane and volatile fatty acids (VFAs) production from it in a microbial electrolysis cell-assisted acidogenic reactor (MEC-AR). Anaerobic fermentation of FW at acid pH (3.71-5.19) produced CH4 through acclimating acid-tolerant methanogens. The MEC-AR with 1.2 V and pH 5.04 +/- 0.10 simultaneously produced 2.73 +/- 0.05 L/L/d biohythane (with 34.80 +/- 1.09% CH4, 14.95 +/- 0.86% H2, and 28.74 +/- 1.11% H2/ (H2+CH4)) and 19.39 +/- 0.44 g chemical oxygen demand/L VFAs during steady period. The pH of the fermen-tation liquid and MEC were the primary factors that influenced the production of biohythane and VFAs. No hydrogen was produced in the reactor at low pH (3.50-4.00) or no applied voltage. The MEC also affected the composition of VFAs with high acetic acid (65.43 +/- 2.42%) and low propionic acid (3.71 +/- 0.76%) contents and increased the relative abundances of Olsenella and Methanobacterium. Energy analysis showed that the MEC improved the energy efficiency of anaerobic fermentation of FW. This study thus provided a novel, efficient, and applicable strategy for resource recovery and valorization of FW.

Long-term semi-continuous experiments were carried out under three feedstock conditions to study the effects of mixing ratio and total solids (TS) content on temperature-phased anaerobic codigestion of rice straw (RS) and pig manure (PM). The results showed that biohythane only produced from the mixture with 6% TS content and its average content were 12.83 +/- 1.19% (hydrogen) and 23.68 +/- 1.12% (methane). Increasing mixture TS content and decreasing its RS ratio increased biohythane production and organic matter removal by creating a suitable process pH and increasing the anaerobic reaction rates. The highest biohythane production of the mixture reached 73.09 +/- 3.03 ml/g VS (hydrogen) and 235.81 +/- 9.30 ml/g VS (methane) at a mixing ratio of 5:1 and TS content of 6%. A variety of hydrogen-producing bacteria were found in the thermophilic reactor and Clostridium_sensu_stricto_1 played an important role. Butyric acid fermentation is the main hydrogen-producing pathway. Methanobacterium and Methanosaeta were dominant archaea in the mesophilic reactor.

The space 2 K cryogenic technology is one of the key supporting technologies for deep-space exploration. Superfluid helium cryostats were used to obtain the temperature below 2 K in early space missions. However, superfluid helium cryostats have been gradually replaced by space 2 K mechanical cryocoolers to reduce the weight of satellites and extend the lifetime of detectors. Recently, a space hybrid He-4 Joule-Thomson (JT) cryocooler operating at about 2 K is developed by our laboratory, which has a compact structure. The JT cycle, precooled by a two-stage thermally coupled pulse tube cryocooler (PTC), is driven by an efficient four-stage JT compression system. All the compressors used to drive the JT cycle and PTC in this hybrid JT cryocooler are designed for future space applications. This hybrid JT cryocooler reaches a minimum no-load temperature of 2.17 K and achieves the cooling capacity of 4.0 mW at 2.39 K.

In the area of space astronomy, some electronic detectors should be cooled to liquid helium temperature level to improve their sensitivity and reduce the background noise. A hybrid J-T cooler has been developed for future space application by our laboratory. The J-T loop is precooled by two-stage thermally coupled pulse tube cooler. There is no moving part at low temperature in this system which features low vibration electromagnetic interference. The hybrid J-T cooler has been experimental tested and cooling capacity of about 34.5mW@4.32K is achieved when supply pressure is 1.97MPa. Besides, when sufficient precooling power is provided for the J-T loop cooling capacity of 102.3mW at 5.02K is achieved. In this experiment, three oil free linear compressors are used to drive the J-T loop and a GM cooler is used to provide the precooling power for the J-T cooler. This J-T cooler will be the potential cryocooler for the future space detectors requiring cooling power of 100mW at < 6K.

A space 100 mW@4.5 K JT cooler is designed, manufactured and experimentally tested by our laboratory. The multi-orifice JT element is proposed to improve the performance of the JT loop. And compared to single orifice, the multi-orifice JT elements perform better. Cooling power of 100.3 mW@4.55 K is achieved when JT element is 4 * 20 mu m orifice and supply pressure is 2.0 MPa in open loop experiment. In closed loop experiment, three oil-free linear compressors are used to drive the JT loop, and cooling capacity 102.3 mW at 5.02 K is achieved. This JT cooler will be the potential cryocooler for the future space detectors working at 4.5 K.

>Cryogenics and its applications in space have made a remarkable amount of progresses over the last few decades. In the area of space astronomy, some electronic detectors should be cooled to 1–4 K to improve their performance[1,2]. So the miniature 1–4 K cryocooler for space application has become a key field for cryogenic research in recent

The rapid development of large-scale livestock husbandry has caused serious air pollution problems (e.g., The Tuzuoqi demonstration farm belonging to the Yili Group. The farm is located in the suburb of Hohhot City in northern China). In this study, the gases in typical areas of a large-scale dairy farm were sampled and measured for volatile organic compounds (VOCs), hydrogen sulfide, and ammonia concentrations. Fifty-two species of VOCs were identified. The VOCs emitted from the cowshed mainly consisted of halogenated hydrocarbons (16,960 mu g/m(3)), ketones (15,700 mu g/m(3)), esters (9889 mu g/m(3)), and sulfur compounds (3677 mu g/m(3)). The VOCs from the oxidation pond were mainly composed of halogenated hydrocarbons (21,940 mu g/m(3)) and ketones (3589 mu g/m(3)). The VOCs from the solid-liquid separation tank comprised halogenated hydrocarbons (32,010 mu g/m(3)), ketones (7169 mu g/m(3)), and sulfur compounds (1003 mu g/m(3)). The highest concentrations of ammonia and hydrogen sulfide were obtained from the milking parlor and solid-liquid separation tank, respectively. The ammonia concentration declined gradually due to the superposition of ammonia emitted from the cowshed and milking parlor. Analysis results of the influences of distance and meteorological factors on the dispersion of ammonia and hydrogen sulfide suggested that the dilution factors decreased with increasing distance from the emission source. Within distance ranges of 0-10 and 10-25 m, the concentration dilution factors were positively correlated with wind speed and temperature but negatively correlated with humidity and atmospheric pressure. The results of our work can provide a theoretical basis for the prevention and control of odorous gases in large-scale livestock farms. Implications: Gases in typical areas of a large-scale dairy farm were sampled, and a total of 52 species of VOCs were identified. The highest concentrations of ketones, sulfur compounds, and esters were obtained at the cowshed (15,700, 3677, and 9889 mu g/m(3), respectively). Within the distance ranges of 0-10 and 10-25 m, the concentration dilution factors were positively correlated with wind speed and temperature.

Integration of optics inside a detector-dewar-cooled-assembly (DDCA) is a good strategy to miniaturized infrared cameras in order to provide small payload systems with thermal vision capability for both military and civilian applications. The optical additional mass has to be very small in order to limit the cool-down time of the DDCA. However, reducing the mass of these optical systems results in a decrease of the resolution and impaction on the image quality, making them difficult to use in the high-performance and high sensitivity applications. In order to achieve better optical performances, a classical optical system which consisted of four lenses was integrated in the DDCA. By optimizing the heat transfer of the lens mount and using a miniature pulse tube cryocooler(MPTC) as the cooling source, the cooling time of the system was reduced. The lens mount and the lenses were cooled down to 80K in an hour by the MPTC with 45W input power. The total mass to be cooled is 100 g, where the mass of the lenses is 15 g. In the later prototypes, the mass of the lens mount can be greatly reduced by optimizing the installation of the detector and the lens mount, and the cooling time of the cryogenic camera integrated with the high-performance optical system can be reduced to an acceptable range by using the lens mount heat transfer optimization method described in this paper.

Key Laboratory of Space Energy Conversion Technologies of TIPC, CAS has developed a 4.5K Joule-Thomson (JT) cryocooler precooled by a multistage pulse tube cooler. In this paper, series of experimental research is carried out to explore the performance of the JT cooler at different operating conditions. When only the power consumption of JT compressors is considered, the coefficient of performance (COP) of the JT cycle is proposed to evaluate the performance of JT cycle. Experimental research is carried out to investigate the influence of supply pressure and JT orifice on cooling capacity and especially the COP of JT cooler. Experimental results suggest that cooling power of JT cooler increases as supply pressure increases and higher COP are gained because of rising flow resistance of JT orifice. Then JT orifices of different diameters are experimentally studied to explore the effect of flow resistance of JT orifice on the performance of JT cooler.