[Impacts of COVID-19 Lockdown on Air Quality in Shenzhen in Spring 2022]

The short-term reduction of air pollutant emissions is an important emergency control measure for avoiding air pollution exceedances in Chinese cities. However, the impacts of short-term emission reductions on the air qualities in southern Chinese cities in spring has not been fully explored. We analyzed the changes in air quality in Shenzhen, Guangdong before, during, and after a city-wide lockdown associated with COVID-19 control during March 14 to 20, 2022. Stable weather conditions prevailed before and during the lockdown, such that local air pollution was strongly affected by local emissions. In-situ measurements and WRF-GC simulations over the Pearl River Delta (PRD) both showed that, due to reductions in traffic emissions during the lockdown, the concentrations of nitrogen dioxide (NO₂), respirable particulate matter (PM₁₀), and fine particulate matters (PM_2.5) in Shenzhen decreased by (-26±9.5)%, (-28±6.4)%, and (-20±8.2)%, respectively. However, surface ozone (O₃) concentration did not change significantly[(-1.0±6.5)%]. TROPOMI satellite observations of formaldehyde and nitrogen dioxide column concentrations indicated that the ozone photochemistry in the PRD in spring 2022 was mainly controlled by the volatile organic compound (VOCs) concentrations and was not sensitive to the reduction in nitrogen oxide (NO_x) concentrations. Reduction in NO_x may even have increased O_3, because the titration of O₃ by NO_x was weakened. Due to the small spatial-temporal extent of emission reductions, the air quality effects caused by this short-term urban-scale lockdown were weaker than the air quality effects across China during the widespread COVID-19 lockdown in 2020. Future air quality management in South China cities should consider the impacts of NO_x emission reduction on ozone and focus on the co-reduction scenarios of NO_x and VOCs.

Diversity of cultivable endophytic fungi in two Rubia plants and their potential for production of anti-tumour Rubiaceae-type cyclopeptides

Rubia plants are one of the most important plant resources possessing significant commercial and medicinal values. Plant endophytes could benefit their host plants in different ways. Rubiaceae-type cyclopeptides (RAs), mainly isolated from Rubia plants, have attracted considerable attentions for their distinctive bicyclic structures and significant antitumor activities, but their contents in plants are low. The aim of this study is to investigate the diversity of endophytic fungi in Rubia plants and their potential for production of RAs. In this work, 143 endophytic fungi isolates were obtained from two Rubia plants. Phylogenetic analysis was performed based on the ITS rDNA sequences, and the isolates were classified into 29 genera. Among them, four endophytic fungal strains were found to produce anti-tumour RAs by LC-MS/MS analysis. This work successfully provides valuable knowledges of endophytic fungi microbiome in Rubia plants for agricultural and industrial applications, and exploits a new environmental-friendly resource of RAs.

[Efficacy of lobaplatin plus S-1 and the predictive value of circulating tumor cell in patients with advanced gastric cancer]

Objective: To investigate the efficacy and safety of lobaplatin (LBP) plus S-1 for advanced gastric cancer (AGC) and determine the potential role of circulating tumor cells (CTC) for predicting the therapeutic response and prognosis. Methods: From January 2014 to February 2015, 64 consecutive patients with AGC received lobaplatin plus S-1 chemotherapy in Liaocheng People's Hospital. The clinical features, clinical response, adverse effects, prognosis and CTC pre- and post-treatment were retrospectively analyzed. The correlation between CTC and patients' disease control rate (DCR), objective response rate (ORR), progression free survival (PFS) as well as overall survival (OS) were investigated. Results: All 64 patients completed 2 cycles of chemotherapy.The number of patients who achieved complete regression, partial regression, stable and progression were 0, 24 (37.5%), 18 (28.1%) and 22 (34.4%), respectively. ORR was 37.5% and DCR was 65.6%. The median PFS was 10.8 months(95%CI 7.1-12.0) and the median OS was 16.1 months(95%CI 12.4-18.8). The ORR and PFS were not significantly different between patients with baseline CTC≥2 and CTC<2 (25.0% vs 53.6%, P=0.150; 6.2 months vs 7.5 months, P=0.780), while the DCR and OS were significantly different (45.9% vs 90.0%, P=0.008; 10.5 months vs 17.2 months, P<0.001). After 2 cycles of chemotherapy, the ORR and DCR in patients with CTC≥2 were 16.7% and 45.9%, respectively, which were significantly lower than those observed in patients with CTC<2 (50.0% and 90.0%, respectively). The former also had shorter median PFS and OS (6.6 months vs 8.9 months, 8.4 months vs 15.0 months, respectively). Patients with persistently CTC<2 or those exhibiting an conversion to CTC<2 following chemotherapy had an improved PFS and OS, while patients with persistently CTC≥2 or those exhibiting an conversion to CTC≥2 following therapy had shorter PFS and OS.The most frequent adverse effects were grade 1 or 2 gastrointestinal discomfort and myelosuppression. No patients discontinued chemotherapy because of adverse events. Conclusions: Lobaplatin plus S-1 had manageable safety profile and promising antitumor activity in patients with AGC. CTC could be used as a biomarker in evaluating therapeutic response and predicting their prognosis.

[Effect of radiation dose and dose rate on pulmonary fibrosis in mice]

OBJECTIVE

To study the effect of radiation dose and dose rate on radiation-induced pulmonary fibrosis in mice.

METHODS

Twenty-four C57BL/6 mice were randomly divided into a control group (n=6) and an irradiation group(n=18). The irradiation group was further assigned to 3 subgroups according to the whole lung radiation with 15 Gy at 400 cGy/min, 20 Gy at 400 cGy/min and 20 Gy at 100 cGy/min, while the control group received sham-irradiation. All mice were scanned with computed tomograph (CT) 20 weeks post-irradiation, and then they were sacrificed and lung tissues were collected. H&E staining, sirius red staining, lung fibrosis scored and hydroxyproline content analysis were used to assess lung fibrosis and collagen deposition. Real time PCR was used to measure the mRNA expression of type Ⅰ collagen. Immunohistochemical staining was used to detect the activatin and distribution of a-SMA(+) -myofibroblasts.

RESULTS

Compared to the control group, mice from irradiation groups exhibited significant pulmonary consolidation and collagen deposition.At the same dose rate, the higher irradiated dose used, the more severe pulmonary fibrosis was.On the other hand, with the same dose, the dose rate had less effect on pulmonary fibrosis.

CONCLUSION

The effect of radiation dose on the degree of pulmonary fibrosis in mice is more than effect of the dose rate.

Ultra long SiCN nanowires and SiCN/SiO2 nanocables: synthesis, characterization, and electrical property

SiCN nanowires are synthesized by pyrolysis of hexamethyldisilazane (HMDSN) using ferrocene as a catalyst precursor at 1200 degrees C in a flowing argon atmosphere on the surface of mullite substrate, polycrystalline alumina wafer and quartz tube. In oxygen-contained argon atmosphere, SiCN/SiO2 nanocables are synthesized. The as-synthesized products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution electron microscopy equipped with energy dispersive X-ray spectroscopy. The lengths of the nanowires and nanocables are in the millimeter range. The diameter of the SiCN nanowires grown on mullite substrate and alumina wafer ranges from about 10-70 nm, while that of the nanowires grown on quartz tube surface is in the range of around 7-10 nm. The diameters of the SiCN/SiO2 nanocables are relatively large. A vapor-liquid-solid growth mechanism of the nanostructures is proposed. The electrical resistivity of a single SiCN/SiO2 nanocable is reported for the first time.

A simple route to ultra long SiC nanowires

SiC nanowires are prepared by pyrolysis of hexamethyldisilane (HMDS), at 1200 degrees C in a flowing Ar atmosphere. The length of the nanowires is in millimeter scale. Transmission electron microscopy observations indicate that the diameters of the SiC nanowires are in the range of about 8 to 120 nm, and that most of the nanowires have numerous stacking faults. The formation mechanism of the nanowires is proposed.

The effect of component placement on knee kinetics after arthroplasty with an unconstrained prosthesis

The mechanical success of a total knee replacement demands stable patellar tracking without subluxation and, stable tracking, in turn, can depend largely on the medial-lateral forces restraining the patella. Patellar button medialization has been advocated as a means of reducing subluxation, and experimental evidence has shown femoral component rotation also affects medial-lateral forces. Surgeons have choices in femoral component rotation and patellar button medialization and must frequently make intra-operative decisions concerning component placement because of anatomical variations among patients. Thus, in seeking to minimize medial-lateral patellar force, we examined the effects of patellar button medialization and external femoral component rotation. The study used an unconstrained total knee system implanted in nine cadaveric specimens tested on a knee simulator operating through flexion angles up to 100 degrees. Tests included all combinations of external femoral component rotation of 0 degree, 2.5 degrees, and 5 degrees and patellar placement at the geometric center and at 3.75 mm medial to the geometric center. A video-based motion analysis system tracked patellar and tibial kinematics while a six-component load cell measured patellofemoral loads. Repeated measures analysis of variance revealed a statistically significant decrease in the average medial-lateral force with button medialization but no significant change with femoral component rotation. Neither femoral component rotation nor patellar button medialization had an effect on the normal component of the patellar reaction force. External femoral component rotation did cause significant increases in lateral patellar tilt, in tibial varus angle, and in external tibial rotation. Button medialization caused significant increases in lateral patellar tracking, lateral patellar tilt and external tibial rotation. The results in medial-lateral patellar forces quantify the benefit of patellar button medialization and discount any benefit of femoral rotation. The change in tibial kinematics with patellar button medialization and femoral component rotation cannot be measured in vivo with current technology, and the precise clinical implications are unknown.