Ceramic Carrier Research Articles

Nitrification by biomass immobilized in porous carriers

The possibility of using activated sludge immobilized in porous ceramic carriers in nitrification of ammonia present in municipal wastewater was investigated. Three different carriers made the stable filling of three column reactors with internal circulation. The properties of the carriers such as internal structure, size of active surface, and participation of hollow spaces in the carrier volume determined the effect of volumetric organic and nitrogenous loading on the loading of nitrogen oxidized. Key words: immobilized activated sludge, porous ceramic carriers, municipal wastewater, nitrification.

Strain range fatigue life assessment of lead‐free solder interconnects subject to temperature cycle loading

PurposeThe aim is to present temperature fatigue model constants for lead‐free tin‐silver‐copper solder derived from test data and demonstrate the validity of the model using published experimental results.Design/methodology/approachTemperature cycle fatigue life data were collected from a controlled set of tests using ceramic leadless chip carriers. Using a regression algorithm, temperature cycle fatigue model constants were derived from fatigue life data. The model was then applied to a variety of package formats including ball grid arrays, quad flatpack and thin small outline packages to determine the validity of the model and constants.FindingsThe temperature cycle fatigue life experimental data were found to be in good agreement with the model with the derived model constants for various package types. Using this model, engineers can determine acceleration factors between test and field temperature cycle conditions.Research limitations/implicationsThe technology has been used to ensure inner layer designs with nominal dimensions after the lamination stage. Further, development work should be undertaken to collate measured data from other parts of the PCB manufacturing process and model the material movement around all registration critical processes.Originality/valueThe paper details a temperature cycle fatigue life model and constants that allow engineers to predict field life expectancy and determine the acceleration factor between temperature cycle testing and field use conditions.

Application of the Mixed‐field‐environments concept in lifetime prediction of some ceramic components

AbstractIn lifetime prediction, the effect of a certain use environment on the lifetime is taken into account by using an acceleration factor that is specific to that use environment. The fact that the product may be used in different countries with differing environmental conditions results in a set of acceleration factor values. Prior to this paper, the effect of multiple field environments has been taken into account by using an average value of the acceleration factors obtained for several use environments. As the magnitudes of the acceleration factors (each specific to a certain use environment) vary a lot, the use of the average value has resulted in unrealistic lifetime estimates. The unrealism related to the use of the average value can be avoided when using the mixture‐of‐distributions concept, since the true acceleration factor values, instead of an average value, can then be used. In this paper, the mixture‐of‐distributions concept is applied for the first time to evaluate the effect of multiple use environments (thermal cycling) on the lifetime of a component population. By using this concept, it is possible to evaluate all of the key figures of reliability for the whole population based on the fractions of the component population that are used in multiple, different use environments. This approach can be applied when allocating maintenance and spare parts for a product that is used worldwide. The mixture‐of‐distributions concept in lifetime prediction is demonstrated by analyzing the test results of some ceramic leadless chip carrier components. Acceleration factors in four alternative field environments are estimated by running thermo‐mechanical finite element analysis simulations. The lifetime performance of the whole component population used in certain alternative field environments is then evaluated by applying the mixture‐of‐distributions concept. Copyright © 2006 John Wiley & Sons, Ltd.

7:36 2. A Large-Scale, Level 1, Clinical and Radiographic Analysis of an Optimized rhBMP-2 Formulation as an Autograft Replacement in Posterolateral Lumbar Spine Fusion

BACKGROUND CONTEXT: Acceptance of recombinant human bone morphogenetic protein-2 (rhBMP-2) as a replacement for autogenous iliac crest bone graft (ICBG) has increased, and new surgical applications are being sought. It was observed in earlier pilot studies using a higher dose of rhBMP-2 with a ceramic carrier in patients undergoing posterolateral fusion surgery that rhBMP-2 promotes new bone formation and achieves high rates of fusion without the morbidity associated with ICBG.

A Fine Pitch Bump Bonding Process Compatible With the Manufacture of the Pixel-HPD's for the LHCb RICH Detector

A new approach to photo detection using pixel Hybrid Photon Detectors (pixel-HPD's) has been adopted for the LHCb-RICH detector. These devices use a hybrid pixel detector inside an evacuated photo tube providing high-precision, low noise detection of Cherenkov radiation. The approach takes advantage of modern CMOS technology offering many advantages over more traditional techniques. These advantages include extremely high sensitivity, low noise and fast readout. A major technological challenge was the encapsulation of a hybrid pixel detector inside a photo detector tube. The fabrication of the HPD tube involves packaging of the pixel detector assembly onto a ceramic carrier to form the photo-anode and the subsequent bake out of the pixel anode under vacuum. Both processes involve high temperatures. A fine pitch solder bump-bonding technique, which is compatible with the manufacture of hybrid photo detectors, has been developed. The technology and the tests used for qualifying the new process for pixel-HPD production are described. More than 40 pixel detector assemblies have been produced with almost all showing <1% of missing pixels. A number of assemblies were baked out using temperature cycles identical to those used for pixel-HPD manufacture. None of the assemblies demonstrated any degradation. SEM photos clearly indicate the reliability of the process. 10 pixel-HPD tubes have been produced using this new bump-bonding process and those behave according to expectations. The pixel-HPD is the first of a new generation of photo detector tubes suitable for RICH and other visible photon sensing applications

Sub-surface probe module equipped with the Karlsruhe Micronose KAMINA using a hierarchical LDA for the recognition of volatile soil pollutants

For the integration in an electric hammer driven soil air probe a battery-operated cylindrical EN module was developed on the basis of the Karlsruhe Micronose KAMINA for rapid depth-resolved soil screening. The EN module contains the complete battery-operated electronics and a 3.5 mm × 3 mm KAMINA gradient microarray chip with a single Pt-doped SnO 2-film. In order to achieve high mechanical stability and low power consumption the microarray chip is fixed only with bond wires within the clearance of a ceramic carrier card. Test exposures of the module were carried out with a variety of potential soil pollutants (such as chlorinated, aromatic, aliphatic hydrocarbons in air with 80% r.h.) in order to investigate the KAMINA's gas analytical performance. The detection limits were <1 mg/m 3 for aromatic and aliphatic hydrocarbons, except 10–500 mg/m 3 for chlorinated hydrocarbons at response times <100 s. The gas discrimination power was found appropriate to distinguish between these type of pollutants. A novel hierarchical linear discriminant analysis has been developed for online classification of volatile soil pollution.

Effect of Volumetric Organic Loading on the Nitrogen Removal Rate by Immobilised Activated Sludge

Activated sludge was immobilised in a porous ceramic carrier to create a stationary core of a bio-reactor. Municipal wastewater was treated in this reactor under varied conditions of volumetric organic loading rate (expressed by chemical oxygen demand (COD)) that were the following: 6.5, 8.0, 20.8, 48.8 g COD l&minus1 d−1. The rate constants of ammonification, nitrification and denitrification under aerobic conditions were determined. All rate constants increased with a growth in volumetric loading rate, but the highest loading value of 48.8 g COD l&minus1 d−1 limited the ammonification and nitrification rates.

Biochip-compatible packaging and micro-fluidics for a silicon opto-electronic biosensor

Biochip-compatible packaging for a DNA monolithic opto-electronic biosensor is presented. The packaging involves coated opto-coupler chips, ceramic carriers, plastic fluidic modules, optical alignment, self-aligned under-fill gluing as well as potting encapsulation. All the steps were implemented without denaturing the bio-molecular probes and without degrading the optical quality of the transducers. Such a packaged optical microchip was successfully employed in SNP detection.

A model study based on experiments on toluene removal under high load condition in biofilters

As a control measure for substrate inhibition phenomenon in biofilters caused by toxic gases with high concentration, an appropriate mathematical model is required to calculate gas concentrations at various positions within and outside biofilms. Thus validation of the Deshussess model, Devinny–Hodge model and Luong Model were carried out for high toluene load conditions, and the results were examined for their veracity. Calculated concentrations using the modified Deshussess model, which considers sorption volume of carriers, approximated to measurements. This appears to mean the contribution of porosity in inorganic ceramic carriers to the biological removal of toluene vapor. Since toluene removal capacities for high liquid concentrations, which were calculated using the Luong model, approximated to the measurements, the generality and usefulness of the Luong model in predicting the substrate elimination capacity in biofilters with substrate inhibition appear to be manifested. Simplified Devinny–Hodge model turned out to be not applicable to predicting gas concentration along longitudinal axis of biofilters with high gas load. Various model parameters, needed for modeling studies, including critical toluene load per unit biomass and time, maximum toluene degradation rate, half velocity toluene concentration, and maximum toluene concentration in liquid, above which biodegradation is inhibited, were experimentally determined.

Novel immobilization of titanium dioxide (TiO 2) on the fluidizing carrier and its application to the degradation of azo-dye

A photocatalyst was prepared by attaching TiO 2 powder (diameter, 50 nm) in the sol state to fluidizing spherical ceramic carriers using a silicon binder. A high initial photocatalytic activity and strong attachment was obtained at a sintering temperature of 500 °C. An azo-dye (Orange-G) was used as the test contaminant to examine the photocatalytic effect of the new photocatalyst. The initial pseudo-first order degradation rate constant for Orange-G was 0.11 min −1. However, the photocatalytic activity doubled when boric acid was added to the silicon binder at a B to Si ratio of 106.5%. When sodium ethoxide was added to the silicon binder at a sodium ion to Si ratio of 15.0%, as much as 80% of the initial photocatalytic activity was maintained after the photocatalyst had been agitated at 180 rpm for 300 min. Adding both boric acid at a B/Si ratio of 106.5% and sodium ethoxide at a Na/Si ratio of 15% increased the photocatalytic activity and stability by three and four times, respectively.

Healing of Critically Sized Femoral Defects, Using Genetically Modified Mesenchymal Stem Cells from Human Adipose Tissue

The FDA has approved the clinical use of recombinant bone morphogenetic proteins (BMPs). However, the use of recombinant BMPs in humans has required large doses of the proteins to be effective, which suggests that the delivery method of bone morphogenetic proteins needs to be optimized. Gene therapy is an alternative method to deliver such recombinant proteins, and gene transfer techniques have been tested on a variety of cell types including bone marrow cells, skin fibroblasts, peripheral blood monocytes, and muscle-derived cells. In this study, we sought to determine the ability of BMP-2-producing human adipose-derived mesenchymal stem cells to heal a critically sized femoral defect in a nude rat model. After approval by the human subjects protection committee, human adipose tissue was obtained from healthy donors. The lipoaspirate was processed as previously described (De Ugarte, D.A., et al. Cells Tissues Organs 174, 101, 2003). Cells were grown in culture and infected with a BMP-2-carrying adenovirus. Five million cells were applied to a collagen- ceramic carrier and implanted into femoral defects as previously described (Zuk, P.A., et al. Mol. Biol. 13, 4279, 2002). All animals were killed at 8 weeks. Femora were dissected out and underwent radiographic, histologic, and biomechanical analysis. Eleven of the 12 femora in the group treated with human processed lipoaspirate (HPLA) cells genetically modified to overexpress BMP-2 had healed at 8 weeks. This was assessed by radiographs, by mechanical testing, and by histology. The one femur that did not heal had a subacute infection. All eight of the femora treated with the rhBMP-2-impregnated collagen-ceramic carrier healed. No statistically significant difference was detected between these two groups. Evaluation of the control groups: group II (collagen- ceramic carrier with HPLA cells) and group III (collagen-ceramic carrier alone) showed that none of the femora had healed by 8 weeks. Our results indicate that HPLA cells genetically modified by adenoviral gene transfer to overexpress BMP-2 can induce bone formation in vivo and heal a critically sized femoral defect in an athymic rat. The HPLA cells alone did not induce significant bone formation. However, when combined with an osteoinductive factor these cells may be an effective method for enhancing bone healing and the tissue engineering of bone.

Specific features of the structure of filtering cordierite-containing materials

The use of cordierite for preparation of filtering ceramic materials is discussed. Phase composition and structure of permeable sintered cordierite-containing ceramics are considered. Results of a study of cordierite-based “honeycomb” materials used in the high-temperature catalytic conversion of methane are presented. The newly designed ceramic catalyst carriers are shown to conform with service requirements.

Cultivation of immobilized Dictyostelium discoideum for the production of soluble human Fas ligand.

Dictyostelium discoideum was immobilized by cultivation on inorganic porous matrices consisting of broken pumice or a ceramic catalyst carrier (CeramTec) to produce human soluble Fas ligand (hFasL). These supports were actively colonized by D. discoideum reaching cell (number) densities 10-20 times higher locally than those observed in suspension culture under similar conditions. In repeated batch or continuous operation, hFasL productivities of up to 15-25 microg h(-1) l(-1) pore volume were attained. The immobilized cell densities and hFasL productivities could be kept constant for a long period of time by repeated renewal or continuous feeding of complex or synthetic medium.

Focused ion beam and transmission electron microscopy method for root cause analysis of InP ridge laser devices

To remain competitive in industry, the continual assessment of product reliability is critical. This article discusses the focused ion beam preparation of transmission electron microscopy (TEM) specimens from InP ridge laser devices for observation and analysis of a wide range of microstructural and chemical phenomena (root cause) in reliability-tested lasers. A method is described that enables routine sectioning of ridge lasers mounted ridge up or down and/or beneath solder. The laser devices provided for reliability studies were fully wire bonded on ceramic carriers. Given the geometry, several specimens could be acquired from a single device. Here, it was imperative to thin the metal, dielectric and semiconductor layers in one specimen where the active region of the device was 1 to 3 μm below the metal contact. The structure and morphology of the devices were studied using analytical TEM with energy dispersive x-ray spectroscopy.

Efficacy of sodium hypochlorite disinfectant on the viability and allergenic properties of household mold

Rationale Many fungi colonize indoor environments and produce allergenic proteins that cause adverse health symptoms in sensitive individuals. The effect of sodium hypochlorite (2.4% NaOCl) disinfectant on fungal growth and the presence of allergenic properties was evaluated. Methods Environmental and laboratory isolates of common indoor mold contaminants ( Penicillium, Cladosporium, Mucor, Rhizopus, Stachybotrys, Alternaria, Aspergillus, Helminthosporium, and Trichophyton) were grown to sporulation, purified, dried on sterile ceramic porous and non-porous carriers, and treated with 2.4% NaOCl for up to 10 min. Volunteer's showers were monitored, for 2 weeks to determine the rate of mold regrowth following disinfectant treatment. ELISA tests measured the ability of NaOCl to reduce the allergenic properties of Aspergillus fumigatus following 30 sec, 1 min, and 5 min exposures. Results 2.4% NaOCl reduced total mold counts in home showers by >4 logs after 5 min exposures. In controlled laboratory studies, home mold isolates were reduced by >5 logs following 5 min exposures with 2.4% NaOCl. Test organisms were not culturable in 10 out of 10 trials after 5 and 10 min contact times in non-porous and porous ceramic carriers, respectively. NaOCl treatment reduced A. fumigatus allergen levels by >90% in as little as 30 seconds. Conclusions Low concentrations (2.4%) of NaOCl, common to household disinfectants, are effective at reducing mold from indoor surfaces, to undetectable levels, in both real-time and seeded laboratory studies. In addition, NaOCl effectively fragments the proteins responsible for the allergenic properties of indoor mold.

Bioluminescent bioreporter integrated circuits: potentially small, rugged and inexpensive whole-cell biosensors for remote environmental monitoring.

1. SUMMARYA bioluminescent bioreporter integrated circuit (BBIC) is anovel whole-cell biosensor that combines the environmentalmonitoring capabilities of genetically engineered biolu-minescent micro-organisms (bioreporters) with optical appli-cation-specific integrated circuits. A BBIC device consistsof bioreporters sustained within a micro-environment, theintegrated circuit microluminometer, and a light-tightenclosure. The bioreporter typically contains the luxCDABEreporter genes encoding the enzymes required for biolumin-escence. In the presence of a targeted analyte, a gene(transcriptional) regulatory system induces the expressionof the luxCDABE genes. Analytical benchmark data forexposure of the bioreporter Pseudomonas fluorescens 5RLto salicylate was determined using a flow-through testsystem. The detection limit (after a 45 min exposure) wasca 50 lgl

Mass production of Dictyostelium discoideum in homogeneous and heterogeneous cultivation systems

The social amoeba Dictyostelium discoideum is a promising host for the expression of recombinant proteins requiring post-translational modifications. Limited maximal cell densities and slow growth rates, however, disfavor its application. Little attention has been paid to improve its cultivation. Here, some strategies are described, which allow the attainment of higher cell densities. This can be achieved by cultivation on an improved synthetic medium as well as in immobilized form. Two promising inorganic porous supports are presented—broken pumice and a ceramic catalyst carrier. Cell densities up to 4.5×10 7 ml −1 are obtained during suspension cultivation on the improved synthetic medium. This is about three times as much as can be expected for cultivations on conventional complex media. Cells in the pores of broken pumice and a ceramic support reach up to 15–20 times higher local cell densities compared with cells growing on conventional axenic media in suspension. Thus, the cell density of 3.5×10 8 ml −1 in the ceramic carrier (CeramTec ®) is the highest cell density for D. discoideum observed so far in cultivation systems. The immobilized cell density could be maintained for a long period of time by either repeated medium replacement or continuous cultivation. To minimize the external volume of the medium a trickle bed reactor was operated continuously.

Preparation and characteristics of high performance paper containing titanium dioxide photocatalyst supported on inorganic fiber matrix

A novel paper-based material containing titanium dioxide (TiO 2) photocatalyst was successfully prepared by a papermaking technique with the internal addition of inorganic fibers on which TiO 2 particles were supported. Photodegradation performance of acetaldehyde gas, an indoor pollutant, and the durability of the TiO 2-containing papers were investigated under UV irradiation. Ceramic fiber suspension and polydiallyldimethylammonium chloride as a cationic flocculant were mixed, followed by the addition of TiO 2 suspension and anionic polyacrylamide. Subsequently, the inorganic mixture was poured into a pulp suspension, and TiO 2 handsheets then prepared by a papermaking method. The tensile strength of TiO 2-containing paper without a ceramic carrier decreased by more than 30% after 240-h UV irradiation (2 mW/cm 2), although the strength of the TiO 2 sheet with ceramic fibers remained reasonably stable. The efficiency of acetaldehyde decomposition by the TiO 2 paper containing an inorganic carrier was nearly equal to that of the carrier-free TiO 2 paper. Scanning electron microscopic observation suggested that most TiO 2 particles were predominantly supported on the inorganic fiber matrix, and were mostly out of contact with organic pulp fibers. The TiO 2 paper with an inorganic carrier demonstrated both excellent photocatalytic performance and durability, which before had been mutually incompatible for organic materials containing TiO 2 photocatalyst. The two-stage mixing procedure for TiO 2 sheet-making is promising for the simple manufacture of high performance paper with photocatalytic ability.

Biodegradation of 2,4-dichlorophenol in an air-lift honeycomb-like ceramic reactor

A novel air-lift bioreactor, with a honeycomb-like ceramic column packed in the inner draft tube as the carrier for immobilization of microbial cells, was developed in this laboratory. A microorganism, identified as Achromobacter sp. and capable of degrading 2,4-dichlorophenol (2,4-DCP), was immobilized in the ceramic carrier and used for biodegradation of 2,4-DCP. Semi-continuous biodegradation of 2,4-DCP as a single substrate and in the presence of phenol as co-substrate was investigated. The results showed that when 2,4-DCP occurs alone, its biodegradation rate increased gradually from Run 1 to Run 6 and the degradation process could be described with zero-order kinetics model. When phenol was used as co-substrate, the existence of phenol could inhibit the biodegradation of 2,4-DCP and the biodegradation rate of 2,4-DCP decreased gradually. However, the biodegradation of phenol increased with the increase of run number of the batch experiments. In addition, continuous degradation of 2,4-DCP was also investigated. The results indicated that 2,4-DCP at the concentration ranged from 6.86 to 102.38 mg l −1 could be degraded at a dilution rate of 0.16 h −1 and the removal percentage ranged between 84 and 100%. The effect of interruption of 2,4-DCP supply to the bioreactor on the degradation ability of microbial cells was investigated by replacing 2,4-DCP with sodium acetate as the sole carbon source for 12 days. Intermission of 2,4-DCP supply did not cause the loss of chlorophenol-degrading ability.

Simple carrier matrix modifications can enhance delivery of recombinant human bone morphogenetic protein-2 for posterolateral spine fusion.

A nonhuman primate lumbar intertransverse process arthrodesis model was used to evaluate modifications to a plain collagen sponge to deliver recombinant human bone morphogenetic protein-2 (rhBMP-2). To evaluate the feasibility of enhancing the delivery of rhBMP-2 with the established collagen sponge carrier by adding biphasic ceramic phosphate (BCP) granules (15% hydroxyapatite, 85% tricalcium phosphate) or allograft chips to provide compression resistance for posterolateral spine arthrodesis. Recombinant human bone morphogenetic protein-2 was successfully delivered with a resorbable collagen sponge in a rabbit intertransverse process fusion model. Success in nonhuman primates required a higher dose (6-9 mg) of rhBMP-2 and a more compression-resistant matrix (ceramic) than plain collagen. The limitation of the ceramic carrier was its radiopacity, which made radiographic detection of new bone formation difficult. Nine adult rhesus monkeys underwent bilateral posterolateral intertransverse process arthrodesis at L4-L5. The animals were divided into three groups (n = 3 each) based on the graft material implanted: 1) autogenous iliac crest bone (5 cm3/side); 2) collagen sponge and 15:85 BCP granules loaded with rhBMP-2 (3 mg/side); and, 3) collagen sponge and allograft chips loaded with rhBMP-2 (3 mg/side). The monkeys were killed 24 weeks after surgery. Inspection, manual palpation, radiography, computed tomographic scans, and histology were used to assess fusion. All six monkeys with rhBMP-2 delivered in the collagen/15:85 BCP carrier and the collagen/allograft chips carrier achieved solid spine fusions, whereas only one of three animals fused with autogenous bone graft. Histologic analysis of the bone induced by rhBMP-2 showed normal trabecular bone and bone marrow elements. The addition of either 15:85 BCP granules or allograft bone chips to the existing resorbable collagen sponge matrix enhanced delivery of rhBMP-2 in the posterolateral spine. The combination matrices were more compression resistant and had improved radiographic resorption properties that permitted easy radiographic visualization of new bone. In addition, a lower dose of rhBMP-2 (3 mg/side) was successful compared with the dose previously used with the plain collagen sponge (6 mg/side).