This paper reviews the primary scientific articles applicable to the logistics industry, and specifically those relating to cross-border e-commerce in China. The authors focused on reviewing the articles about the current status of cross-border e-commerce in China and the factors affecting its development, with the aim of highlighting literature gaps. The authors used a systematic literature review (SLR) to identify, gather, and analyze 60 primary papers selected from international peer-reviewed journals and international conference proceedings between 2001 and 2020. Chinese cross-border e-commerce has experienced a trend of steady progress, although several challenges remain. These challenges include, but are not limited to, low custom clearance efficiency, complex monitoring and supervision, tax rebate settlement challenges, payment risks, insufficient talent within the Chinese industry, and the lack of scientific management guidelines. The significant contributions of this paper include critical highlights of the current gaps and future research themes.

Ample quantities of solar and local biomass energy are available in the rural regions of northwest China to satisfy the energy needs of farmers. In this work, low-temperature solar thermal collectors, photovoltaic solar power generators, and solar-powered thermostatic biogas digesters were combined to create a heat, electricity, and biogas cogeneration system and were experimentally studied through two buildings in a farming village in northwestern China. The results indicated that the floor heater had the best heating effect. And the fraction of the energy produced by the solar elements of the system was 60.3%. The photovoltaic power-generation system achieved photovoltaic (PV) conversion efficiencies of 8.3% and 8.1% during the first and second season, respectively. The intrinsic power consumption of the system was 143.4 kW·h, and 115.7 kW·h of electrical power was generated by the system in each season. The average volume of biogas produced daily was approximately 1.0 m3. Even though the ambient temperature reached −25°C, the temperature of the biogas digester was maintained at 27°C ± 2 for thermostatic fermentation. After optimization, the energy-saving rate improved from 66.2% to 85.5%. The installation reduced CO2 emissions by approximately 27.03 t, and the static payback period was 3.1 yr. Therefore, the system is highly economical, energy efficient, and beneficial for the environment.

Previous studies showed that chicken manure and straws can be used as a feedstock in the production of methane during anaerobic digestions. The objective was to determine the best mixture of chicken manure and straw in the production of methane during anaerobic digestion. In this study the effect of three volatile solid (VS) rations on methane output, pH, hydrolase activity, and microbial community structure was determined. The optimal manure-straw VS ratio was M2 (9:1), where cumulative methane output reached a maximum of 227,660 ml kg -1 in 50 d. The cellulose activity was higher in the chicken manure to straw ratio of 9 than 4 or 1. The research showed that Megasphaera and Bacteroides were important cellulose-secreting bacteria. The results show: (a) during anaerobic digestion the cellulose and lignin contents were completely degraded; (b) protease, amylase, and lipase activities were higher in M2 (9:1) than M1 (1:0) or M3 (4:1); and (c) increasing amount of straw decreased bacteria and archaea diversity. Due to the addition of straw, the uniden-tified_Prevotellaceae had good physiological activity in the acidic environment between 5 and 30 d, Candidatus_Cloacimonas, unidentified_Lentimicrobiaceae, and Ruminiclostridium were the main archaea between 40 and 50 d.

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