Polycarbonate Tube Research Articles

Measuring Small Airways in Transverse CT Images: Correction for Partial Volume Averaging and Airway Tilt

Airway wall dimensions can be determined in vivo using transverse computed tomographic (CT) images, but the measurement of airway phantoms shows that the wall thickness is consistently overestimated for small airways. This phantom study was performed to derive and test corrections to the measurements on the basis of consideration of partial volume averaging and tilt effects.A lung phantom with six polycarbonate tubes embedded in foam was scanned, and the cross-sectional dimensions of the tubes were determined using the full width at half maximum, zero crossing, and phase congruency edge detection methods. Equations were derived using the reported wall intensity to correct for partial volume averaging. Corrections for the overestimation of the wall thickness due to the tilt of the tube with respect to the CT z-axis were also derived.All three methods (full width at half maximum, zero crossing, and phase congruency) overestimated the wall thickness of the small polycarbonate tubes. It was verified that two sources of error were partial volume averaging and tilt that was introduced when the phantom was positioned with tube axes at an angle to the CT z-axis. The corrections were applied to the measured tube wall dimensions and substantially reduced the deviation of the CT measurements from the true values.Correcting for partial volume effects and airway tilt greatly increases the accuracy of simulated airway wall measurements in transverse CT images.

A rechargeable lithium-ion battery module for underwater use

Portable underwater electrical power is needed for many commercial, recreational and military applications. A battery system is currently not available to meet these needs, which was the aim of this project. Lithium-ion battery cells (Panasonic (CGR18650E)) were chosen, based on their high energy density and availability. To increase their voltage, 8 battery cells were connected in series (“sticks”) and protected by encapsulating them into a polycarbonate tube; and 6 sticks were housed inside a triangular aluminum case (module). Testing was performed to determine the consistency of individual cells, sticks and module and during discharge/charging cycles. The effect of ambient temperature ( T A) was determined by instrumenting them with thermocouples. In addition, voltage and current were measured and used to determine the heat generated within the battery cell and were compared to theory. From these data, a radial temperature profile was determined for two battery sticks in the battery module. Collapse pressure was determined and compared to theory. The Panasonic (CGR18650E) cells delivered 2291 mAh each over a wide range of T A and discharge/charge rates. The theoretical and experimental data showed that the temperature within the battery sticks and modules did not rise above or below their operating temperature range (−20 and 60 °C), in agreement with the models. The tubes encapsulating the sticks withstood pressures down to 305 m of sea water (msw) which was predicted by modeling. The Panasonic (CGR18650E) cells, sticks and module demonstrated that they provided sufficient electrical power, reliably and safely to be used in the underwater environment (1800–2000 kPa, 305 msw) over a wide range T A, including high power requirement systems like an active thermal protection system that keeps a diver comfortable in extreme temperature conditions. The concept developed here can be modified to meet specific power requirements by varying the number of cell in series to achieve the desired voltage, and the number of sticks in parallel to provide the current capacity required.

Comparative Structural Biology of Eubacterial and Archaeal Oligosaccharyltransferases

Oligosaccharyltransferase (OST) catalyzes the transfer of an oligosaccharide from a lipid donor to an asparagine residue in nascent polypeptide chains. In the bacterium Campylobacter jejuni, a single-subunit membrane protein, PglB, catalyzes N-glycosylation. We report the 2.8 A resolution crystal structure of the C-terminal globular domain of PglB and its comparison with the previously determined structure from the archaeon Pyrococcus AglB. The two distantly related oligosaccharyltransferases share unexpected structural similarity beyond that expected from the sequence comparison. The common architecture of the putative catalytic sites revealed a new catalytic motif in PglB. Site-directed mutagenesis analyses confirmed the contribution of this motif to the catalytic function. Bacterial PglB and archaeal AglB constitute a protein family of the catalytic subunit of OST along with STT3 from eukaryotes. A structure-aided multiple sequence alignment of the STT3/PglB/AglB protein family revealed three types of OST catalytic centers. This novel classification will provide a useful framework for understanding the enzymatic properties of the OST enzymes from Eukarya, Archaea, and Bacteria.

A 3mm endoscopic probe with integrated MEMS micromirror for optical coherence tomography bioimaging

A 3mm diameter endoscopic probe for Optical Coherence Tomography (OCT) has been developed. It consists of a 1 mm diameter micromirror, a silicon optical bench (SiOB), a gradient refractive index (GRIN) lens and a single mode optical fiber. The optical probe is enclosed within a biocompatible, transparent and waterproof polycarbonate tube for in vivo diagnostic applications. The two-axis scanning micromirror is driven by electrothermal actuators with a voltage less than 2 V for a mechanical deflection of up to 11∘. By integrating the MEMS micromirror with a commercial Optical Coherence Tomography system and miniaturized probe, high resolution 2-D/3-D in vivo and in situ images and excellent optical sectioning for imaging multilayer microstructures of internal organs can be realized. The capability of the system is demonstrated by obtaining a 2-D image of an onion.

A Frequency Reconfigurable Dielectric Resonator Antenna Using Colloidal Dispersions

The vertical displacement of a columnar fluidic colloidal dispersion is examined as a frequency reconfigurable dielectric resonator antenna (DRA). The coaxial probe-fed structure has tunable impedance properties that are reversibly controlled by adjusting the columnar height of the dispersion. Colloidal barium strontium titanate was dispersed in hydrotreated naphthenic oil and placed at several heights into a section of polycarbonate tubing over an aluminum ground plane to demonstrate the impedance properties of this structure. Measured, simulated, and calculated results for a range of heights that corresponded to single-mode operation are provided for a design operating between 2.5 and 4.5 GHz.

Variable volume piezometer for measurement of volumetric properties of materials under high pressure

A piezometer was designed to measure volume change of foods and other biomaterials as a function of pressure, and calibrated and tested up to 700 MPa at 25°C. The sensor was constructed from a polycarbonate tube, sealed with a plug on one end and a removable piston on the other. Samples were placed inside the tube. Upon pressurization, the piston displaced inside the tube, transmitting pressure to the sample; impedance in a magnet wire coil on the outside of the tube was measured to characterize volume change. Sensor calibration with water yielded a polynomial that characterized volume as a function of impedance. Sensor precision is 0.3% of measured volume; its resolution allows measurement of sub-microliter volume changes. Testing with ethanol and sucrose solutions yielded data within 1% of previously reported values. The sensor's applications include measurement of volumetric properties of liquid and solid biomaterials, and chemical reaction volumes.

Airway wall attenuation: a biomarker of airway disease in subjects with COPD

The computed tomographic (CT) densities of imaged structures are a function of the CT scanning protocol, the structure size, and the structure density. For objects that are of a dimension similar to the scanner point spread function, CT will underestimate true structure density. Prior investigation suggests that this process, termed contrast reduction, could be used to estimate the strength of thin structures, such as cortical bone. In this investigation, we endeavored to exploit this process to provide a CT-based measure of airway disease that can assess changes in airway wall thickening and density that may be associated with the mural remodeling process in subjects with chronic obstructive pulmonary disease (COPD). An initial computer-based study using a range of simulated airway wall sizes and densities suggested that CT measures of airway wall attenuation could detect changes in both wall thickness and structure density. A second phantom-based study was performed using a series of polycarbonate tubes of known density. The results of this again demonstrated the process of contrast reduction and further validated the computer-based simulation. Finally, measures of airway wall attenuation, wall thickness, and wall area (WA) divided by total cross-sectional area, WA percent (WA%), were performed in a cohort of 224 subjects with COPD and correlated with spirometric measures of lung function. The results of this analysis demonstrated that wall attenuation is comparable to WA% in predicting lung function on univariate correlation and remain as a statistically significant correlate to the percent forced expiratory volume in 1 s predicted when adjusted for measures of both emphysema and WA%. These latter findings suggest that the quantitative assessment of airway wall attenuation may offer complementary information to WA% in characterizing airway disease in subjects with COPD.

Impact compressive response of dry sand

A split Hopkinson pressure bar (SHPB) was properly modified to obtain dynamic compressive stress–strain curves of dry sand at various high strain rates. Quasi-static compressive properties of the sand were obtained with a MTS810 materials test system. In both dynamic and quasi-static experiments, the 1.50 × 10 3 kg/m 3 dry sand, confined with a polycarbonate tube, had the same dimensions, making the strain rate the only variable. The strain rate effects on the compressive response of the sand were determined. The sand was also prepared to specimens with a higher initial density of 1.62 × 10 3 kg/m 3 for dynamic experiments to investigate the initial density (gas porosity) effects. At a given dynamic strain rate, besides using the polycarbonate confining tube, polyolefin heat shrinking tubes and 4340 steel tubes were used to confine the sand specimens to study the lateral confinement effects. The results show that the compressive response of the dry sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the initial density and lateral confinement level.

Design and development of a 3D scanning MEMS OCT probe using a novel SiOB package assembly

A MEMS optical coherence tomography (OCT) probe prototype was developed using a unique assembly based on silicon optical bench (SiOB) methodology. The probe is formed by integrating a three-dimensional (3D) scanning micromirror, gradient refractive index (GRIN) lens and optical fiber on SiOB substrates having prefabricated self-aligned slots. The two-axis scanning micromirror is based on electrothermal actuation with required voltage less than 2 V for mechanical deflections up to 17°. The optical probe was enclosed within a biocompatible, transparent and waterproof polycarbonate tube with a view of in vivo diagnostic applications. The diameter of the miniature probe is less than 4 mm and the length of its rigid part is about 25 mm. The probe engineering and proof of concept of the probe were demonstrated by obtaining en face and three-dimensional OCT images of an IR card used as a standard sample.

The effect of pH on surface hardness and microstructure of mineral trioxide aggregate

To evaluate the surface microhardness of mineral trioxide aggregate (MTA) specimens following exposure of their surface to a range of acidic environments during hydration. In addition, the morphological microstructure features of samples were studied by scanning electron microscopy (SEM). White ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed and packed into cylindrical polycarbonate tubes. Four groups, each of 10 specimens, were formed using a pressure of 3.22 MPa and exposed to pH 4.4, 5.4, 6.4 and 7.4, respectively, for 4 days. Vickers microhardness of the surface of each specimen was measured after exposure. Four groups of two specimens were prepared and treated in the same way prior to qualitative examination by SEM. Data were subjected to one-way anova and post hoc Tukey's test. The greatest mean surface hardness values (53.19 +/- 4.124) were observed following exposure to pH 7.4 with the values decreasing to 14.34 +/- 6.477 following exposure to pH 4.4. The difference between these values at the 95% CI (33.39-44.30) was statistically significant (P < 0.0001). There were no distinct morphological differences between groups in terms of the internal microstructure. However, a trend was observed that the more acidic the solution, the more extensive the porosity of the specimens. Under the conditions of this study, surface hardness of MTA was impaired in an acidic environment.

Proteomic analysis of platelet alpha-granules using mass spectrometry.

Platelets have three major types of secretory organelles: lysosomes, dense granules, and alpha-granules. alpha-Granules contain several adhesive proteins involved in hemostasis, as well as glycoproteins involved in inflammation, wound healing, and cell-matrix interactions. This article represents the first effort to define the platelet alpha-granule proteome using mass spectrometry (MS). We prepared a subcellular fraction enriched in intact alpha-granules from human platelets using sucrose gradient ultracentrifugation. alpha-Granule proteins were separated and identified using sodium dodecylsulfate polyacrylamide gel electrophoresis and liquid chromatography-tandem MS. In the sucrose fraction enriched in alpha-granules, we identified 284 non-redundant proteins, 44 of which appear to be new alpha-granule proteins, on the basis of a literature review. Immunoelectron microscopy confirmed the presence of Scamp2, APLP2, ESAM and LAMA5 in platelet alpha-granules for the first time. We identified 65% of the same proteins that were detected in the platelet releasate (J. A. Coppinger et al. [Blood 2004;103: 2096-104]) as well as additional soluble and membrane proteins. Our method provides a suitable tool for analyzing the granule proteome of patients with storage pool deficiencies.

The effect of condensation pressure on selected physical properties of mineral trioxide aggregate

To examine the effect of condensation pressure on surface hardness, microstructure and compressive strength of mineral trioxide aggregate (MTA). White ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed and packed into cylindrical polycarbonate tubes. Six groups each of 10 specimens were subjected to pressures of 0.06, 0.44, 1.68, 3.22, 4.46 and 8.88 MPa respectively. The surface hardness of each specimen was measured using Vickers microhardness. Cylindrical specimens of 4 mm in diameter and 6 mm in height were prepared in polycarbonate cylindrical moulds for testing the compressive strength. Five groups of 10 specimens were prepared using pressures of 0.06, 0.44, 1.68, 3.22 or 4.46 MPa. Data were subjected to one-way anova. The microstructure was analysed using a scanning electron microscope (SEM) after sectioning specimens with a scalpel. A trend was observed for higher condensation pressures to produce lower surface hardness values. A condensation pressure of 8.88 MPa produced specimens with significantly lower values in terms of surface hardness than other groups (P<0.001). A condensation pressure of 1.68 MPa conferred the maximum compressive strength; however, it was not statistically different. Higher condensation pressures resulted in fewer voids and microchannels when analysed with SEM. In specimens prepared with lower condensation pressures distinctive crystalline structures were observed. They tended to appear around microchannels. Condensation pressure may affect the strength and hardness of MTA. Use of controlled condensation pressure in sample preparation for future studies is suggested.

Chondroitin Sulfate N-Acetylgalactosaminyltransferase-1 Plays a Critical Role in Chondroitin Sulfate Synthesis in Cartilage

Cartilage destruction leads to severe joint diseases, such as osteoarthritis and spinal disorders with back pain, and cartilage regeneration is very inefficient. A major component of the cartilage extracellular matrix is the proteoglycan aggrecan that contains approximately 100 chondroitin sulfate (CS) chains, which impart water absorption and resistance to compression. Here, we demonstrate that chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1) plays a critical role in CS biosynthesis in cartilage. By in situ hybridization and real time reverse transcription-PCR of developing cartilage, CSGalNAcT-1 exhibited the highest level of expression. Its expression in chondrogenic ATDC5 cells correlated well with that of aggrecan core protein. In heterozygote and homozygote aggrecan-null cartilage where aggrecan transcription is decreased, CSGalNAcT-1 transcription diminished accordingly. Overexpression of the enzyme in chondrocytic cells further enhanced CS biosynthesis but not that of the aggrecan core protein, indicating that the enzyme activity is not saturated in the cells and that aggrecan synthesized in the overexpressing cells is heavier than the native molecule. Analysis of the CS chains synthesized in the overexpressing cells by gel chromatography and that of disaccharide composition revealed that the CS chains had similar length and sulfation patterns. Furthermore, adenoviral gene delivery of the enzyme into intervertebral discs displayed a substantial increase in the level of CS biosynthesis. These observations indicate that CSGalNAcT-1 overexpression increases the number of CS chains attached to aggrecan core protein. Our studies may lead to a new therapeutic intervention, ameliorating the outcome of cartilage degenerative diseases.

Consecutive solvent evaporation and co-rolling techniques for polymer multilayer hollow fiber preform fabrication

All-polymer multilayer hollow core photonic fiber preforms were fabricated using consecutive deposition from a solvent phase of two polymers with high and low refractive indices (RI). Processing techniques for two polymer pairs—polystyrene (PS)/poly(methyl methylacrylate) (PMMA) and polycarbonate (PC)/poly(vinylene difloride) (PVDF)—were established. The fabrication process involved consecutive film deposition by solvent evaporation of polymer solutions on the inside of a rotating PMMA or PC tube, used as a cladding material. By injecting right volumes of the polymer solutions into a spinning tube the thickness of each layer could be reliably controlled from 20 to 100 μm. Proper selection of solvents and processing conditions was crucial for ensuring high optical and mechanical quality of a resultant preform, as well as compatibility of different polymer films during co-deposition. Preforms of 10 layers for PMMA/PS material combination and 15 layers for PVDF/PC were demonstrated. Fabrication of preforms with higher number of layers is readily possible and is only a question of preform fabrication time. An alternative method of preform fabrication by co-rolling of polymer bilayers is also presented in this paper, drawing of PMMA/PS, PVDF/PC fibers with up to 32 layers is demonstrated.

Frass sampling and baiting indicate European earwig (Forficula auricularia) foraging in orchards

Abstract: Earwigs are significant generalist predators of a range of orchard pests, but quantitative assessment of earwig density and beneficial impact is difficult. A sampling system was designed and tested, based on field placement of polycarbonate tubes in apple trees as scotophase arboreal refugia. Tubes containing artificial diet and provided with a black plastic sleeve had the highest earwig counts. Tubes with diet or the black sleeve alone were less preferred. Presence of distinctive frass was also evident in polycarbonate tubes containing artificial diet, and earwig frass was recorded at a higher frequency than earwig presence, indicating foraging and detection of the tubes at a higher rate than their use as shelters. At the tree level, there was a weak correlation between frass abundance and predation rates on leafroller egg batches placed as baits in the canopy, but not with earwig density measured by corrugated cardboard rolls or diet tubes. Diet tubes have the potential to offer new insights into earwig foraging behaviour in orchards.

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IR-transmissive hollow waveguides have been fabricated by depositing Cu and CuI thin-film coatings inside silica and polycarbonate tubing. These guides, which are similar in design to Ag/AgI-coated ones, have straight losses as low as 0.19 dB/m for a 1000-µm-bore waveguide at 10.6 µm. They also transmit IR wavelengths from 2 to more than 15 µm. This makes them very useful for broadband IR applications, including chemical sensing and radiometry, as well as for use in the delivery of IR laser power for laser surgery and low-power cutting. The thin-film coatings are deposited using a liquid-chemistry technique in which a Cu film is first formed on the inside of the tubing, followed by the deposition of the dielectric CuI layer. The thickness of the CuI layer is adjusted to give low loss at specific IR laser wavelengths or to give a broadband response for the transmission of incoherent light.

Just scratching the surface

Different types of polymer surfaces affect the activation of platelets and coagulation pathway containers depending on their surface qualities. Importantly, this could produce variability of coagulation results obtained with thrombelastographical analysis. We assessed the effects of blood storage on thrombelastograph, TEG, variables using polypropylene and polycarbonate containers. An in vitro experiment was performed, with eight volunteers in each limb. Fresh whole blood was stored in polypropylene or polycarbonate tubes prior to TEGanalysis, to assess the role of these plastics in the TEG results obtained. The polycarbonate tubes displayed slower onset of coagulation and greater variability of data for all four basic TEG variables (r-time, k-time, alpha-angle and maximum amplitude, P < 0.05). Polycarbonate results fell outside manufacturer reference ranges. It is likely that this is due to the altered surface properties and charge effects of the containers affecting proteins and platelets differently. Caution should be used in choosing which containers are used for storage of fresh blood prior to coagulation assessment, as variable results will follow where different types of plastic containers are employed.

Optical instrument for measurement of vaginal coating thickness by drug delivery formulations

An optical device has been developed for imaging the human vaginal epithelial surfaces, and quantitatively measuring distributions of coating thickness of drug delivery formulations—such as gels—applied for prophylaxis, contraception or therapy. The device consists of a rigid endoscope contained within a 27-mm-diam hollow, polished-transparent polycarbonate tube (150mm long) with a hemispherical cap. Illumination is from a xenon arc. The device is inserted into, and remains stationary within the vagina. A custom gearing mechanism moves the endoscope relative to the tube, so that it views epithelial surfaces immediately apposing its outer surface (i.e., 150mm long by 360° azimuthal angle). Thus, with the tube fixed relative to the vagina, the endoscope sites local regions at distinct and measurable locations that span the vaginal epithelium. The returning light path is split between a video camera and photomultiplier. Excitation and emission filters in the light path enable measurement of fluorescence of the sited region. Thus, the instrument captures video images simultaneously with photometric measurement of fluorescence of each video field [∼10mm diameter; formulations are labeled with 0.1%w∕w United States Pharmacoepia (USP) injectable sodium fluorescein]. Position, time and fluorescence measurements are continuously displayed (on video) and recorded (to a computer database). The photomultiplier output is digitized to quantify fluorescence of the endoscope field of view. Quantification of the thickness of formulation coating of a surface sited by the device is achieved due to the linear relationship between thickness and fluorescence intensity for biologically relevant thin layers (of the order of 0.5mm). Summary measures of coating have been developed, focusing upon extent, location and uniformity. The device has begun to be applied in human studies of model formulations for prophylaxis against infection with HIV and other sexually transmitted pathogens.

Diamondlike carbon film deposition on a polycarbonate-tube inner wall using a cylindrical electrode with radio frequency glow discharge plasma

Radio frequency (rf) plasma chemical vapor deposition (CVD) process is very useful for film deposition. However, common rf plasma CVD techniques using planar electrodes make it difficult to apply to three-dimensional insulator structures. In this study, to deposit diamondlike carbon (DLC) films on a polycarbonate-tube inner wall (ϕ 11mm, length 100mm), we have developed the cylindrical electrode plasma process. This process could be adapted to cylindrical substrates such as polymeric tubes. In investigating the availability of this process, under helium (He) gas pressures (50, 100, and 150Pa), the plasma states of the rf power at 30W were measured using a double-probe method. The He plasma was generated bright as a stable, hollow cathode discharge inside the polycarbonate tube. As a result, the cylindrical electrode process was expected to have applications for cylindrical materials such as polymeric tubes. In actual deposition of DLC film (CH4 gas at 10Pa, rf power at 30W, and deposition time at 10min), the DLC film was deposited completely on the polycarbonate-tube inner wall. The distribution of the film thickness was 300–350nm, and the structures of the DLC film were uniform. It was observed that the DLC film was deposited uniformly. The cylindrical electrode process is expected to apply to three-dimensional insulator structures such as polymeric tubes.

Leaching of bisphenol A (BPA) to seawater from polycarbonate plastic and its degradation by reactive oxygen species

In this study, (1) change in the concentration of bisphenol A (BPA) leached from polycarbonate (PC) tube to control water (BPA free), seawater and river water at 20 and 37 °C as a function of time, (2) the fate of BPA caused by addition of H 2O 2 and Fe 3+ to seawater containing BPA leached from PC tube were assessed. BPA leached from PC tube to all water samples increased with the ascendant of temperature and with the passage of time. The BPA leaching velocity in seawater was the fastest in three samples (11 ng/day for seawater, 4.8 ng/day for river water 0.8 ng/day for control water at 37 °C). BPA leaching velocity from PC tube was significantly high at pH 8 (50 mM Na 2HPO 4) and increased dose-dependently. There was no difference in the velocity of BPA among the 50 mM phosphate-buffers at pH 6.5, 7.0 and 7.5. BPA was leached three times higher by addition of Na + than K +. However, the higher the K + concentration, the larger the BPA leached from PC tube. Na + mixed with PO 4 − was effective on BPA leaching from PC tube, but not with SO 4 − or Cl −. The results suggested that BPA leaching from PC tube would be attributed to the concentration of bibasic phosphate such as Na 2HPO 4 and K 2HPO 4 in water samples. BPA was degraded in both control water and seawater in the presence of radical oxygen species, but the degradation rate was lower in seawater than in control water, suggesting that anti-oxidative system exists in seawater. Neo-synthesized substance in both control water and seawater in the presence of reactive oxygen species was identified as BPA-quinone by LC–MS.