Enhancement of Photostabilization of Poly(Vinyl Chloride) in the Presence of Tin–Cephalexin Complexes

Poly(vinyl chloride), PVC, has many attractive properties, including low cost of manufacture, resistance to acid and alkali corrosion, and ease of molding. However, PVC suffers from aging in harsh conditions, leading to the shortening of its useful life. Stability to irradiation, for example, can be improved through the incorporation of additives to PVC. The design, synthesis, and application of new stabilizers continue to attract attention. The current work investigates the effect of three tin–cephalexin complexes on the stability of PVC on irradiation with ultraviolet (UV) light (λ = 313 nm) at 25 °C for a long duration. The PVC was blended with tin–cephalexin complexes at low concentrations (0.5% by weight), and thin films (around 40 µm) were made from the mixed materials. Various methods, including weight loss, infrared spectroscopy, and surface inspection of irradiated films were used to investigate the role played by these additives in the inhibition of PVC photodecomposition. The results confirmed that the additives led to a significant reduction in the rate of photodecomposition of the PVC blends. Tin–cephalexin complexes can absorb harmful radiation, deactivate hydrogen chloride, and scavenge high-energy species such as peroxides, therefore acting as stabilizers for PVC

Enhancement of photostabilization of poly(vinyl chloride) in the presence of tin–cephalexin complexes

Poly(vinyl chloride), PVC, has many attractive properties, including low cost of manufacture, resistance to acid and alkali corrosion, and ease of molding. However, PVC suffers from aging in harsh conditions, leading to the shortening of its useful life. Stability to irradiation, for example, can be improved through the incorporation of additives to PVC. The design, synthesis, and application of new stabilizers continue to attract attention. The current work investigates the effect of three tin–cephalexin complexes on the stability of PVC on irradiation with ultraviolet (UV) light (λ = 313 nm) at 25 °C for a long duration. The PVC was blended with tin–cephalexin complexes at low concentrations (0.5% by weight), and thin films (around 40 µm) were made from the mixed materials. Various methods, including weight loss, infrared spectroscopy, and surface inspection of irradiated films were used to investigate the role played by these additives in the inhibition of PVC photodecomposition. The results confirmed that the additives led to a significant reduction in the rate of photodecomposition of the PVC blends. Tin–cephalexin complexes can absorb harmful radiation, deactivate hydrogen chloride, and scavenge high-energy species such as peroxides, therefore acting as stabilizers for PVC

Appropriateness Criteria for Ureteral Stent Omission following Ureteroscopy for Urinary Stone Disease

Introduction: To bridge the gap between evidence and clinical judgment, we defined scenarios appropriate for ureteral stent omission after uncomplicated ureteroscopy (URS) using the RAND/UCLA Appropriateness Method. We retrospectively assessed rates of appropriate stent omission, with the goal to implement these criteria in clinical practice. Methods: A panel of 15 urologists from the MUSIC (Michigan Urological Surgery Improvement Collaborative) met to define uncomplicated URS and the variables that influence stent omission decision making. Over 2 rounds, they scored clinical scenarios for appropriateness criteria (AC) for stent omission based on a combination of variables. AC were defined by median scores of 1 to 3 (inappropriate), 4 to 6 (uncertain) and 7 to 9 (appropriate). Multivariable analysis determined the association of each variable with AC scores. Uncomplicated URS cases in the MUSIC registry were assigned AC scores and stenting rates assessed. Results: Seven variables affecting stent decision making were identified. Of the 144 scenarios, 26 (18%) were appropriate, 88 (61%) inappropriate and 30 (21%) uncertain for stent omission. Most scenarios appropriate for omission were pre-stented (81%). Scenarios with ureteral access sheath or stones \u3e10 mm were only appropriate if pre-stented. Stenting rates of 5,181 URS cases correlated with AC scores. Stents were placed in 61% of cases appropriate for omission (practice range, 25% to 98%). Conclusions: We defined objective variables and AC for stent omission following uncomplicated URS. AC scores correlated with stenting rates but there was substantial practice variation. Our findings demonstrate that the appropriate use of stent omission is underutilized