Brain Activation Evoked by Motor Imagery in Pediatric Patients with Complete Spinal Cord Injury

BACKGROUND AND PURPOSE

Currently, there is no effective treatment for pediatric patients with complete spinal cord injury. Motor imagery has been proposed as an alternative to physical training for patients who are unable to move voluntarily. Our aim was to reveal the potential mechanism of motor imagery in the rehabilitation of pediatric complete spinal cord injury.

MATERIALS AND METHODS

Twenty-six pediatric patients with complete spinal cord injury and 26 age- and sex-matched healthy children as healthy controls were recruited. All participants underwent the motor imagery task-related fMRI scans, and additional motor execution scans were performed only on healthy controls. First, we compared the brain-activation patterns between motor imagery and motor execution in healthy controls. Then, we compared the brain activation of motor imagery between the 2 groups and compared the brain activation of motor imagery in pediatric patients with complete spinal cord injury and that of motor execution in healthy controls.

RESULTS

In healthy controls, compared with motor execution, motor imagery showed increased activation in the left inferior parietal lobule and decreased activation in the left supplementary motor area, paracentral lobule, middle cingulate cortex, and right insula. In addition, our results revealed that the 2 groups both activated the bilateral supplementary motor area, middle cingulate cortex and left inferior parietal lobule, and supramarginal gyrus during motor imagery. Compared with healthy controls, higher activation in the bilateral paracentral lobule, supplementary motor area, putamen, and cerebellar lobules III-V was detected in pediatric complete spinal cord injury during motor imagery, and the activation of these regions was even higher than that of healthy controls during motor execution.

CONCLUSIONS

Our study demonstrated that part of the motor imagery network was functionally preserved in pediatric complete spinal cord injury and could be activated through motor imagery. In addition, higher-level activation in sensorimotor-related regions was also found in pediatric complete spinal cord injury during motor imagery. Our findings may provide a theoretic basis for the application of motor imagery training in pediatric complete spinal cord injury.

[Analysis of the risk factors of persistent inflammation-immunosuppression-catabolism syndrome in patients with extensive burns]

Objective: To investigate the risk factors and treatment outcome of persistent inflammation-immunosuppression-catabolism syndrome (PICS) in patients with extensive burns. Methods: A retrospective case series study was conducted. From January 2017 to December 2021, 220 patients with extensive burns who were admitted to Guangzhou Red Cross Hospital of Jinan University met the inclusion criteria, including 168 males and 52 females, aged 18-84 (43±14) years. According to the occurrence of PICS, the patients were divided into PICS group (84 patients) and non-PICS group (136 patients). The general data such as sex, age, complication of underlying diseases and acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score on admission, sepsis-related organ failure evaluation (SOFA) scores on admission and 14 days post admission, and proportion of patients with mechanical ventilation over 48 h during treatment, special conditions such as total burn area, full-thickness burn area, proportion of patients admitted within 48 h post injury, and exposed deep wound area at the 30th day post injury, outcome indicators such as hospitalization day, total cost of hospital stay, number of surgeries, and death of patients in the 2 groups were collected and analyzed. Data were statistically analyzed with independent sample t test, Mann-Whitney U test, and chi-square test. The multivariate logistic regression analysis was performed on the indicators with statistically significant differences between the two groups except for outcome indicators, and the independent risk factors influencing secondary PICS in patients with extensive burns were screened. Results: The APACHE Ⅱ and SOFA scores on admission, and proportion of patients with mechanical ventilation over 48 h during treatment of patients in PICS group were significantly higher than those in non-PICS group (t=6.78, Z=-4.75, χ2=4.74, respectively, P<0.05). There were no statistically significant differences in the rest of general data of patients between the two groups (P>0.05). The total burn area, full-thickness burn area, and exposed deep wound area at the 30th day post injury in PICS group were significantly greater than those in non-PICS group (t=6.29, Z=-7.25, Z=-8.73, P<0.05), the exposed deep wound areas at the 30th day post injury in PICS group and non-PICS group were respectively 25% (15%, 35%) total body surface area (TBSA) and 8% (0, 13%) TBSA, while the proportion of patients admitted within 48 h post injury was significantly lower than that in non-PICS group (χ2=6.13, P<0.05). The hospitalization day, total cost of hospital stay, and number of surgeries of patients in PICS group were significantly higher than those in non-PICS group (with Z values of -7.12, -8.48, and -6.87, respectively, P<0.05), while the deaths of patients in the 2 groups were similar (P>0.05). The APACHE Ⅱ score on admission and exposed deep wound area at the 30th day post injury both were the independent risk factors for PICS in patients with extensive burns (with odds ratios of 1.15 and 1.07, 95% confidence intervals of 1.06-1.25 and 1.05-1.10, respectively, P<0.05). Conclusions: The APACHE Ⅱ score on admission and exposed deep wound area at the 30th day post injury are the independent risk factors for PICS in patients with extensive burns. The patients with secondary PICS had good prognosis with more surgical intervention and hospitalization day, and higher total cost of hospital stay.

[Clinical evaluation of antral septal maxillary sinus floor elevation by the disk-up sinus reamer]

Objective: To investigate the clinical effect of disk-up sinus reamer (DSR) in maxillary sinus floor elevation with maxillary sinus septum. Methods: Twenty-four patients were included between January 2019 to January 2020 in Department of Oral Implantology, The Affiliated Hospital of Qingdao University. There were 10 males and 14 females with the age of (39.3±11.7) years old (range 22-56 years). Pre-operative(T0) cone-beam CT (CBCT) was taken for measurement and analysis. All patients were divided into group E (easy situations, septum located anterior to the zygo-matic process), group M (moderate situations, septum located pos-terior to the zygo-matic process) and group D (difficult situations, sagittally oriented septum). The maxillary sinus floor was grafted through the crestal approach by DSR and implants were placed simultaneously. Permanent repair was performed 6-8 months after operation. All patients underwent CBCT before surgery, after surgery immediately (T1), 6 months after surgery(T2), 1 year after surgery(T3), 2 year after surgery(T4). The residual bone height (RBH) and the vertical bone height (VBH) were analyzed. The mucosal perforation rate, implant survival rate were counted. Results: All the 24 patients completed the Maxillary sinus lift surgery successfully and 24 implants were placed simultaneously. All patients had no headache, dizziness. The mucosal perforation rate was 0. The survival rate of implants during the healing period was 100%(24/24). The RBH was (5.81±2.56) mm pre-operation, the VBHT1, VBHT2, VBHT3 and VBHT4 were (11.82±1.09), (10.98±0.52), (10.66±0.44) and (10.40±0.33) mm, respectively. The differences between the groups by pairing test were statistically significant (F=187.70, P0.001), expect VBHT3 and VBHT4 (P=0.071). Bone resorption and remodeling mainly occurred 1 year after surgery. One patient developed peri-implantitis 18 months after surgery. Conclusions: With the RBH of implant site>2 mm and existence of maxillary sinus septum, using DSR for sinus floor elevation has a high success rate. It can obtain enough bone height and complete the simultaneous implantation to form a good osseointegration. The DSR is simple, safe and controllable, and can shorten the operation time.

Achieving High Responsivity and Detectivity in a Quantum-Dot-in-Perovskite Photodetector

This work reports on quantum dots (QDs) in perovskite photodetectors showing high optoelectronic performance via quantum-dot-assisted charge transmission. The self-powered broad-band photodetector constructed with SnS QDs in FAPb_0.5Sn_0.5I₃ perovskite can capture incoming optical signals directly at zero bias. The QDs-in-perovskite photodetector exhibits a high sensitivity in the wavelength range from 300 to 1000 nm. Its responsivity at 850 nm reaches 521.7 mA W^-1, and a high specific detectivity of 2.57 × 10¹² jones can be achieved, which is well beyond the level of previous self-powered broad-band photodetectors. The capability of quantum-dot-in-perovskite photodetectors as data receivers has been further demonstrated in a visible-light communication application.

Isolation, identification, and evaluation of the biocontrol potential of a Bacillus velezensis strain against tobacco root rot caused by Fusarium oxysporum

AIMS

Tobacco (Nicotiana tabacum) is an economically important crop. Root rot caused by Fusarium oxysporum has become a damaging disease in N. tabacum crops grown in Henan province of China. Therefore, the objectives of this study were to screen bacterial isolates against F. oxysporum from rhizosphere soils of tobacco growing areas and to evaluate their antifungal activities, biocontrol effects, and effects on plant growth.

METHODS AND RESULTS

Nineteen strains with antifungal inhibition effects of >60% against F. oxysporum were obtained using the method of flat confrontation; the strain Ba-0321 was the strongest, with an antifungal effect of 75%. Moreover, this strain had broad spectrum antimicrobial activity to eight additional tobacco pathogens. The strain was identified as Bacillus velezensis by morphology and the 16S rDNA sequence. The B. velezensis strain Ba-0321 had strong UV resistance as well as tolerance to high temperatures and low nutrition. The bacteria inhibited spore germination and mycelial growth of F. oxysporum under in vitro co-culture conditions. In vivo assays demonstrated that the Ba-0321 strain significantly reduced the pathogenicity of F. oxysporum, resulting in a control effect on tobacco root rot of 81.00%. Simultaneously, the bacteria significantly promoted root development and the growth of tobacco plants.

CONCLUSION

Our results confirmed that the B. velezensis strain Ba-0321 has a strong antifungal effect and stress resistance that enable it to be used as a biological control agent for tobacco root rot caused by F. oxysporum.

SIGNIFICANCE AND IMPACT OF THE STUDY

Tobacco root rot caused by F. oxysporum has become a damaging disease in China. The B. velezensis strain Ba-0321 has promising application value for controlling tobacco root rot diseases, and it could provide a new biocontrol agent against root rot caused by F. oxysporum in other plant species.

Surgical sequence in anterior column realignment with posterior osteotomy is important for degree of adult spinal deformity correction: advantages and indications for posterior to anterior sequence

BACKGROUND

We hypothesized that posterior osteotomy prior to ACR (Anterior column realignment) through P-A-P surgical sequence would permit a greater correction for deformity corrective surgery than the traditional A-P sequence without posterior osteotomy. This study aimed to determine the impact of the P-A-P sequence on the restoration of lumbar lordosis (LL) compared to the A-P sequence in deformity corrective surgery for adult spinal deformity (ASD) patients and to identify the characteristics of patients who require this sequence.  METHODS: Between 2017 and 2019, 260 ASD patients who had undergone combined corrective surgery were reviewed retrospectively. This study included 178 patients who underwent posterior osteotomy before the ACR (P-A group) and 82 patients who underwent the A-P sequence (A-P group). Sagittal spinopelvic parameters were determined from pre- and postoperative whole-spine radiographs and compared between the groups. To find better indications for the P-A-P sequence, we conducted additional analysis on postoperative outcomes of patients in the A-P group.  RESULTS: The P-A group showed a significantly higher change in LL (53.7° vs. 44.3°, p < 0.001), C7 sagittal vertical axis (C7 SVA: 197.4 mm vs. 146.1 mm, p = 0.021), segmental lordosis (SL) L2/3 (16.2° vs. 14.4°, p = 0.043), SL L3/4 (16.2° vs. 13.8°, p = 0.004), and SL L4/5 (15.1° vs. 11.3°, p = 0.001) compared to the A-P group. At the final follow-up, pelvic incidence (PI) minus LL mismatch (PI - LL mismatch) was significantly higher in the A-P group (13.4° vs. 2.9°, p < 0.001). Stepwise logistic regression analysis showed that age ≥ 75 years (odds ratio [OR] = 2.151; 95% confidence interval [CI], 1.414-3.272; p < 0.001), severe osteoporosis (OR = 2.824; 95% CI, 1.481-5.381; p = 0.002), rigid lumbar curve with dynamic changes in LL < 10° (OR = 5.150; 95% CI, 2.296-11.548; p < 0.001), and severe facet joint osteoarthritis (OR = 4.513; 95% CI, 1.958-10.402; p < 0.001) were independent risk factors for PI - LL mismatch ≥ 10° after A-P surgery.

CONCLUSION

P-A-P sequence for deformity corrective surgery in ASD offers greater LL correction than the A-P sequence. Indications for the procedure include patients aged ≥ 75 years, severe osteoporosis, rigid lumbar curve with dynamic change in LL < 10°, or more than four facet joints of Pathria grade 3 in the lumbar region.

Significantly Enhanced Energy Storage Performance of Lead-Free BiFeO3-Based Ceramics via Synergic Optimization Strategy

Owing to the merits of giant power density and ultrafast charge-discharge time, dielectric capacitors including ceramics and films have inspired increasing interest lately. Nevertheless, the energy storage density of dielectric ceramics should be further optimized to cater to the boosting demand for the compact and portable electronic devices. Herein, an ultrahigh recoverable energy storage density W_rec of 13.44 J/cm³ and a high efficiency η of 90.14% are simultaneously realized in BiFeO₃-BaTiO₃-NaTaO₃ relaxor ferroelectric ceramics with high polarization P_max, reduced remanent polarization P_r, and optimized electric breakdown strength E_b. High P_max originates from the genes of BiFeO₃-based ceramics, and reduced P_r is induced by enhanced relaxor behavior. Particularly, a large E_b is achieved by the synergic contributions from complicated internal and external factors, such as decreased grain size and improved resistivity and electrical homogeneity. Furthermore, the ceramics also exhibit satisfactory frequency, cycling and thermal reliability, and decent charge-discharge property. This work not only indicates that the BiFeO₃-based relaxor ferroelectric materials are promising choices for the next-generation electrostatic capacitors but also paves a potential approach to exploit novel high-performance dielectric ceramics.

[Analysis of the clinical characteristics and risk factors of postoperative atrial fibrillation in patients with critical burns]

Objective: To investigate the clinical characteristics and risk factors of postoperative atrial fibrillation (POAF) in patients with critical burns. Methods: A retrospective case series study was conducted. From January 2017 to December 2021, two hundred and twenty-seven critically burned aldult patients who met the inclusion criteria were admitted to Guangzhou Red Cross Hospital of Jinan University, including 173 males and 54 females, aged 19-83 (43±14) years. The admission years of patients were collected, and the percentage of patients complicated with POAF in each year was calculated. According to whether the patients were complicated with POAF or not, they were divided into POAF group (n=17) and non-POAF group (n=210). Following data were collected in patients in POAF group, including operation methods, duration of operation, intraoperative blood loss before occurrence of POAF each time, occurrence time and times of POAF, postoperative body temperature, blood pressure, hemoglobin, blood glucose, blood lactate, sepsis, and electrolyte, and type, duration, and treatment of POAF. General data of patients in the two groups including age, gender, burn reason, total burn area, full-thickness burn area, acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) and sepsis-related organ failure evaluation (SOFA) scores on admission, combined with underlying diseases (hypertension, diabetes, and other types of arrhythmias), and sepsis were collected and analyzed. The mortality and factors influencing the prognosis of patients in the two groups such as mechanical ventilation time, operations times, and burn intensive care unit (BICU) length of stay were also collected and analyzed. Data were statistically analyzed with independent sample t test, Mann-Whitney U test, chi-square test or Kruskal-Wallis H test. The multivariate logistic regression analysis was performed on the general data with statistically significant differences between the two groups, and the independent risk factors influencing the onset of POAF in 227 patients with critical burns were screened. Results: From 2017 to 2021, the percentage of critically burned patients complicated with POAF increased year by year. In POAF group, eschar debridement in limbs was the main surgical procedure prior to POAF complication, with the operation time of (3.5±1.2) h and the intraoperative blood loss volume of (365±148) mL.The POAF occurred 25 times in total in patients of POAF group, mostly within one week after the injury and within 6 hours after the operation with most of these patients having POAF only once. When POAF happened, the patients were often complicated with hypothermia, anemia, hyperglycemia, high blood lactate, sepsis, and electrolyte disturbance, and few patients had complications of hypotension. The POAF lasted (5±3) h, with all being paroxysmal atrial fibrillation, and most of POAF patients were reverted to sinus rhythm after amiodarone intervention. Most patients in the two groups suffered from flame burn, and the gender, age, and SOFA score on admission of patients in the two groups were similar (P>0.05); the APACHEⅡ score on admission, total burn area, full-thickness burn area, incidence proportion of sepsis, combined with diabetes and hypertension and other types of arrhythmias of patients in POAF group were significantly higher or larger than those in non-POAF group (t=3.47, with χ2 values of 7.44, 10.86, 12.63, 14.65, 6.49, and 7.52, respectively, P<0.05 or P<0.01). The full-thickness burn area, combined with other types of arrhythmias, and sepsis were the independent risk factors for POAF in 227 critically burned patients (with odds ratios of 4.45, 0.04, and 3.06, respectively, with 95% confidence intervals of 2.23-8.87, 0.01-0.22, and 1.77-5.30, respectively, P<0.01). Compared with those in non-POAF group, the mechanical ventilation time, BICU length of stay, number of operations, and mortality rate of patients in POAF group were significantly increased (Z=3.89, Z=2.57, t=3.41, χ2=3.72, P<0.05 or P<0.01). Conclusions: POAF is a common postoperative complication in critically burned patients, and the incidence is increasing year by year, which seriously affects the prognosis of patients. The full-thickness burn area together with other types of arrhythmias and sepsis are the high-risk factors for POAF complication in patients with critical burns.

Ultrahigh Energy Storage Density and High Efficiency in Lead-Free (Bi0.9Na0.1)(Fe0.8Ti0.2)O3-Modified NaNbO3 Ceramics via Stabilizing the Antiferroelectric Phase and Enhancing Relaxor Behavior

Dielectric capacitors have attracted growing attention because of their important applications in advanced high power and/or pulsed power electronic devices. Nevertheless, the synergistic enhancement of recoverable energy storage density (W_rec > 10 J/cm³) and efficiency (η > 80%) is still a great challenge for lead-free dielectric bulk ceramics. Herein, by introducing complex perovskite compound (Bi_0.9Na_0.1)(Fe_0.8Ti_0.2)O₃ with a smaller tolerance factor into an NaNbO₃ matrix (NN-BNFT), we have achieved and explored stable relaxor antiferroelectric ceramics with enhanced relaxor behavior. Of particular importance is the composition of 0.88NN-0.12BNFT, which exhibits a large electric breakdown strength E_b of 87.3 kV/mm, an ultrahigh W_rec of 12.7 J/cm³, and a high efficiency η of 82.5%, as well as excellent thermal reliability and an ultrafast discharge speed, resulting from the dense microstructure, the moderate dielectric constant, the reduced grain size, the dielectric loss, and the sample thickness. The outstanding energy storage properties of NN-BNFT display great promise in advanced dielectric capacitors for energy storage applications.

[Myocardial biopsy of Liwen procedure: representability and etiological diagnostic value of cardiac samples obtained by a novel technique in patients with hypertrophic cardiomyopathy]

Objective: To investigate the representability and etiological diagnostic value of myocardium samples obtained from patients with hypertrophic cardiomyopathy (HCM) by transthoracic echocardiography-guided percutaneous intramyocardial septal biopsy (myocardial biopsy of Liwen procedure). Methods: This study was a retrospective case-series analysis. Patients with HCM, who underwent myocardial biopsy of Liwen procedure and radiofrequency ablation in Xijing Hospital, Air Force Military Medical University from July to December 2019, were included. Demographic data (age, sex), echocardiographic data and complications were collected through electronic medical record system. The histological and echocardiographic features, pathological characteristics of the biopsied myocardium of the patients were analyzed. Results: A total of 21 patients (aged (51.2±14.5) years and 13 males (61.9%)) were enrolled. The thickness of ventricular septum was (23.3±4.5)mm and the left ventricular outflow tract gradient was (78.8±42.6)mmHg (1 mmHg=0.133 kPa). Eight patients (38.1%) were complicated with hypertension, 1 patient (4.8%) had diabetes, and 2 patients (9.5%) had atrial fibrillation. Hematoxylin-eosin staining of myocardial samples of HCM patients before radiofrequency ablation evidenced myocytes hypertrophy, myocytes disarray, nuclear hyperchromatism, hypertrophy, atypia, coronary microvessel abnormalities, adipocyte infiltration, inflammatory cell infiltration, cytoplasmic vacuoles, lipofuscin deposition. Interstitial fibrosis and replacement fibrosis were detected in Masson stained biopsy samples. Hematoxylin-eosin staining of myocardial samples of HCM patients after radiofrequency ablation showed significantly reduced myocytes, cracked nuclear in myocytes, coagulative necrosis, border disappearance and nuclear fragmentation. Quantitative analysis of myocardial specimens of HCM patients before radiofrequency ablation showed that there were 9 cases (42.9%) with mild myocardial hypertrophy and 12 cases (57.1%) with severe myocardial hypertrophy. Mild, moderate and severe fibrosis were 5 (23.8%), 9 (42.9%) and 7 (33.3%), respectively. Six cases (28.6%) had myocytes disarray. There were 11 cases (52.4%) of coronary microvessel abnormalities, 4 cases (19.0%) of adipocyte infiltration, 2 cases (9.5%) of inflammatory cell infiltration,6 cases (28.5%) of cytoplasmic vacuole, 16 cases (76.2%) of lipofuscin deposition. The diameter of cardiac myocytes was (25.2±2.8)μm, and the percentage of collagen fiber area was 5.2%(3.0%, 14.6%). One patient had severe replacement fibrosis in the myocardium, with a fibrotic area of 67.0%. The rest of the patients had interstitial fibrosis. The myocardial specimens of 13 patients were examined by transmission electron microscopy. All showed increased myofibrils, and 9 cases had disorder of myofibrils. All patients had irregular shape of myocardial nucleus, partial depression, mild mitochondrial swelling, fracture and reduction of mitochondrial crest, and local aggregation of myofibrillary interfascicles. One patient had hypertrophy of cardiomyocytes, but the arrangement of muscle fibers was roughly normal. There were vacuoles in the cytoplasm, and Periodic acid-Schiff staining was positive. Transmission electron microscopy showed large range of glycogen deposition in the cytoplasm, with occasional double membrane surround, which was highly indicative of glycogen storage disease. No deposition of glycolipid substance in lysozyme was observed under transmission electron microscope in all myocardial specimens, which could basically eliminate Fabry disease. No apple green substance was found under polarized light after Congo red staining, which could basically exclude cardiac amyloidosis. Conclusion: Myocardium biopsied samples obtained by Liwen procedure of HCM patients are representative and helpful for the etiological diagnosis of HCM.

[Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in 13 children]

Objective: To analyze the clinical characteristics, treatment and prognosis of Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in children. Methods: A retrospective analysis was performed on the clinical features, laboratory tests, neuroelectrophysiological examination, imaging, treatment and outcomes of 13 patients with Hashimoto's encephalopathy presenting with isolated cerebellar ataxia, who were admitted to the Department of Pediatric Neurology of Guangzhou Women and Children's Medical Center from January 2016 to May 2021. Results: Among the 13 cases, 6 were males and 7 were females. The onset age was 2.6 (2.0,3.3) years, 9 children had precursor infection or vaccination before the first course of disease. All the 13 children had gait abnormalities or unsteady sitting, 10 had intentional tremor, 6 had dysarthria, 3 had body tremor, 2 had nystagmus, 3 had fatigue, 3 had hypotonia, 2 had vomiting and 1 had irritability. Thyroglobulin antibody (TgAb) was 500.0 (298.9,587.2) kU/L and thyroid peroxidase antibody (TPOAb) was 621.9 (449.6,869.4) kU/L in 13 cases. Autoantibodies were positive in 9 cases, and cerebrospinal fluid leukocytosis was seen in 4 cases. Regarding electroencephalography result, 4 cases had background slowing and 1 case had occasional sharp waves. Among the 3 patients who had relapses, 1 had cerebellar atrophy shown on cranial magnetic resonance imaging (MRI) during the recurrence. All the patients received intravenous immunoglobulin (IVIG) and intensive methylprednisolone therapy during the first onset, followed by the disappearance of the symptoms, 1 patient had repeated episodes which was decreased after immunosuppressive treatment with Rituximab.Followed up for 25.0 (22.5,33.3) months after the last episode, 12 achieved complete remission and 1 had a wide base gait. Conclusions: Trunk ataxia is the common symptom of Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in children.Children with cerebellar ataxia should be tested for TgAb and TPOAb to detect Hashimoto's encephalopathy, avoiding missed diagnosis and treatment delays; IVIG and intensive steroid therapy is effective, and immunosuppressive therapy for patients with multiple relapses could reduce the recurrence.

Detection of blaKPC and blaNDM genes by duplex PCR with lateral flow dipsticks from sterile body fluid samples

Duplex polymerase chain reaction with lateral flow dipsticks (duplex PCR-LFD) was developed for the simultaneous detection of beta-lactamase Klebsiella pneumoniae carbapenemase (bla_KPC ) and beta-lactamase New Dehli metallo-beta-lactamase (bla_NDM ) genes in body fluid samples. This method was validated using well-characterized isolates. The assessment of the specificity of duplex PCR-LFD showed that there was no cross-reactivity with other targets. The detection limit of the duplex PCR-LFD assay was 20 CFU per ml for bla_KPC and bla_NDM . Among 177 sterile body fluid samples tested by the duplex PCR-LFD assay, 40 were bla_KPC -positive and five were bla_NDM -positive. The results obtained from 122 corresponding Gram-negative bacteria which were isolated from these clinical samples and tested by duplex PCR-LFD assay showed that there were 37 strains carrying bla_KPC genes in 40 bla_KPC -positive samples and three strains carrying bla_NDM genes in five bla_NDM -positive samples. Statistical analysis indicated that there was no significant difference between the direct detection of bla_KPC and bla_NDM genes in clinical sterile body fluid samples and their corresponding clinical isolates. Therefore, duplex PCR-LFD can be effective for the simultaneous detection of bla_KPC and bla_NDM in clinical isolates and directly from clinical samples, which may be helpful for the administration of appropriate antimicrobial treatment.

[Investigation of occupational hazard of 750 kV extra high voltage substations]

Objective: To understand the current status of major occupational hazards in 750 kV extra high voltage (EHV) substations. Methods: In July 2019, through investigating and detecting the sulfur hexafluoride, power frequency electric field and noise occupational hazards of 750 kV EHV substations in substation 1, substation 2, substation 3, substation 4, substation 5, substation 6 and substation 7, the exposure intensity of the sulfur hexafluoride, power frequency electric field and noise intensity that the operators are exposed to during the inspection process were analyzed. Results: The qualified rate of 358 sulfur hexafluoride test results was 100.0% of the seven 750 kV EHV substations. The qualified rate of 8 h time-weighted average of the power frequency electric field of those 750 kV EHV substations contacted by operators was 100.0%. Among the 847 power frequency electric field detection points, the exceeding standard rate of power frequency electric field was 64.3%, and the differences in the power frequency electric field detection exceeding standard rates of different substations and inspection areas were statistically significant (χ²=87.52, 50.86, P<0.01) . The highest exceeding standard rate of power frequency electric field was the circuit breaker inspection area (94.4%, 34/36) . The noise intensity test results of the seven EHV substations were 41.1-79.7 dB (A) , and the qualified rate was 100.0%. Conclusion: The sulfur hexafluoride, power frequency electric field and noise that the operators contacted in 750 kV EHV substations meet the requirements of occupational exposure limits. The inspection areas of main transformers, capacitors, reactors, bus bars and switches have high power frequency electric field radiation, should be select equipment iand give priority to robot inspection, and reasonably adjust the inspection time to reduce the intensity level of substation operators' exposure to power frequency electric field.

[Hesitancy of parents towards vaccines in national immunization program in three regions in China: a cross-sectional study]

Objective: To investigate the incidence and determinants of vaccine hesitancy towards national immunization program in China and understand the current status of parents' hesitancy to different vaccines used in national immunization program. Methods: A cross-sectional survey was conducted in Beijing, Sichuan and Gansu. The methods of proportional probability sampling and convenience sampling were used to select the eligible study subjects for questionnaire surveys. Results: A total of 3 592 parents were enrolled in the study, in whom 38.22% fully accepted all the vaccines, 59.35% agreed to let their children to receive all the vaccines but showed slight concern, and 2.42% had hesitancy to the vaccines. The vaccine with the most hesitancy was polio vaccine (0.89%), followed by diphtheria pertussis tetanus vaccine (0.70%) and hepatitis A vaccine (0.64%). The dominant reason for vaccine hesitancy was the risk-benefit perception of vaccination (31.03%), followed by the low awareness of the parents (21.84%) and the inconvenience caused by distance and time (21.84%). Conclusions: The incidence of vaccine hesitancy towards national immunization program was low in parents in China, but over 50% of the parents showed concern to the vaccines. It is essential to improve the service quality of national immunization program and strengthen the health education about the vaccination to reduce the incidence of vaccine hesitancy in parents.

[Determination of hydrazine in workplace air by gas chromatography with large bore capillary column]

Objective: To determine hydrazine quantitatively in workplace air by gas chromatography with large bore capillary column. Methods: In October 2019, hydrazine in the air was adsorbed by acid silica gel tube sampling and desorped using sulfuric acid solution. After derivatization with furfural and extraction, the content of hydrazine was determined by DM-FFAP capillary column gas chromatography with flame ionization detector. Results: The linear regression equation was y=353.8x+21.2 (r=0.9998) between 0.1-2.0 μg/ml of target concentration. The detection limit was 0.030 μg/ml. The lower limit of quantification was 0.100 μg/ml. If 15 L air sample was collected, the minimum detection concentration was 0.004 mg/m(3) and the minimum quantitative concentration was 0.013 mg/m(3) respectively. The average desorption efficiency was 86.5%-89.4%. The recovery was 94.4%-97.1%. The relative standard deviation was 1.6%-4.9%. Hydrazine and furfural derivative was 2-furaldehyde hydrazine. Conclusion: The method has symmetrical peak shape of hydrazine derivatives chromatographic peaks, short analysis time, easy operation, and is suitable for the determination of the concentration of hydrazine in the air in the workplace.

Enhanced energy storage density of all-organic fluoropolymer composite dielectric via introducing crosslinked structure

Polymer-based dielectrics have been attracted much attention to flexible energy storage devices due to their rapid charge–discharge rate, flexibility, lightness and compactness. Nevertheless, the energy storage performance of these dielectric polymers was limited by the weak dielectric breakdown properties. Crosslinked structure has been proven efficient to enhance breakdown strength (E_b) and charge–discharge efficiency (η) of polymer film capacitors. However, crosslinked networks usually lead to low electric displacement of dielectric capacitors, which greatly restrict their energy storage density (U_d). In this work, we present a tri-layered composite via layer-by-layer casting technology, where crosslinked polyvinylidene fluoride (c-PVDF) was used as the inter-layer to offer high breakdown strength, and the outer ternary fluoropolymer layers with high dielectric constant could provide high electric displacement. The optimal tri-layered composites exhibit an ultrahigh discharge energy density of 18.3 J cm⁻³ and a discharge efficiency of 60.6% at 550 kV mm⁻¹. This energy density is much higher than that of the PVDF terpolymer and commercially biaxially oriented polypropylene (BOPP, 1–2 J cm⁻³). The simulation results prove that the enhanced energy density originates from the effectively depressed charge transport in crosslinked structure at high applied electric field. Moreover, this work provides a feasible method for developing flexible all-organic high-energy-density composites for polymer capacitors.

High energy density is achieved for all-organic composites by introducing crosslinked structure.

[Application of pulse contour cardiac output monitoring technology in fluid resuscitation of severe burn patients in shock period]

Objective: To investigate the application of pulse contour cardiac output (PiCCO) monitoring technology in fluid resuscitation of severe burn patients in shock period. Methods: From January 2015 to December 2019, 33 patients with severe burns who were hospitalized in Guangzhou Red Cross Hospital, meeting the inclusion criteria, were recruited into a retrospective cohort study with their clinical information collected. The patients were divided into PiCCO monitoring group with 15 cases (13 males and 2 females, aged (43±13) years) and routine monitoring group with 18 cases (14 males and 4 females, aged (39±9) years) according to the monitoring method used. After admission, all the patients were rehydrated following the rehydration formula of the Third Military Medical University for shock period. In routine monitoring group, the fluid resuscitation of patients was performed by monitoring indicators such as urine volume and blood pressure, while PiCCO monitoring was performed among patients in PiCCO monitoring group, and their fluid resuscitation was guided by the patient's condition and the hemodynamic parameters (without pursuing normal levels of the parameters) of PiCCO monitoring on the basis of normal monitoring indicators in routine monitoring group. The colloids coefficients, the electrolyte coefficients (compared with the corresponding rehydration formula value of 0.75 mL·kg(-1)·% total body surface area (TBSA)(-1) of the Third Military Medical University for shock period during the first 24 h post injury), the total rehydration coefficients, and the urine volumes during the first and second 24 h post injury, the lactic acid level, the base excess level, and the oxygenation index at admission and 24, 48 h after admission, and the mechanical ventilation time, the wound healing time, and the death ratio of patients in the two groups were recorded. The cardiac index, the global end-diastolic volume index (GEDVI), the intrathoracic blood volume index (ITBVI), the extravascular lung water index (EVLWI), and the systemic vascular resistance index (SVRI) of patients in PiCCO monitoring group at post injury hour 24, 48, and 72 and the abnormal cases were recorded. Data were statistically analyzed with Fisher's exact probability test, independent-sample or one-sample t test, analysis of variance for repeated measurement, and Bonferroni correction. Results: During the first 24 h post injury, the colloids coefficients of patients in PiCCO monitoring group was (0.69±0.15) mL·kg(-1)·%TBSA(-1), which was significantly less than (0.85±0.16) mL·kg(-1)·%TBSA(-1) in routine monitoring group (t=-2.612, P<0.05). Compared with the rehydration formula value of the Third Military Medical University for shock period, only the colloids coefficient of patients in routine monitoring group during the first 24 h post injury was significantly increased (t=2.847, P<0.05). There were no statistically significant differences between the two groups in the colloids coefficients of patients during the second 24 h post injury, or the electrolyte coefficients, the total rehydration coefficients, the urine volumes of patients during the first and the second 24 h post injury (t=0.579, -0.011, 0.417, -1.321, -0.137, 0.031, 1.348, P>0.05). The lactic acid level, the base excess level, the oxygenation index of patients at admission and 48 h after admission, and the oxygenation index of patients at 24 h after admission between the two groups were similar (t=-1.837, 0.620, 0.292, -1.792, 1.912, -0.167, 1.695, P>0.05). The levels of lactic acid and base excess of patients in PiCCO monitoring group were (4.8±1.4) and (1.2±5.5)mmol/L, respectively, which were significantly better than (7.0±1.5) and (-2.8±3.0) mmol/L in routine monitoring group at 24 h after admission (t=-3.904, 2.562, P<0.05 or P<0.01). There were no statistically significant differences between the two groups in the mechanical ventilation time or the wound healing time of patients (t=-0.699, -0.697, P>0.05), or the death ratio of patients (P>0.05). In PiCCO monitoring group, the GEDVI, and the ITBVI of patients were lower than the normal low values at post injury hour 24 and 48, which were in the normal range at post injury hour 72; the cardiac index of patients increased gradually and recovered to normal at post injury hour 48; the SVRI of patients increased significantly at post injury hour 24 and then gradually decreased to normal; the EVLWI average of patients at all time points post injury were less than 10 mL/kg. At post injury hour 24, most of the hemodynamic parameters of more than or equal to 8/15 patients in PiCCO monitoring group were abnormal, and the abnormal proportion decreased later. Conclusions: On the basis of traditional monitoring indicators, the use of PiCCO monitoring technology combined with the patient's condition (without pursuing normal levels of the parameters) in guiding the fluid resuscitation in severe burn patients can reduce the usage of colloid and better improve tissue perfusion, with the resuscitation effect being better than conventional monitoring.

Synthesis and characterization of an anti-caries and remineralizing fluorine-containing cationic polymer PHMB-F

Dental caries have become a major global public health problem. Plaque control and remineralization of initial enamel lesions are paramount for the prevention and control of caries. Polyhexamethylene biguanide (PHMB) is a type of cationic amphipathic antibacterial agent with broad-spectrum antibacterial properties and good biological safety. Fluoride delays demineralization and promotes the remineralization of hard dental tissues. However, a high concentration is needed for it to function as an antibacterial agent. In order to create a PHMB with the benefits associated with fluoride, we synthesized a fluorine-containing cationic polymer, PHMB-F. Fourier transform-infrared spectroscopy and solid state nuclear magnetic resonance characterization confirmed the successful synthesis of PHMB-F. Antibacterial tests showed that PHMB-F had better antiseptic efficacy for Streptococcus mutans compared with just PHMB. Moreover, positively-charged PHMB-F allows fluoride ions to exist closer to the enamel surface with negative potential, which markedly lowers the ion concentrations in the microenvironment adjacent to hard dental tissues needed to maintain equilibrium. Thus, only low concentrations of PHMB-F are required for enamel remineralization.