To evaluate the effectiveness of limited internal fixation combined with a hinged external fixator in the treatment of peri-elbow bone infection.
The clinical data of 19 patients with peri-elbow bone ...infection treated with limited internal fixation combined with a hinged external fixator between May 2018 and May 2021 were retrospectively analyzed. There were 15 males and 4 females with an average age of 44.6 years (range, 28-61 years). There were 13 cases of distal humerus fractures and 6 cases of proximal ulna fractures. All the 19 cases were infected after internal fixation of fracture, and 2 cases were complicated with radial nerve injury. According to Cierny-Mader anatomical classification, 11 cases were type Ⅱ, 6 cases were type Ⅲ, and 2 cases were type Ⅳ. The duration of bone infection was 1-3 years. After primary debridement, the bone defect was (3.04±0.28) cm, and the antibiotic bone cement was implanted into the defect area, and the external fixator was installed; 3 cases were repaired with latissimu
The current COVID-19 pandemic, caused by SARS-CoV-2, poses a serious public health threat. Effective therapeutic and prophylactic treatments are urgently needed. Angiotensin-converting enzyme 2 ...(ACE2) is a functional receptor for SARS-CoV-2, which binds to the receptor binding domain (RBD) of SARS-CoV-2 spike protein. Here, we developed recombinant human ACE2-Fc fusion protein (hACE2-Fc) and a hACE2-Fc mutant with reduced catalytic activity. hACE2-Fc and the hACE2-Fc mutant both efficiently blocked entry of SARS-CoV-2, SARS-CoV, and HCoV-NL63 into hACE2-expressing cells and inhibited SARS-CoV-2 S protein-mediated cell-cell fusion. hACE2-Fc also neutralized various SARS-CoV-2 strains with enhanced infectivity including D614G and V367F mutations, as well as the emerging SARS-CoV-2 variants, B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.1 (Kappa), and B.1.617.2 (Delta), demonstrating its potent and broad-spectrum antiviral effects. In addition, hACE2-Fc proteins protected HBE from SARS-CoV-2 infection. Unlike RBD-targeting neutralizing antibodies, hACE2-Fc treatment did not induce the development of escape mutants. Furthermore, both prophylactic and therapeutic hACE2-Fc treatments effectively protected mice from SARS-CoV-2 infection, as determined by reduced viral replication, weight loss, histological changes, and inflammation in the lungs. The protection provided by hACE2 showed obvious dose-dependent efficacy in vivo. Pharmacokinetic data indicated that hACE2-Fc has a relative long half-life in vivo compared to soluble ACE2, which makes it an excellent candidate for prophylaxis and therapy for COVID-19 as well as for SARS-CoV and HCoV-NL63 infections.
Conveying and baling are two important links in the mechanized harvesting of ramie, in the face of ramie cutting and baling harvesting technology research gaps, low stalk conveying rate, high ...breaking rate and other problems. In this paper, according to the technical requirements of ramie harvesting, we designed a conveying and baling device, the hand-held ramie cutter. First, the key mechanism of the conveying and baling device of the equipment was designed. Then, we analyzed the location of stem clogging and the reasons for the breaking problem during the conveying and baling process. The field harvesting experiments were carried out according to the principles of Box–Behnken experimental design. Taking the machine travelling speed, conveying speed and ramie raking frequency as the test factors and using the Design-Expert V8.0.6.1 to process the data, we established a regression model for each experimental factor on the conveying rate and breaking rate. The order of influence of several factors on the breaking rate is: X2 > X1 > X3; and the effects of the three factors on the conveying rate were X3 > X2 > X1. Through response surface analysis (RSA), the effects of the factors on the indicators were explained, as was the impact of the factors on the indicators. Finally, the parameter optimization was carried out with the delivery rate as the core index. The best combination of motion parameters was obtained as follows: the travelling speed was 0.37 m/s, the chain conveying speed was 1.1 m/s, and the raking frequency was 144 times/min. With the combination of parameters under the field test verification, the results show that compared with the original work quality, the stalk delivery rate increased from 85.2% to 93% (an increase of 7.8%), the stalk breaking rate fell from 31.1% to 20.4% (a decrease of 10.7%). The performance of ramie harvesting and baling was greatly improved, and we achieved relatively satisfactory results.
Finite element numerical simulations provide a visual and quantitative approach to studying the interaction between rigid mechanical components and flexible agricultural crops. This method is an ...important tool for the design of modern agricultural production equipment. Obtaining accurate material model parameters for crops is a prerequisite for ensuring the reliability and accuracy of numerical simulations. To address the issue of unclear mechanical constitutive model parameters for industrial hemp stalks, this study utilized the theory of composite materials to establish a mechanical constitutive relationship model for industrial hemp stalks. Compression, tensile, and bending tests on different components of the stalk were conducted, using a computer-controlled universal testing machine, to obtain their elastic parameters. Combined with the measured basic material parameters and contact parameters of industrial hemp stalks, a finite-element numerical simulation model of industrial hemp stalks was established. By conducting Plackett–Burman and central composite experiments, it was determined that among the six measured parameters, the anisotropic plane Poisson’s ratio of the phloem and the isotropic plane Poisson’s ratio of the xylem have a significant influence on the maximum bending force of the stalk. Parameter optimization was carried out, using the relative error of the maximum bending force as the optimization objective, resulting in an anisotropic plane Poisson’s ratio of 0.054 for the phloem and an isotropic plane Poisson’s ratio of 0.28 for the xylem of industrial hemp stalks. To validate the accuracy and reliability of the optimized parameters, a numerical simulation was conducted and compared with the physical experiments. The simulated value obtained was 405.81 N while the actual measured value was 392.55 N. The error between the simulated and measured values was only 3.4%, confirming the effectiveness of the model. The precise parameters for the mechanical characteristics of industrial hemp stalk material obtained in this study can provide a parameter basis for future research on the numerical simulation of mechanized industrial hemp harvesting and retting.
In response to the unclear issue of whether the dynamic cutting performance and structural parameters of an industrial hemp blade, which was developed earlier based on the bionic prototype of the ...batocera horsfieldi, can be optimized in actual working conditions, this paper analyzes the effective clamping conditions of a reciprocating double-acting cutting blade for stalks and the cutting motion. To investigate the effect of different structural and motion parameters, as well as their interactions, of the bionic blade on cutting energy consumption, bionic blades with different combinations of tooth pitch and tooth angle were designed. A Box–Behnken response surface method with three factors and three levels was used to design an experimental scheme. Utilizing rigid-flexible coupling numerical simulation technology, numerical simulation experiments were conducted to investigate the cutting performance of industrial hemp stalks using the blade. A regression model for cutting energy consumption was established, and variance analysis indicated that tooth angle, speed ratio, and the interaction between tooth angle and speed ratio had an extremely significant effect on the regression model. The primary and secondary orders of factors affecting cutting energy consumption were determined to be: speed ratio > tooth angle > tooth pitch. Through optimization, the optimal parameter combination was found to be a blade tooth pitch of 6.61 mm, a tooth angle of 30°, and a speed ratio of 1.62. Under these conditions, the cutting energy consumption was 3947.99 mJ. The optimized parameters were verified through numerical simulation cutting experiments, and the results showed that the error compared with the optimization results was only 8.16%. This indicates that the optimization results have high credibility and further verifies the reliability of the model. This study can provide a reference for the development of cutting devices for industrial hemp harvesters and the selection of motion parameters.
Microbially induced carbonate precipitation (MICP) is a promising technology for solidifying sandy soil, ground improvement, repairing concrete cracks, and remediation of polluted land. By ...solidifying sand into soil capable of growing shrubs, MICP can facilitate peak and neutralization of CO2 emissions because each square meter of shrub can absorb 253.1 grams of CO2 per year. In this paper, based on the critical review of the microbial sources of solidified sandy soil, models used to predict the process of sand solidification and factors controlling the MICP process, current problems in microbial sand solidification are analyzed and future research directions, ideas and suggestions for the further study and application of MICP are provided. The following topics are considered worthy of study: (1) MICP methods for evenly distributing CaCO3 deposit; (2) minimizing NH4+ production during MICP; (3) mixed fermentation and interaction of internal and exogenous urea-producing bacteria; (4) MICP technology for field application under harsh conditions; (5) a hybrid solidification method by combining MICP with traditional sand barrier and chemical sand consolidation; and (6) numerical model to simulate the erosion resistance of sand treated by MICP.
The recent outbreaks of Zika virus (ZIKV) disease have caused worldwide concerns. Guangdong province is one of the commercial centers in China and communicates frequently with the epidemic areas. To ...date, 65.2% of the ZIKV infection cases in China were imported via port of entry in Guangdong. The continuous surveillance of imported cases is crucial for the prevention and control of potential ZIKV infection outbreak in China. In this study, a strain of ZIKV was isolated from the serum of a 6-year-old child returning from Venezuela. The morphology of the ZIKV was analyzed in vivo and in vitro by electron microscopy, and clusters of virus particles were found in the loose cytoplasmic membrane structures. The genomic sequence of the isolated ZIKV was determined, and the alignment and phylogenetic analysis identified one unique amino acid substitution occurring in the non-structural protein 4B (NS4B), and the isolated virus belonged to the Asian lineage.
Ramie is an important cash crop in China, and ramie fiber is an important raw material for the textile industry. As a shrub plant, the spatial distribution of the ramie plant is different from that ...of herbaceous crops, and its plant spacing and row spacing are not fixed, which affects the cutting operation during harvest. In order to solve the above problems, this study constructed a ramie spatial distribution model with statistical methods, and built a prediction model of ramie harvesting feeding quantity on this basis. Based on the analysis of the absolute motion trail of the ramie harvester cutting knife, the calculation equation of the missing cutting area was established, and then the prediction model of the mis-cutting rate was obtained. The results of the ramie field harvest showed that the prediction model of the feed quantity and mis-cutting rate was effective. These methods can provide references to the control and optimization of ramie harvester parameters.
Existing corn harvester cutting blades have problems associated with large cutting resistance, high energy consumption, and poor cut quality. Using bionics principles, a bionic blade was designed by ...extracting the cutting tooth profile curve of the B. horsfieldi palate. Using a double-blade cutting device testing system, a single stalk cutting performance contrast test for corn stalks obtained at harvest time was carried out. Results show that bionic blades have superior performance, demonstrated by strong cutting ability and good cut quality. Using statistical analysis of two groups of cutting test data, the average cutting force and cutting energy of bionic blades and ordinary blades were obtained as 480.24 N and 551.31 N and 3.91 J and 4.38 J, respectively. Average maximum cutting force and cutting energy consumption for the bionic blade were reduced by 12.89% and 10.73%, respectively. Variance analysis showed that both blade types had a significant effect on maximum cutting energy and cutting energy required to cut a corn stalk. This demonstrates that bionic blades have better cutting force and energy consumption reduction performance than ordinary blades.
Worldwide, public health systems are continually challenged by emerging and re-emerging viruses. It is therefore important that high-containment labs coordinate and communicate globally to share ...their experiences and lessons to improve their capacity to respond to threats. The National Biosafety (Level 4) Laboratory in Wuhan, CAS, which is the first Level 4 biosafety laboratory (BSL-4) in China, has been certified recently and it is expected to play an important role in the prevention and control of highly infectious agents in future. Trained and experienced staff in such organizations is the most important factor contributing to safety and security. Therefore, it is imperative to develop a standard training program. Accordingly, in the present study, we developed an improved training program and assessment system based on policies and practices developed by BSL-3/4s in other countries. It included the following three components: (1) A flexible modularized theoretical training: This training comprised 14 modularized theoretical topics such that staffs with different backgrounds could take this theoretical training with different topic combinations according to their knowledge and skill levels; (2) A standardized practical training assessment: This comprehensive assessment, which could be used with biosafety laboratory staff before, during, and after training, included standard operation procedures to meet the special requirements of trainees with different scores; and (3) An applicable documentation system: A certification system was established to evaluate the ability of all staff working inside or outside the laboratory, implemented by a special committee. This certification was approved and authorized by the director of the laboratory and was classified into three grades with corresponding minimal requirements. Further, the present study examined the importance of and need for networking for training BSL-3/4 staff. The establishment of rigorous standards for training BSL-3/4 staff will instill confidence in the public, policy makers, and security officials. Additionally, the expanded international network of BSL-3/4s will continue to be operated safely and will pose no risk to scientific staff, local communities, surrounding environment, and host nations. The clarification and coordination of training standards will help develop a highly-qualified biocontainment workforce and will result in a series of programs that will enable scientists to develop measures to deal with existing threat agents and new diseases that emerge.
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