Background Seated workplaces have greatly increased in China. Many researchers have found that seated work is a risk factor in the development of low-back pain. Backrest can reduce the load on the ...lower back by transmitting more of the weight from the upper body to the floor via the backrest so as to prevent low-back pain. To design a suitable chair backrest for seated office work, some backrest parameters must be optimized. In this study, the role of backrest density on lumbar load and comfort were investigated. The goal of the study was to help establish criteria with which backrests that alleviate and prevent low back pain during seated office work can be designed and selected. Methods Twenty volunteers （10 men and 10 women） were seated in three backrest conditions （10 kg/m^3, 25 kg/m^3, and 40 kg/m^3）. Pressure data, including contact pressure （CP）, peak contact pressure （PCP） and contact area were collected during 15-minute trial. Subjective data were collected after each pressure test. Results Backrest density had a significant effect on backrest pressure variables. CP and PCP increased with increasing backrest density. Contact area decreased with increased density. In terms of user preference, the backrest with low density was most highly rated. Conclusions Backrest density plays an important role in lumbar load and comfort during seated work. During designing and selecting backrests, backrest density should be focused on so as to alleviate and prevent low-back pain during seated office work. Backrest density at 10 kg/m^3 got the lowest CP and PCP and largest contact area. Backrest with low density can reduce lumbar pressure and increase support contact area, which could raise comfort feeling. Backrest density at 10 kg/m^3 is better to maintain a balance between providing effective support and alleviating excess lordosis.
Upon heating and subsequent solvent displacement with pure water, the cold chitosan solution with aqueous alkaline/urea as solvent readily transforms into a hydrogel which is substantially stronger ...than traditional chitosan hydrogels regenerated from acidic solutions. In this work, we have systematically studied the effects of the treatment parameters in this two-step basic route and found that thermal gelation was the crucial step that dictated the structure and properties of the final gels. We hypothesized that the primary network formed in the thermal gelation step served as a template for the deposition of chitosan chains during solvent displacement, leading to a homogenous and compact structure. The primary network also provides crystalline seeds to facilitate the crystallization of the chitosan chains, leading to higher degree of crystallinity. This study provided a guideline for the preparation of chitosan hydrogels with high mechanical properties which is very meaningful to relevant research and applications.
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Differentiable ARchiTecture Search (DARTS) uses a continuous relaxation of network representation and dramatically accelerates Neural Architecture Search (NAS) by almost thousands of times in ...GPU-day. However, the searching process of DARTS is unstable, which suffers severe degradation when training epochs become large, thus limiting its application. In this article, we claim that this degradation issue is caused by the imbalanced norms between different nodes and the highly correlated outputs from various operations. We then propose an improved version of DARTS, namely iDARTS, to deal with the two problems. In the training phase, it introduces node normalization to maintain the norm balance. In the discretization phase, the continuous architecture is approximated based on the similarity between the outputs of the node and the decorrelated operations rather than the values of the architecture parameters. Extensive evaluation is conducted on CIFAR-10 and ImageNet, and the error rates of 2.25% and 24.7% are reported within 0.2 and 1.9 GPU-day for architecture search, respectively, which shows its effectiveness. Additional analysis also reveals that iDARTS has the advantage in robustness and generalization over other DARTS-based counterparts.
We assessed the effects of radiofrequency catheter ablation (RFCA) of the atrial epicardium on pacing-induced sustained atrial fibrillation (AF) and the expression and distribution of the ...intercellular gap junction protein connexin 43 (Cx43) in dogs.
In 12 mongrel dogs, after creation of complete AV block and implantation of a ventricular inhibited pacemaker, a high-rate pulse generator (20 to 30 Hz to induce AF) was implanted in the neck, connected to a right atrial endocardial pacing lead, and used to pace the atrium for 10 to 14 weeks. In group 1 (n=9 dogs), corrected sinus node recovery time (CSNRT), P-wave duration, 24-hour Holter ECG, maximal heart rate (MHR) in response to isoproterenol, and intrinsic heart rate (IHR) after atropine (0.04 mg/kg) and propranolol were measured before and after atrial pacing and RFCA. Group 2 dogs were used to assess the effect of chronic AF alone on Cx43 expression and distribution. All group 1 dogs developed sustained (>24 hours) AF. Right-sided RFCA of the atria eliminated the sustained AF in 5 dogs, but both right and left atrial RFCA was required to abolish sustained AF in the other 4 dogs. After RFCA restored sinus rhythm, CSNRT and P-wave duration were prolonged and MHR and IHR were decreased. Chronic rapid atrial pacing (group 2) increased the expression of Cx43, which was absent in ablated areas and markedly depressed in viable atrial myocytes near the ablation zones (group 1).
Rapid atrial pacing for long time periods induced sustained AF that can be eliminated by linear right and left atrial lesions created with RFCA, with preservation of sinus rhythm and atrial contractile function. Chronic AF increased the expression and distribution of gap junction protein Cx43, which became reduced in ablated and nearby nonablated areas.
With the emergence of digitalization technology, digital twin bridges the gap between physical and virtual worlds in industrial production with synchronization, reliability, and fidelity. The ...manufacturing process of complex products needs multiple working procedures, where novel industrial parts occur, causing scenes to be variable for robots to perceive and grasp. Due to the geometric difference among objects in various categories, it is significant to empower robotic systems with the capability of continuous learning for grasp detection in variable scenes. Therefore, a digital twin robotic system is proposed to realize bidirectional real-time data interaction and synchronization in the physical and virtual worlds. In this digital twin robotic system, a synthetic grasp detection dataset composed of industrial parts is built for an industrial grasping task. Besides, a novel deep learning method, adaptive spatial-awareness grasp network with a novel cc, is proposed to realize end-to-end 7-DoF grasp detection for industrial objects. In addition, a continuous learning strategy is proposed for 7-DoF grasp pose detection without catastrophic forgetting in variable scenes. Experiments in both virtual and physical worlds have demonstrated the effectiveness of our method for potential industrial implementation, and the average grasping success rate reaches 91% and 88% for novel objects in the virtual and physical worlds, respectively.
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Antimicrobial hydrogels have been proposed to be interesting materials used for wound healing due to their unique properties. Therefore, numerous scientists have made efforts to ...design and synthesize antibacterial hydrogels. At present, there are two commonly used methods for preparing antibacterial hydrogels. One is combining antibacterial agents with hydrogels. Antibacterial drugs include antibiotics, some biological extracts, natural polymers and some metal nanoparticles. In this review, physical combination (directly incorporating, swelling diffusion method, encapsulated in carriers) and chemical combination (hydrogels with inherent antibacterial activity, forming chemical bonds) are introduced depending on the methods and types of antibacterial agents incorporated with hydrogels. The other one is light-assisted antibacterial hydrogels, which involve photo-thermal antibacterial hydrogels and photo-dynamic antibacterial hydrogels. The common methods to prepare light-assisted antibacterial hydrogels are also described in this work. With the rapid improvements in antibacterial technology, many novel antibacterial hydrogels are constantly emerging. The most relevant studies and the latest status of research in this area were evaluated in this review.
The aim of the present study was to construct a fast-acting, eukaryotic expression vector in eukaryotic cells based on transmembrane-tumor necrosis factor‑α (TM‑TNF‑α) structure. Two types of ...recombinant eukaryotic expression vectors were constructed, pcDNA3.1-TM-enterokinase-TNF‑α and pcDNA3.1‑TM‑Factor Xa‑TNF‑α, according to the TNF‑α transmembrane segments. Following the generation of these vectors, mouse embryonic 3T3 fibroblasts were transfected and reverse transcription‑polymerase chain reaction and western blotting analyses were used to analyze mTNF‑α mRNA and protein expression levels, respectively, in total cellular protein extracts and extracellular fluid. The biological activity of TNF-α in the extracellular fluid was then measured using an MTT assay. The vectors were successfully constructed, and mRNA and fusion proteins were detected in the 3T3 cells. Among the fusion proteins, the one observed in pcDNA3.1-TM-FactorXa-TNF-α-transfected 3T3 cells remained as a transmembrane protein. In addition, treatment of L929 cells with TNF‑α derived extracellular fluid samples from pcDNA3.1‑TM‑FactorXa‑TNF‑α‑transfected 3T3 cells was associated with a dose‑dependent reduction in in cell‑specific activity. The results indicate that proteins expressed using pcDNA3.1‑TM‑FactorXa‑TNF‑α vectors form transmembrane proteins. In addition, the results indicate that, only when coupled with FactorXa activity, the extracellular region of TM‑TNF‑α forms s‑TNF‑α, and the controlled expression of the fusion protein is initiated.
Transcription factor activating enhancer binding protein 4 (TFAP4) is an important regulator in the genesis and progression of human cancers. Overexpression of TFAP4 has been found to be correlated ...with several malignancies. The present study assessed the clinical importance of TFAP4 in colorectal cancer (CRC). First, immunohistochemistry was used to analyze TFAP4 expression and the association of TFAP4 expression with clinicopathological features on a tissue microarray containing 208 CRC patients. The results revealed that TFAP4 protein expression was significantly upregulated in CRC tissues compared with that in normal colon tissues (P<0.001). Of note, statistical analysis revealed that TFAP4 expression was significantly correlated with a high pathological grade (P=0.034), advanced clinical stage (P=0.024), enhanced tumor invasion (P=0.002) and lymph node metastasis (P=0.041). In addition, the Cancer Genome Atlas dataset further validated that TFAP4 mRNA levels were increased in CRC with advanced clinical stage (P=0.026), lymph node metastasis (P=0.018) and vascular invasion (P=0.046). Kaplan-Meier survival analysis demonstrated that CRC patients with high TFAP4 expression had shorter overall survival compared with those with low TFAP4 expression (P=0.011). Importantly, overexpression of TFAP4 was a valuable independent prognostic factor for CRC patients (hazard ratio, 8.200; 95% confidence interval, 1.838-36.591; P=0.006). In summary, TFAP4 may have an important role in CRC progression and upregulation of TFAP4 may be a predictor of poor prognosis for CRC patients.
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