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Osteolysis of prosthesis caused by wear debris is one of the key factors leading to clinical failure of artificial joints. In order to understand the friction， wear and debris characteristics of prosthesis materials and optimize the tribological design of prosthesis， the most commonly used cobalt chromium molybdenum-ultra-high molecular weight polyethylene (CoCrMo-UHMWPE) pair was selected as artificial joint， and neonatal bovine serum solution was used as the lubricant. Subsequently， a 50，000 reciprocating sliding wear experiment was carried out under the point-to-surface contact stresses of 22， 35， 48 and 60 MPa， respectively. The friction coefficient， wear amount and wear morphology of the CoCrMo-UHMWPE pair were studied by multi-functional friction and wear testing machine， metallographic microscope， scanning electron microscope and other instruments， and then its friction and wear characteristics were characterized. Furthermore， the quantity，size， morphology and distribution characteristics of wear debris were studied by acid decomposition method. Results showed that the contact stress had a significant effect on the friction， wear and wear debris characteristics of the CoCrMo-UHMWPE pair. With the gradual increase of contact stress， the friction coefficient of CoCrMo-UHMWPE pair changed little but had a downward trend， the wear amount increased significantly and presented a certain linear relationship， and the wear morphology also showed more serious furrows and scratches. In terms of wear debris characteristics， the increase of contact stress led to a significantly increase of the number of wear debris with a size smaller than 5 μm，but the total amount of wear debris first increased and then decreased. Besides， the typical morphology of wear debris was mainly blocky， accompanied by a small amount of spherical and flaky wear debris of smaller sizes.

Standardization of laboratory animals is the basis for obtaining accurate and stable experimental data, drawing objective and reliable experimental conclusions. The standardization of laboratory animal feeds is an integral part of laboratory animal standardization and an important support to realize laboratory animal standardization. In this paper, we compared the historical process of laboratory animal feeds standardization at home and abroad, outlined the key problems existing in the current domestic work, and put forward targeted countermeasures in order to provide references for the standardization of laboratory animal feeds in China.

The design of effective civil aircraft man-machine interactive airworthiness verification scenarios is the basis for the implementation of crew workload verification. In accordance with the 1523 clauses of CCAR25 of the Civil Aviation Regulations of China and the airworthiness verification requirements in Appendix D,through the interpretation of the airworthiness verification regulations of the transport aircraft crew workload,the workload verification man-machine interactive airworthiness content and verification process is established. Then,the design principles for the crew workload airworthiness verification scenarios of civil aircraft man-machine interaction is established,and the verification scenarios is designed from the four dimensions of test crew,operating process,operating environment and operating status,and then the typical crew workload airworthiness verification scenarios is captured. Finally,the airworthiness verification method of crew workload is proposed combined with crew workload evaluation strategies compared with the measurement methods. The results show that the constructed civil aircraft man-machine interactive airworthiness verification scenarios and airworthiness verification methods are applicable and effective,and can provide a reference for airworthiness verification of civil aircraft crew workload.

BackgroundThe quality of neutron radiographic images is mainly evaluated by human visual system (HVS), but HVS cannot be used as a real-time auxiliary for optimization parameters of neutron imaging systems.PurposeThis study aims to evaluate the quality of neutron radiographic images by no-reference image quality assessment (NR-IQA) and provide an effective approach for the parameters optimization of neutron imaging systems.MethodsFirstly, the plain natural images distorted with different distortion levels and types were labelled with quality scores to construct an experimental dataset by the gradient magnitude similarity deviation (GMSD) method. Then, the residual network (ResNet) model was employed to evaluate the quality of neutron radiographic images without reference images. Finally, the goal of extracting features and assessing the quality of neutron radiographic images was achieved by training the ResNet.ResultsThe model performs well in the test set of the experimental dataset and the quality prediction of the two group authentic neutron radiographic images.ConclusionsThe proposed quality assessment method could be used for the quality prediction of neutron radiographic images.

Objectives The force of a bolt group of a long strip base with multiple sets of equipment under various local loads is different from that of the ordinary localized base to meet the needs of the base design.Methods The procedures and key technology of the finite element method to analyze the force of a bolt group are summarized. Based on the continuous beam theory and the balance of force and moment, a set of approximate simplified calculation methods and formulas is proposed to determine the force of bolts on a strip base of multi-group equipment under local tensile force, transverse bending moment, and longitudinal bending moment and combined loading. The force of the bolt group on a strip base under various local loads was calculated and compared using the proposed method.Results The results showed that the method presented in this paper is simple and accurate, usually slightly larger than the finite element result and tends to be conservative.Conclusions The method proposed can be used in the design of ship equipment bases and strength analysis of ships' support structure.

Bacitracin is a broad-spectrum antibiotics mainly produced by Bacillus, and is used as veterinary medicine in the fields of livestock and poultry breeding. Insufficient supply of precursor amino acids might be an important factor that hinders high-level microbial production of bacitracin. We investigated the effect of strengthening L-cysteine supply on bacitracin production by an industrial bacitracin producer, Bacillus licheniformis DW2. Overexpression of cysK encoding L-cysteine synthase led to a 9.17% increase of the bacitracin titer. Moreover, overexpression of cysE encoding L-serine acetyltransferase and cysP encoding thiosulfate/sulfate intracellular transporter increased the bacitracin titers by 7.23% and 8.52%, respectively. Moreover, overexpression of a putative cystine importer TcyP led to a 29.19% increase of intracellular L-cysteine, and bacitracin titer was increased by 7.79%. Subsequently, the strong promoter PbacA was used to replace the promoters of genes cysP, cysE and tcyP in strain DW2::ysK, respectively. The resulted strain CYS4 (DW2::cysK-PbacA-(cysP)-PbacA(cysE)- PbacA(tcyP) produced 910.02 U/mL bacitracin, which was 21.10% higher than that of the original strain DW2 (747.71 U/mL). Together with the experiments in 3 L fermenters, this research demonstrated that enhancing intracellular L-cysteine supply is an effective strategy to increase bacitracin production of B. licheniformis.

Bacitracin is a broad-spectrum cyclic peptide antibiotic, and mainly produced by Bacillus. Energy metabolism plays as a critical role in high-level production of target metabolites. In this study, Bacillus licheniformis DW2, an industrial strain for bacitracin production, was served as the original strain. First, our results confirmed that elimination of cytochrome bd oxidase branch via deleting gene cydB benefited bacitracin synthesis. Bacitracin titer and ATP content were increased by 10.97% and 22.96%, compared with those of original strain, respectively. Then, strengthening cytochrome aa3 oxidase branch via overexpressing gene qoxA was conducive to bacitracin production. Bacitracin titer and ATP content were increased by 18.97% and 34.00%, respectively. In addition, strengthening ADP synthesis supply is also proven as an effective strategy to promote intracellular ATP accumulation, overexpression of adenosine kinase DcK and adenylate kinase AdK could all improve bacitracin titers, among which, dck overexpression strain showed the better performance, and bacitracin titer was increased by 16.78%. Based on the above individual methods, a method of combining the deletion of gene cydB and overexpression of genes qoxA, dck were used to enhance ATP content of cells to 39.54 nmol/L, increased by 49.32% compared to original strain, and bacitracin titer produced by the final strain DW2-CQD (DW2ΔcydB::qoxA::dck) was 954.25 U/mL, increased by 21.66%. The bacitracin titer produced per cell was 2.11 U/CFU, increased by 11.05%. Collectively, this study demonstrates that improving ATP content was an efficient strategy to improve bacitracin production, and a promising strain B. licheniformis DW2-CQD was attained for industrial production of bacitracin.

Bacitracin is a broad-spectrum polypeptide antibiotic, which is formed by 11 amino acids residues. Precursor amino acids supply might be the limit factor during bacitracin fermentation. First, our results demonstrated that increasing Ile and Leu supplies were regarded as the efficient strategies for the enhanced titer of bacitracin. Then, the amino acid permease YhdG, which was identified as the BCAA permease, was deleted and overexpressed in DW2, respectively. Our results showed that knocking out of permease YhdG could improve bacitracin production remarkablely. The bacitracin titer of the yhdG deficient strain DW2ΔyhdG reached 917.35 U/mL by flask fermentation, increased by 11% compared with that of DW2. In addition, the bacitracin titer was decreased by 25% in the YhdG overexpressed strain. Meanwhile, the intracellular concentrations of BCAA were higher than DW2 during the biosynthesis of bacitracin. The above results suggested that the permease YhdG might act as an exporter for branched chain amino acids in B. licheniformis DW2. Taken together, the increasing intracellular concentrations of branched chain amino acids by deleting amino acid permease YhdG could improve bacitracin titer. This study provided a new strategy for high-level production of bacitracin.

Objective: To observe the efficacy and adverse reaction of the improvement program of cladribine combined with cytarabine (2-CdA+Ara-C) in treatment of children with refractory high-risk Langerhans cell histiocytosis (LCH)., Methods: 13 patients with refractory high-risk LCH or recurrent LCH were treated by combined 2-CdA+Ara-C chemotherapy. The treatment efficacy and the disease state in the process were evaluated according to the Histiocyte Society Evaluation and Treatment Guidelines (2009). The drug toxicity was evaluated according to the Common Terminology Criteria Adverse Events Version 4.0 (CTCAE v4.0, 2009)., Results: Of 13 patients, 10 cases achieved non active disease (NAD); 2 patients with liver cirrhosis before the improvement program with CIP-LCH-2012 gave up the treatment after 1 course of therapy; 1 patient died of infectious shock after chemotherapy with severe pulmonary infection and intestinal infection. All 13 patients had grade 3 of blood and lymphatic system toxicity; 10 patients had grade 1 of hepatobiliary and gastrointestinal side effects; 3 patients with liver cirrhosis before the improvement program had grade 2 or grade 3 of hepatobiliary system and gastrointestinal system side effects, including 1 patient of death., Conclusion: The improvement program of CIP-LCH-2012 had significant efficacy for children with refractory high-risk and relapsed LCH. The cladribine-associated toxicity was of significant myelosuppression, which may be tolerated in the most children patients. The program could be considered as a recommended salvage therapy for multi-system LCH (MS-LCH) after failure of first-line therapy, and as a first-line therapy for MS-LCH with risk organ injury. The program should be used with caution or dose-adjustment consideration for pre-treatment of severe organ damage exist, especially cirrhosis.

Objectives: To study the clinical features and gene mutations of EBV-HLH in Chinese children., Methods: Sixteen pediatric patients with Epstein-Barr virus-associated HLH were enrolled the study from May 2011 to September 2012, who were admitted to Capital Institute of Pediatrics. All patients' clinical features were recorded and their nucleotide sequences of all exons and their flanking intronic sequences of perforin (PRF1) gene, protein unc-13 homolog D (UNC13D) gene, two fusion protein genes of syntaxin 11 (STX11)gene, synaptic binding protein 2 (STXBP2) gene, SH2 domain 1A (SH2D1A) gene, and the X-linked inhibitor of apoptosis protein (XIAP) gene were amplified by PCR followed by direct sequencing. Based on HLH gene detection results, all patients divided into the positive and negative gene EBV-HLH subgroups. Statistical analysis was conducted using SPSS 11.5 software., Results: Seven of sixteen pediatric patients with EBV-HLH were identified with heterozygous, hemizygous, and homozygous mutations in PRF1, UNC13D, STXBP2, and SH2D1A. No significant differences were found on the gender, age, illness duration, EBV load, the positive duration of EBV-DNA, lab results, clinical symptoms, treatment, and the outcome between the HLH gene positive and negative subgroups (P > 0.05)., Conclusions: A considerable EBV-HLH pediatric patients have genetic defects, and HLH gene defects may not affect the clinical features and treatment of EBV-HLH pediatric patients.

Objective: To observe and explore the effects of adipose-derived stem cells (ADSCs)-hyaluronic acid (HA) composite on healing of wound combined with radiation injury., Methods: The ADSCs were harvested from the fat tissue in groin of 10 inbred Sprague Dawley (SD) rats and were isolated and cultured by enzyme digestion. The ADSCs-HA composite was prepared with ADSCs (5 x 10(6) cells/mL) at passage 6 and HA (10 mg/mL). Thirty inbred SD rats, 15 males and 15 females, were randomly divided into groups A (n = 10), B (n = 10), and C (n = 10). A 2 cm x 2 cm full-thickness skin defect was made on the rat back before 20 Gy 60Co radiation exposure. One week after debridement, wounds were treated by petrolatum gauze in group A as the control group, by HA (0.4 mL) and petrolatum gauze in group B, and by ADSCs-HA composite (0.4 mL) and petrolatum gauze in group C. The microvessel density (MVD) and the distribution of CD90 positive cells were observed at 1st, 2nd, 3rd, and 4th weeks., Results: The wound healing was slower, and wound did not heal at 4th week and still filled with granulation tissue in group A; the wound healing of group B was faster than that of group A, and the wound did not heal completely with depression in the center at 4th week; the wound healed completely with epidermilizated surface and no obvious depression at 4th week in group C. The histological observation showed that MVD was significantly higher in group C than in groups A and B at the 1st, 2nd, and 3rd weeks (P < 0.05), and in group B than in group A at the 3rd week (P < 0.05); MVD was significantly higher in groups B and C than in group A (P < 0.05), but no significant difference was found between groups B and C (P > 0.05) at 4th week. No CD90 positive cell was found in groups A and B; CD 90 positive cells were observed in group C and gradually decreased with time., Conclusion: ADSCs-HA composite can accelerate healing of wound combined with radiation injury by promoting and controlling wound angiogenesis.

Objective: To investigate the surgical techniques and effectiveness for reconstruction of severe full-thickness chest wall defects., Methods: Between January 2006 and December 2010, 14 patients with full-thickness chest wall defects were treated, including 12 cases caused by giant chest wall malignant tumor excision, 1 case by thermocompression injury, and 1 case by radiation necrosis. There were 8 males and 6 females with an average age of 42 years (range, 23-65 years). The size of chest wall defects ranged from 8 cm x 5 cm to 26 cm x 14 cm. All patients complicated by rib defect (1-5 ribs), and 3 cases by sternum defect. Thoracic skeleton reconstruction was performed with Vicryl mesh or polytetrafluoroethylene mesh in 10 patients. Other 4 patients did not undergo thoracic skeleton reconstruction. The bilobed skin flaps, pectoralis major myocutaneous flap, latissimus dorsi myocutaneous flap, and rectus abdominis myocutaneous flap were utilized for repairing soft tissue defects. The size of the dissected flaps ranged from 10 cm x 7 cm to 25 cm x 13 cm. The donor sites were sutured directly or were repaired by free skin graft., Results: Poor healing of incision occurred in 2 cases, which was cured after debridement, myocutaneous flap transfer, and skin graft. The other wounds healed by first intention. All patients were followed up 6-36 months (mean, 8 months). No tumor recurrence during follow-up, except 1 patient with osteosarcoma who died of liver metastasis at 6 months after operation. Transient slight paradoxical respiration occurred in 1 patient who did not undergo thoracic skeleton reconstruction at 5 days after operation. Integrity of chest wall in other patients was restored without paradoxical respiration and dyspnea., Conclusion: Depending on the cause, the size, and the location of defect, single or combination flaps could be used to repair soft tissue defect, and thoracic skeleton reconstruction should be performed when defect is severe by means of synthetic materials.

Objective: To introduce the experience and comprehend of application of many kinds of skin flaps in repair of heel skin and soft tissue defect., Methods: From August 1993 to April 2007, 242 cases of skin and soft tissue defect on heel were treated. There were 157 males and 85 females aged 27-76 years. There were 35 cases of unstable scar, 46 cases of chronic ulcer, 57 cases of squamous cell carcinoma, 72 cases of malignant melanoma and 32 cases of injury. The defect area ranged from 2 cm x 2 cm to 8 cm x 14 cm, wound was with low-grade infection in 51 cases. The course of disease was 1 hour to 5 years. The lateral calcaneal flaps (34 cases), the dorsum pedis flaps (15 cases), the medial plantar artery island flaps (108 cases), the sural neurovascular flaps (36 cases), the saphenous neurocutaneous vascular flaps (26 cases) and free (myocutaneous) skin flaps (23 cases) were used to repair heel wounded surface according to specific location of heel wounded surface, range of skin and soft tissue defect. The size of the (myocutaneous) skin flap was 3.0 cm x 2.5 cm to 15.0 cm x 9.0 cm. The donor area was directly sutured or covered with skin grafts., Results: In 242 cases, 235 cases achieved healing by first intention, 5 cases had partial necrosis of flaps, 2 cases had mild infection. The donor area healed by first intention. A total of 217 patients were followed up for 1 month to 60 months. The color of flaps were normal and the texture of flaps were softer than that of normal heel tissue; the flaps were wearable, the shape of flaps were satisfactory. The patients can walk after 6 months of operation, and the gait was normal. In 118 cancer patients, no local tumor recurrence occurred, and distant metastatic lesions were observe in 22 malignant melanoma patients. In 32 cases of malignant melanoma followed up 60 months, no distant metastatic lesions were found., Conclusion: In base of following the primary disease treatment, heel function reconstruction and contour structural feature remodeling, we adopted some kind of island or free (myocutaneous) skin flap can be used to repair heel wound. The ideal effect in heel function reconstruction and contour structural feature remodeling were obtained.

Objective: To introduce the experience and comprehension to reconstruct nasal defect after tumor excision., Methods: From April 1996 to April 2006, based on the aesthetic subunit principle and according to the size, shape, location of nasal defect and the conditions of surrounding skin, homologous local flap was selected to cover the nasal defect in 428 cases which nasal tumors were removed. Among 428 cases, there were 273 men and 155 women, with a median age of 52 years (12-78 years); including 146 cases of basal cell carcinoma, 83 cases of squamous cell carcinoma, 54 cases of epidermal cyst, and 145 cases of pigmented naevus. The clinical stage of malignant tumor was 0-I stage, the course of disease was 1 week to 3 months. The locations were nasal tip in 51 cases, nasal ala in 102 cases, dorsum of nose in 138 cases, and nasal side in 137 cases, across 2 nasal subunits in 83 cases. The area of the defect ranged between 0.6 cm x 0.6 cm and 3.0 cm x 4.0 cm. The origin of flaps was frontonasal flap in 58 cases, bilobed flap in 67 cases, reforming rhomboid flap in 152 cases, nasolabial flap in 118 cases, forehead falp in 33 cases. The secondary defect of donor site was directly sutured., Results: Among 428 cases, 423 cases acquired complete recovery; 3 cases which had epiderm necrosis over the far end of the flap achieved healing by the first intention and 2 cases which had suffered low-grade infection of incision achieved healing by the second intention after regional change dressings. The nasal defect was successfully repaired in all patients, and the all flaps survived. A total of 385 patients were available for follow-up of 1 to 60 months, no tumor recurrence occurred, and the repaired tissue were good match with surrounding tissue, good nasal contour was obtained, the cosmetic results were satisfactory., Conclusion: Based on the nasal aesthetic subunit principle, the local flap can reconstruct the nasal above medial defect, and a good color, contour and texture match with the surrounding skin can be obtained, the cosmetic results are satisfactory.

Objective: To investigate aesthetic outcomes and postoperative complications of hydroxyapatite particulate artificial bone for repairing sunken deformation of frontal bone following removal of dermoid cyst., Methods: From February 2000 to May 2005, hydroxyapatite particulate artificial bone was used to repair the sunken deformation of frontal bone in 13 cases (9 males and 4 females), and the age of the patients was from 17 to 41 years. The dermoid cysts were all found during infant period, and the length and width of the cysts ranged from 6 cm x 4 cm to 10 cm x 8 cm. An incision along the hair-edge or tumor margin was made to excise the dermoid cyst in the forehead. After complete removal of dermoid cyst, the sunken frontal bone was examined and repaired with hydroxyapatite particulate artificial bone. The clinical check-up and X-ray examination were utilized to determine aesthetic outcomes and postoperative complications at 1 week, 1 month and 6 months after operation., Results: The primary wound healing was obtained in all patients postoperatively, and no complications such as hematoma, infection, recurrence of dermoid cysts or displacement of hydroxyapatite particulate artificial bone were observed. With a follow-up from 1 to 20 months, all sunken deformations were completely repaired with satisfactorily aesthetic outcomes. Through clinical check-up and X-ray examination, the implants were found to integrate with the frontal bones without any gaps and displacement., Conclusion: It is a simple and viable method to repair sunken deformation of frontal bone with hydroxyapatite particulate artificial bone.

Objective: To investigate the feature and regularity of the collagen change in bone healing during bone lengthening., Methods: Bone lengthening model was made in the middle segment of the rabbit tibia. Five days after the model was established, the bone was lengthened 1.5 mm per day for 14 days. The rabbits were put to death after elongation, 7, 14, 21, 30, 40, 50, 60 and 70 days after elongation. The distracted area of the bone was imbedded with paraffin. After being stained by the picric acid-sirius red staining, the slice was observed under polarized microscope., Results: The features of the collagen change in the distracted bone were as follows: (1) In the fibrous tissue of the distracted area during lengthening period and the early stage after lengthening, there was not only collagen III but also much collagen I. (2) Collagen I , II and III were observed in the cartilage. (3) Collagen I, II and III were also observed in the pseudo-growth plate. (4) Collagen I took the dominance during lengthening period and the late stage after lengthening., Conclusion: New bone formation in bone lengthening is under the distracted force, so the collagen changes have different features compared with that in fracture healing. Collagen I, II and III can be identified by picric acid-sirius red staining and polarized microscope, so a new method for studying the collagen typing in bone repairing is provided.