Prismatic Research Articles

EFFECTS OF ROLLING DEFORMATION ON TEXTURE AND LPSO PHASE OF SPRAY-DEPOSITED MAGNESIUM ALLOYS CONTAINING Nd

Mg alloys have been applied widely as structural materials over the past decades, with low density, high specific strength, stiffness, specific elastic modulus, and high recycling rate. However, their features of poor ductility and formability at room temperature have limited their application due to hexagonal close-packed crystal structure with less independent slip systems. Grain refinement and texture randomization are two means to activate other slip systems. In this work, the billets of Mg-9Al-3Zn-1Mn-6Ca-2Nd alloy produced by spraying deposition method (the Osprey process) were studied in order to analyze the effect of rolling deformation at 350 °C and pass reduction e =20%, 25% and 30% on texture and microstructure evolution of an extruded size-asymmetry Mg alloy by SEM, TEM and XRD. The results show that under the condition of reduction of e =20% at 350 °C, a long-period stacking ordered phase with 24R structure was formed in (Ca, Nd)Al2 phase (C15 Laves phase ). All of basal texture (0002), prismatic texture {1010} , and pyramidal texture {1012} were activated, with pole density level weakened while pass reduction increased (e =20% , 25% and 30% ), namely, texture randomization achieved in Mg alloy, with main causes of nanometer-sized dispersed C15 phase impeding dislocation movement 第938-944页 pp.938-944

Mechanical Properties of Self-Compacted Concrete

In this research, trial mixes were conducted according to Self -Compacted Concrete (SCC) specifications, a mix that gave a higher compressive strength to the age of seven days has been selected. Then after selecting the appropriate mix, concrete samples had poured and were distributed into five groups; each group consists of six cubes, six cylinders, and six prisms. The samples of each group are testing for compressive, tensile splitting, and flexure strengths respectively for the ages of 7, 14, 28, 60, and 90 days respectively. Before of conduction of destructive tests, the samples were t ested using ultrasonic waves to determine the relationship between the concrete strength and pulse velocity and in the same way for all ages in above. Experimental results showed that, all concrete mechanical properties have improved, and the maximum improve was in flexural strength followed by compressive strength and tensile splitting strength. The cube compressive strength increased according to (G1 at 7 days curing) from 34.3% to 71.8%, the percentage of increase of tensile strength according to (G1 at 7 days curing) from 16.8% to 64.3% , modulus of rupture increased according to (G1 at 7 days curing) from 34.6% to 98.7% for ages (14, 28, 60, 90 days) respectively. Pulls velocity increased according to (G1 at 7 days curing): For cube from 5.1% to 23.9%, for cylinder from 21.4% to 40.3%, for prisms from 7.1% to 29.2%.

Non-contact absolute internal distance measurement between two mirrors by using a low-coherence tandem interferometer with optical prism mechanism (1st Report)

Non-contact absolute internal distance measurement between two mirrors by using a low-coherence tandem interferometer with optical prism mechanism (1st Report)

Acoustic dispersive prism

The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

Comparative morphological study of bone regeneration in different rabbit cranial osteotomies: traditional versus new generation osteotomes

The aim of this study was to compare the bone regeneration after skull surgery by means of different recent osteotomy devices, piezosurgery medical (PM) and piezosurgery medical plus (PMP), versus a conventional rotary osteotomy device (OT) in 16 adult white New Zealand rabbits. After 14 days from surgery, the recovery of different resulting bone gaps were observed under structural and TEM-ultrastructural analyses. Our preliminary observations showed that the minimum distance from the osteotomy edge, at which it is possible to observe viable osteocytes in the pre-existent bone, was lower in PMP samples (average 38.2µm) with respect to PM (65.7µm) and OT (83.4µm) ones. Moreover, the size of osteotomy gap performed with OT was about twice in thickness with respect to those obtained by PM and PMP. In relation to our previous investigations (1) on two different types of bone formation occurring in sequence (static and dynamic osteogenesis), we observed in the present study that in PM and PMP samples the osteotomy gap is in a more advanced step of recovery with respect to OT ones: in OT samples numerous cords of stationary osteoblasts, forming preliminary bony trabeculae, were observed in the regenerating newly-formed bone (step of static osteogenesis); whereas, in PM and PMP samples bony trabeculae appeared mostly covered by typical prismatic osteoblasts, arranged in movable laminae (advanced step of dynamic osteogenesis). By histomorphometry, in PM and PMP samples with respect to OT ones: i) values of the regenerated bone area with respect to the total osteotomy area (BV/TV%) are about twice; ii) the number of TRAP positive osteoclasts per linear surface showed a significant increase, suggesting higher bone remodelling. Concerning SEM analysis, in all samples the regenerated bone displays, as expected, higher cell density and less mineralized matrix with respect to the pre-existent bone, independently from the device used. In conclusion, our results indicate that osteotomies performed with PM and PMP can be considered equivalent and show more advanced stages of healing compared to OT, in part due to the lower osteotomy thickness in PM and PMP with respect to OT. This work was supported by grants from MECTRON 2013-15.

Metasurface wave in planar nano-photonics

Development of optical systems is toward smaller sizes, more new functions and improved device performance. However, traditional optical systems face many fundamental limits. For example, the Abbe’s diffraction limit sets a minimal value at which the optical microscopy, telescopy and lithography resolution can be achieved. On the other hand, the Snell’s law states that one can only change the shape or materials of optical elements to realize different optical functionalities. Recently, metasurfaces based on artificially structured thin films with unique optical properties are thought to be a promising alternative to traditional optical materials. The thickness of these structures is far smaller than light wavelength, allowing the miniaturization and integration of several optical components and systems together. But there is still not a universal theory available for the understanding and design of metasurface-based devices. Luo et al. [1] systematically brought forward a new concept of metasurface wave (M-wave), which is quite different from the traditional bulk electromagnetic wave. The M-wave is a special electromagnetic excitation, either propagating along the surface or tunneling through the surface with abrupt phase and amplitude changes, which provides a general theory to describe the principles of ‘‘planar nanophotonics’’. They used the M-wave to extend the traditional laws of diffraction, refraction, reflection and absorption. In particular, they revealed that the M-wave has three unique optical properties: extremely short wavelength, locally tunable phase shift and tunable chromatic dispersion. Based on these three characteristics, several important theories and laws to further elaborate the M-wave theory have been presented, such as the metasurface-assisted diffraction theory (MDT), metasurface-assisted law of refraction and reflection (MLRR), metasurface-assisted law of polarization conversion (MLPC) and metasurface-assisted absorption theory (MAT). These theories would pave the way in the design of novel electromagnetic devices with various improved performance [2–6]. On the basis of the extremely short wavelength property and the MDT which emerged through the M-wave, the authors proposed a plasmonic lithography technique. It was shown that a sub-22 nm resolution can be achieved by using a light source at 365 nm. These results demonstrated that both the Abbe’s diffraction limit and the near-field diffraction limit can be surpassed. Unlike the super-resolved fluorescence microscopy (The Nobel Prize in Chemistry 2014), which only applies well to fluorescence samples, this new technique does not rely on any fluorescent materials and thus has no limitation to applications, in principle. With the locally tunable phase shift property and the MLRR, Luo et al. [1] demonstrated a set of flat optical devices, including lenses, prisms, axicons and spiral phase plates. The author extended the super-resolution ability to far-field imaging systems. It was shown that a 10-m metasurface-based telescope can achieve the performance of a normal 16-m one. This is also a big improvement and contributes to revise the text book of Optics. For instance, Born and Wolf [2] have written in their Principle of Optics that the primary diffraction-limited images of an objective lens would not be observed in more detail by the following eyepiece. On the contrary, the new results show that deep sub-diffraction features absent in the diffraction-limited images of objective lens can be optically restored in the relayed system by taking advantage of the exotic properties M. Hong (&) Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore e-mail: elehmh@nus.edu.sg

Carbon Centered Trigonal Prismatic Tungsten Clusters [W6CCl18](n-) (n=1, 2) containing Copper(I) and Copper(II)

The solid state reaction of WCl6 with copper powder and a reactive source of carbon leads to a new trigonal prismatic carbon-centered tungsten cluster containing copper ions. Cu[W6CCl18] dissolves in organic solvents (dimethylsulfoxide, acetone), resulting in two air stable products Cu(C2H6OS)6[W6CCl18] and Cu(C2H6OS)4[W6CCl18]2. Both of them contain carbon-centered trigonal prismatic tungsten clusters [W6CCl18]n– (n = 1, 2) and Jahn-Teller distorted octahedral copper(II) ions. Crystal structures of all compounds were investigated by single-crystal X-ray diffraction. The presence of carbon as an interstitial atom in the cluster is confirmed by nuclear magnetic resonance spectroscopy.

High-speed phase-shifting interferometry using triangular prism for time-resolved temperature measurement.

This study proposes a high-speed phase-shifting interferometer with an original optical prism. This phase-shifting interferometer consists of a polarizing Mach-Zehnder interferometer, an original optical prism, a high-speed camera, and an image-processing unit for a three-step phase-shifting technique. The key aspect of the application of the phase-shifting technique to high-speed experiments is an original prism, which is designed and developed specifically for a high-speed phase-shifting technique. The arbaa prism splits an incident beam into four output beams with different information. The interferometer was applied for quantitative visualization of transient heat transfer. In order to test the optical system for measuring high-speed phenomena, the temperature during heat conduction was measured around a heated thin tungsten wire (diameter of 5μm) in water. The visualization area is approximately 90 μm×210 μm, and the spatial resolution is 3.5μm at 300,000fps of the maximum temporal resolution with a high-speed camera. The temperature fields around the heated wire were determined by converting phase-shifted data using the inverse Abel transform. Finally, the measured temperature distribution was compared with numerical calculations to validate the proposed system; a good agreement was obtained.

Atomic force microscopy and scanning electron microscopic study on the fluorosis of enamel in rats

To investigate the ultrastructure of enamel in the mandibular incisor tooth in a rat model of dental fluorosis. Thirty 5-week-old male and female rats of SD strain were divided into three groups of ten. The animals in the control group were maintained for 8 weeks on pure deionized water, in the low-fluoride group deionized water with 22.5 mg/L of fluorine (50 mg/L NaF) was used, and in the high-fluoride group deionized water with 45 mg/L of fluorine (100 mg/L NaF) was used. All specimens examined were obtained from the mandibular incisors. Mid-sagittal ground sections were prepared from the direction of incisal point of each incisor for scanning electron microscopy (SEM) and atomic force microscopy (AFM). According to the SEM results, the prisms in the control group had a complete and clear column structure with closely packed enamel rods or enamel prisms. The prisms in the high-fluoride experimental group were collapsed and showed curved and fractured crystallites. The level of prism structural changes in the low-fluoride experimental group was in between that of the control group and the high-fluoride group. AFM for the middle layer enamel showed an average roughness (Ra) of (550.6±32.0) nm in the control group, (415.0±24.2) nm in the low-fluoride group, and (194.3±11.3) nm for the high-fluoride group. There was significant difference between the high-fluoride group and the control group (P<0.05). Formation of rat enamel in the high fluoride environment presented obvious structural collapse and no clearance between prisms. Such changes appear to indicate a loss of normal prism structure in rat enamels from exposure to high levels of fluorine during the maturation period.

Prism adaptation and spatial neglect: the need for dose-finding studies.

Spatial neglect is a devastating disorder in 50–70% of right-brain stroke survivors, who have problems attending to, or making movements towards, left-sided stimuli, and experience a high risk of chronic dependence. Prism adaptation is a promising treatment for neglect that involves brief, daily visuo-motor training sessions while wearing optical prisms. Its benefits extend to functional behaviors such as dressing, with effects lasting 6 months or longer. Because one to two sessions of prism adaptation induce adaptive changes in both spatial-motor behavior (Fortis et al., 2011) and brain function (Saj et al., 2013), it is possible stroke patients may benefit from treatment periods shorter than the standard, intensive protocol of ten sessions over two weeks—a protocol that is impractical for either US inpatient or outpatient rehabilitation. Demonstrating the effectiveness of a lower dose will maximize the availability of neglect treatment. We present preliminary data suggesting that four to six sessions of prism treatment may induce a large treatment effect, maintained three to four weeks post-treatment. We call for a systematic, randomized clinical trial to establish the minimal effective dose suitable for stroke intervention.

Restoring abnormal aftereffects of prismatic adaptation through neuromodulation

Adaptation to optical prisms displacing the visual scene laterally is a widely investigated instance of visuo-motor plasticity, also because prism adaptation (PA) has been extensively used as a treatment for right-brain-damaged patients suffering from left spatial neglect. The lateral visual displacement brought about by prisms, as indexed by a pointing error in the direction of the displacement, is progressively corrected through repeated pointings: after prism removal, a shift in the direction opposite to the prism-induced deviation occurs in visual, proprioceptive, and visuo-proprioceptive straight-ahead tasks (aftereffects, AEs). The cerebellum and the posterior parietal cortex (PPC) are key components of the bilateral cerebral network subserving the AEs, and the reduction of the pointing error during prism exposure in PA. We report the experimental study of a patient with bilateral occipital and left cerebellar damage, who showed a preserved reduction of the pointing errors to rightward displacing prisms, but not the leftward AEs in the proprioceptive straight-ahead task; instead, visual-proprioceptive and visual AEs were preserved. Anodal transcranial Direct Current Stimulation (tDCS) over the left PPC restored the leftward proprioceptive AEs, and anodal tDCS over the left cerebellum abolished the rightward deviation. Conversely, stimulation over the right PPC or the right cerebellum was ineffective. These results provide novel evidence for neuromodulatory effects of tDCS on defective AEs, through the stimulation over dedicated cortical regions.

Interaction between periodic structures of object and X-ray standing wave generated by wavefront-division interferometer.

An x-ray imaging method that utilizes interaction between standing wave and periodic structure of object is proposed. When a periodic object is placed in a standing wave field, the interaction is modulated by relation between the periodic structure of object and the standing wave period. Then, the structure of object can be observed as a modulation of transmission image, and the existence of fine periodic structures can be detected with an imaging detector of low spatial resolution. Feasibility studies have been performed using a standing wave generated by a wavefront-division x-ray interferometer with refractive prism optics.

Structural Analysis of Solar Panel Cleaning Robotic Arm

The efficiency of solar photovoltaic (SPV) panels depends upon the amount of solar irradiance and spectral content. SPV panels are being widely used because of their economic and environmental merits. The performance of SPV panels gets degraded due to factors like air pollution, bird droppings, dust, snow accumulation, etc. An automatic and integrated solar panel cleaning robotic arm (SPCRA) with four-degrees of freedom has been designed to overcome the above factors. The arm has two prismatic and two revolute joints. SPCRA has a unique end effector with a water sprinkler, air blower and a wiper installed as a single unit on it. Few traits like anti-interloped design, automated grid cleaning mechanism, efficient algorithm, all-weather cleaning support, and plug-n-play strategy with optimum costs make it a versatile system for cleaning the SPV panels.

스테레오비전을 이용한 6자유도 머니퓰레이터 변위 측정

In this paper, six-degree-of-freedom (DoF). Displacement measurement technique using a compact stereo-vision system is proposed. The measuring system consists of a camera, an optical prism, two plane mirrors, and a planar marker on a target. The target was attached on an object so that its six-DoF displacement can be calculated using a proposed coordinates estimating algorithm and stereo images of the marker. A prototype was designed and fabricated for performance test. From the test results, it can be confirmed that the proposed measuring technique can be applied to monitoring and control of various manipulators.

Optical Issues in Measuring Strabismus.

Potential errors and complications during examination and treatment of strabismic patients can be reduced by recognition of certain optical issues. This articles reviews basic as well as guiding principles of prism optics and optics of the eye to equip the reader with the necessary know-how to avoid pitfalls that are commonly encountered when using prisms to measure ocular deviations (e.g., during cover testing), and when observing the corneal light reflex to estimate ocular deviations (e.g., during Hirschberg or Krimsky testing in patients who do not allow for cover testing using prisms).

Optimized morphologic evaluation of biostructures by examination in polarized light and differential interference contrast microscopy

Differential interference contrast microscopy (DIC) was possible after the invention of Wollaston prisms that were modified by Nomarski and could duplicate linear polarized light before passing through a specimen (Condenser DIC prism) and to recompose it afterwards (Objective DIC prism), thus creating the phenomenon of interference that depends on the thickness and birefringence of the studied structures. The authors proposed themselves to discuss the performances of this microscope and to widen the area of its usage in the optimized microanatomic analysis of cells and tissues on the native or stained sections. The authors consider it necessary to use DIC microscopy both in forensic medicine (identification of diatoms) as well as in reproduction biology (spermogram) and in early discovery of uterine cervix cancer. K ey Words: DIC microscopy, Wollaston prism, Nomarski prism, polarized light, interference. he progresses achieved in the area of improvement and diversification of optic systems determined the increase of photonic microscopes performances regarding the phase contrast, polarized light and not least, differential interference contrast (DIC) examinations.They assure nowadays the optimization of biostructural assessment due to transformation effects of enlighten electromagnetic waves when passing through optic prism systems, which leads to personalized views. Our aim is to highlight the performances of these microscopes with the purpose of determining their capacity in the optimization of biostructures assessment, in ortology as well as in general and forensics pathology. S tages in the history of practical and theoretical acknowledgement of enlighten electromagnetic waves

First report of Melampsora euphorbiae on Euphorbia hirta L. from Mexico.

During November 2013, a few rust pustules (uredinia) were observed on the lower and upper sides of Euphorbia hirta leaves in Morelia (Michoacan state, Mexico). Uredinia were hypophyllous, golden-yellow, sub-epidermal erumpent and powdery, had a diameter of 0.3 to 0.5 mm and a height of 0.2 to 0.3 mm, and contained smooth- walled paraphyses intermixed with urediniospores. The heads of the paraphyses were clavate-capitate or capitate, 15.5 to 22.5 μm in diameter and had hyaline walls apically thickened up to 4 to 6 μm. Urediniospores were pale-yellow, pedicillate, variously shaped, as they included spherical, ellipsoidal and pyriform forms, measured 15-19x17- 23 μm, and showed hyaline echinulate walls 1.0 to 2.0 μm thick. A small number of subepidermal telial sori forming dark gray crusts were also found on the leaves close to the uredinia. Teliospores were one-celled, prismatic, 13-16×27-48 μm in size, had smooth, light coffee brown walls 1.0 to 1.5 μm thick, apically thickened up to 2 μm. Scanning electron microscopy observations revealed that urediniospores were globoid- or ellipsoid-shaped with fine echinulations. Based on the morphological characteristics and measurements, the rust was identified as Melampsora euphorbiae (Leon-Gallegos and Cummins, 1981). Samples were deposited in the Herbarium of the Faculty of Biology, Universidad Michoacana de San Nicolas de Hidalgo (UMSNH), Morelia, Michoacan, Mexico. To the best of our knowledge, this is the first record of M. euphorbiae on natural populations of E. hirta in Mexico.

Stimulated Raman scattering properties of KDP crystal

In this paper the spontaneous Raman spectrum and stimulated Raman spectrum of potassium dihychogen phosphate (KDP) crystals were compared in detail. In the stimulated Raman spectrum three Stokes lines of the strongest vibration mode, which are 559.43 nm, 589.74 nm, 623.5 nm respectively, were observed. The Stokes lines for other vibration modes didnt appear due to the smaller stimulated Raman scattering (SRS) gain coefficient. In addition, we also compared the gain coefficients of KDP crystal grown by traditional growth method (including annealing and annealing samples) and rapid growth method (including the pyramidal and prismatic sectors samples). The results indicate that the growth method and annealing have no obvious impact on the SRS gain coefficient.

A methodology for applying V–blocks and clamps to non–prismatic workpart fixtures

Most research in computer–aided fixture design (CAFD) aims to develop algorithms to automatically design the fixture configuration of workpieces. Due to the complexity of non–prismatic geometry, the application domain has been mostly limited to prismatic workpiece fixturing. Moreover, based on the 3–2–1 locating principle, the locators employed are mostly restricted to the cylindrical type. This research focuses on another type of fixture configuration for non–prismatic parts that has been mostly overlooked. This is to apply V–blocks in workholding to ensure stable and efficient work setup of non–prismatic parts. The algorithm presented in this paper determines V–block locating by utilising projected geometric reasoning. The major steps of the algorithm include candidate–point generation, angle and distance checking, co–ordinate transformation, and interference analysis. Further more, this paper also explores another algorithm for determining the corresponding clamping location of the V–block. The horizontal clamp is planned based on static principles. To ensure workpiece stability, the planning procedure is classified into three distinct cases according to the force distribution and frictional conditions at the contacting regions. These two algorithms, V–block locating and clamp planning, are applied interactively to obtain the most desired fixture configuration. Finally, an example is provided to explain how these algorithms are applied.

An integrated setup planning and fixture design system for prismatic parts

This paper reports a knowledge–based system for conceptual and layout modular fixture design developed on an intelligent CAD system, ICAD. The integration of setup planning and fixture design is achieved through conceptual fixture design which includes two stages: the pre–setup and post–setup conceptual design. In the pre–setup stage, the system takes feature–based part models as input and generates feasible fixturing features for each possible setup based on static constraints only. This information is then used by a setup planning system developed separately. Post–setup conceptual fixture design takes place when the setup plan is available. For each setup with its intermediate workpiece state, the surface candidates for each fixturing datum are identified and ranked according to various geometric and technological constraints. The best ranked surface for each fixturing datum is selected. The system then performs layout design by generating all the supporting, locating and clamping points for each setup, taking into account various constraints including part geometry, stability, modular fixture elements, and interference. The series of setups are simulated graphically on the computer screen. Output from this system can be used for detailed fixture design. In this paper, the development of the system is described in detail and a case study is presented to highlight its performance.