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Pulse tube is one of the main parts of the pulse tube cryocooler. Ideally, the pulse tube works under adiabatic environment without heat transfer loss. But in real case, entropy is generated in the pulse tube itself from heat exchanged with the walls, turbulent mixing of the hot and cold gas segments, circulation of the gas within the tube, and end effect losses from the adiabatic to isothermal transition in the cycle. All these processes reduce the enthalpy flow in the pulse tube from the ideal acoustic power. However, no 1D model can sufficiently simulate these effects in the past. Also, most of the 1D models about the pulse tube part with a heat transfer coefficient is far from accurate, especially for micro pulse tube in which the heat transfer is more obvious. This work revealed that the basic heat transfer changes instantaneously and shows different tendencies in different time of one cycle, and no suitable law or explanation could fare well the phenomenon eventually. The phase angle changes from negative to positive that results in the relatively heat flux along the pulse tube becomes smaller, that could help the pulse tube to make a good performance.

The heat exchanger is an important component of pulse tube refrigerators (PTRs). The heat transfer in a cold heat exchanger under periodic unsteady flow is studied with the CFD method. The basic heat transfer mechanism has been explained, including the local heat transfer coefficient, heat flux, the temperature distribution of the narrow tube, and the relation between the Nusselt number and the Reynolds number. The regenerative effect of the cold heat exchanger of PTRs has been presented. The cold heat exchanger is cooled down by the low temperature gas due to the oscillating flow, and a temperature gradient is formed inside gradually. The regenerative effect will decrease the expansion work of the PTRs and lower the efficiency of the system, especially under bigger pressure ratio conditions.

Seeking active and low-cost cocatalysts is a vital task for solving the sluggish kinetics of photocatalysis process in environmental management. Herein, we report a novel and high-efficiency crystallized RuTe2 cocatalyst, and loaded it onto black TiO2 to form photocatalytic heterostructure (denoted as RuTe2/B-TiO2) for diclofenac (DCF) degradation. To the best of our knowledge, the RuTe2 as a cocatalyst for photocatalysis based on swift electron capture has not been documented yet. The degradation efficiency of DCF over 0.5% RuTe2/B-TiO2 reached 95.2% for 120 min, which is 1.2 times higher than that of pure B-TiO2. In addition, the effects of different calcination temperatures, catalyst amounts, DCF concentrations and solution pH of the as-prepared catalysts were also investigated in depth. Spectroscopy/electrochemistry showed that 0.5% RuTe2/B-TiO2 exhibited a narrower band gap, more active sites and better electrical conductivity than pure B-TiO2. Experiments with trapping agents have shown that •O2- was the main active substance under irradiation. Furthermore, intermediates for the photodegradation of DCF were detected by liquid chromatography mass system (LC-MS) and density functional theory (DFT) calculations. Finally, the degradation pathway was rationalized and a possible photocatalytic mechanism for 0.5% RuTe2/B-TiO2 was proposed.

The surface modification technology affects the friction and wear resistance of the piston/cylinder pair in axial piston pumps. However, in the early operating stages, the bearing surface cannot provide optimal load-bearing and lubrication conditions, resulting in a high wear rate and rapid loss of the surface modification layer. In this paper, the variation in wear of the piston/cylinder pair with the operating time is obtained by a wear degradation model. The wear contour at the lowest wear rate is derived to guide the design of a pre-machined surface contour. The experimental results show that the pre-machined contour reduces the wear rate during the initial operating stage, with the surface modification layer covering the pre-machined surface playing a greater role.

Bubble–particle interaction is a major focus for froth flotation research that has widespread use in mineral separation and concentration. The formation of a stable three phase contact (TPC) line is key to successful flotation. In industrial flotation processes, nearly all surfaces of particles are heterogeneous. Thus, the investigation of the influence of surface heterogeneity on the kinetics of TPC formation is important for understanding these processes. In this study, four types of heterogeneous surfaces were prepared by hydrophobization of glass slides followed by partial coverage with different mesh grids and oxidization with UV light. Interactions between bouncing bubbles and heterogeneous surfaces were investigated using a high-speed video camera. The results showed that the interval times between consecutive collisions with the patterned slide surface (before rupture) are almost independent of the surface. However, the behavior of the TPC line differed on various heterogeneous surfaces after bubble rupture. The terminal diameter was measured on different heterogeneous surfaces. It was found that the terminal diameter increased with the decrease in the mesh spacing of the grid. The slope of each curve is used to characterize the TPC line expansion velocity. The TPC line initial expansion velocity is inversely correlated with the grid mesh spacing. The surface heterogeneity had insignificant effect on the collision interaction between the bubble and the surface before the bubble rupture. However, after bubble rupture, the behavior of the expansion of TPC line was affected by the surface heterogeneity.

Understanding the effects of surface heterogeneities on wetting characteristics and contact line dynamics is significant for a number of applications. In this work, the advancing and receding contact angles on well-defined heterogeneous surfaces were measured using the captive bubble technique. Furthermore, contact line distortions were observed to clarify the origin of the changes in the contact angle. For heterogeneous surfaces with different hydrophilic area fractions but the same hydrophilic defect diameter, the defects had no restrictive effect on the retreating behavior of the contact line, resulting in a nearly constant advancing contact angle. Conversely, during receding contact angle measurements, the presence of a few hydrophilic defects caused three-phase contact line pinning. Increasing the number of hydrophilic defects led to more corrugations of the three-phase contact line, resulting in a decrease in the receding contact angle. For heterogeneous surfaces with the same hydrophilic area fraction but different hydrophilic defect diameters, the advancing contact angles were also nearly constant because in the hydrophilic region, no energy barrier prevented contact line movement. However, the greater energy barriers caused by larger hydrophilic defects led to a slight decrease in the receding contact angles. A comparison of the measured and calculated values for both the advancing and receding contact angles showed that the experimental contact angle results were consistent with the contact angles calculated using the line-fraction Cassie equation. These insights into the wetting behavior of heterogeneous surfaces under liquids are expected to lead to advanced practical applications of heterogeneous surfaces.

The wettability of solid surface is significant in a wide range of applications. The surface wettability would be affected by a number of factors, such as chemical composition, heterogeneity, surface roughness, and the properties of droplet/bubble. The variation of the contact angle with the size of bubble/droplet in a three phase contact system can be ascribed to the influence of the line tension. Understanding the evolution of contact angle and pseudo-line tension between a heterogeneous surface and bubble with different size is significant in guiding the applications of heterogeneous surfaces. In this work, heterogeneous surfaces with different hydrophobic area fractions were prepared. These surfaces consisted of discrete hydrophilic dots and interconnected hydrophobic background. The contact angles between the heterogeneous surface and bubble were measured at different bubble sizes and the pseudo-line tensions were calculated. Meanwhile, a model was developed to estimate the pseudo-line tension on the heterogeneous surface. The model predicted that the pseudo-line tension would increase with the increase of the hydrophobic area fraction and the vector would point to the liquid phase, which was consistent with the experimental results.

Abnormal O-linked N-acetylglucosamine (O-GlcNAc) concentrations have been associated with many diseases, but the lack of accurate detection method limited O-GlcNAc to be used as a biomarker in clinical diagnosis. Then O-GlcNAc transferase (OGT) has drawn researchers’ attention as it closed related to the level of O-GlcNAc and be considered to be a promising new target for diseases diagnosis. Nevertheless, the existing OGT detection methods are either need labeling or the sensitity can not meet the needs of clinic testing. Herein, a label-free and sensitive SPR biosensor was developed for accurate detection of OGT based on a multi-functional peptide. The designed peptide contains three recognition sites, one is the cleavage site of protease K, one is the O-GlcNAcylated site by OGT, and another is six histidine which be used as the signal report probe to recognize Ni2+. The immobilized peptide would be cleavaged by proteinase K, then the His-tag residue part will leave the surface of Au film, resulting less His-tag could bind to Ni2+ and a small SPR signal would be record. If the peptide is O-GlcNAcylated by OGT, the cleaving reaction would be limited due to the adjacent site of O-GlcNAcylation. Then more His-tag can be left on the Au film and a bigger SPR signal could be record, this signal is associated with the concentration of OGT. Utilizing the change of the peptide configuration as a signal report probe for OGT detection not only avoids labeling of peptide, but also makes the method more sensitive. The determination linear range of OGT is from 2.00 × 10−13 to 5.00 × 10−8 M with a detection limit of 1.19 × 10−13 M, and the separation of two enzyme reactions ensured the high selectivity of the method. Finally, the sensing system was successfully used for OGT detection in blood samples with satisfied recovery. In summary, the label-free SPR platform for accurate detection of OGT in real samples is helpful to promote OGT serve as a biomarker for early clinical diagnosis of O-GlcNAc related diseases.

Enantioselective separation of salbutamol enantiomers was carried out through the simultaneously synergistic extraction and stripping method with Ο,Ο-dibenzoyl-(2S,3S)-tartaric acid (+)-DBTA and di (2-ethylhexyl) phosphoric acid (D2EHPA) as chiral and non-chiral extractants, respectively. Chiral recognition mechanism of salbutamol enantiomers with (+)-DBTA was investigated using the Density Functional Theory (DFT) methods. The results showed that the chiral recognition in separation process was realized by the hydrogen-bond interaction. The binding energy of the complex resulting from (+)-DBTA and R-salbutamol was −86.14 kJ/mol, which was higher than that of the complex resulting from (+)-DBTA and S-salbutamol. The synergistic extraction experiment was preliminarily performed and the maximum separation factor was up to 1.65. Enantioseparation of salbutamol was conducted in the hollow fiber supported liquid membrane process. Various operating conditions, including the feed phase concentration, the component of membrane phase, the flow rate, and the pH of stripping side, were investigated. The results showed that the mass transfer resistance mainly focused on the membrane phase. The synergistic effect in liquid membrane system was also discussed. When the ratio of chiral to achiral extractant was 1.0:0.6, the separation factor was up to 2.0 in the stripping phase.

Using the step displacer in two stage pulse tube refrigerator has already been proved as a sufficient way to improve the efficiency. In this article, an experimental setup has been manufactured. A no-load temperature of 16.9 K is achieved with a step displacer type gas-coupled pulse tube refrigerator filled with stainless steel mesh. The influence of the connecting tube between pulse tube hot end and displacer on the performance of the refrigerator is investigated. The experimental results show that the phase shifting ability can be adjusted by the connecting tube. The performance of the refrigerator can be optimized by this method. For different rod diameters, there is an optimum connecting tube ratio to get the lowest temperature.

Closed intramedullary nailing is a classical therapeutic approach for floating knee injuries. An appropriate positioning is critical for a successful surgery. However, there is a lack of an ideal auxiliary device to facilitate the implantation of intramedullary nail. The authors developed a simple lower limb outrigger frame (SLLOF), which is made of nylon, to facilitate the nail implantation process. The SLLOF could be radiolucent and autoclavable. A total of 31 patients with floating knee injury underwent the closed intramedullary nailing assisted by SLLOF. The average operative duration was 91.0 min, and all tibial and femur fractures reached bony union. The SLLOF could assist well insertion of intramedullary nail for the treatment of floating knee injuries, with the advantages of simple operation, less manpower, easy imaging access but less radiation exposure, and more cost-effectiveness.