Investigating Microstructural Evolution and Its Influence on Tribological Behaviors of In-Situ Formed VCp Reinforced Iron-Based Composites with Variable Mn Content.

In this work, we fabricated VCp-reinforced iron-based composites (VCFCs) by adjusting the amount of Mn elements and investigated how the concentration of Mn affected the microstructural characteristics of Vanadium carbide (VC) and the texture of the iron matrix, and the influence of microstructure on tribological behaviors should be investigated. We demonstrated that VC changed from thick dendrite crystals (~50 µm) to tiny equiaxed crystals (~5 µm). Furthermore, the nucleation mechanism of VC also transformed from homogeneous nucleation to heterogeneous nucleation due to the lower Gibbs free energy of TiC and the tailoring effect of the Mn elements. In addition, γ-Fe in the FCC structure gradually increased and ascribed an increase of Mn content to the lower transformation temperature of martensite. Furtherly, particulate features and phase constitution could contribute to hardness and wear resistance. Higher hardness and excellent wear resistance occurred in the 3.0 Mn sample, which had a hardness of 869 HV and a wear rate of 1.77 × 10-6 mm3/(N·m). In addition, the adhesive wear could be the main wear mechanism in the 3.0 Mn sample, while the abrasive wear could be in the 4.5 Mn sample.

Varicose vein on right tibia, post-traumatic varicose ulcer, and bone exposure: A case report.

Varicose ulcer, a severe symptom of chronic venous insufficiency, may be refractory to treatment when accompanied by bone exposure. The lack of a blood supply and fresh granulation tissue on the exposed bone can result in a protracted healing time. A 59-year-old man suffered from varicose veins for 10 years, a varicose ulcer for 1 year, and an exposed right tibia for 40 days after using traditional Chinese medicinal plasters. The patient was treated with conventional high ligation and stripping of the great saphenous vein, segmental endovenous laser ablation, bone drilling, and a free skin graft. Patient outcome is satisfactory 2 years after discharge. We present a rare case of varicose ulcer in association with bone exposure. Tibia drilling with Kirschner wire was used to allow blood flow and provide nutrients for the formation of granulation tissue over the exposed bone and wound healing. Subsequently, free skin grafting was used during reconstructive surgery to replace skin loss on the right calf. Physicians encountering this rare condition in clinical practice should consider our treatment approach as a successful limb-preserving option for these patients.

Combination of dexamethasone and Avastin® by supramolecular hydrogel attenuates the inflammatory corneal neovascularization in rat alkali burn model.

Corneal neovascularization (CNV) is one of the leading causes of vision loss and a high-risk factor for transplant rejection. The present study proposed a supramolecular hydrogel comprised of MPEG-PCL micelles and α-cyclodextrin (α-CD) for co-delivery of dexamethasone sodium phosphate (Dexp) and Avastin® (Ava), and further evaluated its therapeutic efficacy in rat alkali burn model. A physical mixing of Dexp/Ava, MPEG-PCL micelles, and α-CD aqueous solution leads to a spontaneous formation of the supramolecular hydrogel via a "host-guest" recognition between MPEG and α-CD. The supramolecular hydrogel provides a relatively quick release of Dexp over Ava during the study of the 5-day in vitro release. The results of in vitro cytotoxicity test and wound healing assay illustrated that the proposed supramolecular hydrogel was non-toxic against L-929 and HCEC cells and did not significantly affect the migration of HCEC cells after 24h incubation. The corneal distribution test suggested that the precorneal duration of Ava was significantly extended by the supramolecular hydrogel with respect to its solution formulation. Moreover, the supramolecular hydrogel showed high ocular biocompatibility and was a non-irritant after topical instillation. Furthermore, the Dexp-Ava hydrogel medication, but not by Ava solution and Ava hydrogel medication, could greatly attenuate the alkali burn-induced corneal inflammation and remarkably suppress the corneal neovascularization via the downregulation of VEGF, CD31, and α-SMA expression in the rat alkali burn model. As a result, the combined Dexp and Ava by supramolecular hydrogel exhibited an advantage over Ava monotherapy approach, which might be a promising alternative therapy for inflammatory CNV.

Cystic adventitial disease of the popliteal artery: report of two cases.

Cystic adventitial disease (CAD) of the popliteal artery is a rare vascular disorder in which a mucin-containing cyst develops in the adventitial layer of the artery. We report two such cases, each of which was treated differently. The first case was of a 49-year-old man, treated by excision of the involved arterial segment and interposition of an autologous saphenous vein graft. The second case was of a 36-year-old man, treated by local excision of the affected arterial segment and interposition with prosthetic bypass grafting. Both patients presented with rapidly progressing intermittent claudication of the lower extremities, but without remarkable evidence of atherosclerotic disease. Physical examination revealed diminished or absent popliteal, posterior tibial and dorsalis pedis pulses in the lower extremities. Color Doppler ultrasound of the popliteal artery revealed hypoechoic cystic lesions surrounding the vessel, and popliteal arterial stenosis, in both patients. Surgery resulted in immediate improvement of the arterial pulse distal to the lesion. Both patients recovered uneventfully. Thus, resection of the involved artery segment and interposition bypass grafting, using either patient or prosthetic veins, offers favorable results for CAD of the popliteal artery.