Hard Tip Research Articles

Writable Cholesteric Liquid Crystal Display and the Algorithm Used to Detect Its Image

Writable cholesteric liquid crystal display (ChLCD) and the algorithm used to detect its image were developed. A hard tip such as the fingertip could be used to draw an image onto the surface of ChLCD. Two states i.e., focal conic state (dark state) as F-state, and planar state (bright state) as P-state were designated in this paper. F-state or P-state could be detected by measuring the capacitance of one pixel of test cell (12 mm times 15 mm/1 times 1). However, it could not be detected using the same method on a 4.1" ChLCD (241 mum times 241 mum/320 times 320) due to the effect of parasitic capacitance. The reason why we measured capacitances and detected F-state or P-state was to look for a method which could be applied to detect the drawn image on ChLCD. By using a writable ChLCD, a user should be able to draw an image on it, and then detect and save the drawn image. Therefore, the high frequency measurement and the algorithm were developed to detect the image on ChLCD. Moreover, color writable ChLCD was also introduced.

Indentation of bone tissue: a short review

IntroductionBone is a highly hierarchical natural composite material,which mechanical properties are investigated from thephysiological elastic behavior up to impact or fatiguedamage accumulation responsible for traumatic or stressfractures. Each hierarchical level of organization contrib-utes to the global mechanical response of a bone structure:– The mineralized collagen fibril (MCF, 200 nm)– The lamella (2–7 μm)– The bone structural unit (BSU, 60 μm)– Bone tissue, cortical shell, or trabeculae (100–3,000 μm)– Trabecular bone (TB, mm)– Organ (cm)Bone matrix quality becomes a central focus in under-standing the etiology of fractures in diseases such asosteoporosis. Macroscopic indentation was adopted in thefirst half of the 20th century to investigate hardness of boneat the tissue level (compact and trabecular) and wasextended to micro- and nano-indentation in the past 10 yearsto evaluate specific mechanical properties of bone structuralunits and single lamellae, respectively. Over this period oftime, more than 375 papers or reviews were published(Scopus, “*indentation and bone,” June 23rd 2008).Consequently, the objective of this paper is to review therecent progress of indentation techniques to evaluate themechanical properties of human bone at these intermediatelevels of organization.Materials and methodsIndentationIndentation consists in pressing a hard tip with a knownforce into a semi-infinite half-space and measuring directlyor indirectly the contact area. In the classical hardness testperformed at the macroscopic or microscopic level, thecontact area is estimated optically from the imprint createdby the tip on the material and leads to the definition ofhardness as the force divided by this area. The mostcommon hardness measuring indenters are sphere (Brinell,Rockwell), four-sided pyramid (Vickers), and asymmetricpyramid (Knoop).Recent depth-sensing technologies allow for measure-ment of the tip displacement during the indentation processof a semi-infinite half-space with micro- and even nano-precision. Indirect estimation of the contact area is obtainedby preliminary calibration of the tip shape and systemcompliance. Shallow indentation depths down to 100 nmallow for spatial resolution of the measurements in themicron range, and the sample position is typically con-trolled by high-precision motorized tables or piezoelectricscanners. Micro- and nano-indentation tips are often madeof diamond and can be found in spherical, conical, andmost commonly, three-sided pyramidal (Berkovich) shapes.The blunted extremity of the tip has a radius of approxi-mately 100 nm. Spherical tips minimize plastic deformationand damage but are difficult to manufacture, flat puncheslead to high stress concentrations, conical tips have an axialsymmetry that remains in the assumption of most theoret-

A new species and two new genera of pinnotherid crabs from the northeastern Pacific Ocean, with a reappraisal of the subfamily Pinnotherinae de Haan, 1833 (Crustacea: Brachyura: Pinnotheridae)

Two monotypic genera, Enigmatheres new genus, and Bonita new genus, are described to receive Fabia canfieldi Rathbun, 1918, and Bonita mexicana new species respectively. Enigmatheres can be distinguished from other Pinnotheridae by the third maxilliped having a gently curved outer margin, with a carpus that is larger than the conical propodus and a dactylus that is inserted on the middle third of the ventral margin of the propodus, walking legs 2 that are asymmetrical in length and the dactyli of walking legs 1, 3 and 4 that are short, slender, conical, slightly curved up to hooked and hard tip. Bonita can be distinguished from other Pinnotheridae by the presence of two sulci on the carapace, protruding anterolateral margins of the carapace, walking leg 3 asymmetrical in length and larger than other walking legs, and walking leg 4 with a clavate propodus. These two new genera and 25 additional ones (nine with hesitation), including Pinnotheres Bosc, 1802 (type genus of Pinnotherinae de Haan, 1833), share a carapace that is soft and thin, walking legs 1-4 that are slender and feeble, antennae with a protuberance on the basal segment and the known zoea larvae being very similar, particularly with an abdomen that widens from somite 1 to 5 and a telson that is laterally convex and posteriorly trilobed. These adult and larval shared features support the monophyly of these genera and clearly diagnose the subfamily Pinnotherinae de Haan, 1833 sensu stricto.

多点荷重を受けるＣＦＲＰ補強パネルの実験的衝撃荷重同定

The present paper discusses an experimental identification method of impact forces acting on CFRP stiffened panels. Especially the present paper develops an impact force identification method under multiple loading. First, a transfer matrix to relate an impact force to sensor responses is determined experimentally by using an impulse hammer test. Next, the location and history of the applied force are identified using measured strain responses. The validity of the present identification method is verified through the experimental results of CFRP stiffened panels for both single and double impact loadings. The effect of impactor tip stiffness on the identification results is also examined using hard and soft tips. It is shown that the impact forces can be identified accurately even for the multiple loading using the experimental transfer matrix obtained by an impulse hammer test with a hard tip.

Pneumatically actuated elastomeric device for nanoscale surface patterning

The authors present a simple polydimethysiloxane (PDMS) device for nanoscale surface patterning by controllably bringing a hard silicon nitride tip on a PDMS membrane in and out of contact with surfaces using pressurized gas to inflate the membrane. The writing process is analogous to contact printing. By regulating the pressured gas to actuate the silicon nitride tip on the PDMS membrane, the nanometer size features can be easily fabricated on substrates. Moreover, using the dot matrix method, this PDMS device can masklessly fabricate arbitrary patterns. In this letter, a nanometer scale three-line pattern is demonstrated.

Manual Application of Controlled Forces to Thoracic and Lumbar Spine With a Device: Rated Comfort for the Receiver's Back and the Applier's Hands

Purpose High volumes of manual therapy work can lead to overuse hand and wrist injuries. This study evaluated hand and back comfort in asymptomatic volunteers during spinal mobilization carried out with an instrumented manual therapy tool. Methods This crossover design study examined 36 asymptomatic physiotherapy students that were tested in pairs. One participant assumed the role of the simulated therapist and the other the simulated patient, before reversing roles. Posteroanterior mobilization conditions formed by using 2 spinal segments (thoracic/lumbar), 2 force application methods (hands/device), and 3 grades of mobilization were applied in a random order. After each combination, both participants in each pair rated hand or back comfort, respectively, on a 100-mm visual analogue scale. Data were analyzed by analysis of variance. Results Rated back comfort was greater for hands than for the device and decreased with greater applied force. When the original hard rubber device tip was changed to one of soft molded rubber, both back and hand comfort improved significantly. Although tool mobilization was still rated as significantly less comfortable than mobilization with hands only, this difference was approximately half the discomfort experienced as the grade of mobilization increased from grade I to grade III. For hand comfort when using the softer device tip, the method of force application was no longer a significant determinant of comfort. Conclusions The mobilizing tool with a molded rubber tip was acceptably comfortable in use with asymptomatic backs and hands. Further research is indicated in manual therapy settings with therapists who have experienced hand pain.

Nanoabrasive wear induced by an AFM diamond tip on stainless steel

With the invention of the atomic force microscope (AFM) it became possible to study the wear phenomena at very small scales, from the micrometric to the atomic range. The AFM tips can be used to simulate a sharp single asperity travelling over a surface and nanowear experiments, at controlled contact pressures and scanning speeds, can be performed in almost any type of material. The same AFM enables to observe and characterize with a high lateral resolution the nano/microworn regions. In the present work, it is presented a preliminary study on the nanoabrasive wear response of a metallic alloy. AISI 316L, an austenitic stainless steel (SS) typically used for biotribological applications, was chosen as case study. A single abrasive asperity travelling on the SS surface was simulated by a hard AFM diamond tip, operating in contact mode. The nanowear tests were carried out with loads between 2 and 20 μN and scanning speeds between 2 and 80 μm/s in areas of 2 μm × 2 μm. It was observed that, under the present conditions, there is a load onset for wear, below what no measurable wear occurs. However, local modifications of the roughness and of the frictional response of the material, that can be detected by AFM techniques, point out that changes in the surface occurs before wear can be quantified. The experimental results also show that the wear rate increases with decreasing scanning speed of the diamond tip. Consequently, the results obtained in this work indicate that, in single submicrometric contact conditions, the abrasive worn volume of the material depends on the load, the number of interactions between the abrasive asperity and abraded surface and on the sliding speed.

True solution of the ploughing friction coefficient with elastic recovery in the case of a conical tip with a blunted spherical extremity

The ploughing friction occurs when a hard tip moves on a surface. The elastic recovery tends to reduce this ploughing part of friction and this is something that has to be taken into account. Models which allow to evaluate the ploughing friction with elastic recovery for perfectly conical tips are based on an approximation. Here we present the true solution of the ploughing friction with elastic recovery for conical tip and conical tip with blunted spherical extremity.

6.3: Writable Cholesteric Liquid Crystal Display and the Algorithm Used to Detect its Image

AbstractWritable Cholesteric Liquid Crystal Display and the algorithm used to detect its image were developed. We could use any hard tip, ex: the tip of a forefinger, to directly write an image on the surface of Cholesteric Liquid Crystal Display (CHLCD). By measuring the capacitance of one pixel of test cell (12mm × 15mm/ 1×1), F‐state or P‐state could be detected. By measuring the capacitance of one pixel of 4.1″ CHLCD (241um × 241um/ 320×320), F‐state or P‐state could not be detected, due to the effect of parasitic capacitance. Therefore, high frequency measurement and the algorithm were developed to detect the image on CHLCD.

Peak effect versus skating in high-temperature nanofriction

The physics of sliding nanofriction at high temperature near the substrate melting point, TM, is so far unexplored. We conducted simulations of hard tips sliding on a prototype non-melting surface, NaCl(100), revealing two distinct and opposite phenomena for ploughing and for grazing friction in this regime. We found a frictional drop close to TM for deep ploughing and wear, but on the contrary a frictional rise for grazing, wearless sliding. For both phenomena, we obtain a fresh microscopic understanding, relating the former to 'skating' through a local liquid cloud, and the latter to linear response properties of the free substrate surface. We argue that both phenomena occur more generally on surfaces other than NaCl and should be pursued experimentally. Most metals, in particular those possessing one or more close-packed non-melting surfaces, such as Pb, Al or Au(111), are likely to behave similarly.

Physics and nanofriction of alkali halide solid surfaces at the melting point

Alkali halide (1 0 0) surfaces are anomalously poorly wetted by their own melt at the triple point. We carried out simulations for NaCl(1 0 0) within a simple (BMHFT) model potential. Calculations of the solid–vapor, solid–liquid and liquid–vapor free energies showed that solid NaCl(1 0 0) is a nonmelting surface, and that the incomplete wetting can be traced to the conspiracy of three factors: surface anharmonicities stabilizing the solid surface; a large density jump causing bad liquid–solid adhesion; incipient NaCl molecular correlations destabilizing the liquid surface, reducing in particular its entropy much below that of solid NaCl(1 0 0). Presently, we are making use of the nonmelting properties of this surface to conduct case study simulations of hard tips sliding on a hot stable crystal surface. Preliminary results reveal novel phenomena whose applicability is likely of greater generality.

MODELING AND ANALYSIS OF NANOTIPS FOR THERMOELECTRIC COOLERS

Thermoelectric cooling system can be used in many applications. The properties of structured point contact at the cold end affect the performance of thermoelectric cooling. The performance of metal point junctions as a function of tip radius show that the smaller the tip radius, the better the figure of merit. This paper presents the modeling and analysis of the nanotips. Each nanotip will have to carry some fraction of the weight of the thermoelectric material and the silicon slabs. The small apical area of each nanotip causes a very high pressure build up. The device may be loaded externally to ensure proper nanotip and thermoelectric material contact. A deformation of approximately 10 to 15 nm would be ideal. Finite Element Analysis (FEA) needed to be applied to determine how tall each nanotip must be to maximize soft and hard tip contacts. FEA was also needed to approximate the amount of external loading that will be necessary. ANSYS software was used in the modeling and analysis of the nanotips.

Comparison of Anesthesia Associated (AA) Sedation with Conscious Sedation (CS) in Successful Completion of Endoscopic Retrograde Cholangiopancreatography (ERCP)

Mortality From EUS Jesse Lachter Introduction: EUS is widely perceived to be, as reported, a very safe procedure. Early statistics, from pooled data, found a one in 37,915 risk of mortality. New instruments, linear EUS, and FNA and other invasive techniques, justify reevaluation of data on complications. Accumulating data on complications suggests major revision of the mortality statistics. Patients and Methods: Following initiation of a national survey of EUS utilization, a repository of information on complications developed. Creation and utilization of this data base led to continuous describing of complications. The higher than expected frequency of such complications, especially of mortalities, led to investigations of each case. Results: Seven local cases, and five cases from outside of Israel, of EUS-caused deaths were found. This series represents more cases than that cumulatively described as case reports in all of the relevant literature of the past 24 years, since the introduction of EUS. In the cases analyzed, FNA was not involved in any procedure. The Pentax instruments with their longer hard tip than the Olympus linear instruments, were involved in six of the seven mortalities; no cases involved Fuji scopes. Notably, only one of the 20 EUS centers in Israel uses a Fuji system. Duodenal tears, leading to retroperitoneal perforations, were the cause of 10 of the 12 deaths. The other two deaths were (one each) from esophageal perforation, and from aspiration. One case occurred from a procedure performed as part of a live demonstration of EUS. At least five cases involved patients with duodenal diverticuli. These diverticuli may have had a role in the cause of doing the EUS, in procedures which were initiated to search for suspected CBD stones. Delay in diagnosis of perforation was common. five of the seven Israeli deaths from EUS occurred during the first year and/or 150 first procedures of the endosonographer. Conclusions: EUS has significantly higher risks than previously thought. The Israeli mortality rate from EUS, averaging about one death from each 2500 procedures, was found to be over 15 times that in the published (somewhat dated) literature. To minimize the risks of death from EUS, this study suggests 1appropriately long traineeships, 2attention to duodenal diverticuli, 3a high index of suspicion of retroperitoneal tears with knowledge of their management, 4and appreciation of the EUS instrument designs.

Fast-opening, high-throughput gas valve and application for inertial fusion energy R&D

A fast-opening, high-throughput gas valve and its application to inertial fusion energy (IFE) research and development are described. The valve is a pilot type with two stages of active components. The pilot or first stage section is magnetically driven and equipped with a 4.2-mm-diam orifice. The pilot valve is energized to initiate operations and dumps gas from the upstream section of the second stage to the main valve outlet, and the resultant pressure differential across the large (22.3-mm-diam) output orifice seat causes mechanical activation of the second stage. Both stages are equipped with hard polyimide stem tips and springs for sealing. The valve has been operated reliably with helium gas at pressures in the range of 4–35 bar and frequencies up to 6 Hz, with maximum flow rates of ≈106 Torr l/s. The valve was developed to provide helium propellant gas for accelerating IFE targets to speeds up to 400 m/s in an experimental injector system under construction by General Atomics.

AFM ANALYSIS OF QUANTUM DOT STRUCTURES INDUCED BY ION SPUTTERING WITH DIFFERENT TIPS

With tips of different hardness, we analyzed the effect of the hardness and shape of the actual AFM tip on the measurement of the best GaSb quantum dot (QD) structures induced by low energy Ar + sputtering. The comparison indicated that the complete information on the detailed dot shape and order structure can be determined with the hard and good tip, while with the soft or worn tip some information on the dot height and shape cannot be obtained. Our results suggest that, in order to obtain the complete surface information, the high hardness and good AFM tip should be used for semiconductor QD structures.

Magnetic force images of nanomagnetic domains taken with platinum-coated tips

This article deals with magnetic force microscope images of nanosized domains in Co-coated films made by Pt-coated tips as well as micromagnetic images of data tracks written in recording media. Pt-coated tips have improved image delineation of the magnetic field distribution compared to images obtained by Co-coated hard magnetic tips. The force acting on Pt-coated tips in the magnetic field of the substrate was modeled assuming a paramagnetic tip. Due to the ferromagnetic nature of the interaction between the tip and substrate the spatial resolution of hard magnetic tips was shown to be inadequate to measure details of the features of nanosized domains. A comparison of the magnetic images made by Pt-coated tips with topographic images shows that magnetic domains resist thermal erasure at ambient temperature when they are formed of eight metallic grains.

Micro-scratch evaluation of rock types—a means to comprehend rock drill wear

Drilling, transportation and handling of rock always result in wear of the equipment that comes into contact with the rock and rock fragments. Rock is normally considered rather hard, and the contact leads to abrasion, erosion and point fatigue. However, the wear mechanisms of the tools are often complex and vary in character depending on the rock type. To understand the wear mechanisms of the cemented carbide used in rock drill bits, it is central to understand how different rock types respond to severe scratching from hard tips. A cemented carbide tip with radius 10 μm was used in a scratch tester at progressive loads of 0 to 20 N and at constant loads of 10 N. The tested rock types were calcite, two types of magnetite, hematite, leptite, mica schist, granite, sandstone and quartz spanning average hardness values from 190 up to 1220 HV. The scratches were investigated in SEM and the friction coefficient between rock and the tip was measured. In addition, the wear volume of the cemented carbide tip is measured. The rock types differed significantly with respect to damage mechanism and critical load for transition from a mild to a more severe damage. The friction behaviour correspondingly shifted from rather smooth to very fluctuant. The wear of the tip was found to be correlated to the hardness of the rocks, but was also influenced by the grain size, the quartz content and isotropy. The implications from the present results on full-scale rock drill wear are discussed.

If I tell you I love you

If I tell you I love you

Molecular dynamics simulation of high-speed nanoindentation

A series of molecular dynamics simulations has been performed to studyhigh-speed nanoindentation of a hard pyramidal tip into Al substrates.The effects of several process variables are investigated, includingsystem temperature, tip-substrate bonding, indentation force, andsurface orientation. We discuss the results and the deformationmechanisms that occur during indentation.

Micromagnetic structure images taken using platinum coated tips

We report on magnetic force microscopy images of data tracks written in recording media taken using Pt-coated tips. The force acting on the tip when immersed in the magnetic field of the substrate was modeled assuming diamagnetic and paramagnetic interactions. The sample scanning using Pt-coated tips shows an improvement in the image delineation of the magnetic field distribution compared to the images taken using Co-coated hard magnetic tips and the display of at least a twice higher data track density.