Scalable Production of Catecholamine-Densified MXene Coatings for Electromagnetic Shielding and Infrared Stealth.

Processing transition metal carbides/nitrides (MXenes) inks into large-area functional coatings expects promising potential for electromagnetic interference (EMI) shielding and infrared stealth. However, the coating performances, especially for scalable fabrication techniques, are greatly constrained by the flake size and stacking manner of MXene. Herein, the large-area production of highly densified and oriented MXene coatings is demonstrated by engineering interfacial interactions of small MXene flakes with catecholamine molecules. The catecholamine molecules can micro-crosslink MXene nanosheets, significantly improving the ink's rheological properties. It favors the shear-induced sheet arrangement and inhibition of structural defects in the blade coating process, making it possible to achieve high orientation and densification of MXene assembly by either large-area coating or patterned printing. Interestingly, the MXene/catecholamine coating exhibits high conductivity of up to 12 247 S cm-1 and ultrahigh specific EMI shielding effectiveness of 2.0 ×10 5  dB cm2 g-1 , obviously superior to most of the reported MXene materials. Furthermore, the regularly assembled structure also endows the MXene coatings with low infrared emissivities for infrared stealth applications. Therefore, MXene/catecholamine coatings with ultraefficient EMI shielding and low infrared emissivity prove the feasibility of applications in aerospace, military, and wearable devices.

[Effect of local basic fibroblast growth factor and 5-fluorouracil on accelerating healing and preventing tendon adhesion after flexor tendon repair].

OBJECTIVE: To assess the effect of basic fibroblast growth factor (bFGF) and 5-fluorouracil (5-FU) applied topically on the tendon adhesion and the healing process after the flexor tendon repair in Leghorn chickens. METHODS: Ninety male Leghorn chickens (weighing 3.0-3.5 kg) were randomly divided into 3 groups, with 30 chickens in each group. The flexor digitorum profundus tendons of the third right toes were transected and sutured directly. The repair site in group A was given 0.6 microL fibrin sealant (FS). In group B, the repair site was given 0.6 microL FS containing 500 ng bFGF. In group C, before the tendons were transected, they had been soaked in 5-FU solution, and then the same treatment as group B was given. Six specimens of the third toe were harvested to perform the macroscopical and histological examinations at 1, 2, 4, and 8 weeks, respectively, and to perform the biomechanical test at 8 weeks. RESULTS: All animals survived until the experiment was completed. All incisions healed smoothly. No rupture occurred in the repaired tendon. At 8 weeks, the adhesion degree was lighter in group C than in group B (P < 0.05), but there was no significant difference in the adhesion degree between group A and groups B, C (P > 0.05). At 1, 2, and 4 weeks after operation, the number of fibroblast cells of group A was significantly less than that of group B (P < 0.05), and the number of fibroblast cells of group C was significantly less than that of group A and group B in the tendon sheath and epitenon (P < 0.05); however, it was significantly more than that of group A in the tendon parenchyma (P < 0.05), and no significant difference was observed when compared with that of group B (P > 0.05). At 8 weeks, no difference was found among 3 groups (P > 0.05). The collagen fiber content of group A was significantly less than that of group B at 4 and 8 weeks (P < 0.05). In the sheath and epitenon, the collagen fiber content of group A was significantly more than that of group C at 4 weeks (P < 0.05); however, no significant difference was found between 2 groups at 8 weeks (P > 0.05). The collagen fiber content of group A was significantly less than that of group C in the parenchyma at 4 and 8 weeks (P < 0.05). At all time points, the collagen fiber content of group B was significantly more than that of group C in the sheath and epitenon (P < 0.05), but no significant difference in the parenchyma was observed between 2 groups (P > 0.05). The biomechanical tests showed that the gliding excursion of the tendon in groups A, B, and C was (3.51 +/- 0.56), (2.84 +/- 0.42), and (4.56 +/- 0.59) mm, respectively; the work of flexion was (14.08 +/- 1.85), (20.62 +/- 3.52), and (10.91 +/- 1.53) N x mm, respectively; and the ultimate tensile strength of the tendon was (11.26 +/- 1.83), (15.02 +/-2.20), and (14.40 +/- 1.57) N, respectively. There were significant differences in the gliding excursion of the tendon and the work of flexion among 3 groups (P < 0.05) and in the ultimate tensile strength of the tendon between group A and groups B, C (P < 0.05), but there was no significant difference in the ultimate tensile strength of the tendon between group B and group C (P > 0.05). CONCLUSION: Local single-use bFGF and 5-FU can not only effectively promote the healing of flexor tendon, but also significantly reduce tendon adhesion.

Functional reconstruction of traumatic loss of flexors in forearm with gastrocnemius myocutaneous flap transfer.

Reconstruction of flexor function of forearm remains a challenge in the reconstructive surgery. With development of microsurgical techniques, reconstructive surgeons have been able to envision muscle transplantation for restoration of function and not simply for provision of soft tissue coverage. In this report, we present our experience in three patients of successful treatment of traumatic flexor loss in the forearm with the microsurgical medial gastrocnemius myocutaneous flap. At 18- to 24-months follow-up, the detected action potential (Latency and Amplity) in the transferred muscle was significantly improved in the EMG examination. The strength of the digital flexion reached to III degree in one case, IV degree in two cases. No complications were noted in the donor legs. We conclude that the microsurgical medial gastrocnemius myocutaneous flap transfer can be an ideal alternative for functional reconstruction of the forearm flexor muscle in three posttrauma patients.

[Cross-bridge vascular anastomosis free tissue transplantation in repairing tissue defects of extremities].

OBJECTIVE: To investigate the application and effect of the cross-bridge vascular anastomosis free flap transplantation for tissue defects of extremities. METHODS: From May 1982 to November 2005, 110 cases of tissue defects of extremities were treated with cross-bridge vascular anastomosis free tissue transplantation. Of 110 patitents, 80 were male and 30 were female with a median age of 30 years(5 to 54 years). Tissue defects were caused by traffic accidents (59 cases), machine injuries (32 cases) and mangled injuries (19 cases). The locations were the forearms in 2 cases and the legs in 108 cases. And 69 cases had simple soft tissue defects, 6 cases had simple bone defects, and 35 cases had complicated defects. The length of bone defect ranged from 5 cm to 19 cm and the area of soft tissue defect ranged from 6 cm x 10 cm to 15 cm x 35 cm. The graft tissue included latissimus dorsi musculocutaneous flap, vastus anterolateral flap,cutaneous fibula flap, osseous fibula flap, and cutaneous iliac flap. The cross-bridge of the two lower extremities was performed in 106 cases, the cross-bridge of the two upper extremities in 2 cases, and the cross-bridge of the upper-lower extremities in 2 cases. The composite tissue transplantation was used if the graft tissues were two or more. The wounds of donor site was directly sutured in 67 cases, and partly sutured with skingrafting in 43 cases. RESULTS: Vascular crisis occurred in 9 cases. Vascular crisis was relieved in 5 cases and grafting tissues was survival after exploring the vessel; 4 cases failed. The graft tissue was survival in 101 cases, and the survival rate was 96.4%. The follow-up time was 4 months to 22 years with an average of 6.3 years. Graft bone healed and mean healing time was 4 months. The flap appearance was satisfactory and extremity function was restored to normal. One case became necrosis in the edge of the flap and cured by debridement, dressing and skingrafting, the other got primary healing at 2-3 weeks after operation. CONCLUSION: The application of the cross-bridge vascular anastomosis free tissue transplantation for tissue defects of extremities is an effective method, when extremities have no vessel anastomosed.

[Effects of exogenous basic fibroblast growth factor on in-sheathed tendon healing and adhesion formation].

OBJECTIVE: To explore the effects of exogenous basic fibroblast growth factor (bFGF) on in-sheathed tendon healing and adhesion formation. METHODS: Ninety Leghorn chickens were randomly divided into 3 groups (groups A, B and C), 30 animals for each group, and the right third digitorum longus tendon of the chicken was transected to make defect models. In group A, the tendon was sutured in situ after transection. In group B, the tendon was sutured after 0.6 microl fibrin sealant (FS) was applied at repair site. In group C, the tendon was sutured after 0.6 microl FS mixed with 500 ng bFGF was applied at repair site. At 1, 2, 4 and 8 weeks after operation, the tendons of 6 chickens in each group were harvested for morphological and histological evaluation. Six specimens of each group was obtained for biomechanical test at 8 weeks. RESULTS: The gross observation showed that the differences of grading of tendon adhesion were not significant between groups A, B, and C 8 weeks after operation (P > 0.05). Histological evaluation showed that there were no significant differences in fibroblast counting and the content of collagen fibers between groups A and B (P > 0.05). The angiogenesis, fibroblast proliferation and collagen production in the sheath, epitendon and parenchyma at repair site in group C occurred earlier and were more than those in groups A and B, showing significant differences (P < 0.05). The biomechanical tests showed that the gliding excursion of the tendon in group A, B and C were 3.44 +/- 0.43, 3.51 +/- 0.56 and 2.84 +/- 0.42 mm respectively; the work of flexion were 14.87 +/- 1.72, 14.08 +/- 1.85 and 20.62 +/- 3.52 Nmm respectively; the ultimate tensile strength of the tendon was 10.34 +/- 1.45, 11.26 +/- 1.83 and 15.02 +/- 2.20 N respectively; showing no significant differences between groups A and B (P > 0.05), but showing significant differences between group C and groups A, B (P < 0.05). CONCLUSION: The exogenous bFGF at tendon repair site can facilitate in-sheathed tendon healing, but also increase the tendon adhesion formation.

Reconstruction of thumb loss complicated by skin defects in the thumb-index web space by combined transplantation of free tissues.

OBJECTIVE: To introduce a new technique of 1-stage reconstruction for thumb loss complicated by thumb-index web space contracture and to report its clinical effectiveness. METHODS: From November 1994 to September 2004 there were 11 patients with thumb loss and contracture in the thumb-index web space who had a combined transplantation of free tissues to reconstruct the missing thumb and to rebuild the web space. The reconstructive procedure used the second toe and the anterolateral thigh flap in 5 patients, the second toe and the scapular flap in 2, the big toe wraparound flap and the anterolateral thigh flap in 3, and the big toe wrapround flap and the scapular flap in 1. The 2 independent free tissues were connected together by a vascular combination to form an assembly with 1 common vascular pedicle, which then was anastomosed to the selected vessels in the recipient hand. In this vascular series the dorsalis pedis artery and the greater saphenous vein served as the common vascular pedicle of the flap transfers and the radial artery and the cephalic vein provided the recipient vessels. The outcomes of the reconstructions were evaluated using the Michigan Hand Outcomes Questionnaire. RESULTS: The flaps survived completely in all patients except 1. In this patient a small area in the distal part of the transplanted anterolateral thigh flap became necrotic but healed after dressing changes without the need for further surgical intervention. A mean follow-up period of 3.6 years showed a mean increase of 4.3 cm in the width of the thumb-index web space and a considerable improvement in overall hand function was noted on the Michigan Hand Outcomes Questionnaire with effect sizes of greater than 3 (large effect) in all domains. CONCLUSIONS: Combined transplantation of the second toe or the big toe wraparound flap and a free skin flap is suitable to reconstruct a missing thumb and repair the associated skin defect in the adjacent thumb-index web space. We found good functional recovery and an acceptable appearance in this series of patients. Type of study/level of evidence: Therapeutic, Level IV. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Spectral analysis of blood perfusion in the free latissimus dorsi myocutaneous flap and in normal skin.

To find the properties in the oscillatory components of the cutaneous blood flow on the successful free flap, a wavelet transform was applied to the laser Doppler flowmetry (LDF) signals which were measured simultaneously on the surfaces of the free latissimus dorsi myocutaneous flap and on the adjacent intact skin of the healthy limb, of 18 patients. The frequency interval from 0.0095 to 1.6 Hz was examined and was divided into five subintervals (I: 0.0095-0.021 Hz; II: 0.021-0.052 Hz; III: 0.052-0.145 Hz; IV: 0.145-0.6 Hz and V: 0.6-1.6 Hz) corresponding to endothelial metabolic, neurogenic, myogenic, respiratory and cardiac origins. The average amplitude and total power in the frequency range 0.0095-1.6 Hz as well as within subintervals I, II, IV and V were significantly lower for signals measured on the free flap than those obtained in the healthy limb. However in interval III, they were significantly higher. The normalized spectral amplitude and power in the free flap were significantly lower in only two intervals, I and II, yet in interval III they were significantly higher; no statistical significance was observed in intervals IV and V. The distinctive finding made in this study, aside from the decrease of endothelial metabolic processes and sympathetic control, was the significant increase of myogenic activity in the free flap. It is hoped that this work will contribute towards knowledge on blood circulation in free flaps and make the monitoring by LDF more reliable.

Application of the cross-bridge microvascular anastomosis when no recipient vessels are available for anastomosis: 85 cases.

The purpose of this article is to introduce the results of free tissue transfers using the technique of the cross-bridge microvascular anastomosis when the recipient lacks suitable vessels for anastomosis. Between May of 1982 and June of 2002, a series of 85 patients underwent this procedure. The transferred tissues were the free latissimus dorsi myocutaneous flap, the free vascularized fibula, the free fibular osteocutaneous flap, and the free iliac osteocutaneous flap, alone or in combination. The donor vessels were the anterior tibial artery and great saphenous vein, the posterior tibial artery and its venae comitantes, and the radial artery and cephalic vein. Good results were achieved. The success rate reached 95.29 percent. The authors believe this procedure can be performed in the event of serious tissue defect where the vessels are unsuitable for anastomosis.