Coherent two-dimensional Fourier transform spectroscopy using a 25 Tesla resistive magnet.

We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy

Natural and Synthetic Polymers as Inhibitors of Drug Efflux Pumps

Inhibition of efflux pumps is an emerging approach in cancer therapy and drug delivery. Since it has been discovered that polymeric pharmaceutical excipients such as Tweens® or Pluronics® can inhibit efflux pumps, various other polymers have been investigated regarding their potential efflux pump inhibitory activity. Among them are polysaccharides, polyethylene glycols and derivatives, amphiphilic block copolymers, dendrimers and thiolated polymers. In the current review article, natural and synthetic polymers that are capable of inhibiting efflux pumps as well as their application in cancer therapy and drug delivery are discussed

Characterization of microstructure and corrosion properties of cold worked Alloy 800

X-ray diffraction studies indicated that cold worked (~50%) Alloy 800 was austenitic and transmission electron microscopy revealed the presence of a small volume fraction of hexagonal ε-martensite along with deformation bands, high dislocation density and primary TiN particle with a few dislocations within it. The passivity of cold worked alloy was very stable in H2SO4 solution but unstable in HCl solution at room temperature. The exposure of cold worked alloy in 673 K steam (initial pH of water was 10.1) for a period of 264 h showed almost nil corrosion rate. Scanning electron microscopy revealed a number of small oxide particles on the surface exposed in steam indicating initiation of oxide formation. Energy dispersive X-ray analyses of the surface containing small oxide particles indicated that the surface composition was similar to bulk composition of the alloy. X-ray photoelectron spectroscopy revealed that the alloy surface exposed in steam contained mixed oxides of iron and chromium as well as elemental form of iron, nickel and chromium

Effect of structural defects, surface irregularities, and quenched-in defects on corrosion of Zr-based metallic glasses

X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) revealed a fully amorphous structure for as-cast bulk metallic glass (BMG) and melt-spun ribbons of Zr<SUB>52</SUB>Ti<SUB>6</SUB>Al<SUB>10</SUB>Cu<SUB>18</SUB>Ni<SUB>14</SUB> prepared by copper mold casting and the melt-spinning technique, respectively. For melt-spun ribbons, the wheel-side surface contained a higher concentration of quenched-in defects (air pockets), whereas surface irregularities were noticed in the air side. Fluctuation microscopy indicated more medium-range order for the as-cast structure of BMG than for the melt-spun ribbon, whereas in the BMG, the medium-range order was located more in the central region than in the periphery. Macro- and microcell electrochemical experiments of the BMG along the cross section and macrocell experiments of each side of the ribbons in dilute acidic chloride environments indicated that the corrosion resistance of the BMG decreased with the increase in the medium-range order; the medium-range order, however, was less deleterious than either the surface irregularities or the quenched-in defects from the viewpoint of corrosion. A surface film formed on the metallic glasses in a dilute acidic chloride environment mainly consisted of oxide of zirconium, in which zirconium was present in the Zr<SUP>+3</SUP>, Zr<SUP>+2</SUP>, and Zr<SUP>+1 </SUP>state in the BMG and in the air-side and wheel-side surfaces, respectively

Method to Analyze Three-Dimensional Cell Distribution and Infiltration in Degradable Scaffolds

Effective cell seeding throughout the tissue scaffold often determines the success of tissue-engineering products, although most current methods focus on determining the total number, not the distribution, of the cells associated with tissue-engineering constructs. The purpose of this investigation was to establish a quick, convenient, and efficient method to quantify cell survival, distribution, and infiltration into degradable scaffolds using a combination of fluorescence cell staining and cryosectioning techniques. After cell seeding and culture for different periods of time, seeded scaffolds were stained with a live cell dye and then cryosectioned. Cryosectioned scaffolds were then recompiled into a three-dimensional (3D) image to visualize cell behavior after seeding. To test the effectiveness of this imaging method, four common seeding methods, including static surface seeding, cell injection, orbital shaker seeding, and centrifuge seeding, were investigated for their seeding efficacy. Using this new method, we were able to visualize the benefits and drawbacks of each seeding method with regard to the cell behavior in 3D within the scaffolds. This method is likely to provide useful information to assist the development of novel materials or cell-seeding methods for producing full-thickness tissue grafts

Novel Polymeric Scaffolds Using Protein Microbubbles as Porogen and Growth Factor Carriers

Polymeric tissue engineering scaffolds prepared by conventional techniques like salt leaching and phase separation are greatly limited by their poor biomolecule-delivery abilities. Conventional methods of incorporation of various growth factors, proteins, and/or peptides on or in scaffold materials via different crosslinking and conjugation techniques are often tedious and may affect scaffold's physical, chemical, and mechanical properties. To overcome such deficiencies, a novel two-step porous scaffold fabrication procedure has been created in which bovine serum albumin microbubbles (henceforth MB) were used as porogen and growth factor carriers. Polymer solution mixed with MB was phase separated and then lyophilized to create porous scaffold. MB scaffold triggered substantially lesser inflammatory responses than salt-leached and conventional phase-separated scaffolds in vivo. Most importantly, the same technique was used to produce insulin-like growth factor-1 (IGF-1)–eluting porous scaffolds, simply by incorporating IGF-1–loaded MB (MB-IGF-1) with polymer solution before phase separation. In vitro such MB-IGF-1 scaffolds were able to promote cell growth to a much greater extent than scaffold soaked in IGF-1, confirming the bioactivity of the released IGF-1. Further, such MB-IGF-1 scaffolds elicited IGF-1–specific collagen production in the surrounding tissue in vivo. This novel growth factor–eluting scaffold fabrication procedure can be used to deliver a range of single or combination of bioactive biomolecules to substantially promote cell growth and function in degradable scaffold

Crop Establishment Methods and Integrated Nutrient Management Improve: Part I. Crop Performance, Water Productivity and Profitability of Rice (Oryza sativa L.) in the Lower Indo-Gangetic Plain, India

In the eastern part of India, rice as the most vital staple food crop supports as well the livelihood security of a vast population. Rice is mostly grown under conventional flooded culture without proper nutrient management. Crop performance, water productivity and economic profitability of rice cultivation need to be assessed under water-saving rice production methodologies with proper integrated plant nutrient management strategies using locally available low-cost nutrient sources. A field trial was conducted at the Adaptive Research Farm, Polba (58.57 m msl), Agriculture Department, West Bengal, India, during the rainy/wet seasons of 2014 and 2015 under aerobic culture, the system of rice intensification (SRI) and conventional flooded culture. The experiment was conducted to evaluate the influence of integrated plant nutrition and water-saving rice production methodologies on the crop performance and water productivity of rice and analyse the economic profitability of rice under different nutritional management and crop production methods such as aerobic culture, conventional flooded and SRI with an objective of sustainability in rice cultivation in the agroclimatic region. The results revealed that crop productivity significantly (p ≤ 0.05) varied from 4.68 t ha−1 (average yield recorded under aerobic culture) to 6.21 t ha−1 (average yield as achieved under SRI). Cultivation of rice under aerobic and conventional culture resulted in 24.6% and 20.9% yield reduction respectively as compared to SRI. Integrating 75% of the recommended dose of nitrogen (RDN) through chemicals with 25% RDN from vermicompost resulted in maximum crop productivity irrespective of crop culture. Aerobic rice culture registered maximum water economy in terms of both irrigation water productivity and total productivity. The study concludes that, for maximization of economic profitability, value cost ratio and partial factor productivity of nutrients the SRI method can be adopted along with integrated nutrient management (75% of RDN through chemicals with 25% RDN from vermicompost) in the lower Indo-Gangetic Plain Zone (IGPZ) of West Bengal, India

Tunable femtosecond nonlinear absorption and optical limiting thresholds of La2O3-B2O3 glasses by controlling the borate structural units

Utilization of optical limiting materials to suppress the input intense laser energy is obligatory in a wide variety of applications that deploy the high-power laser sources. In this letter, we demonstrate that the optimization of borate structural units in lanthanum borate (LB) glasses through the addition of various concentrations of heavy metal oxides (HMOs) (PbO and Bi2O3) resulting in achievement of an optimum optical threshold value. The structural changes of these glasses were analyzed by B-11 MAS-NMR and Raman spectroscopic techniques. Nonlinear optical attributes were assessed by the Z-scan technique. The enhancement of two-photon absorption coefficient and decrement in optical limiting threshold factors suggest the LB glasses containing HMOs could be beneficial for power optical limiting devices. The achieved optical limiting threshold values of 0.075 and 0.114 J/cm(2) at 700 and 800 nm, respectively, are superior compared to advanced materials such as nanoparticles, carbon nanotubes, and few-layers of MoS2/Polymethylmethacrylates. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Coherent Two-dimensional Fourier Transform Spectroscopy using a 25 Tesla Resistive Magnet

We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy

3366206.pdf

The supplementary material contains all the atomic force microscopy (AFM) measurements, thickness measurements, and all the transmission, reflection, and Absorption spectra for both materials (experiment and theory)