Enhanced autotrophic astaxanthin production from Haematococcus pluvialis under high temperature via heat stress-driven Haber-Weiss reaction.

High temperatures (30-36 °C) inhibited astaxanthin accumulation in Haematococcus pluvialis under photoautotrophic conditions. The depression of carotenogenesis was primarily attributed to excess intracellular less reactive oxygen species (LROS; O2 (-) and H2O2) levels generated under high temperature conditions. Here, we show that the heat stress-driven inefficient astaxanthin production was improved by accelerating the iron-catalyzed Haber-Weiss reaction to convert LROS into more reactive oxygen species (MROS; O2 and OH·), thereby facilitating lipid peroxidation. As a result, during 18 days of photoautotrophic induction, the astaxanthin concentration of cells cultured in high temperatures in the presence of iron (450 µM) was dramatically increased by 75 % (30 °C) and 133 % (36 °C) compared to that of cells exposed to heat stress alone. The heat stress-driven Haber-Weiss reaction will be useful for economically producing astaxanthin by reducing energy cost and enhancing photoautotrophic astaxanthin production, particularly outdoors utilizing natural solar radiation including heat and light for photo-induction of H. pluvialis.

The effect of a "push-pull" structure on the turn-on fluorescence of photochromic thio-ketone type diarylethenes.

a series of diarylethene compounds with a thiophene bridging unit have been synthesized to investigate the relationship between molecular structure and photochromic properties. In particular, the fluorescence properties related to compound 1 were investigated. The results showed that a six-membered ring carrying an electron-donating sulfur atom and an electron-withdrawing carbonyl group is necessary to form a "push-pull" system for the fluorescence of 1.

Experience with sandwich liner and its high rate of failure.

BACKGROUND: Composite ceramic with polyethylene backing was introduced to enhance the quality of ceramic articulation, but the liner's high rate of ceramic fracture has brought serious concern. In this study, the authors investigated the failure rate of sandwich liner in long-term follow-up patients at single institution. METHODS: In this series, we retrospectively reviewed 134 patients (143 hips), and six patients (6.2%) were found to have liner fracture. They were compared to nonfracture patients to identify the associating factors. General patient characteristics were obtained through review of charts. All patients were implanted with SPH Contact acetabular cup and sandwich liner. Function (Harris hip score) and activity (Devane score) were recorded preoperatively and at final follow-up. Radiologically, inclination and abduction angles were measured for comparison. RESULTS: The study did not show any statistical differences between fracture and nonfracture groups in age, weight or body mass index. Side, type of stem used and radiologic parameters were not also significantly different. The operation had significantly improved function and activity postoperatively in both groups, but no statistical significance was noted between the two groups exception to preoperative Harris hip score. On inspection, retrieved ceramic heads and liners showed substantial metal transfer on their surfaces, and linear wears were evident on the ceramic heads. CONCLUSIONS: Compared to other studies, our series also experienced high rate of sandwich liner fracture. Though its use was generally discontinued, it is worrisome to note that failure rate of the liner will substantially increase over time.

Primary Total Hip Arthroplasty Using Third Generation Ceramic-Ceramic Articulation: Results after a Minimum of Three-years of Follow-up.

PURPOSE: This study assessed the short term clinicoradiological results of primary total hip arthroplasty using third generation ceramic-ceramic articulation Accolade TMZF femoral stems. MATERIALS AND METHODS: Two hundred and seventy two patients (294 hips) with primary total hip arthroplasty using third generation ceramic-ceramic articulation Accolade TMZF femoral stems who had been followed-up for a minimum of 3 years were included. Clinicoradiological results were analyzed and postoperative complications were observed. RESULTS: At final follow-up, mean Harris hip score was increased from 52 to 94 points. On radiogical evaluation, the average acetabular inclination was 42 degrees and the average acetabular anteversion was 15 degrees. Neither osteolysis nor loosening were observed around the acetabulum or proximal femur. Among 294 acetabular cups, 293 cups (99.66%) achieved stable fixation. Regarding the 294 femoral stems, 286 (97.28%) had bony fixation, 7 (2.38%) had fibrous fixation, and none were found to have unstable stem fixation. Proximal bone resorption was observed in 17 hips (5.78%; only Grade 1) and radiolucent lines were observed in 88 hips (29.93%), however, all were around the distal smooth portion of the stems. Postoperative complications included dislocation in 6 hips (2.04%), heterotopic ossification in 3 hips (1.02%), ceramic fractures in 4 hips (1.36%), superficial infection in 1 hip (0.34%), and squeaking in 8 hips (2.72%). CONCLUSION: The short term clinicoradiological results of primary total hip arthroplasty using third generation ceramic-ceramic articulation and Accolade TMZF femoral stems together with Secur-Fit acetabular cups were satisfactory. However, problems such as ceramic fractures and squeaking after arthroplasty were observed. Additional studies are necessary in order to develop methods that may reduce or eliminate these complications.

Fracture-dissociation of ceramic liner.

The use of BIOLOX delta ceramic (CeramTec AG, Plochingen, Germany) has been increasing. This ceramic prevents cracking by restraining the phase transformation due to the insertion of nano-sized, yttria-stabilized tetragonal zirconia into the alumina matrix. This restrains the progress of cracking through the formation of platelet-like crystal or whiskers due to the addition of an oxide additive. We observed a case of BIOLOX delta ceramic liner (CeramTec AG) rim fracture 4 months postoperatively. Radiographs showed that the ceramic liner was subluxated from the acetabular cup. Scratches on the acetabular cup and femoral neck were seen, and the fracture was visible on the rim of the liner. Under electron microscope, metal particle coatings from the ceramic liner were identified. The ceramic liner, fracture fragments, and adjacent tissues were removed and replaced with a ceramic liner and femoral head of the same size and design. We believe the mechanism of the fracture-dissociation of the ceramic liner in this case is similar to a case of separation of the ceramic liner from the polyethylene shell in a sandwich-type ceramic-ceramic joint. To prevent ceramic liner fracture-dissociation, the diameter of the femoral neck needs to be decreased in a new design, while the diameter of the femoral head needs to be increased to ensure an increase in range of motion.

Ceramic failure after total hip arthroplasty with an alumina-on-alumina bearing.

BACKGROUND: The mechanical properties of alumina ceramic, now in its third generation, have been markedly improved through the evolution of design features and manufacturing processes and the introduction of proof-testing. Nonetheless, because of the lack of ductility of alumina ceramic, there is concern regarding the risk of fracture during insertion or in vivo use. The purpose of the present study was to present a multicenter review of primary total hip arthroplasties performed with use of a polyethylene-ceramic composite liner combined with a ceramic femoral head, with particular attention to failure of the ceramic bearing. METHODS: We evaluated 357 primary total hip arthroplasties that had been performed in 319 patients with use of a contemporary alumina-on-alumina bearing design incorporating a polyethylene-ceramic composite liner within a titanium-alloy shell coupled with a 28-mm-diameter ceramic femoral head. The procedures were performed at four participating centers from 1998 to 2001. Ceramic failure without trauma occurred in six hips (1.7%). All of these hips were revised, and the retrieved alumina implants were examined by means of visual inspection and scanning electron microscopy equipped with energy-dispersive x-ray spectrometry. RESULTS: Two femoral heads fractured during the first postoperative year, and four alumina liners fractured after an average of 36.8 months in vivo. All four of the explanted alumina liners revealed evidence of rim contact with the metal neck of the femoral component. Composition analysis confirmed that surface-stain materials were titanium particles transferred from the femoral component. CONCLUSIONS: Despite the theoretical improvement in the fracture toughness of a polyethylene-alumina composite liner, a relatively high rate of catastrophic ceramic bearing surface failure was still observed at the time of short-term follow-up. This finding prompted us to discontinue the use of this type of alumina bearing design.