► Effect of laser peening without coating (LPwC) on fatigue life of Ti alloys was studied. ► High cycle fatigue life was prolonged in Ti–2.5Cu and LCB and deteriorated in Ti-54M. ► Results were ...mainly interpreted by residual stresses and surface morphology. ► Residual stress is thermally more stable after LPwC than that after shot peeing. ► Surface vaporization due to LPwC results in very rough surface.
Laser shock peening can potentially enhance fatigue life of titanium components by inducing compressive residual stresses in surface layers much deeper than caused by traditional shot peening (SP). In the present study, the high cycle fatigue (HCF) performance of α Ti-alloy Ti–2.5Cu, (α+β) Ti-alloy TIMETAL 54M and the metastable β Ti-alloy TIMETAL LCB was investigated after laser shock peening without coating (LPwC). The fatigue results were interpreted by examining the changes of surface morphology, microhardness and residual stress generated in the surface layer. Furthermore, thermal stability of residual stresses in aged Ti–2.5Cu, as an example, was evaluated after annealing LPwC-treated material at various elevated temperatures and exposure times by applying a Zener–Wert–Avrami approach. The depth profiles of residual stresses were obtained by means of synchrotron X-ray diffraction or by incremental hole drilling method. Results revealed that the HCF performance of Ti–2.5Cu and TIMETAL LCB was markedly improved after LPwC, while it was deteriorated in TIMETAL 54M. Compared to LPwC, better 107 fatigue strength of Ti–2.5Cu was obtained after ball-burnishing (BB). Moreover, LPwC-induced residual stresses are thermally more stable than shot peening-induced ones.
► Effect of laser peening without coating on friction stir welded A6061-T6 joint. ► Compressive residual stress was imparted on the joint. ► Hardness on the stir zone was recovered in some degree. ► ...Fatigue strength was improved from 90 to 120MPa at 107 cycles. ► This strength was higher than that of unwelded base material.
The authors have applied laser peening without coating (LPwC) to fatigue specimens cut out from friction stir welded (FSWed) A6061-T6 aluminum alloy plates with a thickness of 3mm. Both crown and root sides of the specimens were peened by laser pulses with an energy of 60mJ and a peak power density of 2GW/cm2 from a frequency-doubled Nd:YAG laser. The effects on the fatigue properties were studied through plane bending fatigue tests with a stress ratio of R=−1. The results showed that the fatigue strength of unwelded specimens (base material; BM) was 110MPa at 107 cycles and LPwC enhanced the strength by 60MPa in spite of increase in surface roughness due to the direct irradiation of the laser pulses to the bare surface of the specimens. Meanwhile the fatigue strength of FSWed specimens was 90MPa and LPwC enhanced it by 30MPa to 120MPa. This increment is a half compared to that in the BM, however the fatigue strength of the FSWed specimens after LPwC was higher than that of the BM. The surface roughness, hardness and residual stress were assessed and characterized as well.
Treatments that stimulate neuronal excitability enhance motor performance after stroke. cAMP-response-element binding protein (CREB) is a transcription factor that plays a key role in neuronal ...excitability. Increasing the levels of CREB with a viral vector in a small pool of motor neurons enhances motor recovery after stroke, while blocking CREB signaling prevents stroke recovery. Silencing CREB-transfected neurons in the peri-infarct region with the hM4Di-DREADD blocks motor recovery. Reversing this inhibition allows recovery to continue, demonstrating that by manipulating the activity of CREB-transfected neurons it is possible to turn off and on stroke recovery. CREB transfection enhances remapping of injured somatosensory and motor circuits, and induces the formation of new connections within these circuits. CREB is a central molecular node in the circuit responses after stroke that lead to recovery from motor deficits.
Colorectal cancer (CRC) is rapidly increasing in Asia, but screening guidelines are lacking. Through reviewing the literature and regional data, and using the modified Delphi process, the Asia ...Pacific Working Group on Colorectal Cancer and international experts launch consensus recommendations aiming to improve the awareness of healthcare providers of the changing epidemiology and screening tests available. The incidence, anatomical distribution and mortality of CRC among Asian populations are not different compared with Western countries. There is a trend of proximal migration of colonic polyps. Flat or depressed lesions are not uncommon. Screening for CRC should be started at the age of 50 years. Male gender, smoking, obesity and family history are risk factors for colorectal neoplasia. Faecal occult blood test (FOBT, guaiac-based and immunochemical tests), flexible sigmoidoscopy and colonoscopy are recommended for CRC screening. Double-contrast barium enema and CT colonography are not preferred. In resource-limited countries, FOBT is the first choice for CRC screening. Polyps 5-9 mm in diameter should be removed endoscopically and, following a negative colonoscopy, a repeat examination should be performed in 10 years. Screening for CRC should be a national health priority in most Asian countries. Studies on barriers to CRC screening, education for the public and engagement of primary care physicians should be undertaken. There is no consensus on whether nurses should be trained to perform endoscopic procedures for screening of colorectal neoplasia.
Summary
Thymic stromal lymphopoietin (TSLP) is known for its capacity to induce CD11c+ myeloid dendritic cells to promote T helper type 2 (Th2)‐skewed inflammatory responses. Although increased ...expression of TSLP was reported in the lesional skin of limited numbers of patients with atopic dermatitis (AD), the relationships between the degree of TSLP expression in the skin and the severity of AD, epidermal barrier function and eruption type remain to be elucidated. The aim of this study was to examine the relationships between the degree of TSLP expression in the skin and the severity of AD, eruption type and epidermal barrier function using a non‐invasive method in a sizeable group of the patients. Stratum corneum tissue was obtained from AD patients by tape stripping, and the stratum corneum TSLP (scTSLP) expression level was evaluated using a TSLP‐specific antibody followed by image analysis. The correlations between the scTSLP intensity and the severity scoring of AD (SCORAD) index and epidermal barrier function, such as stratum corneum hydration and transepidermal water loss (TEWL), were analysed. The changes in the scTSLP level induced by the application of moisturizer were also examined. The scTSLP expression level was increased in AD patients compared with healthy subjects and was correlated with SCORAD, especially with the dry skin score, and stratum corneum hydration. Moisturizer application resulted in reduced scTSLP levels. The scTSLP level can be used as a biomarker of AD severity and particularly epidermal barrier status.
In order to improve the performance of a filter press type electro-dialysis (E.D.) system, 5 types of hollow cubic assembled porous spacer fabricated by a 3D printer were applied instead of the ...conventional mesh spacers. The effects of structure of porous spacers on the E.D. system performance were experimentally investigated in terms of limiting current density, stack voltage and pressure drop. It was found that the porous spacer with vertical staggered arrangement normal to membrane surface and with smaller interfacial surface area between spacer and membranes contributes a higher limiting current density, which is about 2.5–3.0 times higher than that of E.D. system without spacer. Moreover, this spacer filled in E.D. system results in a relative lower electrical resistance and a smaller pumping power compare to other spacers. Since the vertical staggered structure is able to mix the flow (i.e. mechanical dispersion), supplies ions in the flow towards membranes, and suppresses concentration polarization, so that increases the LCD at expense of slightly increase in electrical resistance. Moreover, dimensionless mechanical dispersion coefficient towards membranes was estimated by fitting the experimental data with the analytical solution proposed in previous paper. Finally, a suggestion for making a good porous spacer has been proposed.
•Improve the performance of E.D. system using new type porous spacers•Hollow cubic assembled porous spacers fabricated by 3D printer were applied instead of conventional mesh spacers.•The fluid mixing towards membranes is significant for enhance E.D. system performance in terms of LCD and energy consumption.•A suggestion of designing structure of porous spacers was proposed.
A new type of interrogator for distributed fiber Bragg grating (FBG) sensors that employs an arrayed waveguide grating (AWG) is proposed and its operating features are in detail investigated both ...theoretically and experimentally. The remedy for achieving the linear characteristics of wavelength detection as well as for insuring the reliable and environmentally stable operation of interrogation is proposed and its usefulness is demonstrated in good agreement with the experimental results. The developed interrogator consists of a fully passive, small, all-solid, rugged optical IC and can detect wavelengths of a great number of FBG sensors with high precision better than 0.5 pm and high speed.
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