A CAD/CAM system for precision cams with three CNC interpolation methods

Design and manufacture of cams are complicated engineering tasks usually performed independently of each other. Therefore, a CAD/CAM system for cams would be very useful. The mathematical cam profile must be interpolated at some increment to create the numerical data for CNC machining. The interpolation method has significant effects on the dynamic performance. The focus of this paper is to develop a methodology of computer-aided design and manufacturing for precision cams by consideration of three CNC interpolation methods: linear, circular and R-. Various aspects of the features of the interpolation method are explained and compared. The presented software can simulate a roughing and finishing sequence on a given cam blank. The computerised procedure is detailed with accompanying examples.Nomenclature D_p(h) Jacobian matrix of family at pointp - ⁿ n-dimensional Euclid space - curvature - pressure angle - e offset - h _f family of follower - L step length - s displacement of the follower - first derivative of the displacement with respect to cam angle     

Boolean random functions

A Boolean function f in Rⁿ is the supremum of upper semi-continuous random functions f'i which are almost surely positive, bounded with compact support and centred at the Poisson points (i). They generalize to functions of classical Boolean model for sets. The Boolean function f may be studied via its subgraph, i.e. as a random set in Rⁿ x R. The key notion is then the functional Q(Bt), i.e. the probability that a compact set Bt centred at altitude t misses the subgraph of f. The general expression of Q(Bt) is given, and followed by a series of important derivations (volumes, gradients, numbers of summits, etc). Theorems of structure are given: they concern the properties of infinite divisibility for the sup, and domains of attraction for Boolean functions. The last sections are devoted to the study of two particular Boolean functions; emphasis is put on the stereological implications of the approach. A critical example illustrates the theory.     

A full factorial investigation of the erosion durability of automotive clearcoats

A full factorial experimental investigation has been carried out into factors affecting the resistance of a commercial acrylic/melamine automotive clearcoat to erosion by silica sand particles. The factor variables and their ranges were: particle size 125–425 μm; temperature 30°C–65°C; impact angle 30°–90°; particle velocity 35 m s⁻¹–55 m s⁻¹; and the baking process applied to the coating. An empirical linear regression model for the erosion response of the coating with R²_adj=97.5% was generated from the data. The regression coefficients of this model quantify the relative strengths of the effects of each of the factors. Several interactions between the factor variables were identified. In particular, the glass transition of the coating, which occurs at 40°C, has a significant effect on its response to erosion. The study has allowed the combinations of conditions that would be of most concern for automotive paint users to be identified.     

Centrifuge polarizing microscope. I. Rationale, design and instrument performance

We first describe early uses of the centrifuge for deciphering physical properties and molecular organization within living cells, as well as the development and use of centrifuge microscopes for such studies. The rationale for developing a centrifuge microscope that allows high‐extinction polarized light microscopy to observe dynamic fine structures in living cells is next discussed. We then describe a centrifuge polarizing microscope (CPM) that we developed for observing fine structural changes in living cells which are being exposed to up to ≈ 11 500 times earth's gravitational field (g). With the specimen housed in a rotor supported on an air spindle motor, and imaged through an external microscope illuminated by a precisely synchronized flash of less than 10 ns duration from a Nd:YAG laser, the image of the spinning object remains steady up to the maximum speed of 11 700 rev min^?1, or up to ≈ 11 500 × g. The image is captured, at up to 25 frames s^?1, by an interference‐fringe‐free CCD camera that is synchronized to the centrifuge rotor. At all speeds (in 100 rev min^?1 increments), the image is resolved to better than 1 µm, while birefringence of the specimen, housed in a specially designed specimen chamber that suffers low‐stress birefringence and prevents leakage of the physiological solutions, is detected with a retardance sensitivity of better than 1 nm. Differential interference contrast and fluorescence images (532 nm excitation) of the spinning specimen can also be generated with the CPM. The second part of this study (Inouéet al., J. Microsc. 201 (2001) 357–367, describes several biological applications of the CPM that we have explored. Individual live cells, such as oocytes and blood cells, are supported on a sucrose or Percoll density gradient while other cells, such as cultured fibroblasts and Dictyostelium amoebae, are observed crawling on glass surfaces. Observations of these cells exposed to the high G fields (centripetal acceleration/g) in the CPM are yielding many new results that lead to intriguing questions regarding the organization and function of fine structures in living cells and related quasi‐fluid systems.     

Uncertainty in ultrasonic thickness measurements based on the spacing between the first and second bottom-reflected signals. II. Rough bottom surface. Irregularities with rectangular profiles

The uncertainty in ultrasonic thickness measurements as a function of the depthR _m.b of a rough layer on the bottom surface of a tested object based on measurements of the separation between the first and second bottom-reflected pulses (more briefly,h ₁₂-method)¹ has been investigated. The simplest model of the rough layer, i.e., a layer with rectangular profiles of juts, has been analyzed. The function Δh ₁₂(R _m.b ) has been obtained theoretically and tested in experiments. Theh ₁₂-method of thickness measurement has been compared with theh ₁-method for objects with rough surfaces. As in the case of theh ₁-method, a critical range ofR _m.b has been discovered, where the measurements by ultrasonic thickness gauges are unstable, the amplitudes of the first and second bottom-reflected signals are minimal, the uncertainty Δh ₁₂ has the maximal absolute value, has a jump, and changes its sign. The width of this critical range is less than in the case of the input surface. The theoretical conclusions are supported by experimental data.     

Fluorescence relaxation in 3D from diffraction-limited sources of PAGFP or sinks of EGFP created by multiphoton photoconversion

The relaxation of fluorescence from diffraction‐limited sources of photoactivatable green fluorescent protein (PAGFP) or sinks of photobleached enhanced GFP (EGFP) created by multiphoton photo‐conversion was measured in solutions of varied viscosity (η), and in live, spherical Chinese hamster ovary (CHO) cells. Fluorescence relaxation was monitored with the probing laser fixed, or rapidly scanning along a line bisected by the photoconversion site. Novel solutions to several problems that hamper the study of PAGFP diffusion after multiphoton photoconversion are presented. A theoretical model of 3D diffusion in a sphere from a source in the shape of the measured multiphoton point‐spread function was applied to the fluorescence data to estimate the apparent diffusion coefficient, D_ap. The model incorporates two novel features that make it of broad utility. First, the model includes the no‐flux boundary condition imposed by cell plasma membranes, allowing assessment of potential impact of this boundary on estimates of D_ap. Second, the model uses an inhomogeneous source term that, for the first time, allows analysis of diffusion from sources produced by multiphoton photoconversion pulses of varying duration. For diffusion in aqueous solution, indistinguishable linear relationships between D_ap and η⁻¹ were obtained for the two proteins: for PAGFP, D_aq= 89 ± 2.4 μm² s⁻¹ (mean ± 95% confidence interval), and for EGFP D_aq= 91 ± 1.8 μm² s⁻¹. In CHO cells, the application of the model yielded D_ap= 20 ± 3 μm² s⁻¹ (PAGFP) and 19 ± 2 μm² s⁻¹ (EGFP). Furthermore, the model quantitatively predicted the decline in baseline fluorescence that accompanied repeated photobleaching cycles in CHO cells expressing EGFP, supporting the hypothesis of fluorophore depletion as an alternative to the oft invoked ‘bound fraction’ explanation of the deviation of the terminal fluorescence recovery from its pre‐bleach baseline level. Nonetheless for their identical diffusive properties, advantages of PAGFP over EGFP were found, including an intrinsically higher signal/noise ratio with 488‐nm excitation, and the requirement for ∼1/200th the cumulative light energy to produce data of comparable signal/noise.     

Quantitative studies on the preservation of choline and ethanolamine phosphatides during tissue preparation for electron microscopy. I. Glutaraldehyde, osmium tetroxide, Araldite methods

The loss of ¹⁴C ethanolamine- and ³H choline-labelled phospholipids from rat liver during tissue preparation for electron microscopy has been examined. Column and thin-layer chromatography combined with double-label scintillation spectrometry were used to analyse the radioactive phospholipid content of the livers of rats injected simultaneously with ¹⁴C aminoethanol and ³H choline chloride. After 4 h (in vivo) the ¹⁴C and ³H labels were mainly incorporated into phosphatidyl ethanolamine and phosphatidyl choline respectively but some ¹⁴C label had been incorporated into phosphatidyl choline. Chopped rat liver was fixed in glutaraldehyde or osmium tetroxide or both sequentially and tissues were dehydrated in ethanol and embedded in Araldite. In each procedure examined the choline label proved more labile than the ethanolamine. After glutaraldehyde fixation alone complete loss of phosphatidyl choline occurred and half of the phosphatidyl ethanolamine was also lost. Following osmium tetroxide fixation negligible loss of either phosphatide occurred. In terms of phospholipid retention, no advantage was gained by glutaraldehyde fixation prior to osmium tetroxide fixation. The results show that both ethanols and embedding monomers are potent phospholipid solvents. The data also suggests that EM autoradiography of these two phosphatides may be carried out with reasonable confidence although it must be pointed out that a high degree of retention does not necessarily imply retention in situ.     

Image-based determination of chord lengths in air-dried lungs

An image-based method was developed in order to determine chord lengths in sections of dog and sheep lungs air-dried at 25 cm H₂O transpulmonary pressure. To facilitate image processing, optical contrast in the sections was optimized with respect to section thickness, stain type, stain concentration, staining temperature, staining time and clearing method. Digital processing of images used standard procedures, e.g. thresholding, dilation and thinning, as well as algorithms written to subtract background, delete spots and measure chord lengths. Correlation of image-based vs. manual determination of mean chord length in 17 sections from a sheep lung, stained for optimal contrast yielded an R² of 0.82 (P < 0.0001). For 95 sections from three dog lungs, stained with lower contrast, R² was 0.65 (P < 0.0001). Weaker correlations were observed between image-based and manual determinations of the standard deviation, the geometric standard deviation, and the 95th percentile of chord lengths (P < 0.05). The results show that image-based stereology of inflated air-dried lungs can provide valid measures of mean chord length and other statistics of chord length distribution.     

Microscopic and phytochemical techniques as a tool for authentication of herbal drug chiraita: Swertia cordata (G. Don) C.B. Clarke

Swertia cordata (G. Don) C.B. Clarke is one of the potential medicinal plants extensively used in eastern traditional medicine such as Unani, Ayurveda, Siddha, and in traditional Tibetan and Chinese medicine. S. paniculata is the common adulterant of S. cordata at herbal shops and markets but S. paniculata is also used in number of herbal formulations. The present study was conducted to use microscopic, pharmacognostic, and phytochemical techniques as a tool for the authentication of herbal drug chiraita (S. cordata). In herbal markets, mixing, adulteration, and use of spurious materials as substitute have become a major concern for herbal practitioners, local user, and industry for reasons of safety and efficacy. Therefore, authentication of medicinal plants is of utmost importance at each level of drug research. In the present study, anatomical features of two species showed a great diversity, as irregular epidermal cells and nonglandular, unicellular trichomes were found in S. cordata while in S. paniculata epidermal cells were hexagonal in shape and trichomes were A‐shaped. Antioxidant activity of two species showed a great variation where IC₅₀ value recorded for S. cordata was 208 μg/mL, while for S. paniculata IC₅₀ was 624 μg/mL. The study can serve as an important source of information to achieve the authenticity and to evaluate the quality and purity of the plant material in accordance to WHO guidelines. As this species is greatly exploited, so conservation is highly recommended.     

Brief Note : Micropropagation of <i>Glandularia perakii</i> Cov. et Schn. (Verbenaceae), a native species with ornamental potential

Glandularia perakii is a perennial species with beautiful violet flowers that grows in the stony soil of Mendocine pedemont. A plentiful and prolonged flowering confers it an important ornamental potential. In this paper, a method of propagation of G. perakii from nodal segments is reported. Proliferating microshoot cultures were obtained by placing nodal segment on Murashige and Skoog medium (MS) supplemented with 20 g.L^-1 of sucrose without growth regulators. In this medium multiplication rate after 20 days was 7.9. Rooted plants were acclimatized successfully .     

Shear force near-field optical microscope based on Q-controlled bimorph sensor for biological imaging in liquid

Shear force near‐field microscopy on biological samples in their physiological environment loses considerable sensitivity and resolution as a result of liquid viscous damping. Using a bimorph‐based cantilever sensor incorporating force feedback, as recently developed by us, gives an alternative force detection scheme for biological imaging in liquid. The dynamics and sensitivity of this sensor were theoretically and experimentally discussed. Driving the bimorph cantilever close to its resonance frequency with appropriate force feedback allows us to obtain a quality factor (Q‐factor) of up to 10³ in water, without changing its intrinsic resonance frequency and spring constant. Thus, the force detection sensitivity is improved. Shear force imaging on mouse brain sections and human skin tissues in liquid with an enhanced Q‐factor of 410 have shown a high sensitivity and stability. A resolution of about 50 nm has been obtained. The experimental results suggest that the system is reliable and particularly suitable for biological cell imaging in a liquid environment.     

双压电薄膜管道微机器人的功耗分析及电路优化设计

研究了PZT双压电薄膜管道微机器人的功率消耗,推导出其功耗计算公式S=Kfcv²,指出微机器人功耗与驱动电压幅值平方成正比,与驱动电压的频率成正比,与微机器人的电容成正比.优化设计了微机器人的驱动电路,使得其在驱动电压幅值不变的情况下,大幅度提高运动速度.通过实验验证此结论.以上分析研究是此类微机器人无缆化设计的理论基础.     

An automatic system for controlling the UV-radiation dose

A photodetector based on an ⁺-GaAs/n-ClInPc heterojunction, photosensitive in the 200- to 1000-nm wavelength range, is described. The ClInPc absorbtance is high:K _λ=2×10⁷ m⁻¹ for λ=220 and 380 nm. The photosensitivity of the photodetector is 2250 V/W (S=1 cm²). An automatic system for controlling the UV-radiation dose was developed on the basis of this photoreceiver.     

An X-ray microanalytical examination of precipitation methods for the ultrastructural localization of potassium in plant tissue: I. Cobaltinitrite

In vitro and in vivo studies were carried out to assess the feasibility of adapting the cobaltinitrite method for the ultrastructural localization of K⁺ in plant cells. The relatively low mobility of the cobaltinitrite ion and the solubility of the precipitation product resulted in the formation of only a few large deposits in each cell. The addition of Ag⁺ at the time of precipitation was found to increase the number of small deposits retained in sections. However, cobaltinitrite reagents frequently caused plasmolysis and poor cytoplasmic preservation. Precipitation during freeze-substitution was also attempted. It was concluded that precipitation of K⁺ using cobaltinitrite has only limited use in low magnification electron microscopy in conjunction with light microscopy.     

Machinability study on composite (polyetheretherketone reinforced with 30% glass fibre–PEEK GF 30) using polycrystalline diamond (PCD) and cemented carbide (K20) tools

Polyetheretherketone (PEEK) is a relatively new technical thermoplastic material, which has excellent physical properties. By this reason exits a strong need to understand the issues associated with the machining of this thermoplastic. The major concern of this paper is the study of the cutting parameters (cutting velocity and feed rate) under power (Pc), specific cutting pressure (Ks), surface roughness (Ra) and International dimensional precision (IT) in PEEK reinforced with 30% of glass fibre (PEEK GF30). A plan of experiments, based on the methodology of Taguchi, was established considering turning with prefixed cutting parameters in the PEEK GF30 workpiece. The analysis of variance (ANOVA) was preformed to investigate the cutting characteristics of PEEK GF30 using a polycrystalline diamond (PCD) and a cemented carbide (K20) cutting tool.     

Studying Field Dependence of Reversible Magnetic Permeability in Plastically Deformed Low-Carbon Steels

The field dependences of the signal U^~ (Н) across the measuring winding of an induction transducer, which are proportional to reversible magnetic permeability, have been measured in lowcarbon St3 steel plastically deformed by stretching under reversal of its magnetization along the major hysteresis loop both when unloaded and under an elastic tensile load. A method is proposed for isolating the contribution rendered to the measured signal by the irreversible displacement of only 90-degree domain walls. The method consists in subtracting the curve U^~ (Н) measured under the elastic tensile load of a magnitude sufficient to compensate for internal compressive residual stresses in the sample from the no-load U^~ (Н) curve. It has been established that the induced magnetic anisotropy field obtained with this method is virtually no different from that produced by the method in which no-load U^~ (Н) curves are approximated.

     

The complex buckling of flexible sheet materials—Part II. Experimental study of three-fold buckling

This paper reviews the technological importance of the problems of complex buckling of textile fabrics and other sheet materials and the reasons why conventional shell theory is of little value. It stresses the importance of the occurrence of membrane strains in double curvature over finite areas, reviews earlier work on the subject, discusses briefly the characterization of the properties of sheet materials and shows the approach to the problem through simple three-fold buckling. A major section of the paper relates to order-of-magnitude estimates of bending, membrane and gravitational energies and introduces two important dimensionless groups, J₁ = Yl²/D and J₂ = γgl³/D, in terms of which deformed shapes can be calculated. A mathematical model for three-fold buckling is described and the contributions of different energies during deformations are presented.     

Diagnostic and prognostic significance of the lymphocyte/C-reactive protein ratio,neutrophil/lymphocyte ratio,and D-dimer values in patients with COVID-19

In this study, our aim was to examine the diagnostic and prognostic significance of lymphocyte/C-reactive protein ratio (LCR), neutrophil/lymphocyte ratio (NLR) and D-dimer parameters in COVID-19 infection. The LCR, NLR, neutrophil count, mean platelet volume (MPV), C-reactive protein (CRP), and D-dimer parameters were evaluated retrospectively. This was a retrospective cohort study with 1000 COVID-19 positive and 1000 healthy control groups, all over the age of 18 years. Odds ratio (OR) and 95% confidence interval (CI) values were calculated for each parameter found to be statistically significant in the univariate and multivariate logistic regression models. Herein, 127 (12.7%) of the COVID-19⁺ patients, whose data was included in this study, died. The neutrophil, MPV, CRP, D-dimer, and NLR values were higher in the COVID-19⁺/deceased group than in the COVID-19⁺/alive and control groups (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001). The lymphocyte and LCR values were lower in the COVID-19⁺/deceased group than in the COVID-19⁺/alive and control groups (p < 0.001, p < 0.001). Variables with statistically significance in predicting COVID-19 infection were lymphocyte, LCR, D-dimer, NLR, CRP, MPV, PLT, and neutrophil values. Statistically significant variables in predicting mortality due to COVID-19 were LCR, CRP, NLR, lymphocyte, D-dimer, neutrophil, and MPV values. A low LCR and high NLR are associated with the presence, prognosis, and mortality due to COVID-19. LCR and NLR parameters can thus be used in clinical monitoring to reduce morbidity and mortality rates.     

Immunohistochemical and ultrastructural evidence of functional organization along the Corydoras paleatus intestine

The Neotropical catfish, Corydoras paleatus (Callichthyidae) is a facultative air‐breathing teleost that makes use of the caudal portion of the intestine as an accessory air‐breathing organ. This portion is highly modified, being well vascularized with capillaries between epithelial cells, which makes it well suited for gas exchange. Instead, the cranial portion is a digestion and absorption site, as it has a typical intestinal epithelium with columnar cells arranged in a single row, villi and less vascularized tunica mucosa. Therefore, the intestine was studied by light and electron microscopy to assess differences between the cranial, middle and caudal portions. To characterize the potential for cell proliferation of this organ, we used anti‐proliferating cell nuclear antigen antibody and anti‐Na⁺K⁺‐ATPase monoclonal antibody to detect the presence of Na⁺/K⁺ pump. In C. paleatus it was observed that cell dynamics showed a decreasing gradient of proliferation in cranio‐caudal direction. Also, the intestine of this catfish is an important organ in ionoregulation: the basolateral Na⁺/K⁺ pump may have an active role, transporting Na⁺ out of the cell while helping to maintain the repose potential and to regulate cellular volume. Microsc. Res. Tech. 79:140–148, 2016. © 2016 Wiley Periodicals, Inc.