Search Results (4)

Background: When scleral buckling is performed using a #240 encircling band anterior to the equator for rhegmatogenous retinal detachment, buckle migration may occur anteriorly, eroding the rectus muscle. There are few cases of buckle migration occurring simultaneously with buckle infection. Notably, most previous reports included inadequate data on the pathophysiology of buckle migration and did not include the Hess test and perioperative images. Case presentation: A 36-year-old man with a history of atopic dermatitis underwent scleral buckling for rhegmatogenous retinal detachment of the left eye with #287 and #240 encircling bands at Kagoshima University Hospital. Four years later, he developed discharge, redness, and diplopia of the left eye. He was then referred to our hospital because buckle infection was suspected. The buckle was partially visible on the lower nasal side. Optical coherence tomography of the anterior chamber revealed the buckle to be on the nasal side and overlying the medial rectus muscle. Buckle migration and infection in the left eye was diagnosed, and early buckle removal was recommended. Two weeks later, on the day before surgery, conjunctival melting progressed in the nasal and inferior areas, and the buckle was exposed to a greater extent. In the surgical video at the initial surgery, the silicone band was confirmed to pass under the four rectus muscles, specifically the inferior and medial rectus muscles. At the beginning of the second surgery, we confirmed that the buckles were over the inferior and medial rectus muscles. As far as could be observed after buckle removal, the inferior and medial rectus muscles were not present at the normal location. Postoperatively, ocular pain and discharge quickly resolved. The subjective symptoms of diplopia also improved, and the postoperative Hess chart showed an improved ocular movement in the upward and lateral directions. Conclusions: Buckle migration is a rare postoperative complication of scleral buckling; however, patients at risk of buckle migration, such as those with encircling scleral buckle anterior to the eyeball, should be monitored with caution. If a buckle infection develops, buckle migration may occur within a short period, and early buckle removal should be considered. Full article

This study develops and characterizes the distinctive mechanical features of a stainless-steel metal stent with a tailored structure. A high-precision femtosecond laser was used to micromachine a stent with re-entrant hexagonal (auxetic) cell geometry. We then characterized its mechanical behavior under various mechanical loadings using in vitro experiments and through finite element analysis. The stent properties, such as the higher capability of the stent to bear upon bending, exceptional advantage at elevated levels of twisting angles, and proper buckling, all ensured a preserved opening to maintain the blood flow. The outcomes of this preliminary study present a potential design for a stent with improved physiologically relevant mechanical conditions such as longitudinal contraction, radial strength, and migration of the stent. Full article

Shape is an essential property of polymeric particles. Herein, we propose a simple method to synthesize polymeric particles with a well-controlled concave shape. Our method takes advantage of the powerful seeded emulsion polymerization strategy with the well-known principle of “like dissolves like” in solvent chemistry. We first prepared polystyrene (PS) particles with a single dimple by seeded emulsion polymerization. Then the dimpled PS particles were dispersed in a dimethylformamide (DMF) and water mixture. Consequently, the non-crosslinked polymer chains inside the particle were dissolved by DMF, a good solvent for PS, and the PS chains migrated out of the particle, causing buckling of the dimple and enlargement of the concave. By systematic change of the fraction of DMF in the solvent mixture, we changed the amount of the dissolved PS chains, and achieved polymeric particles with precisely tuned degree of concaveness. These concave particles were found to readily self-assemble, driven by polymer-induced depletion interaction. The concave PS particles reported here provide potential building blocks for self-assembled polymeric materials, and new model systems for condensed matter research. Full article

Greenstone belts in the West African Craton (WAC) are separated by several generations of granitoids intruded at ca. 2.18–1.98 Ga. Simultaneous folding and exhumation play an important role in the formation of greenstone-granitoid belts. However, the overall tectonic regime and origin of granitoids remain controversial. In this study, we present the estimates of the mantle potential temperature (Tp) for the WAC, which yields values of about 1500–1600 °C, pressure estimates of initial and final melting yield values of about 3.7–5.2 GPa and 1–1.3 GPa, respectively. Subsequently, 2D thermo-mechanical models have been constructed to explore the width of volcano-sedimentary basin on spatial-temporal evolution of diapirs that emplaced in the lower-middle crust during compression. The models show that the width of the volcano-sediment layer plays an important role in the formation mechanisms of greenstone-granitoid belts. The lower crust beneath sedimentary sequences is deformed into a buckle fold during the first compressional stage, through which relief uplifts slowly. Subsequently, the buckle fold is further deformed into several individual folds. Diapirs made of lower crust rocks ascend and emplace in the middle-upper crust resulting from instability. Benefitting from the mantle temperature, the pressure estimates and the numerical modelling results, a new geodynamic model was constructed. This model indicates that a series of sheet-like granitoids possibly derived from either subducted mélanges, lower crust and/or mantle melting that are accumulated at depths of the subcontinental mantle would channel along diapirs before feeding the upper crust. When the granitoids arrive at the solidified lids of the diapirs, they would favour migrating horizontally and intrude into the upper crust through weakening zones between the diapirs. Our geodynamic model also suggests an asymmetry of structures between the upper and middle-lower crust, with the dome-like granitoids overlying high-grade sedimentary synforms and high-grade diapirs underlying low-grade greenstone belts. Full article