Distinct Valley Polarization in Vertical Heterobilayers: Difference between Edge- and Center-Nucleated WS2/MoS2.

Structural imperfections can cause both beneficial and detrimental consequences on the excitonic characteristics of transition metal dichalcogenides (TMDs). Regarding valley selection, structural defects typically promote valley depolarization in monolayer TMDs, but defect healing via an additional growth process can restore valley polarization in vertical heterobilayers (VHs). In this study, we analyzed the valley polarization of center-nucleated and edge-nucleated VHs (WS2/MoS2) grown using a controlled growth process and discovered that defect-related photoluminescence (PL) is strongly suppressed in the center-nucleated VHs due to defect healing. Additionally, we demonstrated that the valley polarization of lower-lying intralayer excitons is more sensitive to the defect density of the sample than to higher-lying intralayer excitons. Despite defect healing in the center-nucleated VHs, the temperature-dependent PL study indicated that valley depolarization of the lower-lying intralayer excitons becomes significant below 100 K because of stronger hybridization of defect states. Also, we conducted a comprehensive study on the excitation intensity dependence to investigate the electron-doping-induced Auger recombination mechanism, which also contributes to valley depolarization of intralayer excitons via regeneration of intervalley trions. Our findings provide valuable insight into the development of VH-based valleytronic devices.

Thickness-dependent in-plane anisotropy of GaTe phonons.

Gallium Telluride (GaTe), a layered material with monoclinic crystal structure, has recently attracted a lot of attention due to its unique physical properties and potential applications for angle-resolved photonics and electronics, where optical anisotropies are important. Despite a few reports on the in-plane anisotropies of GaTe, a comprehensive understanding of them remained unsatisfactory to date. In this work, we investigated thickness-dependent in-plane anisotropies of the 13 Raman-active modes and one Raman-inactive mode of GaTe by using angle-resolved polarized Raman spectroscopy, under both parallel and perpendicular polarization configurations in the spectral range from 20 to 300 cm-1. Raman modes of GaTe revealed distinctly different thickness-dependent anisotropies in parallel polarization configuration while nearly unchanged for the perpendicular configuration. Especially, three Ag modes at 40.2 ([Formula: see text]), 152.5 ([Formula: see text]), and 283.8 ([Formula: see text]) cm-1 exhibited an evident variation in anisotropic behavior as decreasing thickness down to 9 nm. The observed anisotropies were thoroughly explained by adopting the calculated interference effect and the semiclassical complex Raman tensor analysis.

Customized tissue engineering for ear reconstruction.

Tissue engineering (TE) of cartilage for reconstructive surgery has proven to be a promising option for obtaining tissue for 3D structures that results in minimal donor site morbidity. Technological advances in this area are important since many defects can only be treated with customized implants. Most TE strategies rely on the use of resorbable 3D scaffolds to guide the growing tissue, with each tissue requiring a specific scaffold that has precisely defined properties depending on the physiological environment. Rapid prototyping (RP) technologies allow the fabrication of scaffolds of various geometric complexities from a variety of materials and as composites, while even allowing the inner architecture of the object to be varied in a defined manner at any given location. Scaffolds can be manufactured using RP techniques directly from computer aided design (CAD) data sources, e.g. via an STL file. The combination of TE and RP serves as the basis for the production of customized implants, for example the cartilage ear framework, and provides new perspectives for autologous ear reconstruction.

Effectiveness of free gracilis muscle flaps in the treatment of chronic osteomyelitis with purulent fistulas at the distal third of the tibia in children.

BACKGROUND: Chronic purulent infection at the distal third of the tibia resulting from of a previous hematogenous osteomyelitis in children is a severe infection which is seldom reported in the literature and remains a difficult challenge for orthopaedic surgeons. METHODS: A 6-year retrospective review from September 2001 to October 2006 (institutional review board-approved) was performed to evaluate postoperative surgical results of this type of infection using a free gracilis muscle flap. RESULTS: A total of 6 children with an average age of 9.8 years were included. The infective period of purulent fistulas ranged from 6 to 31 months (mean 17.7). Staphylococcus aureus were reported in all wounds (6/6) and were commonly combined with Escherichia coli (5/6). All of the free gracilis muscle transfers were successful (6/6 flaps). No postoperative recurrence of infection was observed with an average postoperative follow-up period of 3 years. All patients were also able to satisfactorily demonstrate walking and standing functions. CONCLUSIONS: Both the radical debridement of infected tissues and restoration of ample blood supply using free muscle flaps are the keys to success. Based on its favorable form, the free gracilis muscle flap can be considered a suitable muscle for use in reconstruction. LEVEL OF EVIDENCE: IV.

Successful re-construction of a large tissue defect using a free pre-fabricated flap with purely implanted arterialised venous loop.

Flap pre-fabrication represents an interesting technique in tissue-defect reconstruction. In this article we report the successful clinical application of a free pre-fabricated flap using an isolated arterialised venous loop as an implanted vascular pedicle for reconstruction of an extended soft-tissue defect on the leg, as well as clinical neo-vascularisation development following arterialised venous loop implantation. The procedure appears potentially useful in selected patients due to the easy harvest of an isolated vein loop as well as a favourable functional and aesthetic result at the donor site.

Neovascularization and free microsurgical transfer of in vitro cartilage-engineered constructs.

Cartilage tissue engineering shows to have tremendous potential for the reconstruction of three-dimensional cartilage defects. To ensure survival, shape, and function, in vitro cartilage-engineered constructs must be revascularized. This article presents an effective method for neovascularization and free microsurgical transfer of these in vitro constructs. Twelve female Chinchilla Bastard rabbits were used. Cartilage-engineered constructs were created by isolating chondrocytes from auricular biopsies, amplifying in monolayer culture, and then seeding them onto polycaprolactone scaffolds. In each prefabricated skin flap, three in vitro cartilage-engineered constructs (2 x 2 x 0.5 cm) and one construct without cells (served as the control) were implanted beneath an 8 x 15 cm random-pattern skin flap, neovascularized by implantation of an arteriovenous vascular pedicle with maximal blood flow. Six weeks later, the neovascularized flaps with embedded cartilage-engineered constructs were completely removed based on the newly implanted vascular pedicle, and then freely retransferred into position using microsurgery. Macroscopic observation, selective microangiography, histology, and immunohistochemistry were performed to determine the construct vitality, neovascularization, and new cartilage formation. The results showed that all neovascularized skin flaps with embedded constructs were successfully free-transferred as free flaps. The implanted constructs were well integrated and protected within the flap. All constructs were well neovascularized and showed histologically stability in both size and form. Immunohistology showed the existence of cartilage-like tissue with extracellular matrix neosynthesis.

Influence of silicone sheets on microvascular anastomosis.

The use of silicone products combined with free flap transfer is well established in reconstructive surgery. We determined the risk of thrombosis as a result of direct contact between the silicone sheet and the point of microanastomosis. We performed microvascular surgery in 24 female Chinchilla Bastard rabbits weighing 3500 to 4000 g using two groups: Group 1 (n = 12), microanastomosis directly in contact with silicone sheets; and Group 2 (n = 12), microanastomosis protected by a 2 x 3 x 1-cm muscle cuff before being placed in contact with the silicone. We assessed flow-through of the microanastomosis by selective microangiography and histology at 1 and 3 weeks. All microanastomoses in Group 1 were occluded by postoperative thromboses, whereas all microanastomoses in Group 2 had adequate flow-through. Histologic analysis revealed thromboses in Group 1 formed from collagenous bundles of fiber securely attached to the intraluminal wall of the vessel. Three weeks after the procedure, these thromboses were canalized by varying small vessels. In Group 2, a slight luminal stenosis with evidence of infiltration of inflammatory cells at the microanastomosis line was observed histologically in all cases. Prefabricated flaps using silicone sheets and muscular cuffs placed around the anastomoses appear to reduce the risk of thrombosis and enhance neovascularization.

Microsurgical finger replantation in Hanoi, Vietnam: our first experience.

In this retrospective study, the author reports on preliminary results of finger replantations performed in the Department of Traumatology, Orthopaedics and Hand Surgery at Central Hospital 108, No. 1 Tran Hung Dao, Hanoi, Vietnam between September 1999 and December 2002. Forty-six amputated digits involving thirty-two complete and fourteen incomplete fingers were replanted and subsequently evaluated. The majority of the amputations was caused by avulsing or crushing injuries (76 %), with the left hand being predominantly affected (78.3 %). The overall success rate of finger replantation was 91.3 %. Secondary supplemental operations were performed in 8/42 (19 %) of the surviving digits, including seven tenolyses and one repeated osteosynthesis. The combined postoperative functional outcomes rated either as "good" or "fair" were 90.5 %, based on an average follow-up period of 18 months. One surviving replant was amputated one year later due to lost function and paraesthesia. We concluded from the study that digit replantations, especially multiple amputations, are often successful and it is always worthwhile to attempt to restore function as well as the normal appearance of the hand and digits. Despite the limited postoperative movement and less than normal level of sensation compared to uninjured counterparts, most individuals with surviving replanted digits following amputations can actively and effectively perform normal tasks without instability or pain.