Stereo Zoom Microscope Research Articles

Optimization of the properties of MOVPE-grown GaP epitaxial layers on GaP (1 1 1)B substrates

Gallium phosphide (GaP) homoepitaxial layers are optimized by varying the growth temperature, growth rate and V/III ratio in a low-pressure metal organic vapour phase epitaxy (MOVPE) process. It is observed that we need high growth temperature, low growth rate and an optimum value of the V/III ratio in order to obtain a mirror finish surface morphology. The surface morphology is mirror finish for an epitaxial layer grown ⩾820 °C when viewed under a stereo-zoom microscope for a V/III ratio of about 100 or more. A sharp and intense excitonic photoluminescence (PL) feature and a fine structure associated with donor–acceptor pair recombination confirm a high optical quality of the grown layer, which is supported by high-resolution x-ray diffraction measurements. For silicon doping of GaP using silane in low-pressure MOVPE, our results confirm theoretical predictions available in the literature and the values of a distribution coefficient lie in a similar range known for other conventional semiconductors. This optimization provides high-quality GaP (1 1 1)B epilayers needed for the development of either nanostructure-based optoelectronic devices on transparent substrates or polarization-sensitive infrared photodetectors based on two-photon absorption.

Evaluation of Surgically Retrieved Temporomandibular Joint Alloplastic Implants: Pilot Study

The purpose of this study was to perform a retrieval analysis of temporomandibular joint (TMJ) alloplastic interpositional implants and test possible correlation between implant failure features and patient clinical outcomes. In addition, we investigated the implants' surface and examined the foreign body reaction associated with different types of alloplastic materials. Twelve implants (Proplast/Teflon [Vitek, Houston, TX] and Silastic [Dow Corning, Midland, MI]) were surgically removed from the patients' TMJs. Implant surface failure features (fracture length, perforation of the implants) were observed using stereomicroscopy and recorded for description of the failure mechanisms and to statistically compare with clinical outcomes. Patients' clinical data (pain symptoms and mandibular function) were collected and examined. Clinical outcomes were obtained relative to symptom severity (Symptom Severity Index [SSI]) and jaw function (modified Mandibular Function Impairment Questionnaire [mMFIQ]). Peri-implant soft tissues and implants were analyzed with light microscopy and stereo zoom microscopy. Electron microprobe analysis of implant fragments and peri-implant tissues was performed. The statistical results showed that only the presence of implant perforation was statistically associated with the SSI, specifically with the pain tolerability dimension. No statistical association was seen between any of the other implant failure predictors and the SSI and between the predictors and the mMFIQ. Stereo zoom microscopy suggested that Proplast/Teflon implants (n = 7) were susceptible to perforation, layer tearing, fracture and fiber extrusion. The Silastic implants (n = 3) revealed a possible center perforation with fracture lines towards the periphery and fiber extrusion. Teflon implant wear debris particles appear to trigger a multinucleated giant cell foreign body reaction. Facial pain was a significant correlate to perforation and breakdown of the alloplastic TMJ interpositional implants, and most likely was the reason for implant removal.

Fabrication of Polysaccharide-inorganic Hybrid Biocapsules with Improved Catalytic Activity and Stability

In this study, a novel kind of calcium phosphate-mineralized chitosan/alginate microscapsules was prepared through a bio-inspired process for efficient encapsulation of yeast alcohol dehydrogenase (YADH). In this biomimetic process, when Ca2+-containing chitosan droplets were added into phosphate-containing solution of alginate, a thin chitosan/alginate film formed immediately around the microcapsules coupled with in situ precipitation of calcium phosphate. The biomineralization of calcium phosphate was mimicked by the counter-diffusion system in which Ca2+ ions and phosphate ions migrated into the chitosan/alginate film from opposite directions, respectively. Formation of a microcapsule was confirmed using a Zoom Stereo Microscope, the surface morphology of the microcapsule was characterized by SEM, the surface element composition of microcapsules was analyzed by XPS, and the pore-size distribution of the microcapsule shell was determined by BET. YADH encapsulated in the microcapsules exhibited significantly higher activity and recycling stability in a broader temperature range than the free YADH. We believe that such hybrid materials will find promising applications in enzyme encapsulation and drug delivery systems.

Crack-tip strain fields in collagen biomaterials for skin tissue engineering

Abstract The objective of this investigation was to determine the notch-tip strain fields in Type-I collagen biomaterials. Experiments were performed in-situ in a fixture mounted on the stage of an optical stereozoom microscope with edge-notched Type-I collagen tensile specimens. Image markers were added around the notch, and a tensile strain was applied. High-resolution images were collected at different levels of far-field strain. Image analysis was performed to measure the displacements of individual surface markers. The resultant displacement fields were analyzed to yield in-plane surface strain profiles along trajectories perpendicular to the crack plane. The results revealed significant local strain amplifications near the notch tip of nearly twenty times. These results are discussed in light of existing constitutive models for crack-tip strain fields.

Fracture toughness of a ceramic–resin interface

Objectives The purpose of this study was to compare the interfacial fracture toughness of smooth and roughened ceramic surfaces bonded with a luting resin using an optimized method of silane treatment. Methods Ceramic discs were prepared with four different surface preparations ( n = 20) consisting of (1) polished, (2) gritblasted, (3) hydrofluoric acid etched and (4) gritblasted and etched. The ceramic discs were then covered by a PTFE tape with a chevron shaped circular hole. The exposed surfaces were treated by an optimized silane treatment followed by an unfilled resin and then a luting resin. Specimens were then stored in distilled water at 37 °C for (A) 24 h and (B) 30 days. The interfacial fracture toughness was measured, the mode of failure and fracture surfaces were also examined under a stereo-zoom microscope and a scanning electron microscope. Results One-way ANOVA showed that there was no statistically significant difference in the mean interfacial fracture toughness for groups A1–A4 ( P > 0.05). However, the mean interfacial fracture toughness for group B1 was significantly different from that for groups B2, B3 and B4 ( P < 0.05). Independent-samples t-test results showed that there was a significant increase in the G Ic mean value for groups B2 and B3 after 30 days water storage ( P < 0.05). The modes of failure were predominantly interfacial or cohesive within the resin. Significance It can be concluded that micro-mechanical retention by gritblasting the ceramic surfaces could be sufficient with no need for HF acid etching the ceramic surfaces when an appropriate silane application procedure is used.

English

Quality of the electronic assembly depends largely on good quality practices (GQP) adopted during the process of electronic assembly. Quality experiences gained during working at the defence and space laboratories have been used to develop good quality practices such as three- tray method for cleaning of PCBs, use of grommets for cable routing, use of eye-pieceless stereo zoom microscope for visual testinglinspection, pre-tinning of components, desiccators for storage, potting prior to conformal coating, continuity and isolation checks, de-golding of leads prior to soldering, and use of flux-cored solder wire. The paper also discusses how and why these good quality practices were evolved.

A preliminary evaluation of the surface of surgically removed Proplast/Teflon interpositional disc implants from human temporomandibular joints

A preliminary evaluation of the surface of surgically removed Proplast/Teflon interpositional disc implants from human temporomandibular joints

195 DEVELOPMENT OF INNER CELL MASS AND FORMATION OF EMBRYOID BODIES ON A GELATIN-COATED DISH AND ON THE FEEDER LAYER IN BUFFALO (BUBALUS BUBALIS)

Isolation and culture of embryo-derived cell lines have been reported in many mammals, however, there is not even a single report toward initiation of such work in buffalo (Bubalus bubalis). Therefore the present study was carried out to isolate the inner cell mass from in vitro-produced buffalo blastocysts and to grow this inner cell mass for formation of embryoid bodies in a gelatin-coated dish and on an homologous fetal fibroblast feeder layer. Immature buffalo oocytes were isolated from the slaughterhouse ovaries. In vitro production of blastocysts was carried as reported by Chauhan et al. (1999 J. Dairy Science 82, 918-926). A total of 26 buffalo blastocysts were produced in vitro. These blastocysts were transferred into a 100-mL drop of Dulbecco's modified Eagle's medium (DMEM) supplemented with 20% fetal bovine serum (FBS) for further culturing. Thirteen blastocysts hatched on the next day of culture. The hatched mass was separated, suspended in Dulbecco's phosphate buffer saline (DPBS, without Ca++ and Mg++) containing 5% FBS + 0.25% trypsin and examined under the zoom stereomicroscope until disappearance of the trophectoderm cells. The remaining cells of seven blastocysts were cultured in DMEM supplemented with 20% FBS on 0.2% gelatin coated culture dish (group 1), and cells of six blastocysts in DMEM medium supplemented with 20% FBS were cultured on a mitomycin-c-treated (10 �L/mL) feeder layer (group 2), for 14 days. The isolated cells attached to the bottom of the dish in both the groups, spreading was noticed on Day 5 of the culture in group 1 and on Day 3 of culture in group 2. The attached cells were trypsinized using DPBS with 0.25% trypsin, isolated, and subcultured further. Attachment and spreading was noticed only in group 2 subcultured cells. The cellular integrity was homogeneous and the plasma membrane was clearly visible in group 2, but not in group 1. Less than 10% of the attached cells formed embryoid bodies in group 1, where as more than 30% attached cells in group 2 formed embryoid bodies; the latter expressed alkaline phosphatase activity and were blue after staining. These results indicate that the culturing of the inner cell mass on an homologous fetal fibroblast feeder layer is a better choice for production of embryonic stem cells in buffaloes.

Morphological Studies of the Predatory Ladybird Beetle Stethorus vagans (Blackburn) (Coleoptera: Coccinellidae)

Morphological features of the ladybird beetle Stethorus vagans (Blackburn) were studied at 25 ± 2°C with a photoperiod of 16L: 8D. All stages of S. vagans were examined under a stereo-zoom microscope. Newly laid eggs were translucent white, turning pale yellow after 4–5 hours. The mean egg dimension was 0.36 × 0.19 mm. Eggs laid by unmated females did not hatch or show any signs of development. Newly emerged larvae were white in color, but soon became pale creamy-white. There were four larval instars, which were differentiated from each other by the presence of exuviae and differences in head capsule size. The pre-pupa, not a distinct stage in the life cycle but a quiescent period at the end of the 4th larval instar, lasted for several hours. Pupae were oval, flattened and black-brown with fine hair like setae on their dorsal sides with a mean length and width of 1.06 × 0.74 mm. The adults were oval, convex and black with small yellow setae on their dorsal side.

Secretory Proteins from Goat Oocytes Matured in Culture

In this experiment, oocytes were collected from goat ovaries available in slaughterhouse by follicle puncture method. Morphologically culturable type of oocytes which having compact, multilayered cumulus granulosa cell complex and evenly granulated cytoplasm, was separated under a stereozoom microscope. Oocytes were washed thoroughly in maturation medium containing TCM-199, 1 µg/ml estradiol-17β, 0.5 µg/ml FSH, 100 µg/ml LH, 3 mg/ml BSA and 10% estrus goat serum. Washed oocytes were cultured into maturation medium on granulosa cell monolayer. Culture plate was then kept into CO2 incubator at 38±1°C, maximum humidity and 5% CO2 for 18 h. After maturation the oocytes were washed thoroughly with maturation medium containing polyvinyl alcohol (PVA) without serum and BSA and further cultured for 12 h for secretory proteins of oocytes. PVA medium was collected, pooled and concentrated by 5000 cut off centrisart. Secretory proteins were separated on 12.5% SDS-PAGE. A total number of 3.41 oocytes per ovary were obtained and 2.17 culturable oocytes per ovary were cultured into maturation medium. After 18 h of maturation, 4,567 oocytes (1.82 oocytes per ovary) were further cultured into serum and BSA free PVA medium for its secretory proteins. Four secretory proteins of oocytes with approximately molecular weight of 45, 55, 65 and 95 kDa were obtained on SDS-PAGE in silver staining and three proteins with approximately molecular weight of 45, 55 and 65 kDa in Coomassie brilliant blue staining. In conclusion, four secretory proteins with approximately molecular weight of 45, 55, 65 and 95 kDa was obtained from in vitro cultured oocytes of goats. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 3 : 340-345)

Timing of sequential changes in cumulus cells and first polar body extrusion during in vitro maturation of buffalo oocytes

Studies were conducted to investigate the degree of the cumulus cell expansion and expulsion of the first polar body in relation to time of incubation in three different culture media during in vitro maturation of buffalo oocytes and to suggest a suitable practical method for assessment of in vitro maturation rate of buffalo oocytes. Buffalo oocytes were aspirated from ovaries collected from a local slaughterhouse. Only oocytes with more than two layers of cumulus cells and homogenous ooplasm were cultured into 50 μl droplets of three different culture systems: (1) TCM-199+steer serum (10%); (2) TCM-199+steer serum (10%)+PMSG (40 IU/ml); and (3) TCM-199+steer serum (10%)+PMSG (40 IU/ ml)+ estradiol 17β (1 μg/ml) in a 35 mm Petri dish. The droplets were covered with warm (39 °C) mineral oil and incubated in a CO 2 incubator (39 °C, 5% CO 2 in air, 90–95% relative humidity) for 16–18, 20, 22, and 24 h. The maturation rate was assessed by evaluation of degree of cumulus cells expansion and identifying first polar body extrusion into the perivitelline space under stereo zoom microscope. Matured oocytes were inseminated in vitro with 9–10 million sperm/ml of Brackett and Oliphant (BO) medium. Cleaved embryos were cultured in TCM-199 supplemented with steer serum (10%) for 8 days. Cumulus expansion and extrusion of first polar body commenced at 16 and 17 h, respectively, of buffalo oocyte culture. These events mainly exhibited during 22–24 h of culture. Oocytes with Degrees 1 and 2 cumulus cells expansion and extruded first polar body in degree 0 oocytes may be considered as matured and can be used in IVF studies.

Micromechanical characterization of cellulose fibers

The work presented here aims towards the characterization of micromechanical properties of individual cellulose fibers. In particular, our interest is in determining the elastic modulus, tensile strength and tensile elongation of cotton and wood based cellulose fibers. Testing is conducted at a microscale, on single fibers of a few millimeters in length and tens of microns in width, a scale so chosen because such fibers are commonly used as industrial raw materials. An in-house microtensile fiber tester was designed and fabricated. A fine resolution stepper motor (10 nm per step) provides the actuation for the microtensile load frame and load in the fibers is measured by a high sensitivity load cell (0.01 mN resolution). The entire assembly is placed below a zoom stereo microscope for the dual purpose of aiding in specimen mounting and visually recording the experiment. After calibration of the device, good results were obtained when testing both the cotton and wood based cellulose fibers. Average Young's moduli of 4 GPa and 2 GPa were found for the two fibers, respectively. However, a large variation in failure stress was found for the fibers of both kinds, necessitating a statistical analysis assuming a Weibull distribution of failure. Based on this, mean strengths of 496 MPa for cotton cellulose fibers and 164 MPa for wood cellulose fibers were obtained.

One-grating projection for absolute three-dimensional profiling

A new method for absolute 3-D profiling, based on the fringe projection technique using a vertical scan mode, is described. With a combined measurement of the modulation and the phase it is possible to acquire the topography without any ambiguity problems by using one grating period only. Consequently, the vertical measurement range is limited only by the free working distance and the resolution is compa- rable to standard fringe projection techniques. We present a microscopic solution, based on a zoom stereo microscope, which enables interesting applications in an extended microscopic range, such as the measure- ment of microcomponents and microshapes, for example. © 2001 Society

Observations on the Oviposition Process of Diaprepes abbreviatus (Coleoptera: Curculionidae)

A single adult Diaprepes abbreviatus L. was discovered in a citrus nursery in Orange County Florida (Woodruff 1964). D. abbreviatus was not collected again until 1968, when larvae were collected at the same nursery and several hundred adults and larvae were subsequently collected in and around Apopka, FL (Woodruff 1968). Since its introduction in 1964, D. abbreviatus has spread to 20 counties in Florida, where it currently infests approximately 164,000 acres (66,420 ha) (Anonymous 1997). This area contains approximately 30,000 acres (12,150 ha) of infested commercial citrus and has a limited and localized geographical distribution. D. abbreviatus is an insidious pest; tree symptoms may not appear until the larvae are well established on the tree roots (Wolcott, 1936). Adults feed on young foliage, females lay egg clusters between leaves, and the larvae feed on the roots of a host (Fennah 1942, Jones 1915, Wolcott 1936, Woodruff 1968). Oviposition by D. abbreviatus appears to be restricted to nighttime hours (Jones 1915, Schroeder 1981, Wolcott 1936). Females oviposit approximately 60 egg masses during their lifetime which may contain from 30 to 260 eggs each and an average of about 5,000 eggs over their life span (Wolcott 1936). Wolcott (1933) observed that female D. abbreviatus preferred to oviposit between paper strips compared to leaves. Neonate larvae failed to emerge from these strips (Wolcott 1933). Fennah (1942) found that D. abbreviatus preferred paper strips over tin foil strips and mature leaves which were both favored over immature leaves for oviposition. Immature leaves are preferred feeding sites (Jones 1915, Wolcott 1936). Adair et al. (1998) reported that freezer paper strips might serve as a potential oviposition trap in citrus. Adult D. abbreviatus were field collected in Vero Beach, Florida and maintained as previously described (Adair et al. 1998). Thirty females and 30 males per cage were held in 30 x 30 x 60 cm aluminum rearing cages (Bioquip Products, Gardena, CA 90248-3602) at 27 ? 2?C, 30% RH and photoperiod of 11:13 (L:D). Five 2.54 cm x 15.24 cm doubled strips of transparency film (polyester, Labelon, Canadaigua, NY 14424) were provided for oviposition sites. At 10:00 PM, transparency film strips containing an ovipositing female were removed to a microscope stage for observation and photographing. Microscopic observations were conducted with an Olympus S2-6045 zoom stereo microscope with a 100AL 0.5x objective lens, lOx eyepiece and a NFK 2.5 x LD 125 lens and Olympus S2-PT (with L-adapter) adapter for a SLR camera. An Olympus OM 2S camera with automatic shutter speed and f-stop was used with Kodak Kodacolor 400 Gold? film. The transparency film strip with an ovipositing female was placed across an open Petri dish and illuminated above and below with a tungsten halogen lamp (Olympus Highlight 3000) equipped with bifurcating cold fiber optic goose neck

Optical roughness measurements with fringe projection

The characterization of roughness of engineering surfaces over an area is an important task for different applications as well as for manufacturing processes. The surface roughness is in particular an important factor in determining the performance of a workpiece. We demonstrate that the fringe projection technique allows very fast three-dimensional surface inspections. The inspection time for an entire measurement is reduced to less than 5 s with standard hardware. Based on a zoom stereo microscope setup, we demonstrate a modular measuring instrument. The magnification-dependent vertical resolution can be as high as 0.1 microm. The special properties for roughness measurements are demonstrated, especially the comparability with a tactile sensor and with other optical sensors, which is discussed in connection with amplitude parameters.

Rate-related fatigue injury of vertebral disc under axial cyclic loading in a porcine body-disc-body unit

Objective. Cyclic loading tests were performed on fresh mature porcine lumbar spines to investigate the mechanical responses at different loading rates, morphological changes in the disc and to produce the clinically relevant injuries of porcine intervertebral disc. Design. Two-segment units of fresh porcine spine with all the posterior elements removed were used for a disc stress analysis and morphological observation during axial cyclic loading. Background. The repetitive loading of the spine has been implicated as a risk factor in developing low back disorders. However, few studies have discussed morphologic changes in vertebral disc due to fatigue stress and no study has investigated the relationship between disc strength and bone mineral density. Methods. 21 body-disc-body specimens divided into three groups were subjected to cyclic loading at test speeds of 0.5, 5 and 20 mm min −1. The correlation between residual stress of specimen and bone mineral density was investigated and the disc morphological changes were observed through the middle cross section of the intervertebral disc using a zoom stereo microscope. Results. There was no visible crack observed following testing in the 0.5 mm min −1 test group. However, one disc in the 5 mm min −1 and two discs in the 20 mm min −1 test group exhibited disc herniation. The residual stress was found to be positively and linearly correlated with bone mineral density and decreased as the loading rates increased. Conclusion. Faster loading rate generates greater stress decay, and disc herniation is more likely to occur under higher loading rate conditions. The most common site of disc herniation is the posterolateral area which is in agreement with that of the human spine.

Distribution and regional strength of trabecular bone in the porcine lumbar spine

Objective. The regional strength and distribution of trabecular bone in the porcine lumbar spine were examined to understand the mechanical responses in quadrupedal vertebrae. Design. The cancellous bone columns prepared from different regions of porcine lumbar vertebrae were subjected to axial compression to investigate the regional strength related to disc structure. Some vertebrae were also serially sectioned sagittally and transversely to observe the trabecular patterns. Background. Animal spines were often used in biomechanical testing and the results were said to be similar to those of humans. However, none of them are truly like human bipedal locomotion. The understanding of regional variations in compressive properties may help us to explain the similarity and interpret the data of animal experiments. Methods. The dried, defatted cancellous bone columns were subjected to uniaxial compression of different regions at a deformation rate of 5 mm/min. The mechanical properties in different regions were compared. The main trabecular orientation was also observed using a zoom stereo microscope. Results. The ultimate strength of the posterior column tended to be larger than that of the anterior column. The ratio of bony strength overlying the nucleus pulposus to that overlying the annulus fibrosis was constant and averaged 1.16. The main trabecular struts were noted to be parallel to the spinal canal and cross-bridged by thinner trabeculae. Conclusions. The trabecular morphology and regional mechanical properties of the porcine spine were comparable to those of other similar studies on the human spine. Its significance needed further study.

Design of a high-resolution stereo zoom microscope

A stepped magnification stereo microscope and a stereo zoom microscope are designed and fabricated using a modular concept. A resolution of 4 ?m is achieved with both instruments. The design details are discussed.

Release of carbon granules from cigarettes with charcoal filters.

ObjectiveTo inspect cigarettes with a triple granular filter for charcoal granules on the cut filter surface and, if present, to determine whether the charcoal granules on the filter are released...

Soft tissue response to proplast-teflon and silicone in humans: Morphological and immunohistochemical observations

The purpose of this study was to perform a retrieval analysis of temporomandibular joint (TMJ) alloplastic interpositional implants and test possible correlation between implant failure features and patient clinical outcomes. In addition, we investigated the implants' surface and examined the foreign body reaction associated with different types of alloplastic materials.Twelve implants (Proplast/Teflon [Vitek, Houston, TX] and Silastic [Dow Corning, Midland, MI]) were surgically removed from the patients' TMJs. Implant surface failure features (fracture length, perforation of the implants) were observed using stereomicroscopy and recorded for description of the failure mechanisms and to statistically compare with clinical outcomes. Patients' clinical data (pain symptoms and mandibular function) were collected and examined. Clinical outcomes were obtained relative to symptom severity (Symptom Severity Index [SSI]) and jaw function (modified Mandibular Function Impairment Questionnaire [mMFIQ]). Peri-implant soft tissues and implants were analyzed with light microscopy and stereo zoom microscopy. Electron microprobe analysis of implant fragments and peri-implant tissues was performed.The statistical results showed that only the presence of implant perforation was statistically associated with the SSI, specifically with the pain tolerability dimension. No statistical association was seen between any of the other implant failure predictors and the SSI and between the predictors and the mMFIQ. Stereo zoom microscopy suggested that Proplast/Teflon implants (n = 7) were susceptible to perforation, layer tearing, fracture and fiber extrusion. The Silastic implants (n = 3) revealed a possible center perforation with fracture lines towards the periphery and fiber extrusion. Teflon implant wear debris particles appear to trigger a multinucleated giant cell foreign body reaction.Facial pain was a significant correlate to perforation and breakdown of the alloplastic TMJ interpositional implants, and most likely was the reason for implant removal.