Order Of Microns Research Articles

Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends.

The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and progression of crazing in all-biopolymeric blends based on Polyhydroxyalkanoates (PHAs). To this end, two chemically different grades of PHA, namely poly(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV), were melt-blended with polybutyrate adipate terephthalate (PBAT). The obtained morphologies of blends, the droplet/fibrillar matrix, were highly influenced by the plasticity of the matrices as well as the content of the minor phase. Increasing the concentration of PBAT from 15 to 30 wt.% resulted in the brittle to ductile transition. It changed the mechanism of plastic deformation from single craze-cracking to homogeneous and heterogeneous intensified crazing for PHB and PHBHV matrices, respectively. Homogeneous tensile crazes formed perpendicularly to the draw direction at the initial stages of deformation, transformed into shear crazes characterized by oblique edge propagation for the PHBHV/PBAT blend. Such angled crazes suggested that the displacement might be caused by shear localized deformation. The crazes' strength and the time to failure increased with the minor phase fibers. These fibers, aligned with the tensile direction and spanning the width of the crazes, were in the order of a few micrometers in diameter depending on the concentration. The network of fibrillar PBAT provided additional integrity for larger plastic deformation values. This study elucidates the mechanism of crazing in PHA blends and provides strategies for controlling it.

Magnetic orderings in BaTi1−xFexO3-δ (with x = 0.1)

We report here various magnetic orderings and Para magnetism in Iron (both56Fe and enriched 57Fe) doped BaTi1−xFexO3-δ (x = 0.1) pristine and Nano-crystalline systems. We tried to establish that oxygen vacancies in different charge states are the key factors for the magnetic behavior of these systems. The samples were prepared by the solid state reaction method and were formed predominantly in tetragonal phase with a trace amount of hexagonal phase. The nascent sizes of the grains were in the micron order. The grains of the pristine sample were refined by mechanical milling. The presence of oxygen vacancies in different charge states and their relative intensities in the pristine and milled samples were investigated by the Photoluminescence Spectroscopic technique in the visible range. Coexistence of ferromagnetic and antiferromagnetic orderings among Fe3+ ions mediated via oxygen vacancies in different charge states was observed through clear sextet patterns in the Mössbauer spectra which was corroborated by SQUID measurements. Whereas increase in oxygen vacancies increased the overall magnetization in these materials, the decrease in grain sizes made the material softer and eventually resulted in single domain formation.

Controlled spherical deuterium droplets as Lagrangian tracers for cryogenic turbulence experiments.

The study of the smallest scales of turbulence by (Lagrangian) particle tracking faces two major challenges: the requirement of a 2D or 3D optical imaging system with sufficiently high spatial and temporal resolution and the need for particles that behave as passive tracers when seeded into the flow. While recent advances in the past decade have led to the development of fast cameras, there is still a lack of suitable methods to seed cryogenic liquid helium flows with mono-disperse particles of sufficiently small size, of the order of a few micrometers, and a density close enough to that of helium. Taking advantage of the surface tension, we propose two different techniques to generate controlled liquid spherical droplets of deuterium over a liquid helium bath. The first technique operates in a continuous mode by fragmenting a liquid jet, thanks to the Rayleigh-Taylor instability. This results in the formation of droplets with a diameter distribution of 2 ± 0.25DN, where DN is the diameter of the jet nozzle (DN = 20μm in the present experiment). This method offers a high production rate, greater than 30kHz. The second technique operates in a drop-on-demand mode by detaching droplets from the nozzle using pressure pulses generated using a piezoelectric transducer. This approach yields a much narrower diameter distribution of 2.1 ± 0.05DN but at a smaller production rate, in the range 500 Hz-2kHz. The initial trajectories and shapes of the droplets, from the moment they are released from the nozzle until they fall 3mm below, are investigated and discussed based on back-light illumination images.

Evaluation of the effect of Ag- doping ZnO microstructure on optical and structural properties and application in photocatalytic properties

The chemical bath deposition technique was successful in producing silver-doped ZnO thin films. On the glass substrates, pure and silver-doped ZnO thin films have been deposited. By using a variety of sophisticated techniques, including X-ray Diffraction (XRD), Field emission Scanning Electron Microscope (FESEM), UV-vis spectrophotometer, and photoluminescence (PL) spectroscopy, the generated pure and Ag-doped ZnO thin films were studied. According to X-ray analysis, Ag-doped ZnO crystallized as a hexagonal wurtzite structure with a preference for growth in the (002) planes, the pure and Ag-doped ZnO's hexagonal wurtzite structures provided evidence for the microparticles' luminescent characteristics. The analysis of the methylene blue degradation revealed that the best photocatalytic response was displayed by the doped ZnO thin film. All thin films' optical bandgaps were broad, and they generally decrease after more doping, it was possible to determine that the particles were elliptical and rod-shaped and that their diameters were on the order of micrometers. for both the doped and pure ZnO microparticles were seen to exist. The outcome shows that the produced microparticles' average grain diameter was determined to be (15,20.5,14.5) um, with noteworthy band gaps of 3.39,3.34 eV, and 3.08 eV, respectively.

Evaluating the optimal tissue thickness for mass spectrometry imaging using infrared matrix-assisted laser desorption electrospray ionization.

Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) utilizes a 2970 nm mid-IR laser to desorb samples with depth resolutions (Z) on the order of micrometers. Conventionally, 5-20 μm thick tissue sections are used to characterize different applications of the IR-MALDESI source, but an optimal thickness has not been systematically investigated. Mouse liver was sectioned to various thicknesses and analyzed using IR-MALDESI mass spectrometry imaging (MSI). Height profiles of tissue sections of various cryosectioned thicknesses were acquired to affirm tissue thickness. Tissue sections of each thickness were measured using a Keyence microscope. Paraffin wax was cryosectioned, mounted on microscope slides, and measured using a chromatic confocal sensor system to determine the cryostat sectioning accuracy. Analyzing sectioned tissues at higher thickness (>10μm) leads to lower ion abundance, a decrease in signal over long analysis times, and more frequent instrument cleaning. Additionally, increasing tissue thickness above the optimum (7μm) does not result in a significant increase in lipid annotations. This work defines an optimal sample thickness for IR-MALDESI-MSI and demonstrates the utility of optimizing tissue thickness for MSI platforms of comparable Z resolution.

Research Status and Development Trend of Piezoelectric Accelerometer

Piezoelectric accelerometers have been widely used because of their large range, simple structure, stable performance, and other advantages. With the improvement of science and technology, the application field is expanding, but there are still some problems in high-temperature environments and low-frequency vibration conditions. Under high-temperature environments, the piezoelectric material will undergo depolarization or resistance change, resulting in sensor failure. Aerospace instruments, water conservancy platforms, and other fields require high-precision instruments with vibration amplitudes of the order of a few microns in the range of 0.01–1 Hz, which require low-frequency and ultra-low-frequency sensors for the measurements. Therefore, how to increase the operating temperature and reduce the noise of piezoelectric accelerometers has become a problem that needs to be solved. This paper reviews the structure, principle, application range, and material selection of piezoelectric components of different types of piezoelectric accelerometers and summarizes the current problems and future research priorities.

Enhancing low-temperature electrochemical kinetics and high-temperature cycling stability by decreasing ionic packing factor

Present-day Li+ storage materials generally suffer from sluggish low-temperature electrochemical kinetics and poor high-temperature cycling stability. Herein, based on a Ca2+ substituted Mg2Nb34O87 anode material, we demonstrate that decreasing the ionic packing factor is a two-fold strategy to enhance the low-temperature electrochemical kinetics and high-temperature cyclic stability. The resulting Mg1.5Ca0.5Nb34O87 shows the smallest ionic packing factor among Wadsley–Roth niobate materials. Compared with Mg2Nb34O87, Mg1.5Ca0.5Nb34O87 delivers a 1.6 times faster Li​+ ​diffusivity at −20 ​°C, leading to 56% larger reversible capacity and 1.5 times higher rate capability. Furthermore, Mg1.5Ca0.5Nb34O87 exhibits an 11% smaller maximum unit-cell volume expansion upon lithiation at 60 ​°C, resulting in better cyclic stability; at 10C after 500 cycles, it has a 7.1% higher capacity retention, and its reversible capacity at 10C is 57% larger. Therefore, Mg1.5Ca0.5Nb34O87 is an all-climate anode material capable of working at harsh temperatures, even when its particle sizes are in the order of micrometers.

Study of Permian Basin Provides Insight Into Parent-/Child-Well Interactions

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211899, “Results From a Collaborative Parent/Child Industry Study: Permian Basin,” by Mark McClure, SPE, ResFrac; Magdalene Albrecht, SM Energy; and Carl Bernet, Ovintiv, et al. The paper has not been peer reviewed. _ The complete paper summarizes results from a collaborative industry study involving seven operators and 10 pad-scale data sets across four different shale plays. The paper specifically focuses on a subset of the data sets from the Midland and Delaware Basins. The project had three main objectives: compare and contrast observations between data sets and basins, develop general insights into parent- and child-well interactions, and provide customized economic optimization recommendations for each individual operator and data set. The simulations reveal that economic performance can be optimized with customized selection of well spacing, job size, and landing depth based on each company’s objectives and price deck. Methods Modeling Approach. The simulations were performed with a fully integrated hydraulic fracturing, wellbore, geomechanics, and reservoir simulator. The entire life cycle of the wells is captured in a single continuous simulation. The fractures are meshed as true cracks, with apertures on the order of microns to millimeters. Constitutive relations are used to capture transitions from being mechanically open to mechanically closed and vice versa. The simulations are fully 3D, and the equations are solved with a fully coupled scheme. For efficiency, the simulations include only one or a few stages along the wells. Fracture geometry is assumed to be planar, with no more than one dominant hydraulic fracture strand propagating per cluster. The modeling approach is based on the industry’s emerging recognition that hydraulic fractures in shale are planar at large scale, while being rough and complex at small scale. In the simulator, constitutive relations are used to account for the effect of small-scale complexity on processes such as proppant transport, fluid leakoff, and fracture propagation. Modeling Work Flow. For each data set, the modeling process consisted of the following steps: 1. Gather and organize data. 2. Create an initial model based on this data. 3. Create a list of key observations from the data set that constitute the objectives for the history-matching process. 4. Present the initial model and the list of key observations to stakeholders to obtain feedback and check communication. 5. Vary simulation input parameters to match the key observations while frequently communicating with stakeholders. 6. After finalizing the history match, perform a set of sensitivity analysis simulations, varying parameters such as well spacing and parent-well age. 7. Set up an economics model and perform a quantitative optimization of net present value (NPV)/section or discounted return on investment [DROI; defined as time-discounted revenue minus time-discounted operating expense divided by time-discounted capital expenditure (CAPEX)]. The steps of this work flow are detailed in the complete paper.

Motion Modelling of the Floating Bushing in an External Gear Pump Using Dimensional Analysis

A new approach to model the motion of floating bushings in external gear pumps is presented in this article, where lubrication conditions have been introduced using dimensional analysis. This model is based on Bond Graph diagrams and has been experimentally validated in lab tests measuring the movement of the floating bushing inside the gear pump by means of laser micrometers. The novelty of this research is the creation of a simple and experimentally validated tool for the behaviour study of these types of pumps, which allows the simulation of a dynamic rigid solid in a fluid boundary with clearances of the order of microns, without using powerful CFD tools, with very short execution times, and using conventional computational tools. The qualitative behaviour of the model with respect to the experimental results is very similar, adjusting the numerical values with very acceptable accuracies by taking into account the precision of the experimental measurements, and allows us to use the model to interpret the volumetric and mechanical efficiency variations according the operating conditions.

Growth, studies of milled and irradiated crystalline samples of DBNT for macro-photonic and electro-mechano functionalities

Single crystals of organic type of NLO crystalline material of DBNT - 8, 9-Dimethoxybenzo[b]naphtho [2,3-d] thiophene are proceeded to be grown by slow evaporation procedure and milled to micro scale and irradiated of Co-60 source of 100 Gy, 500 Gy and 5000 Gy for better scope of classification of system of the monoclinic type of DBNT-pure, micro and irradiated ones. The hardness study specifies the reverse indentation size effect (RISE) with work hardening coefficient above two of all DBNT specimen leads to the micro-tribological workings for springs with proper elastic parameters; the transmittance of DBNT of 5 specimens are 321 nm, 323 nm, 341 nm, 351 nm, and 352 nm for macro, micro, 100 Gy, 500 Gy, 5000 Gy. The photonic utility of identity for 3.86 eV and is 3.8629 eV by the transmittance data. The Non Linear Optical - NLO component this of 1.9, 1.94, 1.95, 1.96, 1.99 times that of KDP from which phase matching provision is enabled the influx property for the DBNT specimens is in the order of microns the (110) and (111) indexing represent for display device configuration. The dielectric behaviour of DBNT shows that polarization properly enabled for all categories by electrical performance, the abnormal variation is due to the vacancies created in the molecule by irradiation.

Quantitative evaluation of refractive index inhomogeneity and its effect on the imaging performance of high-precision injection molded optical lens

High-precision injection molded plastic lenses are gradually substituting the application of glass lenses in advanced imaging and illumination optical systems for their high efficiency and reproducibility. Despite the surface deviation of the plastic lenses having been reduced to micron dimension, the imaging performance of the systems could not be guaranteed. More and more investigations demonstrated that the inhomogeneity of refractive index (RI) variation of plastic lenses was much higher than that of glass lenses. However, the effect of refractive index inhomogeneity on imaging performance is still not well understood, and is not fully considered in the optical design and injection molding process. Thus, an integrated analytical approach was proposed to quantitatively evaluate the inhomogeneity of the refractive index and to reveal its effect on the imaging performance of the optical system. It was found that the inhomogeneity reached 3.44 × 10−3, which was three orders of magnitude higher than that of the glass blank (2.80 × 10−6). Both the magnitude and distribution of refractive index variation significantly degraded the quality and homogeneity of the modulation transfer function (MTF) and spot diagram, from calculated imaging performance considering the inhomogeneity. The maximum MTF was reduced by 60 % compared with the design value. Comparative investigation also demonstrated that refractive index inhomogeneity had an equivalent effect on the imaging performance in comparison with the micron order surface deviation. Reducing the degradation of refractive index inhomogeneity provides an efficient way to improve the imaging performance of advanced optical systems.

Self-compensation methodology for ultrasonic thickness gauges

There are many causes for the reduction of the thickness in pipelines, tanks and other mechanical structures. Corrosion, erosion, and abrasive wear cause degradation of mechanical structures and decrease their lifespan. These can be very slow processes that are difficult to track over time. Thickness gauging monitoring is commonly used as a way of preventive maintenance. The pulse-echo ultrasound can be a suitable technique to measure the thickness diminution in industrial facilities. Although ultrasound is considered a robust technique, in this particular application it presents two main difficulties: the mechanical stability of the assembly and the variation of the ultrasonic speed over time. Both mechanical assembly and acoustic propagation speed are strongly influenced by the temperature. In this paper, the implementation of a methodology that compensates for the temperature influences on the ultrasonic speed and the mechanical assembly is presented. The methodology can be applied in metallic structures to evaluate corrosion over long time periods. The temperature compensation data is obtained from the analysis of the ultrasonic signals. In this sense, the method can be called self-compensated. As initial data for the determination of thickness changes, the ultrasonic speed in the material at a reference temperature must be known. All results are evaluated at this temperature. An analysis of the uncertainty sources and limitations of the methodology is also included. To show the experimental application of the proposed technique, a rigid sample was designed in order to avoid mechanical instability. The results show that the methodology can compensate for the temperature, detecting a thickness reduction in the order of a few micrometers.

Study of Particle Size Measurement by the Extinction Method in Flame

The laser extinction method (LEM) is particularly suitable for measuring particle sizes in flames because this method, which is based on the Beer–Lambert law, is non-intrusive and easy to implement. In the LEM, the interpretation of the extinction data is usually developed under the assumption that light extinction due to scattering is a result of the superposition of single scattering by individual particles; however, this could be violated for flames with dense concentrations of particles in which multiple scattering could occur. Quantifying the effect of multiple scattering under general conditions is still a formidable problem. In this work, we carried out a series of careful measurements of the laser extinction using standard particles of various known sizes, number densities and optical path lengths, all under the condition that the acceptance angle of the detector was limited to nearly zero. Combined with a four-flux model, we quantitatively analyzed the effect of multiple scattering on the size measurement using the LEM. The results show that the effect of multiple scattering could be ignored when the optical thickness is less than two under strict restrictions on the detector acceptance angle. Guided by this, the size distribution of an alumina (Al2O3) particle sample was measured by the LEM with dual wavelengths. Parameterized distributions were solved with the help of graph plotting, and the results compared well with the measurement from the Malvern particle size analyzer. The same method was then used to measure the particle size distribution in the plume of a solid rocket motor (SRM). The use of an off-axis parabolic mirror in the experimental setup could suppress the jitter of light passing through the SRM plume, and the particle size in the plume of the measured SRM was in the order of microns.

AFM-IR for Nanoscale Chemical Characterization in Life Sciences: Recent Developments and Future Directions.

Despite the ubiquitous absorption of mid-infrared (IR) radiation by virtually all molecules that belong to the major biomolecules groups (proteins, lipids, carbohydrates, nucleic acids), the application of conventional IR microscopy to the life sciences remained somewhat limited, due to the restrictions on spatial resolution imposed by the diffraction limit (in the order of several micrometers). This issue is addressed by AFM-IR, a scanning probe-based technique that allows for chemical analysis at the nanoscale with resolutions down to 10 nm and thus has the potential to contribute to the investigation of nano and microscale biological processes. In this perspective, in addition to a concise description of the working principles and operating modes of AFM-IR, we present and evaluate the latest key applications of AFM-IR to the life sciences, summarizing what the technique has to offer to this field. Furthermore, we discuss the most relevant current limitations and point out potential future developments and areas for further application for fruitful interdisciplinary collaboration.

An Electrochemical Perspective on the Interfacial Width between Two Immiscible Liquid Phases.

Molecular dynamics simulations and vibrational sum-frequency spectroscopy are historically the main techniques applied to the description of the molecular structure and dynamics of the immiscible liquid/liquid interface. A molecular sharpness is estimated for oil/water interfaces, with an interfacial width that extends from hundreds of Å to 1 nm. However, electrochemical studies have elucidated a deeper liquid/liquid interface on the order of several micrometers. The breaking down of single-entity electrochemistry to simpler systems and the combination of high-resolution microscopies is confirming a larger extension of the interface. What can be the role of the electrochemist in clarifying this fundamental question? We try to give a suggestion at the end of a brief historical overview of the liquid/liquid interface studies.

Critical Role Played by Interface Engineering in Weakening Thickness Dependence of Superconducting and Structural Properties of FeSe0.5Te0.5-Coated Conductors.

Increasing the thickness of a superconducting layer and simultaneously reducing the thickness effect in iron-based superconducting coated conductors are particularly essential for improving the critical current Ic. Here, for the first time, we have deposited high-performance FeSe0.5Te0.5 (FST) superconducting films up to 2 μm on LaMnO3-buffered metal tapes by pulsed laser deposition. An interface engineering strategy, alternating growth of a 10 nm-thick nonsuperconducting FST seed layer and a 400 nm-thick FST superconducting layer, was employed to guarantee the crystalline quality of the films with thicknesses of the order of micrometers, resulting in a highly biaxial texture with grain boundary misorientation angle less than the critical value θc ∼ 9°. Moreover, the thickness effect, that the critical current density (Jc) shows a clear dependence on thickness as in cuprates, is reduced by the interface engineering. Also, the maximum Jc was found for a 400 nm-thick film with 1.3 MA/cm2 in self-field at 4.2 K and 0.71 MA/cm2 (H∥ab) and 0.50 MA/cm2 (H∥c) at 9 T. Anisotropic Ginzburg-Landau scaling indicates that the major pinning centers vary from correlated to uncorrelated as the film thickness increases, while the thickness effect is most likely related to the weakening of flux pinning by the fluctuation of charge-carrier mean free path (δl) and strengthening of flux pinning caused by the variation of superconducting transition temperature (δTc) due to off-stoichiometry with thickness.

Piezoviscous-polar lubrication of capillary compensated hybrid conical undulated journal bearing

Linear harmonic vibration during machining of a conical journal may produce micron order undulations on outer surface of journal. Further, a lubricant comprising of long chain polymer additives may attain polar effect due to couple stresses. At high pressure conditions, pressure viscosity interaction in oil may affect the actual viscosity of the lubricant. The flow behaviour of piezoviscous-polar lubricant in a conical bearing is modelled in cylindrical coordinates. FE analysis is utilized to solve the modified Reynolds equation. The results indicate that journal undulations offer relatively higher oil film pressure due to local convergence in oil film, consequently exhibit higher stiffness coefficients. Moreover, piezoviscous-polar lubricant may raise the values of S¯zzupto 18% and C¯zz upto 32% than Newtonian lubricant.

Light field analysis for modeling and transmission characteristics of partially coherent light-emitting diodes

When analyzing the transmission characteristics of LEDs for long-distance lighting and communication applications, the light field is commonly assumed to be fully incoherent. However, in reality, the LED light source emits partially coherent light with a spatial coherence length on the order of microns. This paper is based on the generalized higher-order Lambert model of LEDs and aims to construct a Gaussian-Schell model for the LED beam (LED-GSM) on the near-field source plane, with a half-power angle of no more than 10o. Utilizing the cross-spectral density function transmission theory for partially coherent light, this paper provides the LED-GSM model’s spatial coherence length and beam radius at different distances and designs an experiment for measuring the spatial coherence length of LED beams. Experimental measurements of the spatial coherence length and beam spot size of LED beams at different distances are carried out using a Thorlabs LED528EHP light source. The experimental results match well with the theoretical simulations of the LED-GSM model, thus validating its effectiveness. Then, the proposed LED-GSM model is utilized to investigate the long-distance transmission characteristics of partially coherent narrow-beam LED light. Simulation results indicate that the spatial coherence length of the LED light field can reach tens to hundreds of millimeters over transmission distances of several kilometers. The beam radius is much smaller than that of the beam radius based on the fully incoherent model, and the beam intensity distribution also displays distinct differences.

High-resolution characterization of the coagulation and drying processes of whole blood based on optical coherence tomography

Introduction: Escaping whole blood exhibits biochemical and physical coupled mechanisms such as coagulation and drying. However, there is no method for simultaneously monitoring the coagulation and drying procedure.Methods: In this study, a new method based on optical coherence tomography (OCT) combined with speckle variance and thickness is presented for simultaneously capturing spatially high-resolved characteristics of coagulation and drying of whole blood during the procedure. Deep learning based on a convolutional neural network (CNN) is employed for collecting OCT images with a resolution of micron order and quantitatively obtaining pixel-wise information of whole blood.Results and discussion: Then, the pixel-wise thickness map provides high-resolved temporal–spatial dynamics of whole blood during the drying procedure, and the corresponding speckle variance can uncover information of whole blood coagulation. The results demonstrate that coagulation and drying of whole blood have spatially inhomogeneous features. This method could provide the potential for revealing the coupling mechanism between coagulation and drying.

Thermo-fluid-dynamics of inverse Leidenfrost levitation of small liquid/solid spheres over liquid pools

The present study provides a detailed theoretical investigation of the thermo-fluid-dynamics of the inverse Leidenfrost levitation phenomenon of a microscale droplet/solid on a liquid pool, and also the conditions essential for solid/liquid spherical objects to levitate. The theoretical model is developed for the floating characteristic of liquid/solid objects based on the thermo-fluid-dynamics of the vapor film during the inverse Leidenfrost effect. A very small thickness of the vapor layer, approximately of the order of micrometers, formed between the object and liquid pool during levitation, and its variation with the angular position and time history is considered in contrast to previous works. The actual magnitude of the overlapping contact angle is estimated and also incorporated in the present study. The effects of various influencing parameters, like nondimensionalized sphere radius, contact angle, and density ratio, on the levitation possibility and dynamics, are analyzed. The model is validated against experimental observations of the inverse Leidenfrost phenomenon for water drop levitating on a nitrogen liquid pool, and the effects of droplet parameters on total levitation time and dynamics are noted to provide accurate predictions. The approach presented is noted to provide a more accurate estimate of inverse Leidenfrost levitation compared to previous reports.