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OBJECTIVE: To investigate the effect of the sequence of intermediate instrumentation with long screws and distraction-reduction on mild to moderate thoracolumbar fractures treated by posterior open and short-segmental fixation. METHODS: The clinical data of 68 patients with mild to moderate thoracolumbar burst fractures who met the selection criteria between January 2016 and June 2019 were retrospectively analyzed. The patients were divided into group ISDRF (intermediate screws then distraction-reduction fixation, 32 cases) and group DRISF (distraction-reduction then intermediate screws fixation, 36 cases) according to the different operation methods. There was no significant difference between the two groups in age, gender, body mass index, fracture segment, cause of injury, and preoperative load-sharing classification score, thoracolumbar injury classification and severity score, vertebral canal occupational rate, back pain visual analogue scale (VAS) score, anterior height of fractured vertebra, and Cobb angle (P>0.05). The operation time, intraoperative blood loss, complications, and fracture healing time were recorded and compared between the two groups. The vertebral canal occupational rate, anterior height of fractured vertebra, kyphosis Cobb angle, and back pain VAS score before and after operation were used to evaluate the effectiveness. RESULTS: There was no significant difference in intraoperative blood loss and operation time between the two groups (P>0.05). No vascular or spinal nerve injury and deep infections or skin infections occurred in both groups. At 1 week after operation, the vertebral canal occupational rate in the two groups was significantly improved when compared with that before operation (P0.05). The patients in both groups were followed up 18-24 months, with an average of 22.3 months. All vertebral fractures reached bone union at 6 months postoperatively. At last follow-up, there was no internal fixation failures such as broken screws, broken rods or loose screws, but there were 2 cases of mild back pain in the ISDRF group. The intra-group comparison showed that the back pain VAS score, the anterior height of fractured vertebra, and the Cobb angle of the two groups were significantly improved at each time point postoperatively (P0.05). The comparison between groups showed that there was no significant difference in the remission rate of VAS score between the two groups at 1 week postoperatively (P>0.05), the recovery value of the anterior height of fractured vertebra in ISDRF group was significantly higher than that in DRISF group (P0.05). CONCLUSION: In the treatment of mild to moderate thoracolumbar burst fractures with posterior short-segment fixation, the instrumentation of long screws in the injured vertebrae does not affect the reduction of the fracture fragments in the spinal canal. DRISF can better maintain the restored anterior height of the fractured vertebra and reduce the loss of kyphosis Cobb angle during the follow-up, indicating a better long-term effectiveness.

OBJECTIVE: To explore the clinical characteristics and surgical treatment strategies of delayed spinal cord injury (SCI) caused by atypical compression of old thoracolumbar fracture. METHODS: Between January 2011 and June 2018, 32 patients with delayed SCI caused by atypical compression of old thoracolumbar fracture who met the inclusion criteria were admitted and divided into group A (20 cases, underwent anterior subtotal vertebral body resection+titanium mesh reconstruction+screw rod internal fixation) and group B (12 cases, underwent posterior 270° ring decompression of vertebral canal+titanium mesh reconstruction+screw rod internal fixation) according to the different operation approaches. There was no significant difference between the two groups in age, gender, cause of injury, fracture segment, disease duration, preoperative American Spinal Injury Association (ASIA) classification, and preoperative back pain visual analogue scale (VAS) score, lumbar Japanese Orthopaedic Association (JOA) score, kyphosis angle, and vertebral canal occupational ratio (P>0.05). The incision length, operation time, intraoperative blood loss, complications, and bone fusion time of reconstructed vertebrae were recorded and compared between the two groups; the kyphosis angle, back pain VAS score, and lumbar JOA score were used to evaluate the effectiveness. RESULTS: Except that the incision length in group A was significantly shorter than that in group B (t=−4.865, P=0.000), there was no significant difference in intraoperative blood loss and operation time between the two groups (P>0.05). There was no deaths or postoperative paraplegia cases in the two groups, and no deep infection or skin infection occurred. There was 1 case of cerebrospinal fluid leakage, 1 case of inferior vena cava injury, and 1 case of chyle leakage in group A. No serious complications occurred in group B. There was no significant difference in the incidence of complications between the two groups (P=0.274). All 32 patients were followed up 12-61 months, with an average of 20.8 months. The follow-up time for groups A and B were (19.35±5.30) months and (23.25±12.20) months respectively, and the difference was not significant (t=−1.255, P=0.219). The reconstructed vertebrae in all cases obtained bony fusion postoperatively. The fusion time of groups A and B were (8.85±2.27) months and (8.50±2.50) months respectively, and the difference was not significant (t=0.406, P=0.688). The kyphosis angle, back pain VAS score, and lumbar JOA score of the two groups at each time point after operation and last follow-up were significantly improved when compared with preoperatively (P0.05). Comparison of kyphosis angle, back pain VAS score, and lumbar JOA score between the two groups at various time points postoperatively showed no significant difference (P>0.05). At last follow-up, the JOA score improvement rate in groups A and B were 83.87%±0.20% and 84.50%±0.14%, respectively, and the difference was not significant (t=–0.109, P=0.914); the surgical treatment effects of the two groups were judged to be significant. CONCLUSION: In the later stage of treatment of old thoracolumbar fractures, even mild kyphosis and spinal canal occupying may induce delayed SCI. Surgical correction and decompression can significantly promote the recovery of damaged spinal cord function. Compared with anterior approach surgery, posterior approach surgery has the advantages of less trauma, convenient operation, and fewer complications, so it can be preferred.

According to different clamping methods, nine modes (C_MODE1-9) of the traditional discontinuous pulsewidth modulation (DPWM) for neutral-point-clamped three-level converter have been revealed. Since traditional DPWM cannot balance neutral point (NP) voltage under the full range of modulation index (MI) and power factor (PF), two extended modes (E _MODEs) are proposed in this paper, which can balance NP voltage. The proposed extended discontinuous pulsewidth modulation (EDPWM) is characterized by using C_MODEs and E_MODEs alternately.Therefore, EDPWM can balance NP voltage under the full range of MI and PF. Since the switching numbers under C_MODE and E_MODE in one switching cycle are two and three, respectively, the switching loss under EDPWM is lower than that under other pulsewidth modulation (PWM) strategies. The performance of EDPWM is analyzed and compared with traditional DPWM, space vector PWM (SVPWM) and virtual SVPWM (VSVPWM) in terms of switching loss, waveform quality, and the ability of NP voltage control. Finally, the feasibility and superiority of the proposed method are verified by experiments.

Natural nanominerals (NNMs) are progressively deposited during earth’s formation. They have shown a broad range of applications from industrial catalysis, environmental treatment, and earth science to pharmaceutics due to their unique nanostructures and characteristics. Here, we first report that NNMs have intrinsic enzyme-like properties and show good biocompatibility. First, we characterized the morphology and structure of the six most representative NNMs including sepiolite, attapulgite, halloysite, montmorillonite, kaolinite, and diatomite by SEM, TEM, and XRD. Then, we quantitatively tested their peroxidase- (POD-), catalase- (CAT-), oxidase- (OXD-), and superoxide dismutase- (SOD-) like activities. The results indicate that different kinds of NNMs show varying degrees of POD-like, CAT-like, and SOD-like activities and minor OXD-like activity. Finally, we tested their cytotoxicity and found that the selected representative NNMs have no or less influence on cell viability, showing high biosafety. At present, NNMs have been widely used, mostly focusing on the physical and chemical properties, such as luminescence and conductivity. Our work promotes the understanding of NNMs, providing a new direction for the better application of NNMs.

Virtual space vector pulsewidth modulation (VSVPWM) for the neutral-point (NP)-clamped three-level inverter is briefly reviewed in this paper, as well as its carrier-based realization. The carrier-based VSVPWM (CB_VSVPWM) is featured with dual modulation waves and a single carrier. Although CB_VSVPWM can make NP voltage unfluctuating in theory, it does not have the NP voltage recovery ability. In practice, due to the effect of nonidea factor effects, NP voltage may shift. Thus, active NP voltage control (ANPVC) is necessary. To achieve that, three ANPVC approaches are proposed based on CB_VSVPWM in this paper. The NP voltage control ability of CB_VSVPWM with ANPVC is analyzed. Finally, comprehensive experiments are carried out to verify the feasibility of the proposed method.

The three phases of brushless dc motor (BLDCM) are involved in energy conversion during the commutation interval. A novel commutation analysis method of the BLDCM based on coordinate transformation theory is proposed in this paper, though this coordinate transformation theory is popular in the control of three-phase sinusoidal motors, such as induction motors and permanent magnet synchronous motors. The method is intuitive and easy to understand compared with the method based on circuit solving. Combined with the voltage vector diagram of the inverter, commutation control to reduce commutation torque ripple under low speed (LS_RCTR) and high speed (HS_RCTR) is deduced. However, under a heavy load and high-speed condition, long commutation time may result in commutation failure if these commutation controls to RCTR is adopted. To avoid that, commutation time must be controlled. Then, commutation control to reduce commutation time under low-speed (LS_RCT) and high-speed (two cases, named HS_RCT1 and HS_RCT2) are proposed. The improved control of BLDCM presented in this paper can coordinate commutation torque ripple and commutation time in full speed range. Finally, the feasibility and effectiveness of these methods are verified by experiment.

Nowadays, studies of the control of brushless dc motor (BLDCM) are mainly focused on motor state. However, it may also work in generator state. Current hysteresis control (CHC) is very suitable for the motor control, because it can directly control current. In this paper, a multimode CHC for BLDCM in motor and generator state is presented. It can not only complete commutation successfully but also reduce commutation torque ripple. Moreover, a novel transition control method based on the background of CHC with fast response is proposed to carry out commutation and the transition processes simultaneously. Finally, the effectiveness and insensitivity to the parameters of the proposed control algorithm are verified by experiments.

Nanomaterials with intrinsic enzyme-like activities (nanozymes), have been widely used as artificial enzymes in biomedicine. However, how to control their in vivo performance in a target cell is still challenging. Here we report a strategy to coordinate nanozymes to target tumor cells and selectively perform their activity to destruct tumors. We develop a nanozyme using nitrogen-doped porous carbon nanospheres which possess four enzyme-like activities (oxidase, peroxidase, catalase and superoxide dismutase) responsible for reactive oxygen species regulation. We then introduce ferritin to guide nitrogen-doped porous carbon nanospheres into lysosomes and boost reactive oxygen species generation in a tumor-specific manner, resulting in significant tumor regression in human tumor xenograft mice models. Together, our study provides evidence that nitrogen-doped porous carbon nanospheres are powerful nanozymes capable of regulating intracellular reactive oxygen species, and ferritinylation is a promising strategy to render nanozymes to target tumor cells for in vivo tumor catalytic therapy., If decorated with the right surface modifications, nanoparticles can function as Trojan horses, transporting cell death-facilitating compounds to tumor cells. Here, the authors prepare a particle with four enzyme-like activities and show that ferritin can direct nanoparticles to tumor cells.

A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of five new spiro diterpenoids (1 −5) from the aerial parts of Scutellaria formosana. The structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established via comparison of experimental and calculated electronic circular dichroism (ECD) spectra. The nitric oxide (NO) inhibitory effects were evaluated and all of the compounds showed inhibitory effects on lipopolysaccharide-induced NO production in murine microglial BV-2 cells. The possible mechanism of NO inhibition of bioactive compounds was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the iNOS protein.

Two parallel grid-connected inverters can increase system capacitance effectively. In order to exert maximum efficiency of parallel grid-connected inverters, an optimal power allocation (OPA) method is proposed. Firstly, the power model of every inverter is established. Compared with the equal power allocation (EPA) method, theoretically, higher overall system efficiency can be achieved with the OPA method. Secondly, the overall system efficiency can be calculated with easily measurable electric parameters, and the online optimization realized by adopting an existing method, such as the hill-climbing method. Lastly, the feasibility of the OPA method is verified by simulation and experimentation.

A phytochemical investigation to obtain new NO inhibitors led to the isolation of nine compounds including one new guaiane-type sesquiterpenoid (1) and two new cleistanthane diterpenoids (2 and 3) from the stems of Trigonostemon howii. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of new compounds 1–3 were established via comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 2 and 3 possess a rare 3,4-seco-cleistanthane diterpenoid skeleton. All of the compounds showed inhibitory effects on lipopolysaccharide-induced NO production in murine microglial BV-2 cells. The further molecular docking studies indicated the strong interactions between some bioactive compounds with the iNOS protein, which revealed the possible and potential mechanism of NO inhibition of bioactive compounds.

Tussilago farfara L. is a well-known herb plant and used widely in China, North Africa, and Europe. A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of three new sesquiterpenes, one new phenolic derivative, and ten known compounds from the flower buds of T. farfara . Their structures were established on the basis of extensive analyses of nuclear magnetic resonance (NMR) spectroscopic data. All of the isolates exhibited inhibitory effects on LPS-induced NO production in BV-2 cells. The possible mechanism of NO inhibition was also investigated using molecular docking, which revealed the interactions of bioactive compounds with iNOS protein. The present study disclosed that flower buds of T. farfara have the potential to be developed into a functional food.

A few rice (Oryza sativa L.) varieties or rice straw produce and release allelochemicals into soil in which interfere with the growth of neighboring or successive plants. Allelopathic rice PI312777 and Huagan-1 at their early growth stages released momilactone B, 3-isopropyl-5-acetoxycyclohexene-2-one-1, and 5,7,4′-trihydroxy-3′,5′-dimethoxyflavone into soil at phytotoxic levels, but non-allelopathic rice Huajingxian did not. Both allelopathic and non-allelopathic rice residues released momilactone B and lignin-related phenolic acids (p-hydroxybenzoic, p-coumaric, ferulic, syringic and vanillic acids) into the soil during residue decomposition to inhibit successive plants. The results indicated that allelochemicals involved in rice allelopathy from living and dead plants are substantially different. Interestingly, the concentrations of the allelochemicals released from the allelopathic rice seedlings in soil increased dramatically when they were surrounded with Echinochloa crus-galli. The concentrations of the allelochemicals were over 3-fold higher in the presence of E. crus-galli than in the absence of E. crus-galli. However, the same case did not occur in non-allelopathic Huajingxian seedlings surrounded with E. crus-galli. In addition to allelochemical exudation being promoted by the presence of E. crus-galli, allelopathic rice seedlings also increased allelochemical exudation in response to exudates of germinated E. crus-galli seeds or lepidimoide, an uronic acid derivative exuded from E. crus-galli seeds. These results imply that allelopathic rice seedlings can sense certain allelochemicals released by E. crus-galli into the soil, and respond by increased production of allelochemicals inhibitory to E. crus-galli. This study suggests that rice residues of both allelopathic and non-allelopathic varieties release similar concentrations and types of allelochemicals to inhibit successive plants. In contrast, living rice plants of certain allelopathic varieties appear to be able to detect the presence of interspecific neighbors and respond by increased allelochemicals.