A line-scanning semi-confocal multi-photon fluorescence microscope with a simultaneous broadband spectral acquisition and its application to the study of the thylakoid membrane of a cyanobacterium Anabaena PCC7120

We describe the construction and characterization of a laser‐line‐scanning microscope capable of detection of broad fluorescence spectra with a resolution of 1 nm. A near‐infrared femtosecond pulse train at 800 nm was illuminated on a line (one lateral axis, denoted as X axis) in a specimen by a resonant scanning mirror oscillating at 7.9 kHz, and total multi‐photon–induced fluorescence from the linear region was focused on the slit of an imaging polychromator. An electron‐multiplying CCD camera was used to resolve fluorescence of different colours at different horizontal pixels and fluorescence of different spatial positions in a specimen at different vertical pixels. Scanning on the other two axes (Y and Z) was achieved by a closed‐loop controlled sample scanning stage and a piezo‐driven objective actuator. The full widths at half maximum of the point‐spread function of the system were estimated to be 0.39–0.40, 0.33 and 0.56–0.59 μm for the X (lateral axis along the line‐scan), Y (the other lateral axis) and Z axes (the axial direction), respectively, at fluorescence wavelengths between 644 and 690 nm. A biological application of this microscope was demonstrated in a study of the sub‐cellular fluorescence spectra of thylakoid membranes in a cyanobacterium, Anabaena PCC7120. It was found that the fluorescence intensity ratio between chlorophyll molecules mainly of photosystem II and phycobilin molecules of phycobilisome (chlorophyll/phycobilin), in the thylakoid membranes, became lower as one probed deeper inside the cells. This was attributable not to position dependence of re‐absorption or scattering effects, but to an intrinsic change in the local physiological state of the thylakoid membrane, with the help of a transmission spectral measurement of sub‐cellular domains. The efficiency of the new line‐scanning spectromicroscope was estimated in comparison with our own point‐by‐point scanning spectromicroscope. Under typical conditions of observing cyanobacterial cells, the total exposure time became shorter by about 50 times for a constant excitation density. The improvement factor was proportional to the length of the line‐scanned region, as expected.     

Analysis of stiffness and flexural strength of a reinforced concrete beam using an invented reinforcement system

In this study, we conducted experimental tests on two specimens of reinforced concrete beams using a three-point bending test to optimize the flexure and stiffness designs. The first specimen is a reinforced concrete beam with an ordinary reinforcement, and the second specimen has an invented reinforcement system that consists of an ordinary reinforcement in addition to three additional bracings using steel bars and steel plates. The results of the flexure test were collected and analyzed, and the flexural strength, the rate of damage during bending, and the stiffness were determined. Finite element modeling was applied for both specimens using the LS-DYNA program, and the simulation results of the flexure test for the same outputs were determined. The results of the experimental tests showed that the flexural strength of the invented reinforcement system was significantly enhanced by 15.5% compared to the ordinary system. Moreover, the flexural cracks decreased to a significant extent, manifesting extremely small and narrow cracks in the flexure spread along the bottom face of the concrete. In addition, the maximum deflection for the invented reinforced concrete beam decreased to 1/3 compared to that of an ordinary reinforced concrete beam. The results were verified through numerical simulations, which demonstrated excellent similarities between the flexural failure and the stiffness of the beam. The invented reinforcement system exhibited a high capability in boosting the flexure design and stiffness.     

Expression analysis of <i>OsSERK</i>, <i>OsLEC1</i> and <i>OsWOX4</i> genes in rice (<i>Oryza</i> sativa L.) callus during somatic embryo development

Somatic embryogenesis is an asexual reproduction process that occurs in many plant species, including rice. This process contains several totipotency markers such as Somatic Embryogenesis Receptor-like Kinase (SERK), Leafy Cotyledon1 (LEC1) and WUSCHEL-Related Homeobox4 (WOX4) and also a helpful model for embryo development and clones and transformations. Here, we report the gene expression during somatic embryo development correlates with regeneration frequency in 14 Javanica rice (pigmented and non-pigmented) using modifified N6 media supplemented with Kinetin (2.0 mg/L) and NAA (1.0 mg/L). Although there have been advances in understanding the genetic basis of somatic embryogenesis in other varieties, rice is still unexplored, especially during somatic embryo development. Moreover, for the formation of callus induction from immature embryos, 2,4-D (2.0 mg/L, 3.0 mg/L) was used. This study analysed the gene expression of OsSERK, OsWOX4 and OsLEC1 genes through RT-PCR analysis. Higher expression of the OsLEC1 gene indicates that their function may correlate in the in vitro with the high response of rice after transfer to regeneration media. This study found that rice varieties of pigmented rice (MS Pendek and Gogoniti II) and non-pigmented rice (Pandan Ungu) showed high regeneration frequency, showing higher OsLEC1 expression than other varieties because OsLEC1 promotes the maturation of somatic embryos in plant regeneration on day 14. However, the contrast with Genjah nganjuk may be effective because of other regulatory genes. RT-PCR analysis showed OsSERK had less expression level than OsLEC1 and OsWOX4 in the varieties, which correlate with the percentage of plant regeneration, but not for Gogoniti II. In conclusion, the higher percentage of plant regeneration correlates with the higher expression level of OsLEC1 at day 14 of media regeneration of rice.     

Delineating the role of phytocompounds against anti-bacterial drug resistance–An update

Antibacterial resistance developed by bacteria due to the unlimited use of antibiotics has posed a challenge forhuman civilization. This kind of problem is not limited to India only, but it is a global concern. Nowadays, manytreatments and medicines for bacterial diseases have been developed. However, they possess some drawbacks.Therefore, the alternative medicine has been used to target the drug resistant mechanisms and such medicines haveless side effects which is becoming necessary. Natural products have traditionally or historically been of importancefor the development of antibacterial agents and are also known to overcome bacterial drug resistance by directlytargeting the drug resistance mechanisms in bacteria. In recent years, researchers have also focused on new drugdiscovery from plant-based research. They have looked on various phytocompounds as antibacterial agents. In thecurrent review, we report various classes of secondary metabolites such as phenolic compounds, flavonoids, alkaloids,saponins, terpenes, quinones, and some essential oils that have been used as an antibacterial agent. In addition, wealso discuss several mechanisms behind bacterial multi-drug resistance that are used during bacterial pathogenesis.     

Application of an advanced maximum likelihood estimation restoration method for enhanced‐resolution and contrast in second‐harmonic generation microscopy

Second‐harmonic generation (SHG) microscopy has gained popularity because of its ability to perform submicron, label‐free imaging of noncentrosymmetric biological structures, such as fibrillar collagen in the extracellular matrix environment of various organs with high contrast and specificity. Because SHG is a two‐photon coherent scattering process, it is difficult to define a point spread function (PSF) for this modality. Hence, compared to incoherent two‐photon processes like two‐photon fluorescence, it is challenging to apply the various PSF‐engineering methods to improve the spatial resolution to be close to the diffraction limit. Using a synthetic PSF and application of an advanced maximum likelihood estimation (AdvMLE) deconvolution algorithm, we demonstrate restoration of the spatial resolution in SHG images to that closer to the theoretical diffraction limit. The AdvMLE algorithm adaptively and iteratively develops a PSF for the supplied image and succeeds in improving the signal to noise ratio (SNR) for images where the SHG signals are derived from various sources such as collagen in tendon and myosin in heart sarcomere. Approximately 3.5 times improvement in SNR is observed for tissue images at depths of up to ～480 nm, which helps in revealing the underlying helical structures in collagen fibres with an ～26% improvement in the amplitude contrast in a fibre pitch. Our approach could be adapted to noisy and low resolution modalities such as micro‐nano CT and MRI, impacting precision of diagnosis and treatment of human diseases.     

Application of coupled XFEM-BCQO in the structural optimization of a circular tunnel lining subjected to a ground motion

A new structural optimization method of coupled extended finite element method and bound constrained quadratic optimization method (XFEM-BCQO) is adopted to quantify the optimum values of four design parameters for a circular tunnel lining when it is subjected to earthquakes. The parameters are: tunnel lining thickness, tunnel diameter, tunnel lining concrete modulus of elasticity and tunnel lining concrete density. Monte-Carlo sampling method is dedicated to construct the meta models so that to be used for the BCQO method using matlab codes. Numerical simulations of the tensile damage in the tunnel lining due to a real earthquake in the literature are created for three design cases. XFEM approach is used to show the cracks for the mentioned design cases. The results of the BCQO method for the maximum design case for the tunnel tensile damage was matching the results obtained from XFEM approach to a fair extent. The new coupled approach manifested a significant capability to predict the cracks and spalling of the tunnel lining concrete under the effects of dynamic earthquakes.     

Fungal assembly of L-asparaginase using solid-state fermentation: a review

Because of its antitumor therapeutic-activity, as well as its application in food industries to improve the quality,L-asparaginase has attracted considerable attention from several investigators. In recent years, fungi have occupiedadvanced rank among microorganisms in the production process of the enzyme. This review is spotting the light onthe advantages of fungal enzyme and its applications in the food industry and medications. The solid-statefermentation was discussed as the wide alternative and most accepted biosynthesis technique. However, some lightswere also spotted to the statistical experimental design of the fermentation process, mainly on the methodology of theresponse surface for L-asparaginase biosynthesis by fungi. Finally, the immobilization of the enzyme and the featuresof the widely used solid substrates for the maximization of the production process were explored.     

Stability of a Hurwitz polynomial under coefficient perturbations: necessary and sufficient conditions

Necessary and sufficient conditions for a perturbed polynomial to remain Hurwitz are given. The conditions allow considerable freedom in allocating different weights to various coefficients to reflect different levels of uncertainty in the coefficients. The new conditions are an extension of a previous result of the author in which sufficient conditions for the same problem were obtained.     

Phototransients in anodic tantalum oxide thin films

Phototransients under radiation of 274 nm have been studied in anodic tantalum oxide thin films. The area under the phototransient curves, the relaxation time end the decay time are found U> decrease with the applied field. For short times ΔI αexp ( ? t/r) with τ decreasing with field, while for longer times thore is a departure from exponential behaviour. These photo transients may be due to the drift of photoexcited electrons under the action of an applied field end their subsequent retrapping.