A practical graphitic carbon nitride (g-C₃N₄)based fluorescence sensor for the competitive detection of trithiocyanuric acid and mercury ions

[EN] A fluorescent sensor for the detection of trithiocyanuric acid (TCA) and Hg was developed based on competitive interactions: non-covalent stacking between g-CN and TCA vs coordinative interaction between TCA and Hg. Electrostatic simulations were used to evaluate the interactions and help describe the detection mechanism. Moreover, normalized 2D fluorescence contour plots have been used to understand the fluorescence phenomenon. When TCA was added into a g-CN nanosheet solution free of Hg, TCA interacted with g-CN nanosheets via hydrogen bonding and π-π interactions, resulting in fluorescence quenching of the g-CN nanosheets. However, upon the addition of Hg, the fluorescence of the TCA-g-CN nanosheet hybrid system was restored, due to coordination of Hg with TCA through the S atoms, breaking the TCA-g-CN stacking interaction. Our results provide a new approach for the design of multifunctional nanosensors suitable for the detection of environmental pollutants.The present work is supported by the National Natural Science Foundation of China (No. 21607044), the Natural Science Foundation of Hebei Province (No. B2017502069) and the Fundamental Research Funds for the Central Universities (No. 2018MS113). All data sup-porting this study are provided as supplementary information accom-panying this paper. T.D.J. wishes to thank the Royal Society for a Wolfson Research Merit Award

Poor nutritional status is associated with incomplete functional recovery in elderly patients with mild traumatic brain injury

BackgroundThe geriatric nutritional risk index (GNRI) is a simple index for evaluating the nutrition status of elderly patients. Many investigations have demonstrated that this index is associated with the prognosis of several diseases. This study aims to identify the relationship between the GNRI and recovery in elderly mild traumatic brain injury (mTBI) patients.MethodsA total of 228 mTBI patients older than 65 years were included in this study. mTBI was defined as an injury to the brain with a loss of consciousness of 30 min or less, a duration of posttraumatic amnesia of <24 h, and an admission Glasgow Coma Scale (GCS) score of 13–15. The Glasgow Outcome Scale Extended (GOSE), an outcome scale assessing functional independence, work, social activities, and personal relationships, was applied to assess the recovery of the patients. The clinical outcome was divided into complete recovery (GOSE = 8) and incomplete recovery (GOSE ≤ 7) at 6 months after the injury. Multivariate logistic regression was applied to evaluate the association between the GNRI and recovery of elderly mTBI patients, with adjustment for age, sex, hypertension, diabetes, and other important factors.ResultsThe receiver operating curve (ROC) analysis demonstrated that the cutoff value of GNRI was 97.85, and the area under the curve (AUC) was 0.860. Compared to the patients with a high GNRI, the patients with a low GNRI were older, had a higher prevalence of anemia, acute subdural hematoma, and subarachnoid hemorrhage, had a higher age-adjusted Charlson Comorbidity Index value, and had lower levels of albumin, lymphocytes, and hemoglobin. Multivariable analysis showed that high GNRI was associated with a lower risk of 6-month incomplete recovery (OR, 0.770, 95% CI: 0.709–0.837, p < 0.001).ConclusionThe GNRI has utility as part of the objective risk assessment of incomplete 6-month functional recovery in elderly patients with mTBI

The gut microbiome dysbiosis and regulation by fecal microbiota transplantation: umbrella review

BackgroundGut microbiome dysbiosis has been implicated in various gastrointestinal and extra-gastrointestinal diseases, but evidence on the efficacy and safety of fecal microbiota transplantation (FMT) for therapeutic indications remains unclear.MethodsThe gutMDisorder database was used to summarize the associations between gut microbiome dysbiosis and diseases. We performed an umbrella review of published meta-analyses to determine the evidence synthesis on the efficacy and safety of FMT in treating various diseases. Our study was registered in PROSPERO (CRD42022301226).ResultsGut microbiome dysbiosis was associated with 117 gastrointestinal and extra-gastrointestinal. Colorectal cancer was associated with 92 dysbiosis. Dysbiosis involving Firmicutes (phylum) was associated with 34 diseases. We identified 62 published meta-analyses of FMT. FMT was found to be effective for 13 diseases, with a 95.56% cure rate (95% CI: 93.88–97.05%) for recurrent Chloridoids difficile infection (rCDI). Evidence was high quality for rCDI and moderate to high quality for ulcerative colitis and Crohn’s disease but low to very low quality for other diseases.ConclusionGut microbiome dysbiosis may be implicated in numerous diseases. Substantial evidence suggests FMT improves clinical outcomes for certain indications, but evidence quality varies greatly depending on the specific indication, route of administration, frequency of instillation, fecal preparation, and donor type. This variability should inform clinical, policy, and implementation decisions regarding FMT

Study on potential gradient in Ti anodization

Porous oxides or nanotubes are obtained through the anodization of valve metal. However, the mechanism of nanotube growth remains unclear. Traditional field-assisted dissolution (FAD) theory has many limitations, such as its inability to explain the connotation of the three stages in the current–time curve. By placing a container between two electrodes, the ions move around the container in a ring in the present study. The potential gradient during anodization was innovatively changed. Finally, the current–time curve obtained during anodization using the new device is quite different from that obtained using conventional anodizing device. This phenomenon is explained by the electronic current and ionic current theory in this paper

A practical graphitic carbon nitride (g-C₃N₄)based fluorescence sensor for the competitive detection of trithiocyanuric acid and mercury ions

A fluorescent sensor for the detection of trithiocyanuric acid (TCA)and Hg2+ was developed based on competitive interactions: non-covalent stacking between g-C3N4 and TCA vs coordinative interaction between TCA and Hg2+. Electrostatic simulations were used to evaluate the interactions and help describe the detection mechanism. Moreover, normalized 2D fluorescence contour plots have been used to understand the fluorescence phenomenon. When TCA was added into a g-C3N4 nanosheet solution free of Hg2+, TCA interacted with g-C3N4 nanosheets via hydrogen bonding and π-π interactions, resulting in fluorescence quenching of the g-C3N4 nanosheets. However, upon the addition of Hg2+, the fluorescence of the TCA-g-C3N4 nanosheet hybrid system was restored, due to coordination of Hg2+ with TCA through the S atoms, breaking the TCA-g-C3N4 stacking interaction. Our results provide a new approach for the design of multifunctional nanosensors suitable for the detection of environmental pollutants.</p

Experimental analysis on friction-induced vibration of water-lubricated bearings in a submarine propulsion system

© 2020 Elsevier Ltd Abnormal vibration and noise, originated from friction and wear, are often found in water-lubricated stern-tube bearings, which seriously threatens the safety and concealment of underwater vehicles. In order to better understand the friction-induced vibration in water-lubricated stern-tube bearings, friction pairs of rubber specimens matched with ZQSn10-2 brass were tested on the water-lubricated bearing test rig SBB-100. A high-speed camera was used to track the micro images that focused on of the rubber layer vibration motion, while a machine vision technique also was employed to extract the friction-induced vibration of the test bearings. The experimental analysis results demonstrate that the bearing vibration was mainly induced by stick-slip. Furthermore, the orthogonal experiment method was used to distinguish the key factors that induce the bearing vibration among rotating speed, contact pressure, rubber layer hardness and thickness, and lubrication condition. The analysis results indicate that the importance of factors is sorted in the order of lubrication condition, contact pressure, hardness and thickness of rubber layers. In normal lubrication condition, the intensity of friction-induced vibration of the rubber bearings can be reduced by increasing the hardness of the rubber layer, decreasing the contact pressure, and the thickness of the rubber layer

Bamboo shoot nanotubes with diameters increasing from top to bottom: Evidence against the field-assisted dissolution equilibrium theory

The formation mechanism of anodic TiO2 nanotubes remains controversial. To further explore the growth of nanotubes, we compared the difference between galvanostatic and potentiostatic anodizing processes, and discovered that the electric current kept dropping in the final phase of the potentiostatic process, whereas the voltage kept rising in the final phase of the galvanostatic process. Therefore, the so-called steady growth state of the field-assisted dissolution equilibrium model was not observed in either anodizing process. Furthermore, during galvanostatic anodization, we discovered for the first time that the diameters of the nanotubes gradually increased from top to bottom (from 134.9 nm to 202.0 nm). Bamboo shoot nanotubes with increasing diameters were fabricated through one-step and multi-step galvanostatic anodizations. These experimental observations cannot be explained by the field-assisted dissolution equilibrium theory. However, the electronic current model provides a reasonable explanation for the results obtained in this paper. Keywords: Anodization, TiO2 nanotubes, Dissolution equilibrium, Formation mechanis