1,869 research outputs found

    In-plant testing of membranes to treat electroplating wastewater

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    This is the final report submitted for the work performed under the NASA Cooperative Agreement NCC3-301 for the project entitled 'In-Plant Testing of Membranes To Treat Electroplating Waste water'. The main objective of the research project was to determine if the crosslinked polyacrylic acid salt films developed by NASA scientists could be used for heavy metal removal from the wastewater generated by the metals-finishing or electroplating industry. A variety of tasks identified in the original proposal were completed. These included: (1) analysis of our industrial partner Aetna Plating's zinc electroplating process and its wastewater treatment needs for zinc removal; (2) design and construction of a laboratory-scale unit to continuously supply and remove the ion exchange films from the zinc wastewater; (3) performance of a series of runs on such a unit to determine its operating characteristics; and (4) design of a prototype unit for use at the industrial site. In addition, there were a number of tasks that had not been identified in the original proposal but were later judged to be necessary for the successful completion of the project. These were: (1) batch equilibrium and kinetic experiments with analysis of the experimental results to accurately determine the equilibrium and kinetic parameters for the ion exchange films; (2 ) simulation studies for proper design of the prototype unit; and (3) preliminary runs to exchange the films from H form to Calcium form

    Diffusivities of n-Alkanes in Silicalite By Steady-State Single-Crystal Membrane Technique

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    A novel experimental technique that measures the diffusive flux through a single-crystal membrane (SCM) was developed and tested. Unlike all other macroscopic techniques that depend on a transient response, SCM is used under steady-state conditions, which results in a wide range of applicability from 10−2 to 10−11 cm2/s. Phenomenological equations for the steady-state data analysis were developed. The variation of driving force over the diffusion path is included in the model. As required by thermodynamics, the micropore concentration is given as a function of surface-excess amount adsorbed and gas density. The membrane configuration measures diffusivity in only one crystallographic direction. The micropore difusivities of C1 to C10 normal alkanes through silicalite crystal in the z-direction were measured at 30, 50 and 70°C. The activation energies for micropore diffusion are also reported. The data agree excellently with the other two studies that measure directional diffusivities. Diffusion and adsorption of hexane and heptane in silicalite display structural heterogeneity induced by the comparable lengths of molecules and silicalite channels rather than diameter of molecule vis-à-vis pore diameter

    Antimicrobial Activity of Flavonoids against Extended-Spectrum &#946-Lactamase (ES&#946L)-Producing Klebsiella pneumoniae

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    Purpose: In the present study, six flavonoids (5,7-dimethoxyflavanone-4'-O-&#946-D-glucopyranoside, 5,7- dimethoxyflavanone-4'-O-[2''-O-(5'''-O-trans-cinnamoyl)-&#946-D-apiofuranosyl]-&#946-D-glucopyranoside, naringenin-7-O-&#946-D-glucopyranoside, 5,7,3'-trihydroxy-flavanone-4'-O-&#946-D-glucopyranoside, rutin, and nicotiflorin) isolated from Galium fissurense, Viscum album ssp. album and Cirsium hypoleucum were screened against extended-spectrum &#946-lactamase producing multidrug-resistant (trimetoprimesulphametoxazole, sulbactam-ampicillin, clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime, tobramicin, gentamicin, ofloxacin, ciprofloxacin) bacteria Klebsiella pneumoniae (ES&#946Ls). Methods: We performed susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) and used an inhibition endpoint for determination of the minimum inhibition concentrations (MICs). Results: All the flavonoids showed in vitro antimicrobial activity against all the isolated strains of K. pneumoniae similar to the control antibacterial (ofloxacin) at the concentrations of 32 - 64 μg ml-l; another control, ampicillin, had no activity. Since, ES&#946L-producing strains are known to be resistant to all &#946-lactam antibiotics, our results fall notably within the concentration range for antimicrobial activity. Conclusion: To the best of our knowledge, this is the first report of the study of the activity of these flavonoids against (ES&#946L)-producing K. pneumoniae and may throw light to the low-toxicity of flavonoids, and their potentials for developing therapies for infections caused by ES&#946L-producing bacteria in the future. Further work is under investigation to identify their precise antibacterial mechanism. Keywords: Antimicrobial activity, ES&#946Ls, Flavonoids, Klebsiella pneumoniae, Ofloxacin, Ampicillin.Tropical Journal of Pharmaceutical Research Vol. 7(4) 2008: pp. 1151-115

    Evaluation of the anatomical measurements of the temporomandibular joint by cone-beam computed tomography

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    Background: To examine the detailed anatomy of the normal temporomandibular joint (TMJ) in a large series of patients divided into different age groups.  Materials and methods: Cone-beam computed tomography images of 100 patients included in the study. Morphometric analysis regarding mandibular con- dyle and mandibular fossa, articular tubercle and the zygomatic arch was done. The volumetric and surface measurements of mandibular condyles (total tissue volume [TV], total bone volume [BV], bone surface area [BS] and percentage of bony tissue of the mandibular condyle [BV/TV]) were also measured.  Results: Statistical analysis was performed and statistically significant differences according to the side of the joint, sex, and age groups were reported. Additionally, correlations between aging and all of these parameters were also determined.  Conclusions: TV, BV, BS and BV/TV parameters according to side, age, and sex groups were defined for normal TMJ which may help to understand the onset and progress of TMJ disorders.

    Morphometric analysis of vidian canal and its relations with surrounding anatomic structures by using cone-beam computed tomography

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    Background: We identified the vidian canal (VC) in a Turkish subpopulation on cone-beam computed tomography (CBCT) images and explored its anatomic relationships; the canal serves as an anatomic pathway during endonasal surgical approaches. Materials and methods: Coronal and axial CBCT images of 100 patients (50 males and 50 females) were evaluated (slice thickness and interval, 0.5 mm). We measured the length of the VC length, extent of VC pneumatisation into the sphenoid sinus, position of the VC relative to the medial pterygopalatine plate (MPP), pterygopalatine fossa (PPF) depth, and VC-VC, VC-MPP, and VC-foramen rotundum (FR) distances, the angle between the posterior end of the middle turbinate and the lateral part of the VC anterior opening, and the angle between the VC and the palatovaginal canal. Results: The mean VC length was 13.09 ± 2.07 and 13.01 ± 2.12 mm on the right and left sides, respectively. Relative to the MPP, the VC was located medially in 54.5% of patients, on the same level in 36%, and laterally in 9.5%. Pneumatisation was of grade I in 24% of patients, grade II in 33%, grade III in 23.5%, and grade IV in 19.5%. The VC-FR and VC-MPP distances were significantly greater on the left side. The angle between the posterior end of the middle turbinate and the lateral part of the anterior VC opening was significantly greater on the right side. The VC-VC distance was significantly greater when the VC lay lateral to the MPP. Conclusions: Anatomic characteristics of the VC on CBCT images unique to Turkish populations should be kept in mind during surgery

    Three-dimensional volumetric analysis of the maxillary sinus: a cone-beam computed tomography study

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    Background: This study aimed to determine the volumetric size of the maxillary sinus and investigate the effect of gender and age on maxillary sinus volume (MSV) using cone-beam computed tomography (CBCT) images in a Turkish subpopulation. Materials and methods: This retrospective volumetric CBCT study was carried out on 133 individuals (84 females, 49 males) between 8 and 51 years old. MSV was measured using the MIMICS 21.0 software (Materialise HQ Technologielaan, Leuven, Belgium). All statistical analyses were performed using the SPSS 21.0 (SPSS, Chicago, IL, USA) software. Mean and standard deviation of both maxillary sinuses measurements were calculated and compared to gender and age. P values < 0.05 were considered to indicate statistical significance. Results: Mean volume of the right maxillary sinus was 13.173 cm3, while for the left was 13.194 cm3. There was no significant difference between right and left maxillary sinus volumes (p > 0.05). There was no significant correlation between MSV and age (p > 0.05). It was found that MSV did not change according to gender (p > 0.05). Conclusions: Right and left maxillary sinus volumes were not different from each other. Gender and age were not found to be related to maxillary sinus volume

    Estimating the gas hydrate recovery prospects in the western Black Sea basin based on the 3D multiphase flow of fluid and gas components within highly permeable paleo-channel-levee systems

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    Gas hydrate deposits are abundant in the Black Sea region and confirmed by direct observations as well as geophysical evidence, such as continuous bottom simulating reflectors (BSRs). Although those gas hydrate accumulations have been well-studied for almost two decades, the migration pathways of methane that charge the gas hydrate stability zone (GHSZ) in the region are unknown. The aim of this study is to explore the most probable gas migration scenarios within a three-dimensional finite element grid based on seismic surveys and available basin cross-sections. We have used the commercial software PetroMod TM(Schlumberger) to perform a set of sensitivity studies that narrow the gap between the wide range of sediment properties affecting the multi-phase flow in porous media. The high-resolution model domain focuses on the Danube deep-sea fan and associated buried sandy channel-levee systems whereas the total extension of the model domain covers a larger area of the western Black Sea basin. Such a large model domain allows for investigating biogenic as well as thermogenic methane generation and a permeability driven migration of the free phase of methane on a basin scale to confirm the hypothesis of efficient methane migration into the gas hydrate reservoir layers by horizontal flow along the carrier beds

    Computerized ionospheric tomography with the IRI model

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    Abstract Computerized ionospheric tomography (CIT) is a method to estimate ionospheric electron density distribution by using the global positioning system (GPS) signals recorded by the GPS receivers. Ionospheric electron density is a function of latitude, longitude, height and time. A general approach in CIT is to represent the ionosphere as a linear combination of basis functions. In this study, the model of the ionosphere is obtained from the IRI in latitude and height only. The goal is to determine the best representing basis function from the set of Squeezed Legendre polynomials, truncated Legendre polynomials, Haar Wavelets and singular value decomposition (SVD). The reconstruction algorithms used in this study can be listed as total least squares (TLS), regularized least squares, algebraic reconstruction technique (ART) and a hybrid algorithm where the reconstruction from the TLS algorithm is used as the initial estimate for the ART. The error performance of the reconstruction algorithms are compared with respect to the electron density generated by the IRI-2001 model. In the investigated scenario, the measurements are obtained from the IRI-2001 as the line integral of the electron density profiles, imitating the total electron content estimated from GPS measurements. It has been observed that the minimum error between the reconstructed and model ionospheres depends on both the reconstruction algorithm and the basis functions where the best results have been obtained for the basis functions from the model itself through SVD

    3d transition metal doping of semiconducting boron carbides

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    The introduction metallocenes, in particular ferrocene (Fe(η5-C5H5)2), cobaltocene (Co(η5-C5H5)2), and nickelocene (Ni(η5-C5H5)2), together with the carborane source molecule closo-1,2-dicarbadodecaborane, during plasma enhanced chemical vapor deposition, will result in the transition metal doping of semiconducting boron carbides. Here we report using ferrocene to introduce Fe dop¬ants, and a semiconducting boron-carbide homojunction has been fabricated. The diode characteristics are very similar to those fabricated with Co and Ni doping
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