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• HSP27 expression increased at both tissue and cellular levels after E. coli infection. • HSP27 overexpression enhanced the ability of IPEC-J2 to resist E. coli F18 infection. • RSK2 in the MAPK pathway may have a synergetic role with HSP27. Heat shock protein 27 (HSP27) plays an important role in protecting cells from various stress factors. This study aimed to investigate the function of HSP27 gene and its regulatory mechanism as infected by Escherichia coli (E. coli) at the tissue and cellular levels. Real-time PCR was used to detect the differential expression of HSP27 gene in F18 resistant and sensitive Sutai pigs and the differential expression upon E. coli F18ab, F18ac, K88ac bacterial supernatant, thallus infection and LPS induction in IPEC-J2. In addition, the HSP27 gene overexpression vector was constructed to detect the effect of the HSP27 gene overexpression on the adhesion of E. coli F18 to IPEC-J2, secretion of pro-inflammatory factors, and the expression of the upstream key genes in Mitogen-activated protein kinase (MAPK) pathway. Ribosomal S6 kinase (RSK2) is an important protein in the MAPK pathway. Therefore, the RSK2 gene overexpression vector was constructed and the number of colonies was counted after co-transfection of HSP27 and RSK2 gene. Results revealed that the expression level of HSP27 gene in resistant individuals in 11 tissues was higher than sensitive type. At the cellular level, the relative expression levels of HSP27 gene were increased after F18ab, F18ac bacterial supernatant, F18ab thallus infection, and LPS induction for 4 h (P < 0.01). The adhesion ability of E. coli F18ab to IPEC-J2 was significantly reduced after HSP27 gene overexpression (P < 0.01), and the concentration of pro-inflammatory factors in the HSP27 gene overexpression group was significantly reduced compared with the control group after F18ab infection (P < 0.05). Furthermore, the expression of RSK2 was significantly increased in HSP27 overexpression group upon F18ab infection (P < 0.01). The colonies quantitative results also showed that the number of colonies was significantly reduced after co-transfection of HSP27 and RSK2 gene. We indicated that the high expression of HSP27 gene may resist the inflammatory response caused by exogenous stress and enhance the ability of IPEC-J2 to resist E. coli F18 infection. RSK2 gene in the MAPK pathway may cooperate with HSP27 gene to participate in the immune response of the organism, which provides a theoretical basis for the study of the mechanism of anti- E. coli infection in piglets. [ABSTRACT FROM AUTHOR]

• Indoor thermal environment and AC usage behavior was investigated for low-quality centrally heated dwellings. • 90% of AC trigger temperature is 15 ℃ for the living room and 14 ℃ for the bedroom. • The heating demand drivers of cool housing are identified by heteroskedasticity-robust Ordinary Least Square. • The study presents new knowledge for appropriate way to meet actual heating demand while reducing energy use. • Relationships between indoor temperature, heath and energy use are discussed. In northern China, district heating systems without terminal control typically serve thousands of end-users, thus inevitably some users suffer from insufficient warmth and others are overheated indoors due to hydraulic imbalances. This paper aimed to understand the indoor thermal conditions and the actual heating demand in low-quality centrally heated dwellings. The driving force of heating demand was analyzed based on a smartphone survey of 233 households in cold climates, and field measurements of winter indoor thermal environment and AC supplemental heating behavior were conducted in a sample of 13 cool dwellings. Logistic regression and heteroskedasticity-robust Ordinary Least Squares were adopted to assess AC usage patterns and driving forces of heating demand, respectively. New knowledge has been gathered regarding average temperatures of 17.4 ℃ and 16.8 °C in cool housing living rooms and bedrooms, respectively, outside the human thermal comfort zone. Simultaneously, intermittent and partial AC usage patterns induced by time and air temperature were observed in these cool end-users for the comfort. The average daily running time of AC devices was 2.0 h for the living room and 1.8 h for the bedroom. There were statistically significant base linking occupants' heating demands to education level, household income, tenure type, presence of children, thermal experience and heating system. However, it was not a significant factor for household size. In addition, a rebound effect of building energy efficiency improvements on the interior temperature was also noticed. The results of this study shed light on better and target-oriented residential internal temperature or heating system design for both thermal comfort requirements and energy-savings. [ABSTRACT FROM AUTHOR]

• The pore diameter and pore number of AAC were obtained through the image. • The air pores of AAC were generated, and the AAC model was built by software. • The relationship between thermal conductivity/porosity and pore size was obtained. The pore structure has great influence on the mechanical properties and thermal conductivity of autoclaved aerated concrete(AAC). In this study, through the binary processing of the surface image of AAC, the pore diameter and number of AAC were obtained. Based on Monte Carlo method, the spherical coordinates of the air pores of AAC were generated by MATLAB software, and then they were imported into ANSYS software for modeling and grid generation. By comparing the pore size distribution and thermal conductivity between the finite element model and AAC product, to some extent, the finite element model in this paper is feasible. By the finite element analysis, the thermal conductivity is inversely proportional to the porosity and directly proportional to the pore diameter. Based on the thermal conductivity prediction model of porous materials, the mathematical models of porosity and thermal conductivity, pore diameter and thermal conductivity of AAC were established. [ABSTRACT FROM AUTHOR]

• The strength damage caused by dissolution and leaching of calcium ions. • ·The microscopic structure evolution with chemical corrosion of ion solution. • ·A constitutive model of reactive powder concrete (RPC) under the cooperative action of ion corrosion and loading. The damage of dissolution and leaching of calcium ions caused by ion corrosion to the macroscopic mechanical properties of RPC is investigated, and the microscopic mechanism of ion corrosion is revealed. Through the unconfined compression test, the effects of different ion corrosion types on the unconfined compression strength (UCS) and failure morphology of RPC, and standard cement mortar (SCM) were studied. The effect of ion corrosion on the micro-structure and element ratio of hydration products was analyzed by SEM/EDS. In addition, through the calcium leaching model test, the effect of NaCl and MgSO4 corrosion on calcium dissolution and destruction of RPC slabs was studied, and the composition of the precipitate was determined by XRD analysis method. A damage constitutive model of RPC with ion corrosion and loading coupling was established, providing a theoretical basis for calculating the ion corrosion depth. The results show that RPC has better resistance to the damage of calcium leaching caused by ion corrosion than SCM. After 90 days of chloride ion and sulfate ion corrosion, calcium precipitation and recrystallization appeared on the surface of RPC, where an insoluble substance formed, and the ion corrosion depth was 13.32 mm and 11.30 mm, respectively. [ABSTRACT FROM AUTHOR]