100 research outputs found
The magnetic phase diagram of underdoped YBa2Cu3Oy inferred from torque magnetization and thermal conductivity
Strong evidence for charge-density correlation in the underdoped phase of the
cuprate YBa2Cu3Oy was obtained by nuclear magnetic resonance (NMR) and resonant
x-ray scatter- ing. The fluctuations were found to be enhanced in strong
magnetic fields. Recently, 3D (three dimensional) charge-density wave (CDW)
formation with long-range order (LRO) was observed by x-ray diffraction in H
>15 T. To elucidate how the CDW transition impacts the pair condensate, we have
used torque magnetization to 45 T and thermal conductivity to
construct the magnetic phase diagram in untwinned crystals with hole density p
= 0.11. We show that the 3D CDW transitions appear as sharp features in the
susceptibility and at the fields HK and Hp, which define phase
boundaries in agreement with spectroscopic techniques. From measurements of the
melting field Hm(T) of the vortex solid, we obtain evidence for two vortex
solid states below 8 K. At 0.5 K, the pair condensate appears to adjust to the
3D CDW by a sharp transition at 24 T between two vortex solids with very
different shear moduli. At even higher H (42 T) the second vortex solid melts
to a vortex liquid which survives to fields well above 45 T. de Haas-van Alphen
oscillations appear at fields 24-28 T, below the lower bound for the upper
critical field Hc2.Comment: 7 pages, 8 figures; New version of previous posting, reporting torque
measurements to 45 Tesla and final magnetic phase diagra
Inhibition of Renin-Angiotensin System Reverses Endothelial Dysfunction and Oxidative Stress in Estrogen Deficient Rats
BACKGROUND: Estrogen deficiency increases the cardiovascular risks in postmenopausal women. Inhibition of the renin-angiotensin system (RAS) and associated oxidative stress confers a cardiovascular protection, but the role of RAS in estrogen deficiency-related vascular dysfunction is unclear. The present study investigates whether the up-regulation of RAS and associated oxidative stress contributes to the development of endothelial dysfunction during estrogen deficiency in ovariectomized (OVX) rats. METHODOLOGY/PRINCIPAL FINDINGS: Adult female rats were ovariectomized with and without chronic treatment with valsartan and enalapril. Isometric force measurement was performed in isolated aortae. The expression of RAS components was determined by immunohistochemistry and Western blotting method while ROS accumulation in the vascular wall was evaluated by dihydroethidium fluorescence. Ovariectomy increased the expression of angiotensin-converting enzyme (ACE), angiotensin II type 1 receptor (AT(1)R), NAD(P)H oxidase, and nitrotyrosine in the rat aorta. An over-production of angiotensin II and ROS was accompanied by decreased phosphorylation of eNOS at Ser(1177) in OVX rat aortae. These pathophysiological changes were closely coupled with increased oxidative stress and decreased nitric oxide bioavailability, culminating in markedly impaired endothelium-dependent relaxations. Furthermore, endothelial dysfunction and increased oxidative stress in aortae of OVX rats were inhibited or reversed by chronic RAS inhibition with enalapril or valsartan. CONCLUSIONS/SIGNIFICANCE: The novel findings highlight a significant therapeutic benefit of RAS blockade in the treatment of endothelial dysfunction-related vascular complications in postmenopausal states
Locally Administrated Perindopril Improves Healing in an Ovariectomized Rat Tibial Osteotomy Model
Angiotensin-converting enzyme inhibitors are widely prescribed to regulate blood pressure. High doses of orally administered perindopril have previously been shown to improve fracture healing in a mouse femur fracture model. In this study, perindopril was administered directly to the fracture area with the goal of stimulating fracture repair. Three months after being ovariectomized (OVX), tibial fractures were produced in Sprague–Dawley rats and subsequently stabilized with intramedullary wires. Perindopril (0.4 mg/kg/day) was injected locally at the fractured site for a treatment period of 7 days. Vehicle reagent was used as a control. Callus quality was evaluated at 2 and 4 weeks post-fracture. Compared with the vehicle group, perindopril treatment significantly increased bone formation, increased biomechanical strength, and improved microstructural parameters of the callus. Newly woven bone was arranged more tightly and regularly at 4 weeks post-fracture. The ultimate load increased by 66.1 and 76.9% (p<0.01), and the bone volume over total volume (BV/TV) increased by 29.9% and 24.3% (p<0.01) at 2 and 4 weeks post-fracture, respectively. These findings suggest that local treatment with perindopril could promote fracture healing in ovariectomized rats
Advances in heterometallic ring-opening (co)polymerisation catalysis
Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts. This review describes advances in heterometallic RO(CO)P catalyst design, highlighting the overarching structure-activity trends and reactivity patterns to inform future catalyst design
CARE CAMPUS. A EUROPEAN CONSORTIUM MODEL TO SUPPORT FORMAL AND INFORMAL CAREGIVING TRAINING
Today’s health and social care systems are facing a challenge in how to effectively address caregiving for ageing populations facing cognitive disorders and frailty. Scholars and policy makers are now identifying a rise of “hidden form of care”, e.g. informal caregiving, as a phenomenon in support for ageing populations. Across Europe for instance, the rise in the older old adult population has led to a rapid expansion of the number of carers, both professional (formal) and informal. The latter, representing mostly family members caring for their loved ones, truly represents a “hidden form of care”. This can be a problem if formal and informal caregivers are not fully integrated into the healthcare continuum or are not given a systematic support to carry out caregiving in a relevant and safe way. There is currently no comprehensive European-wide legal framework and support mechanisms, in terms of training and education for this group. CARE Campus, an EIT Health programme within the Educational Campus Pillar, is a new model of collaboration between academic institutions, the private sector, and the public sector whose main aim is to support the development of a comprehensive training for formal and informal caregivers in Europe. The initial phase of the development encompasses nine (09) online training modules with a quality control process to ensure that the curriculum is evidence-based, compliant with the national and local regulations, and addresses the needs of caregivers across Europe. The objective is to support formal, informal, and family caregivers and reduce the burden on health care systems, whilst improving the quality of care for older adults
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