Self-powered photoelectrochemical aptasensor based on hollow tubular g-C3N4/Bi/BiVO4 for tobramycin detection.

A highly sensitive photoelectrochemical aptasensor based on phosphorus-doped hollow tubular g-C3N4/Bi/BiVO4 (PT-C3N4/Bi/BiVO4) for tobramycin (TOB) detecting was developed. This aptasensor is a self-powered sensing system which could generate the electrical output under visible light irradiation with no external voltage supply. Based on the surface plasmon resonance (SPR) effect and unique hollow tubular structure of PT-C3N4/Bi/BiVO4, the PEC aptasensor exhibited an enhanced photocurrent and favorably specific response to TOB. Under the optimized conditions, the sensitive aptasensor presented a wider linearity to TOB in the range of 0.01-50 ng mL-1 with a low detection limit of 4.27 pg mL-1. This sensor also displayed a satisfying photoelectrochemical performance with optimistic selectivity and stability. In addition, the proposed aptasensor was successfully applied to the detection of TOB in river water and milk samples.

"Turn-off" photoelectrochemical aptasensor based on g-C3N4/WC/WO3 composites for tobramycin detection.

Tobramycin (TOB), as a widely used antibiotic, poses severe unpredictable risks to ecology and health. Here, a novel photoelectrochemical (PEC) aptasensor based on a "turn-off" PEC mode was constructed for TOB detection. The working electrode could be modified by g-C3N4/WC/WO3 composites and TOB aptamer probes in turn. The TOB aptamer probes could anchor on the g-C3N4/WC/WO3 through π-π stacking interaction to avoid interference from other modifications. When TOB was captured by the aptamer probes anchored on the modified fluorine-doped tin oxide (FTO) electrode, a decreased photocurrent was obtained owing to steric hindrance and hinder electron transfer. Under optimal conditions, 0.005-5 ng mL-1 of TOB could be detected with a detection limit as low as 2 pg mL-1. Meanwhile, actual samples were investigated as well. The proposed sensor shows high specificity, satisfactory detectability, great reproducibility, and may provide a new thought for detecting other pollutants.

Highly efficient photocatalytic degradation of norfloxacin via Bi2Sn2O7/PDIH Z-scheme heterojunction: Influence and mechanism.

The severe pollution caused by antibiotics has prompted considerable concerns in recent decades. In this study, the Bi2Sn2O7/PDIH Z-scheme heterojunction photocatalyst was synthesized and highly photocatalytic activity on norfloxacin was obtained. The degradation of norfloxacin reached 98.71% in 90 min under visible light. The apparent rate constant of norfloxacin (0.4 903 min-1) was 3.65 and 20 times that of PDIH and the Bi2Sn2O7. Meanwhile, XPS, electrochemical, Photoluminescence spectroscopy and electron paramagnetic resonance results showed that Z-scheme charge-transfer process facilitated the spatial carrier separation and preserve redox capability. Furthermore, the degradation intermediates of norfloxacin and their toxicities were evaluated. Finally, in the view of the survey about the impact of different water matrices, it was found that the Bi2Sn2O7/PDIH maintained high efficiency in raw natural water. This work enriched inorganic/organic heterojunction engineering for PDIH, and provided the enormous potential for combining the Bi2Sn2O7 with PDIH to address the antibiotic pollution issues in the actual water treatment.

Satellite-based survey of extreme methane emissions in the Permian basin.

Industrial emissions play a major role in the global methane budget. The Permian basin is thought to be responsible for almost half of the methane emissions from all U.S. oil- and gas-producing regions, but little is known about individual contributors, a prerequisite for mitigation. We use a new class of satellite measurements acquired during several days in 2019 and 2020 to perform the first regional-scale and high-resolution survey of methane sources in the Permian. We find an unexpectedly large number of extreme point sources (37 plumes with emission rates >500 kg hour-1), which account for a range between 31 and 53% of the estimated emissions in the sampled area. Our analysis reveals that new facilities are major emitters in the area, often due to inefficient flaring operations (20% of detections). These results put current practices into question and are relevant to guide emission reduction efforts.

Measurement of internal stray radiation of a thermal infrared spectrometer based on temperature variation.

The level of internal stray radiation is an important criterion to evaluate the performance of a thermal infrared spectrometer. In this study, a novel method is proposed and evaluated to measure the internal stray radiation of a thermal infrared spectrometer based on temperature variation. The proposed method was used to measure the internal stray radiation values of an existing instrument. First, two output gray value curves were constructed for a single spectral channel in a cryogenic detector at two different spectrometer temperatures based on radiometric calibration measurements. Subsequently, the gray value and radiation flux of the internal stray radiation of the spectrometer were calculated. In addition, the internal stray radiation data measured at different spectral channels and different integration times were used to verify and evaluate the proposed method. Results show that the proposed method is valid, and the standard deviations of the various internal radiation values of the tested spectral channels and the various integration times are 3.47% and 1.46%, respectively. The proposed method is adaptable, flexible, and efficient.

Time- & Load-Dependence of Triboelectric Effect.

Time- and load-dependent friction behavior is considered as important for a long time, due to its time-evolution and force-driving characteristics. However, its electronic behavior, mainly considered in triboelectric effect, has almost never been given the full attention and analyses from the above point of view. In this paper, by experimenting with fcc-latticed aluminum and copper friction pairs, the mechanical and electronic behaviors of friction contacts are correlated by time and load analyses, and the behind physical understanding is provided. Most importantly, the difference of "response lag" in force and electricity is discussed, the extreme points of coefficient of friction with the increasing normal loads are observed and explained with the surface properties and dynamical behaviors (i.e. wear), and the micro and macro theories linking tribo-electricity to normal load and wear (i.e. the physical explanation between coupled electrical and mechanical phenomena) are successfully developed and tested.

The cell proliferation, cell cycle and apoptosis effects of cycloartane triterpenoid on HCT116 cells / 中国药理学通报

Aim To investigate the antitumor effects of cimigenol ( KY17 ) , a novel cycloartane triterpenoid from Cimicifuga , in human colon cancer cells (HCT116).Methods MTT assay was used to deter-mine the effect of KY17 on the proliferation of mouse embryonic fibroblasts ( MEF) and human colon cancer HCT116 cell line.Flow cytometry was employed to de-tect the effect of KY17 on HCT116 cell cycle.Fluores-cence microscopy and flow cytometry were used to ana-lyze the apoptosis .Western blot was used to detect the expression of apoptotic protein (PARP).q-PCR ana-lyzed the expression of miRNA-34a.Results The IC50 of KY17 in MEF and HCT116 cells was 27.28 μmol· L-1 and 9.31μmol· L-1 , respectively.KY17 induced HCT116 cell cycle arrest in G2/M phase and the apoptotic protein PARP cleavage . In addition, KY17 up-regulated the expression of p 53 protein and miRNA-34a.Conclusions KY17 inhibits the prolifera-tion and the cell cycle is arrested in G 2/M, inducing the apoptosis of HCT116 cells. The mechanism is probably related to miRNA-34a up-regulation and p53 activation .

Effect of root saponins of Panax notoginseng on different voltage-dependent calcium and potassium ion channels / 中国药理学与毒理学杂志

OBJECTIVE To investigate the effect of root saponins of Panax notoginseng(RPNS) on different voltage-dependent calcium and potassium ion channels. METHODS By using the two-elec?trode voltage clamp (TEVC), the effect of RPNS 0.01, 0.06, 0.1, 0.6, 1 and 4 g · L- 1 was investigated on Cav1.2,and the effect of RPNS 1 g · L-1 was evaluated on Cav2.1,Cav2.2,Cav3.1, KCNH2,KCNQ1,KCNQ1/KCNE1 and BK channel. All the ion channels examined were expressed in Xenopus laevis oocytes. RESULTS TEVC suggested that the effect of RPNS on Cav1.2 exhibited the concentration-response relationship and its EC50 was 0.048 g · L-1. Compared with cell control,TEVC also showed that RPNS 1 g·L-1 had obviously inhibitory effect on Cav1.2,Cav2.2 and Cav3.1,and the inhibitory rate of RPNS 1 g · L-1 on the peak current of Cav1.2,Cav2.2 and Cav3.1 was(57.1 ± 8.6)%, (17.2 ± 0.7)% and(50.2 ± 7.7)%(P<0.01),respectively. RPNS 1 g · L-1 had obviously activated effect on BK channel,and the activated rate of RPNS 1 g·L-1 on the peak current of BK channel was(37.9± 2.7)%(P<0.01). RPNS 1 g·L-1 showed no significant effect on Cav2.1,KCNH2,KCNQ1 and KCNQ1/KCNE1. CONCLUSION RPNS may effectively inhibit Cav1.2 and Cav3.1,activate BK channel,but have little effect on Cav2.1,Cav2.2,KCNH2,KCNQ1 and KCNQ1/KCNE1.

Toward design of magnetic nanoparticle clusters stabilized by biocompatible diblock copolymers for T2-weighted MRI contrast.

We report the fabrication of magnetic particles comprised of clusters of iron oxide nanoparticles, 7.4 nm mean diameter, stabilized by a biocompatible, amphiphilic diblock copolymer, poly(ethylene oxide-b-D,L-lactide). Particles with quantitative incorporation of up to 40 wt % iron oxide and hydrodynamic sizes in the range of 80-170 nm were prepared. The particles consist of hydrophobically modified iron oxide nanoparticles within the core-forming polylactide block with the poly(ethylene oxide) forming a corona to afford aqueous dispersibility. The transverse relaxivities (r2) increased with average particle size and exceeded 200 s(-1) mM Fe(-1) at 1.4 T and 37 °C for iron oxide loadings above 30 wt %. These experimental relaxivities typically agreed to within 15% with the values predicted using analytical models of transverse relaxivity and cluster (particle core) size distributions derived from cryo-TEM measurements. Our results show that the theoretical models can be used for the rational design of biocompatible MRI contrast agents with tailored compositions and size distributions.

New 9, 19-cycloartane triterpenoid from the root of Cimicifuga foetida / 中国天然药物

AIM@#To study the 9, 19-cycloartane triterpenes from the roots of Cimicifuga foetida.@*METHOD@#Chromatographic separations by silica gel, C18 reversed phase silica gel, and high-performance liquid chromatography (HPLC) were used. All of the structures were elucidated on the basis of spectroscopic analysis and chemical methods.@*RESULTS@#Five 9, 19-cycloartane triterpenes, (3β, 12β, 15α, 24R)-12, 2'-diacetoxy-24, 25-epoxy-15-hydroxy-16, 23-dione-3-O-α-L-arabinopyranoside (1), actein (2), 23-epi-26-deoxyactein (3), asiaticoside B (4), and 12β-hydroxycimigenol (5) were isolated from the roots of Cimicifuga foetida.@*CONCLUSION@#Compound 1 is a new triterpene with two acetoxy groups at C-2' and C-12.

A study of the distribution patterns and levels of Salmonella enteritidis in the immune organs of ducklings after oral challenge by serovar-specific real-time PCR.

The objective of this study was to understand the distribution patterns and levels of Salmonella Enteritidis (SE) in the immune organs of ducklings after oral challenge. We conducted serovar-specific real-time polymerase chain reaction (PCR) for SE to detect the genomic DNA of SE in the blood and immune organs, including the bursa of Fabricius, thymus, spleen, and Harderian gland, from ducklings after oral challenge at different time points. The results showed that SE was consistently detected in all the samples. The Harderian gland and spleen tested positive at 8 hr postinoculation (PI). The organism was detected in the blood, bursa of Fabricius, and thymus at 10 hr PI. The copy number of SE DNA in each tissue reached a peak at 24-36 hr PI. The spleen, blood, and Harderian gland contained high concentrations of SE, whereas the thymus and bursa of Fabricius had low concentrations. SE populations began to decrease and were not detectable at 2 days PI, but they were still present up to 9 days PI in the spleen, without producing any apparent symptoms. To validate these results, the indirect immunofluorescent antibody (IFA) technique was used, and the IFA results were similar to those of the fluorescent quantitative-PCR. In conclusion, the results provided insight into the SE life cycle in the immune organs; furthermore, the Harderian gland and spleen were determined to be the primary sites of invasion among the immune organs of normal ducklings after oral SE challenge. This study will help in understanding the pathogenesis of SE infection in vivo and may help in the development of a live Salmonella vaccine in the future.

Comparative analysis of intestinal microbial community diversity between healthy and orally infected ducklings with Salmonella enteritidis by ERIC-PCR.

AIM: To analyze the difference of intestinal microbial community diversity between healthy and (S. enteritidis) orally infected ducklings. METHODS: Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR was applied to analyze the intestinal microbial community diversity and dynamic change including duodenum, jejunum, ileum, cecum and rectum from healthy ducklings and 7-day-old ducklings after oral infection with S. enteritidis at different time points. RESULTS: The intestinal microbial community of the control healthy ducklings was steady and the ERIC-PCR band numbers of the control healthy ducklings were the least with rectum and were the most with caecum. ERIC-PCR bands of orally inoculated ducklings did not obviously change until 24 h after inoculation (p.i.). The numbers of the ERIC-PCR bands gradually decreased from 24 h to 72 h p.i., and then, with the development of disease, the band numbers gradually increased until 6 d p.i. The prominent bacteria changed because of S. enteritidis infection and the DNAstar of staple of ERIC-PCR showed that aerobe and facultative aerobe (Escherichia coli, Shigella, Salmonella) became preponderant bacilli in the intestine of orally infected ducklings with SE. CONCLUSION: This study has provided significant data to clarify the intestinal microbial community diversity and dynamic change of healthy and S. enteritidis orally infected ducklings, and valuable insight into the pathogenesis of S. enteritidis infection in both human and animals.

Application of an indirect immunofluorescent staining method for detection of Salmonella enteritidis in paraffin slices and antigen location in infected duck tissues.

AIM: To detect Salmonella enteritidis (S. enteritidis) in paraffin slices and antigen location in infected duck tissues. METHODS: The rabbits were immunized with purified bacillus to obtain S. enteritidis-specific antibody, which were then extracted by the caprylic-ammonium sulphate method, purified through High-Q columns. An indirect immuno-fluorescent staining method (IFA) was established to detect the S. enteritidis antigen in paraffin slices. Detected S. enteritidis in each organ tissue of ducklings experimentally infected with S. enteritidis. RESULTS: The gland of Garder, heart, kidney, spleen, liver, brain, ileum, jejunum, bursa of Fabricius from S. enteritidis experimentally infected ducklings were positive or strongly positive, and the S. enteritidis antigen mainly distributed in the infected cell cytoplasm. CONCLUSION: IFA is an intuitionist, sensitive and specific method in detecting S. enteritidis antigen in paraffin wax slices, and it is a good method in diagnosis and antigen location of S. enteritidis. We also conclude that the gland of Garder, heart, kidney, spleen, liver, ileum, jejunum are target organs in S. enteritidis infections of duck, and S. enteritidis is an intracellular parasitic bacterium.

Quantitative studies of the regular distribution pattern for Salmonella enteritidis in the internal organs of mice after oral challenge by a specific real-time polymerase chain reaction.

AIM: To identify and understand the regular distribution pattern for Salmonella enteritidis (S. enteritidis) in the internal organs of mice after an oral challenge over a 3 wk period. METHODS: Assays based on the serovar-specific DNA sequence of S. enteritidis from GenBank, and a serovar-specific real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) were developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the blood and the internal organs, including heart, liver, spleen, kidney, pancreas, and gallbladder, from mice after oral challenge at different time points respectively. RESULTS: The results showed that the spleen was positive at 12 h post inoculation (PI), and the blood was at 14 h PI. The organism was detected in the liver and heart at 16 h PI, the pancreas was positive at 20 h PI, and the final organs to show positive results were the kidney and gallbladder at 22 h PI. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h PI, with the liver and spleen containing high concentrations of S. enteritidis, whereas the blood, heart, kidney, pancreas, and gallbladder had low concentrations. S. enteritidis populations began to decrease and were not detectable at 3 d PI, but were still present up to 12 d PI in the gallbladder, 2 wk for the liver, and 3 wk for the spleen without causing apparent symptoms. CONCLUSION: The results provided significant data for understanding the life cycle of S. enteritidis in the internal organs, and showed that the liver and spleen may be the primary sites for setting itself up as a commensa over a long time after oral challenge. Interestingly, it may be the first time reported that the gallbladder is a site of carriage for S. enteritidis over a 12 d period. This study will help to understand the mechanisms of action of S. enteritidis infection in vivo.

Aqueous dispersions of magnetite nanoparticles complexed with copolyether dispersants: experiments and theory.

Magnetite (Fe3O4) nanoparticles have been synthesized and complexed with carboxylate-functional block copolymers, and then aqueous dispersions of the complexes were investigated as functions of their chemical and morphological structures. The block copolymer dispersants had either poly(ethylene oxide), poly(ethylene oxide-co-propylene oxide), or poly(ethylene oxide-b-propylene oxide) outer blocks, and all of them had a polyurethane center block that contained pendent carboxylate groups. The complexes were formed through interactions of the carboxylates with the surfaces of the magnetite nanoparticles. The magnetite cores of the magnetite-copolymer complexes were near 10 nm in diameter, and the particles were superparamagnetic. Complexes with mass ratios of polymer to magnetite varying from 50:50 to 85:15 were studied. One of our objectives is to design complexes that form stable dispersions of discrete particles in water, yet that can be actuated (moved together) upon exposure to a uniform magnetic field. DLVO calculations that accounted for magnetic attractive interparticle forces, as well as van der Waals, steric, and electrostatic forces are presented. Compositions were identified wherein a shallow, attractive interparticle potential minimum appears once the magnetic term is applied. This suggests that it may be possible to tune the structures of superparamagnetic nanoparticle shells to allow discrete dispersions without a field, yet weak flocculation could be induced upon exposure to a field.

[Short and long-term efficacy of focused ultrasound therapy for vulva dystrophy].

OBJECTIVE: To investigate the short and long-term efficacy and complications, as well as the influential factors of focused ultrasound for the treatment of vulva dystrophy. METHODS: Seventy-six eligible patients with vulva dystrophy were randomized and treated with focused ultrasound between 1999 and 2002. Among them, 45 patients were with squamous hyperplasia (SH) and 31 patients were with lichen sclerosus (LS). Colposcopic examination and biopsies were used to monitor and evaluate the changes. Statistical analysis was performed using chi(2) (McNemar chi(2)) test. RESULTS: The median follow-up period was 28.3 month (range 24 months to 60 months). Complete remission (CR) occurred in 39 of 76 patients (27 SH and 12 LS). The cure rate was 51% at four years. The response rate was 95% (72/76). Four of the 76 patients (2 SH and 2 LS) had slight skin burn and a few blisters around the labia 2-4 hours after treatment. Moreover, two patients (1 SH and 1 LS) had superficial ulcers on the treated vulva skin two weeks after ultrasound treatment, which were cured without any complications with local anti-inflammatory drugs for 2-3 weeks. No other long-term side effects were found after a follow up for 24-60 months. The total recurrence rate at four years was 36% (26/72), all of whom were treated again with ultrasound therapy with good results and no complications. There was no obvious difference among the different anaesthesia types and pathological types of the lesions (P > 0.05). However, the shorter the history of the disease, the better the efficacy of the treatment. The younger the patient was, the better the efficacy of the treatment. CONCLUSIONS: Vulva dystrophy can be treated with focused ultrasound effectively and safely. This approach appears to be a new promising treatment method.