Thermal performance and experimental analysis of stainless steel flat plate solar collector with full-flow channels.

The thermal performance of a flat plate solar collector (FPSC) is a critical indicator that depends on the environment, operational parameters, and dimensions. This study examines the impact of size on thermal performance improvement mechanisms. Firstly, numerical simulation models are introduced as the foundation for optimization research. This involves analyzing the flow resistance of microchannels and defining their structural parameters. Furthermore, experimental tests were conducted on a stainless steel flat plate solar collector (S/S FPSC) with the best design parameters to validate the accuracy of the mathematical model during the design phase. The results indicate that increasing the width of the microchannel and the height of corrugations can effectively enhance the thermal performance of the S/S FPSC. The momentary efficiency is projected to reach a remarkable 86.10% under ideal circumstances. Additionally, a mathematical expression was proposed to establish the relationship between the surrounding conditions and the momentary efficiency of the S/S FPSC. Moreover, the microchannel comprises S/S material, maintaining a homogeneous temperature distribution to maximize heat absorption. The use of stainless steel also extends the lifespan of the FPSC.

W-doped VO2 for high-performance aqueous Zn-ion batteries.

Aqueous Zn-ion batteries (AZIBs) have become one of the most promising energy storage devices due to their high safety and low cost. However, the development of stable cathodes with fast kinetics and high energy density is the key to achieving large-scale application of AZIBs. In this work, W-doped VO2 (W-VO2) is developed by a one-step hydrothermal method. Benefiting from the pre-insertion of W6+ and the introduction of the W-O bond, accomplishing an expanded lattice spacing and a stable structure, both improved kinetics and long cycle life are achieved. The W-VO2 delivers a specific capacity of 340.2 mA h g-1 at 0.2 A g-1, an excellent high-rate capability with a discharge capacity of 186.9 mA h g-1 at 10 A g-1, and long-term cycling stability with a capacity retention of 76.5% after 2000 cycles. The electrochemical performance of the W-VO2 has been greatly improved, compared with the pure VO2. The W doping strategy proposed here also presents an encouraging pathway for developing other high-energy and stable cathodes.

NiFe-LDH/MXene nano-array hybrid architecture for exceptional capacitive lithium storage.

Layered double hydroxides (LDHs) have great advantages in the domain of energy storage because of their exchangeable anions and large specific surface area. Nevertheless, the shortcomings of their poor electrical conductivity, easy stacking of nanosheets, and large volume variation in the cycling processes lead to unsatisfactory cycling stability and rate performance, which severely limits their further application. Therefore, we generated homogeneous nanoarrays of NiFe-LDH on the surface of Ti3C2Tx-MXene by a refluxing process. The resulting NiFe-LDH/MXene-500 hybrid material was applied as an anode of a lithium-ion battery (LIB) and exhibited a discharge capacity of 894.8 mA h g-1 at 200 mA g-1 (over 300 cycles) and could maintain a reversible capacity of 547.1 mA h g-1 even at 1 A g-1. With the addition of MXene, the volume increases of the NiFe-LDH/MXene hybrid materials were also significantly alleviated. The thickness of the NiFe-LDH/MXene-500 electrode only increased by 31% after 50 cycles, which was far better than the prepared NiFe-LDH electrode. On the hand, the synergistic interaction of NiFe-LDH and MXene could stabilize the structure, reduce the activation barrier of ion/electron diffusion, and promote electron transfer in the electrode. MXene with high conductivity can be used as electrical and ionic conductance media to promote the transformation reaction of NiFe-LDH. According to the detailed kinetic analysis, the capacitance control behavior is the main electrochemical reaction of NiFe-LDH/MXene electrodes.

A Cohort Study of Rivaroxaban Combined with D-Dimer Dynamic Monitoring in the Prevention of Deep Venous Thrombosis after Knee Arthroplasty.

Objective: To explore the cohort study of rivaroxaban combined with D-dimer dynamic monitoring in the prevention of deep venous thrombosis (DVT) after knee arthroplasty. Methods: Eighty-four patients with knee osteoarthritis who went through total knee arthroplasty from June 2019 to June 2021 in our hospital were arbitrarily assigned into the study group and the control group. The patients in the control group were cured with rivaroxaban anticoagulation after operation, and the study group was cured with dynamic monitoring of D-dimer on the basis of the control group. The incidence of postoperative DVT, pulmonary embolism (PE), and bleeding complications (incision ecchymosis and bleeding events) were compared. The related indexes such as drainage volume and blood transfusion volume were compared. The levels of activated partial prothrombin time (APPT), prothrombin time (PT), and D-dimer were dynamically monitored before and after operation. Visual analogue scale (VAS) was adopted to assess the degree of postoperative incision pain, the level of limb swelling before and after operation was measured, the circumference difference of affected limb was calculated, the ecchymosis area was assessed in the form of nine-palace grid, and the scores were compared. Results: According to the comparison of VAS score, there exhibited no remarkable difference before operation and on the first day after operation, but the VAS score decreased after operation, and the VAS score of the study group on the 3rd day, 7th day, and 14th day after operation was remarkably lower compared to the control group (P < 0.05). There exhibited no remarkable difference in drainage volume (P > 0.05), but the blood transfusion volume and total blood loss in the study group were remarkably lower (P < 0.05). There exhibited no remarkable difference in the level of PT on the 3rd day before operation and on the 3rd day after operation, but on the 7th day and 14th day after operation, the level of PT in the study group was remarkably higher (P < 0.05). The level of PT in the study group was remarkably higher (P < 0.05). There exhibited no remarkable difference in the level of APPT on the 3rd day before operation and on the 3rd day after operation, but on the 7th day and 14th day after operation, the level of APPT in the study group was remarkably higher (P < 0.05). The level of APPT in the study group was remarkably higher (P < 0.05). There exhibited no remarkable difference in the level of plasma D-dimer before operation (P > 0.05). The level of plasma D-dimer in the study group was lower (P < 0.05). In terms of the postoperative ecchymosis area score, the ecchymosis area score decreased remarkably after operation. Furthermore, the ecchymosis area score of the study group was remarkably lower (P < 0.05). In terms of the swelling degree of the affected limb, there exhibited no remarkable difference in thigh circumference and calf circumference before operation (P > 0.05), but after operation, the thigh circumference difference and calf circumference difference decreased, and the thigh circumference difference and calf circumference difference in the study group were lower (P < 0.05). The incidence of DVT in the study group was 16.67%, while that in the control group was 38.10%. No PE occurred in the two groups at the early stage after operation. There were 3 cases of incision ecchymosis, 1 case of bleeding event (incision oozing) in the study group, 11 cases of incisional ecchymosis, and 2 cases of bleeding event in the control group. In 3 patients with incisional bleeding, there were no obvious abnormalities in routine blood examination and blood coagulation indexes. The patients were given wound pressure bandaging and stopped using anticoagulants and changing wound dressings every day, all of which disappeared within 5 days. The incidence of early postoperative DVT and bleeding complications in the study group was lower (P < 0.05). Conclusion: Rivaroxaban combined with D-dimer dynamic monitoring has high clinical value in preventing DVT after knee arthroplasty and can effectively reduce the amount of blood loss during operation and the incidence of postoperative DVT, PE, and bleeding complications, which is worth popularizing to reduce the area of ecchymosis and the degree of pain after operation and shorten the recovery process.

Characteristic analysis of three-ecofriendly reduced graphene oxides (rGOs) and their application in water-ethanol-based fluids with different volume ratios.

In this paper, three-ecofriendly reduced graphene oxides (rGOs) were obtained by using three green reducing agents (beer, wine and cocoa) to reduce the graphene oxide (GO), and were labeled as B-rGO, W-rGO and C-rGO. Meanwhile, rGO nanofluids with different water-ethanol volume ratios (25 : 75, 50 : 50, 75 : 25) were prepared based on three-ecofriendly rGOs. The structure properties of the three-ecofriendly rGOs were investigated by XRD, FR-IT, Raman spectroscopy and XPS analysis. Meanwhile, the thermophysical properties of rGO nanofluids were analyzed. Experimental results indicated that the stability and thermophysical properties of rGO nanofluids were slightly different, indicating that the properties of the nanofluids are dependent on the type of base fluids and nanoparticles. When the water-ethanol volume ratio was maintained at 25 : 75, the stability experiment results showed that W-rGO nanofluids presented excellent stability, which indirectly confirmed their excellent thermal conductivity. Furthermore, the contact angle experiment indicated that the contact angles of rGO nanofluids decreased with the increase of temperature. In a word, these three rGOs and their nanofluids exhibited preferable properties that make them promising in the field of heat transfer.

Colorimetric detection of acetylcholinesterase and its inhibitor based on thiol-regulated oxidase-like activity of 2D palladium square nanoplates on reduced graphene oxide.

A convenient and sensitive colorimetric assay for acetylcholinesterase (AChE) and its inhibitor has been designed based on the oxidase-like activity of {100}-faceted Pd square nanoplates which are grown in situ on reduced graphene oxide (PdSP@rGO). PdSP@rGO can effectively catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) without the assistance of H2O2 to generate blue oxidized TMB (oxTMB) with a characteristic absorption peak at 652 nm. In the presence of AChE, acetylthiocholine (ATCh), a typical AChE substrate, is hydrolyzed to thiocholine (TCh). The generated TCh can effectively inhibit the PdSP@rGO-triggered chromogenic reaction of TMB via cheating with Pd, resulting in color fading and decrease in absorbance. Thus, a sensitive probe for AChE activity is constructed with a working range of 0.25-5 mU mL-1 and  a limit of detection (LOD) of 0.0625 mU mL-1. Furthermore, because of the inhibition effect of tacrine on AChE, tacrine is also detected through the colorimetric AChE assay system within the concentrations range 0.025-0.4 µM with a LOD of 0.00229 µM. Hence, a rapid and facile colorimetric procedure to sensitively detect AChE and its inhibitor can be anticipated through modulating the oxidase-like activity of PdSP@rGO. Colorimetric method for detection of AChE and its inhibitor is established by modulating the oxidase mimetic activity of {100}-faceted Pd square nanoplates on reduced graphene oxide (PdSP@rGO).

Study on organic-inorganic hybrid perovskite nanocrystals with regular morphologies and their effect on photoluminescence properties.

Organic-inorganic hybrid perovskite nanocrystals have been widely studied for their excellent photoelectric properties. However, the irregular morphologies of organic-inorganic hybrid perovskite nanocrystals have limited application in the field of lighting and display. From this, the regular morphologies of nanospheres, nanorods, nanoplatelets and MAPbBr3 (MA = CH3NH3 +) nanocrystals have been synthesized by regulating the type and proportion of auxiliary ligands. The phase evolution, morphology and fluorescent properties were systematically studied by the various instruments of XRD, TEM, PL/UV-vis spectroscopy and fluorescence decay analysis. With the morphologies changing from nanospheres to nanoplatelets, the emission peaks of MAPbBr3 nanocrystals red-shifted, and the lifetimes have increased gradually. The underlying mechanisms were thoroughly investigated and elucidated. On this basis, the role of acid and amine in the synthesis of MAPbBr3 nanocrystals was systematically studied by regulating the ratio of oleic acid and N-octylamine. The fluorescence kinetics of MAPbBr3 nanocrystals were studied by femtosecond transient absorption spectroscopy, and the charge carrier relaxation mechanism was clarified. Furthermore, the effect of temperature on the fluorescence properties of the nanocrystal was investigated in detail. Organic-inorganic hybrid perovskite nanocrystals with morphologies-controlled and excellent fluorescence properties are expected to be widely used in lighting and display fields.

Enhanced Dy3+ white emission via energy transfer in spherical (Lu,Gd)3Al5O12 garnet phosphors.

The Dy3+ doped (Lu,Gd)3Al5O12 garnet phosphors with spherical morphology were obtained via homogeneous precipitation method, followed by calcination at 1100 °C. The particle morphology does not change significantly, but can be controlled by adjusting the urea content. The synthesis, structure, luminescent properties of precursor and resultant particles were analyzed by the combined technologies of XRD, FE-SEM, PLE/PL decay behavior. The (Lu0.975Dy0.025)AG phosphors display strong blue and yellow emission at ~481 nm (4F9/2 → 6H15/2 transition of Dy3+) and ~582 nm 4F9/2 → 6H13/2 transition of Dy3+), respectively. The phosphors have similar color coordinate and temperature of (~0.33, ~0.34), ~5517 K, respectively, which are closed to the white emission. The particle size and luminescent intensity decreased while the lifetime increased with the urea concentration increasing. The Gd3+ addition does not alter the shape/position of emission peaks, but enhance the blue and yellow emission of Dy3+ owing to the efficient Gd3+ → Dy3+ energy transfer. The [(Lu1-xGdx)0.975Dy0.025]3Al5O12 phosphors are expected to be widely used in the lighting and display areas.