Physicochemical properties of selected root and tuber starches and characterization of extruded, chemically modified corn starches

The physicochemical properties of normal potato, waxy potato, yam and sweet potato starches were examined and compared. Normal potato and waxy potato starches displayed the B-type x-ray diffraction pattern, whereas yam and sweet potato displayed the CA- and C-type, respectively. X-ray diffraction patterns of Naegeli dextrins of normal potato and waxy potato remained the B-type, but those of yam and sweet potato changed to the A-type. 31P-NMR showed the phosphorus contents of the starches to be primarily phosphate monoesters with no detectable phospholipid in any of the four starches. Normal potato and waxy potato starches displayed lower proportions (13 and 14.8%, respectively) of short branch chains of chain length dp 6--12 than did yam and sweet potato starches (17.1 and 19.0%, respectively). Normal potato displayed a larger proportion of long branch chains than did waxy potato amylopectin;A series of cross-linked hydroxypropylated corn starches were extruded. Extrusion process variables including moisture, barrel temperature, and screw design were investigated. Rapid Visco Analyzer pasting profiles of extruded starches displayed different hot paste viscosity and final viscosity depending on extrusion parameters. Increasing starch moisture content during extrusion and level of cross-linking increased starch viscosity (p \u3c 0.0001). Whereas, increasing extrusion temperature and shear decreased starch viscosity (p \u3c 0.0001);Scanning electron microscopy (SEM) of extruded starches showed a gel phase with distorted granules and granule fragments after extrusion at 60°C whereas after extrusion at 100°C only a gel phase was seen. High performance size exclusion chromatography showed extruded starches degraded to different extents, depending on extrusion conditions. The average molecular weight of the amylopectin of unextruded native corn starch was 7.7 x 10 8. Extrusion at 30% moisture, 100°C, and high shear reduced the molecular weight of amylopectin to 1.0 x 108. With the addition of cross-linking, the amylopectin fraction of the extruded starches was less degraded than those of their native and hydroxypropylated corn starch counterparts. Similarly, increasing moisture content during extrusion lowered amylopectin degradation in the extruded starches. The glass transition temperatures of the starches were found to influence amylopectin degradation

Fabrication of antibiotic-loaded dissolvable calcium sulfate beads: an in vitro mixing lab utilizing various antibiotic mixing formulas.

Chronic periprosthetic joint infection (PJI) is a devastating complication that requires an aggressive eradication protocol. Local antimicrobial delivery via dissolvable calcium sulfate (CaSO 4 ) using small-sized beads (3-8 mm) has been utilized as an adjunctive treatment combined with implant exchange, radical debridement, and antimicrobial loaded acrylic spacers. The non-exothermic setting of CaSO 4 theoretically allows for any antimicrobial agent to be used, so long as mixing methods provide a consistent fabrication within a reasonable set time. This study performed the first in vitro mixing study, in which various antimicrobial agents, used singularly and in combination, were mixed with a synthetic CaSO 4 product to observe and document their interactions. The study was performed in a simulated operating room environment. We report a standard mix formula with set times, testing 22 different antimicrobial agents, combinations, and doses. For some antimicrobials and combinations, set times using the standard formula were either too fast or exceedingly slow. For these 14 antimicrobial agents and combinations, we were able to arrive at individualized mixing methods. We present all mixing formulas and set times. In all, we were able to establish mixing methods that incorporate all antimicrobial agents and combinations that we have seen utilized via surgeon-directed use

Early Shear Failure of a 3-Peg Modified Dome Patellar Implant.

Patellar failure in total knee arthroplasty is a major source of complications postoperatively. Previous patellar failure reports commonly cited dissociations of modular and metal-backed patellar implants. However, mechanical breakage of monoblock all-polyethylene patellar implants is very rare. We present a case of an early shear failure of a 3-peg modified dome all-polyethylene patellar implant at 16 months. The patient underwent a revision procedure and at 1-year follow-up, the patients patella and knee remained stable with no reported issues. Shear failure of polyethylene pegs requires excess cyclic shear stress imparted at the prosthetic-bone interface. Patellar implants with a cone design are more constrained and, if misaligned relative to the metallic trochlea, may impart excess shear force to the patella during flexion

Principal reasons for default and impact of financial structure of distressed real estate

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1990.Includes bibliographical references (leaves 89-90).by Edward Norbert McPherson.M.S

Stress-Induced, Aseptic Osteolysis of the Mid-Tibia in a Revision Hinged Total Knee Arthroplasty Mimicking Infection.

In this report, we present the case of an 80-year-old female with pain located over the tip of her cemented tibial stem in a revision hinge total knee arthroplasty with localized osteolysis that looked suspicious for infection. A thorough workup was negative for infection. We postulate that the osteolysis at the end of her tibial stem was initiated by a modulus of elasticity mismatch at the stem tip, which generated a focal area of increased sagittal bone bending and microparticle generation. She was treated with lesional exploration, debridement, synthetic bone grafting, and tibial plating to distribute stress loads away from the tibial stem tip. Histologic analysis identified no organisms or neoplasm. Her pain ultimately resolved, and the patient returned to her customary activities

Biphasic bone graft substitute in revision total hip arthroplasty with significant acetabular bone defects : a retrospective analysis.

AIMS: Large acetabular bone defects encountered in revision total hip arthroplasty (THA) are challenging to restore. Metal constructs for structural support are combined with bone graft materials for restoration. Autograft is restricted due to limited volume, and allogenic grafts have downsides including cost, availability, and operative processing. Bone graft substitutes (BGS) are an attractive alternative if they can demonstrate positive remodelling. One potential product is a biphasic injectable mixture (Cerament) that combines a fast-resorbing material (calcium sulphate) with the highly osteoconductive material hydroxyapatite. This study reviews the application of this biomaterial in large acetabular defects. METHODS: We performed a retrospective review at a single institution of patients undergoing revision THA by a single surgeon. We identified 49 consecutive patients with large acetabular defects where the biphasic BGS was applied, with no other products added to the BGS. After placement of metallic acetabular implants, the BGS was injected into the remaining bone defects surrounding the new implants. Patients were followed and monitored for functional outcome scores, implant fixation, radiological graft site remodelling, and revision failures. RESULTS: Mean follow-up was 39.5 months (36 to 71), with a significant improvement in post-revision function compared to preoperative function. Graft site remodelling was rated radiologically as moderate in 31 hips (63%) and strong in 12 hips (24%). There were no cases of complete graft site dissolution. No acetabular loosening was identified. None of the patients developed clinically significant heterotopic ossification. There were twelve reoperations: six patients developed post-revision infections, three experienced dislocations, two sustained periprosthetic femur fractures, and one subject had femoral component aseptic loosening. CONCLUSION: Our series reports bone defect restoration with the sole use of a biphasic injectable BGS in the periacetabular region. We did not observe significant graft dissolution. We emphasize that successful graft site remodelling requires meticulous recipient site preparation.Cite this article: Bone Jt Open 2022;3(12):991-997

Correction of Femoral Acetabular Impingement at the Time of Primary THA

Background: Primary total hip arthroplasty (THA) is considered one of the most cost effective and functionally beneficial procedures to treat end-stage coxarthrosis worldwide. However, in all regions of the world, there is a small percentage of patients that are plagued by residual anterior hip pain and have limited hip flexion. One explanation for this problem is bone and soft tissue impingement in the anterior hip region. In the native hip, the problem is described as femoral acetabular impingement (FAI). FAI is a form of developmental dysplasia of the hip (DDH). Not infrequently, these dysplastic acetabula are also retroverted. In primary THA, a retroverted boney acetabulum adversely affects prosthetic hip function. Specifically, when the acetabular cup is inserted in an anteverted position and the native acetabulum is retroverted, the proximal femur will still impinge upon the retroverted acetabular bone with flexion and internal rotation. This causes mechanical instability, pain, and prosthetic subluxation. We aptly name this condition prosthetic femoral acetabular impingement (PFAI). Methods: In this study we address PFAI with an anterior acetabular bone wall reduction (AABWR). In a consecutive series of 426 primary THA’s, we prospectively removed all impinging anterior retroverted bone during the THA procedure. All acetabular cups were placed between 25-35 degrees of anteversion. Retroverted acetabular bone extending beyond the acetabular cup was removed along with impinging capsular tissues. All femoral stems were positioned between 15-20 degrees. Results: The study group consisted of 426 THA’s. Three hundred patients (70%) had an AABWR. There were 140 females (47%) and 160 males (53%). The average amount of bone resected in the AABWR group was 1.32 cm (0.3 cm to 3.4 cm). For females, the average bone resection measured 1.1 cm (0.3 to 2.0 cm). For males, the average bone resection measured 1.53 cm (0.3 cm to 3.4 cm). Harris Hip Scores (HHS) at minimum of 1 year follow-up (range 1 to 11.5 years) averaged 91 (64 to 100) for the entire group. In the AABWR group, HHS averaged 92 (71 to 100). Average hip flexion was 110 degrees (100 to 130 degrees). In the non-AABWR group, HHS averaged 87 (71 to 100). Average flexion was 109 degrees (88 to 125 degrees). In the AABWR group, 12 patients (4%) experienced groin pain symptoms. On a scale from 0 to 4, the peak groin pain rating was 1 in 10 of the 12 patients and the remaining 2 rated his/her pain at a 2. As time progressed, 50% of these patients saw their groin pain resolve. In the non-AABWR group, 2 patients (1.6%) experienced groin pain and both patients rated his/her pain at a 1. Discussion: Maximizing hip flexion and function for the active patient undergoing primary THA requires meticulous surgical technique. PFAI may be one reason for unexplained anterior hip pain in the highly active patient that demands higher hip flexion and rotation. Our experience shows that the anterior acetabular rim and part of the anterior column can be removed at the time of primary THA without compromising the THA procedure. The AABWR is now an integral part of our primary THA technique

The Development Of An Interactive Industry/Academic Power Engineering Education Program At The University Of Missouri-Rolla

This paper describes the development of a unique andinno-vative program in power engineering education enhanced through an Industry/Academic interrelationship. This program is devoted to both the teaching and the practice of power engineering. The development of the Industry/Academic relationship and its value as a model for power engineering education are related. A summary of present and proposed future activities concludes the report. Copyright © 1978 by The Institute of Electrical and Electronics Engineers, Inc