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Modular multilevel direct current transformer (MMDCT) provides a feasible solution to realize the efficient and stable integration of electric vehicle charging and discharging cluster into urban DC distribution network. However, there are impulse currents caused by capacitor charging and transformer inrush current in its starting process. Therefore, a fast pre-charging strategy based on compound frequency control was proposed. The independent control of direct current component and intermediate frequency component was used to realize simultaneous charging of the primary and secondary sides. The double closed-loop control was adopted in the primary side, while the variable-step phase shift peak current control was adopted in the secondary side, which solved the contradiction between charging speed and inrush current. Furthermore, a quantitative comparative analysis of various pre-charging strategies was carried out. The effectiveness and feasibility of the proposed pre-charging strategy were verified through simulation. The results show that the magnitude of the inrush current and the charging time are effectively controlled by the proposed method.

The "enclave economy" is an important governance tool for promoting regional integration. Guangdong Province occupies the leading position in exploring the "enclave economy" model in China, which has effectively promoted the development of the east and northwest of Guangdong Province through the "point to area" approach. However, certain problems that are associated with the "enclave economy" concept, including a weak level of industrial relatedness, disconnection with the development of the local urban system, and inadequate interest driving mechanisms, need to be urgently addressed. The article aims to explore the high-quality development path of the "enclave economy" in the new era, taking advantage of the symbiosis theory. Based on field research and semi-structured interview methods, the present study attempts to not only probe into the cooperative relationship and mutually beneficial symbiosis mechanism among different actors in the "enclave economy" but also explore a more sustainable and mutually beneficial development "enclave economy" model. With respect to theoretical contribution, based on the symbiosis theory and the characteristics of the "enclave economy", this study facilitates a better understanding of the high-quality development logic of the "enclave economy" from the perspective of symbiosis in particular and establishes a theoretical framework comprising the "industrial symbiosis network-industrial symbiosis unit-interest symbiosis mechanism" components. Empirically, this study takes the Guangqing Economic Cooperation Zone (Guangde Park) as the case study; reveals the development process and problems of the "enclave economy", including the isolation of industry transplantation, fragmentation of industry-city units, and locking of interests and mismatch between rights and responsibilities; and proposes high-quality development strategies, such as establishing a cross-regional "enclave economic circle", a resource-linking platform between industry and city, and a community of interests in industrial parks and towns, to form a more sustainable symmetric and mutually beneficial symbiotic mechanism. The key contribution of this study lies in the theoretical framework for the high-quality development of the "enclave economy" through the lens of symbiosis, which enriches the ways of analysis and cognitive logic of the "enclave economy" and advances cross-regional cooperation and "enclave economy" research. It enhances the cross-territorial geographic thinking of regional cooperation and "enclave economy" research, holding the potential to provide decision-making references for the promotion of regional coordinated development in Guangdong Province in the new period. It also has practical application value for relieving the pressure of unbalanced and insufficient regional development in China by promoting cross-municipal and cross-provincial cooperation.

[Objective] This study aimed to investigate the effects of uniconazole on physiological and biochemical properties of roots of different sweetpotato cultivars at seedling stage. [Method] Under hydroponic conditions in a greenhouse, the effects of exogenous uniconazole on physiological and biochemical properties of roots of different sweetpotato cultivars at seedling stage were analyzed under continuous drought stress simulated by PEG-6000. [Result] Compared with normal water supply treatment (N), drought treatment (D) decreased significantly root length, root surface area, average root diameter and root volume of Jishu 21 and Jihei 1; to be specific, compared with Jishu 21, root length, root surface area and average root diameter of Jihei 1 decreased greatly, but root volume of Jihei 1 decreased slightly. SOD, POD, APX activities and MDA content of Jishu 21 and Jihei 1 increased, and root vitality of two sweetpotato cultivars was reduced; to be specific, compared with Jihei 1, Jishu 21 exhibited significantly improved SOD, POD, APX activities, slightly improved MDA content and remarkably reduced root vitality. IAA, GAs and ZR contents of Jishu 21 and Jihei 1 declined at seedling stage; ABA content of two sweetpotato cultivars was improved; to be specific, compared with Jihei 1, IAA, GAs and ZR contents of Jishu 21 were reduced slightly, while ABA content of Jishu 21 was improved slightly. Under stress conditions, uniconazole treatment increased significantly root length and root surface area of Jihei 1 and increased slightly root volume of Jihei 1 compared with Jishu 21; uniconazole treatment increased significantly SOD, POD and APX activities and root vitality of Jihei 1 and declined remarkably MDA content of Jihei 1 compared with Jishu 21; uniconazole treatment increased significantly IAA, ZR and ABA contents of Jihei 1 compared with Jishu 21. [Conclusion] Drought-tolerant sweetpotato cultivar Jishu 21 exhibits high plasma membrane integrity and root vitality by increasing activities of antioxidant enzymes under drought stress and maintaining high contents of IAA, ZR and ABA. Unicona-zole exerts greater regulatory effects on physiological and biochemical properties of drought-sensitive sweetpotato cultivar Jihei 1 under drought stress. [ABSTRACT FROM AUTHOR]

Objective To explore the driving force of the oral astringency produced by the interaction of theaflavin (TF) and epigallocatechin-3-gallate (EGCG) to human salivary α-amylase(HSA). Methods The constants of the rate, equilibrium of reaction (ka, kd, KA, and KD) and Langmuir, Freundlich adsorption isotherm (KL, Kf, and Mm) were determined by surface plasmon resonance (SPR) technique and adsorption kinetics. Results Both of Langmuir and Freundlich models could be used for describing the binding processes of TF and EGCG onto HSA surfaces, and there were no significant differences of the correlation coefficient of determination between these two models (P > 0.05). The constants of adsorption isotherm, the rate and equilibrium constants of the association for TF were higher than those of EGCG (P < 0.05). The rate and equilibrium constants of the dissociation for TF were lower than those of EGCG (P < 0.05). The affinity of TF to HSA was higher than that of EGCG. Conclusion The sorely oral astringency is much easily produced by TF from the black tea rather than EGCG from the green tea. The driving force of the oral astringency is attributed to the hydrogen bonds of hydroxyl groups and hydrophobic interaction of galloyl groups in polyphenolic structures. [ABSTRACT FROM AUTHOR]

Background Benign prostatic hyperplasia (BPH) is a major cause of lower urinary tract symptoms in middle-aged and elderly men, while abnormal blood glucose can also lead to functional and organic changes in urinary system. However, there is still a lack of relevant research on the effect of abnormal blood glucose on urodynamic parameters of BPH patients. Objective To explore the impact of elevated fasting blood glucose (FBG) on urodynamic parameters of BPH patients. Methods The clinical data of 95 older male patients with BPH who were hospitalized in Department of Urology, Second Affiliated Hospital of Dalian Medical University from January to December, 2021 were analyzed retrospectively. They were divided into hyperglycemic group (n=11) and normal FBG group (n=84) according to the admission FBG level to compare clinical indicators. Results We found that the two groups had no statistically significant differences in average age, BMI, total prostate-specific antigen (tPSA), the volume, length, width and height of the prostate, and glycosylated hemoglobin (P>0.05). It was noticed that the mean course of diabetes in the hyperglycemic group was longer〔2 (0, 10) years vs 0 (0, 0) years, u=705.500, P=0.025〕. The average FBG level of the hyperglycemic group was significantly higher than that of the normal FBG group 〔 (8.9±2.1) mmol/L vs (5.4±0.7) mmol/L, t=-11.263, P0.05). However, the average scores on IPSS-storage〔 (13.7±1.4) scores vs (11.4±3.3) scores, t=-2.316, P=0.023〕 and bladder first sensation volume〔 (147.8±76.9) ml vs (100.2±48.0) ml, t=-2.532, P=0.014〕in the hyperglycemic group were significantly higher. Conclusion We demonstrated that elevated FBG has significant adverse effects on subjective and objective urodynamic parameters of BPH patients, which may lead to impaired first sensation volume of bladder and more severe storage symptoms. These patients often have a long course of diabetes, so more clinical attention should be given to their blood glucose control. It is of prominent significance to take active comprehensive intervention for symptomatic management of BPH.

There are a large number of pipelines/equipment and facilities need to be thermally insulated in the petroleum and petrochemical industry. However, in the practical operation, many problems may appear in the thermal insulation structures, such as thermal insulation structure failure and corrosion under the thermal insulation which could bring safety risks to the production. In this work, the causes and evaluation methods of thermal insulation structure failure as well as the life evaluation mehtods of thermal insulation structure in the above - mentioned industry were summarized. Meanwhile, the detection method of corrosion under the thermal insulation layer in such industry as well as some corresponding anticorrosion methods were reviewed, with the expectation of providing certain guidance for solving the corrosion problem under the thermal insulation layer in the petroleum and petrochemical industry.

The 2019 novel coronavirus(SARS-CoV-2) belongs to β coronavirus and is the seventh one to be found as pathogen of humans in Wuhan by the end of 2019. Clinical statistics shows that the virus often leads to myocardial injury, and patients with underlying cardiovascular diseases have a higher risk of infection and worse prognosis. The mechanism of the virus on myocardial injury is still unknown. This paper discusses the role of SARS-CoV-2 in myocardial damage with regard to immune system.

To deal with nonlinear characteristics of spectra data for the thermal power plant flue, a nonlinear partial least square (PLS) analysis method with internal model based on neural network is adopted in the paper. The latent variables of the independent variables and the dependent variables are extracted by PLS regression firstly, and then they are used as the inputs and outputs of neural network respectively to build the nonlinear internal model by train process. For spectra data of flue gases of the thermal power plant, PLS, the nonlinear PLS with the internal model of back propagation neural network (BP-NPLS), the non-linear PLS with the internal model of radial basis function neural network (RBF-NPLS) and the nonlinear PLS with the internal model of adaptive fuzzy inference system (ANFIS-NPLS) are compared. The root mean square error of prediction (RMSEP) of sulfur dioxide of BP-NPLS, RBF-NPLS and ANFIS-NPLS are reduced by 16.96%, 16.60% and 19.55% than that of PLS, respectively. The RMSEP of nitric oxide of BP-NPLS, RBF-NPLS and ANFIS-NPLS are reduced by 8.60%, 8.47% and 10.09% than that of PLS, respectively. The RMSEP of nitrogen dioxide of BP-NPLS, RBF-NPLS and ANFIS-NPLS are reduced by 2.11%, 3.91% and 3.97% than that of PLS, respectively. Experimental results show that the nonlinear PLS is more suitable for the quantitative analysis of glue gas than PLS. Moreover, by using neural network function which can realize high approximation of nonlinear characteristics, the nonlinear partial least squares method with internal model mentioned in this paper have well predictive capabilities and robustness, and could deal with the limitations of nonlinear partial least squares method with other internal model such as polynomial and spline functions themselves under a certain extent. ANFIS-NPLS has the best performance with the internal model of adaptive fuzzy inference system having ability to learn more and reduce the residuals effectively. Hence, ANFIS-NPLS is an accurate and useful quantitative thermal power plant flue gas analysis method.

Objective: To establish HPLC fingerprint of Prunella vulgaris and provide evidence for quality control and identification of the Chinese crude drug., Methods: The HPLC method was used, chromatography conditions were Agilent Eclipse XDB-C18 (4.6 mm x 250 mm, 5 microm) column with gradient mobile phase of acetonitrile-0.1% acetic acid, UV detection wavelength was 290 nm and the column temperature was 30 degrees C with the flow rate of 1.0 mL/min, the sample injection was 10 microL., Results: HPLC fingerprints of 19 samples of Prunella vulgaris were established. 14 common peaks were selected as the fingerprint peaks in all samples. Among the obtained fingerprints, most of the detected peaks were separated effectively. 19 samples had high similarities., Conclusion: The established HPLC fingerprint has desirable accuracy, repeatability and stability, which can be used for one of the quality control methods of Prunella vulgaris.

Objective: To evaluate the thickness and viscoelasticity of whole saliva (WS), parotid saliva (PS) and submandibular/sublingual gland saliva (SMSLS) film adsorption on the hydroxyapatite (HA) surface., Methods: Ultra-thin layer of HA nanocrystals was coated on the dissipation TiO(2) sensor of gold quartz crystal microbalance using electrophoretic deposition technique. The thickness of the HA layer was measured by the ellipsometer, and element analysis was conducted using X-ray photoelectron spectroscopy. Atomic force microscopy and scanning electron microscope were used to observe its morphology. The in-situ adsorption thickness, the shear elastic modulus and the shear viscosity of salivary layers (WS, PS and SMSLS) on HA surfaces were investigated. The statistical data were analysed by an one-way ANOVA analysis followed by a SNK-q test., Results: The results show that the HA layer was a plate-like morphology with 1.53 ± 0.12 in Ca/P molar ratio, (19.1 ± 0.9) nm in the thickness and (6.5 ± 1.6) nm in the roughness. The thickness of salivary film was SMSLS [(21.84 ± 1.25) nm] > WS[(17.91 ± 1.35) nm] > PS [(14.30 ± 1.03 nm) (P < 0.05). The shear elastic modulus of salivary film was PS [(0.61 ± 0.01) MPa] > SMSLS [(0.31 ± 0.09) MPa] and WS [(0.25 ± 0.03) MPa] (P < 0.05). The trend of the shear viscosity was opposite to one of thickness., Conclusions: The characteristics of saliva adsorption on HA surface suggest that the thicker, softer and more hydrated properties for the SMSLS and WS films are likely to afford a stronger lubrication to protect oral surfaces from wear and dehydration. The viscoelasticity of the PS film is probably related to the retention covering the oral cavity.

Objective: To explore the driving force of the oral astringency produced by the interaction of theaflavin (TF) and epigallocatechin-3-gallate (EGCG) to human salivary a-amylase(HSA)., Methods: The constants of the rate, equilibrium of reaction (k(a), k(d), K(A), and K(D)) and Langmuir, Freundlich adsorption isotherm (K(L), K(f), and Mm) were determined by surface plasmon resonance (SPR) technique and adsorption kinetics., Results: Both of Langmuir and Freundlich models could be used for describing the binding processes of TF and EGCG onto HSA surfaces, and there were no significant differences of the correlation coefficient of determination between these two models (P > 0.05). The constants of adsorption isotherm, the rate and equilibrium constants of the association for TF were higher than those of EGCG (P < 0.05). The rate and equilibrium constants of the dissociation for TF were lower than those of EGCG (P < 0.05). The affinity of TF to HSA was higher than that of EGCG., Conclusion: The sorely oral astringency is much easily produced by TF from the black tea rather than EGCG from the green tea. The driving force of the oral astringency is attributed to the hydrogen bonds of hydroxyl groups and hydrophobic interaction of galloyl groups in polyphenolic structures.

Objective: The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine., Methods: Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS)., Results: When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time., Conclusion: The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.

Objective: To compare the osseointegration and corrosion of different kind of coatings on pure titanium., Methods: By plasma spraying technology, nitrogen silicon zirconium-hydroxylapatite (ZrSiN-HA) compound coating was prepared on the surface of pure titanium and the pure titanium was implanted with the mandible of the experimental animal. The superficial appearance of the compound coating was observed and analyzed by scanning electron microscope (SEM). The ZrSiN-HA, nitrogen silicon zirconium (ZrSiN), hydroxylapatite (HA) and pure titanium were compared and examined. In the four groups, the bone binding force of coatings were detected, and the superficial appearance of the break regions were observed by the electronic multipurpose material testing aircraft. In the four groups, the anticorrosive of coatings were compared and examined on the electrochemistry corrosion testing system., Results: Experimental results indicated that the implant surface sprayed with the ZrSiN-HA was more compact than that sprayed with HA. The crystallization was obvious. Compared with the other coatings, the bone binding force of the ZrSiN-HA coating was the highest, and its anticorrosive performance was the strongest., Conclusion: The application of ZrSiN-HA coating is advantageous to the long-term retention of implant, and it has huge latent application value to dental dummy.

Objective: To measure the translucency parameter (TP), masking effect (ME), and contrast ratio (CR) of opal porcelain of Ceramco, Shofu, Noritake, and Vita, and to compare the correlations among the three transmission parameters, in order to provide reference for selecting opal porcelain correctly., Methods: The color of specimens was measured according to CIE L*a*b* under different background and reflectance mode with a Color-Eye 7000A spectrophotometer. The color difference, TP, and ME value were calculated. Within 400-750 nm spectra, the ratio of light reflectance was measured, and CR was also calculated. The data was compared by ANOVA and SNK-q test (alpha=0.05). The correlation and multiple linear regression between TP, CR, and ME were analyzed (alpha=0.05)., Results: There were statistical difference with different shade of the same brands (P<0.05). The correlations between ME and TP, TP and CR, ME and CR were existed (P<0.05). TP was correlated not only with ME but also with CR based on multiple regression analysis (P<0.05). The partial correlation coefficients were statistically significant (P<0.05). CR was the main devotion to translucency parameter on multiple regressions., Conclusion: It is recommended to select opal porcelains based on transmission parameters. CR value has an inner significance of opaque property of opal porcelain and can express opacity property of opal porcelain more appropriately than ME.

Objective: The aim of this investigation was to examine the changes of the color stability, surface microstructure and chemical constitution of light-curing composite resin after accelerated aging, and the relations between them., Methods: Four light-curing composite resin were aged in an accelerated aging instrument. The color was measured by CIE L*a*b* with a spectrophotometer after treatment for 24 h and 96 h. And the color differences were calculated. Environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) spectrometer were used to examine the microstructure and chemical composition of the specimens before and after accelerated aging. The color differences were analyzed statistically by repeated-measures two-way analysis of variance and t-test after aging for 24 h and 96 h. The level of significance was defined as alpha=0.05., Results: The materials demonstrated statistically significant differences in color after aging between the 24 h and 96 h (P<0.05). There were significant influences on the microstructure and the chemical composition after aging. The matrix appeared some concaves and pores, the filler particles exposed after aging. The energy of chemical bonds were weaken or broken under the aging, and the unsaturated polymer reacted again., Conclusion: The color differences of the composite resin increase with the aging time and irradiation dose. The hybrid filled composites have the best color stability.

Self-assembled InAs quantum dots were prepared on GaAs(100) substrate in a solid source molecular beam epitaxy system. The distribution and topographic images of uncapped dots were studied by atomic force microscope. The statistical result shows that the quantum dots are bimodal distribution. The photoluminescence spectrum results shows that the intensity of small size quantum dots dominated, which may be due to: (1) the state density of large quantum dots lower than that of small quantum dots; (2) the carriers capture rate of large size quantum dots is small relative to that of small ones; (3) there is a large strain barrier between large quantum dots and capping layer, and the large strain is likely to produce the defect and dislocation, resulting in a probability of carriers transferring from large quantum dots to small dots that is very small with temperature increasing.

Objective: To evaluate the matching of the shade between beverage and modifying porcelain shade guide according to Munsell color order system, thus to provide the reference basis for selecting modifying porcelain to mimic the stain of natural tooth by technician., Methods: The shade of Vita Akzent, Vita Interno, Shofu Vintage & Unibond and Noritake Super Porcelain EX-3 shade tabs as well as 15 kinds of beverage were measured according to Munsell color order system on Color-Eye 7000A spectrophotometer. The difference of the frequency of approximate hue, value, and chroma between shade tabs and beverage were compared by calculating the Fisher exact probabilities., Results: The frequency of approximate hue between 4 kinds of shade tabs and 15 kinds of bev-erage was significant different (P<0.05), while the frequency of approximate value, and chroma was not significant different (P>0.05)., Conclusion: Except the hue, the color distribution of 4 kinds of shade tabs was similar to that of 15 kinds of beverage. But the color of beverage also can be approximately matched by any kind of modifying porcelain by mixing porcelain powder of appropriate hue, value, and chroma.