Properties Of Micro Research Articles

Effects of adhesive and frictional contacts on the nanoindentation of two-dimensional material drumheads

Nanoindentation of suspended circular thin films, dubbed drumhead nanoindentation, is a widely adopted technique for characterizing the mechanical properties of micro- or nano-membranes, including atomically thin two-dimensional (2D) materials. This method involves suspending an ultrathin specimen over a circular microhole and applying a precise indenting force at the center using an atomic force microscope (AFM) probe. Classical solutions assuming a point load and a fixed edge, which are referred to as Schwerin-type solutions, are commonly used to estimate Young’s modulus of the membrane material out of load–deflection measurements. However, given the widespread experimental evidence for adhesive and frictional contacts between the probe tip and the membrane, as well as sliding between the membrane and its supporting substrate, quantitative investigations of the effects of these interactions are required. In this paper, we formulate a boundary value problem to rigorously model such effects, ensuring relevance to experimental operations. Our numerical analyses reveal that the adhesive effect at the tip-membrane interface diminishes as the indentation depth increases or the tip size decreases. Furthermore, frictional interactions at this interface shift the maximum membrane stress from the center to the tip-membrane contact line with increasing indentation depth and interfacial shear stress. At large indentation depths, the size of the indenter tip and the sliding of the membrane-substrate are found to have a large effect on the indentation load–deflection relationship. Thus, we propose a new approximate formula for this relationship assuming a non-adhesive and frictionless spherical tip of a finite radius and a slippery contact with the supporting substrate. This formula is more accurate than the widely used Schwerin-type solution. It can be used to simultaneously extract the in-plane stiffness of the membrane and the shear strength at the membrane-substrate interface.

New trends in the valuation of micro and nanocrystalline cellulose and their derivatives extracted from the wastes of palm frond for curing of peptic ulcers

The current study was directed to explore new natural products that alleviate inflammation with the least harming effects on the gastric mucosa. This study examined the anti-ulcerative properties of micro and nanocrystalline cellulose (MCC, NCC) palm frond and their chemically modified samples (sulfated (SMCC and SNCC), methylated (MMCC and MNCC) and phosphorylated (PMCC and PNCC)). The lowest prebiotic index (I) was recorded in case of the MMCC and MNCC extract with L. Reuteri (I = 1) while the higher prebiotic index was recorded in case of the PMCC against L. casei (I = 3.7). All treated groups showed significant improvements in the ulcer scores (P < 0.05) compared to the control (indomethacin) group. However, MMCC showed marked effects similar to ranitidine. A significant decrease was found in pro-inflammatory cytokines (IL-6 and TNF-α) and pro-apoptotic gene (Bax) in all treated groups compared to the ulcer-induced group. In conclusion, the histopathological evaluation of MNCC, PNCC and SNCC had superior ameliorating effect on gastric ulcer induced in rats when compared to Omeprazole 20 mg/kg and other treated groups (MMCC, PMCC, SMCC).

Nature-Inspired Micro/Nano-Structured Antibacterial Surfaces.

The problem of bacterial resistance has become more and more common with improvements in health care. Worryingly, the misuse of antibiotics leads to an increase in bacterial multidrug resistance and the development of new antibiotics has virtually stalled. These challenges have prompted the need to combat bacterial infections with the use of radically different approaches. Taking lessons from the exciting properties of micro-/nano-natural-patterned surfaces, which can destroy cellular integrity, the construction of artificial surfaces to mimic natural functions provides new opportunities for the innovation and development of biomedicine. Due to the diversity of natural surfaces, functional surfaces inspired by natural surfaces have a wide range of applications in healthcare. Nature-inspired surface structures have emerged as an effective and durable strategy to prevent bacterial infection, opening a new way to alleviate the problem of bacterial drug resistance. The present situation of bactericidal and antifouling surfaces with natural and biomimetic micro-/nano-structures is briefly reviewed. In addition, these innovative nature-inspired methods are used to manufacture a variety of artificial surfaces to achieve extraordinary antibacterial properties. In particular, the physical antibacterial effect of nature-inspired surfaces and the functional mechanisms of chemical groups, small molecules, and ions are discussed, as well as the wide current and future applications of artificial biomimetic micro-/nano-surfaces. Current challenges and future development directions are also discussed at the end. In the future, controlling the use of micro-/nano-structures and their subsequent functions will lead to biomimetic surfaces offering great potential applications in biomedicine.

Micromechanical properties of micro- and nanocrystalline CVD diamond thin films with gradient microstructures and stresses

Chemical vapor deposition produced diamonds attract considerable scientific and industrial interest due to their exceptional mechanical and functional properties. Here, hot filament (HF) chemical vapor deposition was used to synthesize two diamond thin films with different cross-sectional microstructure and residual stresses. Structural characterization by scanning electron microscopy, Raman spectroscopy, and cross-sectional synchrotron x-ray nanodiffraction revealed different diamond morphologies. While the microcrystalline diamond film exhibits pronounced microstructural gradients expressed by gradually increasing (i) intensities of the 111 Debye-Scherrer rings, (ii) ⟨110⟩ fiber texture sharpness, (iii) grain size, and (iv) slightly oscillating residual stress at the level of −0.5 GPa, the nanocrystalline diamond film showed no pronounced cross-sectional variation of microstructure above the nucleation zone of ∼0.5 μm and a steady stress level of 0.25 GPa. In situ micromechanical cantilever bending tests revealed highly different mechanical properties of the two films. In detail, Young's modulus of 830 ± 53 and 459 ± 53 GPa, fracture stress of 12.4 ± 0.8 and 7.8 ± 1.0 GPa, and fracture toughness values of 6.9 ± 0.4 and 3.6 ± 0.3 MPa⋅m½ were evaluated for the micro- and nanocrystalline diamond films, respectively. In summary, this study provides valuable insights into the microstructure-residual stress correlation in micro- and nanocrystalline diamond films, especially illuminating their influence on micromechanical properties.

In Situ Thermoelectric Property Characterization of Microscale Single Thermoelectric Fiber Based on Harmonic Detection

Exploring advanced thermoelectric materials, especially flexible thermoelectric fibers, is promising for wearable devices. The thermoelectric properties of these fibers are evaluated using the figure of merit ZT value. However, there is a lack of empirical research on the properties of microscale thermoelectric fibers, necessitating the development of precise measurement methods. In addition, since the properties of micro- and nanofiber materials can be affected by the microstructure, separate measurements of electrical conductivity, Seebeck coefficient, and thermal conductivity before calculating the ZT values can lead to large errors in the final calculations. In this study, Bi 2 Te 2.7 Se 0.3 thermoelectric fibers are prepared and measured by using a thermally drawn method and an in situ method, respectively. The in situ measurements are carried out using a self-developed instrument capable of measuring temperatures from room temperature up to 1,200 K, suitable for sample sizes ranging from micro- to nanoscale. The uncertainty of the measurement exhibits less than 6.36%. The results indicate that the thermal drawing process influences crystal growth, enhancing the Seebeck coefficient and reducing electrical conductivity and thermal conductivity. Moreover, the accuracy of the measurement method is verified by pure Pt wire. The integrated in situ measurement effectively reduces experimental errors due to sample differences when calculating parameters for multiple samples measured individually, and the maximum error that can be reduced is 19.5%. This research contributes a practical measurement method of thermoelectric fibers and advances the development of wearable thermoelectric devices.

Environmental aspects of the application of mineral fertilizers

To increase crop production, it is practically important to study the influence of micro fertilizers in the context of organic fertilizers (compost). The effect of micro fertilizers on the yield, quality, and chemical composition of the fruit of the pepper variety was studied in a compost-based cropping trial. It was found that the combined use of organic and micro fertilizer increased pepper yield by 6.67-19.37%. The sugar content in the optimum varieties increased by 1.07-1.31 times, vitamin C by 1.01-1.14 times, ash by 1.02-1.17 times, and cellulose by 1.06-1.44 times compared to the background. The influence of different concentrations of trace element salts on the chemical composition of pepper fruits was also studied. The concentration and chemical properties of micro fertilizing salt solutions were found to influence both the content and accumulation of TE in pepper fruits.

Bayesian-optimized random forest prediction of key properties of micro-/nanofibrillated cellulose from different woody and non-woody feedstocks

The scale-up of nanocellulose production, a still challenging task, could benefit greatly from machine learning. In this paper, random forest regressors were applied to predict two important parameters for nanocellulose processing: nanofibrillation yield and aspect ratio. The dataset comprised diverse pulp sources, ranging from non-woody and woody feedstock, and two different types of pulp pre-treatments, namely mechanical refining and enzymatic hydrolysis. The obtained models were evaluated in terms of number of features and optimized with regard to some important hyperparameters, using the Bayesian optimization function from the SkOpt library. Considering the heterogeneity of the data, the prediction of both aspect ratio and yield of nanofibrillation was deemed satisfactory. For the former, R² scores of 0.986, 0.902 and 0.932 were obtained for the training, validation and testing subsets, respectively. Regarding the latter, R² scores of 0.994, 0.947 and 0.877 were achieved for the same types of subsets. Other important remarks are that enzyme dosage was the most important feature for predicting aspect ratio, while it did not play an important role for yield modelling. For this output, the transmittance at 600 nm accounted for almost 90% of the total feature importance.

A comprehensive review on the impact of micro and nano palm oil fuel ash in cementitious material

The supplementary cementitious material (SCM) has been introduced as a cement replacement in the concrete or mortar mix design for reducing the emission of carbon gases during the manufacturing of cement. Palm oil fuel ash (POFA) is one of the potential agricultural wastes SCM that is rich in silica content and can be used as cement replacement. However, the inconsistent particle characteristic of the raw POFA due to the uncontrolled incineration condition brings deterioration effect in the concrete’s fresh and mechanical properties. Therefore, many papers conducted fineness reduction approach and other treatment processes to produce the micro and nano scale POFA as a suitable cement replacement. This article aims to provide a comprehensive understanding of the impact of micro and nano palm ash on cementitious materials properties, focusing on the potential of nano palm ash for future work. A detailed comparison is made between the treatment process, chemical and physical properties of micro and nano palm ash, later focuses on the fresh and hardened properties of various sizes of POFA-based concrete and mortar. Nano palm ash has a smaller particle size, higher silica content, and lower unburnt carbon than micro palm ash, resulting in improved fresh properties and early age-hardened properties of concrete when using nano palm ash.

Thermal and Surface Area Properties of Micro and Nano Sized Pumice

Raw pumice samples were modified with nano carbon black, borax, and nano carbon-borax using the sol-gel method by applying surface modification processes, and the changes in the thermal behavior of the surface modification of the raw pumice were studied by characterizing them with FE-SEM, EDX, FT-IR, XRD, BET and TGA-DTA. In the analyses made with FE-SEM, it was observed that the surface and pore structure of the raw pumice changed after the modified process, and in the EDX analysis, it was determined that nano carbon black and borax adhered to the surface of the raw pumice. In the XRD results, no change in the crystal structure of the raw pumice was observed after the modified treatment. TGA-DTA analysis showed that the mass loss of raw pumice (P) was greater than pumice-nano carbon black (PC), pumice-borax (PB), and pumice-borax-nano carbon black (PBC). Accordingly, raw pumice showed a mass loss of approximately 25%, pumice-borax (PB) and pumice-nano carbon black (PC) 0.45%, and pumice-borax-nano carbon black (PBC) nearly 3%. According to the BET analysis results, it was determined that the raw pumice has a surface area of 28.126 m2/g. After the surface modification process, the surface area of the raw pumice was determined as 52.127 m2/g in the pumice-nano carbon black sample, 49.125 m2/g in the pumice-borax sample, and 32.523 m2/g in the pumice-borax-carbon black sample. Considering the data obtained, the best surface properties were showed in pumice-nano carbon black (PC). Research results showed that; the modification process with nano carbon black and borax changed the thermal behavior of raw pumice.

3D Strain Measurement of Heterostructures Using the Scanning Transmission Electron Microscopy Moiré Depth Sectioning Method.

The mechanical properties of micro- and nanoscale materials directly determine the reliability of heterostructures, microstructures, and microdevices. Therefore, an accurate evaluation of the 3D strain field at the nanoscale is important. In this study, a scanning transmission electron microscopy (STEM) moiré depth sectioning method is proposed. By optimizing the scanning parameters of electron probes at different depths of the material, the sequence STEM moiré fringes (STEM-MFs) with a large field of view, which can be hundreds of nanometers obtained. Then, the 3D STEM moiré information constructed. To some extent, multi-scale 3D strain field measurements from nanometer to the submicrometer scale actualized. The 3D strain field near the heterostructure interface and single dislocation accurately measured by the developed method.

Determination of the resistance of water-repellent properties to ultraviolet radiation on self-hydrophobized surface textures of AISI 304 steel

In this work, the object of the study were femtosecond laser textured steel samples. Using a femtosecond laser to texture the surface both in the direct-beam mode, which provides microtextures, and in the reflection mode, which leads to the formation of LIPSS-type nanostructures on the surface. Such hybrid complexes are optimal in terms of water repellency as they embody the principle of hierarchical textures. This approach is one of the promising ways to solve the problem of scaling the process of obtaining superhydrophobic metal surfaces. The aim of the work is to establish the stability of water-repellent properties of micro- nanotextures obtained on the surface of AISI 304 steel after spontaneous hydrophobization under the action of UV radiation. The study of the obtained textured surface by scanning electron microscopy to confirm the presence of nanotexture and by energy-dispersive X-ray spectroscopy to establish the elemental composition of the obtained microtexture were made in the work. The paper shows that the water repellency of AISI 304 steel surfaces textured at micro and nano levels by femtosecond laser after long exposure to the atmosphere increases to a superhydrophobic state with the value of contact angles up to 155°. It has been shown that such surfaces are sensitive to UV radiation. Depending on the type of structure, the loss of hydrophobicity under experimental conditions occurs in 15-45 minutes of exposure, and complete hydrophilization of the surface occurs after 100 minutes of irradiation. As a result, the obtained self-hydrophobic surfaces are not suitable for operation under the influence of sunlight. However, ultraviolet radiation can be used to pre-clean such surfaces from adsorbed organic contaminants.

Multi-Bessel Beams Generated by an Axicon and a Spatial Light Modulator for Drilling Applications

We report on an optical setup to generate multi-Bessel beam profiles combining a refractive axicon and a spatial light modulator. Based on their particular beam profile, Bessel beams offer advantageous properties for micro drilling processes and internal volume processing, especially for transparent materials. In addition, the laser power of industrial, ultrashort pulsed lasers has increased significantly over the last few years, offering the possibility for highly efficient processes using multi-spot profiles. Our optical concept combines the dynamic possibilities of beam splitting using a spatial light modulator with the benefits of Bessel beams, which facilitates multi-Bessel beam processing. Beside the simulation and experimental evaluation of the generated multi-Bessel beams, we exemplify the applicability of the developed module for the perforation of thin metal foils by micro drilling.

The Effect of synthesis methods and comparative study of structural properties of micro and nano Ferrites

In this study, Mn(x)Zn(1-x)Fe2O4 ferrite samples with x=0.4 and 0.6 were synthesized using a solid-state method and co-precipitation method. In order to determine the effects of various concentrations (x) on the ferrite's structure, particle size, and crystalline phases, prepared samples were analysed using X-ray diffraction (XRD). The XRD patterns revealed that the synthesized samples display a single-phase cubic spinel structure.FTIR analysis showed for both synthesis method have absorption band in the range 400 to 1000 cm-1.SEM analysis shows extreme homogeneity of all the samples. EDX analysis was used to examine for Mn0.4Zn0.6Fe204,The prepared ferrites powders contain Mn, Zn, and Fe, as shown in both synthesis methods.In this approach, alternative synthesis routes for these ferrites are suggested in this study in order to get around some limitations of the traditional preparation method.

Electrochemical approaches based on micro- and nanomaterials for diagnosing oxidative stress.

This review article comprehensively discusses the various electrochemical approaches for measuring and detecting oxidative stress biomarkers and enzymes, particularly reactive oxygen/nitrogen species, highly reactive chemical molecules, which are the byproducts of normal aerobic metabolism and can oxidize cellular components such asDNA, lipids, and proteins. First, we address the latest research on the electrochemical determination of reactive oxygen species generating enzymes, followed by detection of oxidative stress biomarkers, and final determination of total antioxidant activity (endogenous and exogenous). Most electrochemical sensing platforms exploited the unique properties of micro- and nanomaterials such as carbon nanomaterials, metal or metal oxide nanoparticles (NPs), conductive polymers and metal-nano compounds, which have been mainly used for enhancing the electrocatalytic response of sensors/biosensors. The performance of the electroanalytical devices commonly measured by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in terms of detection limit, sensitivity, and linear range of detection is also discussed. This article provides a comprehensive review of electrode fabrication, characterization and evaluation of their performances, which are assisting to design and manufacture an appropriate electrochemical (bio)sensor for medical and clinical applications. The key points such as accessibility, affordability, rapidity, low cost, and high sensitivity of the electrochemical sensing devices are also highlighted for the diagnosis of oxidative stress. Overall, this review brings a timely discussion on past and current approaches for developing electrochemical sensors and biosensors mainly based on micro and nanomaterials for the diagnosis of oxidative stress.

Editorial for the Special Issue on Corrosion and Etching at Micro/Nanoscale

Micro- and nanoscale corrosion and etching at are important in several fields, from the fabrication of sensors and membranes to investigations of the properties of micro- and nanocomposites [...].

The Effect of Laser Irradiation on The Properties of Micro to Nanolayer Titanium Alloy

In this work, a new technique for Laser irradiation of Ti6Al4VELI was developed, this alloy is an alpha-beta structure, the irradiation was done at room temperature in the normal atmosphere without any external media, the effects of laser irradiation on the Ti6Al4VELI such as the chemical composition of the alloy before and after laser irradiation were recorded by Energy dispersive X-ray &amp;ldquo;EDX&amp;rdquo; technique. the affected zone (thickness) of the laser irradiation technique was limited to the surface in micro to the nanoscale. The variation in mechanical properties due to laser irradiation at different wavelengths was measured by the determination of the variation of modulus and hardness at maximum load with a number of pulses. The wear rate was measured for the Ti6Al4VELI before and after laser irradiation at 5000 pulses where the maximum improvement in the hardness occurs at all wavelengths, in the current study, it improves surface mechanical characteristics. The effect of laser irradiation on the structures was studied by SEM, the quantitative analysis was done at all irradiation conditions. Laser treatment is suitable for both field works and industry. The improvement in mechanical properties occurs due to microstructure changes without significant changes in chemical composition. the efficiency and lifetime of the alloys were increased, the work is registered as patent number 24014 in the Egyptian patent office.

Effect of biobased plasticizers, used as dispersing aids, on mechanical, rheological and thermal properties of micro fibrillated cellulose (MFC)/poly (lactic acid) (PLA) biocomposites over the time: how MFC controls the plasticizer migration?

Effect of biobased plasticizers, used as dispersing aids, on mechanical, rheological and thermal properties of micro fibrillated cellulose (MFC)/poly (lactic acid) (PLA) biocomposites over the time: how MFC controls the plasticizer migration?

Investigation of piezoelectric 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 films in cross section using piezo-response force microscopy

Interest in the piezoelectric and ferroelectric properties of micro- and nanomaterials is increasing due to the advances being made in nanotechnology. However, there are only a few techniques that can detect functional properties at the nanoscale, and one of them is piezo-response force microscopy (PFM). So far, this technique has been mainly used to study surface properties of piezoelectric films. In this investigation, we develop a procedure to study films in the cross section by PFM and to investigate the relaxor-ferroelectric domain structure of pristine, screen-printed, and aerosol-deposited 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 films in the cross section. Due to the different preparation methods used for two films, the grain size and, thus, the relaxor-ferroelectric domain structures differ. Micron-scale domains are observed in the screen-printed films, while sub micrometer-scale domains are found in the aerosol-deposited films. However, no change in the ferroelectric domain structures was observed across the thicknesses of the films.

Recent Progress and Challenges on the Microfluidic Assay of Pathogenic Bacteria Using Biosensor Technology.

Microfluidic technology is one of the new technologies that has been able to take advantage of the specific properties of micro and nanoliters, and by reducing the costs and duration of tests, it has been widely used in research and treatment in biology and medicine. Different materials are often processed into miniaturized chips containing channels and chambers within the microscale range. This review (containing 117 references) demonstrates the significance and application of nanofluidic biosensing of various pathogenic bacteria. The microfluidic application devices integrated with bioreceptors and advanced nanomaterials, including hyperbranched nano-polymers, carbon-based nanomaterials, hydrogels, and noble metal, was also investigated. In the present review, microfluid methods for the sensitive and selective recognition of photogenic bacteria in various biological matrices are surveyed. Further, the advantages and limitations of recognition methods on the performance and efficiency of microfluidic-based biosensing of photogenic bacteria are critically investigated. Finally, the future perspectives, research opportunities, potential, and prospects on the diagnosis of disease related to pathogenic bacteria based on microfluidic analysis of photogenic bacteria are provided.

Spectroscopic studies on Pr3+ doped YPO4 and LuPO4 upon vacuum ultraviolet (VUV) and synchrotron radiation excitation

This work concerns the spectroscopic properties of micro- and nanoscale LuPO4:Pr3+ and microscale YPO4:Pr3+ upon excitation by VUV synchrotron radiation at a wide range of energies (5–45 eV) and two different temperatures (7 and 300 K).Both Pr3+ doped host materials show more intense UV-C emission than other Pr3+ phosphors studied earlier at FinEstBeAMS beamline under the same measurement conditions. The various relaxation processes of 5d14f1 → 4f2 interconfigurational transitions of Pr3+ and the difference between both hosts are discussed in detail.