Formation of nanocrystalline γ-ZrH in Zr-Nb alloy: Crystal structure and twinning.

In the present work, the lattice parameter and the twins of γ-ZrH hydride in Zr-2.5Nb-1Si were characterized using high resolution electron microscopy. The lattice parameters of γ-ZrH (P42/mmc, Zr2H2 unit cell) is determined to be a = 0.336 nm, c = 0.508 nm. Twinning γ-ZrH hydride ({011}<01̅1> type) is for the first time reported in zirconium alloys, whose orientation relationship with α-Zr is [100]γ-twins // [12̅10]α and (011)γ-twins // (0002)α. The formation process of γ-ZrH twins is also discussed based on a 'grow-in' mechanism during the transformation from α-Zr to γ-ZrH hydride.

Positive psychological suggestions improve the self-efficacy, social functioning and mood of patients undergoing replantation.

OBJECTIVES: This study aimed to investigate the effect of positive psychological suggestions on self-efficacy and social functioning of patients undergoing replantation. METHODS: The clinical data of 80 patients treated with replantation in our hospital were retrospectively selected and divided into two groups according to the different intervention methods. The control group (n=40) received conventional healthcare interventions, and the study group (n=40) received additionally positive psychological suggestions. The changes of self-efficacy, quality of life and moods were compared between the two groups before intervention, as well as at 7 d, 15 d, 30 d and 60 d after intervention. The effect of positive psychological suggestions on the incidence of complications and satisfaction rate of nursing intervention was also analyzed. RESULTS: At 15 d, 30 d and 60 d after intervention, patients in the study group had higher self-efficacy scores, lower scores of the Social Functioning Deficit Scale as well as lower scores of Self-Rating Anxiety Scale and Self-Rating Depression Scale than those in the control group (P<0.05). The total scores of social support in the study group were higher than those in the control group 60 d after intervention (P<0.05). In addition, the SL-90 scale scores in the study group were lower than those in the control group 60 d after intervention (P<0.05). CONCLUSIONS: Positive psychological suggestions could improve the self-efficacy, social functioning and mood of patients undergoing replantation.

Comparative Study of Microstructural Characteristics and Hardness of ß-Quenched Zr702 and Zr-2.5Nb Alloys.

In this study, two commercial Zr alloys (Zr702 and Zr-2.5Nb) were subjected to the same ß-quenching treatment (water cooling after annealing at 1000 °C for 10 min). Their microstructural characteristics and hardness before and after the heat treatment were well characterized and compared by electron channel contrast (ECC) imaging, electron backscatter diffraction (EBSD) techniques, and microhardness measurements. Results show that after the ß quenching, prior equiaxed grains in Zr702 are transformed into Widmanstätten plate structures (the average width ~0.8 µm) with many fine precipitates distributed along their boundaries, while the initial dual-phase (α + ß) microstructure in Zr-2.5Nb is fully replaced by fine twinned martensitic plates (the average width ~0.31 µm). Differences in alloying elements (especially Nb) between Zr702 and Zr-2.5Nb are demonstrated to play a key role in determining their phase transformation behaviors during the ß quenching. Analyses on crystallographic orientations show that the Burgers orientation relationship is well obeyed in both the alloys with misorientation angles between α plates essentially focused on ~60°. After ß quenching, the hardnesses of both alloys were increased by ~35%-40%. Quantitative analyses using the Hall-Petch equation suggest that such an increase was mainly attributable to phase transformation-induced grain refinements. Since Nb is able to effectively refine the ß-quenched structures, a higher hardness increment is produced in Zr-2.5Nb than in Zr702.

Regulating Precipitates by Simple Cold Deformations to Strengthen Mg Alloys: A Review.

Regulating precipitates is still an important issue in the development of high-strength Mg alloys, due to it determining the precipitation hardening effect. Cold deformation, as a simple and low-cost method, can remarkably influence the precipitate features. It is found that pre-cold deformation before aging can be utilized to enhance the precipitation hardening effect of Mg alloys. Moreover, post-deformation after aging could be an effective method to regulate precipitation orientation. In this review, recent research on the regulation of precipitation behavior by cold deformation in Mg-Al, Mg-Zn, and Mg-RE (RE: rare-earth elements) alloy systems was critically reviewed. The changes in precipitate features and mechanical properties of peak-aged Mg alloys via cold deformation were summarized. The corresponding strengthening mechanisms were also discussed. Finally, further research directions in this field were proposed.

[Experimental study of tissue-engineered skin loaded with keratinocyte growth factor nanocapsules for skin defect].

OBJECTIVE: To study the effect of tissue-engineered skin loaded with keratinocyte growth factor (KGF) nanocapsules for skin defect on athymic mice. METHODS: The acellular dermal matrix (ADM) loaded with KGF-ADM was constructed by means of phacoemulsification solvent evaporation and low temperature drying. The human epidermal stem cells and fibroblasts were captured and identified, then cultivated on the surface of the KGF-ADM. The cell growth was observed. The tissue-engineered skin without KGF was used as sham group. The autogenous skin graft was used as control group. 2 and 6 weeks after the skin was transplanted to the back of athymic mice, the contraction and histological healing of the transplanted skins were observed respectively. Then the immunofluorescence examination with anti-human K10-FITC and beta1-integrin-Cy3 were applied to detect the origin, growth and differentiation of epidermal and dermal cells in tissue-engineered skin. RESULTS: The epidermal stem cells grew well and attached tightly on KGF-ADM. There were small round stem cells and polygonal terminally-differentiated cells, which appeared a partly cloning growth and a tendency of merging. The tissue-engineered skin with KGF nanocapsules gained better result in repairing the skin defects as compared with the blank group and the control group 2 and 6 weeks after transplantation. The regenerative skin cells could connect and mix closely with the athymic mouse skin cells on the border of skin defect. Meanwhile, the regenerative skin existed some contraction. The histological observation with HE staining showed that the regenerative skin possessed intact epidermis with several cell layers and normal keratose stratum, among which there were still some beta1-integrin (+) cells which represented epidermal stem cells or transient amplifying cells when they were tested by immunofluorescence after 6 weeks of transplantation. CONCLUSIONS: The tissue-engineered skin loaded with KGF nanocapsules had a better result in repairing athymic mice skin defects than common tissue-engineered skin without KGF nanocapsules or skin auto-graft.

A comparative study on two kinds of surgical procedures of penile corpora cavernosa augmentation.

OBJECTIVE: Penile augmentation surgery is still a controversial issue because of the uncertain indication, the possibility of severe complications and a variety of surgical techniques. The purpose of this study is to provide two surgical procedures of penile corpora cavernosa augmentation and to investigate its effect by implanting autogenous saphenous vein grafts or expanded polytetrafluoroethylene (ePTFE) vessel patches. METHODS: Between January 2001 and December 2005, 20 patients underwent surgeries in which bilateral longitudinal incisions were placed on the tunica albuginea and the penile corpora cavernosa were extended by means of implantation of saphenous grafts or PTFE artificial vessel patches. The patients included in this study presented either with congenital idiopathic micropenis or normal penile length and perimeter (dysmorphophobia). Before the operation, the penile length and perimeter in the flaccid and erectile states were as follows: flaccid length 2.5-7.5 cm and flaccid perimeter 3.0-7.5 cm; erectile length 4.9-10.5 cm and erectile perimeter 4.5-10.0 cm. RESULTS: Immediately after surgery, the penile corpus circumferential measurements (on table), showed remarkable increases which were 1.0-2.3 cm and 1.5-3.0 cm in the flaccid and erectile states, respectively; then, at 12 months to 5 years' follow-up, these girth gains had reduced by 0.5-1 cm in some cases. All cases in the two groups obtained satisfactory surgical results with satisfactory erection and no serious complications, such as infection and fistula. In 20 cases, 17 married cases resumed regular and satisfactory sexual activities 1 month after the operation without any functional limitation. CONCLUSION: The two kinds of surgical procedures for augmenting penile corpora cavernosa were proved to be effective and reliable, with few complications. Both saphenous grafts and ePTFE artificial vessel patches are excellent materials for reconstructing the tunica albuginea. These augmenting phalloplasties can not only be used for patients with micropenis, but also applied to satisfy the cosmetic and functional requests of patients with normal penile length and perimeter. However, the long-term outcomes of these surgical procedures need a further, detailed follow-up study.

[Fast reconstruction of composite tissue-engineered skin in vitro].

OBJECTIVE: To find a feasible method that can reconstruct the composite tissue-engineered skin fast in vitro and can provide enough skin as soon as possible for covering the surface of the large-area burn. METHODS: The foreskin was taken during the posthectomy. The epidermal cells and fibroblasts were isolated, identified and cultured. The cytokeratin 19 (K19) flow cytometry and the fluorescein isothiocyanate (FITC)-immunofluorescence for K19 and the FITC-immunofluorescence for PAN-cytokeratin of the epidermal cells and the FITC-immunofluorescence for vimentin of the fibroblasts were performed to identify the epidermal cells and the fibroblasts. Then, the epidermal cells were seeded onto the papillary surface of an acellular dermal matrix (ADM) and were submerged into the condition culture medium added with 25 ng/ml of the keratinocyte growth factor (KGF). However, in the control group, no KGF was added. After 24 hours, the ADM was moved up to the air-fluid surface, and the culture was continued. After 6 days, the fibroblasts were seeded onto the other surface of the ADM. After a 24-hour culture, the ADM was harvested and fixed in formalin, and the hematoxylin-eosin staining was conducted. Then, the structure of the reconstructed skin was observed under the microscope and the cell count in the epidermal layer was also conducted. RESULTS: All the cultured and expanded epidermal cells stained by the immunofluorescence demonstrated a positive reaction for PAN-FITC, and a partially positive for K19-FITC, and 17% of the cells demonstrated a positive reaction for K19 identified by the flow cytometry. The fibroblasts could be expanded by more than 100 times after a 7-day culture in vitro, and they could demonstrate a positive reaction for vimentin-FITC. After a 7-day culture, a composite tissue-engineered skin could be attained. The hematoxylin-eosin staining of the reconstructed skin showed that there was one continuous layer of the epidermis on the papillary surface of the ADM and there were fibroblasts in the superficial layer of the other one, but the epidermal layer did not stick tightly to the ADM. The cell count demonstrated that KGF promoted the epidermal cells to proliferate better (P<0.01) and to form more significantly continuous layers of the epidermis in the experimental group than in the control group (P < 0.01). CONCLUSION: Through the seed-cell separation by the digestion of collagenase and trypsin combined with the use of the KGF-added condition culture medium, a composite tissue-engineered skin can be reconstructed within 7 days.