Formation Of Grooves Research Articles

MODIFICATION OF DIAMOND SURFACE DURING PHOTOLITHOGRAPHY, PLASMA-CHEMICAL CLEANING, AND MAGNETRON DEPOSITION

An influence of the conventional planar technology of the semiconductor surface treatment operations (photolithography, plasma-chemical surface cleaning in radio frequency low-pressure oxygen discharge, and thin metal films growth) on monocrystalline diamond surface topography and roughness is investigated. It is preliminary shown that photolithography without the plasma cleaning and magnetron deposition of an aluminum film do not induce any diamond surface changes which could be found by the optical profilometry, electron and optical microscopy. However, as a result of the lithography some organic contaminants can decrease the adhesion of the aluminum film and have to remove from the surface. Further, the influence of the above-listed surface treatment operations separately and in combinations on the synthetic diamond surface is investigated. It is found that an even short oxygen plasma cleaning during 5 min with a low bias power of 20 W leads to etching the grooves on the diamond surface The depth of the etching grooves varies by more than an order of magnitude in different experiments (0.3 - 19 nm), and by 10-20% within the same substrate under the influence of the poorly controlled external factors. Also, oxygen plasma treatment changes its secondary electron emission coefficient. Deposition of aluminum film after plasma cleaning does not induce noticeable changes in the diamond surface topography. The quality of diamond surface polishing (in “hard” of “soft” direction), the diamond’s type (IIa or IIb) as well as producing method (HPHT or homoepitaxial CVD) do not affect the result of grooves formation.

Experimental Investigation on Machinability of Aluminum Alloy during Dry Micro Cutting Process Using Helical Micro End Mills with Micro Textures.

Aluminum alloy material is widely used in the electronics, weapons, aviation and aerospace industries, due to its medium strength, good corrosion resistance, good toughness and excellent oxidation properties. With the trend of product miniaturization, micro cutting has become the mainstream technique for fabricating micro parts and components, so it is very meaningful and vital to work on removing the cutting fluid from the micro cutting process and make it totally sustainable and eco-friendly. In this work, an attempt has been made to fabricate micro textures onto the rear surface of helical micro end mills with diameters of less than 1 mm. Micro textures in the form of grooves were fabricated using a noncontact low speed wire electrical discharge turning technique. Dry micro cutting experiments were carried out on an aluminum alloy material using helical micro end mills with micro textures and the dry micro cutting surface quality and tool wear have been investigated. The influence of dry micro cutting parameters on the surface roughness parameters were also investigated. Experimental results showed that the Sa and Sq can be reduced to be about 1.56 μm and 2.08 μm, respectively. Contrasting results indicate that the implantation of micro textures does not deteriorate the dry micro cutting surface but improves the machined surface consistency of an aluminum alloy workpiece. The tool wear on helical micro end mills with micro textures involved in the dry micro cutting process of Al 6061 mainly include rear frictional wear, oxidation wear and diffusion wear.

Vimentin Association with Nuclear Grooves in Normal MEF 3T3 Cells.

Vimentin, an intermediate filament protein present in leukocytes, blood vessel endothelial cells, and multiple mesenchymal cells, such as mouse embryonic fibroblasts (MEF 3T3), is crucial for various cellular processes, as well as for maintaining the integrity and durability (stability) of the cell cytoskeleton. Vimentin intermediate filaments (VIFs) adhere tightly to the nucleus and spread to the lamellipodium and tail of the cell, serving as a connector between the nucleus, and the cell’s edges, especially in terms of transferring mechanical signals throughout the cell. How these signals are transmitted exactly remains under investigation. In the presented work, we propose that vimentin is involved in that transition by influencing the shape of the nucleus through the formation of nuclear blebs and grooves, as demonstrated by microscopic observations of healthy MEF (3T3) cells. Grooved, or “coffee beans” nuclei, have, to date, been noticed in several healthy cells; however, these structures are especially frequent in cancer cells—they serve as a significant marker for recognition of multiple cancers. We observed 288 MEF3T3 cells cultured on polyhydroxyoctanoate (PHO), polylactide (PLA), and glass, and we identified grooves, coaligned with vimentin fibers in the nuclei of 47% of cells cultured on PHO, 50% of cells on glass, and 59% of cells growing on PLA. We also observed nuclear blebs and associated their occurrence with the type of substrate used for cell culture. We propose that the higher rate of blebs in the nuclei of cells, cultured on PLA, is related to the microenvironmental features of the substrate, pH in particular.

Morphological, functional and thermal characteristics of hydroxypropylated-crosslinked barley starches

The present study investigated effects of three different levels of crosslinking using a mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) on hydroxypropylated barley starches. Hydroxypropylated barley starches crosslinked with 1%, 1.5% and 2% mixture of STMP and STPP were coded as HPCL(1), HPCL(1.5) and HPCL(2.0), respectively. However, the level of hydroxypropylation employed was same for all the modifications i.e. 6%. The results showed that increase in level of crosslinking increased swelling power, solubility and water holding capacity of starches. HPCL(2.0) starch demonstrated noticeably lower percent transmittance, higher percent retrogradation and elevated peak viscosity. Harder gels were produced by dual modified barley starches. A decline was observed in thermal transition temperatures after dual modification. FTIR was unable to detect much difference among different samples. However, peak at 1414 cm−1 associated with hydroxypropylation was detected. Hydroxypropylation followed by crosslinking led to roughness and grooves formation on the surface of barley starch granules.

Исследование прочности слоистых композиционных материалов с концентраторами напряжений в виде выточек

Исследование прочности слоистых композиционных материалов с концентраторами напряжений в виде выточек

A Study on the Tribological Properties of Al-AlN-Y2W3O12 Hybrid Composites

The effect of the amount of reinforcements, load, sliding distance and sliding speed on the wear properties of aluminum matrix hybrid composites (AMHCs) reinforced with yttrium tungstate (Y2W3O12) and aluminum nitride (AlN) has been investigated. The hardness and wear resistance of the composites improve with the increasing amount of AlN and Y2W3O12. The wear resistance increases with a decrease in the load and an increase in the sliding distance. The AMHCs exhibit the formation of a stable mechanically mixed layer along with fine grooves and oxides under mild conditions (low load, high sliding distance and low sliding speed) resulting in relatively low wear rate and coefficient of friction (COF). However, under severe conditions (high load, low sliding distance and high sliding speed), the formation of larger grooves along with heavy delamination increases the wear rate and COF. Response surface methodology is used to correlate the experimental values with the predicted values. The results show that the load and amount of reinforcement are significantly affecting the wear rate and COF.

Theoretical and experimental analysis of temperature distribution during full tooth groove form grinding

Abstract A calculation model of grinding temperature during full tooth groove form grinding (FTGFG) was established through the simplification of the three-dimensional (3D) heat conduction process and based on the theoretical analysis of the transient moving heat source temperature field. The proposed model calculated the grinding temperature distribution of the gear surface and also described the coupling effect of two adjacent grinding heat sources at the junction of the tooth groove. Based on the grinding principle and the contact geometry relationship between the formed grinding wheel and the workpiece, the distributions of grinding parameters, grinding wheel geometry parameters, the actual contact arc length between the grinding wheel and the workpiece, tangential grinding force, and the heat partition to the workpiece were analyzed. A 3D non-uniform heat flux distribution model was also developed based on the actual tangential grinding force distribution, the linear velocity distribution of the grinding wheel, the heat partition ratio along the cross-section of the tooth groove, and the triangular heat flux model in the direction of the contact arc for the contact zone during FTGFG. Finally, a test method for form grinding temperature measurement was designed, and the theoretical model was verified by experimental results. Test results revealed that the temperature distribution on the tooth groove surface during form grinding was non-uniform. Due to the coupling effect of two adjacent heat sources, the temperature increased sharply, and a steep peak was formed at the flange where the bottom plane and the transition arc intersected or the transition arc and the involute intersected. A comparison between experimental and theoretical results on the ground surface and in the transverse section revealed that the analytical model had better prediction accuracy and that the relative error was within 15 %.

Improvement in friction and wear characteristics using CaF2 as a solid lubricant at different conditions

During machining, adequate cooling and lubrication is much needed to reduce friction, wear, and temperature by efficient heat dissipation resulting in improved surface quality and longer tool life. The various alternative approach developed to provide lubrication and cooling includes minimum quantity lubrication, cryogenic cooling, and machining with the use of solid lubricants. The efficiency of solid lubricant particles greatly depends on the particle size, the wt% of solid lubricant, and base fluid used to prepare a lubricant mixture. Therefore, an attempt has been made in the present investigation, to evaluate the tribological properties of CaF2 with different grain sizes and weight ratios in a base oil. Results demonstrated the anti-wear and friction ability of CaF2 as a solid lubricant by improving the tribological properties of sliding surfaces. An increase in friction coefficient is observed with larger grain size (30 and 50 μm) with 10 and 20 wt% of CaF2 as compared with 10 μm particle size. Results also showed the ability of solid lubricant particles with smaller particle sizes (10 μm) to maintain a thin film of lubrication. As a comparison, CaF2 mixed with a base oil performed equally well compared to MQL under different loading conditions. The reduction in friction coefficient and wear is observed with solid lubricant application due to its excellent lubricity even at higher load and pressure. The analysis shows the presence of wear on disc surface in the form of visible grooves and wear debris in dry and MQL condition whereas lubricating effects of CaF2 is dominant.

Modeling of weld formation in variable groove narrow gap welding by rotating GMAW

Abstract As an effective welding method, rotating arc narrow gap MAG welding must ensure sidewall penetration, which is hard to realize when the groove is irregular in practical production. Therefore, it is significant to construct a weld form modeling for control weld penetration under the variable groove conditions. At first, the welding experiment system and the sensor system were set up. Arc sensing and visual sensing were applied to monitor the welding process, and effective algorithms were developed to extract the weld groove features. Three typical groove forms were considered and sufficient experiments were carried out to obtain enough experimental data. Furthermore, support vector machine is used to model the process. Welding current and the shortest distance between the arc center and the groove sidewall were used to predict the sidewall penetration. The verification results show that the model is effective under the condition that the height change of the groove is not more than 2 mm, the width change is not more than 2 mm, or the inclination angle of the bottom of the groove is not more than 10 degrees. The establishment of this model is very helpful to further control the formation of narrow gap welding.

Electron Energy Loss Spectroscopy of Singular Plasmonic Metasurfaces

AbstractSingular plasmonic metasurfaces, which feature sharp edges or ultra‐small gaps, are characterized by a continuous excitation spectrum that results in broadband light‐harvesting properties. In this paper, an analytical study of the electron energy loss spectroscopy (EELS) of this kind of metasurfaces is presented. Making use of transformation optics, the response of singular metasurfaces is studied when interacting with a moving electron both in the frequency and time domains. This allows gaining a deeper understanding of the surface plasmon compression at the singularities, which is responsible for the broadband spectra, as well as of the effect of blunt singularities and nonlocality in the metal. Two instances of singular metasurfaces are considered: one with sharp singularities in the form of sharp angle grooves, and one with smooth singularities in the form of two nearly touching surfaces.

On the formation and features of the supra-wavelength grooves generated during femtosecond laser surface structuring of silicon

We have investigated the formation process of supra-wavelength quasi-periodic surface structures, commonly termed as grooves, produced during femtosecond laser surface structuring of a silicon target, in air.The experiments have been carried out at two wavelengths, namely 513 nm and 1026 nm, and in multi-pulse irradiation conditions. Both static, i.e., irradiating the same target location, and dynamic, namely scanning the beam along a line, configurations have been explored. We have also carried out simulations of the process by using a multiscale numerical model, based on the two-temperature model coupled to a fluid dynamics approach. The comparison of experimental and numerical results has allowed us to clearly establish the role of hydrothermal waves in the grooves formation process.

Inducing LIPSS on multilayer thin metal films by femtosecond laser beam of different orientations

The occurrence of laser-induced periodic surface structures (LIPSS) has been known for a while. Multilayer thin films, like Al/Ti, are suitable for LIPSS formation and attractive for applications—due to their wearing behavior and corrosion resistance; LIPSS generation may improve their properties as well. LIPSS properties depend not only on the material but also on the beam characteristics, like wavelength, polarization and scanning directions, etc. After exposing with NIR femtosecond pulses from Coherent Mira 900 laser system in several beam exposures, we have analyzed the samples of thin metal film systems with Tescan Mira3 SEM and NTegra AFM. The formation of LIPSS is most probably due to the generation of surface plasmon polariton, through the periodic distribution of energy in the interaction zone which lead to thermal processes in layers and interfaces. Two types of LIPSS were generated, which differ in shape, orientation and in ablation pronounced or not. For consecutive interactions in the same direction, LIPSS maintained its orientation, while for orthogonal passes LIPSS with mutually orthogonal orientation were generated. LIPSS period fluctuated between 320 and 380 nm and structures with pronounced ablation have significantly smaller width. Probable mechanism is that for greater accumulated energy pronounced ablation takes place giving LIPSS in the form of trenches or grooves, while for less accumulated energy the buildup of the material—probably due to pronounced oxidation—lead to LIPSS in the form of hills or ridges.

Micromorphological alterations induced by simulated acid rain on the leaf surface of Joannesia princeps Vell. (Euphorbiaceae)

Acid rain has been detected in natural protected areas of the Atlantic Rainforest in Brazil. We evaluated the effects of simulated acid rain on the leaf blade surface of Joannesia princeps, aiming to assess the species potential as biosensor of acidic precipitation. Seedlings were subjected to simulated rain prepared with pH 4.5 H2SO4-acidulated water and, in the control treatment, pH 6.0 deionized water. Severe microstructural damage was detected in the youngest leaves, consisting in wilting of epidermal common cells, which resulted on alteration of the epidermal relief due to formation of grooves among these wilted cells. Stomatal guard cells were also structurally altered, no longer presenting the turgid aspect which was visible in the control treatment. Epidermal microrelief is characterized by the presence of cuticular striae, which might have been crucial to determine the species susceptibility due to increased roughness and decreased wettability. The implications of this hypothesis are further discussed in light of recent research addressing the responses of native tree species to acid rain. The micromorphological alterations found occurred prior to the onset of visible symptoms, and therefore suggest the use of J. princeps as a biosensor of the impact by acid precipitation.

Effect of symmetrical tilt grain boundary on the compatibility between copper and liquid lithium: Atomistic simulations

Abstract The compatibility between Cu and liquid Li directly affects the safety of fusion devices. In this work, we investigated the compatibility between Cu Ʃ3 (111), Ʃ3 (112) and Ʃ5 (310) symmetrical tilt grain boundaries (STGB) and liquid Li using molecular dynamics (MD) simulation. The Li atoms rapidly penetrate the intergranular area along Ʃ3 (112) and Ʃ5 (310) grain boundaries (GBs), resulting in the formation of liquid grooves at the junctions of GBs and solid-liquid interfaces. However, the Ʃ3 (111) GB shows its resistance to Li penetration. In addition, the interfacial alloying and dissolution of Cu atoms are accelerated by Ʃ5 (310) GB via promoting the escape of Cu atoms. Then we calculated the potential energy distribution of Cu atoms which indicates the liquid metal embrittlement (LME) effect exists between Cu bicrystal and liquid Li. And we demonstrate this embrittlement has a strong correlation with the vacancy formation energy and the segregation energy of Li atoms. Comparing with the experimental results, our simulation results explain the corrosion morphology of polycrystalline Cu in liquid Li, and point out that the LME is the root cause of Cu specimen fragmentation.

Engraving the Surface of Electrospun Microfibers with Nanoscale Grooves Promotes the Outgrowth of Neurites and the Migration of Schwann Cells

AbstractWe report a simple method based upon coaxial electrospinning for the fabrication of aligned microfibers engraved with nanoscale grooves to promote neurite outgrowth and cell migration. The success of this method relies on the immiscibility between poly(ϵ‐caprolactone) (PCL) and poly(vinyl pyrrolidone) (PVP) in 2,2,2‐trifluoroethanol (TFE) for the generation of PVP/TFE pockets on the surface of a PCL jet. The pockets are stretched and elongated along with the jet, eventually resulting in the formation of nanoscale grooves upon the removal of PVP. The presence of nanoscale grooves greatly enhances the outgrowth of neurites from both PC12 cells and chick embryonic dorsal root ganglia (DRG) bodies, as well as the migration of Schwann cells. The enhancements can be maximized by optimizing the dimensions of the grooves for potential use in applications involving neurite extension and wound closure.

Engraving the Surface of Electrospun Microfibers with Nanoscale Grooves Promotes the Outgrowth of Neurites and the Migration of Schwann Cells.

We report a simple method based upon coaxial electrospinning for the fabrication of aligned microfibers engraved with nanoscale grooves to promote neurite outgrowth and cell migration. The success of this method relies on the immiscibility between poly(ϵ-caprolactone) (PCL) and poly(vinyl pyrrolidone) (PVP) in 2,2,2-trifluoroethanol (TFE) for the generation of PVP/TFE pockets on the surface of a PCL jet. The pockets are stretched and elongated along with the jet, eventually resulting in the formation of nanoscale grooves upon the removal of PVP. The presence of nanoscale grooves greatly enhances the outgrowth of neurites from both PC12 cells and chick embryonic dorsal root ganglia (DRG) bodies, as well as the migration of Schwann cells. The enhancements can be maximized by optimizing the dimensions of the grooves for potential use in applications involving neurite extension and wound closure.

Studies on the formation mechanism of incomplete fusion defects in ultra-narrow gap laser wire filling welding

Austenitic stainless steel has many excellent properties and it has been extensively used in rail transit trains. Ultra-narrow gap laser wire filling welding is the preferred welding method to connect austenitic stainless steel. However, with this method, it is easy to form defects such as lack of fusion in the welding process. In order to clarify the mechanism of incomplete fusion defects, this article analyzed incomplete fusion defects from the groove design and the welding wire transfer behavior, integrating with high-speed photography and finite element simulation. It is found that the form of narrow gap groove has a close relationship with the formation of fusible defects. Besides, under the condition of globular transfer, all the complicated recoil force, blocking effect of the large droplet on laser energy, the eruption of metal vapor and turbulence of the molten pool caused by large droplet transfer will cause violent disturbance of the molten pool and seriously affect its heat conduction effect. The base metal incompletely melting, the lack of transfer driving force on the droplet and the failure of droplet wetting and spreading on the sidewalls of the groove are the main causes of welding non-fusion defects. Designing reasonable groove, ensuring the stability of wire feeding, adopting liquid bridge transfer mode and appropriately increasing heat input are conducive to reduce the occurrence of incomplete fusion, which is essential to improve the welding quality and enhance the safety of rail vehicles.

New pest record of emerald stem borer, Agrilus sp. (Coleoptera: Buprestidae) on clove in South Bolaang Mongondow district, North Sulawesi, Indonesia

The attack of emerald stem borer, Agrilus sp. on clove plant was first detected in 2007 by plant census officers at the plantation of P.T. Kawanua Kahuripan Pantera (KKP) in Bolaang Mongondow Selatan District. The surveys of clove pests at the end of 2016 to early 2017 in several clove plantations in South Bolaang Mongondow District, clove trees were found to have died from the attacks of the emerald stem borer. The attack occurred on the young clove tree about 5 to 20-yr-old plant, at a location with a height elevation of about 400 m above sea level (asl) on Lungkap village plantation up to 900 m asl on Tonsili plantation. As a result, the attack can cause the death of clove trees because the larvae bore around the tissue under the bark (cambium, xylem and phloem) so that it interferes with nutrient transport. In clove tree can be found in 1 to 4 larvae. Attack symptoms is in the form of zig-zag grooves. The average attack rate ranged from 17%, 26%, and 25% in each of the plantation resorts observed, namely: Lombuguwon resort, Tapamayondi and Tamonok. Distribution pattern in type fields are clustered with range I values (index of relationship variance and mean) greater than 1 (2,68, 3,03, 2,71); Iδ (Morisita index) greater than 1 (5,88, 3,99, 3,92); and k (negative binomial distribution index) smaller 2 (0,60, 0,49, 0,59). Agrilus sp. is categorized as a new pest in clove plant in Indonesia because it has never been reported before.

Improving the retention capacity of clamping elements

An analysis of the discarded drill pipes that had been used in wedge grips has revealed that the main reason for pipe rejection is the reduction of a pipe wall as a result of plastic deformations, due to damaging the pipe surface by the die teeth. The long-term exposure to loads results in the plastic deformations of cylindrical parts, which could lead to unacceptable damage and distortion of the shape. In the oil industry, when drilling and casing pipes are clamped, stresses over some areas in the capture zone exceed the fluidity limit. Multiple clamps of the pipe could reduce the wall of the pipe in the capture area, which leads to premature failure of the pipe. Pipe crumpling occurs not immediately when the load is applied but gradually, by local plastic deformity of the pipe at various points in length and circumference, where the stresses exceed the limit of the fluidity of the pipe material. In order to prevent unacceptable deformations of pipes during hoisting operations, we have considered the possibilities to reduce loads.In this regard, special attention has been paid to the design of clamping jaws that provide the increased retention capacity and the technology of their manufacture. The greatest retention capacity is ensured by jaws with an oblique intersecting notch. In such jaws, the teeth of the notch are arranged chequerwise. This makes it possible to exclude the formation of vertical grooves on the body of the pipe due to slippage induced by the axial load. However, the manufacture of such notches at the inner cylindrical surface of clamping jaws is associated with some difficulties. This relates to that there are no standard tools for making such notched surfaces of complex configuration. The result of our research is the designed and manufactured special tool, as well as the technology for its fabrication. That has made it easier to cut the notches on clamping jaws that ensure the reliable capture of drill pipes

Archaeometric analysis of two decorated bone pins from Poland reveals Early Bronze Age combination of crafts

This paper presents the conclusions of an archaeometric study on two unique artefacts associated with the Early Bronze Age (EBA) Mierzanowice culture (MC) of south-eastern Poland. Two decorated animal bone pins were found in sepulchral context, each accompanying the skeletal remains of a young woman. Based on previous use-wear analysis, the artefacts are interpreted as clothing pins. Their main characteristic is a geometric decorative pattern in the form of incisions and grooves, filled with a dark, grainy substance. Additionally, one of the pins has a distinct green colouration, which extends over uneroded areas of the surface. An array of imaging and spectrometric techniques was employed to investigate both the inlay and the green staining. While the colouration appears to be post-depositional, the dark substance, identified as fine-grained quartz (possibly raw faience paste) mixed with a black, soot-based pigment (bistre) of adhesive properties, was intentionally applied to the surface of both artefacts. This finding reveals a broad range of skills employed by the craftsperson to manufacture the objects. EBA was a time of emerging specialisation and social stratification, during which local artisans worked within a micro-region producing ‘special’ items that were both functional and socially meaningful.