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Liquid microbial inoculants (LMIs) can play a paramount role in integrated nutrient management as these are renewable and eco-friendly sources of plant nutrition. Here, we evaluated the impact of LMIs, such as of Stenotrophomonas maltophilia and Azotobacter sp., on the growth and yield parameters of cluster bean (Cyamopsis tetragonoloba (L.) Taub.). The bacterial culture, S. maltophilia, was isolated from the nodules of cluster bean and identified by sequencing the 16SrRNA gene. On applying LMIs and 75% recommended dose of fertilizer (RDF) (T7), a significant improvement in plant height, dry fodder yield and seed yield was observed. Besides, there was a ~ 10% increase in all the other growth and yield attributes, such as no. of branches, no. of pods, pod length, no. of grains per pod, and 1000-grain weight. The increase in seed yield and dry fodder yield with T7 over the T1 (RDF) was 16% and 19%, respectively. Moreover, the total energy output of different treatments as computed from the main products ranged from 69,973.5 to 82,490.1 MJha−1. This might be due to higher seed and dry fodder yield with LMIs. The different LMI treatments increased the net returns of cluster beans over the control (T7, US$ 527.91). The soil analysis revealed the improvement in macro (N, P and K) and micronutrients (Fe, Cu, Zn and Mn) by 10–20% after the LMI treatments. Thus, priming seeds with LMIs could be an effective strategy to stimulate the growth of cluster beans without compromising the soil fertility.

The advancements in producing interactions of concentrated energy fluxes, such as femtosecond lasers and high-energy electron beams with the absorbing substances, have facilitated new discoveries and excitement in various scientific and technological areas. Since their invention, significant improvements in temporal, spatial, energetic, and spectroscopic characteristics have been realized. Due to the ultrashort pulse width and higher intensity (1012 W/cm2), it is possible to ablate the materials with negligible damage outside the focal volume, thereby allowing the treatment of biological samples, such as live cells, membranes, and removal of thin films, as well as bulk materials for many applications in diverse fields, including micro-optics, electronics, and even biology under extremely high precision. Since most biological systems are transparent toward the NIR spectral range, it follows the nonlinear multi-photon absorption interaction mechanism. In contrast, the electron beam follows linear absorption mechanism for material modifications even at lower energies. For realizing the fs-laser nano-processing in material applications, such as silicon microchips, or in biology like retinal cells, it is crucial to find a way to deliver these pulses precisely at the site of action and enhance the selectivity. The utilization of electron beams in material modification has also been exercised widely to attain nanoscale precision. In the next section, biological materials, such as cornea, retina, and silk, are discussed.

Attosecond delay lines are key to enable time-resolved measurements on atoms, molecules, plasma and solid-state materials. This tutorial review presents the current status of a wide variety of attosecond delay lines operating from the infrared to the X-ray spectral region. Depending on the wavelength regime of the pump and probe pulses, we have divided attosecond delay lines into four broad categories: IR–IR, XUV–IR, XUV–XUV and X-ray–X-ray delay lines. Further, the designs differ as to whether they are based on amplitude division or wavefront division of the laser beam. We discuss the design ideas, compactness, calibration and stability of various attosecond delay lines and compare their performance in corresponding experiments. Applications of the delay lines to resolve selected attosecond phenomena are shown along with future perspectives towards achieving zeptosecond resolution.

We exploit the nonlinear multiphoton interaction of a few-cycle femtosecond (fs) pulse with viscoelastic microfibers in order to produce nanoscale grooves on its surface. The single fs pulse has been extracted from 1 kHz pulse train by double-shutter gating technique by placing two mechanical shutters in the beamline and simultaneously triggering them with a controlled delay. With adjustment of the time delay between two shutters, a small transmission window has been created to cleanly extract a single or desired number of pulses. We found that the single-pulse ablation threshold for microfiber is $$1 \hbox { J}/\hbox {cm }^2$$ while for absorbing surfaces like crystalline Si is $$0.01 \hbox { J}/\hbox {cm}^2$$. Precise diffraction unlimited ablation of materials opens a route to process nanoscale waveguides, microfluidic devices to isolate cells or macro-molecules.

We fabricated ultra-thin glass cantilevers using femtosecond laser pulses while integrating nitrogen vacancy (NV) centers at its tip. The magneto-mechanical coupling of electron spins in integrated NV center’s was exploited for quantum sensing applications.

We fabricated ultra-thin glass cantilevers using femtosecond laser pulses while integrating nitrogen vacancy (NV) centers at its tip. The magneto-optical susceptibility of NV centers towards electron spin was exploited for quantum sensing applications.

We demonstrate a simple and versatile nanomechanical force measuring setup with 1 nN precision in air and vacuum using a load cell of an ultra-microbalance. We validate stability, precision, and linearity of the load cell with simple tests. The setup is customized to measure stress-strain response of biomaterials (silk, leaf, and flower) and capillary force in fluids. We isolated an optical pull force induced by a Watt-level laser reflected from a mirror/solid surface in air, in addition to optical push force. Furthermore, we add an interferometric probe to directly measure nanoscale deflection of cantilever of the load cell in real-time, thus bypassing its conventional electromagnetic readout, to improve speed and precision of the instrument. We demonstrate nanomechanical force measurement in high vacuum with the same precision and employ radiation pressure to calibrate the load cell for various precision measurements.

When an intense femtosecond (fs) pulse non-linearly interacts with ionizing matter, it leads to the generation of bursts of extreme ultra violet (XUV) coherent irradiations having ultrashort pulse duration in attoseconds. Here, we present systematic experiments to show how the high-order harmonics generation is modulated with a spatially shaped fs-laser beam. The spatial shaping of fs-pulses has been induced with the alteration in hard aperture from 8-25 mm diameter. The experimental parameters such as incident power and gas pressure has been optimized to efficiently generate the harmonics in our system. While changing the aperture size of intense fs-beam, we observed unique space-time coupling effects in the shapes of individual harmonics beam.

We introduce an ultra-thin attosecond optical delay line based on controlled wavefront division of a femtosecond infrared pulse after transmission through a pair of micrometer-thin glass plates with negligible dispersion effects. The time delay between the two pulses is controlled by rotating one of the glass plates from absolute zero to several optical cycles, with 2.5 as to tens of attosecond resolution with 2 as stability, as determined by interferometric self-calibration. The performance of the delay line is validated by observing attosecond-resolved oscillations in the yield of high harmonics induced by time delayed infrared pulses, in agreement with a numerical simulation for a simple model atom. This approach can be extended in the future for performing XUV-IR attosecond pump–probe experiments.

We employ a femtosecond light sheet generated by a cylindrical lens to rapidly produce high-fidelity nano-structures over large area on silicon surface. The Fourier analysis of electron microscopy images of the laser-induced surface structures reveals sharp peaks indicating good homogeneity. We observed an emergence of second-order spatial periodicity on increasing the scan speed. Our reliable approach may rapidly nano-pattern curved solid surfaces and tiny objects for diverse potential applications in optical devices, structural coloring, plasmonic substrates and in high-harmonic generation.

Spider silk is a tough, elastic and lightweight biomaterial, although there is a lack of tools available for non-invasive processing of silk structures. Here we show that nonlinear multiphoton interactions of silk with few-cycle femtosecond pulses allow the processing and heterostructuring of the material in ambient air. Two qualitatively different responses, bulging by multiphoton absorption and plasma-assisted ablation, are observed for low- and high-peak intensities, respectively. Plasma ablation allows us to make localized nanocuts, microrods, nanotips and periodic patterns with minimal damage while preserving molecular structure. The bulging regime facilitates confined bending and microwelding of silk with materials such as metal, glass and Kevlar with strengths comparable to pristine silk. Moreover, analysis of Raman bands of microwelded joints reveals that the polypeptide backbone remains intact while perturbing its weak hydrogen bonds. Using this approach, we fabricate silk-based functional topological microstructures, such as Mobius strips, chiral helices and silk-based sensors.

We introduce special mechanical shutters for extraction of single femtosecond (fs) pulse from fs- pulse train (1 KHz). Extracted pulse could be utilized to study time resolved dynamics at atomic or bulk scale especially in case of XUV pulses.

We investigated selective reduction of angiogenesis based on ultrafast laser. Using transgenic zebrafish embryos and model animal, we have demonstrated that the method is very effective for a selective reduction of angiogenesis in vivo.

In summary, all the observations from the present work reveals that fs-laser irradiation on pollen walls to make an evident physical hole with an outside diameter of about 1 m well conserves the physiological state of the cell including its viability and pollen tube germination capability. Furthermore, from the successful delivery of foreign DNA into pollen through the hole reveals that the current method has an evident potential in the field of plant genetic engineering. Topographical imaging as well as optical imaging of the plasma membranes led us to observe a self-healing process for live cells within several minutes of time after the fs-laser ablation on the live cells. A simple viscoelastic model for both the hole opening and closing process was found to be applicable to interpret its dynamics. The very slow dynamics could be explained in terms of high surface viscosity due to the presence of cytoskeleton network bound to the plasma membrane. The irregular feature in plasma topography observed in the final stage of the healing process might be due to a slice of the assembled lipid, which resulted from the reconstruction of not only the plasma membrane itself but also F-actin network as a cytoskeleton structure of live cells. Although two-dimensional plug flow model adapted in the current work fairly well interpret the experimental observations in macroscopically, the presence of transmembrane proteins, transbilayer interactions, and adhesion sites, etc., in addition to the bound cytoskeleton structure, produces a variety of restrictions on the flow dynamics of the plasma membrane through an alterations in many microscopic physico-chemical properties including thickness and hydrodynamic properties of the fluidic films. We have developed a new method for elucidating more exact mechanism on the interesting topic of self-healing process based on ultrafast laser perforation of the plasma membrane of the animal cell. A mechanical stimulus to live-cell plasma membrane by the induced surface

We have investigated the effect of the dynamics of crater size on the poly(dimethylsiloxane) (PDMS) surface morphology in fs-laser micro-processing. PDMS surface was processed with varying both inter-pulse interval and inter-spot distance between successive laser pulses. With keeping the interval of 5 ms crater shape is round even if the spot is overlapped in space. But decreasing the interval to 0.02 ms the shape of the crater is no longer round. Decreasing the inter-distance between the craters results in roughened surface morphology even at time intervals of 5 ms. Temporal dependence of single-shot fs-laser induced crater size was measured as a function of time delay. Within 0.1 ms after pulse irradiation with a fluence of 4.8 J/cm(2) on PDMS surface the crater size has reached to its maximum values and then decreased with a time constant of about 0.3 ms. The surface morphology after fs-laser pulse irradiation is strongly dependent on not only inter-spot distance between successive laser pulse but also their inter-pulse intervals. By proposing a theoretical model on their dynamic features, we will try to explain the current observation in quantitatively. (C) 2015 Optical Society of America

Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2-8.6 J/cm(2). The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm(2). Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.