•l-Aspartate family amino acids (AFAAs) are important in human and animal diet.•Five-word strain breeding strategy “enter, flow, moderate, block, exit” are proposed.•Genetic modifications in central ...metabolic pathways for AFAAs production.•Metabolic pathways of AFAAs and derivatives and regulations involved.•Metabolic engineering in AFAAs metabolic pathways based on different strategies.
The l-aspartate amino acids (AFAAs) are constituted of l-aspartate, l-lysine, l-methionine, l-threonine and l-isoleucine. Except for l-aspartate, AFAAs are essential amino acids that cannot be synthesized by humans and most farm animals, and thus possess wide applications in food, animal feed, pharmaceutical and cosmetics industries. To date, a number of amino acids, including AFAAs have been industrially produced by microbial fermentation. However, the overall metabolic and regulatory mechanisms of the synthesis of AFAAs and the recent progress on strain construction have rarely been reviewed. Aiming to promote the establishment of strains of Corynebacterium glutamicum and Escherichia coli, the two industrial amino acids producing bacteria, that are capable of producing high titers of AFAAs and derivatives, this paper systematically summarizes the current progress on metabolic engineering manipulations in both central metabolic pathways and AFAA synthesis pathways based on the category of the five-word strain breeding strategies: enter, flow, moderate, block and exit.
The safety and efficacy of radical laparoscopic distal gastrectomy (LG) with D2 lymphadenectomy for the treatment of advanced gastric cancer (AGC) remain controversial. We conducted a randomized ...controlled trial to compare laparoscopic and conventional open distal gastrectomy with D2 lymph node dissections for AGC.
Between September 2012 and December 2014, 1,056 patients with clinical stage T2-4aN0-3M0 gastric cancer were eligible for inclusion. They were randomly assigned to either the LG with D2 lymphadenectomy group (n = 528) or the open gastrectomy (OG) with D2 lymphadenectomy group (n = 528). Fifteen experienced surgeons from 14 institutions in China participated in the study. The morbidity and mortality within 30 days after surgery between the LG (n = 519) and the OG (n = 520) groups were compared on the basis of the modified intention-to-treat principle. Postoperative complications were stratified according to the Clavien-Dindo classification.
The compliance rates of D2 lymphadenectomy were similar between the LG and OG groups (99.4% v 99.6%; P = .845). The postoperative morbidity was 15.2% in the LG group and 12.9% in OG group with no significant difference (difference, 2.3%; 95% CI, -1.9 to 6.6; P = .285). The mortality rate was 0.4% for the LG group and zero for the OG group (difference, 0.4%; 95% CI, -0.4 to 1.4; P = .249). The distribution of severity was similar between the two groups (P = .314).
Experienced surgeons can safely perform LG with D2 lymphadenectomy for AGC.
A general and efficient protocol was developed for the synthesis of polysubstituted pyridines from propargyl amines and unsaturated carbonyl compounds through a tandem condensation/alkyne ...isomerization/6π 3‐azatriene electrocyclization sequence. This process was found to be applicable to a wide range of readily available substrates (30 examples, up to 95 % yield) and could be readily performed on a preparative (20 g) scale. By taking advantage of this method for late‐stage pyridine incorporation, we successfully completed the collective total synthesis of suveoline, norsuveoline, and macrophylline.
6π to py: A wide range of polysubstituted pyridines were synthesized in a straightforward manner from propargyl amines and unsaturated aldehydes through a tandem condensation/alkyne isomerization/6π 3‐azatriene electrocyclization sequence in good yields. This transformation was used as a key step in the collective total synthesis of suveoline, norsuveoline, and macrophylline (see scheme).
An efficient strategy for the one-pot synthesis of polysubstituted pyridines via a cascade reaction from aldehydes, phosphorus ylides, and propargyl azide is reported. The reaction sequence involves ...a Wittig reaction, a Staudinger reaction, an aza-Wittig reaction, a 6π-3-azatriene electrocyclization, and a 1,3-H shift. This protocol provides quick access to the polysubstituted pyridines from readily available substrates in good to excellent yields.
Ocean current energy is the kinetic energy of seawater flow and is a low-cost, low-carbon, clean, and renewable energy source. Ocean current energy is mainly captured by the Ocean Current Turbine ...(OCT). However, as the depth of the water increases, the flow rate of the water decreases significantly. The main purpose of this paper is to study the low efficiency of current turbine capture due to low current velocities, with the main objective of achieving the effect of gathering and increasing the speed of low current energy. Firstly, this paper investigates the mechanism and mathematical model of the concentrated and accelerated flow of the diffuser shroud. Secondly, the velocity and pressure flow fields of the basic diffuser shroud are simulated and analyzed under different low flow velocity conditions (flow velocity below 1.0 m/s), different aspect ratios, and different diffusion opening angles. This paper further investigates the effect of speed increase for four different airfoil sections of diffuser shroud. Finally, measurements and verification are carried out with Particle Image Velocimetry (PIV) circular water hole experiments. The experimental results demonstrate the concentrated and accelerated results of the diffuser shroud. The basic diffuser shroud has a 39% increase in flow field velocity. The airfoil section diffuser shroud has a better velocity increase on the flow field than the basic diffuser shroud. The flow field flow rate increased to 58%. The optimum location for the speed increase is near the inlet and less than 0.5 times the inlet diameter. Compared to the simulation results, the experimental results of the PIV circulating water hole show an average error of less than 4%. The results of this paper provide a research basis for the efficient capture of current energy in deep-sea low-flow waters and a theoretical basis for the design of low-flow current energy turbines.
This study investigated the therapeutic effects of MSC-derived exosomes (MSC-Exos) on erectile function in a rat model of cavernous nerve injury (CNI).
MSCs were isolated from rat bone marrow and ...exosomes were isolated from the supernatants by ultracentrifugation. The tissue explant adherent method was used to isolate and culture corpus cavernosum smooth muscle cells (CCSMCs). MSCs and CCSMCs were identified by flow cytometry, in vitro differentiation or immunofluorescence staining. Thirty-two 10-week-old male Sprague Dawley (SD) rats were divided into four groups: a sham operation group and bilateral CNI groups that received intracavernosal (IC) injection of either PBS, MSCs or MSC-Exos. Four weeks after CNI and treatment, the erectile function of the rats was measured by electrically stimulating the cavernous nerve. The penile tissues were harvested for blinded histologic analysis and western blotting. H
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was used to induce apoptosis in the CCSMCs, and a flow cytometer was used to measure the cell viability of the CCSMCs treated with or without exosomes in vitro.
Recovery of erectile function was observed in the MSC-Exos group. The MSC-Exos treatment significantly enhanced smooth muscle content and neuronal nitric oxide synthase in the corpus cavernosum. The ratio of smooth muscle to collagen in the corpus cavernosum was significantly improved in the MSC-Exos treatment group compared to the PBS vehicle group. WB confirmed these biological changes. Cell viability of the CCSMCs was increased in the MSC-Exos-treated groups, and caspase-3 expression was decreased after the MSC-Exos treatment in vivo and in vitro.
Exosomes isolated from MSCs culture supernatants by ultracentrifugation could ameliorate CNI-induced ED in rats by inhibiting apoptosis in CCSMCs, with similar potency to that observed in the MSCs-treated group. Therefore, this cell-free therapy has great potential for application in the treatment of CNI-induced ED for replacing cell therapy. MSC-derived exosomes ameliorate erectile dysfunction in a rat model of cavernous nerve injury.
Additive manufacturing (AM) technologies can enable the direct fabrication of customized physical objects with complex shapes, based on computer-aided design models. This technology is changing the ...digital manufacturing industry and has become a subject of considerable interest in digital implant dentistry. Personalized dentistry implant treatments for individual patients can be achieved through Additive manufacturing. Herein, we review the applications of Additive manufacturing technologies in oral implantology, including implant surgery, and implant and restoration products, such as surgical guides for implantation, custom titanium meshes for bone augmentation, personalized or non-personalized dental implants, custom trays, implant casts, and implant-support frameworks, among others. In addition, this review also focuses on Additive manufacturing technologies commonly used in oral implantology. Stereolithography, digital light processing, and fused deposition modeling are often used to construct surgical guides and implant casts, whereas direct metal laser sintering, selective laser melting, and electron beam melting can be applied to fabricate dental implants, personalized titanium meshes, and denture frameworks. Moreover, it is sometimes required to combine Additive manufacturing technology with milling and other cutting and finishing techniques to ensure that the product is suitable for its final application.
Dental implants are widely used to restore missing teeth because of their stability and comfort characteristics. Peri-implant infection may lead to implant failure and other profound consequences. It ...is believed that peri-implantitis is closely related to the formation of biofilms, which are difficult to remove once formed. Therefore, endowing titanium implants with anti-adhesion properties is an effective method to prevent peri-implant infection. Moreover, anti-adhesion strategies for titanium implant surfaces are critical steps for resisting bacterial adherence. This article reviews the process of bacterial adhesion, the material properties that may affect the process, and the anti-adhesion strategies that have been proven effective and promising in practice. This article intends to be a reference for further improvement of the antibacterial adhesion strategy in clinical application and for related research on titanium implant surfaces.
The development of clean and environmentally friendly energy is necessary to address significant energy challenges, and abundant sea current energy, which plays a key role in the decarbonization of ...our energy systems and has attracted increasing attention among researchers. In the present study, a remote monitoring and diagnosis system was designed in accordance with the requirements of a 50 kW hydraulic transmission and control power generation system. Hardware selection and software function requirement analysis were then performed. The causes of system faults were analyzed, the output fault types of the improved model were determined, and effective monitoring parameters were selected. The accuracy of traditional spectra in diagnosing faults is poor; however, the generalization capability of support vector machines (SVM) is robust. Thus, an improved particle swarm algorithm optimized SVM fault diagnosis model for the hydraulic transmission control power generation system was proposed to rapidly and effectively determine the key parameters. Remote monitoring software for the hydraulic transmission and control power generation system was also developed. The results of remote monitoring and diagnostic tests showed that the software was able to satisfy the functional requirements of the hydraulic transmission control power generation remote monitoring system, and the operation effect was consistent with expectations. By comparing the test accuracy of different diagnostic models, the improved PSVM model has the highest test accuracy with a classification accuracy of 99.4% in the case of normal operation, accumulator failure, relief valve failure and motor failure. In addition, the proposed diagnostic method was effective, thereby ensuring safe and reliable operation of the hydraulic transmission control power generation system.
Accurate valve flow rate prediction is essential for the flow control process of independent metering (IM) hydraulic valve. Traditional estimation methods are difficult to meet the high-precision ...requirements under the restricted space of the valve. Thus data-based flow rate prediction method for IM valve has been proposed in this study. We took the four-spool IM valve as the research object, and carried out the IM valve experiments to generate labeled data. Picking up the post-valve pressure and valve opening as input, we developed and compared eight different data-based estimation models, including machine learning and deep learning. The results indicated that the SVR and DNN with three hidden layers performed better than others on the whole dataset in the trade-off of overfitting and precision. And MAPE of these two models was close to 4%. This study provides further guidelines on high-precision flow rate prediction of hydraulic valves, and has definite application value for development of digital and intelligent hydraulic systems in construction machinery.
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