Computational elements based on coupled VO2 oscillators via tunable thermal triggering.

Computational technologies based on coupled oscillators are of great interest for energy efficient computing. A key to developing such technologies is the tunable control of the interaction among oscillators which today is accomplished by additional electronic components. Here we show that the synchronization of closely spaced vanadium dioxide (VO2) oscillators can be controlled via a simple thermal triggering element that itself is formed from VO2. The net energy consumed by the oscillators is lower during thermal coupling compared with the situation where they are oscillating independently. As the size of the oscillator shrinks from 6 µm to 200 nm both the energy efficiency and the oscillator frequency increases. Based on such oscillators with active tuning, we demonstrate AND, NAND, and NOR logic gates and various firing patterns that mimic the behavior of spiking neurons. Our findings demonstrate an innovative approach towards computational techniques based on networks of thermally coupled oscillators.

Construction of a vascularized fascia-prosthesis compound model with axial pedicle for ear reconstruction surgery.

Background: To design a vascular pedicled fascia-prosthesis compound model that can be used for ear reconstruction surgery. Methods: A vascularized tissue engineering chamber model was constructed in New Zealand rabbits, and fresh tissues were obtained after 4 weeks. The histomorphology and vascularization of the newly born tissue compound were analyzed and evaluated by tissue staining and Micro-CT scanning. Results: The neoplastic fibrous tissue formed in the vascularized tissue engineering chamber with the introduction of abdominal superficial vessels, similar to normal fascia, was superior to the control group in terms of vascularization, vascular density, total vascular volume, and total vascular volume/total tissue volume. Conclusion: In vivo, introducing abdominal superficial vessels in the tissue engineering chamber prepped for ear prosthesis may form a well-vascularized pedicled fascia-prosthesis compound that can be used for ear reconstruction.

Experimental study of negative pressure wound therapy combined with platelet-rich fibrin for bone-exposed wounds.

Aim: To evaluate the efficacy of negative pressure wound therapy (NPWT) combined with platelet-rich fibrin (PRF) in treating bone-exposed wounds and explore its possible mechanism. Materials & methods: A bone-exposed wound was created in a total of 32 healthy Sprague-Dawley rats, which were divided into either control group, NPWT group, PRF group or both (N + P group). The bone-exposed area, skin contraction rate and granulation coverage and the level of growth factors in granulation tissue were determined on days 4, 7 and 10. Results: The N + P group showed significantly higher wound closure rate than that achieved with others respectively. Four factors were significantly higher in N + P group than in the other three groups. Conclusion: Combination of NPWT and PRF can repair bone-exposed wounds effectively and accelerate wound healing.

Lay abstract Wounds with exposed bone are refractory, and are usually caused by mechanical trauma, burns, infections, pressure ulcers, diabetic illness and tumor resection. Surgery is the most effective way to cover such wounds. However, repairing defects with local or distal skin flaps can cause potential donor site damage. Skin grafting might be a simpler method, but the avascular interface of bone makes granulation tissue difficult to grow, thus transplanting skin on exposed bones is contraindicated. There is growing interest in identifying alternative treatment strategies. In this study, our goal is to use platelet-derived fibrin in combination with negative pressure wound therapy (NPWT) to determine whether this combined strategy can achieve mesenchymal healing with granulation tissue to treat bone-exposed wounds. The results of wound healing in the NPWT and platelet-rich fibrin combined treatment group were better than those of other treatment groups. The combined treatment strategy of platelet-derived fibrin and NPWT can repair bone-exposed wounds effectively, accelerate wound healing and is a promising therapeutic option for bone-exposed wounds.

Creating Cartilage in Tissue-Engineered Chamber Using Platelet-Rich Plasma Without Cell Culture.

Background: Clinically available cartilage, such as large-volume tissue-engineered cartilage, is urgently required for various clinical applications. Tissue engineering chamber (TEC) models are a promising organ-level strategy for efficient enlargement of cells or tissues within the chamber. The conventional TEC technology is not suitable for cartilage culture, because it lacks the necessary chondrogenic growth factor, which is present in platelet-rich plasma (PRP). In this study, we added autogenous auricular cartilage fragments mixed with PRP in a TEC to obtain a large amount of engineered cartilage. Experiment: To prove the efficacy of this method, 48 New Zealand white rabbits were randomly divided into 4 groups: PRP, vascularized (Ves), PRP, PRP+Ves, and control. Auricular cartilage was harvested from the rabbits, cut into fragments (2 mm), and then injected into TECs. Cartilage constructs were harvested at week 8, and construct volumes were measured. Histological morphology, immunochemical staining, and mechanical strength were evaluated. Results: At week 8, PRP+Ves constructs developed a white, cartilage-like appearance. The volume of cartilage increased by 600% the original volume from 0.30 to 1.8 ± 0.1789 mL. Histological staining showed proliferation of edge chondrocytes in the embedded cartilage in the PRP and PRP+Ves groups. Furthermore, the cartilage constructs in the PRP+Ves group show mechanical characteristics similar to those of normal cartilage. Conclusions: Auricular cartilage fragments mixed with PRP and vascularization of the TEC showed a significantly increased cartilage tissue volume after 8 weeks of incubation in rabbits. Impact Statement Repair of defects of ear cartilage tissue has always been a huge challenge to plastic surgeons. In this article, a new method is presented to produce within 8 weeks auricular cartilage in a tissue engineering chamber without cell culture. Having such a method is a valuable step toward creating a large volume of functional cartilage tissue, which may lead to successful construction of normal auricular structure with minimal donor-site morbidity.

[Study on the use of haemoglobin denaturation test as an alternative to Draize eye irritation test].

OBJECTIVE: To use haemoglobin denaturation test (HD test) as an alternative to Draize eye irritation test (Draize test). METHODS: Fourteen cosmetic ingredients were tested by HD test. The results were compared with two kinds of scores in Draize test, i.e. Maximum average Draize total score (MAS) and Score of 24 h after application (S24). RESULTS: The correlation coefficient between RDC50 and MAS and that between RDC50 and S24 were 0.926 and 0.921 respectively, while that between 1%lambdamax and MAS, and between 1%lambdamax and S24 were 0.881 and 0.791 respectively. The results showed that RDC50 had a higher correlation with Draize test than 1%lambdamax did, but in the use of RDC50 some information of data would be lost. On the other hand, 1%lambdamax, which had a greater correlation with corneal score in the three component scores of the Draize test, could be used for assessing water-insoluble chemicals. CONCLUSION: The results showed that HD test could be used as an effective alternative to Draize eye irritation test.

[Study on using the hen's egg test-chorioallantoic membrane as an alternative method of draize eye irritation test].

OBJECTIVE: To establish and study the hen's egg test-chorioallantoic membrane (HET-CAM) as an alternative method of Draize eye irritation test (Draize test). METHODS: 14 cosmetic ingredients were tested by the Hen's egg test-chorioallantoic membrane score (HET-CAM score) and the chorioallantoic membrane-trypan blue staining (CAM-TB) methods. RESULTS: Showed that compared with two kinds of scores in Draize test, i.e. Maximum average Draize total score (MAS) and score of 24 h after application (S24), the correlation coefficient between HET-CAM score and MAS or S24 was 0.847 or 0.779, while that between CAB-TB and MAS or S24 was 0.862 or 0.831 respectively. The results also showed that CAM-TB had a higher correlation with Draize test than HET-CAM score, partly because it is objective and quantitative. Also, the results showed that HET-CAM score had the greatest correlation with conjunctivae score of the three components, and so did the CAM-TB with corneal score. CONCLUSION: It is suggested that the two types of HET-CAM can be used in a combined manner as an effective alternative method to Draize test.