Ultrathin Bismuth Nanosheets as a Highly Efficient CO2 Reduction Electrocatalyst

Electrochemical reduction of CO₂ to value-added products is an important and challenging reaction for sustainable energy study. Herein, bismuth nanosheets with thickness of around 10 nm were prepared through the electrochemical reduction of Bi³⁺ . Ultrathin Bi nanosheets with numerous low-coordination sites can efficiently reduce CO₂ to formate in aqueous solution. Within the potential range of -0.9 to -1.2 V vs. reversible hydrogen electrode (RHE), the faradaic efficiency of formate is over 90 %, outperforming many Bi catalysts. At -0.7 V, the Bi nanosheets exhibit much higher current for formate generation than that of bulk Bi, attributed to a high surface area and also modified intrinsic electronic properties brought about by the ultrathin structure. DFT calculations demonstrate that Bi nanosheets have much higher density of states at the Fermi level compared to bulk Bi, favoring improved CO₂ reduction on Bi nanosheets. At -1.0 V, Bi nanosheets exhibit high selectivity for formate and excellent stability during 5 h of electrolysis.

An evaluation of the quality of root fillings in mandibular incisors and maxillary and mandibular canines using different methodologies

OBJECTIVES

To evaluate the quality of root fillings in mandibular incisors and maxillary and mandibular canines using different methodologies of evaluation, namely radiographs, the fluid transport test and the percentage of gutta-percha (PGP), and to determine if a correlation occurs between the results of the different methodologies used.

METHODS

One group of mandibular incisors with oval canals (n=20) and one group of maxillary and mandibular canines (n=20) were instrumented and obturated by cold lateral compaction using AH 26 as the sealer. The filled roots were bucco-lingually and mesio-distally radiographed. Using a scoring system, the quality of each root filling was radiographically evaluated, the higher the score the poorer the quality. Fluid transport along the root filling was then measured using a fluid transportation device. Each root was horizontally sectioned 4 and 6mm from the apex. Images of the cross-sections were taken, using a microscope and a digital camera. Images were scanned into a PC as TIFF images. Using a KS 100 Imaging system the canal area and the gutta-percha filled areas were measured. The percentage of gutta-percha filled areas was calculated.

RESULTS

Considering the radiographic scores of the two different projections together the score was significantly higher for the mandibular incisors than for the canines (P=0.039). The radiographic score was significantly higher for the mesio-distal radiograph in comparison with the bucco-lingual radiograph (P=0.0001), for the canines as well as the incisors. Using only the bucco-lingual radiograph there was no significant difference between the mandibular incisors and the canines (P=0.992). The mandibular incisors displayed significantly more fluid transport than the canines (P=0.049). A significantly greater percentage of gutta-percha filled areas was found in the cross-sections of canines as compared to the cross-sections of mandibular incisors (P=0.000001). The correlation between the radiographic score of the mesio-distal radiograph and the PGP 4 and 6mm was significant (P=0.013). There was no significant correlation between the FT and the radiograph or the FT and the PGP.

CONCLUSIONS

The quality of the root fillings in oval canal-mandibular incisors may be compromised.

Heavy metal poisoning in glass worker characterised by severe

The paper presents the clinical description of the masticatory organ and biochemical assessment of dental tissue in a patient employed in a glassworks for 20 years. During 12 years the patient has suffered baldness ("Alopecia areata") and atypical extensive and non-healing cutaneous lesions. Dental examination revealed changes typical of chronic poisoning by cadmium and bismuth compounds.

Comparison of sensitivities of cells to X-ray therapy, chemotherapy, and isotope therapy using a tumor spheroid model

Numerous treatment modalities have been used in treating microscopic carcinoma confined to the peritoneal cavity. However, there is little information at the cellular level regarding which modality is most effective in eradicating small nests of tumor cells. In order to determine whether chemotherapy, X rays, or isotope therapy is most effective, we have compared in a three-dimensional spheroid model the survival of cells after treatment with cis-platinum, X ray, or the investigational high-energy isotope 212-bismuth (Bi-212). In this study, V-79 cells were grown to 100-microns diameter spheroids. In killing spheroids, high-energy isotopes were at least six times more effective than X rays at fractionated doses of up to 1300 cGy. High-energy isotopes appear also to be as efficient as cis-platinum. Regardless of exposure time to treatment, Bi-212 was more toxic to spheroids than the other treatment modalities. From this study we conclude that high-energy isotope therapy biologically is very effective in eradicating microscopic nests of cells.

A critique of therapeutic trials in Helicobacter pylori-positive functional dyspepsia

BACKGROUND/AIMS

Approximately 50% of patients with functional dyspepsia have Helicobacter pylori infection; it remains controversial whether this infection causes chronic symptoms, but rigorously conducted therapeutic trials should establish whether H. pylori plays a role in functional dyspepsia. The aim here was to determine whether the trials published over the past 10 years were methodologically adequate to establish a role for this infection in functional dyspepsia.

METHODS

A broad-based Medline search to identify all treatment trials published between 1984 and 1993 was performed. All functional dyspepsia trials were systematically analyzed for potential design strengths and weaknesses.

RESULTS

Sixteen trials were included; 8 reported that anti-H. pylori therapy was efficacious and 8 failed to detect a statistically significant benefit. However, in all studies one or more serious methodological weakness was identified, including nonrandomized, non-placebo-controlled designs, lack of maintenance of blindness, application of inadequate outcome measures, failure to eradicate infection and follow up patients after therapy, and inadequate study power.

CONCLUSIONS

There is a pressing need for well-designed trials in H. pylori-positive dyspepsia, and practical suggestions are provided based on a review of the published literature.