Microns In Length Research Articles

Mycobacterium Effects of Traits for Microscopy

Research was to study mycobacterium a species of pathogenic bacteria. The research question was impervious to Gram staining resultant of either negative or positive effects. The method involve studies of mycobacterium an etiologic parasite. These were 2 to 4 micrometers in length and 0.2 to 0.5µm in width. The results showed the bacteria settlement in the cytoplasm of the plants and growth. This suggested it can be transferred to other eukaryotes. Plants were immunoprevention treatment 15mL each day for a month. Eukaryotic with possibility of mycobacterium should be considered for treatment at least 15mm of induration or had a Gram-positive result. It concluded the treatment had streptomycin production a synthesis inhibitor. It combined to small 16S rRNA of the 30S subunit prevention of binds of formyl-methinonyl-tRNA to the sequence.

Waveguide-Integrated Light-Emitting Metal–Insulator–Graphene Tunnel Junctions

Ultrafast interfacing of electrical and optical signals at the nanoscale is highly desired for on-chip applications including optical interconnects and data processing devices. Here, we report electrically driven nanoscale optical sources based on metal-insulator-graphene tunnel junctions (MIG-TJs), featuring waveguided output with broadband spectral characteristics. Electrically driven inelastic tunneling in a MIG-TJ, realized by integrating a silver nanowire with graphene, provides broadband excitation of plasmonic modes in the junction with propagation lengths of several micrometers (∼10 times larger than that for metal-insulator-metal junctions), which therefore propagate toward the junction edge with low loss and couple to the nanowire waveguide with an efficiency of ∼70% (∼1000 times higher than that for metal-insulator-metal junctions). Alternatively, lateral coupling of the MIG-TJ to a semiconductor nanowire provides a platform for efficient outcoupling of electrically driven plasmonic signals to low-loss photonic waveguides, showing potential for applications at various integration levels.

Effect of heat treatment and defects on the tensile behavior of a hot work tool steel manufactured by laser powder bed fusion

AbstractMicrostructure and tensile properties of a hot work tool steel manufactured via laser powder bed fusion (LPBF) were investigated. Specimens were built under two different orientations and subjected to two quenching and tempering heat treatments, featuring different austenitizing and tempering temperatures and the eventual presence of a sub‐zero step. Microstructural analyses revealed a homogeneous tempered martensite structure after both heat treatments, with the only distinction of a higher alloying segregation at a sub micrometric scale length in samples subjected to the highest tempering temperatures. Hardness and tensile tests indicated a negligible effect of building orientation on mechanical properties, but a significant influence of heat treatment parameters. The treatment featuring the lower tempering temperatures and the sub‐zero step resulted in higher hardness, tensile strength, and elongation, attributed to a lower martensite tempering and alloying segregation. Tensile fracture occurred via crack initiation and unstable propagation from large LPBF defects in all the investigated conditions.

High-responsivity ultraviolet–visible photodetector based on an individual (GaN)1-x(ZnO)x solid solution nanobelt

(GaN)1-x(ZnO)x solid solution (SS) attracts much attention in the field of photodetectors and photocatalysis due to their excellent photoresponse and adjustable band gap. Although (GaN)1-x(ZnO)x nanoparticles, nanorods and nanosheets have been successfully synthesized, the preparation of one-dimensional (GaN)1-x(ZnO)x SS nanobelts (SSNBs) and their photoresponse performance are rarely reported due to the difficulty of preparation. In this study, single crystal (GaN)1-x(ZnO)x SSNBs with a ZnO content of ∼12.6% are synthesized by a convenient CVD method using liquid Ga as the nucleation site. The prepared NBs are pure (GaN)1-x(ZnO)x SS and not the two-phase compound of ZnO and GaN. More important, the SSNBs with tens of micrometers in length and hundreds of nanometers in width feature the excellent ultraviolet and visible light response. Upon UV illumination (365 nm), the photodetector based on a single (GaN)1-x(ZnO)x SSNB achieves a photoresponse speed of 330 ms and a photoresponsivity of 2.8 × 105 A/W. Under visible illumination (532 nm), the photodetector displays a photoresponse speed of 480 ms and a photoresponse of 1.9 × 104 A/W. This study not only proposes a new method for the synthesis of (GaN)1-x(ZnO)x SSNBs, but also paves the way for the use of (GaN)1-x(ZnO)x SSNBs as building blocks for broad-spectrum responsive photodetectors.

FEATURES OF THE COAT OF YAKS OF THE ALTAI POPULATION

The authors studied the morphometric parameters of yak wool to determine the commodity and technological qualities of the thread of yaks from the Altai population. The research was carried out based on the yak-breeding farm of the Republic of Altai. The study’s objectives included determining the mass fraction of yak wool fractions and the physical properties of down fibres (thinness, length and density of down) of different sex and age groups of yaks of the Altai population. In addition, the authors studied the morphometric parameters of the coat of varying sex and age groups of yaks of the Altai population according to a set of characteristics using methods generally accepted in zootechnics. The weight content of the fractions was determined by analysing wool samples weighing 1 gram taken from different parts of the animal’s body (belly, flank, thigh) for down, awn and transitional hair and entertaining on an analytical balance with an accuracy of 0.0001 g. The length of wool was measured using a metal ruler with an accuracy of 1 mm. The fineness of the thread was determined on a lanometer according to the RIAH method (All-Russian Institute of Animal Husbandry). The authors established differences between the ratios of down, awn and transitional hair in different body parts. Thus, the most significant proportion of soft fibres in yak wool is noted on the side, where its content varies from 68% to 82%. Significantly less fluff is observed on the thigh from 22% to 35% and on the stomach from 11% to 30%. In male yaks, the most down is also found on the side from 67 to 73%, and the least is observed on the thigh (32–42%) and on the stomach (7–15%). In young yaks, the highest down content was noted on the thigh - 82-88%, slightly less on the side - 68-80 and on the stomach - only 24-34%. The thinnest fluff was registered in female yaks - 1.32 microns in length. The authors noticed the best indicators of length wool in male yaks, 5.23 cm. Female yaks are 5.09 cm in fibre length, and young (bulls of young yaks are 4.9 cm compared to adult male yaks. Regarding the mass of downy fibres, the highest arms were in young animals (yaks of young bulls) at - 51.03 mg / cm2 and the lowest at - 49.53 mg/cm2 in male yaks. The down of yaks of the Altai population in thickness corresponds to the 56th grade of sheep wool (semi-thin) and can be used to make high-quality knitwear.

Prediction of drug permeation through microneedled skin by machine learning.

Stratum corneum is the outermost layer of the skin preventing external substances from entering human body. Microneedles (MNs) are sharp protrusions of a few hundred microns in length, which can penetrate the stratum corneum to facilitate drug permeation through skin. To determine the amount of drug delivered through skin, in vitro drug permeation testing is commonly used, but the testing is costly and time-consuming. To address this issue, machine learning methods were employed to predict drug permeation through the skin, circumventing the need of conducting skin permeation experiments. By comparing the experimental data and simulated results, it was found extreme gradient boosting (XGBoost) was the best among the four simulation methods. It was also found that drug loading, permeation time, and MN surface area were critical parameters in the models. In conclusion, machine learning is useful to predict drug permeation profiles for MN-facilitated transdermal drug delivery.

Experimental characterisation of the local mechanical behaviour of cellulose fibres: an in-situ micro-profilometry approach

The accurate mechanical characterisation of fibres of micrometric length is a challenging task, especially in the case of organically-formed fibres that naturally exhibit considerable irregularities along the longitudinal fibre direction. The present paper proposes a novel experimental methodology for the evaluation of the local mechanical behaviour of organically-formed (aged and unaged) and regenerated cellulose fibres, which is based on in-situ micro-tensile testing combined with optical profilometry. In order to accurately determine the cross-sectional area profile of a cellulose fibre specimen, optical profilometry is performed both at the top and bottom surfaces of the fibre. The evolution of the local stress at specific fibre locations is next determined from the force value recorded during the tensile test and the local cross-sectional area. An accurate measurement of the corresponding local strain is obtained by using Global Digital Height Correlation (GDHC), thus resulting in multiple, local stress–strain curves per fibre, from which local tensile strengths, elastic moduli, and strains at fracture can be deduced. Since the variations in the geometrical and material properties within an individual fibre are comparable to those observed across fibres, the proposed methodology is able to attain statistically representative measurement data from just one, or a small number of fibre samples. This makes the experimental methodology very suitable for the mechanical analysis of fibres taken from valuable and historical objects, for which typically a limited number of samples is available. It is further demonstrated that the accuracy of the measurement data obtained by the present, local measuring technique may be significantly higher than for a common, global measuring technique, since possible errors induced by fibre slip at the grip surfaces are avoided.

3D-printed micrometer-scale wireless magnetic cilia with metachronal programmability.

Biological cilia play essential roles in self-propulsion, food capture, and cell transportation by performing coordinated metachronal motions. Experimental studies to emulate the biological cilia metachronal coordination are challenging at the micrometer length scale because of current limitations in fabrication methods and materials. We report on the creation of wirelessly actuated magnetic artificial cilia with biocompatibility and metachronal programmability at the micrometer length scale. Each cilium is fabricated by direct laser printing a silk fibroin hydrogel beam affixed to a hard magnetic FePt Janus microparticle. The 3D-printed cilia show stable actuation performance, high temperature resistance, and high mechanical endurance. Programmable metachronal coordination can be achieved by programming the orientation of the identically magnetized FePt Janus microparticles, which enables the generation of versatile microfluidic patterns. Our platform offers an unprecedented solution to create bioinspired microcilia for programmable microfluidic systems, biomedical engineering, and biocompatible implants.

Unveiling the Intrinsic Structure and Intragrain Defects of Organic-Inorganic Hybrid Perovskites by Ultralow Dose Transmission Electron Microscopy.

Transmission electron microscopy (TEM) is a powerful tool for unveiling the structural, compositional, and electronic properties of organic-inorganic hybrid perovskites (OIHPs) at the atomic to micrometer length scales. However, the structural and compositional instability of OIHPs under electron beam radiation results in misunderstandings of the microscopic structure-property-performance relationship in OIHP devices. Here, ultralow dose TEM is utilized to identify the mechanism of the electron-beam-induced changes in OHIPs and clarify the cumulative electron dose thresholds (critical dose) of different commercially interesting state-of-the-art OIHPs, including methylammonium lead iodide (MAPbI3 ), formamidinium lead iodide (FAPbI3 ), FA0.83 Cs0.17 PbI3 , FA0.15 Cs0.85 PbI3 , and MAPb0.5 Sn0.5 I3 . The critical dose is related to the composition of the OIHPs, with FA0.15 Cs0.85 PbI3 having the highest critical dose of ≈84 e Å-2 and FA0.83 Cs0.17 PbI3 having the lowest critical dose of ≈4.2 e Å-2 . The electron beam irradiation results in the formation of a superstructure with ordered I and FA vacancies along <110>c , as identified from the three major crystal axes in cubic FAPbI3 , <100>c , <110>c , and <111>c . The intragrain planar defects in FAPbI3 are stable, while an obvious modification is observed in FA0.83 Cs0.17 PbI3 under continuous electron beam exposure. This information can serve as a guide for ensuring a reliable understanding of the microstructure of OIHP optoelectronic devices by TEM.

ToF-SIMS Depth Profiling to Measure Nanoparticle and Polymer Diffusion in Polymer Melts

We apply time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and cross-sectioned trilayer samples to separately measure nanoparticle (NP) and polymer diffusion on micrometer length scales in polymer melts. We fabricate polymer/diffusing medium/polymer trilayer samples and measure the cross section to extract the NP or deuterated polymer distribution in 3D using ToF-SIMS. After correcting the data for sample tilt, deconvoluting the beam resolution, and integrating the data to extract 1D concentration profiles, we fit the data to extract the diffusion coefficient. These results from cross-sectional ToF-SIMS are in excellent agreement with earlier studies using well-established ion beam methods. This work establishes ToF-SIMS as a reliable tool for measuring NP and polymer diffusion coefficients and opens the door to investigating diffusion in more complex polymer systems and across longer time and length scales.

Preparation and Characterization of Hydroxyapatite Nanotubes

As the key mineral component of human bones, hydroxyapatite (HA) has grasped much attention due to its outstanding biocompatibility, bioactivity and osteoconductive properties. Among different morphologies of HA materials, the special structure and good performance of HA nanotubes has been the focus of many scientific researchers. HA nanomaterials with hollow tube shapes have a relatively high surface area, low density and good mechanical property. However, the simple and convenient procedure to synthesize well distributed HA nanotubes is still rare. In this article, HA nanotubes with tens of nanometers in diameter and hundreds of microns in length were successfully synthesized via a simple solvothermal route. Calcium oleate and sodium hexametaphosphate are selected as the calcium source and phosphorus source, respectively. The surface structure of the HA nanotubes was observed under a scanning electron microscope. The synthesized HA nanotubes can be used in the area of adsorption, drug delivery and treatment of disease.

Microstructure and evolution of hafnium carbide whiskers via polymer-derived ceramics: A novel formation mechanism

Polymer-derived ultra-high-temperature ceramic (UHTC) nanocomposites have attracted growing attention due to the increasing demands for advanced thermal structure components in aerospace. Herein, hafnium carbide (HfC) whiskers are successfully fabricated in carbon fiber preforms via the polymer-derived ceramic (PDC) method. A novel carbon nanotube (CNT) template growth mechanism combined with the PDC method is proposed in this work, which is different from the conventional vapor–liquid–solid (VLS) mechanism that is commonly used for polymer-derived nanostructured ceramics. The CNTs are synthesized and proved to be the templates for fabricating the HfC whiskers, which are generated by the released low-molecular-weight gas such as CO, CO₂, and CH₄ during the pyrolysis of a Hf-containing precursor. The formed products are composed of inner single crystal HfC whiskers that are measured to be several tens of micrometers in length and 100–200 nm in diameter and outer HfC/HfO₂ particles. Our work not only proposes a new strategy to prepare the HfC whiskers, but also puts forward a new thinking of the efficient utilization of a UHTC polymer precursor.

Possible zoonotic implications of the discovery of the advanced third stage larva of Gnathostoma turgidum (Spirurida: Gnathostomatidae) in a Mexican fish species.

Gnathostomiasis in humans is acquired by consumption of any infected second intermediate host or paratenic host. This includes amphibians, snakes and poultry as well as fish. In this work we report for the first time in Mexico the presence of an AdvL3 of Gnathostoma turgidum in the musculature of a wild fish (Gobiomorus dormitor, which also acts as intermediate host for the larvae of G. binucleatum and G. lamothei), from the Papaloapan River, Veracruz; previously, larvae of G. turgidum had only been recorded in amphibians in Mexico and in wild swamp eels from Tampa, Florida, USA. The larva found is extremely small (approximately 1,500 by 140 microns in length and width, respectively), and was obtained by artificial digestion with pepsin after examining the musculature against the light between two glass plates, a method by which it went unnoticed. Our finding of an AdvL3 in this fish, together with a previous molecular phylogenetic analysis revealing that the five species involved in human infections do not nest in the same clade, suggest that all species in the genus are potentially zoonotic. In this context, we strongly recommend the identification of larvae extracted from human patients at specific level, in order to know the role played by the 3 species distributed in Mexico in human cases of gnathostomiasis.

The load-bearing mechanism of plant wings: A multiscale structural and mechanical analysis of the T. tipu samara.

Spinning winged fruits ("helicopter" samaras) generate significant lift forces at relatively low velocities, which enable the wind to disperse them across long distances. The biological material of the samara sustains the aerodynamic loadings and maintains the physical shape of the samara in the air via a yet unknown load-bearing mechanism. Here, positing that this mechanism fundamentally originates from the macro-to-microscale structural and mechanical characteristics of the samara, we use sub-micron computer tomography, electron microscopy, and multi-scale mechanical experiments to map the structural and mechanical characteristics of the tipu tree (Tipuana tipu) samara down to the micrometer length scale. Then, using theoretical models, we characterize the multiscale structural-mechanical principles of the samara and use these principles to disclose the underlying load-bearing mechanism. We found that the structural motifs of the tipu tree samara are closely analogous to various other types and forms of winged fruits, suggesting that this load-bearing mechanism is widespread in plant wings. The structural-mechanical principles governing the samara bear unconventional design concepts, which pave the way toward the development and engineering of small-scale wing elements for miniature aviation platforms with specialized mechanical capabilities. STATEMENT OF SIGNIFICANCE: The biomaterial of plant wings grants them mechanical resistance to flight forces during wind dispersal. "Helicopter seeds" demonstrate an intricate load-bearing mechanism that spans three structure-functional scales of their biomaterial. This mechanism appears widespread in plant wings and may promote novel micro-engineering design guidelines for futuristic flight materials and small-scale aviation platforms.

Structural Elucidation of a Polypeptoid Chain in a Crystalline Lattice Reveals Key Morphology-Directing Role of the N-Terminus.

The ability to engineer synthetic polymers with the same structural precision as biomacromolecules is crucial to enable the de novo design of robust nanomaterials with biomimetic function. Peptoids, poly(N-substituted) glycines, are a highly controllable bio-inspired polymer family that can assemble into a variety of functional, crystalline nanostructures over a wide range of sequences. Extensive investigation on the molecular packing in these lattices has been reported; however, many key atomic-level details of the molecular structure remain underexplored. Here, we use cryo-TEM 3D reconstruction to directly visualize the conformation of an individual polymer chain within a peptoid nanofiber lattice in real space at 3.6 Å resolution. The backbone in the N-decylglycine hydrophobic core is shown to clearly adopt an extended, all-cis-sigma strand conformation, as previously suggested in many peptoid lattice models. We also show that packing interactions (covalent and noncovalent) at the solvent-exposed N-termini have a dominant impact on the local chain ordering and hence the ability of the chains to pack into well-ordered lattices. Peptoids in pure water form fibers with limited growth in the a direction (<14 molecules in width), whereas in the presence of formamide, they grow to over microns in length in the a direction. This dependence points to the significant role of the chain terminus in determining the long-range order in the packing of peptoid lattices and provides an opportunity to modulate lattice stability and nanoscale morphology by the addition of exogenous small molecules. These findings help resolve a major challenge in the de novo structure-based design of sequence-defined biomimetic nanostructures based on crystalline domains and should accelerate the design of functional nanostructures.

Structural, magnetic and magnetocaloric properties of hexagonal MnCoGe-based thin films

The characteristic size of the magnetocaloric materials in magnetic refrigerators, thermomagnetic regenerators and energy harvesters is usually down to micrometer and nanometer length scales, which provides the largest possible contact surface area to the heat transfer liquid. Therefore, it is pivotal to investigate the structural, magnetic and magnetocaloric properties of magnetocaloric materials at micrometer and nanometer length scales. In the present study, we have successfully fabricated MnCoGe-based thin films using the pulsed laser deposition (PLD) technique. The as-deposited film shows a dense surface, homogeneous chemical distribution and a preferred orientation along the c-axis of the hexagonal Ni2In-type structure. In-situ temperature-dependent X-ray diffraction measurements on the as-deposited films reveal an irreversible structural degradation above 300 °C due to the considerable evaporation of the Mn atoms, which causes the formation of microscale pores in the films. The thermomagnetic behavior of the film annealed at 250 °C displays a reversible second-order ferromagnetic transition of the hexagonal phase at Curie temperature TC = 275 K, and a first-order hexagonal-orthorhombic structural transition below 200 K. The decoupling of the magnetic and structural transitions brings reversible magnetocaloric effect with the entropy change ΔS values of 2.5 J/(kgK) and the refrigeration capacity reaching 89 J/kg in Δμ0H = 5 T, which are comparable to other reported magnetocaloric thin films. Moreover, antiferromagnetic coupling in the low-temperature orthorhombic phase was observed, which has rarely been reported in the MnCoGe-based bulk alloys. The different magnetic ground states between the thin film and the bulk alloys may be originated from the strain effect imposed by the Al2O3 substrate. Consequently, this work not only provides insights into the structural, magnetic and magnetocaloric properties of the MnCoGe-based alloys at a nanometer length scale, but also offers a new idea for tailoring the multifunctional properties for this material family.

Mathematical modeling of microscale biology: Ion pairing, spatially varying permittivity, and Born energy in glycosaminoglycan brushes.

Biological macromolecules including nucleic acids, proteins, and glycosaminoglycans are typically anionic and can span domains of up to hundreds of nanometers and even micron length scales. The structures exist in crowded environments that are dominated by multivalent electrostatic interactions that can be modeled using mean-field continuum approaches that represent underlying molecular nanoscale biophysics. We develop such models for glycosaminoglycan brushes using steady state modified Poisson-Boltzmann models that incorporate important ion-specific (Hofmeister) effects. The results quantify how electroneutrality is attained through ion electrophoresis, spatially-varying permittivity hydration forces, and ion-specific pairing. Brush-salt interfacial profiles of the electrostatic potential as well as bound and unbound ions are characterized for imposed jump conditions across the interface. The models should be applicable to many intrinsically-disordered biophysical environments and are anticipated to provide insight into the design and development of therapeutics and drug-delivery vehicles to improve human health.

Highly Flexible PEDOT Film Assembled with Solution-Processed Nanowires for High-Rate and Long-Life Solid-State Supercapacitors

Self-supporting highly conductive polymers are strongly demanded for high-rate flexible supercapacitors. In this work, we demonstrate that solution-processed poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires with tens of micrometers in length can facilely assemble into highly flexible PEDOT films for high-rate supercapacitors. Our results show that the conductivity of the films (50.8–100 S cm–1) relies on the polymerization time of the nanowires and longer time favors doping of dodecyl sulfate anions but results in a decrease of carrier mobility from 16.08 to 6.05 cm2 V–1 s–1. A specific capacitance of 137 F g–1 along with 98% capacitance retention after 10 000 cycles has been achieved in 1 M H2SO4. Moreover, due to the favorable ion and electron pathways and rapid pseudocapacitive redox reactions, these PEDOT films exhibit nearly thickness-independent capacitive performance even as the film thickness increases up to 100 μm. A solid-state capacitor built with a PEDOT film delivers an energy density of 1.38 mWh cm–3 at 27.9 mW cm–3. Meanwhile, it also exhibits superior long-term electrochemical stability without obvious capacitance decay and excellent structural integrity under various deformation tests. These outstanding properties demonstrate that the PEDOT nanowires could become one of the promising building blocks for developing flexible electrodes with an interconnected network for future high-rate energy storage devices.

Corncob-derived nanocellulose-supported palladium nanoparticles towards catalytic reduction of 4-nitrophenol

This study proposed the efficient extraction of nanocellulose from an agricultural residue and the facile immobilization of metal nanoparticles on the surface of nanocellulose without using any external surfactants. In which, corncob was successively treated by an alkaline aqueous solution, a bleaching agent, and a strong acid in order to achieve nanocellulose, which was subsequently served as a support for palladium nanoparticles (PdNPs/NC). Nanocellulose and PdNPs/NC were thoroughly examined involving Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Such successive chemical treatments of corncob yielded nanocellulose with crystallinity index of over 90 %, and palladium nanoparticles (4.9 % wt. Pd) were successfully immobilized on cellulose nanofibrils (∼50 nm in diameter, micrometers in length). Such a catalytic system (PdNPs/NC) was utilized in the selective reduction of 4-nitrophenol to form 4-aminophenol at room-temperature, complying the pseudo-first-order kinetics (k = 0.1144 min−1), relative to a turnover frequency (TOF) of 1.91 h−1, validating the high reactivity of the newly-generated nanocatalyst.

Interface Microstructure–Based Mechanical Property Evaluation of C-S-H

The grain–grain interface of cement, which is composed of the complex needle-shaped microstructure of calcium silicate hydrate (C-S-H), is crucial in the development of the mechanical properties of cementitious composites. These C-S-H needles grow radially outward from the grain surface. This work proposes a combined experimental and modeling approach to incorporate the finer details of these needle geometries and the distribution of mechanical properties in an interface-based multiscale mechanical model for hydrating tricalcium silicate (C3S). At micrometer and sub-micrometer length scales (<5 μm), electron microscopy images revealed that the geometrical nature of these needles at the grain interface varies with days of hydration. The mechanical properties of C-S-H at the nanoscale were observed to be higher at the inner core and reduced toward the outer product. The model developed can incorporate the details of these needle microstructures and their mechanical properties at the microscale and can predict the bulk properties of hydrated C3S at higher scales.