Pulsed Nd:YAG laser cutting of NiTi shape memory alloys—Influence of process parameters

Shape memory alloys (SMAs), in particular Nitinol (NiTi), are of increasing interest in research and industry due to their outstanding properties, e.g. the shape memory effect (SME) and high biocompatibility. Obviously, it is necessary to machine these elements from NiTi sheet materials using suitable processing methods that provide high precision and retain the shape memory effect. Pulsed Nd:YAG laser cutting of 1 mm thick NiTi shape memory alloys for medical applications (SMA-implants) has been investigated. Due to the local energy input only small heat-affected zones (HAZ) occur and the shape memory properties remain. The influence of key parameters like pulse energy, pulse width, and spot overlap on the cut geometry, roughness and HAZ is shown.     

Coatings against corrosion and microbial adhesion

A systematic study on anti‐corrosion and anti‐fouling effect of hydrophobic Langmuir–Blodgett and self‐assembled molecular layers deposited on metal surfaces, as well as anti‐microbial adhesion properties of coatings with biocide is presented. Both types of efficiencies produced by LB films are enhanced by Fe³⁺ ions built in the molecular film. The quaternary ammonium type biocide embedded into the cross‐linked gelatin decreased significantly the microbial adhesion, the biofilm formation.     

Full-Scale Tests of Seismic Cable Restrainer Retrofits for Simply Supported Bridges

Many parts of the central and southeastern United States have recently begun initiating seismic retrofit programs for bridges on major interstate highways. One of the most common retrofit strategies is to provide cable restrainers at the intermediate hinges and abutments in order to reduce the likelihood of collapse due to unseating. To evaluate the force-displacement behavior of the cable restrainer retrofits, a full-scale bridge setup was constructed based on an existing multispan, simply supported steel girder bridge in Tennessee, that has been considered for seismic retrofit using cable restrainers. Seismic cable restrainers were connected to the bridge pier using steel bent plates, angles, and undercut anchors embedded in the concrete as specified by typical bridge retrofit plans. The full-scale bridge model was subjected to monotonic loading to test the capacity of the cable restrainer system and to determine the modes of failure. The results showed that the primary modes of failure are in the connection elements of the pier and girders, and they occur at force levels much lower than the strength of the cable. Modifications to the connection elements were designed and tested. The new connections resulted in a higher strength and deformation capacity of the cable restrainer assembly.     

Optimierung eines laserunterstützten Wickelverfahrens für thermoplastische Prepregrovings mit Hilfe der statistischen Versuchsmethodik

Forschung im Ingenieurwesen - Mit Hilfe der statistischen Versuchsmethodik wird der laserunterstützte Wickelprozeß kohlenstoffaserverstärkter thermoplastischer Prepregrovings...     

A Novel Nanoprobe for Multimodal Imaging Is Effectively Incorporated into Human Melanoma Metastatic Cell Lines

To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T₁ relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/μL of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe.     

A constipation scoring system to simplify evaluation and management of constipated patients

PURPOSE: Constipation is a common complaint; however, clinical presentation varies with each individual. The aim of this study was to assess a standard scoring system for evaluation of constipated patients. MATERIALS AND METHODS: All consecutive patients with idiopathic constipation who were referred for anorectal physiologic testing were assessed. A subjective constipation score was calculated based on a detailed questionnaire that included over 100 constipation-related symptoms. Based on the questionnaire, scores ranged from 0 to 30, with 0 indicating normal and 30 indicating severe constipation. The constipation score was then compared with the objective findings of the physiology tests, which include colonic transit time (CTT), anal manometry (AM), cinedefecography (CD), and electromyography (EMG). Colonic inertia was defined as diffuse marker delay on CTT without evidence of paradoxical contraction on AM, CD, or EMG. Pelvic outlet obstruction was defined as paradoxical puborectalis contraction, rectal prolapse or rectoanal intussusception, rectocele, or sigmoidocele. RESULTS: A total of 232 patients (185 females and 47 males) of a mean age of 64.9 (range, 14-92) years were evaluated. All patients had a score of more than 15; on evaluation of the significance of different symptoms in the constipation score with the Pearson's linear correlation test, 8 of 18 factors were identified as significant (P < 0.05). These factors included frequency of bowel movements, painful evacuation, incomplete evacuation, abdominal pain, length of time per attempt, assistance for evacuation, unsuccessful attempts for evacuation per 24 hours, and duration of constipation. All 232 patients had objective obstruction attributable to one or more of the following causes: paradoxical puborectalis contraction (81), significant rectocele or sigmoidocele (48), rectoanal intussusception (64), and rectal prolapse (9). CONCLUSION: The proposed constipation scoring system correlated well with objective physiologic findings in constipated patients to allow uniformity in assessment of the severity of constipation.