CoPS/Co4S3 Heterojunction with Highly Exposed Active Sites and Dual-site Synergy for Effective Hydrogen Evolution Reactions.

Cobalt phosphosulphide (CoPS) has recently been recognized as a potentially effective electrocatalyst for the hydrogen evolution reaction (HER). However, there have been no research on the design of CoPS-based heterojunctions to boost their HER performance. Herein, CoPS/Co4S3 heterojunction was prepared by phosphating treatment based on defect-rich flower-like Co1-xS precursors. The high specific surface area of nanopetals, together with the heterojunction structure with inhomogeneous strain, exposes more active sites in the catalyst. The electronic structure of the catalyst is reconfigured as a result of the interfacial interactions, which promote the catalyst's ability to adsorb hydrogen and conduct electricity. The synergistic effect of the Co and S dual-site further enhance the catalytic activity. The catalyst has overpotentials of 61 and 70 mV to attain a current density of 10 mA cm-2 in acidic and alkaline media, respectively, which renders it competitive with previously reported analogous catalysts. This work proposes an effective technique for constructing transition metal phosphosulfide heterojunctions, as well as the development of an efficient HER electrocatalyst.

Differences between native and prosthetic knees in terms of cross-sectional morphology of the femoral trochlea: a study based on three-dimensional models and virtual total knee arthroplasty.

BACKGROUND: The cross-sectional morphology of the prosthetic knee is crucial to understanding patellar motion and quadriceps strength after total knee arthroplasty. However, few comparative evaluations of the cross-sectional morphology of the femoral trochlea have been performed in the native knee and currently available femoral implants, and the relationship between the trochlear anatomy of prosthetic components and post-operative patellofemoral complications remains unclear. We aimed to investigate the differences in cross-sectional morphology of the femoral trochlea between native knees and prosthetic femoral components. METHODS: Virtual total knee arthroplasty was performed, whereby four different femoral components (medial-pivot, Triathlon, NRG and NexGen) were virtually superimposed onto three-dimensional models of 42 healthy femurs. The following morphological parameters were measured in three cross-sections (0, 45 and 90°) of the femoral trochlea: sulcus height, lateral tilt angle, medial tilt angle and sulcus angle. Only statistically significant differences are described further (p < 0.05). RESULTS: In the 0° cross-section, sulcus height was smaller in the native knee than in the Triathlon, NRG and NexGen components; all prosthetic components had smaller lateral tilt angles and larger medial tilt angles. In the 45° cross-section, sulcus height was larger in the native knee than in the medial-pivot, Triathlon and NexGen components; both lateral and medial tilt angles were smaller in the prosthetic components. In the 90° cross-section, sulcus height was smaller in the native knee than in the medial-pivot component; all prosthetic components had a larger lateral tilt angle and smaller medial tilt angle. In all cross-sections, the sulcus angle was smaller in the native knee. CONCLUSIONS: The discrepancy between native and prosthetic trochlear geometries suggests altered knee mechanics after total knee arthroplasty, but further cadaveric, computational or fluoroscopic investigations are necessary to clarify the implications of this observation. Our findings can be used to optimize biomechanical guidelines for total knee arthroplasty (patellar resurfacing or non-resurfacing) in Chinese individuals so as to decrease the risk of patellar lateral dislocation, to maintain stability and to optimize extensor kinematics.

Do size, shape, and alignment parameters of the femoral condyle affect the trochlear groove tracking? A morphometric study based on 3D- computed tomography models in Chinese people.

BACKGROUND: Our study aimed to investigate whether geometrical features (size, shape, or alignment parameters) of the femoral condyle affect the morphology of the trochlear groove. METHODS: Computed tomography models of 195 femurs (97 and 98 knees from male and female subjects, respectively) were reconstructed into three-dimensional models and categorised into four types of trochlear groove morphology based on the position of the turning point in relation to the mechanical axis (types 45°, 60°, 75°, and 90°). Only subjects with healthy knees were included, whereas individuals with previous knee trauma or knee pain, soft tissue injury, osteoarthritis, or other chronic diseases of the musculoskeletal system were excluded. The size parameters were: radius of the best-fit cylinder, anteroposterior dimension of the lateral condyles (AP), and distal mediolateral dimension (ML). The shape parameters were: aspect ratio (AP/ML), arc angle, and proximal- and distal- end angles. The alignment parameters were: knee valgus physiologic angle (KVPA), mechanical medial distal femoral angle (mMDFA), and hip-knee-ankle angle (HKA). All variables were measured in the femoral condyle models, and the means for each groove type were compared using one-way analysis of variance. RESULTS: No significant difference among groove types was observed regarding size parameters. There were significant differences when comparing type 45° with types 60°, 75°, and 90° regarding aspect ratio and distal-end angle (p < 0.05), but not regarding proximal-end angle. There were significant differences when comparing type 90° with types 45°, 60°, and 75° regarding KVPA, mMDFA, and HKA (p < 0.05). CONCLUSION: Among size, shape, and alignment parameters, the latter two exhibited partial influence on the morphology of the trochlear groove. Shape parameters affected the trochlear groove for trochlear type 45°, for which the femoral condyle was relatively flat, whereas alignment parameters affected the trochlear groove for trochlear type 90°, showing that knees in type 90° tend to be valgus. The morphometric analysis based on trochlear groove classification may be helpful for the future design of individualized prostheses.

Morphological classification of the femoral trochlear groove based on a quantitative measurement of computed tomographic models.

PURPOSE: This study aimed to investigate the natural morphology of the femoral trochlear groove based on quantitative measurement. METHODS: Computed tomographic femur models of 50 male and 50 female healthy Chinese adults (30-60 years) were analysed using three-dimensional software. Coaxial cutting planes (15° increments) rotating about the trochlear groove axis from the proximal to distal point were created, followed by the deepest point of the trochlear groove marked at each cross section. The shape, position, and orientation of the trochlear groove were analysed. RESULTS: The trochlear groove was located laterally relative to the mechanical axis and consisted of the laterally oriented proximal part and medially oriented distal part. Based on the turning points located on different cross sections, the trochlear groove was classified into four types: types 45°, 60°, 75°, and 90°. The mediolateral position relative to the mechanical axis was types 45°, 60°, 75°, and 90°, from the lateral to medial side, while the distal parts of them extended along the same path. The orientation of the trochlear groove was relatively consistent and smooth, which oriented at approximately 1° medially between two adjacent segments, except at approximately 10° medially at the turning point. CONCLUSION: The trochlear groove tracking varies greatly amongst a population that is mainly categorized into four types. This study may be helpful for better understanding of the natural trochlear groove anatomy, prosthetic design modification, and provide the reference value for studying patellofemoral diseases such as patellar maltracking and trochlear dysplasia. LEVEL OF EVIDENCE: Prospective study, Level II.

Morphological evaluation of the sagittal plane femoral load-bearing surface in computer-simulated virtual total knee arthroplasty implantation at different flexion angles.

PURPOSE: To examine the effect of implantation of the femoral component of a total knee arthroplasty (TKA) system in 0°, 3°, and 6° of flexion on the sagittal plane morphology of the femoral load-bearing surfaces. It was hypothesized that increasing the flexion angle would result in undersizing of the anterior surface without changing the flexion gap. METHODS: Computer simulation of a TKA using three-dimensional models of 10 healthy knees, matched to three different sized femoral components. Size discrepancy in the sagittal plane anterior, distal, and posterior joint surfaces between the native and prosthetic knees was calculated at 0°, 3°, and 6° of flexion. RESULTS: The required component size varied with the angle of implantation: 0°, size 3/size 4 (N = 7/3), 3°, size 3 (N = 10); and 6°, size 2/size 3 (N = 4/6). Component undersizing ranged between 4.4-6.3 mm at the anterior lateral surface, with a significant difference between 0° and 6° (p < 0.05), and 1.2-3.5 mm at the anterior medial surface. Component oversizing of the distal surface of the lateral condyle (2.9 mm) and undersizing of the medial surface of the posterior condyle (1.6-2.3 mm) were comparable at all three flexion angles of component implantation. CONCLUSIONS: Increasing the flexion angle of implantation increased the incidence of using a smaller size of femoral component without significant interference with the flexion gap. However, the effect of a smaller femoral component on undersizing of the anterior surface of the condyle and the impact on the extensor mechanism need to be considered.

Gene editing by SSB/CRISPR-Cas9 ribonucleoprotein in bacteria.

The application of CRISPR-Cas9 ribonucleoprotein (RNP) for gene editing is commonly used in plants and animals, but its application in bacteria has not been reported. In this study, we employed DNA single-strand binding protein (SSB) to construct an SSB/CRISPR-Cas9 RNP-editing system for non-homologous recombination and homologous recombination gene editing of the upp gene in bacteria. The RNP targeting the upp gene, along with SSB, was introduced into the protoplasts of Escherichia coli, Pseudomonas, and Bacillus subtilis. Transformants were obtained on plates containing 5-fluorouracil (5-FU) with gene editing efficiencies (percentage of transformants relative to the number of protoplasts) of 9.75 %, 5.02 %, and 8.37 %, respectively, and sequencing analysis confirmed 100 % non-homologous recombination. When RNP, SSB, and a 100-nucleotide single-stranded oligodeoxynucleotide (ssODN) donor were introduced into the protoplasts of these bacteria, transformants were obtained with editing efficiencies of 45.11 %, 30.13 %, and 27.18 %, respectively, and sequencing confirmed 100 % homologous recombination knockout of the upp gene. Additionally, introducing RNP, SSB, and a 100 base-pair double-stranded oligodeoxynucleotide (dsODN) donor containing a tetracycline resistance gene (tetR-dsODN) resulted in transformants on 5-FU plates with editing efficiencies of 35.94 %, 22.46 %, and 19.08 %, respectively, with sequencing confirming 100 % homologous recombination replacement of the upp gene with tetR. These results demonstrate that the SSB/CRISPR-Cas9 RNP system can efficiently, simply, and rapidly edit bacterial genomes without the need for plasmids. This study is the first to report the use of RNP-based gene editing in bacteria.

Comparison of Eco-friendly Ti-M Bimetallic Coordination Catalysts and Commercial Monometallic Sb- or Ti-Based Catalysts for the Synthesis of Poly(ethylene-co-isosorbide terephthalate).

Sustainable development greatly benefits from the effective synthesis of bio-based copolymers that are environmentally friendly. To enhance the polymerization reactivity for the production of poly(ethylene-co-isosorbide terephthalate) (PEIT), five highly active Ti-M (M = Mg, Zn, Al, Fe, and Cu) bimetallic coordination catalysts were designed. The catalytic activity of Ti-M bimetallic coordination catalysts and single Sb- or Ti-based catalysts was compared, and the effects of catalysts with a different type of coordination metal (Mg, Zn, Al, Fe, and Cu) on the thermodynamic and crystallization properties of copolyesters were explored. In polymerization, it was found that Ti-M bimetallic catalysts with 5 ppm (Ti) had higher catalytic activity than traditional antimony-based catalysts or Ti-based catalysts with 200 ppm (Sb) or 5 ppm (Ti). The Ti-Al coordination catalyst showed the best-improved reaction rate of isosorbide among the five transition metals used. Utilizing Ti-M bimetallic catalysts, a high-quality PEIT was successfully synthesized with the highest number-average molecular weight of 2.82 × 104 g/mol and the narrowest molecular weight distribution index of 1.43. The glass-transition temperature of PEIT reached 88.3 °C, allowing the copolyesters to be used in applications requiring a higher Tg, like hot filling. The crystallization kinetics of copolyesters prepared by some Ti-M catalysts was faster than that of copolyesters prepared by conventional titanium catalysts.

Non-isothermal crystallization kinetics and rheological behaviors of PBT/PET blends: effects of PET property and nano-silica content.

PBT and PET are subjected to thermal-oxidative degradation and thermomechanical degradation during the process of melt blending, which affect the polymer structure and properties. The effect of feed properties of PET and the addition of modified nanoparticles on blends are a question worthy of discussion. This work describes the melting and thermal stability, the crystallization behavior and non-isothermal crystallization kinetic, the rheological behaviors and mechanical properties of several PBT/PET blends prepared by twin-screw melt extrusion. Results show that the molecular chain of the polyester blends obtained by stable extrusion are not significantly degraded, there is only one obvious melting peak and crystallization peak on the thermal analysis curves, and the melting point is lower than either of the two polyesters. An appropriate amount of SD can effectively reduce the crystallization rate of the PBT material and extend the crystallization time. The rheological behavior of PBT/PET blends is complicated than PET raw materials and SD, as well as the melt processing temperature and shear rate will all affect the rheological behavior of the blends. For example, at low shear rate, polyester blends with SD exhibit strong shear thinning behavior. In general, the SD content affects the rheological property of blends in a way similar to the law of influence on crystallization behavior. When SD content is 0.3 wt%, a polyester product with higher elongation at break than pure PBT can be obtained. This can provide a useful reference for preparing commercialized polyester blend products with good melt processability and elongation by simple blending.

Recent Advances in the Seed-Directed Synthesis of Zeolites without Addition of Organic Templates.

Zeolites have been widely employed in fields of petroleum refining, fine chemicals and environmental protection, but their syntheses are always performed in the presence of organic templates, which have many drawbacks such as high cost and polluted wastes. In recent years, the seed-directed synthesis of zeolites has been paid much attention due to its low-cost and environmentally friendly features. In this review, the seed-directed synthesis of Al-rich zeolites with homonuclear and heteronuclear features, the seed-directed synthesis of Si-rich zeolites assisted with ethanol and the utility of seed-directed synthesis have been summarized. This review could help zeolite researchers understand the recent progress of seed-directed synthesis.

Crystallization and Thermal Behaviors of Poly(ethylene terephthalate)/Bisphenols Complexes through Melt Post-Polycondensation.

Three kinds of modified poly(ethylene terephthalate) (PET) were prepared by solution blending combined with melt post-polycondensation, using 4,4'-thiodiphenol (TDP), 4,4'-oxydiphenol (ODP) and hydroquinone (HQ) as the bisphenols, respectively. The effects of TDP, ODP and HQ on melt post-polycondensation process and crystallization kinetics, melting behaviors, crystallinity and thermal stability of PET/bisphenols complexes were investigated in detail. Excellent chain growth of PET could be achieved by addition of 1 wt% bisphenols, but intrinsic viscosity of modified PET decreased with further bisphenols content. Intermolecular hydrogen bonding between carbonyl groups of PET and hydroxyl groups of bisphenols were verified by Fourier transform infrared spectroscopy. Compare to pure PET, both the crystallization rate and melting temperatures of PET/bisphenols complexes were reduced obviously, suggesting an impeded crystallization and reduced lamellar thickness. Moreover, the structural difference between TDP, ODP and HQ played an important role on crystallization kinetics. It was proposed that the crystallization rate of TDP modified PET was reduced significantly due to the larger amount of rigid benzene ring and larger polarity than that of PET with ODP or HQ. X-ray diffraction results showed that the crystalline structure of PET did not change from the incorporation of bisphenols, but crystallinity of PET decreased with increasing bisphenols content. Thermal stability of modified PET declined slightly, which was hardly affected by the molecular structure of bisphenols.

Preparation and application of macromolecules with a fluorescence effect in polymer processing.

In this study, 9-anthracenemethyl methacrylate (AMMA) and styrene (St) as monomers and benzoyl peroxide as an initiator were used to synthesize P(St-co-AMMA), a macromolecule tracer with a fluorescence effect, via free radical copolymerization. A fluorescent online detection device was built on the basis of the principle of fluorescence online detection by using the single-screw extrusion platform of a torque rheometer to explore the effect of the amount of macromolecular tracer and screw speed on the residence time distribution of polystyrene in single-screw extrusion. Fourier transform infrared spectroscopy, 1H-NMR, thermal stability, fluorescence properties, and rheological properties show that the resulting product P(St-co-AMMA) has a degree of thermal stability, fluorescence, and rheological properties similar to polystyrene, so this product can be used to characterize the residence time distribution during single-screw extrusion. The amount of macromolecular tracer P(St-co-AMMA) does not affect the residence time distribution of polystyrene during single-screw extrusion processing, meanwhile, the minimum residence time decreases and the residence time distribution becomes narrow as the screw speed increases, that is, the axial mixing capacity of the single-screw extruder decreases as the screw speed increases.

An Investigation and Comparison of the Blending of LDPE and PP with Different Intrinsic Viscosities of PET.

The blending of aliphatic polyolefins and aromatic poly(ethylene terephthalate) (PET) based on different intrinsic viscosities (IV) was conducted in a torque rheometer. The comparison of blend components in terms of low density polythene (LDPE) and polypropylene (PP) in blending with PET was investigated, and the effects of the IV and proportion of PET on polymer blends are discussed in detail. Polymer blends with or without compatibilizer were examined by using a differential scanning calorimeter, thermogravimetric analyzer, rotary rheometer, field-emission scanning electron microscopy and a universal testing machine. It was found that the blending led to an increase in processability and a decrease in thermal stability for blends. The morphological analysis revealed that the incompatibility of blends was aggravated by a higher IV of PET, while this situation could be improved by the addition of compatibilizer. Results showed that there was an opposite effect for the tensile strength and the elongation at break of the polymer blend in the presence of a compatibilizer, wherein the influence of IV of PET was complicated.

Effect of Femoral Component Flexion Implantation on the Mediolateral Bone-prosthetic Fit in Total Knee Arthroplasty.

OBJECTIVE: Femoral component overhang in total knee arthroplasty (TKA) has been reported in previous studies. The purpose of this study was to evaluate the effect of femoral component flexion implantation on mediolateral bone-prosthetic fit in TKA. METHODS: Virtual prosthesis implantations were performed on computed tomographic models of 10 Chinese knees with femoral prostheses of the Advance Medial-Pivot knee system (MicroPort Orthopedics, Arlington, TN, USA), with the femoral component positioned at 0°, 3°, or 6° of flexion in the sagittal plane. For each degree of flexion implantation, the differences between the knee and femoral component models on the lateral and medial sides at trochlea (zone 1), anterior-distal condyle (zone 2), posterior-distal condyle (zone 3), and posterior condyle (zone 4) were measured. Positive difference values indicate component overhang, and negative difference values indicate component underhang. The values of component overhang (underhang) in each zone were statistically analyzed across the 3° of flexion implantation. RESULTS: With a greater degree of flexion implantation, overhang was reduced and even changed to underhang. With 0° of flexion implantation, an overhang exceeding 3 mm existed mainly on the medial side of zone 1 (5.81 mm) and the lateral side of zone 2 (3.39 mm). With 3° of flexion, overhang exceeding 3 mm was observed only on the medial side of zone 1 (3.10 mm), and underhang was observed only on the medial side of zone 4 (-0.32 mm). No overhang exceeding 3 mm was observed for 6° of flexion, while underhang was observed except on the lateral sides of zone 2 (1.32 mm) and zone 4 (1.10 mm) and on the medial side of zone 1 (1.54 mm). A significant difference in overhang values on the lateral and medial sides of zone 1 was observed between 0 and 6° of flexion (P < 0.05). CONCLUSION: The present study demonstrated that femoral component flexion implantation by 3° can reduce excessive overhang, although 3.10 mm of overhang remained at the medial side of zone 1. Conversely, 6° of flexion implantation can avoid 3 mm of overhang for any zone, but increases the risk of underhang. Slight flexion implantation may be an effective alternative technique to prevent excessive component overhang, especially in the trochlea and anterior region of the distal condyle, in Chinese patients with standard TKA prostheses.

[Clinical observation on therapeutic effect of the pressing plantar reflex area with wooden needle for treatment of patients with insomnia].

OBJECTIVE: To investigate the therapeutic effect of wooden needle on the patients with insomnia. METHODS: One hundred and twenty patients with insomnia were randomly divided into a wooden needle group and a western medicine group, 60 cases in each group. In the wooden needle group, the patients were treated with wooden needle to press the plantar reflex areas, such as cerebellar, throid and cerebral areas. In the western medicine group, Alprazolam was taken orally. Before and after treatment, Pittsburgh Sleep Quality Index (PSQI) was used to evaluate the therapeutic effect of both groups. RESULTS: The total therapeutic effect was 100.0% in the wooden needle group, while it was 90.7% in the western medicine group, there was no significant difference between the two groups (P > 0.05). Compared with PSQI before and after treatment, there was difference in the both groups (All P < 0.01), but there was no difference between the two groups (P > 0.05). CONCLUSION: The therapeutic effect of wooden needle is similar to that of Alprazolam on the insomnia, indicats that wooden needle is a better therapy for treating insomnia.