Role of carbon nanotube dispersion in fracture toughening of plasma sprayed aluminum oxide-carbon nanotube nanocomposite coating

Aluminum oxide (Al2O3, or alumina) is a conventional ceramic known for applications such as wear resistant coatings, thermal liners, heaters, crucibles, dielectric systems, etc. However applications of Al 2O3 are limited owing to its inherent brittleness. Due to its excellent mechanical properties and bending strength, carbon nanotubes (CNT) is an ideal reinforcement for Al2O3 matrix to improve its fracture toughness. The role of CNT dispersion in the fracture toughening of the plasma sprayed Al2O3-CNT nanocomposite coating is discussed in the current work. Pretreatment of powder feedstock is required for dispersing CNTs in the matrix. Four coatings namely spray dried Al2O 3 (A-SD), Al2O3 blended with 4wt.% CNT (A4C-B), composite spray dried Al2O3-4wt.% CNT (A4C-SD) and composite spray dried A1203-8wt.% CNT (A8C-SD), are synthesized by plasma spraying. Owing to extreme temperatures and velocities involved in the plasma spraying of ceramics, retention of CNTs in the resulting coatings necessitates optimizing plasma processing parameters using an inflight particle diagnostic sensor. A bimodal microstructure was obtained in the matrix that consists of fully melted and resolidified structure and solid state sintered structure. CNTs are retained both in the fully melted region and solid-state sintered regions of processed coatings. Fracture toughness of A-SD, A4C-B, A4C-SD and A8C-SD coatings was 3.22, 3.86, 4.60 and 5.04 MPa m1/2 respectively. This affirms the improvement of fracture toughness from 20% (in A4C-B coating) to 43% (in A4C-SD coating) when compared to the A-SD coating because of the CNT dispersion. Fracture toughness improvement from 43% (in A4C-SD) to 57% (in A8C-SD) coating is evinced because of the CNT content. Reinforcement by CNTs is described by its bridging, anchoring, hook formation, impact alignment, fusion with splat, and mesh formation. The Al2O3/CNT interface is critical in assisting the stress transfer and utilizing excellent mechanical properties of CNTs. Mathematical and computational modeling using ab-initio principle is applied to understand the wetting behavior at the Al2O 3/CNT interface. Contrasting storage modulus was obtained by nanoindentation (∼210, 250, 250-350 and 325-420 GPa in A-SD, A4C-B, A4C-SD, and A8C-SD coatings respectively) depicting the toughening associated with CNT content and dispersion.

Non-Contact Femoral Fracture in a Collegiate Football Player

We present a unique athletic injury witnessed by the primary investigator who was compelled to convey the details of the incident to other Certified Athletic Trainers. This case is presented to increase awareness and ensure proper recognition, evaluation, and treatment of this potentially life-threatening injury.

Displaced Comminuted Patellar Fracture Associated with Post Anterior Cruciate Ligament Reconstruction in a Male Collegiate Basketball Player

We present a unique case of a collegiate athlete who suffered an anterior cruciate ligament (ACL) injury leading to a displaced patellar stress fracture. We identified an unusual potential association between ACL reconstruction and patellar fractures in order to avoid potential complications in the rehabilitation and return to activity process.

Coracoid Process Fracture in a High School Football Player

We presented a unique case of a high school athlete who suffered from a coracoid process fracture following a collision with an opposing player. This fracture is commonly misdiagnosed as a clavicular fracture or AC joint sprain. Initial radiographic examination may fail to identify the fracture site. Understanding the clinical features of this injury is an important prerequisite to its overall management. Any misdiagnosis or alteration from the appropriate course of treatment can inhibit return to play and may be avoided by using indicated diagnostic evaluation tools.

Prolonged Rehabilitation of Jones Fracture in Division I-A Collegiate American Football Player: A Case Report

Objective: To describe the prolonged rehabilitation program for a Jones fracture in a Division I-A American football player. Background: A 21 year old, African American, collegiate football player (body mass= 264 lb; height= 76.5 in; body fat= 16.0%) complained of a sharp pain at the dorsal aspect of the left foot. The athlete experiences a compressive force to the fifth metatarsal and upon evaluation, mild swelling was present along the lateral aspect of the foot. Differential Diagnosis: Jones fracture, metatarsal fracture, bone contusion. Treatment: An intramedullary fixation surgery was scheduled two weeks post injury, to correct and stabilize the fracture. Intramedullary fixation is a method of mending the bone internally with a screw, wire, or metal plate along the fractured bone length wise. Following surgery the athlete continued use of crutches for ambulation and was placed in a removable walking boot for 5 weeks. Uniqueness: This case presented a unique challenge in the rehabilitation program, as the athlete experienced slow formation of the bone callus and therefore a prolonged rate of recovery. The athlete was in a walking boot longer than expected (2 weeks longer than anticipated) which inhibited advancement in his rehabilitation due to a slow bone callus formation. A soft callus usually begins to form at day 5 following injury, but documentation was incomplete, and a hypothesis for slow bone callus formation could be secondary to lengthened time between injury occurrence and injury reporting. The athlete may have been weight bearing during the early callus formation, but healing may have been prohibited. Also, vascularization in the area is already limited and may also have played a role in delayed bone growth. Conclusions: Although the return to participation was longer than expected, the rehabilitation program was successful in returning the athlete to competition.

Analysis of fractured terrain using remote sensing and geographic information systems : establishing a correlation between fracture network properties and vegetation

This research analyzed the spatial relationship between a mega-scale fracture network and the occurrence of vegetation in an arid region. High-resolution aerial photographs of Arches National Park, Utah were used for digital image processing. Four sets of large-scale joints were digitized from the rectified color photograph in order to characterize the geospatial properties of the fracture network with the aid of a Geographic Information System. An unsupervised landcover classification was carried out to identify the spatial distribution of vegetation on the fractured outcrop. Results of this study confirm that the WNW-ESE alignment of vegetation is dominantly controlled by the spatial distribution of the systematic joint set, which in turn parallels the regional fold axis. This research provides insight into the spatial heterogeneity inherent to fracture networks, as well as the effects of jointing on the distribution of surface vegetation in desert environments.

Nursing case management : a new perspective to caring for patients with hip fracture

Nursing Case Management has motivated nurses to examine the effects of care provided to patients, and to devise means of improving this care. The success of this nursing care delivery model is well documented among a variety of acute and chronically ill patients. Utilizing nonparametric ANOVA for comparison of two means, this study investigates the outcome of the implementation of a nursingcase management model on an orthopedic unit of a local hospital. A convenience sample (N=149) of hip-fracture patients for two separate eight months charting periods were used. The first period was pre-case management and the second period was after the implementation of nursing managed care on the unit. Results suggested that nursing case management was effective in reducing the total length of hospital stay and post-operative days significantly.

Role of carbon nanotube dispersion in fracture toughening of plasma sprayed aluminum oxide - carbon nanotube nanocomposite coating

Aluminum oxide (A1203, or alumina) is a conventional ceramic known for applications such as wear resistant coatings, thermal liners, heaters, crucibles, dielectric systems, etc. However applications of A1203 are limited owing to its inherent brittleness. Due to its excellent mechanical properties and bending strength, carbon nanotubes (CNT) is an ideal reinforcement for A1203 matrix to improve its fracture toughness. The role of CNT dispersion in the fracture toughening of the plasma sprayed A1203-CNT nanocomposite coating is discussed in the current work. Pretreatment of powder feedstock is required for dispersing CNTs in the matrix. Four coatings namely spray dried A1203 (A-SD), A1203 blended with 4wt.% CNT (A4C-B), composite spray dried A1203-4wt.% CNT (A4C-SD) and composite spray dried A1203-8wt.% CNT (A8CSD), are synthesized by plasma spraying. Owing to extreme temperatures and velocities involved in the plasma spraying of ceramics, retention of CNTs in the resulting coatings necessitates optimizing plasma processing parameters using an inflight particle diagnostic sensor. A bimodal microstructure was obtained in the matrix that consists of fully melted and resolidified structure and solid state sintered structure. CNTs are retained both in the fully melted region and solid-state sintered regions of processed coatings. Fracture toughness of A-SD, A4C-B, A4C-SD and A8C-SD coatings was 3.22, 3.86, 4.60 and 5.04 MPa m1/2 respectively. This affirms the improvement of fracture toughness from 20 % (in A4C-B coating) to 43% (in A4C-SD coating) when compared to the A-SD coating because of the CNT dispersion. Fracture toughness improvement from 43 % (in A4C-SD) to 57% (in A8C-SD) coating is evinced because of the CNT content. Reinforcement by CNTs is described by its bridging, anchoring, hook formation, impact alignment, fusion with splat, and mesh formation. The A1203/CNT interface is critical in assisting the stress transfer and utilizing excellent mechanical properties of CNTs. Mathematical and computational modeling using ab-initio principle is applied to understand the wetting behavior at the A1203/CNTinterface. Contrasting storage modulus was obtained by nanoindentation (~ 210, 250, 250-350 and 325-420 GPa in A-SD, A4C-B, A4C-SD, and A8C-SD coatings respectively) depicting the toughening associated with CNT content and dispersion.