Cardiac MRI and 2Dimensional speckle Tracking Echocardiography (2D STE) are the most sought-after methods to evaluate LV twist mechanics. LV rotational deformation resembles the wringing of a towel, and this deformation is referred as LV twist (LVT), and the subsequent recoil in diastole is known as LV untwist (LVUT). 2D/3D/4D twist mechanics assessment by STE is inherently associated with limitations. Recently introduced 4D XStrain STE has been used for evaluation of strain parameters because of better appraisal of contractile properties of LV, to analyse complex multi-dimensional LV rotational mechanics. This novel technology is a reliable, affordable, and simple tool for quantification of regional myocardial functions, particularly LV strain and rotation parameters. To evaluate and establish the normal values of LV rotation and twist by 4D XStrain STE in healthy Indian adults during the Covid-19 pandemic was the aim of the current study. 46 subjects were enrolled (34 males & 12 females). LA size, LV mass, CO, LVEDV and mitral E/A ratio were significantly greater in males (p<0.01) even though EF was higher in females (p<0.01). GLS, GCS, and GRS were increased in males (p<0.01). Peak basal rotation, peak twist, peak twist rate, and peak untwist rate were also greater in males (p<0.01), nonetheless, peak apical rotation and papillary muscle rotational velocity were greater in females (p<0.01). However, MV rotational velocity was increased in males (p<0.01). This is the first research publication of normal values of LV rotation and twists in healthy Indian adults by 4D XStrain STE.
Global longitudinal strain (GLS) is a sensitive measure of LV dysfunction and is better than EF at predicting CVD events and deaths. Recently 3D/4D/4D X strain speckle tracking echocardiography (STE) is used to analyse complex LV mechanics. Interestingly, HFpEF is related to both GLS and increased Aortic stiffness. TDI of ascending Aorta is an effective technique to assess Aortic stiffness. The aim of the present study is to establish normal values of TDI of AA by 2DE and 4D X-strain volumetric and strain parameters of LV of healthy adults. 102 subjects were enrolled, 72 assessed by 2DE-GROUP-A, and 30 were analysed by 4D X-strain echocardiography-GROUP-B. Important TDI parameters of Aortic stiffness were 3.90 ±3.79& 5.23 ± 10.55, (p = NS), in males & females respectively and Aortic strain were 10.55 ± 7.67% and 9.49 ± 5.56%, (p = NS), in males & females respectively. Volumetric data of EF were 64 ± 7.0 % & 65 ± 6.0 %, (p = NS), in males & females respectively and CO were 5.6 ± 1.5 l/min & 4.91±1.53l/min, (p = NS), in males & females respectively. Moreover, 4D X-strain STE indices of GLS being -17.29 ± 2.71 & -19.00 ± 3.51, (p = NS), in males & females, respectively GCS being -15.46 ± 7.1 & -14.12 ± 6.15, (p =NS), in males & females respectively and GRS being -24.53 ± 9.8 & -21.93 ± -8.81, (p= NS), in males & females respectively. No previous data is available, making the research a singular experience.
Dilute-nitride GaAsNx epilayers were grown on GaAs (001) substrates at temperatures of ∼450 °C using a radio-frequency plasma-assisted molecular/chemical beam exitaxy system. The concentration of nitrogen incorporated into the films was varied in the range between 0.01 and 0.04. High-resolution electron microscopy was used to determine the cross-sectional morphology of the epilayers, and Z-contrast imaging showed that the incorporated nitrogen was primarily interstitial. {110}-oriented microcracks, which resulted in strain relaxation, were observed in the sample with the highest N concentration ([N] ∼ 3.7%). Additionally, Z-contrast imaging indicated the formation of a thin, high-N quantum-well-like layer associated with initial ignition of the N-plasma. Significant N contamination of the GaAs barrier layers was observed in all samples, and could severely affect the carrier extraction and transport properties in future targeted devices. Dilute-nitride quantum-well-based photovoltaic solar cells were fabricated having a band-gap energy of 1.19 eV, which was attributed to the dilute-nitride layer.
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