Tannic-Acid-Enriched Poly(vinyl alcohol) Nanofibrous Membrane as a UV-Shie lding and Antibacterial Face Mask Filter Material.

Face masks are increasingly important in the battle against infectious diseases and air pollution. Nanofibrous membranes (NFMs) are promising filter layers for removing particulate matter (PM) without restricting air permeability. In this study, tannic-acid-enriched poly(vinyl alcohol) (PVA-TA) NFMs were fabricated by electrospinning PVA solutions containing large amounts of tannic acid (TA), a multifunctional polyphenol compound. We were able to prepare uniform electrospinning solution without coacervate formation by inhibiting the robust hydrogen bonding between PVA and TA. Notably, the NFM maintained its fibrous structure even under moist conditions after heat treatment without the use of a cross-linking agent. Further, the mechanical strength and thermal stability of the PVA NFM were improved by the introduction of TA. The functional PVA NFM with a high TA content showed excellent UV-shielding (UV-A: 95.7%, UV-B: 100%) and antibacterial activity against Escherichia coli (inhibition zone: 8.7 ± 1.2 mm) and Staphylococcus aureus (inhibition zone: 13.7 ± 0.6 mm). Moreover, the particle filtration efficiency of the PVA-TA NFM for PM0.6 particles was 97.7% at 32 L min-1 and 99.5% at 85 L min-1, indicating excellent filtration performance and a low pressure drop. Therefore, the TA-enriched PVA NFM is a promising mask filter layer material with excellent UV-blocking and antibacterial properties and has the potential for various practical applications.

Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan.

In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (-500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal-Wallis test and a post hoc Mann-Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then -500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of -500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.

Treatment of ingrown nail with a special device composed of shape-memory alloy.

Ingrown nail is a common nail problem resulting in pain and disability in daily life. Recently, a new treatment modality for an ingrown nail was reported that used a device composed of shape-memory alloy, K-D. The aim of the present study was to determine the efficacy, recurrence rate and complications of K-D. Between June 2010 and September 2012, 24 patients (31 nails) underwent treatment of symptomatic incurved nails with a K-D. Patients were evaluated at pretreatment and during every visit. The mean age of the patients involved was 43.4 years. The mean period of follow up was 161 days. The mean maintenance period was 41 days. The right first toenail was the most common site. Almost ingrown nails healed and the nail deformity was corrected after the procedure. Among the 31 nails, seven of the ingrown nails recurred during follow up (22.6% recurrence rate). The recurrence rate of the patients with stage 1, 2 and 3 ingrown nails was 22.2%, 33.3% and 14.2%, respectively. The majority of patients were very satisfied. There were no side-effects in most patients except loss of nail in one patient. K-D has some advantages such as simple application steps, no deformity after the procedure, high patient satisfaction and obvious effect compared to other non-invasive and invasive methods.