► The cyclic softening is intrinsic to tempered martensitic lath/subgrain structure. ► It is due to the decrease of dislocation density and to the subgrain coarsening. ► Optimizing the creep ...resistance do not limit the cyclic softening effect. ► Better initial creep properties lead to correct remaining creep strength after cycling.
The present article compares the cyclic behaviour of various 9–12%Cr steels, both commercial grades and optimized materials (in terms of creep strength). These materials were subjected to high temperature fatigue and creep-fatigue loadings. TEM examinations of the microstructure after cyclic loadings were also carried out. It appears that all the tempered ferritic–martensitic steels suffer from a cyclic softening effect linked to the coarsening of the subgrains and laths and to the decrease of the dislocation density. These changes of the microstructure lead to a drastic loss in creep strength for all the materials under study. However, due to a better precipitation state, several materials optimized for their creep strength still present a good creep resistance after cyclic softening. These results are discussed and compared to the literature in terms of the physical mechanisms responsible for cyclic and creep deformation at the microstructural scale.
Limonene is one of the most important terpenes having wide applications in food and fragrance industries. The epoxide of limonene, limonene oxide, finds important applications as a versatile ...synthetic intermediate in the chemical industry. Therefore, attempts have been made to synthesize limonene oxide using eco-friendly processes because of stringent regulations on its production. In this regard, we have attempted to synthesize it using a cost-effective and eco-friendly process. Chemoenzymatic epoxidation of limonene to limonene oxide was carried out using in situ generation of peroxy octanoic acid from octanoic acid and H2O2. In this study, agricultural-waste rice husk ash (RHA)-derived silica was surface-functionalized using (3-aminopropyl) triethoxysilane (APTS), which was cross-linked using glutaraldehyde for immobilization of Candida antarctica lipase B. Furthermore, the immobilized enzyme was entrapped in calcium alginate beads to avoid enzyme leaching. Thus, limonene oxide was prepared using this catalyst under conventional and microwave heating. The microwave irradiation intensifies the process, reducing the reaction time under the same conditions. Maximum conversion of limonene to limonene oxide of 75.35 ± 0.98% was obtained in 2 h at 50 °C using a microwave power of 50 W. In the absence of microwave irradiation, the conventional heating gave 44.6 ± 1.14% conversion in 12 h. The reaction mechanism was studied using the Lineweaver–Burk plot, which follows a ternary complex mechanism with inhibition due to peroxyoctanoic acid (in other words H2O2). The prepared catalyst shows high reusability and operational stability up to four cycles.
Attention has long focused on the actin cytoskeleton as a unit capable of organizing into ensembles that control cell shape, polarity, migration and the establishment of intercellular contacts that ...support tissue architecture. However, these investigations do not consider observations made over 40 years ago that the actin cytoskeleton directly binds metabolic enzymes, or emerging evidence suggesting that the rearrangement and assembly of the actin cytoskeleton is a major energetic drain. This Review examines recent studies probing how cells adjust their metabolism to provide the energy necessary for cytoskeletal remodeling that occurs during cell migration, epithelial to mesenchymal transitions, and the cellular response to external forces. These studies have revealed that mechanotransduction, cell migration, and epithelial to mesenchymal transitions are accompanied by alterations in glycolysis and oxidative phosphorylation. These metabolic changes provide energy to support the actin cytoskeletal rearrangements necessary to allow cells to assemble the branched actin networks required for cell movement and epithelial to mesenchymal transitions and the large actin bundles necessary for cells to withstand forces. In this Review, we discuss the emerging evidence suggesting that the regulation of these events is highly complex with metabolism affecting the actin cytoskeleton and vice versa.
Heparan sulfates (HSs) modulate tissue elasticity in physiopathological conditions by interacting with various matrix constituents as tropoelastin and elastin-derived peptides. HSs bind also to ...protein moieties accelerating amyloid formation and influencing cytotoxic properties of insoluble fibrils. Interestingly, amyloidogenic polypeptides, despite their supposed pathogenic role, have been recently explored as promising bio-nanomaterials due to their unique and interesting properties. Therefore, we investigated the interactions of HSs, obtained from different sources and exhibiting various degree of sulfation, with synthetic amyloidogenic elastin-like peptides (ELPs), also looking at the effects of these interactions on cell viability and cell behavior using in vitro cultured fibroblasts, as a prototype of mesenchymal cells known to modulate the soft connective tissue environment. Results demonstrate, for the first time, that HSs, with differences depending on their sulfation pattern and chain length, interact with ELPs accelerating aggregation kinetics and amyloid-like fibril formation as well as self-association. Furthermore, these fibrils do not negatively affect fibroblasts' cell growth and parameters of redox balance, and influence cellular adhesion properties. Data provide information for a better understanding of the interactions altering the elastic component in aging and in pathologic conditions and may pave the way for the development of composite matrix-based biomaterials.
Since 2006, the effect of the anti-CD20 antibody rituximab (RTX) in patients with moderate-severe GO has been challenged in several non-controlled studies and, recently, in one randomized controlled ...trial vs placebo and in one vs steroids. We randomized 32 patients to RTX or ivMP and the CAS decreased at 24 weeks more significantly after RTX while 100% of patients improved compared to 69% after ivMP ( P < 0.001). 500 mg RTX was as effective as two doses of 1000 mg. Disease reactivation was never observed in patients after RTX, but in five (31%) after ivMP. There was no change of proptosis, but RTX was more effective on motility and quality of life. Stan and colleagues did not find RTX effective in treating active GO, when compared to placebo. The study was conducted on 21 patients, of whom two, after RTX, developed optic neuropathy. Major differences in this study are a much longer disease duration (11.2 months vs 4.5 months), a greater number of patients previously treated with steroids (40% vs 19%) and less motility involvement (diplopia score 2 vs 3.5). Evidence is also emerging for therapeutic effectiveness even using much lower doses of RTX. We have also been using a single 100 mg dose of RTX in patients with moderate-severe GO and preliminary results show disease inactivation in more than 90% of patients. RTX may be a good alternative to steroids in non responders, as it has a disease modifying effect. RTX administration should be limited for now to experienced Centers.
Introduction: We report a rare case of an aggressive large-cell neuroendocrine lung tumour, which presented with ocular metastasis. Case Presentation: A 70-year-old lady presented with a 4-week ...history of left eye pain and photophobia. Ocular examination revealed left-sided episcleritis and she was treated with topical lubricants and steroids. However, she re-presented 6 months later with recurrent left eye symptoms and was found to have an iris stroma amelanotic lesion, posterior synechiae, 360-degrees rubeosis iridis, raised intraocular pressure, and trace vitreous inflammation. Ultrasound biomicroscopy revealed a left thickened iris with an associated ciliary body lesion. Sarcoid-related ocular inflammation was suspected, but a computed tomography (CT) scan of the lung revealed an incidental right upper lobe lesion. Histology from a transcorneal iris biopsy showed a high-grade neuroendocrine carcinoma, and the diagnosis of metastatic lung large-cell neuroendocrine carcinoma was confirmed via high-resolution CT scan, positron emission tomography scan, and CT-guided lung biopsy. She was given multiple courses of different chemotherapy regimens along with palliative radiotherapy. However, the tumour and its metastases continued to progress and she passed away 4 years after her initial presentation. Conclusion: Ocular metastatic large-cell neuroendocrine carcinoma is rare, and the first presentation with ocular metastasis is even rarer. This case highlights the importance of early detection of ocular metastases in order to hasten oncological treatment. A low threshold for systemic investigations and ophthalmology referral in cases of unexplained, refractory ocular symptomatology is essential, given the heterogeneous presentation, rarity, and poor prognosis of these tumours, even with maximal treatment.
Given a resistor network on
Z
d
with nearest-neighbor conductances, the effective conductance in a finite set with a given boundary condition is the minimum of the Dirichlet energy over functions ...with the prescribed boundary values. For shift-ergodic conductances, linear (Dirichlet) boundary conditions and square boxes, the effective conductance scaled by the volume of the box converges to a deterministic limit as the box-size tends to infinity. Here we prove that, for i.i.d. conductances with a small ellipticity contrast, also a (non-degenerate) central limit theorem holds. The proof is based on the corrector method and the Martingale Central Limit Theorem; a key integrability condition is furnished by the Meyers estimate. More general domains, boundary conditions and ellipticity contrasts will be addressed in a subsequent paper.
Ageing changes in the eye Salvi, S M; Akhtar, S; Currie, Z
Postgraduate Medical Journal,
09/2006, Letnik:
82, Številka:
971
Journal Article, Book Review
Recenzirano
Odprti dostop
Ageing changes occur in all the structures of the eye causing varied effects. This article attempts to review the parameters of what is considered within the “normal limits” of ageing so as to be ...able to distinguish those conditions from true disease processes. Improving understanding of the ageing changes will help understand some of the problems that the ageing population faces.
Epidemiological data indicate that lower urinary tract symptoms (LUTS)/BPH can be associated with metabolic syndrome (MetS). Chronic inflammation has been proposed as a candidate mechanism at the ...crossroad between these two clinical entities.Aim of study is to examine the correlation among pre-operatory LUTS/BPH severity, MetS features and inflammatory infiltrates in prostatectomy specimens.
A total of 271 consecutive men treated with simple prostatectomy were retrospectively selected for this study in two tertiary referral centers for LUTS/BPH. Prostate diameters and volume were measured by transrectal ultrasound, LUTS scored by International Prostate Symptom Score (IPSS) and obstruction by uroflowmetry. The International Diabetes Federation and American Heart Association and the National Heart, Lung and Blood Institute was used to define MetS. The inflammatory infiltrate was investigated combining anatomic location, grade and extent of flogosis into the overall inflammatory score (IS); the glandular disruption (GD) was used as a further marker.
Eighty-six (31.7%) men were affected by MetS. Prostatic volume and anterior-posterior (AP) diameter were positively associated to the number of MetS components. Among MetS determinants, only dyslipidaemia (increased serum triglycerides and reduced serum high-density lipoprotein) was associated with an increased risk of having a prostatic volume >60 cm(3) (hazard ratio (HR) = 3.268, P < 0.001). A significant positive correlation between the presence of MetS and the IS was observed. MetS patients presented lower uroflowmetric parameters as compared with those without MetS (Maximum flow rate (Q(max)): 8.6 vs 10.1, P = 0.008 and average flow rate (Q(ave)): 4.6 vs 5.3, P = 0.033, respectively), and higher obstructive urinary symptoms score (P = 0.064). A positive correlation among both IS-GD and IPSS Score was also observed (adjusted r = 0.172, P = 0.008 and adjusted r = 0.128, P = 0.050).
MetS is associated with prostate volume, prostatic AP diameter and intraprostatic IS. The significantly positive association between MetS and prostatic AP diameter could support the observation that MetS patients presented lower uroflowmetric parameters. In conclusion, MetS can be regarded as a new determinant of prostate inflammation and BPH progression.
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