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A parallel power/refrigeration cogeneration Kalina cycle (PPR-KC) system with adjustable refrigeration/power ratio that developed on the basis of the triple-pressure Kalina cycle system was analyzed. The PPR-KC system can produce refrigeration with temperature ranging in either air conditioning or ice making by switching the exhaust refrigerant vapor to the mid-pressure absorber or to the low-pressure one. The influences of the dilute solution from generator to the destination of either mid-pressure absorber (plan A) or low-pressure absorber (plan B) via recuperators on the performances of the PPR-KC system for air conditioning were investigated. The results show that the PPR-KC system matches well the heat source in cascade arranged boiler and generator thus showing excellent thermal performance by optimizing the solution concentrations, boiler superheat and other parameters. Under the given temperatures of heat source 400°C and cooling water 30°C respectively, the variation trends of the cycle parameters and performances of both plan A and plan B are presented. The power recovery efficiency of plan B is about 1.6% higher than that of plan A. When boiler bubble point temperature difference increases from 20 K to 60 K the refrigeration/power ratio of plan B climbs from 0.475 to 1.192.

Medication adherence to antiretroviral therapy (ART) among elderly people living with HIV (PLWH) is of serious concern. Our study aimed to understand the medication adherence of elderly PLWH under ART based on the health belief model (HBM). A baseline survey with a total of 529 elderly PLWH was conducted in Sichuan. Logistic and linear regression analysis, mediation analysis, and path analysis based on prior evidence were used. Only self-efficacy showed direct associations with medication adherence in the last four days (ORm = 1.37, 95%CI: 1.11, 1.70) and the last month (ORm = 1.39, 95%CI: 1.18, 1.63) in the multivariate analysis. Self-efficacy mediated the relations between perceived benefits, perceived barriers, cues to action and medication adherence. Inner relations existed within the HBM. In addition to the direct effects, perceived benefits (β = 0.149, p = 0.031; β = 0.093, p = 0.005), perceived barriers (β = -0.070, p = 0.008; β = -0.062, p = 0.012), and cues to action (β = 0.184, p = 0.013; β = 0.135, p = 0.014) showed indirect effects on medication adherence in the last four days and the last month, respectively. HBM may be effective in predicting medication adherence of elderly PLWH, and self-efficacy may be a crucial predictor and mediator. Efforts should be focused on how to enhance elderly PLWH's self-efficacy without neglect of other medication beliefs.

Anion Exchanger 1 (AE1, SLC4A1) is the primary bicarbonate (HCO3-) transporter expressed in erythrocyte membranes where it mediates transport of CO2between lungs and other tissues via import/export of bicarbonate. It is also a key regulator of erythrocyte structure and antigenic recognition. Previous biochemical studies, and a low-resolution crystal structure of the transmembrane domain have provided initial insight into AE1 structure and function. However, key questions remain regarding substrate binding and transport as well as the mechanism of inhibition. The orientation of the intracellular domain as well as the localization of lipid and sterol binding sites also remain enigmatic. We herein present seven novel high resolution cryo-EM structures of the full length human transporter in the apo, bicarbonate-bound, and several inhibitor-bound states combined with uptake- and computational studies. To our knowledge, these studies represent the first full length human, and substrate bound, SLC4 transporter structure. Our results reveal important molecular details about substrate binding and transport, as well as the diverse mechanisms of AE1 inhibition by both research chemicals and prescription drugs. We also provide novel insights into the full-length transporter architecture, identify the conformational space of the Diego blood antigen system and elucidate multiple lipid and sterol binding sites.

Objective. The Chinese men who have sex with men (MSM) population is suffering from a high HIV infection rate owing to unprotected anal sex. The Health Belief Model (HBM) has been proven to be an effective frame associated with behavior maintenance. Based on HBM, we analyzed the beliefs associated with consistent condom use behavior with regular and nonregular partners among MSM to better provide targeted interventions and services. Methods. A study was conducted in Sichuan Province, China, from November 2018 to April 2019, and 801 eligible participants were recruited by snowball sampling. Sociodemographic characteristics, AIDS-related characteristics, sexual behaviors, condom use behavior, and dimensions of HBM were investigated. Univariate, single multivariate, and summary multivariate models were employed to analyze the factors associated with consistent condom use. Results. Of all participants, 39.1% and 53.6% had had anal sex with regular and nonregular partners in the last six months, respectively. Only 56.5% of them had used condoms consistently with regular partners, and only 60% of them had used condoms consistently with nonregular partners. When taking consistent condoms use with regular partners as the dependent variable, the dimensions of perceived threats ( ORM = 1.28 , 95% CI: 1.10, 1.49), perceived barriers ( ORM = 0.70 , 95% CI: 0.60, 0.82), self-efficacy ( ORM = 1.23 , 95% CI: 1.14, 1.32), and cues to action ( ORM = 1.21 , 95% CI: 1.02, 1.43) showed significant associations with the dependent variable. When taking consistent condoms use with nonregular partners as the dependent variable, the dimensions of perceived barriers ( ORM = 0.77 , 95% CI: 0.67, 0.89), self-efficacy ( ORM = 1.22 , 95% CI: 1.13, 1.32), and cues to action ( ORM = 1.53 , 95% CI: 1.30, 1.80) showed significant associations with the dependent variable. Conclusions. More attention should be focused on how to decrease the obstructive factors of condom use, how to improve the confidence of condom use, and how to layout more cues to action to promote consistent condom use behavior with regular and nonregular partners during anal sex among Chinese MSM.

OBJECTIVE Although methadone for addiction treatment (MAT) has been widely used in China, the low adherence rate in MAT clinics poses a great challenge. We aimed to investigate the factors related to the adherence of heroin-dependent patients to MAT based on the Health Belief Model (HBM) in Sichuan, China. METHODS A cross-sectional structured interview was conducted between August and November 2018. Stratified multi-stage sampling was carried out. A total of 581 participants were enrolled from 5 clinics and completed the face-to-face structured interview. Univariate, adjusted logistic regression, multivariate logistic regression analysis and the structural equation modeling (SEM) were employed to explore the association between constructs of HBM and adherence to MAT among heroin-dependent patients. RESULTS The adherence rate of MAT was 79.3% in the past 6 months. Among all constructs of HBM, self-efficacy (AOR: 1.16, 95% CI: 1.10, 1.22), perceived benefits (AOR: 1.05, 95% CI: 1.00, 1.10) and perceived barriers (AOR: 0.87, 95% CI: 0.77, 0.98) were associated with adherence to MAT. Self-efficacy was directly associated with adherence to MAT (β = 0.347, P < 0.05). Perceive benefits (β = 0.276, P < 0.01) and perceived barriers (β = -0.241, P < 0.05) were directly associated with self-efficacy. However, perceived benefits (β = 0.096, P < 0.01) and perceived barriers (β = -0.084, P < 0.01) were only indirectly associated with adherence to MAT. CONCLUSION The adherence of heroin-dependent patients to MAT can be explained by self-efficacy, perceived benefits and barriers. Self-efficacy plays a significant role as a mediating variable. Future interventions should be considered to improve patients' self-efficacy to MAT.

The shell side flow fields of both sextant and trisection helical baffle heat exchangers are presented on meridian and multilayer hexagon slices. It verifies that the performance of sextant schemes is better than those of the other kinds of helical baffle heat exchangers. The main mechanisms are due to the restricted leakage flow in the minimized gaps with increased baffle number and by one row of tubes dampen the leakage flow in the circumferential overlapped area of the adjacent helical baffles. The performance features were simulated on two different angled sextant helical heat exchangers and each compared with two trisection ones of either identical helical pitch or identical incline angle. The results verified that the performances of helical heat exchangers are mainly determined by the helical pitch rather than the baffle incline angle. The average values of comprehensive index hoΔpo−1/3 of the trisection helical schemes T-24.1° and T-29.7° are correspondingly 3.47% and 3.34% lower than those of the sextant ones X-20° and X-25° with identical helical pitches. The comparison results show that the average values of shell side h.t.c. ho and comprehensive index hoΔpo−1/3 of the optimal dual helix sextant scheme DX30° are respectively 7.22% and 23.56% higher than those of the segment scheme S100.

Covertly using heroin during methadone maintenance treatment (MMT) is very common among heroin-dependent patients, which has posed threats to the physical health of heroin-dependent patients and social safety. Covertly using heroin may be influenced by many factors, especially social capital. Therefore, we aimed to investigate the relationship between behaviors of covertly using heroin during MMT and social capital heroin-dependent patients in Sichuan Province, China. A cross-sectional study was conducted between October and November 2018, with a total of 581 heroin-dependent patients participating in the study. In addition to socio-demographic characteristics and heroin use related behaviors, the questionnaire also included the measures of social capital: social network (SN), social support (SP), community participation (CP) and social trust (ST). Multivariate logistic regression analyses were used to estimate the association between different measures of social capital and heroin use. The prevalence of covertly using heroin of heroin during MMT was 31.0% among our participants in the 6 months before the study. After adjusting for socio-demographic factors and heroin-use related variables, SN (OR = 0.85, 95% CI: 0.76–0.95), SP (OR = 0.89, 95% CI: 0.83–0.95), and ST (OR = 0.88, 95% CI: 0.81–0.95) were significantly associated with heroin use. Results suggest that social capital may have a protective effect on behavior of covertly using heroin during MMT, which should be consider in the interventions for heroin-dependent patients, in order to reduce the incidence of heroin use during MMT as well as improve the compliance of MMT.

Frizzled receptors (FZDs) are class-F G-protein-coupled receptors (GPCRs) that function in Wnt signalling and are essential for developing and adult organisms1,2. As central mediators in this complex signalling pathway, FZDs serve as gatekeeping proteins both for drug intervention and for the development of probes in basic and in therapeutic research. Here we present an atomic-resolution structure of the human Frizzled 4 receptor (FZD4) transmembrane domain in the absence of a bound ligand. The structure reveals an unusual transmembrane architecture in which helix VI is short and tightly packed, and is distinct from all other GPCR structures reported so far. Within this unique transmembrane fold is an extremely narrow and highly hydrophilic pocket that is not amenable to the binding of traditional GPCR ligands. We show that such a pocket is conserved across all FZDs, which may explain the long-standing difficulties in the development of ligands for these receptors. Molecular dynamics simulations on the microsecond timescale and mutational analysis uncovered two coupled, dynamic kinks located at helix VII that are involved in FZD4 activation. The stability of the structure in its ligand-free form, an unfavourable pocket for ligand binding and the two unusual kinks on helix VII suggest that FZDs may have evolved a novel ligand-recognition and activation mechanism that is distinct from that of other GPCRs.

The flow and heat transfer performances were investigated on unilateral ladder type helical baffle heat exchangers (ULHBHXs) with different geometrical structures in half cylindrical space and compared with those of the segmental baffle heat exchangers (SBHXs). The unilateral ladder type helical baffles consist of two alternate groups of plates, the folded baffles (Baffles A) and the segment ones (Baffles B). The studied ULHBHXs include the combination schemes of different Baffle A with different baffle pitches (40, 60, 80 mm) and different projection length of inclined section (l = 60, 72, 84 mm and a plane one). Visualization methods of nephograms were adopted on special slices to clearly reveal the impacts of baffle configurations on flow patterns. The numerical results show that the shell-side heat transfer coefficients of the ULHBHX schemes with folded Baffles A are superior but the comprehensive indexes are inferior to those of the corresponding plane ones, and all the helical schemes are superior to those of the segmental schemes. The average ratios of shell-side heat transfer coefficient, pressure drop and comprehensive indexes hoΔpo−1 and hoΔpo−1/3 of all the twelve ULHBHX schemes over those of the SBHX ones with corresponding baffle pitches are 1.166, 0.670, 1.851 and 1.352, respectively.

Numerical simulations were conducted on nine U-tube electric heater models of 45 U-tubes with a unique tube layout of one-plus-two units, including eight helical baffle schemes of different baffle ...

To minimize the abrasion of sharp-corners of holes of inclined baffles manufactured by 2D laser beam cutting machine on the tubes, the application of axial separation with small inclined angle helical baffles is a simple alternate, which creates greater helix pitch for suitable cross section area. Numerical simulation on the flow and thermal performances were conducted on three axial separation helical baffle electric heaters with equivalent angles 15°, 20° and 25° using 10° inclined baffles, three normal helical baffle ones and two segment baffle ones spanned respectively 200 and 250 mm. Each electric heater comprises 27 U-tubes on equilateral triangle layout with nine one-plus-two units. The secondary flow imposed plug flow pattern and leakage flow were demonstrated for helical schemes. The axial separation helical baffle schemes have obvious merits in the heat transfer coefficient, comprehensive index and the temperature uniformity of the electric heating tubes over those of the segment baffle ones. The average heat transfer coefficient and the comprehensive index ( h ·Δ p −1/3 ) of the modified axial separation helical scheme with equivalent angle 20° using 10° baffles are respectively 37.8% and 26.0% higher while its average tube wall temperature is 95.6 K lower than those of the segment scheme spanned 200 mm.

A unilateral ladder type helical baffle heat exchanger (ULHBHX) which is a novel countercurrent U-tube heat exchanger was proposed and investigated for better characteristics of high heat transfer coefficient, low resistance, anti-vibration and anti-fouling with a spiral flow pattern than those of the conventional segment one. The numerical model of ULHBHX was established and simulated by CFD software with 38 heat transfer tubes and 2 rod and spacing tube assemblies in the lower half cylindrical space under the parameters of subcooling of a high pressure feedwater heater in power plants. Different views such as on baffle-parallel slices and polygonal slices were presented to show the flow patterns of the main helical flow, secondary vortex flow and the leakage flow. The influences of geometrical parameters of baffle pitch and projection length of the inclined section on heat transfer and pressure drop were discussed quantitatively. The results show that the shell-side heat transfer coefficient h o of the ULHBHXs is 13.2%–18.2%, with an average of 16.0%, higher than those of the corresponding segment schemes, and the comprehensive index h o Δ p o −1/3 is 15.7%–46.4%, with an average of 28.3%, higher than those of the corresponding segment schemes with identical baffle pitches in the discussed range.

The heat transfer performance of a novel type trisection helical baffle vertical condenser was experimentally investigated. The testing schemes have a common shell and replaceable tube bundles, including six tube bundles with different structured trisection helical baffles and a segmental one. The investigation is aimed at revealing the impacts on the heat transfer performance of structural improvements for facilitating condensate drainage, including inclined helical baffles of variable angles, dual threads and bent tail edges. The experimental results show that the best scheme, which adopts dual thread variable angled baffles with bent tail edges, has the average shell side heat transfer coefficient 131.8% higher than that of the segmental one. Taking the shell side heat transfer coefficient as the evaluation index, the single thread variable angle schemes are on average 25.47% higher than the single thread fixed angle ones; the dual thread variable angle schemes are on average 15.74% higher than the single thread ones; and the schemes with bent tail edges are on average 6.37% higher than the corresponding ones without bent tail edges. The results give a prospective way to overcome the deficiency of inferior heat transfer performance of the conventional segmental baffled vertical condenser to that of the horizontal one.

A gas and steam mixture cycle (GSMC) is presented with a mixture of LNG/O2 (liquid natural gas/oxygen) combustion product and feedwater as working medium, integrating features of high efficiency power generation, peak shaving, energy storage and CO2 capture. The liquefied oxygen is produced during off-peak hours. During the operation hours, the cryogenic liquids of both LNG and oxygen are pumped to a high pressure and preheated before entering the combustors through the burners. The combustion product heats and mixes with the atomized feedwater to form supercritical H2O/CO2 mixture vapor for power generation in a turbine unit. The CO2 vapor is separated from condensate water in the condenser and liquefied by the cryogenic liquids of both LNG and oxygen after being compressed to a higher pressure. The circulation feedwater is injected to the annular channel between flame tube and shell cylinder of modular combustor via feedwater heating system. The results show that under the conditions of turbine inlet parameters of 40 MPa/800 °C and condensation temperature of 30 °C, the output power efficiency based on the thermal value of LNG fuel is 49.2% and the equivalent net efficiency is 46.4%, which accounts for 1/4 off-peak electricity consumption for liquid O2 production.

Axial separation is a novel baffle connection configuration of circumferential overlap helical baffle heat exchangers which makes baffle incline angle seriation possible. The adjacent baffle plates are separated by sleeve tubes to form a greater pitched helix for enhancing heat transfer under required pressure drop with the least number of molds for reducing baffle manufacture cost. Numerical simulations of flow and heat transfer performances were conducted and the calculation results were verified by the experimental ones. Performance investigation was conducted on eight normal trisection helical baffle schemes with baffle incline angles from 15° to 23° and five axial separation schemes of equivalent 17–22° angles using 15° baffles. In the calculation scope the average deviations of heat transfer coefficients and pressure drops of the normal helical schemes are respectively about −1.97% and −8.11% per 1° deviation of incline angle. The axial separation schemes using 15° baffles with equivalent 21° and 22° incline angles have deviation values of heat transfer coefficient 1.21% and 1.33% lower and pressure drop 4.96% and 5.55% higher respectively than those of the normal 21° and 22° incline angle schemes. By adopting axial separation approach the seriation step of baffle incline angles can be extended to 8°.

The shell-side flow and heat transfer performance in half-cylindrical desuperheating zones of high pressure feedwater heaters were simulated by Fluent. The investigated structures include three ladder type helical baffle heat exchangers, i.e. the two unilateral ladder types with folded and inclined plane strip baffles, and the bilateral plane type, and two comparative schemes of eggcrate support type and double-segmental type and all baffle types are of three different baffle pitches. The visualized flow patterns in the desuperheating zone were demonstrated on special slices to clearly reveal the mechanisms and impacts of baffle configurations and geometrical parameters on thermal-hydraulic performances. The numerical results show that the shell-side heat transfer coefficients ho of all ladder type helical models are superior to those of both eggcrate support and double-segmental ones, among which the bilateral plane model has the best performances. The average values of ho and evaluation indexes hoΔpo−1 and hoΔpo−1/3 of nine helical models raise 2.99%, 149.50% and 36.26% respectively in contrast to those of the corresponding double-segmental models, and the average values of evaluation performance η for schemes of three baffle pitches 80, 120 and 160 (mm) are respectively 1.202, 1.367 and 1.525.

The roles of Y-family DNA polymerases and the regulation mechanisms are not well defined in Archaea. In this study, we performed in vitro and in vivo characterization of the physical interaction between the archaeon Sulfolobus solfataricus Y-family DNA polymerase (SsoPolY) and three eukaryote-like Orc1/Cdc6 proteins (SsoCdc6-1, SsoCdc6-2, and SsoCdc6-3). The effect of SsoCdc6-2 was the strongest, and the three SsoCdc6 proteins were shown to have very different effects on the function of SsoPolY. SsoCdc6-2 inhibited both the DNA-binding activity and DNA polymerization activity of SsoPolY on the DNA substrates containing mismatched bases, while it formed a large complex with SsoPolY and stimulated DNA-binding activity on paired primer-template DNA substrates. SsoCdc6-2 and S. solfataricus PCNA (SsoPCNA) showed a cooperative effect on polymerization by SsoPolY on paired DNA templates, but SsoCdc6 reduced the stimulating effect of SsoPCNA on this polymerization on mismatched DNA substrates. Therefore, we uncovered a DNA substrate-dependent SsoCdc6/SsoPolY interaction mechanism. This is the first evidence for a physical and functional linkage between archaeal eukaryote-like Orc1/Cdc6 proteins and Y-family DNA polymerase.

Archaeal DNA replication machinery represents a core version of that found in eukaryotes. However, the proteins essential for the coordination of origin selection and the functioning of DNA polymerase have not yet been characterized in archaea, and they are still being investigated in eukaryotes. In the current study, the Orc1/Cdc6 (SsoCdc6) proteins from the crenarchaeon Sulfolobus solfataricus were found to physically interact with its DNA polymerase B1 (SsoPolB1). These SsoCdc6 proteins stimulated the DNA-binding ability of SsoPolB1 and differentially regulated both its polymerase and nuclease activities. Furthermore, the proteins also mutually regulated their interactions with SsoPolB1. In addition, SsoPolB1c467, a nuclease domain-deleted mutant of SsoPolB1 defective in DNA binding, retains the ability to physically interact with SsoCdc6 proteins. Its DNA polymerase activity could be stimulated by these proteins. We report on a linkage between the initiator protein Orc1/Cdc6 and DNA polymerase in the archaeon. Our present and previous findings indicate that archaeal Orc1/Cdc6 proteins could potentially play critical roles in the coordination of origin selection and cell-cycle control of replication.

Layered cobalt oxide thin films with tilted structures exhibit large light-induced transverse voltage signals due to the transverse thermoelectric effect and have great potential applications in uncooled broad-band light detectors. In this paper, we investigated the photoresponse in c-axis tilted Bi 2 Sr 2 Co 2 O y thin films coated with a layer of nano-structured silver light absorber by using a 532 nm continuous wave laser as the incident light. The incidence direction of the laser beam was directly perpendicular to the sample surface. The laser spot was located at the centre position between the two electrodes and its diameter was about 2 mm. The induced lateral voltage signals were recorded using a 2400 Keithley source meter. Open-circuit voltage signals were observed when the sample surface was illuminated by the 532 nmradiation. Appropriate lateral size and thickness of the nano-structured silver layer can increase the photo-thermal-electric conversion efficiency in this photoresponse process due to the effective absorption of the light at the absorption layer, leading to the improvement in voltage sensitivity. The result offers important guidance of designing the light absorption layer for high performance broad-band light detectors based on the light-induced transverse voltage effect.

Master regulators, which broadly affect expression of diverse genes, play critical roles in bacterial growth and environmental adaptation. However, the underlying mechanism by which such regulators interact with their cognate DNA remains to be elucidated. In this study, we solved the crystal structure of a broad regulator Ms6564 in Mycobacterium smegmatis and its protein-operator complex at resolutions of 1.9 and 2.5 A, respectively. Similar to other typical TetR family regulators, two dimeric Ms6564 molecules were found to bind to opposite sides of target DNA. However, the recognition helix of Ms6564 inserted only slightly into the DNA major groove. Unexpectedly, 11 disordered water molecules bridged the interface of TetR family regulator DNA. Although the DNA was deformed upon Ms6564 binding, it still retained the conformation of B-form DNA. Within the DNA-binding domain of Ms6564, only two amino acids residues directly interacted with the bases of cognate DNA. Lys-47 was found to be essential for the specific DNA binding ability of Ms6564. These data indicate that Ms6564 can bind DNA with strong affinity but makes flexible contacts with DNA. Our study suggests that Ms6564 might slide more easily along the genomic DNA and extensively regulate the expression of diverse genes in M. smegmatis.