Probing the assembly mechanism, orientation, shape, and structure function relationship of hybrid supramolecular materials is an outstanding challenge. In this regard, we have presented a novel ...method based on fluorescence spectroscopic Mueller matrix measurements and inverse analysis which can probe and quantify exclusive information on the molecular organization and orientation via a set of newly defined fluorescence anisotropy parameters, namely, fluorescence diattenuation and polarizance. A new dipeptide motif Boc-Xaa-Met-OMe (Xaa = Val/Leu) containing leucine, valine, and methionine forms a kink like structure and self-associates to form a twisted sheet like structure by multiple intermolecular N–H···O hydrogen bonds and finally grown to form supramolecular nanotubes having a diameter ca. 10 Å. Thus, the methionine sulfurs of peptide molecules are arranged helically along the tubes, work as a hot spot, and help to stabilize the electron deficient paint TB-NDI around the tube. The fluorescence Mueller matrix polarimetry and inverse analysis offers insight on the molecular organization and orientation of the achiral fluorescent dye molecules around the supramolecular nanotube from the chiral dipeptide. This method is promising for characterization of complex hybrid materials.
The detrimental effects of submergence on physiological performances of some rice varieties with special references to carbohydrate metabolisms and their allied enzymes during post-flowering stages ...have been documented and clarified in the present investigation. It was found that photosynthetic rate and concomitant translocation of sugars into the panicles were both related to the yield. The detrimental effects of the complete submergence were recorded in generation of sucrose, starch, sucrose phosphate synthase and phosphorylase activity in the developing panicles of the plants as compared to those under normal or control （i.e. non-submerged） condition. The accumulation of starch was significantly lower in plants under submergence and that was correlated with ADP-glucose pyrophosphorylase activity. Photosynthetic rate was most affected under submergence in varying days of post-flowering and was also related to the down regulation of Ribulose bisphosphate carboxylase activity. However, under normal or control condition, there recorded a steady maintenance of photosynthetic rate at the post-flowering stages and significantly higher values of Ribulose bisphosphate carboxylase activity. Still, photosynthetic rate of the plants under both control and submerged conditions had hardly any significant correlation with sugar accumulation and other enzymes of carbohydrate metabolism like invertase with grain yield. Finally, plants under submergence suffered significant loss of yield by poor grain filling which was related to impeded carbohydrate metabolism in the tissues. It is evident that loss of yield under submergence is attributed both by lower sink size or sink capacity （number of panicles, in this case） as well as subdued carbohydrate metabolism in plants and its subsequent partitioning into the grains.
Spatial variation of refractive index (RI) in connective tissues exhibits multifractality, which encodes useful morphological and ultrastructural information about the disease. We present a spectral ...Mueller matrix (MM)-based approach in combination with multifractal detrended fluctuation analysis (MFDFA) to exclusively pick out the signature of the underlying connective tissue multifractality through the superficial epithelium layer. The method is based on inverse analysis on selected spectral scattering MM elements encoding the birefringence information on the anisotropic connective tissue. The light scattering spectra corresponding to the birefringence carrying MM elements are then subjected to the Born approximation-based Fourier domain preprocessing to extract ultrastructural RI fluctuations of anisotropic tissue. The extracted RI fluctuations are subsequently analyzed via MFDFA to yield the multifractal tissue parameters. The approach was experimentally validated on a simple tissue model comprising of TiO2 as scatterers of the superficial isotropic layer and rat tail collagen as an underlying anisotropic layer. Finally, the method enabled probing of precancer-related subtle alterations in underlying connective tissue ultrastructural multifractality from intact tissues.
There are extensive reports on bathochromic emissive material associated with non‐covalent interaction but the reports on emissive material with covalent crosslinked approach is limited. Therefore, ...we highlight unique method for synthesis of crosslinked polymeric materials formed via thermal Click reaction where the static aggregate of naphthalene (Np) in Polym‐Np or pyrene (Py) in Polym‐Py showed energy tunable emission. Initially, the crosslinked polymeric materials were well‐characterized using spectroscopic and analytical methods like NMR, ATR‐FTIR, rheometer, TGA and optical analysis. The energy tunability to fluorescence emission with polynuclear aromatic hydrocarbons (PAHs) ‐ naphthalene and pyrene was observed. The quantum efficiency for the respective crosslinked polymers—Polym‐Np and Polym‐Py was found to be 2.54% and 8.72%. Moreover, the Full polarization fluorescence Mueller matrix (FLMM) spectroscopy was invoked to extract and quantify the molecular orientation of the ground and excited state of the crosslinked polymers—Polym‐Np and Polym‐Py. The polarization parameters (Fluorescence Diattenuation and Polarizance) based on fluorescence polarization showed that the PAHs within the crosslinked polymers found to be well organized in the excited state with respect to the ground state. Such materials have potential to application such as photocatalyst, chemosensor, etc.
•Automated detection of brain injury in the neonate is critically needed but lacking.•Three approaches were tested: symmetry, watershed and hierarchical splitting.•SIRG performed the best for lesion ...volume.•HRS was the most robust (smallest standard deviations).•MWS lagged in performance on all measures.
We compared the efficacy of three automated brain injury detection methods, namely symmetry-integrated region growing (SIRG), hierarchical region splitting (HRS) and modified watershed segmentation (MWS) in human and animal magnetic resonance imaging (MRI) datasets for the detection of hypoxic ischemic injuries (HIIs). Diffusion weighted imaging (DWI, 1.5T) data from neonatal arterial ischemic stroke (AIS) patients, as well as T2-weighted imaging (T2WI, 11.7T, 4.7T) at seven different time-points (1, 4, 7, 10, 17, 24 and 31days post HII) in rat-pup model of hypoxic ischemic injury were used to assess the temporal efficacy of our computational approaches. Sensitivity, specificity, and similarity were used as performance metrics based on manual (‘gold standard’) injury detection to quantify comparisons. When compared to the manual gold standard, automated injury location results from SIRG performed the best in 62% of the data, while 29% for HRS and 9% for MWS. Injury severity detection revealed that SIRG performed the best in 67% cases while 33% for HRS. Prior information is required by HRS and MWS, but not by SIRG. However, SIRG is sensitive to parameter-tuning, while HRS and MWS are not. Among these methods, SIRG performs the best in detecting lesion volumes; HRS is the most robust, while MWS lags behind in both respects.
On 2019 July 2 a total solar eclipse-visible across parts of the Southern Pacific Ocean, Chile, and Argentina-enabled observations of the Sun's corona. The structure and emission characteristics of ...the corona are determined by underlying magnetic fields, which also govern coronal heating and solar eruptive events. However, coronal magnetic field measurements remain an outstanding challenge. Coronal magnetic field models serve an important purpose in this context. Earlier work has demonstrated that the large-scale coronal structure is governed by surface flux evolution and memory buildup, which allows for its prediction on solar rotational timescales. Utilizing this idea and based upon a 51 day forward run of a predictive solar surface flux transport model and a potential field source surface model, we predict the coronal structure of the 2019 July 2 solar eclipse. We also forward model the polarization characteristics of the coronal emission. Our prediction of two large-scale streamer structures and their locations on the east and west limbs of the Sun match eclipse observations reasonably well. We demonstrate that the Sun's polar fields strongly influence the modeled corona, concluding that accurate polar field observations are critical. This study is relevant for coronal magnetometry initiatives envisaged with the Daniel K. Inouye Solar Telescope, Coronal Multichannel Polarimeter and upcoming space-based instruments such as Solar Orbiter, Solar Ultraviolet Imaging Telescope and the Variable Emission Line Coronagraph on board the Indian Space Research Organisation's Aditya-L1 space mission.
Information on the polarization properties of scattered light from plasmonic systems are of paramount importance due to fundamental interest and potential applications. However, such studies are ...severely compromised due to the experimental difficulties in recording full polarization response of plasmonic nanostructures. Here, we report on a novel Mueller matrix spectroscopic system capable of acquiring complete polarization information from single isolated plasmonic nanoparticle/nanostructure. The outstanding issues pertaining to reliable measurements of full 4 × 4 spectroscopic scattering Mueller matrices from single nanoparticle/nanostructures are overcome by integrating an efficient Mueller matrix measurement scheme and a robust eigenvalue calibration method with a dark-field microscopic spectroscopy arrangement. Feasibility of quantitative Mueller matrix polarimetry and its potential utility is illustrated on a simple plasmonic system, that of gold nanorods. The demonstrated ability to record full polarization information over a broad wavelength range and to quantify the intrinsic plasmon polarimetry characteristics via Mueller matrix inverse analysis should lead to a novel route towards quantitative understanding, analysis/interpretation of a number of intricate plasmonic effects and may also prove useful towards development of polarization-controlled novel sensing schemes.
A novel spectroscopic Mueller matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric measurements from biological tissues. The 4 × 4 Mueller matrix ...measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller matrix measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.
Arterial blood pressure (ABP) is a vital hemodynamic signal to be monitored in general population- especially in critically ill patients. Pulse arrival time (PAT) has been widely used for the ...noninvasive measurement of systolic blood pressure (SBP) and diastolic blood pressure (DBP) and has shown excellent results for a healthy person as compared to the existing gold standard methods. In this study, we have used correlation analysis to study the feasibility of using PAT and heart rate (HR) for noninvasive BP (SBP and DBP) measurement for critically ill subjects. Physiological signals used for this study were collected from the MIMIC-II database of Physionet. Initially, we conducted a correlation analysis and then tried to estimate BP using linear regression. We found that the BP correlation with HR is more as compared with PAT. However, these correlations are not consistent. We have also found that PAT and HR can track the BP change as long as the correlation coefficient lies between ±0.7 and ±1. When the correlation falls below, this noninvasive BP estimation using PAT and HR needs to be revisited and improved for clinical applicability.
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