Global impact of COVID-19 on stroke care

Background: The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide. Aims: We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy, stroke, and intracranial hemorrhage hospitalizations over a three-month period at the height of the pandemic (1 March–31 May 2020) compared with two control three-month periods (immediately preceding and one year prior). Methods: Retrospective, observational, international study, across 6 continents, 40 countries, and 187 comprehensive stroke centers. The diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases at participating centers. Results: The hospitalization volumes for any stroke, intracranial hemorrhage, and mechanical thrombectomy were 26,699, 4002, and 5191 in the three months immediately before versus 21,576, 3540, and 4533 during the first three pandemic months, representing declines of 19.2% (95%CI, −19.7 to −18.7), 11.5% (95%CI, −12.6 to −10.6), and 12.7% (95%CI, −13.6 to −11.8), respectively. The decreases were noted across centers with high, mid, and low COVID-19 hospitalization burden, and also across high, mid, and low volume stroke/mechanical thrombectomy centers. High-volume COVID-19 centers (−20.5%) had greater declines in mechanical thrombectomy volumes than mid- (−10.1%) and low-volume (−8.7%) centers (p < 0.0001). There was a 1.5% stroke rate across 54,366 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.9% (784/20,250) of all stroke admissions. Conclusion: The COVID-19 pandemic was associated with a global decline in the volume of overall stroke hospitalizations, mechanical thrombectomy procedures, and intracranial hemorrhage admission volumes. Despite geographic variations, these volume reductions were observed regardless of COVID-19 hospitalization burden and pre-pandemic stroke/mechanical thrombectomy volumes

Evidence for the presence of remnant strain in grey-tracked KTiOPO4KTiOPO_4

Grey tracks produced in $KTiOPO_4$ (KTP) by applying a dc electric field have been studied through optical absorption, Raman scattering, and synchrotron x-ray topography. A study of the optical absorption and Raman scattering from the grey-tracked region suggests that their formation is accompanied by changes in the electronic levels of $Ti^{4+}$. There is no evidence for a major structural change or disorder in the grey-tracked region. However, the x-ray topographs do indicate the presence of a remnant strain in the lattice, which might contribute to the observed changes in the Raman intensities

Evidence for the presence of remnant strain in grey‐tracked KTiOPO4

Grey tracks produced in KTiOPO4 (KTP) by applying a dc electric field have been studied through optical absorption, Raman scattering, and synchrotron x‐ray topography. A study of the optical absorption and Raman scattering from the grey‐tracked region suggests that their formation is accompanied by changes in the electronic levels of Ti4+. There is no evidence for a major structural change or disorder in the grey‐tracked region. However, the x‐ray topographs do indicate the presence of a remnant strain in the lattice, which might contribute to the observed changes in the Raman intensities

Aqueous sol-derived ferroelectric thin films of PbTiO3 directly on Si(100) substrate

Ferroelectric thin films of PbTiO3 are prepared directly on Si(100) substrate for the first time by spin coating an aqueous sol of lead and titanium hydroxy complex and post annealing at various temperatures. The X-ray diffraction patterns show that the films are polycrystalline in nature. Scanning electron microscopy reveals that the films 0.3 mu m in thickness are essentially crack-free. Since there is no organic content in the precursor solution, post deposition shrinkage is reduced. This helps to decrease the possibility of film cracking. The ferroelectric properties of the films are comparable to those obtained by the complex alkoxide route and other expensive techniques. Copyright (C) 1997

Synthesis and Sintering Of PZT Ceramics

Lead zirconate powder, with Zr/Ti ratio of 50/50 was prepared by polymeric precursor method and doped with 3, 5 and 7 mol% of Sr+2 Or Ba+2, as well as by 0.2 to 5 mol% of Nb+5. The powder was calcined at 750 degrees C by 4 hours and milled during 1.5 h in isopropilic alcohol. Powders were characterized by surface area measurements (BET method), by infrared spectroscopy and by X-ray diffraction to characterize the crystal structure. Isostatically pressed samples were sintered in a dilatometer furnace by using a constant heating rate of 10 degrees C/min from ambient to 1200 degrees C. Synthetic air and air with water vapor were used as atmospheres. Both Sr+2 and Ba+2 substitute Pb+2 and favor the formation of rhombohedral phase. Otherwise, Nb+5 substitute preferentially Zr+4 favoring tetragonal phase. The concentration of dopants and the atmosphere influence the densification and the microstructure of the PZT, which alters the dielectric and piezoelectric properties of the ceramics.UNESP, Inst Chem, BR-14801970 Araraquara, SP, BrazilUNESP, Inst Chem, BR-14801970 Araraquara, SP, Brazi

The current state of retinopathy of prematurity in India, Kenya, Mexico, Nigeria, Philippines, Romania, Thailand, and Venezuela

Retinopathy of prematurity (ROP) is one of the leading causes of preventable blindness in children worldwide. Middle-income nations are currently experiencing epidemic levels of ROP, because greater access to neonatal intensive care units has improved survival rates of premature infants, but without sophisticated oxygen regulation. The epidemiology, screening infrastructure, treatment options, and challenges that these countries face are often tied to unique local socioeconomic, cultural, geopolitical, and medical factors. We present an overview and narratives of the current state of ROP in eight countries that are or soon will be experiencing ROP epidemics—India, Kenya, Mexico, Nigeria, Phillipines, Romania, Thailand, and Venezuela—with a view to fostering both an understanding of the differences in the ROP landscape in various settings and an interest in the further development of ROP screening and treatment services tailored to local requirements.</jats:p