Improved biosynthesis of silver nanoparticles using keratinase from Stenotrophomonas maltophilia R13: reaction optimization, structural characterization, and biomedical activity.

In the present study, keratinase from Stenotrophomonas maltophilia R13 was used for the first time as a reducing agent for the eco-friendly synthesis of AgNPs. The keratinase produced by strain R13 was responsible for the reduction of silver ions and the subsequent formation of AgNPs. Maximum AgNP synthesis was achieved using 2 mM AgNO3 at pH 9 and 40 °C. Electron microscopy and dynamic light scattering analysis showed AgNPs were spherical and of average diameter ~ 8.4 nm. X-ray diffraction revealed that AgNPs were crystalline. FTIR indicated AgNPs were stabilized by proteins present in the crude enzyme solution of strain R13. AgNPs exhibited a broad antimicrobial spectrum against several pathogenic microorganisms, and the antimicrobial mechanism appeared to involve structural deformation of cells resulting in membrane leakage and subsequent lysis. AgNPs also displayed 1,1-diphenyl-2-picrylhydrazyl (IC50 = 0.0112 mg/ml), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate radical scavenging (IC50 = 0.0243 mg/ml), and anti-collagenase (IC50 = 23.5 mg/ml) activities.

Numerical Investigations of Interactions between the Knee-Thigh-Hip Complex with Vehicle Interior Structures.

Although biomechanical studies on the knee-thigh-hip (KTH) complex have been extensive, interactions between the KTH and various vehicular interior design parameters in frontal automotive crashes for newer models have not been reported in the open literature to the best of our knowledge. A 3D finite element (FE) model of a 50(th) percentile male KTH complex, which includes explicit representations of the iliac wing, acetabulum, pubic rami, sacrum, articular cartilage, femoral head, femoral neck, femoral condyles, patella, and patella tendon, has been developed to simulate injuries such as fracture of the patella, femoral neck, acetabulum, and pubic rami of the KTH complex. Model results compared favorably against regional component test data including a three-point bending test of the femur, axial loading of the isolated knee-patella, axial loading of the KTH complex, axial loading of the femoral head, and lateral loading of the isolated pelvis. The model was further integrated into a Wayne State University upper torso model and validated against data obtained from whole body sled tests. The model was validated against these experimental data over a range of impact speeds, impactor masses and boundary conditions. Using Design Of Experiment (DOE) methods based on Taguchi's approach and the developed FE model of the whole body, including the KTH complex, eight vehicular interior design parameters, namely the load limiter force, seat belt elongation, pretensioner inlet amount, knee-knee bolster distance, knee bolster angle, knee bolster stiffness, toe board angle and impact speed, each with either two or three design levels, were simulated to predict their respective effects on the potential of KTH injury in frontal impacts. Simulation results proposed best design levels for vehicular interior design parameters to reduce the injury potential of the KTH complex due to frontal automotive crashes. This study is limited by the fact that prediction of bony fracture was based on an element elimination method available in the LS-DYNA code. No validation study was conducted to determine if this method is suitable when simulating fractures of biological tissues. More work is still needed to further validate the FE model of the KTH complex to increase its reliability in the assessment of various impact loading conditions associated with vehicular crash scenarios.