High content of active component, low electrostatic sensitivity and superior long-term storage stability endow n-Si powder unique advantages for application in nanoenergetic composites. In this ...study, hydrophobic and corrosion-resistant Si@PVDF nanostructured energetic films with different stoichiometric ratios are successfully prepared by electrospinning technique. The energetic characteristics are systematically investigated in terms of thermal analysis, open-air combustion and constant-volume combustion. The results show that Si@PVDF films are microscopically composed of fibers with diameters of about 200–300 nm. With the increase of stoichiometric ratio, more and more n-Si aggregates are found on the surface of fibers. When Si@PVDF is stored in deionized water (50 °C) or NaOH solution (50 °C, 3 mol/L) for 72 h, around 100% and 73.3% of n-Si is retained. Si@PVDF can be thermally ignited, with appreciable heat and pressure output, and the combustion behaviors are strongly affected by the stoichiometric ratio and the environmental conditions. As a comparison, physically mixed Si/PVDF cannot maintain a self-sustained combustion. Through the coupled thermal analysis and mass spectrometry analysis, combined with the morphological and structural characterization of the solid residues, the reaction mechanism of Si@PVDF at a low heating rate is preliminarily obtained.
► Thermoelectric devices united with PV/T panel can cool rooms, heat water in summer and heat rooms in winter. ► The simulation results in summer have been validated by experiment. ► The system can ...be applied conveniently and operates quietly.
Buildings composited with thermoelectric cooling and heating systems use solar energy to cool rooms in summer and heat rooms in winter via thermoelectric devices and photovoltaic/thermal (PV/T) dual function modules. In summer, the thermoelectric device works as a Peltier cooler when electrical power supplied by PV/T modules is applied on it. The cold side absorbs heat from indoor to decrease the temperature of the room. In the meanwhile, the thermal energy gained both from the hot side and PV/T system is collected to heat domestic water by heat pipes. In winter, the voltage applied on thermoelectric device is reversed with PV/T modules being power and heat source simultaneously to thermoelectric device and then thermoelectric device could release heat to increase the temperature of the room. The experiments has been done in a model room whose volume is 0.125m3, in summer condition, using solar panel whose area is 0.5m2. The minimum temperature 17°C is achieved, with COP of the thermoelectric device higher than 0.45. The temperature of water in the storage tank with a volume of 18.5L has risen about 9°C. The thermal efficiency of the system is 12.06%. This simple and environmentally friendly can reduce cooling and heating load in room.
Timber is cost-effective and environmentally-friendly, which is a potential material for sustainable buildings, but its fire safety is still a significant concern. In this work, we investigate the ...burning behaviors of different types of woods and their self-extinction mechanism under external radiation. A unique near-limit flame is observed when the irradiation is above a critical value of about 40 kW/m
2
. Such a near-limit flame is weak, blue, and discrete that tends to attach to the wood residue surface, different from the normal buoyancy-controlled sooty yellow flame. If the irradiation is low (< 40 kW/m
2
), the yellow flame extinguishes and transits directly to smoldering at the mass flux of about 4 g/m
2
s. However, above the critical irradiation level, the yellow flame transits to the blue flame that does not extinguish until the mass flux of around 1 g/m
2
s, extending the flame extinction limit of timber materials. The near-limit blue flame may appear only if the char surface temperature exceeds 700°C. Two critical conditions are hypothesized for this unique blue flame, (I) in-depth pyrolysis (mainly lignin) sustained by the internal smoldering combustion, and (II) the hot surface maintained by large external radiation to extend the flammability limit. This unique blue flame may play an essential role in the transition between flaming and smoldering and help evaluate the fire risk of timber materials under real fire scenarios.
Graphical abstract
In the enthalpy difference lab with a solar simulator, the performance of the indirect expansion solar-assisted multi-functional heat pump (IX-SAMHP) can be tested in stable external environment ...quantificationally. In this paper, the performances of the IX-SAMHP working in the solar water heating mode and solar space heating mode were compared under different conditions. The experimental results indicate that the evaporating heat exchange rate and condensing heat exchange rate were synthetically effected by the evaporating and condensing temperature in the solar water heating mode. Moreover, compared with the situation without irradiation, when the irradiation was 500 W/m2, the evaporating heat exchange rate and condensing heat exchange rate increased by 37.4% and 32.3%, respectively. In the solar space heating mode, when the irradiation increased from 0 W/m2 to 500 W/m2, the heating capacity increased by 20.4%. In the second-law analysis, the calculating results demonstrate that the exergy efficiency of the IX-SAMHP would be enhanced by inputting solar energy to the evaporator.
•An indirect expansion solar-assisted multi-functional domestic heat pump is proposed.•The system was tested in steady environment temperature and irradiation.•The heating capacity in space heating mode was measured by air-enthalpy method.•Heat exchange rate in different working modes were tested under different conditions.•Exergy efficiency was compared between different irradiation.
Purpose
Coexistence of frailty and hemodialysis is related to higher risk of hospitalization, falls and mortality. Given the potential reversibility of frailty, reaching the epidemiology of frailty ...in hemodialysis is of great importance. However, estimates of the prevalence of frailty in patients on hemodialysis vary widely. We tried to synthesize the existing body of literature on the prevalence of frailty in patients on hemodialysis.
Methods
We searched Pubmed, Embase, Web of Science and Cochrane for studies of the prevalence in patients on hemodialysis. The prevalence of frailty was synthesized across eligible studies using a random-effects model. We explored potential origin of heterogeneity in the estimates by meta-regression analysis.
Results
Prevalence range from 6.0 to 82.0% and the pooled prevalence of frailty in patients on dialysis was 34.3% (95% confidence interval (CI) 24.5–44.1%;
z
= 6.87;
p
= 0.00). The pooled estimates of prevalence for patients aged < 55, 55–65, and ≥ 65 were 56.0% (95% CI 28.9–83.2%;
z
= 4.04;
p
= 0.00), 32.3% (95% CI 22.9–41.7%;
z
= 6.74;
p
= 0.00), and 20.3% (95% CI 7.9–32.8%;
z
= 3.2;
p
= 0.00), respectively. There were no significant relationships between frailty in hemodialysis and factors such as years of publication, sample size (continuous), sample size(> 500 vs ≤ 500), diagnostic method (the Fried Frailty vs other), country (Europe & USA vs Asia) and duration of hemodialysis.
Conclusions
Frailty influences almost three in ten patients on hemodialysis. Understanding the underlying pathophysiology mechanisms and weakening the impacts of frailty in patients on hemodialysis are called on to action in the future work.
This paper has analyzed the asymmetric flow effect of fire-induced thermal flow in a horizontal tunnel under the natural ventilation condition by conducting large eddy simulations (LES). The key ...objective is to reveal and to have a better understanding of the asymmetric flow effect caused by the upstream and downstream tunnel length difference. The mechanism behind it can be explained based on the conservation of mass and dynamic force analysis on the smoke and fresh air. The strength of the asymmetric flow effect is characterized by the mass flow rate of the induced longitudinal flow (net mass flow rate of a cross-section). An empirical correlation to predict the induced longitudinal mass flow rate is proposed. Furthermore, the law of smoke and air flow distribution within a horizontal tunnel is established. The proportion of smoke (or air) flowing out (or coming in) through the opening increase (or decrease) linearly with the increasing distance between that opening to the fire location. The variation of the air flow with the longitudinal fire location in a tunnel is more sensitive than the smoke flow. Results have shown that as the fire approaches the tunnel exit from the middle of the tunnel, the smoke spilling out through this opening is reduced from 50% to 40%, while the fresh air incoming from this opening is increased from 50% to 100% and vice versa.
In this study, a two-stage system known as the PV/T-ST system with a series photovoltaic/thermal (PV/T) module and a solar thermal (ST) collector combining thermoelectric conversion technology is ...proposed. In the daytime, the PV/T module generates power and captures low-temperature heat simultaneously. The ST module achieves secondary heating of water and secondary thermal-electric output by the thermoelectric generators (TEG). In the nighttime, the water heated by day continues to circulate, providing heat for TEG, thus achieving round-the-clock electrical output. Theoretical research reveals that the system’s total electrical power reaches its maximum value at 11:57, measuring 97.43 W. The maximum heat gain amounts to 380.67 W. During the night, TEG operates continuously and experiences a gradual decline in electrical output, with an average electrical efficiency of 0.43%.
•A novel MC-LHP-PV/T heat and power system was experimentally investigated.•New PV/T system achieved 18.55% higher solar efficiency compared to existing ones.•A lower inlet water temperature led to ...the increased solar thermal efficiency.•A higher water flow rate help increase the solar thermal efficiency.•A higher ambient temperature led to the increased solar thermal efficiency.
This paper aims to experimentally investigate a novel solar Micro-Channel Loop-Heat-Pipe Photovoltaic/Thermal (MC-LHP-PV/T) system which, making its first attempt to employ the co-axial tubular heat exchanger as the condenser, PV-bound multiple micro-channel tubes array as the PV/evaporator, the upper end liquid header with tiny holes as the liquid header and liquid/vapour separator, and the upper end vapour header as the vapour collector and distributor, can create the improved condensation and evaporation effects within the loop-heat-pipe (LHP) and thus, achieve significantly enhanced solar thermal and electrical efficiencies compared to traditional PV/T systems. Based on the results derived from our previous analytical study, a prototype MC-LHP-PV/T system employing R-134a as the working fluid was designed, constructed and tested, and the testing results were used to evaluate its operational performance including solar thermal and electrical efficiencies and their relevant impact factors. It is found that solar thermal efficiency of the MC-LHP-PV/T system varied with the inlet temperature and flow rate of coolant water, ambient temperature, as well as height difference between the condenser and evaporator. A lower inlet water temperature, a higher water flow rate, a higher ambient temperature, and a larger height difference between the condenser and the evaporator can help increase the solar thermal efficiency of the system. Under a range of testing conditions with the refrigerant charge ratio of 30%, a peak solar thermal efficiency (i.e., 71.67%) happened at solar radiation of 561W/m2, inlet water temperature of 18°C, water flow rate of 0.17m3/h, ambient temperature of 30°C, and height difference of 1.3m. This set of parametrical data is therefore regarded as the optimal operational condition of the MC-LHP-PV/T system. Under these specific operational condition and the real weather solar radiation, the solar thermal efficiency of the system was in the range 25.2% to 62.2%, while the solar electrical efficiency varied from 15.59% to 18.34%. Compared to the existing PV/T and BIPV/T systems, the new MC-LHP-PV/T system achieved 17.20% and 33.31% higher overall solar efficiency.
Hepatocellular carcinoma (HCC) remains one of the most common and lethal malignancies worldwide. Although DBF4-dependent kinase (DDK) complex composed of CDC7 kinase and its regulatory subunit DBF4 ...has been shown to be overexpressed in primary tumors and promotes tumor development, while its role and prognostic value in HCC remain largely unknown. In the present study, the expression of DBF4 and CDC7 and their relationship with clinical characteristics were comprehensively analyzed.
The mRNA expression profiles of HCC and the corresponding clinical data of HCC patients were downloaded from TCGA and GEO databases, respectively. The differences in DBF4 and CDC7 expression in tumor tissues and adjacent normal tissues were analyzed. HCC-derived tissue microarray (TMA) was used to evaluate and score the expression of CDC7 by immunohistochemistry (IHC) staining. The Kaplan-Meier method and the Cox regression method were used to analyze the relationship between overall survival and clinical characteristics of the patients. Gene set enrichment analysis (GSEA) was used to analyze the pathway enrichment of DBF4 and CDC7.
DBF4 and CDC7 had similar expression patterns in HCC patients. Detailly, compared with adjacent tissues, both mRNA and protein of DBF4 and CDC7 were significantly higher in HCC, and their expression was positively correlated with AJCC_T stage, clinical stage and G stage (grade) of liver cancer patients, and higher DBF4 or CDC7 expression predicted a worse prognosis in HCC patients with shorter overall survival (OS), recurrence-free survival (RFS), disease-specific survival (DSS) and progress-free survival (PFS). Cox regression analysis suggested that both DBF4 and CDC7 were independent risk factors for the prognosis of HCC patients in TCGA dataset. GSEA suggested that both DBF4 and CDC7 were positively correlated with cell cycle and DNA replication. Finally, the prognostic value of CDC7 was furtherly confirmed by TMA-based IHC staining results.
Our study showed that DDK complex was significantly increased in HCC. Both DBF4 and CDC7 may be potential diagnostic and prognostic markers for HCC, and high expression of DDK members predicts a worse prognosis in patients with HCC, which may be associated with high tumor cell proliferation rate.
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