ELM mitigation studies in JET and implications for ITER

NASA Astrophysics Data System (ADS)

de La Luna, Elena

2009-11-01

Type I edge localized modes (ELMs) remain a serious concern for ITER because of the high transient heat and particle flux that can lead to rapid erosion of the divertor plates. This has stimulated worldwide research on exploration of different methods to avoid or at least mitigate the ELM energy loss while maintaining adequate confinement. ITER will require reliable ELM control over a wide range of operating conditions, including changes in the edge safety factor, therefore a suite of different techniques is highly desirable. In JET several techniques have been demonstrated for control the frequency and size of type I ELMs, including resonant perturbations of the edge magnetic field (RMP), ELM magnetic triggering by fast vertical movement of the plasma column (``vertical kicks'') and ELM pacing using pellet injection. In this paper we present results from recent dedicated experiments in JET focusing on integrating the different ELM mitigation methods into similar plasma scenarios. Plasma parameter scans provide comparison of the performance of the different techniques in terms of both the reduction in ELM size and on the impact of each control method on plasma confinement. The compatibility of different ELM mitigation schemes has also been investigated. The plasma response to RMP and vertical kicks during the ELM mitigation phase shares common features: the reduction in ELM size (up to a factor of 3) is accompanied by a reduction in pedestal pressure (mainly due to a loss of density) with only minor (< 10%) reduction of the stored energy. Interestingly, it has been found that the combined application of RMP and kicks leads to a reduction of the threshold perturbation level (vertical displacement in the case of the kicks) necessary for the ELM mitigation to occur. The implication of these results for ITER will be discussed.

Feasibility study on the design of a probe for rectal cancer detection

NASA Technical Reports Server (NTRS)

Anselm, V. J.; Frazer, R. E.; Lecroisset, D. H.; Roseboro, J. A.; Smokler, M. I.

1977-01-01

Rectal examination techniques are considered in terms of detection capability, patient acceptance, and cost reduction. A review of existing clinical techniques are considered in terms of detection capability, patient acceptance, and cost reduction. A review of existing clinical techniques and of relevant aerospace technology included evaluation of the applicability of visual, thermal, ultrasound, and radioisotope modalities of examination. The desired improvements can be obtained by redesigning the proctosigmoidoscope to have reduced size, additional visibility, and the capability of readily providing a color photograph of the entire rectosigmoid mucosa in a single composite view.

Parallelized modelling and solution scheme for hierarchically scaled simulations

NASA Technical Reports Server (NTRS)

Padovan, Joe

1995-01-01

This two-part paper presents the results of a benchmarked analytical-numerical investigation into the operational characteristics of a unified parallel processing strategy for implicit fluid mechanics formulations. This hierarchical poly tree (HPT) strategy is based on multilevel substructural decomposition. The Tree morphology is chosen to minimize memory, communications and computational effort. The methodology is general enough to apply to existing finite difference (FD), finite element (FEM), finite volume (FV) or spectral element (SE) based computer programs without an extensive rewrite of code. In addition to finding large reductions in memory, communications, and computational effort associated with a parallel computing environment, substantial reductions are generated in the sequential mode of application. Such improvements grow with increasing problem size. Along with a theoretical development of general 2-D and 3-D HPT, several techniques for expanding the problem size that the current generation of computers are capable of solving, are presented and discussed. Among these techniques are several interpolative reduction methods. It was found that by combining several of these techniques that a relatively small interpolative reduction resulted in substantial performance gains. Several other unique features/benefits are discussed in this paper. Along with Part 1's theoretical development, Part 2 presents a numerical approach to the HPT along with four prototype CFD applications. These demonstrate the potential of the HPT strategy.

Novel Application of Density Estimation Techniques in Muon Ionization Cooling Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohayai, Tanaz Angelina; Snopok, Pavel; Neuffer, David

The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate muon beam ionization cooling for the first time and constitutes a key part of the R&D towards a future neutrino factory or muon collider. Beam cooling reduces the size of the phase space volume occupied by the beam. Non-parametric density estimation techniques allow very precise calculation of the muon beam phase-space density and its increase as a result of cooling. These density estimation techniques are investigated in this paper and applied in order to estimate the reduction in muon beam size in MICE under various conditions.

Nipple Reduction With the Chullo-Hat Technique.

PubMed

Sim, Hyung-Bo; Sun, Sang-Hoon

2015-08-01

Although various techniques of nipple reduction have been described in the literature, many are difficult to design or have unreliable outcomes. For men, as well as women who do not plan to breastfeed, it is not necessary to apply a complicated technique that protects the lactiferous ducts. The authors introduce a simple technique for nipple reduction that has achieved consistent, reproducible results. The desired nipple length is marked, and a chullo-hat excision pattern is drawn. After infiltration of a local anesthetic solution around the nipple, excision of the excess nipple tissue is performed, comprising 2 triangular flaps. The remaining 2 pillars are approximated with 5-0 Nylon simple interrupted sutures. However, the wound is not completely closed in the central area of the nipple, which promotes the drainage of discharge. Fifty-three women (106 nipples) underwent this surgery between December 2009 and December 2013. The follow-up period ranged from 6 months to 2 years (mean, 10 months). No major complications occurred, and the scars were very inconspicuous. The postoperative appearance of nipples was consistently similar in size and shape. This simple technique was safe and effective in nipples of different sizes. The results were reliable and consistent with expectations. Although this study included only women, the authors believe that outcomes would be successful in men as well. 4 Therapeutic. © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Particle size effect of redox reactions for Co species supported on silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chotiwan, Siwaruk; Tomiga, Hiroki; Katagiri, Masaki

Conversions of chemical states during redox reactions of two silica-supported Co catalysts, which were prepared by the impregnation method, were evaluated by using an in situ XAFS technique. The addition of citric acid into the precursor solution led to the formation on silica of more homogeneous and smaller Co particles, with an average diameter of 4 nm. The supported Co{sub 3}O{sub 4} species were reduced to metallic Co via the divalent CoO species during a temperature-programmed reduction process. The reduced Co species were quantitatively oxidized with a temperature-programmed oxidation process. The higher observed reduction temperature of the smaller CoO particlesmore » and the lower observed oxidation temperature of the smaller metallic Co particles were induced by the higher dispersion of the Co oxide species, which apparently led to a stronger interaction with supporting silica. The redox temperature between CoO and Co{sub 3}O{sub 4} was found to be independent of the particle size. - Graphical abstract: Chemical state conversions of SiO{sub 2}-supported Co species and the particle size effect have been analyzed by means of in situ XAFS technique. The small CoO particles have endurance against the reduction and exist in a wide temperature range. Display Omitted - Highlights: • The conversions of the chemical state of supported Co species during redox reaction are evaluated. • In operando XAFS technique were applied to measure redox properties of small Co particles. • A small particle size affects to the redox temperatures of cobalt catalysts.« less

Effect of dust size distribution on ion-acoustic solitons in dusty plasmas with different dust grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Dong-Ning; Yang, Yang; Yan, Qiang

Theoretical studies are carried out for ion acoustic solitons in multicomponent nonuniform plasma considering the dust size distribution. The Korteweg−de Vries equation for ion acoustic solitons is given by using the reductive perturbation technique. Two special dust size distributions are considered. The dependences of the width and amplitude of solitons on dust size parameters are shown. It is found that the properties of a solitary wave depend on the shape of the size distribution function of dust grains.

Posterior dental size reduction in hominids: the Atapuerca evidence.

PubMed

Bermúdez de Castro, J M; Nicolas, M E

1995-04-01

In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984-1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution.

Improved magnetic and electrical properties of Cu doped Fe-Ni invar alloys synthesized by chemical reduction technique

NASA Astrophysics Data System (ADS)

Ahmad, Sajjad; Ziya, Amer Bashir; Ashiq, Muhammad Naeem; Ibrahim, Ather; Atiq, Shabbar; Ahmad, Naseeb; Shakeel, Muhammad; Khan, Muhammad Azhar

2016-12-01

Fe-Ni-Cu invar alloys of various compositions (Fe65Ni35-xCux, x=0, 0.2, 0.6, 1, 1.4 and 1.8) were synthesized via chemical reduction route. These alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) techniques. The XRD analysis revealed the formation of face centered cubic (fcc) structure. The lattice parameter and the crystallite size of the investigated alloys were calculated and the line broadening indicated the nano-crystallites size of alloy powder. The particle size was estimated from SEM and it decreases by the incorporation of Cu and found to be in the range of 24-40 nm. The addition of Cu in these alloys appreciably enhances the saturation magnetization and it increases from 99 to 123 emu/g. Electrical conductivity has been improved with Cu addition. The thermal conductivity was calculated using the Wiedemann-Franz law.

Development and application of a technique for reducing airframe finite element models for dynamics analysis

NASA Technical Reports Server (NTRS)

Hashemi-Kia, Mostafa; Toossi, Mostafa

1990-01-01

A computational procedure for the reduction of large finite element models was developed. This procedure is used to obtain a significantly reduced model while retaining the essential global dynamic characteristics of the full-size model. This reduction procedure is applied to the airframe finite element model of AH-64A Attack Helicopter. The resulting reduced model is then validated by application to a vibration reduction study.

Post-processing of metal matrix composites by friction stir processing

NASA Astrophysics Data System (ADS)

Sharma, Vipin; Singla, Yogesh; Gupta, Yashpal; Raghuwanshi, Jitendra

2018-05-01

In metal matrix composites non-uniform distribution of reinforcement particles resulted in adverse affect on the mechanical properties. It is of great interest to explore post-processing techniques that can eliminate particle distribution heterogeneity. Friction stir processing is a relatively newer technique used for post-processing of metal matrix composites to improve homogeneity in particles distribution. In friction stir processing, synergistic effect of stirring, extrusion and forging resulted in refinement of grains, reduction of reinforcement particles size, uniformity in particles distribution, reduction in microstructural heterogeneity and elimination of defects.

Solid State Reduction of MoO3 with Carbon via Mechanical Alloying to Synthesize Nano-Crystaline MoO2

NASA Astrophysics Data System (ADS)

Saghafi, M.; Ataie, A.; Heshmati-Manesh, S.

In this research, effect of milling time on solid state reduction of MoO3 with carbon has been investigated. It was found that mechanical activation of a mixture of MoO3 and carbon at ambient temperature by high energy ball milling was not able to reduce MoO3 to metallic molybdenum. MoO3 was converted to MoO2 at the first stage of reduction and peaks of the latter phase in X-ray diffraction patterns were detected when the milling time exceeded from 50 hours. The main effect of increased milling time at this stage was decreasing of MoO3 peak intensities and significant peak broadening due to decrease in size of crystallites. After prolonged milling, MoO3 was fully reduced to nano-crystalline MoO2 and its mean crystallite size was calculated using Williamson-Hall technique and found to be 17.5 nm. Thermodynamic investigations also confirm the possibility of reduction of MoO3 to MoO2 during the milling operation at room temperature. But, further reduction to metallic molybdenum requires thermal activation at higher temperature near 1100 K. XRD and SEM techniques were employed to evaluate the powder particles characteristics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arbique, G; Anderson, J; Guild, J

Purpose: The National Lung Screening Trial mandated manual low dose CT technique factors, where up to a doubling of radiation output could be used over a regular to large patient size range. Recent guidance from the AAPM and ACR for lung cancer CT screening recommends radiation output adjustment for patient size either through AEC or a manual technique chart. This study evaluated the use of AEC for output control and dose reduction. Methods: The study was performed on a multidetector helical CT scanner (Aquillion ONE, Toshiba Medical) equipped with iterative reconstruction (ADIR-3D), AEC was adjusted with a standard deviation (SD)more » image quality noise index. The protocol SD parameter was incrementally increased to reduce patient population dose while image quality was evaluated by radiologist readers scoring the clinical utility of images on a Likert scale. Results: Plots of effective dose vs. body size (water cylinder diameter reported by the scanner) demonstrate monotonic increase in patient dose with increasing patient size. At the initial SD setting of 19 the average CTDIvol for a standard size patient was ∼ 2.0 mGy (1.2 mSv effective dose). This was reduced to ∼1.0 mGy (0.5 mSv) at an SD of 25 with no noticeable reduction in clinical utility of images as demonstrated by Likert scoring. Plots of effective patient diameter and BMI vs body size indicate that these metrics could also be used for manual technique charts. Conclusion: AEC offered consistent and reliable control of radiation output in this study. Dose for a standard size patient was reduced to one-third of the 3 mGy CTDIvol limit required for ACR accreditation of lung cancer CT screening. Gary Arbique: Research Grant, Toshiba America Medical Systems; Cecelia Brewington: Research Grant, Toshiba America Medical Systems; Di Zhang: Employee, Toshiba America Medical Systems.« less

Particle size reduction of Si3N4 with Si3N4 milling hardware

NASA Technical Reports Server (NTRS)

Herbell, T. P.; Freedman, M. R.; Kiser, J. D.

1986-01-01

The grinding of Si3N4 powder using reaction bonded Si3N4 attrition, vibratory, and ball mills with Si3N4 media was examined. The rate of particle size reduction and the change in the chemical composition of the powder were determined in order to compare the grinding efficiency and the increase in impurity content resulting from mill and media wear for each technique. Attrition and vibratory milling exhibited rates of specific surface area increase that were approximately eight times that observed in ball milling. Vibratory milling introduced the greatest impurity pickup.

Drug particle size influence on enteric beads produced by a droplet extrusion/precipitation method.

PubMed

Cerdeira, A M; Gouveia, L F; Goucha, P; Almeida, A J

2000-01-01

The influence of drug particle size on the production of enteric beads by a polymer precipitation technique was investigated. Drug particle dimensions are known to play an important role in most microencapsulation techniques. Bead morphology was greatly influenced by drug particle size, and spherical shaped beads could only be obtained after size reduction of nimesulide crystals. This is confirmed by the angle of repose measurements, which show a significant decrease in theta values when beads are formulated with smaller drug particles. Furthermore, results show that drug encapsulation efficiency and in vitro drug release rates are also greatly dependent on both drug particle size and drug/polymer ratio in the initial suspension. Preparations containing 10.2 microm drug particles show a two-fold increase in the release rates when compared to those prepared with 40 microm particles.

Assessing the response to targeted therapies in renal cell carcinoma: technical insights and practical considerations.

PubMed

Bex, Axel; Fournier, Laure; Lassau, Nathalie; Mulders, Peter; Nathan, Paul; Oyen, Wim J G; Powles, Thomas

2014-04-01

The introduction of targeted agents for the treatment of renal cell carcinoma (RCC) has resulted in new challenges for assessing response to therapy, and conventional response criteria using computed tomography (CT) are limited. It is widely recognised that targeted therapies may lead to significant necrosis without significant reduction in tumour size. In addition, the vascular effects of antiangiogenic therapy may occur long before there is any reduction in tumour size. To perform a systematic review of conventional and novel imaging methods for the assessment of response to targeted agents in RCC and to discuss their use from a clinical perspective. Relevant databases covering the period January 2006 to April 2013 were searched for studies reporting on the use of anatomic and functional imaging techniques to predict response to targeted therapy in RCC. Inclusion criteria were randomised trials, nonrandomised controlled studies, retrospective case series, and cohort studies. Reviews, animal and preclinical studies, case reports, and commentaries were excluded. A narrative synthesis of the evidence is presented. A total of 331 abstracts and 76 full-text articles were assessed; 34 studies met the inclusion criteria. Current methods of response assessment in RCC include anatomic methods--based on various criteria including Choi, size and attenuation CT, and morphology, attenuation, size, and structure--and functional techniques including dynamic contrast-enhanced (DCE) CT, DCE-magnetic resonance imaging, DCE-ultrasonography, positron emission tomography, and approaches utilising radiolabelled monoclonal antibodies. Functional imaging techniques are promising surrogate biomarkers of response in RCC and may be more appropriate than anatomic CT-based methods. By enabling quantification of tumour vascularisation, functional techniques can directly and rapidly detect the biologic effects of antiangiogenic therapies compared with the indirect detection of belated effects on tumour size by anatomic methods. However, larger prospective studies are needed to validate early results and standardise techniques. Copyright © 2013 European Association of Urology. All rights reserved.

Liquigroud technique: a new concept for enhancing dissolution rate of glibenclamide by combination of liquisolid and co-grinding technologies.

PubMed

Azharshekoufeh, Leila; Shokri, Javad; Barzegar-Jalali, Mohammad; Javadzadeh, Yousef

2017-01-01

Introduction: The potential of combining liquisolid and co-grinding technologies (liquiground technique) was investigated to improve the dissolution rate of a water-insoluble agent (glibenclamide) with formulation-dependent bioavailability. Methods: To this end, different formulations of liquisolid tablets with a wide variety of non-volatile solvents contained varied ratios of drug: solvent and dissimilar carriers were prepared, and then their release profiles were evaluated. Furthermore, the effect of size reduction by ball milling on the dissolution behavior of glibenclamide from liquisolid tablets was investigated. Any interaction between the drug and the excipient or crystallinity changes during formulation procedure was also examined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results: The present study revealed that classic liquisolid technique did not significantly affect the drug dissolution profile as compared to the conventional tablets. Size reduction obtained by co-grinding of liquid medication was more effective than the implementation of liquisolid technique in enhancing the dissolution rate of glibenclamide. The XRD and DSC data displayed no formation of complex or any crystallinity changes in both formulations. Conclusion: An enhanced dissolution rate of glibenclamide is achievable through the combination of liquisolid and co-grinding technologies.

Size-dependent electrocatalytic activity of gold nanoparticles on HOPG and highly boron-doped diamond surfaces.

PubMed

Brülle, Tine; Ju, Wenbo; Niedermayr, Philipp; Denisenko, Andrej; Paschos, Odysseas; Schneider, Oliver; Stimming, Ulrich

2011-12-06

Gold nanoparticles were prepared by electrochemical deposition on highly oriented pyrolytic graphite (HOPG) and boron-doped, epitaxial 100-oriented diamond layers. Using a potentiostatic double pulse technique, the average particle size was varied in the range from 5 nm to 30 nm in the case of HOPG as a support and between < 1 nm and 15 nm on diamond surfaces, while keeping the particle density constant. The distribution of particle sizes was very narrow, with standard deviations of around 20% on HOPG and around 30% on diamond. The electrocatalytic activity towards hydrogen evolution and oxygen reduction of these carbon supported gold nanoparticles in dependence of the particle sizes was investigated using cyclic voltammetry. For oxygen reduction the current density normalized to the gold surface (specific current density) increased for decreasing particle size. In contrast, the specific current density of hydrogen evolution showed no dependence on particle size. For both reactions, no effect of the different carbon supports on electrocatalytic activity was observed.

Minimum-sized ideal reactor for continuous alcohol fermentation using immobilized microorganism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamane, T.; Shimizu, S.

Recently, alcohol fermentation has gained considerable attention with the aim of lowering its production cost in the production processes of both fuel ethanol and alcoholic beverages. The over-all cost is a summation of costs of various subsystems such as raw material (sugar, starch, and cellulosic substances) treatment, fermentation process, and alcohol separation from water solutions; lowering the cost of the fermentation processes is very important in lowering the total cost. Several new techniques have been developed for economic continuous ethanol production, use of a continuous wine fermentor with no mechanical stirring, cell recycle combined with continuous removal of ethanol undermore » vaccum, a technique involving a bed of yeast admixed with an inert carrier, and use of immobilized yeast reactors in packed-bed column and in a three-stage double conical fluidized-bed bioreactor. All these techniques lead to increases more or less, in reactor productivity, which in turn result in the reduction of the reactor size for a given production rate and a particular conversion. Since an improvement in the fermentation process often leads to a reduction of fermentor size and hence, a lowering of the initial construction cost, it is important to theoretically arrive at a solution to what is the minimum-size setup of ideal reactors from the viewpoint of liquid backmixing. In this short communication, the minimum-sized ideal reactor for continuous alcohol fermentation using immobilized cells will be specifically discussed on the basis of a mathematical model. The solution will serve for designing an optimal bioreactor. (Refs. 26).« less

Modulation and synchronization technique for MF-TDMA system

NASA Technical Reports Server (NTRS)

Faris, Faris; Inukai, Thomas; Sayegh, Soheil

1994-01-01

This report addresses modulation and synchronization techniques for a multi-frequency time division multiple access (MF-TDMA) system with onboard baseband processing. The types of synchronization techniques analyzed are asynchronous (conventional) TDMA, preambleless asynchronous TDMA, bit synchronous timing with a preamble, and preambleless bit synchronous timing. Among these alternatives, preambleless bit synchronous timing simplifies onboard multicarrier demultiplexer/demodulator designs (about 2:1 reduction in mass and power), requires smaller onboard buffers (10:1 to approximately 3:1 reduction in size), and provides better frame efficiency as well as lower onboard processing delay. Analysis and computer simulation illustrate that this technique can support a bit rate of up to 10 Mbit/s (or higher) with proper selection of design parameters. High bit rate transmission may require Doppler compensation and multiple phase error measurements. The recommended modulation technique for bit synchronous timing is coherent QPSK with differential encoding for the uplink and coherent QPSK for the downlink.

Particle-size reduction of Si3N4 powder with Si3N4 milling hardware

NASA Technical Reports Server (NTRS)

Herbell, T. P.; Freedman, M. R.; Kiser, J. D.

1986-01-01

The grinding of Si3N4 powder using reaction bonded Si3N4 attrition, vibratory, and ball mills with Si3N4 media was examined. The rate of particle size reduction and the change in the chemical composition of the powder were determined in order to compare the grinding efficiency and the increase in impurity content resulting from mill and media wear for each technique. Attrition and vibratory milling exhibited rates of specific surface area increase that were approximately eight times that observed in ball milling. Vibratory milling introduced the greatest impurity pickup.

DEMONSTRATION BULLETIN: SOIL/SEDIMENT WASHING SYSTEM BERGMANN USA

EPA Science Inventory

The Bergmann USA Soil/Sediment Washing System is a waste minimization technique designed to separate or "partition" soils and sediments by grain size and density. In this water-based volume reduction process, hazardous contaminants are concentrated into a small residual portion...

Three Averaging Techniques for Reduction of Antenna Temperature Variance Measured by a Dicke Mode, C-Band Radiometer

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.; Lawrence, Roland W.

2000-01-01

As new radiometer technologies provide the possibility of greatly improved spatial resolution, their performance must also be evaluated in terms of expected sensitivity and absolute accuracy. As aperture size increases, the sensitivity of a Dicke mode radiometer can be maintained or improved by application of any or all of three digital averaging techniques: antenna data averaging with a greater than 50% antenna duty cycle, reference data averaging, and gain averaging. An experimental, noise-injection, benchtop radiometer at C-band showed a 68.5% reduction in Delta-T after all three averaging methods had been applied simultaneously. For any one antenna integration time, the optimum 34.8% reduction in Delta-T was realized by using an 83.3% antenna/reference duty cycle.

Techniques of laparoscopic cholecystectomy: Nomenclature and selection.

PubMed

Haribhakti, Sanjiv P; Mistry, Jitendra H

2015-01-01

There are more than 50 different techniques of laparoscopic cholecystectomy (LC) available in literature mainly due to modifications by surgeons in aim to improve postoperative outcome and cosmesis. These modifications include reduction in port size and/or number than what is used in standard LC. There is no uniform nomenclature to describe these different techniques so that it is not possible to compare the outcomes of different techniques. We brief the advantages and disadvantages of each of these techniques and suggest the situation where particular technique would be useful. We also propose a nomenclature which is easy to remember and apply, so that any future comparison will be possible between the techniques.

Structural mode significance using INCA. [Interactive Controls Analysis computer program

NASA Technical Reports Server (NTRS)

Bauer, Frank H.; Downing, John P.; Thorpe, Christopher J.

1990-01-01

Structural finite element models are often too large to be used in the design and analysis of control systems. Model reduction techniques must be applied to reduce the structural model to manageable size. In the past, engineers either performed the model order reduction by hand or used distinct computer programs to retrieve the data, to perform the significance analysis and to reduce the order of the model. To expedite this process, the latest version of INCA has been expanded to include an interactive graphical structural mode significance and model order reduction capability.

A Facile pH Controlled Citrate-Based Reduction Method for Gold Nanoparticle Synthesis at Room Temperature.

PubMed

Tyagi, Himanshu; Kushwaha, Ajay; Kumar, Anshuman; Aslam, Mohammed

2016-12-01

The synthesis of gold nanoparticles using citrate reduction process has been revisited. A simplified room temperature approach to standard Turkevich synthesis is employed to obtain fairly monodisperse gold nanoparticles. The role of initial pH alongside the concentration ratio of reactants is explored for the size control of Au nanoparticles. The particle size distribution has been investigated using UV-vis spectroscopy and transmission electron microscope (TEM). At optimal pH of 5, gold nanoparticles obtained are highly monodisperse and spherical in shape and have narrower size distribution (sharp surface plasmon at 520 nm). For other pH conditions, particles are non-uniform and polydisperse, showing a red-shift in plasmon peak due to aggregation and large particle size distribution. The room temperature approach results in highly stable "colloidal" suspension of gold nanoparticles. The stability test through absorption spectroscopy indicates no sign of aggregation for a month. The rate of reduction of auric ionic species by citrate ions is determined via UV absorbance studies. The size of nanoparticles under various conditions is thus predicted using a theoretical model that incorporates nucleation, growth, and aggregation processes. The faster rate of reduction yields better size distribution for optimized pH and reactant concentrations. The model involves solving population balance equation for continuously evolving particle size distribution by discretization techniques. The particle sizes estimated from the simulations (13 to 25 nm) are close to the experimental ones (10 to 32 nm) and corroborate the similarity of reaction processes at 300 and 373 K (classical Turkevich reaction). Thus, substitution of experimentally measured rate of disappearance of auric ionic species into theoretical model enables us to capture the unusual experimental observations.

Background field removal technique using regularization enabled sophisticated harmonic artifact reduction for phase data with varying kernel sizes.

PubMed

Kan, Hirohito; Kasai, Harumasa; Arai, Nobuyuki; Kunitomo, Hiroshi; Hirose, Yasujiro; Shibamoto, Yuta

2016-09-01

An effective background field removal technique is desired for more accurate quantitative susceptibility mapping (QSM) prior to dipole inversion. The aim of this study was to evaluate the accuracy of regularization enabled sophisticated harmonic artifact reduction for phase data with varying spherical kernel sizes (REV-SHARP) method using a three-dimensional head phantom and human brain data. The proposed REV-SHARP method used the spherical mean value operation and Tikhonov regularization in the deconvolution process, with varying 2-14mm kernel sizes. The kernel sizes were gradually reduced, similar to the SHARP with varying spherical kernel (VSHARP) method. We determined the relative errors and relationships between the true local field and estimated local field in REV-SHARP, VSHARP, projection onto dipole fields (PDF), and regularization enabled SHARP (RESHARP). Human experiment was also conducted using REV-SHARP, VSHARP, PDF, and RESHARP. The relative errors in the numerical phantom study were 0.386, 0.448, 0.838, and 0.452 for REV-SHARP, VSHARP, PDF, and RESHARP. REV-SHARP result exhibited the highest correlation between the true local field and estimated local field. The linear regression slopes were 1.005, 1.124, 0.988, and 0.536 for REV-SHARP, VSHARP, PDF, and RESHARP in regions of interest on the three-dimensional head phantom. In human experiments, no obvious errors due to artifacts were present in REV-SHARP. The proposed REV-SHARP is a new method combined with variable spherical kernel size and Tikhonov regularization. This technique might make it possible to be more accurate backgroud field removal and help to achive better accuracy of QSM. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of laser-assisted lipolysis on nipple-areola complex.

PubMed

Sönmez Ergün, Selma; Kayan, Reşit Burak; Güleş, Mustafa Ekrem; Kuzu, İsmail Melih

2017-08-01

Gynecomastia, as a most common benign condition, represents itself as the enlargement of the male breast and also nipple-areola complex as the severity of the condition increases. With this study, we aimed to clarify the effects of 980-nm diode laser on nipple-areola complex (NAC). Although numerous open techniques have been described to correct gynecomastia, nowadays trends have shifted to minimally invasive techniques such as laser-assisted lipolysis (LAL). A total of 25 patients with bilateral gynecomastia treated with LAL by using a 980-nm diode laser. The resultant contour and reduced size of the complex were satisfactory. LAL leads to significant reduction of the size of NAC.

Model reduction by trimming for a class of semi-Markov reliability models and the corresponding error bound

NASA Technical Reports Server (NTRS)

White, Allan L.; Palumbo, Daniel L.

1991-01-01

Semi-Markov processes have proved to be an effective and convenient tool to construct models of systems that achieve reliability by redundancy and reconfiguration. These models are able to depict complex system architectures and to capture the dynamics of fault arrival and system recovery. A disadvantage of this approach is that the models can be extremely large, which poses both a model and a computational problem. Techniques are needed to reduce the model size. Because these systems are used in critical applications where failure can be expensive, there must be an analytically derived bound for the error produced by the model reduction technique. A model reduction technique called trimming is presented that can be applied to a popular class of systems. Automatic model generation programs were written to help the reliability analyst produce models of complex systems. This method, trimming, is easy to implement and the error bound easy to compute. Hence, the method lends itself to inclusion in an automatic model generator.

Lumped element filters for electronic warfare systems

NASA Astrophysics Data System (ADS)

Morgan, D.; Ragland, R.

1986-02-01

Increasing demands which future generations of electronic warfare (EW) systems are to satisfy include a reduction in the size of the equipment. The present paper is concerned with lumped element filters which can make a significant contribution to the downsizing of advanced EW systems. Lumped element filter design makes it possible to obtain very small package sizes by utilizing classical low frequency inductive and capacitive components which are small compared to the size of a wavelength. Cost-effective, temperature-stable devices can be obtained on the basis of new design techniques. Attention is given to aspects of design flexibility, an interdigital filter equivalent circuit diagram, conditions for which the use of lumped element filters can be recommended, construction techniques, a design example, and questions regarding the application of lumped element filters to EW processing systems.

A Meta-Analytic Review of Stand-Alone Interventions to Improve Body Image

PubMed Central

Alleva, Jessica M.; Sheeran, Paschal; Webb, Thomas L.; Martijn, Carolien; Miles, Eleanor

2015-01-01

Objective Numerous stand-alone interventions to improve body image have been developed. The present review used meta-analysis to estimate the effectiveness of such interventions, and to identify the specific change techniques that lead to improvement in body image. Methods The inclusion criteria were that (a) the intervention was stand-alone (i.e., solely focused on improving body image), (b) a control group was used, (c) participants were randomly assigned to conditions, and (d) at least one pretest and one posttest measure of body image was taken. Effect sizes were meta-analysed and moderator analyses were conducted. A taxonomy of 48 change techniques used in interventions targeted at body image was developed; all interventions were coded using this taxonomy. Results The literature search identified 62 tests of interventions (N = 3,846). Interventions produced a small-to-medium improvement in body image (d + = 0.38), a small-to-medium reduction in beauty ideal internalisation (d + = -0.37), and a large reduction in social comparison tendencies (d + = -0.72). However, the effect size for body image was inflated by bias both within and across studies, and was reliable but of small magnitude once corrections for bias were applied. Effect sizes for the other outcomes were no longer reliable once corrections for bias were applied. Several features of the sample, intervention, and methodology moderated intervention effects. Twelve change techniques were associated with improvements in body image, and three techniques were contra-indicated. Conclusions The findings show that interventions engender only small improvements in body image, and underline the need for large-scale, high-quality trials in this area. The review identifies effective techniques that could be deployed in future interventions. PMID:26418470

Techniques of laparoscopic cholecystectomy: Nomenclature and selection

PubMed Central

Haribhakti, Sanjiv P.; Mistry, Jitendra H.

2015-01-01

There are more than 50 different techniques of laparoscopic cholecystectomy (LC) available in literature mainly due to modifications by surgeons in aim to improve postoperative outcome and cosmesis. These modifications include reduction in port size and/or number than what is used in standard LC. There is no uniform nomenclature to describe these different techniques so that it is not possible to compare the outcomes of different techniques. We brief the advantages and disadvantages of each of these techniques and suggest the situation where particular technique would be useful. We also propose a nomenclature which is easy to remember and apply, so that any future comparison will be possible between the techniques. PMID:25883450

Application of the combinative particle size reduction technology H 42 to produce fast dissolving glibenclamide tablets.

PubMed

Salazar, Jaime; Müller, Rainer H; Möschwitzer, Jan P

2013-07-16

Standard particle size reduction techniques such as high pressure homogenization or wet bead milling are frequently used in the production of nanosuspensions. The need for micronized starting material and long process times are their evident disadvantages. Combinative particle size reduction technologies have been developed to overcome the drawbacks of the standard techniques. The H 42 combinative technology consists of a drug pre-treatment by means of spray-drying followed by standard high pressure homogenization. In the present paper, spray-drying process parameters influencing the diminution effectiveness, such as drug and surfactant concentration, were systematically analyzed. Subsequently, the untreated and pre-treated drug powders were homogenized for 20 cycles at 1500 bar. For untreated, micronized glibenclamide, the particle size analysis revealed a mean particle size of 772 nm and volume-based size distribution values of 2.686 μm (d50%) and 14.423 μm (d90%). The use of pre-treated material (10:1 glibenclamide/docusate sodium salt ratio spray-dried as ethanolic solution) resulted in a mean particle size of 236 nm and volume-based size distribution values of 0.131 μm (d50%) and 0.285 μm (d90%). These results were markedly improved compared to the standard process. The nanosuspensions were further transferred into tablet formulations. Wet granulation, freeze-drying and spray-drying were investigated as downstream methods to produce dry intermediates. Regarding the dissolution rate, the rank order of the downstream processes was as follows: Spray-drying>freeze-drying>wet granulation. The best drug release (90% within 10 min) was obtained for tablets produced with spray-dried nanosuspension containing 2% mannitol as matrix former. In comparison, the tablets processed with micronized glibenclamide showed a drug release of only 26% after 10 min. The H 42 combinative technology could be successfully applied in the production of small drug nanocrystals. A nanosuspension transfer to tablets that maintained the fast dissolution properties of the drug nanocrystals was successfully achieved. Copyright © 2013 Elsevier B.V. All rights reserved.

A versatile breast reduction technique: Conical plicated central U shaped (COPCUs) mammaplasty

PubMed Central

Copcu, Eray

2009-01-01

Background There have been numerous studies on reduction mammaplasty and its modifications in the literature. The multitude of modifications of reduction mammaplasty indicates that the ideal technique has yet to be found. There are four reasons for seeking the ideal technique. One reason is to preserve functional features of the breast: breastfeeding and arousal. Other reasons are to achieve the real geometric and aesthetic shape of the breast with the least scar and are to minimize complications of prior surgical techniques without causing an additional complication. Last reason is the limitation of the techniques described before. To these aims, we developed a new versatile reduction mammaplasty technique, which we called conical plicated central U shaped (COPCUs) mammaplasty. Methods We performed central plication to achieve a juvenile look in the superior pole of the breast and to prevent postoperative pseudoptosis and used central U shaped flap to achieve maximum NAC safety and to preserve lactation and nipple sensation. The central U flap was 6 cm in width and the superior conical plication was performed with 2/0 PDS. Preoperative and postoperative standard measures of the breast including the superior pole fullness were compared. Results Forty six patients were operated with the above mentioned technique. All of the patients were satisfied with functional and aesthetic results and none of them had major complications. There were no changes in the nipple innervation. Six patients becoming pregnant after surgery did not experience any problems with lactation. None of the patients required scar revision. Conclusion Our technique is a versatile, safe, reliable technique which creates the least scar, avoids previously described disadvantages, provides maximum preservation of functions, can be employed in all breasts regardless of their sizes. PMID:19575809

Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support

NASA Technical Reports Server (NTRS)

Klettlinger, Jennifer Lindsey Suder

2012-01-01

The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the active site density; on the other hand, by increasing the size of the cobalt clusters, there is less likelihood of forming oxidized cobalt complexes (cobalt aluminate) during Fischer-Tropsch synthesis. Thus, from the standpoint of stability, improving the extent of reduction while increasing the particle size slightly may be beneficial for maintaining the sites, even if there is a slight decrease in overall initial active site density.

Kinetics of the reduction of bushveld complex chromite ore at 1416 °C

NASA Astrophysics Data System (ADS)

Soykan, O.; Eric, R. H.; King, R. P.

1991-12-01

The kinetics of the reduction of chromite ore from the LG-6 layer of the Bushveld Complex of the Transvaal in South Africa were studied at 1416 °C by the thermogravimetric analysis (TGA) technique. Spectroscopic graphite powder was employed as the reductant. The aim of this article is to present a kinetic model that satisfactorily describes the solid-state carbothermic reduction of chromite. A generalized rate model based on an ionic diffusion mechanism was developed. The model included the contribution of the interfacial area between partially reduced and unreduced zones in chromite particles and diffusion. The kinetic model described the process for degrees of reduction from 10 to 75 pet satisfactorily. It was observed that at a given particle size, the rate of reduction was controlled mainly by interfacial area up to about 40 pet reduction, after which the rate was dominated by diffusion. On the other hand, for a given degree of reduction, the contribution of the interfacial area to the rate increased, while that of diffusion decreased, with a decrease in the particle size. The value of the diffusion coefficient for the Fe2+ species at 1416 °C was calculated to be 2.63 x 10-2 cm2/s.

Effect of combination ultrasonic and ball milling techniques of commercial fillers dispersion on mechanical properties of natural rubber (NR) latex films

NASA Astrophysics Data System (ADS)

Hamran, Noramirah; Rashid, Azura A.

2017-07-01

Commercial fillers such as silica and carbon black generally impart the reinforcing effects in dry rubber compound, but have an adverse effect on Natural rubber (NR) latex compounds. The addition of commercial fillers in NR latex has reduced the mechanical properties of NR latex films due to the destabilization effect in the NR latex compounds which govern by the dispersion quality, particle size and also the pH of the dispersion itself. The ball milling process is the conventional meth od of preparation of dispersions and ultrasonic has successfully used in preparation of nano fillers such as carbon nanotube (CNT). In this study the combination between the conventional methods; ball milling together the ultrasonic method were used to prepare the silica and carbon black dispersions. The different duration of ball milling (24, 48 and 72 hours) was compared with the ultrasonic method (30, 60, 90 and 120 minutes). The combination of ball milling and ultrasonic from the optimum individual technique was used to investigate the reduction of particle size of the fillers. The particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test were carried out to investigate the obtained particle size and the tensile and tear test were carried out to investigate the mechanical properties of the NR latex films. The reduction of filler particle size is expected to impart the properties of NR latex films.

Renal cell carcinoma: the influence of new diagnostic imaging techniques on the size and stage of tumors diagnosed over the past 26 years.

PubMed

Touloupidis, Stavros; Papathanasiou, Athanasios; Kalaitzis, Christos; Fatles, Georgios; Manavis, Ioannis; Rombis, Vassilios

2006-01-01

We have analyzed data collected over a 26-year period for influences of new diagnostic imaging techniques (ultrasound, computed tomography, and magnetic resonance imaging) on the size, stage, and other parameters of renal cell carcinomas at the time of first diagnosis. We reviewed retrospectively the records of 203 patients who underwent operations at our institutions from 1973 to 1999. All the patients suffered from renal cell carcinoma. With this study we attempted to answer four questions regarding changes over this time span: (1) have new imaging techniques lead to a reduction in the median diameter of the tumor upon first diagnosis, (2) has the tumor stage decreased due to earlier diagnosis, (3) is there any correlation between tumor size and tumor stage, and (4) are the patient's early diagnoses at a younger age? Other parameters such as infiltration of the renal pelvis and the cell type were also examined. The tumor size and stage at the time of diagnosis and treatment are positively correlated, and both decrease significantly over the time span examined. There is also a strong association between tumor size and infiltration of the renal pelvis. The median age of the patients did not significantly change over time. The wider use of improved imaging techniques has significantly changed the clinical appearance of the renal cell carcinoma. The question is whether these techniques have also affected the prognosis of the disease.

Cannon shredding of municipal solid waste for the preparation of biological feedstock

NASA Astrophysics Data System (ADS)

Burke, J.

1981-04-01

Explosive decompression as a method of size reduction of materials found in municipal solid waste (MSW) was studied and preliminary data related to the handling and wet separation of exploded material was gathered. Steam was emphasized as the source of pressure. Municipal refuse was placed in an 8-ft long, 10.75-in. ID steel cannon which was sealed and pressurized. After an appropriate time, the cannon muzzle closure was opened and the test material expelled from the cannon through a constrictive orifice, resulting in explosive decompression. Flash evaporation of pressurized saturated water, expansion of steam, and the strong turbulence at the cannon muzzle accomplished size reduction. Hydraulic processing is shown to be an effective technique for separating heavy and light fractions.

Data on Support Vector Machines (SVM) model to forecast photovoltaic power.

PubMed

Malvoni, M; De Giorgi, M G; Congedo, P M

2016-12-01

The data concern the photovoltaic (PV) power, forecasted by a hybrid model that considers weather variations and applies a technique to reduce the input data size, as presented in the paper entitled "Photovoltaic forecast based on hybrid pca-lssvm using dimensionality reducted data" (M. Malvoni, M.G. De Giorgi, P.M. Congedo, 2015) [1]. The quadratic Renyi entropy criteria together with the principal component analysis (PCA) are applied to the Least Squares Support Vector Machines (LS-SVM) to predict the PV power in the day-ahead time frame. The data here shared represent the proposed approach results. Hourly PV power predictions for 1,3,6,12, 24 ahead hours and for different data reduction sizes are provided in Supplementary material.

A Compton scattering technique to determine wood density and locating defects in it

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tondon, Akash, E-mail: akashtondonnsl@gmail.com; Sandhu, B. S.; Singh, Bhajan

A Compton scattering technique is presented to determine density and void location in the given wooden samples. The technique uses a well collimated gamma ray beam from {sup 137}Cs along with the NaI(Tl) scintillation detector. First, a linear relationship is established between Compton scattered intensity and known density of chemical compounds, and then density of the wood is determined from this linear relation. In another experiment, the ability of penetration of gamma rays is explored to detect voids in wooden (low Z) sample. The sudden reduction in the Compton scattered intensities agrees well with the position and size of voidsmore » in the wooden sample. It is concluded that wood density and the voids of size ∼ 4 mm and more can be detected easily by this method.« less

Enhanced algorithms for stochastic programming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna, Alamuru S.

1993-09-01

In this dissertation, we present some of the recent advances made in solving two-stage stochastic linear programming problems of large size and complexity. Decomposition and sampling are two fundamental components of techniques to solve stochastic optimization problems. We describe improvements to the current techniques in both these areas. We studied different ways of using importance sampling techniques in the context of Stochastic programming, by varying the choice of approximation functions used in this method. We have concluded that approximating the recourse function by a computationally inexpensive piecewise-linear function is highly efficient. This reduced the problem from finding the mean ofmore » a computationally expensive functions to finding that of a computationally inexpensive function. Then we implemented various variance reduction techniques to estimate the mean of a piecewise-linear function. This method achieved similar variance reductions in orders of magnitude less time than, when we directly applied variance-reduction techniques directly on the given problem. In solving a stochastic linear program, the expected value problem is usually solved before a stochastic solution and also to speed-up the algorithm by making use of the information obtained from the solution of the expected value problem. We have devised a new decomposition scheme to improve the convergence of this algorithm.« less

Effect of Platelet-rich Fibrin on Healing of Apicomarginal Defects: A Randomized Controlled Trial.

PubMed

Dhiman, Meenu; Kumar, Suresh; Duhan, Jigyasa; Sangwan, Pankaj; Tewari, Sanjay

2015-07-01

The purpose of this prospective, randomized controlled trial was to evaluate the healing outcomes of platelet-rich fibrin (PRF) in periapical surgeries involving apicomarginal defects and to compare these results with surgeries not using any guided tissue regeneration techniques. Thirty patients with suppurative chronic apical periodontitis and apicomarginal communication were randomly assigned to either the PRF or the control group. Clinical and radiographic parameters including pocket depth (PD), clinical attachment level, gingival marginal position, size of periapical lesion, and percentage reduction of the periapical radiolucency were recorded at baseline and at an interval of 3 months for a period of 12 months. The overall success rate was 83.33%, with a success rate of 86.66% (13 of 15 teeth) for PRF group and 80% (12 of 15 teeth) for control group. Both the groups exhibited a significant reduction in PD, clinical attachment level, gingival marginal position, and size of periapical lesion at 12-month period. No significant differences were observed between the 2 groups for these parameters except PD, which showed a statistically significant reduction in the PRF group (P < .05). The adjunctive use of regenerative techniques may not promote healing of apicomarginal defects of endodontic origin. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Computerized mass detection in whole breast ultrasound images: reduction of false positives using bilateral subtraction technique

NASA Astrophysics Data System (ADS)

Ikedo, Yuji; Fukuoka, Daisuke; Hara, Takeshi; Fujita, Hiroshi; Takada, Etsuo; Endo, Tokiko; Morita, Takako

2007-03-01

The comparison of left and right mammograms is a common technique used by radiologists for the detection and diagnosis of masses. In mammography, computer-aided detection (CAD) schemes using bilateral subtraction technique have been reported. However, in breast ultrasonography, there are no reports on CAD schemes using comparison of left and right breasts. In this study, we propose a scheme of false positive reduction based on bilateral subtraction technique in whole breast ultrasound images. Mass candidate regions are detected by using the information of edge directions. Bilateral breast images are registered with reference to the nipple positions and skin lines. A false positive region is detected based on a comparison of the average gray values of a mass candidate region and a region with the same position and same size as the candidate region in the contralateral breast. In evaluating the effectiveness of the false positive reduction method, three normal and three abnormal bilateral pairs of whole breast images were employed. These abnormal breasts included six masses larger than 5 mm in diameter. The sensitivity was 83% (5/6) with 13.8 (165/12) false positives per breast before applying the proposed reduction method. By applying the method, false positives were reduced to 4.5 (54/12) per breast without removing a true positive region. This preliminary study indicates that the bilateral subtraction technique is effective for improving the performance of a CAD scheme in whole breast ultrasound images.

Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

PubMed

Ardley, Nicholas D; Lau, Ken K; Buchan, Kevin

2013-12-01

Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

A novel reduction approach to fabricate quantum-sized SnO₂-conjugated reduced graphene oxide nanocomposites as non-enzymatic glucose sensors.

PubMed

Ye, Yixing; Wang, Panpan; Dai, Enmei; Liu, Jun; Tian, Zhenfei; Liang, Changhao; Shao, Guosheng

2014-05-21

Quantum-sized SnO2 nanocrystals can be well dispersed on reduced graphene oxide (rGO) nanosheets through a convenient one-pot in situ reduction route without using any other chemical reagent or source. Highly reactive metastable tin oxide (SnO(x)) nanoparticles (NPs) were used as reducing agents and composite precursors derived by the laser ablation in liquid (LAL) technique. Moreover, the growth and phase transition of LAL-induced SnO(x) NPs and graphene oxide (GO) were examined by optical absorption, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and high-resolution transmission electron microscopy. Highly dispersed SnO(x) NPs can also prevent rGO from being restacked into a multilayer structure during GO reduction. Given the good electron transfer ability and unsaturated dangling bonds of rGO, as well as the ample electrocatalytic active sites of quantum-sized SnO2 NPs on unfolded rGO sheets, the fabricated SnO2-rGO nanocomposite exhibited excellent performance in the non-enzymatic electrochemical detection of glucose molecules. The use of LAL-induced reactive NPs for in situ GO reduction is also expected to be a universal and environmentally friendly approach for the formation of various rGO-based nanocomposites.

Parallel State Space Construction for a Model Checking Based on Maximality Semantics

NASA Astrophysics Data System (ADS)

El Abidine Bouneb, Zine; Saīdouni, Djamel Eddine

2009-03-01

The main limiting factor of the model checker integrated in the concurrency verification environment FOCOVE [1, 2], which use the maximality based labeled transition system (noted MLTS) as a true concurrency model[3, 4], is currently the amount of available physical memory. Many techniques have been developed to reduce the size of a state space. An interesting technique among them is the alpha equivalence reduction. Distributed memory execution environment offers yet another choice. The main contribution of the paper is to show that the parallel state space construction algorithm proposed in [5], which is based on interleaving semantics using LTS as semantic model, may be adapted easily to the distributed implementation of the alpha equivalence reduction for the maximality based labeled transition systems.

Zone plate method for electronic holographic display using resolution redistribution technique.

PubMed

Takaki, Yasuhiro; Nakamura, Junya

2011-07-18

The resolution redistribution (RR) technique can increase the horizontal viewing-zone angle and screen size of electronic holographic display. The present study developed a zone plate method that would reduce hologram calculation time for the RR technique. This method enables calculation of an image displayed on a spatial light modulator by performing additions of the zone plates, while the previous calculation method required performing the Fourier transform twice. The derivation and modeling of the zone plate are shown. In addition, the look-up table approach was introduced for further reduction in computation time. Experimental verification using a holographic display module based on the RR technique is presented.

Determination of calibration parameters of a VRX CT system using an “Amoeba” algorithm

PubMed Central

Jordan, Lawrence M.; DiBianca, Frank A.; Melnyk, Roman; Choudhary, Apoorva; Shukla, Hemant; Laughter, Joseph; Gaber, M. Waleed

2008-01-01

Efforts to improve the spatial resolution of CT scanners have focused mainly on reducing the source and detector element sizes, ignoring losses from the size of the secondary-ionization charge “clouds” created by the detected x-ray photons, i.e., the “physics limit.” This paper focuses on implementing a technique called “projective compression.” which allows further reduction in effective cell size while overcoming the physics limit as well. Projective compression signifies detector geometries in which the apparent cell size is smaller than the physical cell size, allowing large resolution boosts. A realization of this technique has been developed with a dual-arm “variable-resolution x-ray” (VRX) detector. Accurate values of the geometrical parameters are needed to convert VRX outputs to formats ready for optimal image reconstruction by standard CT techniques. The required calibrating data are obtained by scanning a rotating pin and fitting a theoretical parametric curve (using a multi-parameter minimization algorithm) to the resulting pin sinogram. Excellent fits are obtained for both detector-arm sections with an average (maximum) fit deviation of ~0.05 (0.1) detector cell width. Fit convergence and sensitivity to starting conditions are considered. Pre- and post-optimization reconstructions of the alignment pin and a biological subject reconstruction after calibration are shown. PMID:19430581

Determination of calibration parameters of a VRX CT system using an "Amoeba" algorithm.

PubMed

Jordan, Lawrence M; Dibianca, Frank A; Melnyk, Roman; Choudhary, Apoorva; Shukla, Hemant; Laughter, Joseph; Gaber, M Waleed

2004-01-01

Efforts to improve the spatial resolution of CT scanners have focused mainly on reducing the source and detector element sizes, ignoring losses from the size of the secondary-ionization charge "clouds" created by the detected x-ray photons, i.e., the "physics limit." This paper focuses on implementing a technique called "projective compression." which allows further reduction in effective cell size while overcoming the physics limit as well. Projective compression signifies detector geometries in which the apparent cell size is smaller than the physical cell size, allowing large resolution boosts. A realization of this technique has been developed with a dual-arm "variable-resolution x-ray" (VRX) detector. Accurate values of the geometrical parameters are needed to convert VRX outputs to formats ready for optimal image reconstruction by standard CT techniques. The required calibrating data are obtained by scanning a rotating pin and fitting a theoretical parametric curve (using a multi-parameter minimization algorithm) to the resulting pin sinogram. Excellent fits are obtained for both detector-arm sections with an average (maximum) fit deviation of ~0.05 (0.1) detector cell width. Fit convergence and sensitivity to starting conditions are considered. Pre- and post-optimization reconstructions of the alignment pin and a biological subject reconstruction after calibration are shown.

Graft downsizing during ex vivo lung perfusion: case report and technical notes.

PubMed

Nosotti, M; Rosso, L; Mendogni, P; Tosi, D; Palleschi, A; Righi, I; Froio, S; Valenza, F; Santambrogio, L

2014-09-01

Among patients with respiratory insufficiency awaiting lung transplantation, small adult patients have a lower opportunity of receiving size-matched pulmonary grafts, because of the shortage of donors, particularly those of small size. Reducing the size of an oversized graft is one of the methods to increase the donor pool; similarly, ex vivo lung perfusion is an emerging technique aimed toward the same purpose. We describe how we combined the 2 techniques (lobar transplantation plus contralateral nonanatomic graft reduction during ex vivo lung perfusion) to overcome graft shortage in a clinical case. For the 1st time, this case report demonstrates that surgical manipulation during ex vivo lung perfusion does not affect the functional improvement in a lung previously judged to be not suitable for transplantation. The 6-month follow-up results are similar to those of standard bilateral lung transplantation. Copyright © 2014 Elsevier Inc. All rights reserved.

Mixed sediment beach processes: Kachemak Bay, Alaska

USGS Publications Warehouse

Ruggiero, P.; Adams, P.N.; Warrick, J.A.

2007-01-01

Mixed sediment beaches are morphologically distinct from and more complex than either sand or gravel only beaches. Three digital imaging techniques are employed to quantify surficial grain size and bedload sediment transport rates along the mixed sediment beaches of Kachemak Bay, Alaska. Applying digital imaging procedures originally developed for quickly and efficiently quantifying grain sizes of sand to coarse sediment classes gives promising results. Hundreds of grain size estimates lead to a quantitative characterization of the region's sediment at a significant reduction in cost and time as compared to traditional techniques. Both the sand and coarse fractions on this megatidal beach mobilize into self-organized bedforms that migrate alongshore with a seasonally reflecting the temporal pattern of the alongshore component of wave power. In contrast, the gravel bedforms also migrate in the cross-shore without significant seasonally suggesting that swash asymmetry is sufficient to mobilize the gravel even during low energy summer conditions. ?? 2007 ASCE.

An adaptive incremental approach to constructing ensemble classifiers: application in an information-theoretic computer-aided decision system for detection of masses in mammograms.

PubMed

Mazurowski, Maciej A; Zurada, Jacek M; Tourassi, Georgia D

2009-07-01

Ensemble classifiers have been shown efficient in multiple applications. In this article, the authors explore the effectiveness of ensemble classifiers in a case-based computer-aided diagnosis system for detection of masses in mammograms. They evaluate two general ways of constructing subclassifiers by resampling of the available development dataset: Random division and random selection. Furthermore, they discuss the problem of selecting the ensemble size and propose two adaptive incremental techniques that automatically select the size for the problem at hand. All the techniques are evaluated with respect to a previously proposed information-theoretic CAD system (IT-CAD). The experimental results show that the examined ensemble techniques provide a statistically significant improvement (AUC = 0.905 +/- 0.024) in performance as compared to the original IT-CAD system (AUC = 0.865 +/- 0.029). Some of the techniques allow for a notable reduction in the total number of examples stored in the case base (to 1.3% of the original size), which, in turn, results in lower storage requirements and a shorter response time of the system. Among the methods examined in this article, the two proposed adaptive techniques are by far the most effective for this purpose. Furthermore, the authors provide some discussion and guidance for choosing the ensemble parameters.

Biatrial reduction plasty with reef imbricate technique as an adjunct to maze procedure for permanent atrial fibrillation associated with giant left atria.

PubMed

Wang, William; Guo, L Ray; Martland, Anne Marie; Feng, Xiao-Dong; Ma, Jie; Feng, Xi Qing

2010-04-01

Success of the modified maze procedure after valvular operation with giant atria and permanent atrial fibrillation (AF) remains suboptimal. We report an aggressive approach for these patients utilizing biatrial reduction plasty with a reef imbricate suture technique concomitantly with valvular and maze procedure for AF. From January 1999 to December 2006, 122 consecutive Chinese patients with permanent AF and biatrial enlargement who required mitral valve+/-tricuspid valve (TV) surgery underwent aggressive left atrial reduction combined with radiofrequency bipolar full maze procedure. Left atrial dimensions were measured by TTE or TEE. There were 71 women (58.1%) and 51 men (41.9%) and their mean age was 45+/-9.5 years. Mean duration of AF was 48.4+/-21.4 months. All patients underwent left atrial reduction plasty with reef imbricate suture technique and full maze procedure. Their preoperative left atria measured 64+/-12 mm in the enlarged left atria (ELA) group and 86+/-17 mm in the giant left atria (GLA). Mitral valve replacement (MVR) combined with TV repair was performed in 102 patients (83%) while 21 patients underwent MVRs combined with aortic valve replacements (17%). Sixty-six (54%) patients required additional procedures and 61 (50%) of the patients also underwent left atrial appendage clot evacuation. Postoperative left atrial size was reduced to 49+/-8 mm (ELA) and 51+/-11 mm (GLA), respectively (P<0.05). Ninety-three of 122 (76%) patients were restored in normal sinus rhythm after one year clinical follow-up. Aggressive biatrial reduction plasty combined with full maze procedure is an effective treatment for patients with permanent AF undergoing concomitant valvular surgery. Further studies utilizing the reef imbricate suture technique for atrial reduction need to subsequently be evaluated.

Metal/Carbon Hybrid Nanostructures Produced from Plasma-Enhanced Chemical Vapor Deposition over Nafion-Supported Electrochemically Deposited Cobalt Nanoparticles

PubMed Central

Achour, Amine; Saeed, Khalid; Djouadi, Mohamed Abdou

2018-01-01

In this work, we report development of hybrid nanostructures of metal nanoparticles (NP) and carbon nanostructures with strong potential for catalysis, sensing, and energy applications. First, the etched silicon wafer substrates were passivated for subsequent electrochemical (EC) processing through grafting of nitro phenyl groups using para-nitrobenzene diazonium (PNBT). The X-ray photoelectron spectroscope (XPS) and atomic force microscope (AFM) studies confirmed presence of few layers. Cobalt-based nanoparticles were produced over dip or spin coated Nafion films under different EC reduction conditions, namely CoSO4 salt concentration (0.1 M, 1 mM), reduction time (5, 20 s), and indirect or direct EC reduction route. Extensive AFM examination revealed NP formation with different attributes (size, distribution) depending on electrochemistry conditions. While relatively large NP with >100 nm size and bimodal distribution were obtained after 20 s EC reduction in H3BO3 following Co2+ ion uptake, ultrafine NP (<10 nm) could be produced from EC reduction in CoSO4 and H3BO3 mixed solution with some tendency to form oxides. Different carbon nanostructures including few-walled or multiwalled carbon nanotubes (CNT) and carbon nanosheets were grown in a C2H2/NH3 plasma using the plasma-enhanced chemical vapor deposition technique. The devised processing routes enable size controlled synthesis of cobalt nanoparticles and metal/carbon hybrid nanostructures with unique microstructural features. PMID:29702583

The optical and structural properties of graphene nanosheets and tin oxide nanocrystals composite

NASA Astrophysics Data System (ADS)

Farheen, Parveen, Azra; Azam, Ameer

2018-05-01

A nanocomposite material consisting of metal oxide and reduced graphene oxide was prepared via simple, economic, and effective chemical reduction method. The synthesis strategy was based on the reduction of GO with Sn2+ ion that combines tin oxidation and GO reduction in one step, which provides a simple, low-cost and effective way to prepare graphene nanosheets/SnO2 nanocrystals composites because no additional chemicals were needed. SEM and TEM images shows the uniform distribution of the SnO2 nanocrystals on the Graphene nanosheets (GNs) surface and transmission electron microscope shows an average particle size of 2-4 nm. The mean crystallite size was calculated by Debye Scherrer formula and was found to be about 4.0 nm. Optical analysis was done by using UV-Visible spectroscopy technique and the band gap energy of the GNs/SnO2 nanocomposite was calculated by Tauc relation and came out to be 3.43eV.

Kinetic studies on the reduction of iron ore nuggets by devolatilization of lean-grade coal

NASA Astrophysics Data System (ADS)

Biswas, Chanchal; Gupta, Prithviraj; De, Arnab; Chaudhuri, Mahua Ghosh; Dey, Rajib

2016-12-01

An isothermal kinetic study of a novel technique for reducing agglomerated iron ore by volatiles released by pyrolysis of lean-grade non-coking coal was carried out at temperature from 1050 to 1200°C for 10-120 min. The reduced samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis. A good degree of metallization and reduction was achieved. Gas diffusion through the solid was identified as the reaction-rate-controlling resistance; however, during the initial period, particularly at lower temperatures, resistance to interfacial chemical reaction was also significant, though not dominant. The apparent rate constant was observed to increase marginally with decreasing size of the particles constituting the nuggets. The apparent activation energy of reduction was estimated to be in the range from 49.640 to 51.220 kJ/mol and was not observed to be affected by the particle size. The sulfur and carbon contents in the reduced samples were also determined.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furuta, H.; Imura, A.; Furuta, Y.

Recently, technique of Gadolinium loaded liquid scintillator (Gd-LS) for reactor neutrino oscillation experiments has attracted attention as a monitor of reactor operation and 'nuclear Gain (GA)' for IAEA safeguards. For the practical use, R and D of the 1 ton class compact detector, which is measurable above ground, is necessary. Especially, it is important to reduce much amount of fast neutron background induced by cosmic muons with data analysis for the measurement above ground. We developed a prototype of the Gd-LS detector with 200 L of the target volume, which has Pulse Shape Discrimination (PSD) ability for the fast neutronmore » reduction with data analysis. Usually, it is well known that it is difficult to keep high fast neutron reduction power of PSD with the large volume size such as the neutrino reactor monitor. We evaluated the PSD ability of our prototype with real fast neutrons induced by the muons in our laboratory above ground, and we could confirm to keep the high fast neutron reduction power with even our large detector size. (authors)« less

Improved consolidation of silicon carbide

NASA Technical Reports Server (NTRS)

Freedman, M. R.; Millard, M. L.

1986-01-01

Alpha silicon carbide powder was consolidated by both dry and wet methods. Dry pressing in a double acting steel die yielded sintered test bars with an average flexural strength of 235.6 MPa with a critical flaw size of approximately 100 micro m. An aqueous slurry pressing technique produced sintered test bars with an average flexural strength of 440.8 MPa with a critical flaw size of approximately 25 micro m. Image analysis revealed a reduction in both pore area and pore size distribution in the slurry pressed sintered test bars. The improvements in the slurry pressed material properties are discussed in terms of reduced agglomeration and improved particle packing during consolidation.

Arbitrary shape region-of-interest fluoroscopy system

NASA Astrophysics Data System (ADS)

Xu, Tong; Le, Huy; Molloi, Sabee Y.

2002-05-01

Region-of-interest (ROI) fluoroscopy has previously been investigated as a method to reduce x-ray exposure to the patient and the operator. This ROI fluoroscopy technique allows the operator to arbitrarily determine the shape, size, and location of the ROI. A device was used to generate patient specific x-ray beam filters. The device is comprised of 18 step-motors that control a 16 X 16 matrix of pistons to form the filter from a deformable attenuating material. Patient exposure reductions were measured to be 84 percent for a 65 kVp beam. Operator exposure reduction was measured to be 69 percent. Due to the reduced x-ray scatter, image contrast was improved by 23 percent inside the ROI. The reduced gray level in the periphery was corrected using an experimentally determined compensation ratio. A running average interpolation technique was used to eliminate the artifacts from the ROI edge. As expected, the final corrected images show increased noise in the periphery. However, the anatomical structures in the periphery could still be visualized. This arbitrary shaped region of interest fluoroscopic technique was shown to be effective in terms of its ability to reduce patient and operator exposure without significant reduction in image quality. The ability to define an arbitrary shaped ROI should make the technique more clinically feasible.

Specific surface to evaluate the efficiencies of milling and pretreatment of wood for enzymatic saccharification

Treesearch

Junyong Zhu; G.S. Wang; X.J. Pan; Roland Gleisner

2009-01-01

Sieving methods have been almost exclusively used for feedstock size-reduction characterization in the biomass refining literature. This study demonstrates a methodology to properly characterize specific surface of biomass substrates through two dimensional measurement of each fiber of the substrate using a wet imaging technique. The methodology provides more...

Remote ischaemic postconditioning protects the heart during acute myocardial infarction in pigs.

PubMed

Andreka, Gyorgy; Vertesaljai, Marton; Szantho, Gergely; Font, Gusztav; Piroth, Zsolt; Fontos, Geza; Juhasz, Eszter D; Szekely, Laszlo; Szelid, Zsolt; Turner, Mark S; Ashrafian, Houman; Frenneaux, Michael P; Andreka, Peter

2007-06-01

Ischaemic preconditioning results in a reduction in ischaemic-reperfusion injury to the heart. This beneficial effect is seen both with direct local preconditioning of the myocardium and with remote preconditioning of easily accessible distant non-vital limb tissue. Ischaemic postconditioning with a comparable sequence of brief periods of local ischaemia, when applied immediately after the ischaemic insult, confers benefits similar to preconditioning. To test the hypothesis that limb ischaemia induces remote postconditioning and hence reduces experimental myocardial infarct size in a validated swine model of acute myocardial infarction. Acute myocardial infarction was induced in 24 pigs with 90 min balloon inflations of the left anterior descending coronary artery. Remote ischaemic postconditioning was induced in 12 of the pigs by four 5 min cycles of blood pressure cuff inflation applied to the lower limb immediately after the balloon deflation. Infarct size was assessed by measuring 72 h creatinine kinase release, MRI scan and immunohistochemical analysis. Area under the curve of creatinine kinase release was significantly reduced in the postconditioning group compared with the control group with a 26% reduction in the infarct size (p<0.05). This was confirmed by MRI scanning and immunohistochemical analysis that revealed a 22% (p<0.05) and a 47.52% (p<0.01) relative reduction in the infarct size, respectively. Remote ischaemic postconditioning is a simple technique to reduce infarct size without the hazards and logistics of multiple coronary artery balloon inflations. This type of conditioning promises clear clinical potential.

Feasibility study of a microprocessor based oculometer system

NASA Technical Reports Server (NTRS)

Varanasi, M. R.

1981-01-01

The elimination of redundancy in data to maximize processing speed and minimize storage requirements were objectives in a feasibility study of a microprocessor based oculometer system that would be portable in size and flexible in use. The appropriate architectural design of the signal processor, improved optics, and the reduction of size, weight, and power to the system were investigated. A flow chart is presented showing the strategy of the design. The simulation for developing microroutines for the high speed algorithmic processor subsystem is discussed as well as the Karhunen-Loeve transform technique for data compression.

The behavior of nanosatellite body materials during electromagnetic launch

NASA Astrophysics Data System (ADS)

Gerasimov, Yu V.; Konstantinova, I. A.; Konstantinova, L. A.; Rakhimov, R. G.; Selivanov, A. B.

2017-11-01

Current development of aerospace technology and demands for the economic feasibility have led to a reduction in weight and size characteristics of the on-board electronics and other on-board equipment. There is a tendency to use small-scale spacecraft: midi-satellites, mini-satellites, nanosatellites etc. Reducing the weight and size characteristics of the satellites makes electromagnetic launching techniques more promising compared to traditional methods of sending payload into orbit. Electromagnetic launch does not require expensive space centers - it is cost-efficient, environmentally friendly and enables frequent low-cost launches.

Optical microtopographic inspection of the surface of tooth subjected to stripping reduction

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Pereira, Pedro B.

2011-05-01

In orthodontics, the decreasing of tooth-size by reducing interproximal enamel surfaces (stripping) of teeth is a common procedure which allows dental alignment with minimal changes in the facial profile and no arch expansion. In order to achieve smooth surfaces, clinicians have been testing various methods and progressively improved this therapeutic technique. In order to evaluate the surface roughness of teeth subject to interproximal reduction through the five most commonly used methods, teeth were inspected by scanning electron microscopy and microtopographically measured using the optical active triangulation based microtopographer MICROTOP.06.MFC. The metrological procedure will be presented as well as the comparative results concluding on the most suitable tooth interproximal reduction method.

Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope.

PubMed

Abellan, Patricia; Parent, Lucas R; Al Hasan, Naila; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M; Evans, James E; Browning, Nigel D

2016-02-16

Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale, such as catalytic activity. In this work, we synthesize Pd nanoparticles with well-controlled size in the sub-3 nm range using scanning transmission electron microscopy (STEM) in combination with an in situ liquid stage. We use an aromatic hydrocarbon (toluene) as a solvent that is very resistant to high-energy electron irradiation, which creates a net reducing environment without the need for additives to scavenge oxidizing radicals. The primary reducing species is molecular hydrogen, which is a widely used reductant in the synthesis of supported metal catalysts. We propose a mechanism of particle formation based on the effect of tri-n-octylphosphine (TOP) on size stabilization, relatively low production of radicals, and autocatalytic reduction of Pd(II) compounds. We combine in situ STEM results with insights from in situ small-angle X-ray scattering (SAXS) from alcohol-based synthesis, having similar reduction potential, in a customized microfluidic device as well as ex situ bulk experiments. This has allowed us to develop a fundamental growth model for the synthesis of size-stabilized Pd nanoparticles and demonstrate the utility of correlating different in situ and ex situ characterization techniques to understand, and ultimately control, metal nanostructure synthesis.

Left Atrial Appendage Closure for Stroke Prevention: Devices, Techniques, and Efficacy.

PubMed

Iskandar, Sandia; Vacek, James; Lavu, Madhav; Lakkireddy, Dhanunjaya

2016-05-01

Left atrial appendage closure can be performed either surgically or percutaneously. Surgical approaches include direct suture, excision and suture, stapling, and clipping. Percutaneous approaches include endocardial, epicardial, and hybrid endocardial-epicardial techniques. Left atrial appendage anatomy is highly variable and complex; therefore, preprocedural imaging is crucial to determine device selection and sizing, which contribute to procedural success and reduction of complications. Currently, the WATCHMAN is the only device that is approved for left atrial appendage closure in the United States. Copyright © 2016 Elsevier Inc. All rights reserved.

An adaptive incremental approach to constructing ensemble classifiers: Application in an information-theoretic computer-aided decision system for detection of masses in mammograms

PubMed Central

Mazurowski, Maciej A.; Zurada, Jacek M.; Tourassi, Georgia D.

2009-01-01

Ensemble classifiers have been shown efficient in multiple applications. In this article, the authors explore the effectiveness of ensemble classifiers in a case-based computer-aided diagnosis system for detection of masses in mammograms. They evaluate two general ways of constructing subclassifiers by resampling of the available development dataset: Random division and random selection. Furthermore, they discuss the problem of selecting the ensemble size and propose two adaptive incremental techniques that automatically select the size for the problem at hand. All the techniques are evaluated with respect to a previously proposed information-theoretic CAD system (IT-CAD). The experimental results show that the examined ensemble techniques provide a statistically significant improvement (AUC=0.905±0.024) in performance as compared to the original IT-CAD system (AUC=0.865±0.029). Some of the techniques allow for a notable reduction in the total number of examples stored in the case base (to 1.3% of the original size), which, in turn, results in lower storage requirements and a shorter response time of the system. Among the methods examined in this article, the two proposed adaptive techniques are by far the most effective for this purpose. Furthermore, the authors provide some discussion and guidance for choosing the ensemble parameters. PMID:19673196

Chemical synthesis and structural characterization of small AuZn nanoparticles

NASA Astrophysics Data System (ADS)

Juárez-Ruiz, E.; Pal, U.; Lombardero-Chartuni, J. A.; Medina, A.; Ascencio, J. A.

2007-03-01

In this paper, we report the aqueous synthesis of bimetallic Au-Zn nanoparticles of different compositions by the simultaneous reduction technique. The stability and atomic configuration of the particles are studied through high-resolution transmission electron microscopy (HRTEM) and UV-Vis optical absorption techniques. Depending on the composition, small bimetallic nanoparticles of 1 15 nm in size were obtained. The average size and size distribution of the bimetallic nanoparticles are seen to be critically dependent on the atomic ratio of the constituting elements Au and Zn. While a 1:1 atomic proportion of Au and Zn produced most stable nanoparticles of smallest average size, nanoparticles produced with higher content of either of the component elements are unstable, inducing agglomeration and coalescence to form elongated structures with uneven morphologies. Au3Zn1 nanoparticles followed a directional growth pattern, producing bimetallic nanorods with multiple crystalline domains. Interestingly, in these rod-like nanostructures, the domains are in well array of solid solution-like bimetallic and pure mono-metallic regions alternatively. Such nanostructures with uneven morphology and compositions might show distinct catalytic selectivity in chemical reactions.

Dissolution enhancement of tadalafil by liquisolid technique.

PubMed

Lu, Mei; Xing, Haonan; Yang, Tianzhi; Yu, Jiankun; Yang, Zhen; Sun, Yanping; Ding, Pingtian

2017-02-01

This study aimed to enhance the dissolution of tadalafil, a poorly water-soluble drug by applying liquisolid technique. The effects of two critical formulation variables, namely drug concentration (17.5% and 35%, w/w) and excipients ratio (10, 15 and 20) on dissolution rates were investigated. Pre-compression tests, including particle size distribution, flowability determination, Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning electron microscopy (SEM), were carried out to investigate the mechanism of dissolution enhancement. Tadalafil liquisolid tablets were prepared and their quality control tests, dissolution study, contact angle measurement, Raman mapping, and storage stability test were performed. The results suggested that all the liquisolid tablets exhibited significantly higher dissolution rates than the conventional tablets and pure tadalafil. FT-IR spectrum reflected no drug-excipient interactions. DSC and XRD studies indicated reduction in crystallinity of tadalafil, which was further confirmed by SEM and Raman mapping outcomes. The contact angle measurement demonstrated obvious increase in wetting property. Taken together, the reduction of particle size and crystallinity, and the improvement of wettability were the main mechanisms for the enhanced dissolution rate. No significant changes were observed in drug crystallinity and dissolution behavior after storage based on XRD, SEM and dissolution results.

Hypergraph Based Feature Selection Technique for Medical Diagnosis.

PubMed

Somu, Nivethitha; Raman, M R Gauthama; Kirthivasan, Kannan; Sriram, V S Shankar

2016-11-01

The impact of internet and information systems across various domains have resulted in substantial generation of multidimensional datasets. The use of data mining and knowledge discovery techniques to extract the original information contained in the multidimensional datasets play a significant role in the exploitation of complete benefit provided by them. The presence of large number of features in the high dimensional datasets incurs high computational cost in terms of computing power and time. Hence, feature selection technique has been commonly used to build robust machine learning models to select a subset of relevant features which projects the maximal information content of the original dataset. In this paper, a novel Rough Set based K - Helly feature selection technique (RSKHT) which hybridize Rough Set Theory (RST) and K - Helly property of hypergraph representation had been designed to identify the optimal feature subset or reduct for medical diagnostic applications. Experiments carried out using the medical datasets from the UCI repository proves the dominance of the RSKHT over other feature selection techniques with respect to the reduct size, classification accuracy and time complexity. The performance of the RSKHT had been validated using WEKA tool, which shows that RSKHT had been computationally attractive and flexible over massive datasets.

Off-resonance suppression for multispectral MR imaging near metallic implants.

PubMed

den Harder, J Chiel; van Yperen, Gert H; Blume, Ulrike A; Bos, Clemens

2015-01-01

Metal artifact reduction in MRI within clinically feasible scan-times without through-plane aliasing. Existing metal artifact reduction techniques include view angle tilting (VAT), which resolves in-plane distortions, and multispectral imaging (MSI) techniques, such as slice encoding for metal artifact correction (SEMAC) and multi-acquisition with variable resonances image combination (MAVRIC), that further reduce image distortions, but significantly increase scan-time. Scan-time depends on anatomy size and anticipated total spectral content of the signal. Signals outside the anticipated spatial region may cause through-plane back-folding. Off-resonance suppression (ORS), using different gradient amplitudes for excitation and refocusing, is proposed to provide well-defined spatial-spectral selectivity in MSI to allow scan-time reduction and flexibility of scan-orientation. Comparisons of MSI techniques with and without ORS were made in phantom and volunteer experiments. Off-resonance suppressed SEMAC (ORS-SEMAC) and outer-region suppressed MAVRIC (ORS-MAVRIC) required limited through-plane phase encoding steps compared with original MSI. Whereas SEMAC (scan time: 5'46") and MAVRIC (4'12") suffered from through-plane aliasing, ORS-SEMAC and ORS-MAVRIC allowed alias-free imaging in the same scan-times. ORS can be used in MSI to limit the selected spatial-spectral region and contribute to metal artifact reduction in clinically feasible scan-times while avoiding slice aliasing. © 2014 Wiley Periodicals, Inc.

Nonlocal nonlinear refractive index of gold nanoparticles synthesized by ascorbic acid reduction: comparison of fitting models.

PubMed

Balbuena Ortega, A; Arroyo Carrasco, M L; Méndez Otero, M M; Gayou, V L; Delgado Macuil, R; Martínez Gutiérrez, H; Iturbe Castillo, M D

2014-12-12

In this paper, the nonlinear refractive index of colloidal gold nanoparticles under continuous wave illumination is investigated with the z -scan technique. Gold nanoparticles were synthesized using ascorbic acid as reductant, phosphates as stabilizer and cetyltrimethylammonium chloride (CTAC) as surfactant agent. The nanoparticle size was controlled with the CTAC concentration. Experiments changing incident power and sample concentration were done. The experimental z -scan results were fitted with three models: thermal lens, aberrant thermal lens and the nonlocal model. It is shown that the nonlocal model reproduces with exceptionally good agreement; the obtained experimental behaviour.

Influence of grain size and sintering temperature grain size on the critical behavior near the paramagnetic to ferromagnetic phase transition temperature in La0.67Sr0.33MnO3 nanoparticles

NASA Astrophysics Data System (ADS)

Baaziz, H.; Tozri, A.; Dhahri, E.; Hlil, E. K.

2018-03-01

We have undertaken a systematic study of critical behavior in La0.67Sr0.33MnO3 nanoparticles, sintered at different temperatures (L6, L8, L10 and L12 sintered at 600 °C, 800 °C, 1000 °C, 1200 °C respectively), by magnetization measurements. The critical exponents are estimated by various techniques such as the Modified Arrott plot, Kouvel-Fisher plot and critical isotherm technique. Compared to standard models, the critical exponents are close to those expected by the Mean-field model (with β = 0.5 γ = 1, and δ = 3) for (L6, L8, and L10) samples and by the (3D) Heisenberg model (β = 0.365, γ = 1.336 and δ = 4.80) for L12 sample. We conclude that the reduction of grain size strongly influences the universality class.

Size-dependent disorder-order transformation in the synthesis of monodisperse intermetallic PdCu nanocatalysts

DOE PAGES

Wang, Chenyu; Chen, Dennis P.; Unocic, Raymond R.; ...

2016-05-23

The high performance of Pd-based intermetallic nanocatalysts has the potential to replace Pt-containing catalysts for fuel-cell reactions. Conventionally, intermetallic particles are obtained through the annealing of nanoparticles of a random alloy distribution. However, this method inevitably leads to sintering of the nanoparticles and generates polydisperse samples. Here, monodisperse PdCu nanoparticles with the ordered B2 phase were synthesized by seed-mediated co-reduction using PdCu nanoparticle seeds with a random alloy distribution (A1 phase). A time-evolution study suggests that the particles must overcome a size-dependent activation barrier for the ordering process to occur. Characterization of the as-prepared PdCu B2 nanoparticles by electron microscopymore » techniques revealed surface segregation of Pd as a thin shell over the PdCu core. The ordered nanoparticles exhibit superior activity and durability for the oxygen reduction reaction in comparison with PdCu A1 nanoparticles. This seed-mediated co-reduction strategy produced monodisperse nanoparticles ideally suited for structure–activity studies. Furthermore, the study of their growth mechanism provides insights into the size dependence of disorder–order transformations of bimetallic alloys at the nanoscale, which should enable the design of synthetic strategies toward other intermetallic systems.« less

Biology Inspired Approach for Communal Behavior in Sensor Networks

NASA Technical Reports Server (NTRS)

Jones, Kennie H.; Lodding, Kenneth N.; Olariu, Stephan; Wilson, Larry; Xin, Chunsheng

2006-01-01

Research in wireless sensor network technology has exploded in the last decade. Promises of complex and ubiquitous control of the physical environment by these networks open avenues for new kinds of science and business. Due to the small size and low cost of sensor devices, visionaries promise systems enabled by deployment of massive numbers of sensors working in concert. Although the reduction in size has been phenomenal it results in severe limitations on the computing, communicating, and power capabilities of these devices. Under these constraints, research efforts have concentrated on developing techniques for performing relatively simple tasks with minimal energy expense assuming some form of centralized control. Unfortunately, centralized control does not scale to massive size networks and execution of simple tasks in sparsely populated networks will not lead to the sophisticated applications predicted. These must be enabled by new techniques dependent on local and autonomous cooperation between sensors to effect global functions. As a step in that direction, in this work we detail a technique whereby a large population of sensors can attain a global goal using only local information and by making only local decisions without any form of centralized control.

The preparation and characterization of novel Pt/C electrocatalysts with controlled porosity and cluster size

DOE PAGES

Coker, Eric N.; Steen, William A.; Miller, Jeffrey T.; ...

2007-05-23

Small platinum clusters have been prepared in zeolite hosts through ion exchange and controlled calcination/reduction processes. In order to enable electrochemical application, the pores of the Pt-zeolite were filled with electrically conductive carbon via infiltration with carbon precursors, polymerization, and pyrolysis. The zeolite host was then removed by acid washing, to leave a Pt/C electrocatalyst possessing quasi-zeolitic porosity and Pt clusters of well-controlled size. The electrocatalysts were characterized by TEM, XRD, EXAFS, nitrogen adsorption and electrochemical techniques. Depending on the synthesis conditions, average Pt cluster sizes in the Pt/C catalysts ranged from 1.3 to 2.0 nm. The presence of orderedmore » porosity/structure in the catalysts was evident in TEM images as lattice fringes, and in XRD as a low-angle diffraction peak with d-spacing similar to the parent zeolite. The catalysts possess micro- and meso-porosity, with pore size distributions that depend upon synthesis variables. Finally, electroactive surface areas as high as 112 m 2 g Pt -1 have been achieved in Pt/C electrocatalysts which show oxygen reduction performance comparable to standard industrial catalysts.« less

Click polymerization for the synthesis of reduction-responsive polymeric prodrug

NASA Astrophysics Data System (ADS)

Zhang, Xiaojin; Wang, Hongquan; Dai, Yu

2018-05-01

Click polymerization is a powerful polymerization technique for the construction of new macromolecules with well-defined structures and multifaceted functionalities. Here, we synthesize reduction-responsive polymeric prodrug PEG- b-(PSS- g-MTX)- b-PEG containing disulfide bonds and pendant methotrexate (MTX) via two-step click polymerization followed by conjugating MTX to pendant hydroxyl. MTX content in polymeric prodrug is 13.5%. Polymeric prodrug is able to form polymeric micelles by self-assembly in aqueous solution. Polymeric micelles are spherical nanoparticles with tens of nanometers in size. Of note, polymeric micelles are reduction-responsive due to disulfide bonds in the backbone of PEG- b-(PSS- g-MTX)- b-PEG and could release pendant drugs in the presence of the reducing agents such as dl-dithiothreitol (DTT).

Provably secure identity-based identification and signature schemes from code assumptions

PubMed Central

Zhao, Yiming

2017-01-01

Code-based cryptography is one of few alternatives supposed to be secure in a post-quantum world. Meanwhile, identity-based identification and signature (IBI/IBS) schemes are two of the most fundamental cryptographic primitives, so several code-based IBI/IBS schemes have been proposed. However, with increasingly profound researches on coding theory, the security reduction and efficiency of such schemes have been invalidated and challenged. In this paper, we construct provably secure IBI/IBS schemes from code assumptions against impersonation under active and concurrent attacks through a provably secure code-based signature technique proposed by Preetha, Vasant and Rangan (PVR signature), and a security enhancement Or-proof technique. We also present the parallel-PVR technique to decrease parameter values while maintaining the standard security level. Compared to other code-based IBI/IBS schemes, our schemes achieve not only preferable public parameter size, private key size, communication cost and signature length due to better parameter choices, but also provably secure. PMID:28809940

Provably secure identity-based identification and signature schemes from code assumptions.

PubMed

Song, Bo; Zhao, Yiming

2017-01-01

Code-based cryptography is one of few alternatives supposed to be secure in a post-quantum world. Meanwhile, identity-based identification and signature (IBI/IBS) schemes are two of the most fundamental cryptographic primitives, so several code-based IBI/IBS schemes have been proposed. However, with increasingly profound researches on coding theory, the security reduction and efficiency of such schemes have been invalidated and challenged. In this paper, we construct provably secure IBI/IBS schemes from code assumptions against impersonation under active and concurrent attacks through a provably secure code-based signature technique proposed by Preetha, Vasant and Rangan (PVR signature), and a security enhancement Or-proof technique. We also present the parallel-PVR technique to decrease parameter values while maintaining the standard security level. Compared to other code-based IBI/IBS schemes, our schemes achieve not only preferable public parameter size, private key size, communication cost and signature length due to better parameter choices, but also provably secure.

Remote ischaemic postconditioning protects the heart during acute myocardial infarction in pigs

PubMed Central

Andreka, Gyorgy; Vertesaljai, Marton; Szantho, Gergely; Font, Gusztav; Piroth, Zsolt; Fontos, Geza; Juhasz, Eszter D; Szekely, Laszlo; Szelid, Zsolt; Turner, Mark S; Ashrafian, Houman; Frenneaux, Michael P

2007-01-01

Background Ischaemic preconditioning results in a reduction in ischaemic‐reperfusion injury to the heart. This beneficial effect is seen both with direct local preconditioning of the myocardium and with remote preconditioning of easily accessible distant non‐vital limb tissue. Ischaemic postconditioning with a comparable sequence of brief periods of local ischaemia, when applied immediately after the ischaemic insult, confers benefits similar to preconditioning. Objective To test the hypothesis that limb ischaemia induces remote postconditioning and hence reduces experimental myocardial infarct size in a validated swine model of acute myocardial infarction. Methods Acute myocardial infarction was induced in 24 pigs with 90 min balloon inflations of the left anterior descending coronary artery. Remote ischaemic postconditioning was induced in 12 of the pigs by four 5 min cycles of blood pressure cuff inflation applied to the lower limb immediately after the balloon deflation. Infarct size was assessed by measuring 72 h creatinine kinase release, MRI scan and immunohistochemical analysis. Results Area under the curve of creatinine kinase release was significantly reduced in the postconditioning group compared with the control group with a 26% reduction in the infarct size (p<0.05). This was confirmed by MRI scanning and immunohistochemical analysis that revealed a 22% (p<0.05) and a 47.52% (p<0.01) relative reduction in the infarct size, respectively. Conclusion Remote ischaemic postconditioning is a simple technique to reduce infarct size without the hazards and logistics of multiple coronary artery balloon inflations. This type of conditioning promises clear clinical potential. PMID:17449499

Investigation of thermal conduction in symmetric and asymmetric nanoporous structures

NASA Astrophysics Data System (ADS)

Yu, Ziqi; Ferrer-Argemi, Laia; Lee, Jaeho

2017-12-01

Nanoporous structures with a critical dimension comparable to or smaller than the phonon mean free path have demonstrated significant thermal conductivity reductions that are attractive for thermoelectric applications, but the presence of various geometric parameters complicates the understanding of governing mechanisms. Here, we use a ray tracing technique to investigate phonon boundary scattering phenomena in Si nanoporous structures of varying pore shapes, pore alignments, and pore size distributions, and identify mechanisms that are primarily responsible for thermal conductivity reductions. Our simulation results show that the neck size, or the smallest distance between nearest pores, is the key parameter in understanding nanoporous structures of varying pore shapes and the same porosities. When the neck size and the porosity are both identical, asymmetric pore shapes provide a lower thermal conductivity compared with symmetric pore shapes, due to localized heat fluxes. Asymmetric nanoporous structures show possibilities of realizing thermal rectification even with fully diffuse surface boundaries, in which optimal arrangements of triangular pores show a rectification ratio up to 13 when the injection angles are optimally controlled. For symmetric nanoporous structures, hexagonal-lattice pores achieve larger thermal conductivity reductions than square-lattice pores due to the limited line of sight for phonons. We also show that nanoporous structures of alternating pore size distributions from large to small pores yield a lower thermal conductivity compared with those of uniform pore size distributions in the given porosity. These findings advance the understanding of phonon boundary scattering phenomena in complex geometries and enable optimal designs of artificial nanostructures for thermoelectric energy harvesting and solid-state cooling systems.

Preconditioned conjugate gradient technique for the analysis of symmetric anisotropic structures

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Peters, Jeanne M.

1987-01-01

An efficient preconditioned conjugate gradient (PCG) technique and a computational procedure are presented for the analysis of symmetric anisotropic structures. The technique is based on selecting the preconditioning matrix as the orthotropic part of the global stiffness matrix of the structure, with all the nonorthotropic terms set equal to zero. This particular choice of the preconditioning matrix results in reducing the size of the analysis model of the anisotropic structure to that of the corresponding orthotropic structure. The similarities between the proposed PCG technique and a reduction technique previously presented by the authors are identified and exploited to generate from the PCG technique direct measures for the sensitivity of the different response quantities to the nonorthotropic (anisotropic) material coefficients of the structure. The effectiveness of the PCG technique is demonstrated by means of a numerical example of an anisotropic cylindrical panel.

Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

NASA Astrophysics Data System (ADS)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Design of a practical model-observer-based image quality assessment method for x-ray computed tomography imaging systems

PubMed Central

Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.

2016-01-01

Abstract. The use of a channelization mechanism on model observers not only makes mimicking human visual behavior possible, but also reduces the amount of image data needed to estimate the model observer parameters. The channelized Hotelling observer (CHO) and channelized scanning linear observer (CSLO) have recently been used to assess CT image quality for detection tasks and combined detection/estimation tasks, respectively. Although the use of channels substantially reduces the amount of data required to compute image quality, the number of scans required for CT imaging is still not practical for routine use. It is our desire to further reduce the number of scans required to make CHO or CSLO an image quality tool for routine and frequent system validations and evaluations. This work explores different data-reduction schemes and designs an approach that requires only a few CT scans. Three different kinds of approaches are included in this study: a conventional CHO/CSLO technique with a large sample size, a conventional CHO/CSLO technique with fewer samples, and an approach that we will show requires fewer samples to mimic conventional performance with a large sample size. The mean value and standard deviation of areas under ROC/EROC curve were estimated using the well-validated shuffle approach. The results indicate that an 80% data reduction can be achieved without loss of accuracy. This substantial data reduction is a step toward a practical tool for routine-task-based QA/QC CT system assessment. PMID:27493982

Complete magnesiothermic reduction reaction of vertically aligned mesoporous silica channels to form pure silicon nanoparticles

PubMed Central

Kim, Kyoung Hwan; Lee, Dong Jin; Cho, Kyeong Min; Kim, Seon Joon; Park, Jung-Ki; Jung, Hee-Tae

2015-01-01

Owing to its simplicity and low temperature conditions, magnesiothermic reduction of silica is one of the most powerful methods for producing silicon nanostructures. However, incomplete reduction takes place in this process leaving unconverted silica under the silicon layer. This phenomenon limits the use of this method for the rational design of silicon structures. In this effort, a technique that enables complete magnesiothermic reduction of silica to form silicon has been developed. The procedure involves magnesium promoted reduction of vertically oriented mesoporous silica channels on reduced graphene oxides (rGO) sheets. The mesopores play a significant role in effectively enabling magnesium gas to interact with silica through a large number of reaction sites. Utilizing this approach, highly uniform, ca. 10 nm sized silicon nanoparticles are generated without contamination by unreacted silica. The new method for complete magnesiothermic reduction of mesoporous silica approach provides a foundation for the rational design of silicon structures. PMID:25757800

Miniaturized dielectric waveguide filters

NASA Astrophysics Data System (ADS)

Sandhu, Muhammad Y.; Hunter, Ian C.

2016-10-01

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.

Integrating dimension reduction and out-of-sample extension in automated classification of ex vivo human patellar cartilage on phase contrast X-ray computed tomography.

PubMed

Nagarajan, Mahesh B; Coan, Paola; Huber, Markus B; Diemoz, Paul C; Wismüller, Axel

2015-01-01

Phase contrast X-ray computed tomography (PCI-CT) has been demonstrated as a novel imaging technique that can visualize human cartilage with high spatial resolution and soft tissue contrast. Different textural approaches have been previously investigated for characterizing chondrocyte organization on PCI-CT to enable classification of healthy and osteoarthritic cartilage. However, the large size of feature sets extracted in such studies motivates an investigation into algorithmic feature reduction for computing efficient feature representations without compromising their discriminatory power. For this purpose, geometrical feature sets derived from the scaling index method (SIM) were extracted from 1392 volumes of interest (VOI) annotated on PCI-CT images of ex vivo human patellar cartilage specimens. The extracted feature sets were subject to linear and non-linear dimension reduction techniques as well as feature selection based on evaluation of mutual information criteria. The reduced feature set was subsequently used in a machine learning task with support vector regression to classify VOIs as healthy or osteoarthritic; classification performance was evaluated using the area under the receiver-operating characteristic (ROC) curve (AUC). Our results show that the classification performance achieved by 9-D SIM-derived geometric feature sets (AUC: 0.96 ± 0.02) can be maintained with 2-D representations computed from both dimension reduction and feature selection (AUC values as high as 0.97 ± 0.02). Thus, such feature reduction techniques can offer a high degree of compaction to large feature sets extracted from PCI-CT images while maintaining their ability to characterize the underlying chondrocyte patterns.

Spatial Angular Compounding Technique for H-Scan Ultrasound Imaging.

PubMed

Khairalseed, Mawia; Xiong, Fangyuan; Kim, Jung-Whan; Mattrey, Robert F; Parker, Kevin J; Hoyt, Kenneth

2018-01-01

H-Scan is a new ultrasound imaging technique that relies on matching a model of pulse-echo formation to the mathematics of a class of Gaussian-weighted Hermite polynomials. This technique may be beneficial in the measurement of relative scatterer sizes and in cancer therapy, particularly for early response to drug treatment. Because current H-scan techniques use focused ultrasound data acquisitions, spatial resolution degrades away from the focal region and inherently affects relative scatterer size estimation. Although the resolution of ultrasound plane wave imaging can be inferior to that of traditional focused ultrasound approaches, the former exhibits a homogeneous spatial resolution throughout the image plane. The purpose of this study was to implement H-scan using plane wave imaging and investigate the impact of spatial angular compounding on H-scan image quality. Parallel convolution filters using two different Gaussian-weighted Hermite polynomials that describe ultrasound scattering events are applied to the radiofrequency data. The H-scan processing is done on each radiofrequency image plane before averaging to get the angular compounded image. The relative strength from each convolution is color-coded to represent relative scatterer size. Given results from a series of phantom materials, H-scan imaging with spatial angular compounding more accurately reflects the true scatterer size caused by reductions in the system point spread function and improved signal-to-noise ratio. Preliminary in vivo H-scan imaging of tumor-bearing animals suggests this modality may be useful for monitoring early response to chemotherapeutic treatment. Overall, H-scan imaging using ultrasound plane waves and spatial angular compounding is a promising approach for visualizing the relative size and distribution of acoustic scattering sources. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

Polyethylene glycol (PEG) assisted size-controlled SnO{sub 2} nanoparticles by sol-gel process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, P., E-mail: ptrip71@yahoo.com; Ahmed, Ateeq; Ali, Tinku

2016-05-23

Tetragonal phase tin oxide (SnO{sub 2}) nanoparticles have been synthesized by sol–gel method using SnCl{sub 4}.5H{sub 2}O and polyethylene glycol (PEG) of different concentration. The phase, size and purity of the final products are characterized by X-ray diffraction (XRD). The morphology is confirmed by scanning electron microscopy (SEM) analysis. There exists relationship between the concentration of PEG and particle size of SnO{sub 2} nanoparticles. Increase in concentration of PEG caused the reduction of particle size of tin oxide nanoparticles. The results suggest that the concentration of PEG plays a significant role in determining the size of SnO{sub 2} nanoparticles synthesizedmore » via this method. The optical property of the product has been explored by Ultraviolet (UV-visible) and Fourier Transform Infrared (FTIR) spectroscopic techniques.« less

Monocrystalline solar cells performance coated by silver nanoparticles: Effect of NPs sizes from point of view Mie theory

NASA Astrophysics Data System (ADS)

Elnoby, Rasha M.; Mourad, M. Hussein; Elnaby, Salah L. Hassab; Abou Kana, Maram T. H.

2018-05-01

Solar based cells coated by nanoparticles (NPs) acknowledge potential utilizing as a part of photovoltaic innovation. The acquired silicon solar cells (Si-SCs) coated with different sizes of silver nanoparticles (Ag NPs) as well as uncoated were fabricated in our lab. The sizes and optical properties of prepared NPs were characterized by spectroscopic techniques and Mie theory respectively. The reflectivity of Si-SCs showed reduction of this property as the size of NPs increased. Electrical properties as open circuit current, fill factor and output power density were assessed and discussed depending on point of view of Mie theory for the optical properties of NPs. Also, photostabilities of SCs were assessed using diode laser of wavelength 450 nm and power 300 mW. Coated SCs with the largest Ag NPs size showed the highest Photostability due to its highest scattering efficiency according to Mie theory concept.

An overview of the sustainability of solid waste management at military installations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borglin, S.; Shore, J.; Worden, H.

2009-08-15

Sustainable municipal solid waste management at military solutions necessitates a combined approach that includes waste reduction, alternative disposal techniques, and increased recycling. Military installations are unique because they often represent large employers in the region in which they are located, thereby making any practices they employ impact overall waste management strategies of the region. Solutions for waste sustainability will be dependent on operational directives and base location, availability of resources such as water and energy, and size of population. Presented in this paper are descriptions of available waste strategies that can be used to support sustainable waste management. Results presentedmore » indicate source reduction and recycling to be the most sustainable solutions. However, new waste-to-energy plants and composting have potential to improve on these well proven techniques and allow military installations to achieve sustainable waste management.« less

Arthroscopic fixation of the clavicle shaft fracture.

PubMed

Kim, Yang-Soo; Lee, Hyo-Jin; Kim, Jong-Ick; Yang, Hyo; Jin, Hong-Ki; Patel, Hiren Kirtibhai; Kim, Jong-Ho; Park, In

2017-01-01

This article describes an arthroscopic technique for the fixation of clavicle shaft fractures. A viewing portal is made 2 cm anterior to the fracture site, and a working portal is made 2 cm lateral to the fracture site. The guide wire for a 4.0-mm cannulated screw is inserted through the fracture site to the medial fracture fragment under arthroscopic guidance. Through the medial fragment, the guide wire is delivered through the skin anteriorly. The fracture is reduced, and then, the guide wire is drilled back across the fracture site to the lateral fracture fragment. After confirming the reduction under arthroscopy, the appropriately sized cannulated screw is inserted after reaming. This arthroscopic technique would be useful for the precise reduction and minimal invasive fixation of clavicle shaft fractures. Preliminary results are encouraging, and further studies with long-term follow-up are needed to determine the precise indications and limitations of the procedure.

Multi-Level Reduced Order Modeling Equipped with Probabilistic Error Bounds

NASA Astrophysics Data System (ADS)

Abdo, Mohammad Gamal Mohammad Mostafa

This thesis develops robust reduced order modeling (ROM) techniques to achieve the needed efficiency to render feasible the use of high fidelity tools for routine engineering analyses. Markedly different from the state-of-the-art ROM techniques, our work focuses only on techniques which can quantify the credibility of the reduction which can be measured with the reduction errors upper-bounded for the envisaged range of ROM model application. Our objective is two-fold. First, further developments of ROM techniques are proposed when conventional ROM techniques are too taxing to be computationally practical. This is achieved via a multi-level ROM methodology designed to take advantage of the multi-scale modeling strategy typically employed for computationally taxing models such as those associated with the modeling of nuclear reactor behavior. Second, the discrepancies between the original model and ROM model predictions over the full range of model application conditions are upper-bounded in a probabilistic sense with high probability. ROM techniques may be classified into two broad categories: surrogate construction techniques and dimensionality reduction techniques, with the latter being the primary focus of this work. We focus on dimensionality reduction, because it offers a rigorous approach by which reduction errors can be quantified via upper-bounds that are met in a probabilistic sense. Surrogate techniques typically rely on fitting a parametric model form to the original model at a number of training points, with the residual of the fit taken as a measure of the prediction accuracy of the surrogate. This approach, however, does not generally guarantee that the surrogate model predictions at points not included in the training process will be bound by the error estimated from the fitting residual. Dimensionality reduction techniques however employ a different philosophy to render the reduction, wherein randomized snapshots of the model variables, such as the model parameters, responses, or state variables, are projected onto lower dimensional subspaces, referred to as the "active subspaces", which are selected to capture a user-defined portion of the snapshots variations. Once determined, the ROM model application involves constraining the variables to the active subspaces. In doing so, the contribution from the variables discarded components can be estimated using a fundamental theorem from random matrix theory which has its roots in Dixon's theory, developed in 1983. This theory was initially presented for linear matrix operators. The thesis extends this theorem's results to allow reduction of general smooth nonlinear operators. The result is an approach by which the adequacy of a given active subspace determined using a given set of snapshots, generated either using the full high fidelity model, or other models with lower fidelity, can be assessed, which provides insight to the analyst on the type of snapshots required to reach a reduction that can satisfy user-defined preset tolerance limits on the reduction errors. Reactor physics calculations are employed as a test bed for the proposed developments. The focus will be on reducing the effective dimensionality of the various data streams such as the cross-section data and the neutron flux. The developed methods will be applied to representative assembly level calculations, where the size of the cross-section and flux spaces are typically large, as required by downstream core calculations, in order to capture the broad range of conditions expected during reactor operation. (Abstract shortened by ProQuest.).

Decrystallization of Crystals Using Gold “Nano-Bullets” and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

PubMed Central

Thompson, Nishone; Boone-Kukoyi, Zainab; Shortt, Raquel; Lansiquot, Carisse; Kioko, Bridgit; Bonyi, Enock; Toker, Salih; Ozturk, Birol; Aslan, Kadir

2017-01-01

Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as “nano-bullets” to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10–100 μm) and L-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and L-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout. PMID:27763557

Determination of Natural 14C Abundances in Dissolved Organic Carbon in Organic-Rich Marine Sediment Porewaters by Thermal Sulfate Reduction

NASA Astrophysics Data System (ADS)

Johnson, L.; Komada, T.

2010-12-01

The abundances of natural 14C in dissolved organic carbon (DOC) in the marine environment hold clues regarding the processes that influence the biogeochemical cycling of this large carbon reservoir. At present, UV irradiation is the widely accepted method for oxidizing seawater DOC for determination of their 14C abundances. This technique yields precise and accurate values with low blanks, but it requires a dedicated vacuum line, and hence can be difficult to implement. As an alternative technique that can be conducted on a standard preparatory vacuum line, we modified and tested a thermal sulfate reduction method that was previously developed to determine δ13C values of marine DOC (Fry B. et al., 1996. Analysis of marine DOC using a dry combustion method. Mar. Chem., 54: 191-201.) to determine the 14C abundances of DOC in marine sediment porewaters. In this method, the sample is dried in a 100 ml round-bottom Pyrex flask in the presence of excess oxidant (K2SO4) and acid (H3PO4), and combusted at 550 deg.C. The combustion products are cryogenically processed to collect and quantify CO2 using standard procedures. Materials we have oxidized to date range from 6-24 ml in volume, and 95-1500 μgC in size. The oxidation efficiency of this method was tested by processing known amounts of reagent-grade dextrose and sucrose (as examples of labile organic matter), tannic acid and humic acid (as examples of complex natural organic matter), and porewater DOC extracted from organic-rich nearshore sediments. The carbon yields for all of these materials averaged 99±4% (n=18). The 14C abundances of standard materials IAEA C-6 and IAEA C-5 processed by this method using >1mgC aliquots were within error of certified values. The size and the isotopic value of the blank were determined by a standard dilution technique using IAEA C-6 and IAEA C-5 that ranged in size from 150 to 1500 μgC (n=4 and 2, respectively). This yielded a blank size of 6.7±0.7 μgC, and a blank isotopic value of 0.54±0.05 fMC. The size of the blank agreed well with that determined directly by processing variable volumes of UV-irradiated deionized water (5.6±0.7 μgC, n=9). The size of the blank amounts to <~5% of the size of porewater DOC samples that are typically recovered from organic-rich sediment cores (~100-500 μgC). The fMC value of the blank suggests that there may be multiple sources of extraneous carbon that range in 14C abundance. In order to assess the fidelity of 14C abundances in natural porewater DOC oxidized by thermal sulfate reduction, we oxidized porewater DOC samples collected from the central floor of the Santa Monica Basin, California Borderland, using both this method and UV irradiation (the latter carried out at the Druffel laboratory, University of California Irvine). The fMC values obtained by the two methods agreed within error. Carbon yields from the two methods also agreed closely. These findings show that thermal sulfate reduction may be a promising method to oxidize small, concentrated marine DOC samples for 14C analysis.

Reduction of glycine particle size by impinging jet crystallization.

PubMed

Tari, Tímea; Fekete, Zoltán; Szabó-Révész, Piroska; Aigner, Zoltán

2015-01-15

The parameters of crystallization processes determine the habit and particle size distribution of the products. A narrow particle size distribution and a small average particle size are crucial for the bioavailability of poorly water-soluble pharmacons. Thus, particle size reduction is often required during crystallization processes. Impinging jet crystallization is a method that results in a product with a reduced particle size due to the homogeneous and high degree of supersaturation at the impingement point. In this work, the applicability of the impinging jet technique as a new approach in crystallization was investigated for the antisolvent crystallization of glycine. A factorial design was applied to choose the relevant crystallization factors. The results were analysed by means of a statistical program. The particle size distribution of the crystallized products was investigated with a laser diffraction particle size analyser. The roundness and morphology were determined with the use of a light microscopic image analysis system and a scanning electron microscope. Polymorphism was characterized by differential scanning calorimetry and powder X-ray diffraction. Headspace gas chromatography was utilized to determine the residual solvent content. Impinging jet crystallization proved to reduce the particle size of glycine. The particle size distribution was appropriate, and the average particle size was an order of magnitude smaller (d(0.5)=8-35 μm) than that achieved with conventional crystallization (d(0.5)=82-680 μm). The polymorphic forms of the products were influenced by the solvent ratio. The quantity of residual solvent in the crystallized products was in compliance with the requirements of the International Conference on Harmonization. Copyright © 2014 Elsevier B.V. All rights reserved.

Umbilical cord sparing technique for repair of congenital hernia into the cord and small omphalocele.

PubMed

Ceccanti, Silvia; Falconi, Ilaria; Frediani, Simone; Boscarelli, Alessandro; Musleh, Layla; Cozzi, Denis A

2017-01-01

Current repair of small omphaloceles and hernias into the umbilical cord is a straightforward procedure, whose repair may result in a suboptimal cosmetic outcome. We describe a novel repair technique retaining the umbilical cord elements in an attempt to improve the cosmetic appearance of the umbilicus. Eight neonates were consecutively treated more than a ten-year period. Size of the fascial defects ranged 1 to 3cm (median, 2). Present technique entails incision of the amniotic sac without its detachment from the skin, reduction of the extruded contents under direct vision, and closure of the abdominal wall defect by circumferential suturing of peritoneum and fascia around the base of the amniotic sac. The amniotic sac is then re-approximated and folded to create an umbilical stump, which is trimmed and left to shed naturally. All patients achieved a scarless abdomen with a normal appearing umbilicus in 6. The remaining 2 patients are awaiting surgery for persisting umbilical hernia repair and umbilicoplasty, respectively. Poor esthetic outcome was significantly associated with initial fascial defect ≥2.5cm in size (p=0.03). Present technique is a simple and cosmetically appealing repair for umbilical cord hernias and small omphaloceles, especially effective when the size of the fascial defect is less than 2.5cm. IV (Treatment Study). Copyright © 2017 Elsevier Inc. All rights reserved.

A Third-Generation Adaptive Statistical Iterative Reconstruction Technique: Phantom Study of Image Noise, Spatial Resolution, Lesion Detectability, and Dose Reduction Potential.

PubMed

Euler, André; Solomon, Justin; Marin, Daniele; Nelson, Rendon C; Samei, Ehsan

2018-06-01

The purpose of this study was to assess image noise, spatial resolution, lesion detectability, and the dose reduction potential of a proprietary third-generation adaptive statistical iterative reconstruction (ASIR-V) technique. A phantom representing five different body sizes (12-37 cm) and a contrast-detail phantom containing lesions of five low-contrast levels (5-20 HU) and three sizes (2-6 mm) were deployed. Both phantoms were scanned on a 256-MDCT scanner at six different radiation doses (1.25-10 mGy). Images were reconstructed with filtered back projection (FBP), ASIR-V with 50% blending with FBP (ASIR-V 50%), and ASIR-V without blending (ASIR-V 100%). In the first phantom, noise properties were assessed by noise power spectrum analysis. Spatial resolution properties were measured by use of task transfer functions for objects of different contrasts. Noise magnitude, noise texture, and resolution were compared between the three groups. In the second phantom, low-contrast detectability was assessed by nine human readers independently for each condition. The dose reduction potential of ASIR-V was estimated on the basis of a generalized linear statistical regression model. On average, image noise was reduced 37.3% with ASIR-V 50% and 71.5% with ASIR-V 100% compared with FBP. ASIR-V shifted the noise power spectrum toward lower frequencies compared with FBP. The spatial resolution of ASIR-V was equivalent or slightly superior to that of FBP, except for the low-contrast object, which had lower resolution. Lesion detection significantly increased with both ASIR-V levels (p = 0.001), with an estimated radiation dose reduction potential of 15% ± 5% (SD) for ASIR-V 50% and 31% ± 9% for ASIR-V 100%. ASIR-V reduced image noise and improved lesion detection compared with FBP and had potential for radiation dose reduction while preserving low-contrast detectability.

Integrative sparse principal component analysis of gene expression data.

PubMed

Liu, Mengque; Fan, Xinyan; Fang, Kuangnan; Zhang, Qingzhao; Ma, Shuangge

2017-12-01

In the analysis of gene expression data, dimension reduction techniques have been extensively adopted. The most popular one is perhaps the PCA (principal component analysis). To generate more reliable and more interpretable results, the SPCA (sparse PCA) technique has been developed. With the "small sample size, high dimensionality" characteristic of gene expression data, the analysis results generated from a single dataset are often unsatisfactory. Under contexts other than dimension reduction, integrative analysis techniques, which jointly analyze the raw data of multiple independent datasets, have been developed and shown to outperform "classic" meta-analysis and other multidatasets techniques and single-dataset analysis. In this study, we conduct integrative analysis by developing the iSPCA (integrative SPCA) method. iSPCA achieves the selection and estimation of sparse loadings using a group penalty. To take advantage of the similarity across datasets and generate more accurate results, we further impose contrasted penalties. Different penalties are proposed to accommodate different data conditions. Extensive simulations show that iSPCA outperforms the alternatives under a wide spectrum of settings. The analysis of breast cancer and pancreatic cancer data further shows iSPCA's satisfactory performance. © 2017 WILEY PERIODICALS, INC.

Design of Miniaturized Double-Negative Material for Specific Absorption Rate Reduction in Human Head

PubMed Central

Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

2014-01-01

In this study, a double-negative triangular metamaterial (TMM) structure, which exhibits a resounding electric response at microwave frequency, was developed by etching two concentric triangular rings of conducting materials. A finite-difference time-domain method in conjunction with the lossy-Drude model was used in this study. Simulations were performed using the CST Microwave Studio. The specific absorption rate (SAR) reduction technique is discussed, and the effects of the position of attachment, the distance, and the size of the metamaterials on the SAR reduction are explored. The performance of the double-negative TMMs in cellular phones was also measured in the cheek and the tilted positions using the COMOSAR system. The TMMs achieved a 52.28% reduction for the 10 g SAR. These results provide a guideline to determine the triangular design of metamaterials with the maximum SAR reducing effect for a mobile phone. PMID:25350398

Design of miniaturized double-negative material for specific absorption rate reduction in human head.

PubMed

Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

2014-01-01

In this study, a double-negative triangular metamaterial (TMM) structure, which exhibits a resounding electric response at microwave frequency, was developed by etching two concentric triangular rings of conducting materials. A finite-difference time-domain method in conjunction with the lossy-Drude model was used in this study. Simulations were performed using the CST Microwave Studio. The specific absorption rate (SAR) reduction technique is discussed, and the effects of the position of attachment, the distance, and the size of the metamaterials on the SAR reduction are explored. The performance of the double-negative TMMs in cellular phones was also measured in the cheek and the tilted positions using the COMOSAR system. The TMMs achieved a 52.28% reduction for the 10 g SAR. These results provide a guideline to determine the triangular design of metamaterials with the maximum SAR reducing effect for a mobile phone.

Physical pretreatment – woody biomass size reduction – for forest biorefinery

Treesearch

J.Y. Zhu

2011-01-01

Physical pretreatment of woody biomass or wood size reduction is a prerequisite step for further chemical or biochemical processing in forest biorefinery. However, wood size reduction is very energy intensive which differentiates woody biomass from herbaceous biomass for biorefinery. This chapter discusses several critical issues related to wood size reduction: (1)...

The Synergy of Class Size Reduction and Classroom Quality

ERIC Educational Resources Information Center

Graue, Elizabeth; Rauscher, Erica; Sherfinski, Melissa

2009-01-01

A contextual approach to understanding class size reduction includes attention to both educational inputs and processes. Based on our study of a class size reduction program in Wisconsin we explore the following question: How do class size reduction and classroom quality interact to produce learning opportunities in early elementary classrooms? To…

Volume reduction of benign thyroid nodules 3 months after a single treatment with high-intensity focused ultrasound (HIFU).

PubMed

Korkusuz, Huedayi; Fehre, Niklas; Sennert, Michael; Happel, Christian; Grünwald, Frank

2015-01-01

High-intensity focused ultrasound (HIFU) is a promising, non-invasive technique in treating benign thyroid nodules (TNs). The aim of this study was to evaluate the efficacy of HIFU to induce clinically meaningful shrinkage in benign predominantly solid TNs and to identify variables that influence or predict the magnitude of TN volume reduction. For each of ten subjects, HIFU treatment was conducted on a single nodule. Nodular volume was measured sonographically at baseline and at 3 months post-procedure. Nodular function and early treatment assessment was done scintigraphically. Median nodular volume reduction was 0.7 ml absolute and 48.8% relative to pre-interventional size (p < 0.05). Absolute shrinkage was negatively correlated with the average treatment depth (τ = -0.61, p < 0.05). Absolute nodular volume was positively correlated with the scintigraphic nodular uptake reduction (τ = 0.66, p < 0.05). HIFU treatment of benign predominantly solid TNs appears to be safe and effective for inducing nodular shrinkage. Despite potential for improvement, a single treatment session with HIFU is already a viable alternative to more standard methods. The feasibility of multiple HIFU treatments requires further investigation. Due to the small sample size, the findings of this analysis need conformation by larger studies.

Reactive impinging-flow technique for polymer-electrolyte-fuel-cell electrode-defect detection

DOE PAGES

Zenyuk, Iryna V.; Englund, Nicholas; Bender, Guido; ...

2016-09-29

Reactive impinging flow (RIF) is a novel quality-control method for defect detection (i.e., reduction in Pt catalyst loading) in gas-diffusion electrodes (GDEs) on weblines. The technique uses infrared thermography to detect temperature of a nonflammable (<4% H 2) reactive mixture of H 2/O 2 in N 2 impinging and reacting on a Pt catalytic surface. In this article, different GDE size defects (with catalyst-loading reductions of 25, 50, and 100%) are detected at various webline speeds (3.048 and 9.144 m min -1) and gas flowrates (32.5 or 50 standard L min -1). Furthermore, a model is developed and validated formore » the technique, and it is subsequently used to optimize operating conditions and explore the applicability of the technique to a range of defects. The model suggests that increased detection can be achieved by recting more of the impinging H 2, which can be accomplished by placing blocking substrates on the top, bottom, or both of the GDE; placing a substrate on both results in a factor of four increase in the temperature differential, which is needed for smaller defect detection. Lastly, overall, the RIF technique is shown to be a promising route for in-line, high-speed, large-area detection of GDE defects on moving weblines.« less

Reactive impinging-flow technique for polymer-electrolyte-fuel-cell electrode-defect detection

NASA Astrophysics Data System (ADS)

Zenyuk, Iryna V.; Englund, Nicholas; Bender, Guido; Weber, Adam Z.; Ulsh, Michael

2016-11-01

Reactive impinging flow (RIF) is a novel quality-control method for defect detection (i.e., reduction in Pt catalyst loading) in gas-diffusion electrodes (GDEs) on weblines. The technique uses infrared thermography to detect temperature of a nonflammable (<4% H2) reactive mixture of H2/O2 in N2 impinging and reacting on a Pt catalytic surface. In this paper, different GDE size defects (with catalyst-loading reductions of 25, 50, and 100%) are detected at various webline speeds (3.048 and 9.144 m min-1) and gas flowrates (32.5 or 50 standard L min-1). Furthermore, a model is developed and validated for the technique, and it is subsequently used to optimize operating conditions and explore the applicability of the technique to a range of defects. The model suggests that increased detection can be achieved by recting more of the impinging H2, which can be accomplished by placing blocking substrates on the top, bottom, or both of the GDE; placing a substrate on both results in a factor of four increase in the temperature differential, which is needed for smaller defect detection. Overall, the RIF technique is shown to be a promising route for in-line, high-speed, large-area detection of GDE defects on moving weblines.

Using machine learning techniques to automate sky survey catalog generation

NASA Technical Reports Server (NTRS)

Fayyad, Usama M.; Roden, J. C.; Doyle, R. J.; Weir, Nicholas; Djorgovski, S. G.

1993-01-01

We describe the application of machine classification techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Palomar Observatory Sky Survey provides comprehensive photographic coverage of the northern celestial hemisphere. The photographic plates are being digitized into images containing on the order of 10(exp 7) galaxies and 10(exp 8) stars. Since the size of this data set precludes manual analysis and classification of objects, our approach is to develop a software system which integrates independently developed techniques for image processing and data classification. Image processing routines are applied to identify and measure features of sky objects. Selected features are used to determine the classification of each object. GID3* and O-BTree, two inductive learning techniques, are used to automatically learn classification decision trees from examples. We describe the techniques used, the details of our specific application, and the initial encouraging results which indicate that our approach is well-suited to the problem. The benefits of the approach are increased data reduction throughput, consistency of classification, and the automated derivation of classification rules that will form an objective, examinable basis for classifying sky objects. Furthermore, astronomers will be freed from the tedium of an intensely visual task to pursue more challenging analysis and interpretation problems given automatically cataloged data.

Maximizing Iodine Contrast-to-Noise Ratios in Abdominal CT Imaging through Use of Energy Domain Noise Reduction and Virtual Monoenergetic Dual-Energy CT.

PubMed

Leng, Shuai; Yu, Lifeng; Fletcher, Joel G; McCollough, Cynthia H

2015-08-01

To determine the iodine contrast-to-noise ratio (CNR) for abdominal computed tomography (CT) when using energy domain noise reduction and virtual monoenergetic dual-energy (DE) CT images and to compare the CNR to that attained with single-energy CT at 80, 100, 120, and 140 kV. This HIPAA-compliant study was approved by the institutional review board with waiver of informed consent. A syringe filled with diluted iodine contrast material was placed into 30-, 35-, and 45-cm-wide water phantoms and scanned with a dual-source CT scanner in both DE and single-energy modes with matched scanner output. Virtual monoenergetic images were generated, with energies ranging from 40 to 110 keV in 10-keV steps. A previously developed energy domain noise reduction algorithm was applied to reduce image noise by exploiting information redundancies in the energy domain. Image noise and iodine CNR were calculated. To show the potential clinical benefit of this technique, it was retrospectively applied to a clinical DE CT study of the liver in a 59-year-old male patient by using conventional and iterative reconstruction techniques. Image noise and CNR were compared for virtual monoenergetic images with and without energy domain noise reduction at each virtual monoenergetic energy (in kiloelectron volts) and phantom size by using a paired t test. CNR of virtual monoenergetic images was also compared with that of single-energy images acquired with 80, 100, 120, and 140 kV. Noise reduction of up to 59% (28.7 of 65.7) was achieved for DE virtual monoenergetic images by using an energy domain noise reduction technique. For the commercial virtual monoenergetic images, the maximum iodine CNR was achieved at 70 keV and was 18.6, 16.6, and 10.8 for the 30-, 35-, and 45-cm phantoms. After energy domain noise reduction, maximum iodine CNR was achieved at 40 keV and increased to 30.6, 25.4, and 16.5. These CNRs represented improvement of up to 64% (12.0 of 18.6) with the energy domain noise reduction technique. For single-energy CT at the optimal tube potential, iodine CNR was 29.1 (80 kV), 21.2 (80 kV), and 11.5 (100 kV). For patient images, 39% (24 of 61) noise reduction and 67% (0.74 of 1.10) CNR improvement were observed with the energy domain noise reduction technique when compared with standard filtered back-projection images. Iodine CNR for adult abdominal CT may be maximized with energy domain noise reduction and virtual monoenergetic DE CT. (©) RSNA, 2015.

Grinding Si3N4 Powder In Si3N4 Equipment

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Freedman, Marc R.; Kiser, James D.

1989-01-01

Three methods of grinding compared. Report based on study of grinding silicon nitride powder in preparation for sintering into solid ceramic material. Attrition, vibratory, and ball mills lined with reaction-bonded silicon nitride tested. Rates of reduction of particle sizes and changes in chemical compositions of powders measured so grinding efficiences and increases in impurity contents from wear of mills and media evaluated for each technique.

Intrinsic magnetic properties of bimetallic nanoparticles elaborated by cluster beam deposition.

PubMed

Dupuis, V; Khadra, G; Hillion, A; Tamion, A; Tuaillon-Combes, J; Bardotti, L; Tournus, F

2015-11-14

In this paper, we present some specific chemical and magnetic order obtained very recently on characteristic bimetallic nanoalloys prepared by mass-selected Low Energy Cluster Beam Deposition (LECBD). We study how the competition between d-atom hybridization, complex structure, morphology and chemical affinity affects their intrinsic magnetic properties at the nanoscale. The structural and magnetic properties of these nanoalloys were investigated using various experimental techniques that include High Resolution Transmission Electron Microscopy (HRTEM), Superconducting Quantum Interference Device (SQUID) magnetometry, as well as synchrotron techniques such as Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Magnetic Circular Dichroism (XMCD). Depending on the chemical nature of the nanoalloys we observe different magnetic responses compared to their bulk counterparts. In particular, we show how specific relaxation in nanoalloys impacts their magnetic anisotropy; and how finite size effects (size reduction) inversely enhance their magnetic moment.

Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

NASA Astrophysics Data System (ADS)

Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

2016-10-01

X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

Trimming a hazard logic tree with a new model-order-reduction technique

USGS Publications Warehouse

Porter, Keith; Field, Edward; Milner, Kevin R

2017-01-01

The size of the logic tree within the Uniform California Earthquake Rupture Forecast Version 3, Time-Dependent (UCERF3-TD) model can challenge risk analyses of large portfolios. An insurer or catastrophe risk modeler concerned with losses to a California portfolio might have to evaluate a portfolio 57,600 times to estimate risk in light of the hazard possibility space. Which branches of the logic tree matter most, and which can one ignore? We employed two model-order-reduction techniques to simplify the model. We sought a subset of parameters that must vary, and the specific fixed values for the remaining parameters, to produce approximately the same loss distribution as the original model. The techniques are (1) a tornado-diagram approach we employed previously for UCERF2, and (2) an apparently novel probabilistic sensitivity approach that seems better suited to functions of nominal random variables. The new approach produces a reduced-order model with only 60 of the original 57,600 leaves. One can use the results to reduce computational effort in loss analyses by orders of magnitude.

Primary Class Size Reduction: How Policy Space, Physical Space, and Spatiality Shape What Happens in Real Schools

ERIC Educational Resources Information Center

Bascia, Nina; Faubert, Brenton

2012-01-01

This article reviews the literature base on class size reduction and proposes a new analytic framework that we believe provides practically useful explanations of how primary class size reduction works. It presents descriptions of classroom practice and grounded explanations for how class size reduction affects educational core activities by…

Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds

NASA Astrophysics Data System (ADS)

Sinha, Tanur; Ahmaruzzaman, M.; Sil, A. K.; Bhattacharjee, Archita

2014-10-01

In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a ‘reducing agent' and ‘stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.

Optimization of Process Parameters in Preparation of Nanoemulsions of CLnA Rich Oil by Response Surface Methodology

NASA Astrophysics Data System (ADS)

Sengupta, Avery; Gupta, Surashree Sen; Ghosh, Mahua

2013-03-01

The purpose of the present study was to obtain optimal processing for preparation of uniform-sized nanoemulsion of conjugated linolenic acid (CLnA) rich oil to increase the oxidative stability of CLnA by using a high-speed disperser (HSD) and ultrasonication. The emulsifiers used were egg phospholipid and soya protein isolate. The effects of oil concentration [0.05 to 1.25 % (w/w)], emulsifier ratio [0.1:0.9 to 0.9:0.1 (phospholipid:protein)], speed of the HSD (2,000 to 12,000 rpm) and times of HSD and sonication treatments (10 to 50 min) were observed. Optimization was performed with and without response surface methodology (RSM). The optimum compositional variables i.e. concentration of oil was 1 % and phospholipid:protein molar ratio was 0.5:0.5. Maximum size reduction occurred at 10,000 rpm speed of HSD. HSD should be administered for 40 min followed by 40 min ultrasonication. The range of the size of the droplets in the nanoemulsion was between 173 ± 1.20 and 183 ± 0.94 nm. Nanoemulsion is a size reduction technique where the oil present in the emulsion can be easily stabilized which increases the shelf-life of the oil. The present study derived the reaction parameters were optimized using RSM to produce nanoemulsion of CLnA rich oils of minimum size to obtain maximum stability.

Size reduction techniques for vital compliant VHDL simulation models

DOEpatents

Rich, Marvin J.; Misra, Ashutosh

2006-08-01

A method and system select delay values from a VHDL standard delay file that correspond to an instance of a logic gate in a logic model. Then the system collects all the delay values of the selected instance and builds super generics for the rise-time and the fall-time of the selected instance. Then, the system repeats this process for every delay value in the standard delay file (310) that correspond to every instance of every logic gate in the logic model. The system then outputs a reduced size standard delay file (314) containing the super generics for every instance of every logic gate in the logic model.

The impact of microfluidic mixing of triblock micelleplexes on in vitro / in vivo gene silencing and intracellular trafficking

NASA Astrophysics Data System (ADS)

Feldmann, Daniel P.; Xie, Yuran; Jones, Steven K.; Yu, Dongyue; Moszczynska, Anna; Merkel, Olivia M.

2017-06-01

The triblock copolymer polyethylenimine-polycaprolactone-polyethylene glycol (PEI-PCL-PEG) has been shown to spontaneously assemble into nano-sized particulate carriers capable of complexing with nucleic acids for gene delivery. The objective of this study was to investigate micelleplex characteristics, their in vitro and in vivo fate following microfluidic preparation of siRNA nanoparticles compared to the routinely used batch reactor mixing technique. Herein, PEI-PCL-PEG nanoparticles were prepared with batch reactor or microfluidic mixing techniques and characterized by various biochemical assays and in cell culture. Microfluidic nanoparticles showed a reduction of overall particle size as well as a more uniform size distribution when compared to batch reactor pipette mixing. Confocal microscopy, flow cytometry and qRT-PCR displayed the subcellular delivery of the microfluidic formulation and confirmed the ability to achieve mRNA knockdown. Intratracheal instillation of microfluidic formulation resulted in a significantly more efficient (p < 0.05) knockdown of GAPDH compared to treatment with the batch reactor formulation. The use of microfluidic mixing techniques yields an overall smaller and more uniform PEG-PCL-PEI nanoparticle that is able to more efficiently deliver siRNA in vivo. This preparation method may prove to be useful when a scaled up production of well-defined polyplexes is required.

Bottom-up strategies for the assembling of magnetic systems using nanoclusters

NASA Astrophysics Data System (ADS)

Dupuis, V.; Hillion, A.; Robert, A.; Loiselet, O.; Khadra, G.; Capiod, P.; Albin, C.; Boisron, O.; Le Roy, D.; Bardotti, L.; Tournus, F.; Tamion, A.

2018-05-01

In the frame of the 20th Anniversary of the Journal of Nanoparticle Research (JNR), our aim is to start from the historical context 20 years ago and to give some recent results and perspectives concerning nanomagnets prepared from clusters preformed in the gas phase using the low-energy cluster beam deposition (LECBD) technique. In this paper, we focus our attention on the typical case of Co clusters embedded in various matrices to study interface magnetic anisotropy and magnetic interactions as a function of volume concentrations, and on still current and perspectives through two examples of binary metallic 3d-5d TM (namely CoPt and FeAu) cluster assemblies to illustrate size-related and nanoalloy phenomena on magnetic properties in well-defined mass-selected clusters. The structural and magnetic properties of these cluster assemblies were investigated using various experimental techniques that include high-resolution transmission electron microscopy (HRTEM), superconducting quantum interference device (SQUID) magnetometry, and synchrotron techniques such as extended X-ray absorption fine structure (EXAFS) and X-ray magnetic circular dichroism (XMCD). Depending on the chemical nature of both NPs and matrix, we observe different magnetic responses compared to their bulk counterparts. In particular, we show how finite size effects (size reduction) enhance their magnetic moment and how specific relaxation in nanoalloys can impact their magnetic anisotropy.

Green synthesis of silver nanoparticles from aqueous Aegle marmelos leaf extract

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jagajjanani Rao, K.; Paria, Santanu, E-mail: santanuparia@yahoo.com

Graphical abstract: Silver nanoparticles capped with polyphenols present in Aegle marmelos leaf extract. Display Omitted Highlights: ► Silver nanoparticles are synthesized using Aegle marmelos leaf extract in aqueous media. ► Reduction reaction is fast and occurs at room temperature. ► The presence of polyphenols acts as in situ capping agent. -- Abstract: Synthesis of nanoparticles by green route is an emerging technique drawing more attention recently because of several advantages over the convention chemical routes. The present study reports one-pot synthesis and in situ stabilization of silver nanoparticles using Aegle marmelos leaf extract. Nanoparticles of almost uniform spherical size (∼60more » nm) were synthesized within ∼25 min reaction time at room temperature. The size of particles depends on the ratio of AgNO{sub 3} and leaf extract. The crystallinity, size, and shape of the nanoparticles were characterized by X-ray diffraction, dynamic light scattering, and scanning electron microscopy respectively. The size stability was attained by the capping effect of polyphenolic tannin compound, procatacheuate in the extract. The capped polyphenols can be removed from the particle surface by simple NaOH/methanol wash. The involvement of phenolic compounds in metal ion reduction and capping were supported by UV–visible spectroscopy, infrared spectroscopy, high performance liquid chromatography, and zeta potential measurements.« less

Wax encapsulation of water-soluble compounds for application in foods.

PubMed

Mellema, M; Van Benthum, W A J; Boer, B; Von Harras, J; Visser, A

2006-11-01

Water-soluble ingredients have been successfully encapsulated in wax using two preparation techniques. The first technique ('solid preparation') leads to relatively large wax particles. The second technique ('liquid preparation') leads to relatively small wax particles immersed in vegetable oil. On the first technique: stable encapsulation of water-soluble colourants (dissolved at low concentration in water) has been achieved making use of beeswax and PGPR. The leakage from the capsules, for instance of size 2 mm, is about 30% after 16 weeks storage in water at room temperature. To form such capsules a minimum wax mass of 40% relative to the total mass is needed. High amounts of salt or acids at the inside water phase causes more leaking, probably because of the osmotic pressure difference. Osmotic matching of inner and outer phase can lead to a dramatic reduction in leakage. Fat capsules are less suitable to incorporate water soluble colourants. The reason for this could be a difference in crystal structure (fat is less ductile and more brittle). On the second technique: stable encapsulation of water-soluble colourants (encapsulated in solid wax particles) has been achieved making use of carnauba wax. The leakage from the capsules, for instance of size 250 mm, is about 40% after 1 weeks storage in water at room temperature.

Integrating Dimension Reduction and Out-of-Sample Extension in Automated Classification of Ex Vivo Human Patellar Cartilage on Phase Contrast X-Ray Computed Tomography

PubMed Central

Nagarajan, Mahesh B.; Coan, Paola; Huber, Markus B.; Diemoz, Paul C.; Wismüller, Axel

2015-01-01

Phase contrast X-ray computed tomography (PCI-CT) has been demonstrated as a novel imaging technique that can visualize human cartilage with high spatial resolution and soft tissue contrast. Different textural approaches have been previously investigated for characterizing chondrocyte organization on PCI-CT to enable classification of healthy and osteoarthritic cartilage. However, the large size of feature sets extracted in such studies motivates an investigation into algorithmic feature reduction for computing efficient feature representations without compromising their discriminatory power. For this purpose, geometrical feature sets derived from the scaling index method (SIM) were extracted from 1392 volumes of interest (VOI) annotated on PCI-CT images of ex vivo human patellar cartilage specimens. The extracted feature sets were subject to linear and non-linear dimension reduction techniques as well as feature selection based on evaluation of mutual information criteria. The reduced feature set was subsequently used in a machine learning task with support vector regression to classify VOIs as healthy or osteoarthritic; classification performance was evaluated using the area under the receiver-operating characteristic (ROC) curve (AUC). Our results show that the classification performance achieved by 9-D SIM-derived geometric feature sets (AUC: 0.96 ± 0.02) can be maintained with 2-D representations computed from both dimension reduction and feature selection (AUC values as high as 0.97 ± 0.02). Thus, such feature reduction techniques can offer a high degree of compaction to large feature sets extracted from PCI-CT images while maintaining their ability to characterize the underlying chondrocyte patterns. PMID:25710875

Development of a Multiple-Stage Differential Mobility Analyzer (MDMA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Da-Ren; Cheng, Mengdawn

2007-01-01

A new DMA column has been designed with the capability of simultaneously extracting monodisperse particles of different sizes in multiple stages. We call this design a multistage DMA, or MDMA. A prototype MDMA has been constructed and experimentally evaluated in this study. The new column enables the fast measurement of particles in a wide size range, while preserving the powerful particle classification function of a DMA. The prototype MDMA has three sampling stages, capable of classifying monodisperse particles of three different sizes simultaneously. The scanning voltage operation of a DMA can be applied to this new column. Each stage ofmore » MDMA column covers a fraction of the entire particle size range to be measured. The covered size fractions of two adjacent stages of the MDMA are designed somewhat overlapped. The arrangement leads to the reduction of scanning voltage range and thus the cycling time of the measurement. The modular sampling stage design of the MDMA allows the flexible configuration of desired particle classification lengths and variable number of stages in the MDMA. The design of our MDMA also permits operation at high sheath flow, enabling high-resolution particle size measurement and/or reduction of the lower sizing limit. Using the tandem DMA technique, the performance of the MDMA, i.e., sizing accuracy, resolution, and transmission efficiency, was evaluated at different ratios of aerosol and sheath flowrates. Two aerosol sampling schemes were investigated. One was to extract aerosol flows at an evenly partitioned flowrate at each stage, and the other was to extract aerosol at a rate the same as the polydisperse aerosol flowrate at each stage. We detail the prototype design of the MDMA and the evaluation result on the transfer functions of the MDMA at different particle sizes and operational conditions.« less

Reduction of ventricular size after shunting for normal pressure hydrocephalus related to CSF dynamics before shunting.

PubMed Central

Tans, J T; Poortvliet, D C

1988-01-01

Reduction of ventricular size was determined by repeated computed tomography in 30 adult patients shunted for normal pressure hydrocephalus (NPH) and related to the pressure-volume index (PVI) and resistance to outflow of cerebrospinal fluid (Rcsf) measured before shunting. Rapid and marked reduction of ventricular size (n = 10) was associated with a significantly lower PVI than slow and moderate to marked (n = 13) or minimal to mild reduction (n = 7). Otherwise no relationship could be found between the reduction of ventricular size and PVI or Rcsf. It is concluded that both rate and magnitude of reduction of ventricular size after shunting for NPH are extremely variable. High brain elasticity seems to be the best predictor of rapid and marked reduction. PMID:3379425

Gold particle formation via photoenhanced deposition on lithium niobate

NASA Astrophysics Data System (ADS)

Zaniewski, A. M.; Meeks, V.; Nemanich, R. J.

2017-05-01

In this work, we report on a technique to reduce gold chloride into sub-micron particles and nanoparticles. We use photoelectron transfer from periodically polarized lithium niobate (PPLN) illuminated with above band gap light to drive the surface reactions required for the reduction and particle formation. The particle sizes and distributions on the PPLN surface are sensitive to the solution concentration, with inhibited nucleation and large particles (>150 nm) for both low (2E-8M to 9E-7M) and high (1E-5M to 1E-3M) concentrations of gold chloride. At midrange values of the concentration, nucleation is more frequent, resulting in smaller sized particles (<150 nm). We compare the deposition process to that for silver, which has been previously studied. We find that the reduction of gold chloride into nanoparticles is inhibited compared to silver ion reduction, due to the multi-step reaction required for gold particle formation. This also has consequences for the resulting deposition patterns: while silver deposits into nanowires along boundaries between areas with opposite signed polarizations, such patterning of the deposition is not observed for gold, for a wide range of concentrations studied (2E-8 to 1E-3M).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chenyu; Chen, Dennis P.; Unocic, Raymond R.

The high performance of Pd-based intermetallic nanocatalysts has the potential to replace Pt-containing catalysts for fuel-cell reactions. Conventionally, intermetallic particles are obtained through the annealing of nanoparticles of a random alloy distribution. However, this method inevitably leads to sintering of the nanoparticles and generates polydisperse samples. Here, monodisperse PdCu nanoparticles with the ordered B2 phase were synthesized by seed-mediated co-reduction using PdCu nanoparticle seeds with a random alloy distribution (A1 phase). A time-evolution study suggests that the particles must overcome a size-dependent activation barrier for the ordering process to occur. Characterization of the as-prepared PdCu B2 nanoparticles by electron microscopymore » techniques revealed surface segregation of Pd as a thin shell over the PdCu core. The ordered nanoparticles exhibit superior activity and durability for the oxygen reduction reaction in comparison with PdCu A1 nanoparticles. This seed-mediated co-reduction strategy produced monodisperse nanoparticles ideally suited for structure–activity studies. Furthermore, the study of their growth mechanism provides insights into the size dependence of disorder–order transformations of bimetallic alloys at the nanoscale, which should enable the design of synthetic strategies toward other intermetallic systems.« less

Solid oxide fuel cell cathode infiltrate particle size control and oxygen surface exchange resistance determination

NASA Astrophysics Data System (ADS)

Burye, Theodore E.

Over the past decade, nano-sized Mixed Ionic Electronic Conducting (MIEC) -- micro-sized Ionic Conducting (IC) composite cathodes produced by the infiltration method have received much attention in the literature due to their low polarization resistance (RP) at intermediate (500-700°C) operating temperatures. Small infiltrated MIEC oxide nano-particle size and low intrinsic MIEC oxygen surface exchange resistance (Rs) have been two critical factors allowing these Nano-Micro-Composite Cathodes (NMCCs) to achieve high performance and/or low temperature operation. Unfortunately, previous studies have not found a reliable method to control or reduce infiltrated nano-particle size. In addition, controversy exists on the best MIEC infiltrate composition because: 1) Rs measurements on infiltrated MIEC particles are presently unavailable in the literature, and 2) bulk and thin film Rs measurements on nominally identical MIEC compositions often vary by up to 3 orders of magnitude. Here, two processing techniques, precursor nitrate solution desiccation and ceria oxide pre-infiltration, were developed to systematically produce a reduction in the average La0.6Sr0.4Co0.8Fe 0.2O3-delta (LSCF) infiltrated nano-particle size from 50 nm to 22 nm. This particle size reduction reduced the SOFC operating temperature, (defined as the temperature where RP=0.1 Ocm 2) from 650°C to 540°C. In addition, Rs values for infiltrated MIEC particles were determined for the first time through finite element modeling calculations on 3D Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) reconstructions of electrochemically characterized infiltrated electrodes.

The effects of anesthetic agents on pupillary function during general anesthesia using the automated infrared quantitative pupillometer.

PubMed

Shirozu, Kazuhiro; Setoguchi, Hidekazu; Tokuda, Kentaro; Karashima, Yuji; Ikeda, Mizuko; Kubo, Makoto; Nakamura, Katsuya; Hoka, Sumio

2017-04-01

Pupil reactivity can be used to evaluate central nervous system function and can be measured using a quantitative pupillometer. However, whether anesthetic agents affect the accuracy of the technique remains unclear. We examined the effects of anesthetic agents on pupillary reactivity. Thirty-five patients scheduled for breast or thyroid surgery were enrolled in the study. Patients were divided into four groups based on the technique used to maintain anesthesia: a sevoflurane-remifentanil (SEV/REM) group, a sevoflurane (SEV) group, a desflurane-remifentanil (DES/REM) group, and a propofol-remifentanil (PRO/REM) group. We measured maximum resting pupil size (MAX), reduction pupil size ratio (%CH), latency duration (LAT) and neurological pupil index (NPi). A marked reduction in MAX and %CH compared with baseline was observed in all groups, but LAT was unchanged during surgery. NPi reduced within the first hour of surgery in the SEV/REM, SEV, and DES/REM groups, but was not significantly different in the PRO/REM group. Compared with the PRO/REM group, mean %CH and NPi in patients anesthetized with SEV/REM, SEV or DES/REM were markedly lower at 1 h after surgery had commenced. There was no correlation between NPi and bispectral index. Fentanyl given alone decreased pupil size and %CH in light reflex, but did not change the NPi. NPi was decreased by inhalational anesthesia not but intravenous anesthesia. The difference in pupil reactivity between inhalational anesthetic and propofol may indicate differences in the alteration of midbrain reflexs in patients under inhalational or intravenous anesthesia.

Visual pattern image sequence coding

NASA Technical Reports Server (NTRS)

Silsbee, Peter; Bovik, Alan C.; Chen, Dapang

1990-01-01

The visual pattern image coding (VPIC) configurable digital image-coding process is capable of coding with visual fidelity comparable to the best available techniques, at compressions which (at 30-40:1) exceed all other technologies. These capabilities are associated with unprecedented coding efficiencies; coding and decoding operations are entirely linear with respect to image size and entail a complexity that is 1-2 orders of magnitude faster than any previous high-compression technique. The visual pattern image sequence coding to which attention is presently given exploits all the advantages of the static VPIC in the reduction of information from an additional, temporal dimension, to achieve unprecedented image sequence coding performance.

Low-Cost Fabrication of Printed Electronics Devices through Continuous Wave Laser-Induced Forward Transfer.

PubMed

Sopeña, Pol; Arrese, Javier; González-Torres, Sergio; Fernández-Pradas, Juan Marcos; Cirera, Albert; Serra, Pere

2017-09-06

Laser-induced forward transfer (LIFT) is a direct-writing technique that allows printing inks from a liquid film in a similar way to inkjet printing but with fewer limitations concerning ink viscosity and loading particle size. In this work, we prove that liquid inks can be printed through LIFT by using continuous wave (CW) instead of pulsed lasers, which allows a substantial reduction in the cost of the printing system. Through the fabrication of a functional circuit on both rigid and flexible substrates (plastic and paper), we provide a proof-of-concept that demonstrates the versatility of the technique for printed electronics applications.

Image compression/decompression based on mathematical transform, reduction/expansion, and image sharpening

DOEpatents

Fu, Chi-Yung; Petrich, Loren I.

1997-01-01

An image represented in a first image array of pixels is first decimated in two dimensions before being compressed by a predefined compression algorithm such as JPEG. Another possible predefined compression algorithm can involve a wavelet technique. The compressed, reduced image is then transmitted over the limited bandwidth transmission medium, and the transmitted image is decompressed using an algorithm which is an inverse of the predefined compression algorithm (such as reverse JPEG). The decompressed, reduced image is then interpolated back to its original array size. Edges (contours) in the image are then sharpened to enhance the perceptual quality of the reconstructed image. Specific sharpening techniques are described.

Synthesis of silver nanoparticles: chemical, physical and biological methods

PubMed Central

Iravani, S.; Korbekandi, H.; Mirmohammadi, S.V.; Zolfaghari, B.

2014-01-01

Silver nanoparticles (NPs) have been the subjects of researchers because of their unique properties (e.g., size and shape depending optical, antimicrobial, and electrical properties). A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. This review presents an overview of silver nanoparticle preparation by physical, chemical, and biological synthesis. The aim of this review article is, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of the above mentioned techniques for industries. PMID:26339255

Blood flow measurement in extracorporeal circulation using self-mixing laser diode

NASA Astrophysics Data System (ADS)

Cattini, Stefano; Norgia, Michele; Pesatori, Alessandro; Rovati, Luigi

2010-02-01

To measure blood flow rate in ex-vivo circulation, we propose an optical Doppler flowmeter based on the self-mixing effect within a laser diode (SM-LD). Advantages in adopting SM-LD techniques derive from reduced costs, ease of implementation and limited size. Moreover, the provided contactless sensing allows sensor reuse, hence further cost reduction. Preliminary measurements performed on bovine blood are reported, thus demonstrating the applicability of the proposed measurement method.

Biomimicry of multifunctional nanostructures in the neck feathers of mallard (Anas platyrhynchos L.) drakes

NASA Astrophysics Data System (ADS)

Khudiyev, Tural; Dogan, Tamer; Bayindir, Mehmet

2014-04-01

Biological systems serve as fundamental sources of inspiration for the development of artificially colored devices, and their investigation provides a great number of photonic design opportunities. While several successful biomimetic designs have been detailed in the literature, conventional fabrication techniques nonetheless remain inferior to their natural counterparts in complexity, ease of production and material economy. Here, we investigate the iridescent neck feathers of Anas platyrhynchos drakes, show that they feature an unusual arrangement of two-dimensional (2D) photonic crystals and further exhibit a superhydrophobic surface, and mimic this multifunctional structure using a nanostructure composite fabricated by a recently developed top-down iterative size reduction method, which avoids the above-mentioned fabrication challenges, provides macroscale control and enhances hydrophobicity through the surface structure. Our 2D solid core photonic crystal fibres strongly resemble drake neck plumage in structure and fully polymeric material composition, and can be produced in wide array of colors by minor alterations during the size reduction process.

Biomimicry of multifunctional nanostructures in the neck feathers of mallard (Anas platyrhynchos L.) drakes

PubMed Central

Khudiyev, Tural; Dogan, Tamer; Bayindir, Mehmet

2014-01-01

Biological systems serve as fundamental sources of inspiration for the development of artificially colored devices, and their investigation provides a great number of photonic design opportunities. While several successful biomimetic designs have been detailed in the literature, conventional fabrication techniques nonetheless remain inferior to their natural counterparts in complexity, ease of production and material economy. Here, we investigate the iridescent neck feathers of Anas platyrhynchos drakes, show that they feature an unusual arrangement of two-dimensional (2D) photonic crystals and further exhibit a superhydrophobic surface, and mimic this multifunctional structure using a nanostructure composite fabricated by a recently developed top-down iterative size reduction method, which avoids the above-mentioned fabrication challenges, provides macroscale control and enhances hydrophobicity through the surface structure. Our 2D solid core photonic crystal fibres strongly resemble drake neck plumage in structure and fully polymeric material composition, and can be produced in wide array of colors by minor alterations during the size reduction process. PMID:24751587

Biomimicry of multifunctional nanostructures in the neck feathers of mallard (Anas platyrhynchos L.) drakes.

PubMed

Khudiyev, Tural; Dogan, Tamer; Bayindir, Mehmet

2014-04-22

Biological systems serve as fundamental sources of inspiration for the development of artificially colored devices, and their investigation provides a great number of photonic design opportunities. While several successful biomimetic designs have been detailed in the literature, conventional fabrication techniques nonetheless remain inferior to their natural counterparts in complexity, ease of production and material economy. Here, we investigate the iridescent neck feathers of Anas platyrhynchos drakes, show that they feature an unusual arrangement of two-dimensional (2D) photonic crystals and further exhibit a superhydrophobic surface, and mimic this multifunctional structure using a nanostructure composite fabricated by a recently developed top-down iterative size reduction method, which avoids the above-mentioned fabrication challenges, provides macroscale control and enhances hydrophobicity through the surface structure. Our 2D solid core photonic crystal fibres strongly resemble drake neck plumage in structure and fully polymeric material composition, and can be produced in wide array of colors by minor alterations during the size reduction process.

Multi-Mode Excitation and Data Reduction for Fatigue Crack Characterization in Conducting Plates

NASA Technical Reports Server (NTRS)

Wincheski, B.; Namkung, M.; Fulton, J. P.; Clendenin, C. G.

1992-01-01

Advances in the technique of fatigue crack characterization by resonant modal analysis have been achieved through a new excitation mechanism and data reduction of multiple resonance modes. A non-contacting electromagnetic device is used to apply a time varying Lorentz force to thin conducting sheets. The frequency and direction of the Lorentz force are such that resonance modes are generated in the test sample. By comparing the change in frequency between distinct resonant modes of a sample, detecting and sizing of fatigue cracks are achieved and frequency shifts caused by boundary condition changes can be discriminated against. Finite element modeling has been performed to verify experimental results.

Retinal blood flow during hyperoxia in humans revisited: concerted results using different measurement techniques.

PubMed

Kiss, Barbara; Polska, Elzbieta; Dorner, Guido; Polak, Kaija; Findl, Oliver; Mayrl, Gabriele Fuchsjäger; Eichler, Hans-Georg; Wolzt, Michael; Schmetterer, Leopold

2002-07-01

Retinal vasculature shows pronounced vasoconstriction in response to hyperoxia, which appears to be related to the constant oxygen demand of the retina. However, the exact amount of blood flow reduction and the exact time course of this phenomenon are still a matter of debate. We set out to investigate the retinal response to hyperoxia using innovative techniques for the assessment of retinal hemodynamics. In a total of 48 healthy volunteers we studied the effect of 100% O(2) breathing on retinal blood flow using two methods. Red blood cell movement in larger retinal veins was quantified with combined laser Doppler velocimetry and retinal vessel size measurement. Retinal white blood cell movement was quantified with the blue field entoptic technique. The time course of retinal vasoconstriction in response to hyperoxia was assessed by continuous vessel size determination using the Zeiss retinal vessel analyzer. The response to hyperoxia as measured with combined laser Doppler velocimetry and vessel size measurement was almost twice as high as that observed with the blue field technique. Vasoconstriction in response to 100% O(2) breathing occurred within the first 5 min and no counterregulatory or adaptive mechanisms were observed. Based on these results we hypothesize that hyperoxia-induced vasoconstriction differentially affects red and white blood cell movement in the human retina. This hypothesis is based on the complex interactions between red and white blood cells in microcirculation, which have been described in detail for other vascular beds.

Allanite age-dating: Non-matrix-matched standardization in quadrupole LA-ICP-MS

NASA Astrophysics Data System (ADS)

Burn, M.; Lanari, P.; Pettke, T.; Engi, M.

2014-12-01

Allanite Th-U-Pb age-dating has recently been found to be powerful in unraveling the timing of geological processes such as the metamorphic dynamics in subduction zones and crystallization velocity of magmas. However, inconsistencies among analytical techniques have raised doubts about the accuracy of allanite age data. Spot analysis techniques such as LA-ICP-MS are claimed to be crucially dependent on matrix-matched standards, the quality of which is variable. We present a new approach in LA-ICP-MS data reduction that allows non-matrix-matched standardization via well constrained zircon reference materials as primary standards. Our data were obtained using a GeoLas Pro 193 nm ArF excimer laser ablation system coupled to an ELAN DRC-e quadrupole ICP-MS. We use 32 μm and 24 μm spot sizes; laser operating conditions of 9 Hz repetition rate and 2.5 J/cm2 fluence have proven advantageous. Matrix dependent downhole fractionation evolution is empirically determined by analyzing 208Pb/232Th and 206Pb/238U and applied prior to standardization. The new data reduction technique was tested on three magmatic allanite reference materials (SISSb, CAPb, TARA); within error these show the same downhole fractionation evolution for all allanite types and in different analytical sessions, provided measurement conditions remain the same. Although the downhole evolution of allanite and zircon differs significantly, a link between zircon and allanite matrix is established by assuming CAPb and TARA to be fixed at the corresponding reference ages. Our weighted mean 208Pb/232Th ages are 30.06 ± 0.22 (2σ) for SISSb, 275.4 ± 1.3 (2σ) for CAPb, and 409.9 ± 1.8 (2σ) for TARA. Precision of single spot age data varies between 1.5 and 8 % (2σ), dependent on spot size and common lead concentrations. Quadrupole LA-ICP-MS allanite age-dating has thus similar uncertainties as do other spot analysis techniques. The new data reduction technique is much less dependent on quality and homogeneity of allanite standard reference materials. This method of correcting for matrix-dependent downhole fractionation evolution opens new possibilities in the field of LA-ICP-MS data acquisition, e.g. the use of a NIST standard glass to date all material types given a set of well constrained reference materials.

Histological and Ultrastructural Effects of Ultrasound-induced Cavitation on Human Skin Adipose Tissue.

PubMed

Bani, Daniele; Quattrini Li, Alessandro; Freschi, Giancarlo; Russo, Giulia Lo

2013-09-01

In aesthetic medicine, the most promising techniques for noninvasive body sculpturing purposes are based on ultrasound-induced fat cavitation. Liporeductive ultrasound devices afford clinically relevant subcutaneous fat pad reduction without significant adverse reactions. This study aims at evaluating the histological and ultrastructural changes induced by ultrasound cavitation on the different cell components of human skin. Control and ultrasound-treated ex vivo abdominal full-thickness skin samples and skin biopsies from patients pretreated with or without ultrasound cavitation were studied histologically, morphometrically, and ultrastructurally to evaluate possible changes in adipocyte size and morphology. Adipocyte apoptosis and triglyceride release were also assayed. Clinical evaluation of the effects of 4 weekly ultrasound vs sham treatments was performed by plicometry. Compared with the sham-treated control samples, ultrasound cavitation induced a statistically significant reduction in the size of the adipocytes (P < 0.001), the appearance of micropores and triglyceride leakage and release in the conditioned medium (P < 0.05 at 15 min), or adipose tissue interstitium, without appreciable changes in microvascular, stromal, and epidermal components and in the number of apoptotic adipocytes. Clinically, the ultrasound treatment caused a significant reduction of abdominal fat. This study further strengthens the current notion that noninvasive transcutaneous ultrasound cavitation is a promising and safe technology for localized reduction of fat and provides experimental evidence for its specific mechanism of action on the adipocytes.

Visualization of Subsurface Defects in Composites using a Focal Plane Array Infrared Camera

NASA Technical Reports Server (NTRS)

Plotnikov, Yuri A.; Winfree, William P.

1999-01-01

A technique for enhanced defect visualization in composites via transient thermography is presented in this paper. The effort targets automated defect map construction for multiple defects located in the observed area. Experimental data were collected on composite panels of different thickness with square inclusions and flat bottom holes of different depth and orientation. The time evolution of the thermal response and spatial thermal profiles are analyzed. The pattern generated by carbon fibers and the vignetting effect of the focal plane array camera make defect visualization difficult. An improvement of the defect visibility is made by the pulse phase technique and the spatial background treatment. The relationship between a size of a defect and its reconstructed image is analyzed as well. The image processing technique for noise reduction is discussed.

Speckle noise reduction of 1-look SAR imagery

NASA Technical Reports Server (NTRS)

Nathan, Krishna S.; Curlander, John C.

1987-01-01

Speckle noise is inherent to synthetic aperture radar (SAR) imagery. Since the degradation of the image due to this noise results in uncertainties in the interpretation of the scene and in a loss of apparent resolution, it is desirable to filter the image to reduce this noise. In this paper, an adaptive algorithm based on the calculation of the local statistics around a pixel is applied to 1-look SAR imagery. The filter adapts to the nonstationarity of the image statistics since the size of the blocks is very small compared to that of the image. The performance of the filter is measured in terms of the equivalent number of looks (ENL) of the filtered image and the resulting resolution degradation. The results are compared to those obtained from different techniques applied to similar data. The local adaptive filter (LAF) significantly increases the ENL of the final image. The associated loss of resolution is also lower than that for other commonly used speckle reduction techniques.

Mathematics and mallard management

USGS Publications Warehouse

Cowardin, L.M.; Johnson, D.H.

1979-01-01

Waterfowl managers can effectively use simple population models to aid in making management decisions. We present a basic model of the change in population size as related to survival and recruitment. A management technique designed to increase survival of mallards (Anas platyrhynchos) by limiting harvest on the Chippewa National Forest, Minnesota, is used to illustrate the application of models in decision making. The analysis suggests that the management technique would be of limited effectiveness. In a 2nd example, the change in mallard population in central North Dakota is related to implementing programs to create dense nesting cover with or without supplementary predator control. The analysis suggests that large tracts of land would be required to achieve a hypothetical management objective of increasing harvest by 50% while maintaining a stable population. Less land would be required if predator reduction were used in combination with cover management, but questions about effectiveness and ecological implications of large scale predator reduction remain unresolved. The use of models as a guide to planning research responsive to the needs of management is illustrated.

Phenanthrene binding by humic acid-protein complexes as studied by passive dosing technique.

PubMed

Zhao, Jian; Wang, Zhenyu; Ghosh, Saikat; Xing, Baoshan

2014-01-01

This work investigated the binding behavior of phenanthrene by humic acids (HA-2 and HA-5), proteins (bovine serum albumin (BSA)), lysozyme and pepsin), and their complexes using a passive dosing technique. All sorption isotherms were fitted well with Freundlich model and the binding capability followed an order of HA-5 > HA-2 > BSA > pepsin > lysozyme. In NaCl solution, phenanthrene binding to HA-BSA complexes was much higher than the sum of binding to individual HA and BSA, while there was no enhancement for HA-pepsin. Positively charged lysozyme slightly lowered phenanthrene binding on both HAs due to strong aggregation of HA-lysozyme complexes, leading to reduction in the number of binding sites. The binding enhancement by HA-BSA was observed under all tested ion species and ionic strengths. This enhancement can be explained by unfolding of protein, reduction of aggregate size and formation of HA-BSA complexes with favorable conformations for binding phenanthrene. Copyright © 2013 Elsevier Ltd. All rights reserved.

Particle morphology characterization and manipulation in biomass slurries and the effect on rheological properties and enzymatic conversion.

PubMed

Dibble, Clare J; Shatova, Tatyana A; Jorgenson, Jennie L; Stickel, Jonathan J

2011-01-01

An improved understanding of how particle size distribution relates to enzymatic hydrolysis performance and rheological properties could enable enhanced biochemical conversion of lignocellulosic feedstocks. Particle size distribution can change as a result of either physical or chemical manipulation of a biomass sample. In this study, we employed image processing techniques to measure slurry particle size distribution and validated the results by showing that they are comparable to those from laser diffraction and sieving. Particle size and chemical changes of biomass slurries were manipulated independently and the resulting yield stress and enzymatic digestibility of slurries with different size distributions were measured. Interestingly, reducing particle size by mechanical means from about 1 mm to 100 μm did not reduce the yield stress of the slurries over a broad range of concentrations or increase the digestibility of the biomass over the range of size reduction studied here. This is in stark contrast to the increase in digestibility and decrease in yield stress when particle size is reduced by dilute-acid pretreatment over similar size ranges. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

Size Reduction of Hamiltonian Matrix for Large-Scale Energy Band Calculations Using Plane Wave Bases

NASA Astrophysics Data System (ADS)

Morifuji, Masato

2018-01-01

We present a method of reducing the size of a Hamiltonian matrix used in calculations of electronic states. In the electronic states calculations using plane wave basis functions, a large number of plane waves are often required to obtain precise results. Even using state-of-the-art techniques, the Hamiltonian matrix often becomes very large. The large computational time and memory necessary for diagonalization limit the widespread use of band calculations. We show a procedure of deriving a reduced Hamiltonian constructed using a small number of low-energy bases by renormalizing high-energy bases. We demonstrate numerically that the significant speedup of eigenstates evaluation is achieved without losing accuracy.

A case of pediatric live-donor liver transplantation with a left lateral segment reduction by a linear stapler after reperfusion.

PubMed

Zenitani, Masahiro; Ueno, Takehisa; Nara, Keigo; Nakahata, Kengo; Uehara, Shuichiro; Soh, Hideki; Oue, Takaharu; Kondo, Hiroki; Nagano, Hiroaki; Usui, Noriaki

2014-09-01

In pediatric LDLT, graft reduction is sometimes required because of the graft size mismatch. Dividing the portal triad and hepatic veins with a linear stapler is a rapid and safe method of reduction. We herein present a case with a left lateral segment reduction achieved using a linear stapler after reperfusion in pediatric LDLT. The patient was a male who had previously undergone Kasai procedure for biliary atresia. We performed the LDLT with his father's lateral segment. According to the pre-operative volumetry, the GV/SLV ratio was 102.5%. As the patient's PV was narrow, sclerotic and thick, we decided to put an interposition with the IMV graft of the donor between the confluence and the graft PV. The graft PV was anastomosed to the IMV graft. The warm ischemic time was 34 min, and the cold ischemic time was 82 min. The ratio of the graft size to the recipient weight (G/R ratio) was 4.2%. After reperfusion, we found that the graft had poor perfusion and decided to reduce the graft size. We noted good perfusion in the residual area after the lateral edge was clamped with an intestinal clamp. The liver tissue was sufficiently fractured with an intestinal clamp and then was divided with a linear stapler. The final G/R ratio was 3.6%. The total length of the operation was 12 h and 20 min. The amount of blood lost was 430 mL. No surgical complications, including post-operative hemorrhage and bile leakage, were encountered. We believe that using the linear stapler decreased the duration of the operation and was an acceptable technique for reducing the graft after reperfusion. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Enhanced Tools and Techniques to Support Debris Management in Disaster Response Missions (Flood and Coastal Storm Damage Reduction Research and Development Program)

DTIC Science & Technology

2009-05-01

debris removal without restoration is deployed.  Conduct a controlled field study of restoration activity, for example, along the Wabash ...hazardous metals including chromium, cadmium , lead and mercury (MDEQ 2008; Thibodeau 2002). 3. Batteries in electronics and computers may contain lead...mercury, nickel and cadmium . Appliances Appliances are a problem mainly due to their large size, creating issues with loading, hauling, and

Macromolecular structure of coals. 6. Mass spectroscopic analysis of coal-derived liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooker, D.T.; Lucht, L.M.; Peppas, N.A.

1986-02-01

The macromolecular structure of coal networks was analyzed by depolymerizing coal samples using the Sternberg reductive alkylation and the Miyake alkylation techniques. Electron impact mass spectra showed peaks of greater abundance of 125-132, 252-260, 383-391, and 511-520 m/z ratios. Based on analysis of the patterns of the spectra, the cluster size of the cross-linked structure of bituminous coals was determined as 126-130. Various chemical species were identified.

Nanosizing of drugs: Effect on dissolution rate

PubMed Central

Dizaj, S. Maleki; Vazifehasl, Zh.; Salatin, S.; Adibkia, Kh.; Javadzadeh, Y.

2015-01-01

The solubility, bioavailability and dissolution rate of drugs are important parameters for achieving in vivo efficiency. The bioavailability of orally administered drugs depends on their ability to be absorbed via gastrointestinal tract. For drugs belonging to Class II of pharmaceutical classification, the absorption process is limited by drug dissolution rate in gastrointestinal media. Therefore, enhancement of the dissolution rate of these drugs will present improved bioavailability. So far several techniques such as physical and chemical modifications, changing in crystal habits, solid dispersion, complexation, solubilization and liquisolid method have been used to enhance the dissolution rate of poorly water soluble drugs. It seems that improvement of the solubility properties ofpoorly water soluble drugscan translate to an increase in their bioavailability. Nowadays nanotechnology offers various approaches in the area of dissolution enhancement of low aqueous soluble drugs. Nanosizing of drugs in the form of nanoparticles, nanocrystals or nanosuspensions not requiring expensive facilities and equipment or complicated processes may be applied as simple methods to increase the dissolution rate of poorly water soluble drugs. In this article, we attempted to review the effects of nanosizing on improving the dissolution rate of poorly aqueous soluble drugs. According to the reviewed literature, by reduction of drug particle size into nanometer size the total effective surface area is increased and thereby dissolution rate would be enhanced. Additionally, reduction of particle size leads to reduction of the diffusion layer thickness surrounding the drug particles resulting in the increment of the concentration gradient. Each of these process leads to improved bioavailability. PMID:26487886

Oil core microcapsules by inverse gelation technique.

PubMed

Martins, Evandro; Renard, Denis; Davy, Joëlle; Marquis, Mélanie; Poncelet, Denis

2015-01-01

A promising technique for oil encapsulation in Ca-alginate capsules by inverse gelation was proposed by Abang et al. This method consists of emulsifying calcium chloride solution in oil and then adding it dropwise in an alginate solution to produce Ca-alginate capsules. Spherical capsules with diameters around 3 mm were produced by this technique, however the production of smaller capsules was not demonstrated. The objective of this study is to propose a new method of oil encapsulation in a Ca-alginate membrane by inverse gelation. The optimisation of the method leads to microcapsules with diameters around 500 μm. In a search of microcapsules with improved diffusion characteristics, the size reduction is an essential factor to broaden the applications in food, cosmetics and pharmaceuticals areas. This work contributes to a better understanding of the inverse gelation technique and allows the production of microcapsules with a well-defined shell-core structure.

Numerical study of anomalous dynamic scaling behaviour of (1+1)-dimensional Das Sarma-Tamborenea model

NASA Astrophysics Data System (ADS)

Xun, Zhi-Peng; Tang, Gang; Han, Kui; Hao, Da-Peng; Xia, Hui; Zhou, Wei; Yang, Xi-Quan; Wen, Rong-Ji; Chen, Yu-Ling

2010-07-01

In order to discuss the finite-size effect and the anomalous dynamic scaling behaviour of Das Sarma-Tamborenea growth model, the (1+1)-dimensional Das Sarma-Tamborenea model is simulated on a large length scale by using the kinetic Monte-Carlo method. In the simulation, noise reduction technique is used in order to eliminate the crossover effect. Our results show that due to the existence of the finite-size effect, the effective global roughness exponent of the (1+1)-dimensional Das Sarma-Tamborenea model systematically decreases with system size L increasing when L > 256. This finding proves the conjecture by Aarao Reis[Aarao Reis F D A 2004 Phys. Rev. E 70 031607]. In addition, our simulation results also show that the Das Sarma-Tamborenea model in 1+1 dimensions indeed exhibits intrinsic anomalous scaling behaviour.

Role of microextraction sampling procedures in forensic toxicology.

PubMed

Barroso, Mário; Moreno, Ivo; da Fonseca, Beatriz; Queiroz, João António; Gallardo, Eugenia

2012-07-01

The last two decades have provided analysts with more sensitive technology, enabling scientists from all analytical fields to see what they were not able to see just a few years ago. This increased sensitivity has allowed drug detection at very low concentrations and testing in unconventional samples (e.g., hair, oral fluid and sweat), where despite having low analyte concentrations has also led to a reduction in sample size. Along with this reduction, and as a result of the use of excessive amounts of potentially toxic organic solvents (with the subsequent environmental pollution and costs associated with their proper disposal), there has been a growing tendency to use miniaturized sampling techniques. Those sampling procedures allow reducing organic solvent consumption to a minimum and at the same time provide a rapid, simple and cost-effective approach. In addition, it is possible to get at least some degree of automation when using these techniques, which will enhance sample throughput. Those miniaturized sample preparation techniques may be roughly categorized in solid-phase and liquid-phase microextraction, depending on the nature of the analyte. This paper reviews recently published literature on the use of microextraction sampling procedures, with a special focus on the field of forensic toxicology.

Synthesis and characterization of silver-nanoparticle-impregnated fiberglass and utility in water disinfection.

PubMed

Nangmenyi, Gordon; Yue, Zhongren; Mehrabi, Sharifeh; Mintz, Eric; Economy, James

2009-12-09

A number of researchers have deployed silver (Ag) nanoparticles through a number of techniques on various substrates including carbon, zeolites and polymers for water disinfection applications. However, Ag impregnated on an inorganic fiberglass surface through a simple electroless process was only recently reported for the first time. Fiberglass impregnated with Ag nanoparticles displays superior performance over carbon-based silver support systems but little is known about the factors that affect the architecture of the system, its interfacial properties and its consequent bactericidal activity. In this study, Ag content and particle size on a fiberglass substrate were manipulated by adjusting the AgNO(3) concentration, immersion time, temperature, solution pH and reduction temperature. The reduction chemistry of the Ag-nanoparticle-impregnated fiberglass is described and supported with thermal gravimetric analysis (TGA) and photoelectron spectroscopy (XPS) measurements. The Ag content along with the particle size and particle size distribution were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD). The Ag content on the fiberglass mats ranged from 0.04 to 4.7 wt% Ag/g-fiber with a size distribution of 10-900 nm under standard processing conditions. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the Ag desorption from the fiberglass substrate, while the bactericidal properties were evaluated against Escherichia coli (E. coli).

Synthesis and characterization of silver-nanoparticle-impregnated fiberglass and utility in water disinfection

NASA Astrophysics Data System (ADS)

Nangmenyi, Gordon; Yue, Zhongren; Mehrabi, Sharifeh; Mintz, Eric; Economy, James

2009-12-01

A number of researchers have deployed silver (Ag) nanoparticles through a number of techniques on various substrates including carbon, zeolites and polymers for water disinfection applications. However, Ag impregnated on an inorganic fiberglass surface through a simple electroless process was only recently reported for the first time. Fiberglass impregnated with Ag nanoparticles displays superior performance over carbon-based silver support systems but little is known about the factors that affect the architecture of the system, its interfacial properties and its consequent bactericidal activity. In this study, Ag content and particle size on a fiberglass substrate were manipulated by adjusting the AgNO3 concentration, immersion time, temperature, solution pH and reduction temperature. The reduction chemistry of the Ag-nanoparticle-impregnated fiberglass is described and supported with thermal gravimetric analysis (TGA) and photoelectron spectroscopy (XPS) measurements. The Ag content along with the particle size and particle size distribution were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD). The Ag content on the fiberglass mats ranged from 0.04 to 4.7 wt% Ag/g-fiber with a size distribution of 10-900 nm under standard processing conditions. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the Ag desorption from the fiberglass substrate, while the bactericidal properties were evaluated against Escherichia coli (E. coli).

Biomimetic synthesis of selenium nanoparticles by Pseudomonas aeruginosa ATCC 27853: An approach for conversion of selenite.

PubMed

Kora, Aruna Jyothi; Rastogi, Lori

2016-10-01

A facile and green method for the reduction of selenite was developed using a Gram-negative bacterial strain Pseudomonas aeruginosa, under aerobic conditions. During the process of bacterial conversion, the elemental selenium nanoparticles were produced. These nanoparticles were systematically characterized using various analytical techniques including UV-visible spectroscopy, XRD, Raman spectroscopy, SEM, DLS, TEM and FTIR spectroscopy techniques. The generation of selenium nanoparticles was confirmed from the appearance of red colour in the culture broth and broad absorption peaks in the UV-vis. The synthesized nanoparticles were spherical, polydisperse, ranged from 47 to 165 nm and the average particle size was about 95.9 nm. The selected-area electron diffraction, XRD patterns; and Raman spectroscopy established the amorphous nature of the fabricated nanoparticles. The IR data demonstrated the bacterial protein mediated selenite reduction and capping of the produced nanoparticles. The selenium removal was assessed at different selenite concentrations using ICP-OES and the results showed that the tested bacterial strain exhibited significant selenite reduction activity. The results demonstrate the possible application of P. aeruginosa for bioremediation of waters polluted with toxic and soluble selenite. Moreover, the potential metal reduction capability of the bacterial strain can function as green method for aerobic generation of selenium nanospheres. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chitosan based polymer matrix with silver nanoparticles decorated multiwalled carbon nanotubes for catalytic reduction of 4-nitrophenol.

PubMed

Alshehri, Saad M; Almuqati, Turki; Almuqati, Naif; Al-Farraj, Eida; Alhokbany, Norah; Ahamad, Tansir

2016-10-20

A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of microrolling parameters on the microstructure and deformation behavior of pure copper

NASA Astrophysics Data System (ADS)

Jing, Yi; Zhang, Hong-mei; Wu, Hao; Li, Lian-jie; Jia, Hong-bin; Jiang, Zheng-yi

2018-01-01

Microrolling experiments and uniaxial tensile tests of pure copper under different annealing conditions were carried out in this paper. The effects of grain size and reduction on non-uniform deformation, edge cracking, and microstructure were studied. The experimental results showed that the side deformation became more non-uniform, resulting in substantial edge bulge, and the uneven spread increased with increasing grain size and reduction level. When the reduction level reached 80% and the grain size was 65 μm, slight edge cracks occurred. When the grain size was 200 μm, the edge cracks became wider and deeper. No edge cracks occurred when the grain size was 200 μm and the reduction level was less than 60%; edge cracks occurred when the reduction level was increased to 80%. As the reduction level increased, the grains were gradually elongated and appeared as a sheet-like structure along the rolling direction; a fine lamellar structure was obtained when the grain size was 20 μm and the reduction level was less than 60%.

Comparison of image quality and radiation dose between fixed tube current and combined automatic tube current modulation in craniocervical CT angiography.

PubMed

Lee, E J; Lee, S K; Agid, R; Howard, P; Bae, J M; terBrugge, K

2009-10-01

The combined automatic tube current modulation (ATCM) technique adapts and modulates the x-ray tube current in the x-y-z axis according to the patient's individual anatomy. We compared image quality and radiation dose of the combined ATCM technique with those of a fixed tube current (FTC) technique in craniocervical CT angiography performed with a 64-section multidetector row CT (MDCT) system. A retrospective review of craniocervical CT angiograms (CTAs) by using combined ATCM (n = 25) and FTC techniques (n = 25) was performed. Other CTA parameters, such as kilovolt (peak), matrix size, FOV, section thickness, pitch, contrast agent, and contrast injection techniques, were held constant. We recorded objective image noise in the muscles at 2 anatomic levels: radiation exposure doses (CT dose index volume and dose-length product); and subjective image quality parameters, such as vascular delineation of various arterial vessels, visibility of small arterial detail, image artifacts, and certainty of diagnosis. The Mann-Whitney U test was used for statistical analysis. No significant difference was detected in subjective image quality parameters between the FTC and combined ATCM techniques. Most subjects in both study groups (49/50, 98%) had acceptable subjective artifacts. The objective image noise values at shoulder level did not show a significant difference, but the noise value at the upper neck was higher with the combined ATCM (P < .05) technique. Significant reduction in radiation dose (18% reduction) was noted with the combined ATCM technique (P < .05). The combined ATCM technique for craniocervical CTA performed at 64-section MDCT substantially reduced radiation exposure dose but maintained diagnostic image quality.

Formation of plasmonic silver nanoparticles using rapid thermal annealing at low temperature and study in reflectance reduction of Si surface

NASA Astrophysics Data System (ADS)

Barman, Bidyut; Dhasmana, Hrishikesh; Verma, Abhishek; Kumar, Amit; Pratap Chaudhary, Shiv; Jain, V. K.

2017-09-01

This work presents studies of plasmonic silver nanoparticles (AgNPs) formation at low temperatures (200 °C-300 °C) onto Si surface by sputtering followed with rapid thermal processing (RTP) for different time durations(5-30 min). The study reveals that 20 min RTP at all temperatures show minimum average size of AgNPs (60.42 nm) with corresponding reduction in reflectance of Si surface from 40.12% to mere 1.15% only in wavelength region 300-800 nm for RTP at 200 °C. A detailed supporting growth mechanism is also discussed. This low temperature technique can be helpful in achieving efficiency improvement in solar cells via reflectance reduction with additional features such as reproducibility, minimal time and very good adhesion without damaging underlying layers device parameters.

Effects of Reduction Osteotomy on Gap Balancing During Total Knee Arthroplasty for Severe Varus Deformity.

PubMed

Niki, Yasuo; Harato, Kengo; Nagai, Katsuya; Suda, Yasunori; Nakamura, Masaya; Matsumoto, Morio

2015-12-01

This study aimed to assess the effects of down-sizing and lateralizing of the tibial component (reduction osteotomy) on gap balancing in TKA, and the clinical feasibility of an uncemented modular trabecular metal tibial tray in this technique. Reduction osteotomy was performed for 39 knees of 36 patients with knee OA with a mean tibiofemoral angle of 21° varus. In 20 knees, appropriate gap balance was achieved by release of the deep medial collateral ligament alone. Flexion gap imbalance could be reduced by approximately 1.7° and 2.8° for 4-mm osteotomy and 8-mm osteotomy, respectively. Within the first postoperative year, clinically-stable tibial component subsidence was observed in 9 knees, but it was not progressive, and the clinical results were excellent at a mean follow-up of 3.3 years. Copyright © 2015 Elsevier Inc. All rights reserved.

Ultrasonic evaluation of oxidation and reduction effects on the elastic behavior and global microstructure of YBa2Cu3O7-x

NASA Technical Reports Server (NTRS)

Roth, Don J.; Deguire, Mark R.; Dolhert, Leonard E.

1991-01-01

Ultrasonic velocity measurement techniques were used to evaluate the effects of oxidation and reduction on the elastic properties, global microstructure and oxygen content of the YBa2Cu3O(7-x) ceramic superconductor for samples ranging from 70 to 90 pct. of theoretical density. Bulk density, velocity, and elastic modulus generally increased with increasing oxygen content upon oxidation, and this behavior was reversible. Velocity image patterns were similar after oxidation and reduction treatments for a 90 pct. dense sample, although the velocity value at any given point on the sample was changed following the treatments. The unchanging pattern correlated with destructive measurements showing that the spatial pore distribution (fraction and size) was not measurably altered after the treatments. Changes in superconducting behavior, crystal structure, and grain structure were observed consistent with changes in oxygen content.

Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

PubMed

Libralato, G; Ghirardini, A Volpi; Avezzù, F

2008-05-30

Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

Neo-phalloplasty with re-innervated latissimus dorsi free flap: a functional study of a novel technique.

PubMed

Ranno, R; Veselý, J; Hýza, P; Stupka, I; Justan, I; Dvorák, Z; Monni, N; Novák, P; Ranno, S

2007-01-01

Twenty two patients with gender dysphoria underwent neo-phalloplasties using a novel technique. Latissimus dorsi musculocutaneus re-innervated free flap was used to allow voluntary rigidity of the neo-penis. From the first 22 patients, 18 have obtained motoric function of reconstructed penis; the "paradox erection" was obtained. 14 patients came for examination after a follow-up period of mean 26.4 months. We evaluated the motility and shape changes of neo-phallus measuring its different size and dimension during relax and muscle contraction. The range of neo-phallus length in relaxed position was between 7 and 17 cm (mean 12.2 cm), its circumference in the same position had a range between 13 and 20 cm (mean 13.7 cm). All patients were able to contract the muscle with an average length reduction of 3.08 cm and an average circumference enlargement of 4 cm. In this study, the dimensions and motility were quantified demonstrating the neo-phallus function and size changes during sexual intercourse.

Stahl ear correction using the third crus cartilage flap.

PubMed

Gundeslioglu, A Ozlem; Ince, Bilsev

2013-12-01

Stahl ear is usually associated with the existence of a third crus that traverses the scapha. The absence of the superior crus of the antihelix, a broadened scapha, and unfolded, long helical rim may contribute to the formation of the deformity. The method presented in this article is a combined technique intended to recreate the absent superior crus using the third crus as a cartilage flap along with elimination of the third crus, reducing the scapha size, and correcting helical rim deformities by skin and cartilage excisions. One bilateral and three unilateral cases were operated on with this technique (five auricles). The first unilateral cases were performed without scapha reduction and helix correction which was used in the other three cases with successful results. This procedure can be used to correct Stahl ear variations in the case of an absent superior crus when a third crus is present, the scapha is of increased size, and the helix is long without a fold. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Image compression/decompression based on mathematical transform, reduction/expansion, and image sharpening

DOEpatents

Fu, C.Y.; Petrich, L.I.

1997-12-30

An image represented in a first image array of pixels is first decimated in two dimensions before being compressed by a predefined compression algorithm such as JPEG. Another possible predefined compression algorithm can involve a wavelet technique. The compressed, reduced image is then transmitted over the limited bandwidth transmission medium, and the transmitted image is decompressed using an algorithm which is an inverse of the predefined compression algorithm (such as reverse JPEG). The decompressed, reduced image is then interpolated back to its original array size. Edges (contours) in the image are then sharpened to enhance the perceptual quality of the reconstructed image. Specific sharpening techniques are described. 22 figs.

Embolization of renal angiomyolipomas: short-term and long-term outcomes, complications, and tumor shrinkage.

PubMed

Lee, Shen-Yang; Hsu, Hsiang-Hao; Chen, Yung-Chang; Huang, Chen-Chih; Wong, Yon-Cheong; Wang, Li-Jen; Chuang, Cheng-Keng; Yang, Chih-Wei

2009-11-01

This study retrospectively evaluated outcomes, complications, and tumor shrinkage in renal angiomyolipomas after transcatheter arterial embolization (TAE). All renal angiomyolipoma patients who underwent TAE between August 2000 and December 2008 and had short-term (6 months) follow-up images were evaluated. Complications and tumor relapse after TAE were reviewed. The sizes of embolized tumors were measured to calculate size reductions and reduction rates after TAE. Differences in tumor size, size reduction, and reduction rate between different time points (pre-TAE, short-term follow-up, and long-term follow-up) and groups (completely and incompletely embolized) were determined. Eleven renal angiomyolipoma patients who had undergone TAE were included. Seven (63.6%) patients had postembolization syndrome and one had abscess formation following TAE. Two patients had a tumor relapse (18.2%). The mean tumor size was 8.57+/-2.66 cm on pre-TAE images. The mean size reduction was 3.1 cm (33.3%) and 3.8 cm (43.0%) at short-term and long-term follow-up. Tumor sizes differed significantly between pre-TAE and short-term (p=0.004) or long-term images (p=0.022) but not between short-term and long-term images (p=0.059). Results stratified by the completeness of embolization indicate that only the short-term size reduction rate differed significantly (p=0.025), while the long-term reduction rate and short- and long-term follow-up tumor size and size reduction were comparable between the two groups. In conclusion, selective TAE is effective for tumor shrinkage in most renal angiomyolipomas, with acceptable complication and relapse rates. Tumor shrinkage occurring within 6 months after TAE may reflect the long-term effect of TAE.

Potential dosimetric benefits of adaptive tumor tracking over the internal target volume concept for stereotactic body radiation therapy of pancreatic cancer.

PubMed

Karava, Konstantina; Ehrbar, Stefanie; Riesterer, Oliver; Roesch, Johannes; Glatz, Stefan; Klöck, Stephan; Guckenberger, Matthias; Tanadini-Lang, Stephanie

2017-11-09

Radiotherapy for pancreatic cancer has two major challenges: (I) the tumor is adjacent to several critical organs and, (II) the mobility of both, the tumor and its surrounding organs at risk (OARs). A treatment planning study simulating stereotactic body radiation therapy (SBRT) for pancreatic tumors with both the internal target volume (ITV) concept and the tumor tracking approach was performed. The two respiratory motion-management techniques were compared in terms of doses to the target volume and organs at risk. Two volumetric-modulated arc therapy (VMAT) treatment plans (5 × 5 Gy) were created for each of the 12 previously treated pancreatic cancer patients, one using the ITV concept and one the tumor tracking approach. To better evaluate the overall dose delivered to the moving tumor volume, 4D dose calculations were performed on four-dimensional computed tomography (4DCT) scans. The resulting planning target volume (PTV) size for each technique was analyzed. Target and OAR dose parameters were reported and analyzed for both 3D and 4D dose calculation. Tumor motion ranged from 1.3 to 11.2 mm. Tracking led to a reduction of PTV size (max. 39.2%) accompanied with significant better tumor coverage (p<0.05, paired Wilcoxon signed rank test) both in 3D and 4D dose calculations and improved organ at risk sparing. Especially for duodenum, stomach and liver, the mean dose was significantly reduced (p<0.05) with tracking for 3D and 4D dose calculations. By using an adaptive tumor tracking approach for respiratory-induced pancreatic motion management, a significant reduction in PTV size can be achieved, which subsequently facilitates treatment planning, and improves organ dose sparing. The dosimetric benefit of tumor tracking is organ and patient-specific.

Implications for earthquake risk reduction in the United States from the Kocaeli, Turkey, earthquake of August 17, 1999

USGS Publications Warehouse

,

2000-01-01

This report documents implications for earthquake risk reduction in the U.S. The magnitude 7.4 earthquake caused 17,127 deaths, 43,953 injuries, and displaced more than 250,000 people from their homes. The report warns that similar disasters are possible in the United States where earthquakes of comparable size strike the heart of American urban areas. Another concern described in the report is the delayed emergency response that was caused by the inadequate seismic monitoring system in Turkey, a problem that contrasts sharply with rapid assessment and response to the September Chi-Chi earthquake in Taiwan. Additionally, the experience in Turkey suggests that techniques for forecasting earthquakes may be improving.

Effects of Planetary Gear Ratio on Mean Service Life

NASA Technical Reports Server (NTRS)

Savage, M.; Rubadeux, K. L.; Coe, H. H.

1996-01-01

Planetary gear transmissions are compact, high-power speed reductions which use parallel load paths. The range of possible reduction ratios is bounded from below and above by limits on the relative size of the planet gears. For a single plane transmission, the planet gear has no size at a ratio of two. As the ratio increases, so does the size of the planets relative to the sizes of the sun and ring. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal designs. In this series, each design is obtained by maximizing the service life for a planetary with a fixed size, gear ratio, input speed power and materials. The planetary gear reduction service life is modeled as a function of the two-parameter Weibull distributed service lives of the bearings and gears in the reduction. Planet bearing life strongly influences the optimal reduction lives which point to an optimal planetary reduction ratio in the neighborhood of four to five.

Roles of size and kinematics in drag reduction for two tandem flexible foils

NASA Astrophysics Data System (ADS)

Chao, Li-Ming; Zhang, Dong; Pan, Guang

2017-11-01

The effect of size and kinematics difference between two tandem flexible foils on drag reduction have been numerically studied. Compared with single foil, it is found that the kinematics difference between two foils would not play a significant role in reducing drag, while the size difference between two foils significantly affects the drag reduction in this two foil system. For leading foil, it always enjoys drag reduction and the highest drag reduction can be observed at bigger size difference and gap distance between two foil as 22%. For trailing foil, it suffers drag increase when the gap distance between two foils is smaller, while it enjoys drag decrease when the size difference between two foils is bigger enough. The hydrodynamic interaction between such actively undulated foils also has been uncovered and used to explain the mechanisms of drag reduction.

Widespread rapid reductions in body size of adult salamanders in response to climate change.

PubMed

Caruso, Nicholas M; Sears, Michael W; Adams, Dean C; Lips, Karen R

2014-06-01

Reduction in body size is a major response to climate change, yet evidence in globally imperiled amphibians is lacking. Shifts in average population body size could indicate either plasticity in the growth response to changing climates through changes in allocation and energetics, or through selection for decreased size where energy is limiting. We compared historic and contemporary size measurements in 15 Plethodon species from 102 populations (9450 individuals) and found that six species exhibited significant reductions in body size over 55 years. Biophysical models, accounting for actual changes in moisture and air temperature over that period, showed a 7.1-7.9% increase in metabolic expenditure at three latitudes but showed no change in annual duration of activity. Reduced size was greatest at southern latitudes in regions experiencing the greatest drying and warming. Our results are consistent with a plastic response of body size to climate change through reductions in body size as mediated through increased metabolism. These rapid reductions in body size over the past few decades have significance for the susceptibility of amphibians to environmental change, and relevance for whether adaptation can keep pace with climate change in the future. © 2014 John Wiley & Sons Ltd.

The effect of various parameters of large scale radio propagation models on improving performance mobile communications

NASA Astrophysics Data System (ADS)

Pinem, M.; Fauzi, R.

2018-02-01

One technique for ensuring continuity of wireless communication services and keeping a smooth transition on mobile communication networks is the soft handover technique. In the Soft Handover (SHO) technique the inclusion and reduction of Base Station from the set of active sets is determined by initiation triggers. One of the initiation triggers is based on the strong reception signal. In this paper we observed the influence of parameters of large-scale radio propagation models to improve the performance of mobile communications. The observation parameters for characterizing the performance of the specified mobile system are Drop Call, Radio Link Degradation Rate and Average Size of Active Set (AS). The simulated results show that the increase in altitude of Base Station (BS) Antenna and Mobile Station (MS) Antenna contributes to the improvement of signal power reception level so as to improve Radio Link quality and increase the average size of Active Set and reduce the average Drop Call rate. It was also found that Hata’s propagation model contributed significantly to improvements in system performance parameters compared to Okumura’s propagation model and Lee’s propagation model.

Morphometric changes of Triatoma flavida Neiva, 1911 (Hemiptera:Triatominae) in the transition from sylvatic to laboratory conditions.

PubMed

Rodríguez Rodríguez, Jinnay; Fuentes González, Omar; Nodarse, Jorge Fraga; Monzote Fidalgo, Lianet; Dujardin, Jean-Pierre

2007-01-01

The one-generational metric changes occurring in Triatoma flavida (Hemiptera: Triatominae) when carried from its wild habitat (caves) to laboratory, were examined using traditional morphometric techniques. As for other species of Triatoma, Rhodnius or Panstrongylus studied in similar conditions, a significant reduction of head, thorax and wing size was observed. Sexual dimorphism of the wings, while present in the wild sample, was not detected anymore in the laboratory individuals. Biological significance and epidemiological importance are discussed.

Fabrication of High Energy Density Tin/Carbon Anode Using Reduction Expansion Synthesis and Aerosol Through Plasma Techniques

DTIC Science & Technology

2017-03-01

lithium - ion and sodium- ion batteries , respectively. Nano-sized Sn particles were found before and after cycling. It is believed that bonds between...The use of the electrodes as part of coin cell batteries resulted in capacitance values of 320 mAh/g and 110 mAh/g for lithium - ion and sodium- ion ...63  1.  Potential Increase in Capacity from Lithium - ion Batteries .....63  2.  Reduced Reliance on Lithium - ion Batteries

Fabrication of High Energy Density Tin/Carbon Anode Using Reduction Expansion Synthesis and Aerosol through Plasma Techniques

DTIC Science & Technology

2017-03-01

lithium - ion and sodium- ion batteries , respectively. Nano-sized Sn particles were found before and after cycling. It is believed that bonds between...The use of the electrodes as part of coin cell batteries resulted in capacitance values of 320 mAh/g and 110 mAh/g for lithium - ion and sodium- ion ...63  1.  Potential Increase in Capacity from Lithium - ion Batteries .....63  2.  Reduced Reliance on Lithium - ion Batteries

Using What We Know: A Review of the Research on Implementing Class-Size Reduction Initiatives for State and Local Policymakers.

ERIC Educational Resources Information Center

Laine, Sabrina W. M., Ed.; Ward, James G., Ed.

This book contains a collection of essays involving new research on class-size reduction. Six chapters include: (1) "Reducing Class Size in Public Schools: Cost-Benefit Issues and Implications" (John F. Witte); (2) "Making Policy Choices: Is Class-Size Reduction the Best Alternative?" (Doug Harris and David N. Plank); (3) "Smaller Classes, Lower…

Forced-air warming: a source of airborne contamination in the operating room?

PubMed

Albrecht, Mark; Gauthier, Robert; Leaper, David

2009-10-10

Forced-air-warming (FAW) is an effective and widely used means for maintaining surgical normothermia, but FAW also has the potential to generate and mobilize airborne contamination in the operating room.We measured the emission of viable and non-viable forms of airborne contamination from an arbitrary selection of FAW blowers (n=25) in the operating room. A laser particle counter measured particulate concentrations of the air near the intake filter and in the distal hose airstream. Filtration efficiency was calculated as the reduction in particulate concentration in the distal hose airstream relative to that of the intake. Microbial colonization of the FAW blower's internal hose surfaces was assessed by culturing the microorganisms recovered through swabbing (n=17) and rinsing (n=9) techniques.Particle counting revealed that 24% of FAW blowers were emitting significant levels of internally generated airborne contamination in the 0.5 to 5.0 µm size range, evidenced by a steep decrease in FAW blower filtration efficiency for particles 0.5 to 5.0 µm in size. The particle size-range-specific reduction in efficiency could not be explained by the filtration properties of the intake filter. Instead, the reduction was found to be caused by size-range-specific particle generation within the FAW blowers. Microorganisms were detected on the internal air path surfaces of 94% of FAW blowers.The design of FAW blowers was found to be questionable for preventing the build-up of internal contamination and the emission of airborne contamination into the operating room. Although we did not evaluate the link between FAW and surgical site infection rates, a significant percentage of FAW blowers with positive microbial cultures were emitting internally generated airborne contamination within the size range of free floating bacteria and fungi (<4 µm) that could, conceivably, settle onto the surgical site.

An implicit scheme with memory reduction technique for steady state solutions of DVBE in all flow regimes

NASA Astrophysics Data System (ADS)

Yang, L. M.; Shu, C.; Yang, W. M.; Wu, J.

2018-04-01

High consumption of memory and computational effort is the major barrier to prevent the widespread use of the discrete velocity method (DVM) in the simulation of flows in all flow regimes. To overcome this drawback, an implicit DVM with a memory reduction technique for solving a steady discrete velocity Boltzmann equation (DVBE) is presented in this work. In the method, the distribution functions in the whole discrete velocity space do not need to be stored, and they are calculated from the macroscopic flow variables. As a result, its memory requirement is in the same order as the conventional Euler/Navier-Stokes solver. In the meantime, it is more efficient than the explicit DVM for the simulation of various flows. To make the method efficient for solving flow problems in all flow regimes, a prediction step is introduced to estimate the local equilibrium state of the DVBE. In the prediction step, the distribution function at the cell interface is calculated by the local solution of DVBE. For the flow simulation, when the cell size is less than the mean free path, the prediction step has almost no effect on the solution. However, when the cell size is much larger than the mean free path, the prediction step dominates the solution so as to provide reasonable results in such a flow regime. In addition, to further improve the computational efficiency of the developed scheme in the continuum flow regime, the implicit technique is also introduced into the prediction step. Numerical results showed that the proposed implicit scheme can provide reasonable results in all flow regimes and increase significantly the computational efficiency in the continuum flow regime as compared with the existing DVM solvers.

Image analysis for quantification of bacterial rock weathering.

PubMed

Puente, M Esther; Rodriguez-Jaramillo, M Carmen; Li, Ching Y; Bashan, Yoav

2006-02-01

A fast, quantitative image analysis technique was developed to assess potential rock weathering by bacteria. The technique is based on reduction in the surface area of rock particles and counting the relative increase in the number of small particles in ground rock slurries. This was done by recording changes in ground rock samples with an electronic image analyzing process. The slurries were previously amended with three carbon sources, ground to a uniform particle size and incubated with rock weathering bacteria for 28 days. The technique was developed and tested, using two rock-weathering bacteria Pseudomonas putida R-20 and Azospirillum brasilense Cd on marble, granite, apatite, quartz, limestone, and volcanic rock as substrates. The image analyzer processed large number of particles (10(7)-10(8) per sample), so that the weathering capacity of bacteria can be detected.

Selectivity of photoelectrochemical CO2 reduction modulated with electron transfer from size-tunable quantized energy states of CdSe nanocrystals

NASA Astrophysics Data System (ADS)

Cho, Hyunjin; Kim, Whi Dong; Lee, Kangha; Lee, Seokwon; Kang, Gil-Seong; Joh, Han-Ik; Lee, Doh C.

2018-01-01

We investigate the product selectivity of CO2 reduction using NiO photocathodes decorated with CdSe quantum dots (QDs) of varying size in a photoelectrochemical (PEC) cell. Size-tunable and quantized energy states of conduction band in CdSe QDs enable systematic control of electron transfer kinetics from CdSe QDs to NiO. It turns out that different size of CdSe QDs results in variation in product selectivity for CO2 reduction. The energy gap between conduction band edge and redox potential of each reduction product (e.g., CO and CH4) correlates with their production rate. The size dependence of the electron transfer rate estimated from the energy gap is in agreement with the selectivity of CO2 reduction products for all reduction products but CO. The deviation in the case of CO is attributed to sequential conversion of CO into CH4 with CO adsorbed on electrode surface. Based on a premise that the CdSe QDs would exhibit similar surface configuration regardless of QD size, it is concluded that the electron transfer kinetics proves to alter the selectivity of CO2 reduction.

Vertical Object Layout and Compression for Fixed Heaps

NASA Astrophysics Data System (ADS)

Titzer, Ben L.; Palsberg, Jens

Research into embedded sensor networks has placed increased focus on the problem of developing reliable and flexible software for microcontroller-class devices. Languages such as nesC [10] and Virgil [20] have brought higher-level programming idioms to this lowest layer of software, thereby adding expressiveness. Both languages are marked by the absence of dynamic memory allocation, which removes the need for a runtime system to manage memory. While nesC offers code modules with statically allocated fields, arrays and structs, Virgil allows the application to allocate and initialize arbitrary objects during compilation, producing a fixed object heap for runtime. This paper explores techniques for compressing fixed object heaps with the goal of reducing the RAM footprint of a program. We explore table-based compression and introduce a novel form of object layout called vertical object layout. We provide experimental results that measure the impact on RAM size, code size, and execution time for a set of Virgil programs. Our results show that compressed vertical layout has better execution time and code size than table-based compression while achieving more than 20% heap reduction on 6 of 12 benchmark programs and 2-17% heap reduction on the remaining 6. We also present a formalization of vertical object layout and prove tight relationships between three styles of object layout.

Compression-based aggregation model for medical web services.

PubMed

Al-Shammary, Dhiah; Khalil, Ibrahim

2010-01-01

Many organizations such as hospitals have adopted Cloud Web services in applying their network services to avoid investing heavily computing infrastructure. SOAP (Simple Object Access Protocol) is the basic communication protocol of Cloud Web services that is XML based protocol. Generally,Web services often suffer congestions and bottlenecks as a result of the high network traffic that is caused by the large XML overhead size. At the same time, the massive load on Cloud Web services in terms of the large demand of client requests has resulted in the same problem. In this paper, two XML-aware aggregation techniques that are based on exploiting the compression concepts are proposed in order to aggregate the medical Web messages and achieve higher message size reduction.

Optimizing Aspect-Oriented Mechanisms for Embedded Applications

NASA Astrophysics Data System (ADS)

Hundt, Christine; Stöhr, Daniel; Glesner, Sabine

As applications for small embedded mobile devices are getting larger and more complex, it becomes inevitable to adopt more advanced software engineering methods from the field of desktop application development. Aspect-oriented programming (AOP) is a promising approach due to its advanced modularization capabilities. However, existing AOP languages tend to add a substantial overhead in both execution time and code size which restricts their practicality for small devices with limited resources. In this paper, we present optimizations for aspect-oriented mechanisms at the level of the virtual machine. Our experiments show that these optimizations yield a considerable performance gain along with a reduction of the code size. Thus, our optimizations establish the base for using advanced aspect-oriented modularization techniques for developing Java applications on small embedded devices.

Comparing and contrasting poverty reduction performance of social welfare programs across jurisdictions in Canada using Data Envelopment Analysis (DEA): an exploratory study of the era of devolution.

PubMed

Habibov, Nazim N; Fan, Lida

2010-11-01

In the mid-1990s, the responsibilities to design, implement, and evaluate social welfare programs were transferred from federal to local jurisdictions in many countries of North America and Europe through devolution processes. Devolution has caused the need for a technique to measure and compare the performances of social welfare programs across multiple jurisdictions. This paper utilizes Data Envelopment Analysis (DEA) for a comparison of poverty reduction performances of jurisdictional social welfare programs across Canadian provinces. From the theoretical perspective, findings of this paper demonstrates that DEA is a promising method to evaluate, compare, and benchmark poverty reduction performance across multiple jurisdictions using multiple inputs and outputs. This paper demonstrates that DEA generates easy to comprehend composite rankings of provincial performances, identifies appropriate benchmarks for each inefficient province, and estimates sources and amounts of improvement needed to make the provinces efficient. From a practical perspective the empirical results presented in this paper indicate that Newfoundland, Prince Edwards Island, and Alberta achieve better efficiency in poverty reduction than other provinces. Policy makers and social administrators of the ineffective provinces across Canada may find benefit in selecting one of the effective provinces as a benchmark for improving their own performance based on similar size and structure of population, size of the budget for social programs, and traditions with administering particular types of social programs. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Wing download reduction using vortex trapping plates

NASA Technical Reports Server (NTRS)

Light, Jeffrey S.; Stremel, Paul M.; Bilanin, Alan J.

1994-01-01

A download reduction technique using spanwise plates on the upper and lower wing surfaces has been examined. Experimental and analytical techniques were used to determine the download reduction obtained using this technique. Simple two-dimensional wind tunnel testing confirmed the validity of the technique for reducing two-dimensional airfoil drag. Computations using a two-dimensional Navier-Stokes analysis provided insight into the mechanism causing the drag reduction. Finally, the download reduction technique was tested using a rotor and wing to determine the benefits for a semispan configuration representative of a tilt rotor aircraft.

Quantifying carbon footprint reduction opportunities for U.S. households and communities.

PubMed

Jones, Christopher M; Kammen, Daniel M

2011-05-01

Carbon management is of increasing interest to individuals, households, and communities. In order to effectively assess and manage their climate impacts, individuals need information on the financial and greenhouse gas benefits of effective mitigation opportunities. We use consumption-based life cycle accounting techniques to quantify the carbon footprints of typical U.S. households in 28 cities for 6 household sizes and 12 income brackets. The model includes emissions embodied in transportation, energy, water, waste, food, goods, and services. We further quantify greenhouse gas and financial savings from 13 potential mitigation actions across all household types. The model suggests that the size and composition of carbon footprints vary dramatically between geographic regions and within regions based on basic demographic characteristics. Despite these differences, large cash-positive carbon footprint reductions are evident across all household types and locations; however, realizing this potential may require tailoring policies and programs to different population segments with very different carbon footprint profiles. The results of this model have been incorporated into an open access online carbon footprint management tool designed to enable behavior change at the household level through personalized feedback.

Biosynthesis of silver nanoparticles by using Ganoderma-mushroom extract

NASA Astrophysics Data System (ADS)

Ekar, S. U.; Khollam, Y. B.; Koinkar, P. M.; Mirji, S. A.; Mane, R. S.; Naushad, M.; Jadhav, S. S.

2015-03-01

Present study reports the biochemical synthesis of silver nanoparticles (Ag-NPs) from aqueous medium by using the extract of medicinal mushroom Ganoderma, as a reducing and stabilizing agents. The Ag-NPs are prepared at room temperature by the reduction of Ag+ to Ag in aqueous solution of AgNO3. The resultant particles are characterized by using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) measurement techniques. The formation of Ag-NPs is confirmed by recording the UV-visible absorption spectra for surface plasmon resonance (SPR) where peak around 427 nm. The prominent changes observed in FTIR spectra supported the reduction of Ag+ to Ag. The morphological features of Ag-NPs are evaluated from HRTEM. The spherical Ag-NPs are observed in transmission electron microscopy (TEM) studies. The particle size distribution is found to be nearly uniform with average particle size of 2 nm. The Ag-NPs aged for 15, 30, 60 and 120 days showed no profound effect on the position of SPR peak in UV-visible studies, indicating the protecting/capping ability of medicinal mushroom Ganoderma in the synthesis of Ag-NPs.

Comparative catalytic reduction of 4-nitrophenol by polyacrylamide-gold nanocomposite synthesized by hydrothermal autoclaving and conventional heating routes

NASA Astrophysics Data System (ADS)

Salaheldin, Hosam I.

2017-12-01

Gold nanoparticles (AuNPs) in polymeric polyacrylamide (PAAm) matrix were synthesized using conventional heating and autoclaving thermal techniques. The synthesized Au/PAAm nanocomposite was characterized using UV-vis spectroscopy and high-resolution transmission electron microscopy. The size of the synthesized particles was approximately 6.37 nm and 8.19 nm with the conventional heating and autoclaving thermal techniques, respectively. Electron diffraction x-ray spectroscopy and the Fourier transformation infrared spectroscopy were used for the composition and elemental studies, which confirmed that the Au metallic atoms were synthesized and embedded within a PAAm matrix via a coordination bond between the carbonyl (-CONH2) group and the metallic NPs. X-ray diffraction confirmed the crystalline nature of the fabricated AuNPs with face centered cubic of nanocrystals. The catalytic activity of the as-prepared Au/PAAm nanocomposite for the reduction of 4-nitrophenol to 4-aminophenol was studied in the presence of sodium borohydrate. The synthesized AuNPs had an effective catalytic activity; the smaller NPs synthesized NPs with the conventional heating technique had a higher reaction kinetic rate in comparation with those synthesized with the autoclaving technique. Therefore, the Au/PAAm nanocomposite can be widely used as an eco-friendly, non-toxic, a fast and cost-effective product to remove versatile organic pollutants such as aromatic nitro compounds.

Preparation and characterization of maghemite nanoparticles from mild steel for magnetically guided drug therapy.

PubMed

Kumar, Nitesh; Kulkarni, Kaustubh; Behera, Laxmidhar; Verma, Vivek

2017-08-01

Maghemite (γ-Fe 2 O 3 ) nanoparticles for therapeutic applications are prepared from mild steel but the existing synthesis technique is very cumbersome. The entire process takes around 100 days with multiple steps which lack proper understanding. In the current work, maghemite nanoparticles of cuboidal and spheroidal morphologies were prepared from mild steel chips by a novel cost effective oil reduction technique for magnetically guided intravascular drug delivery. The technique developed in this work yields isometric sized γ-Fe 2 O 3 nanoparticles in 6 h with higher saturation magnetization as compared to the existing similar solid state synthesis route. Mass and heat flow kinetics during the heating and quenching steps were studied with the help of Finite element simulations. Qualitative and quantitative analysis of the γ-Fe 2 O 3 phase is performed with the help of x-ray diffraction, transmission electron microscope and x-ray photoelectron spectroscopy. Mechanism for the α-Fe 2 O 3 (haematite) to γ-Fe 2 O 3 (maghemite) phase evolution during the synthesis process is also investigated. Maghemite (γ-Fe 2 O 3 ) nanoparticles were prepared bya novel cost effective oil reduction technique as mentioned below in the figure. The raw materials included mild steel chips which is one of the most abundant engineering materials. These particles can be used as ideal nanocarriers for targeted drug delivery through the vascular network.

Enhanced Solubility and Dissolution Rate of Lacidipine Nanosuspension: Formulation Via Antisolvent Sonoprecipitation Technique and Optimization Using Box-Behnken Design.

PubMed

Kassem, Mohamed A A; ElMeshad, Aliaa N; Fares, Ahmed R

2017-05-01

Lacidipine (LCDP) is a highly lipophilic calcium channel blocker of poor aqueous solubility leading to poor oral absorption. This study aims to prepare and optimize LCDP nanosuspensions using antisolvent sonoprecipitation technique to enhance the solubility and dissolution of LCDP. A three-factor, three-level Box-Behnken design was employed to optimize the formulation variables to obtain LCDP nanosuspension of small and uniform particle size. Formulation variables were as follows: stabilizer to drug ratio (A), sodium deoxycholate percentage (B), and sonication time (C). LCDP nanosuspensions were assessed for particle size, zeta potential, and polydispersity index. The formula with the highest desirability (0.969) was chosen as the optimized formula. The values of the formulation variables (A, B, and C) in the optimized nanosuspension were 1.5, 100%, and 8 min, respectively. Optimal LCDP nanosuspension had particle size (PS) of 273.21 nm, zeta potential (ZP) of -32.68 mV and polydispersity index (PDI) of 0.098. LCDP nanosuspension was characterized using x-ray powder diffraction, differential scanning calorimetry, and transmission electron microscopy. LCDP nanosuspension showed saturation solubility 70 times that of raw LCDP in addition to significantly enhanced dissolution rate due to particle size reduction and decreased crystallinity. These results suggest that the optimized LCDP nanosuspension could be promising to improve oral absorption of LCDP.

Proteoglycan depletion and size reduction in lesions of early grade chondromalacia of the patella.

PubMed

Väätäinen, U; Häkkinen, T; Kiviranta, I; Jaroma, H; Inkinen, R; Tammi, M

1995-10-01

To determine the content and molecular size of proteoglycans (PGs) in patellar chondromalacia (CM) and control cartilages as a first step in investigating the role of matrix alterations in the pathogenesis of this disease. Chondromalacia tissue from 10 patients was removed with a surgical knife. Using identical techniques, apparently healthy cartilage of the same site was obtained from 10 age matched cadavers (mean age 31 years in both groups). Additional pathological cartilage was collected from 67 patients with grades II-IV CM (classified according to Outerbridge) using a motorised shaver under arthroscopic control. The shaved cartilage chips were collected with a dense net from the irrigation fluid of the shaver. The content of tissue PGs was determined by Safranin O precipitation or uronic acid content, and the molecular size by mobility on agarose gel electrophoresis. The mean PG content of the CM tissue samples with a knife was dramatically reduced, being only 15% of that in controls. The cartilage chips collected from shaving operations of grades II, III, and IV CM showed a decreasing PG content: 9%, 5%, and 1% of controls, respectively. Electrophoretic analysis of PGs extracted with guanidium chloride from the shaved tissue samples suggested a significantly reduced size of aggrecans in the mild (grade II) lesions. These data show that there is already a dramatic and progressive depletion of PGs in CM grade II lesions. This explains the softening of cartilage, a typical finding in the arthroscopic examination of CM. The PG size reduction observed in grade II implicates proteolytic attack as a factor in the pathogenesis of CM.

Milch versus Stimson technique for nonsedated reduction of anterior shoulder dislocation: a prospective randomized trial and analysis of factors affecting success.

PubMed

Amar, Eyal; Maman, Eran; Khashan, Morsi; Kauffman, Ehud; Rath, Ehud; Chechik, Ofir

2012-11-01

The shoulder is regarded as the most commonly dislocated major joint in the human body. Most dislocations can be reduced by simple methods in the emergency department, whereas others require more complicated approaches. We compared the efficacy, safety, pain, and duration of the reduction between the Milch technique and the Stimson technique in treating dislocations. We also identified factors that affected success rate. All enrolled patients were randomized to either the Milch technique or the Stimson technique for dislocated shoulder reduction. The study cohort consisted of 60 patients (mean age, 43.9 years; age range, 18-88 years) who were randomly assigned to treatment by either the Stimson technique (n = 25) or the Milch technique (n = 35). Oral analgesics were available for both groups. The 2 groups were similar in demographics, patient characteristics, and pain levels. The first reduction attempt in the Milch and Stimson groups was successful in 82.8% and 28% of cases, respectively (P < .001), and the mean reduction time was 4.68 and 8.84 minutes, respectively (P = .007). The success rate was found to be affected by the reduction technique, the interval between dislocation occurrence and first reduction attempt, and the pain level on admittance. The success rate and time to achieve reduction without sedation were superior for the Milch technique compared with the Stimson technique. Early implementation of reduction measures and low pain levels at presentation favor successful reduction, which--in combination with oral pain medication--constitutes an acceptable and reasonable management alternative to reduction with sedation. Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

In situ SAXS study on size changes of platinum nanoparticles with temperature

NASA Astrophysics Data System (ADS)

Wang, W.; Chen, X.; Cai, Q.; Mo, G.; Jiang, L. S.; Zhang, K.; Chen, Z. J.; Wu, Z. H.; Pan, W.

2008-09-01

Poly(vinylpyrrolidone) (PVP)-coated platinum (Pt) nanoparticles were prepared in methanol-water reduction method. In situ small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) techniques were used to probe the size change of particles and crystallites with temperature. Tangent-by-tangent (TBT) method of SAXS data analysis was improved and used to get the particle size distribution (PSD) from SAXS intensity. Scherrer’s equation was used to derive the crystallite size from XRD pattern. Combining SAXS and XRD results, a step-like characteristic of the Pt nanoparticle growth has been found. Three stages (diffusion, aggregation, and agglomeration) can be used to describe the growth of the Pt nanoparticles and nanocrystallites. Aggregation was found to be the main growth mode of the Pt nanoparticles during heating. The maximum growth rates of Pt nanoparticles and Pt nanocrystallites, as well as the maximum aggregation degree of Pt nanocrystallites were found, respectively, at 250 °C, 350 °C and 300 °C. These results are helpful to understanding the growth mode of nanoparticles, as well as controlling the nanoparticle size.

How chip size impacts steam pretreatment effectiveness for biological conversion of poplar wood into fermentable sugars

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeMartini, Jaclyn D.; Foston, Marcus; Meng, Xianzhi

We report that woody biomass is highly recalcitrant to enzymatic sugar release and often requires significant size reduction and severe pretreatments to achieve economically viable sugar yields in biological production of sustainable fuels and chemicals. However, because mechanical size reduction of woody biomass can consume significant amounts of energy, it is desirable to minimize size reduction and instead pretreat larger wood chips prior to biological conversion. To date, however, most laboratory research has been performed on materials that are significantly smaller than applicable in a commercial setting. As a result, there is a limited understanding of the effects that largermore » biomass particle size has on the effectiveness of steam explosion pretreatment and subsequent enzymatic hydrolysis of wood chips. To address these concerns, novel downscaled analysis and high throughput pretreatment and hydrolysis (HTPH) were applied to examine whether differences exist in the composition and digestibility within a single pretreated wood chip due to heterogeneous pretreatment across its thickness. Heat transfer modeling, Simons’ stain testing, magnetic resonance imaging (MRI), and scanning electron microscopy (SEM) were applied to probe the effects of pretreatment within and between pretreated wood samples to shed light on potential causes of variation, pointing to enzyme accessibility (i.e., pore size) distribution being a key factor dictating enzyme digestibility in these samples. Application of these techniques demonstrated that the effectiveness of pretreatment of Populus tremuloides can vary substantially over the chip thickness at short pretreatment times, resulting in spatial digestibility effects and overall lower sugar yields in subsequent enzymatic hydrolysis. Finally, these results indicate that rapid decompression pretreatments (e.g., steam explosion) that specifically alter accessibility at lower temperature conditions are well suited for larger wood chips due to the non-uniformity in temperature and digestibility profiles that can result from high temperature and short pretreatment times. Furthermore, this study also demonstrated that wood chips were hydrated primarily through the natural pore structure during pretreatment, suggesting that preserving the natural grain and transport systems in wood during storage and chipping processes could likely promote pretreatment efficacy and uniformity.« less

How chip size impacts steam pretreatment effectiveness for biological conversion of poplar wood into fermentable sugars

DOE PAGES

DeMartini, Jaclyn D.; Foston, Marcus; Meng, Xianzhi; ...

2015-12-09

We report that woody biomass is highly recalcitrant to enzymatic sugar release and often requires significant size reduction and severe pretreatments to achieve economically viable sugar yields in biological production of sustainable fuels and chemicals. However, because mechanical size reduction of woody biomass can consume significant amounts of energy, it is desirable to minimize size reduction and instead pretreat larger wood chips prior to biological conversion. To date, however, most laboratory research has been performed on materials that are significantly smaller than applicable in a commercial setting. As a result, there is a limited understanding of the effects that largermore » biomass particle size has on the effectiveness of steam explosion pretreatment and subsequent enzymatic hydrolysis of wood chips. To address these concerns, novel downscaled analysis and high throughput pretreatment and hydrolysis (HTPH) were applied to examine whether differences exist in the composition and digestibility within a single pretreated wood chip due to heterogeneous pretreatment across its thickness. Heat transfer modeling, Simons’ stain testing, magnetic resonance imaging (MRI), and scanning electron microscopy (SEM) were applied to probe the effects of pretreatment within and between pretreated wood samples to shed light on potential causes of variation, pointing to enzyme accessibility (i.e., pore size) distribution being a key factor dictating enzyme digestibility in these samples. Application of these techniques demonstrated that the effectiveness of pretreatment of Populus tremuloides can vary substantially over the chip thickness at short pretreatment times, resulting in spatial digestibility effects and overall lower sugar yields in subsequent enzymatic hydrolysis. Finally, these results indicate that rapid decompression pretreatments (e.g., steam explosion) that specifically alter accessibility at lower temperature conditions are well suited for larger wood chips due to the non-uniformity in temperature and digestibility profiles that can result from high temperature and short pretreatment times. Furthermore, this study also demonstrated that wood chips were hydrated primarily through the natural pore structure during pretreatment, suggesting that preserving the natural grain and transport systems in wood during storage and chipping processes could likely promote pretreatment efficacy and uniformity.« less

Investigating the effect of pixel size of high spatial resolution FTIR imaging for detection of colorectal cancer

NASA Astrophysics Data System (ADS)

Lloyd, G. R.; Nallala, J.; Stone, N.

2016-03-01

FTIR is a well-established technique and there is significant interest in applying this technique to medical diagnostics e.g. to detect cancer. The introduction of focal plane array (FPA) detectors means that FTIR is particularly suited to rapid imaging of biopsy sections as an adjunct to digital pathology. Until recently however each pixel in the image has been limited to a minimum of 5.5 µm which results in a comparatively low magnification image or histology applications and potentially the loss of important diagnostic information. The recent introduction of higher magnification optics gives image pixels that cover approx. 1.1 µm. This reduction in image pixel size gives images of higher magnification and improved spatial detail can be observed. However, the effect of increasing the magnification on spectral quality and the ability to discriminate between disease states is not well studied. In this work we test the discriminatory performance of FTIR imaging using both standard (5.5 µm) and high (1.1 µm) magnification for the detection of colorectal cancer and explore the effect of binning to degrade high resolution images to determine whether similar diagnostic information and performance can be obtained using both magnifications. Results indicate that diagnostic performance using high magnification may be reduced as compared to standard magnification when using existing multivariate approaches. Reduction of the high magnification data to standard magnification via binning can potentially recover some of the lost performance.

Conversion of transuranic waste to low level waste by decontamination: a technical and economic evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, R.P.; Hazelton, R.F.

1984-12-01

A study was conducted to evaluate the technical and economic feasibility of using in-situ decontamination techniques to convert glove boxes and other large TRU-contaminated components directly into LLW. The results of the technical evaluation indicate that in-situ decontamination of these types of components to non-TRU levels is technically feasible. Applicable decontamination techniques include electropolishing, hand scrubbing, chemical washes/sprays, strippable coatings and Freon spray-cleaning. The removal of contamination from crevices and other holdup areas remains a problem, but may be solved through further advances in decontamination technology. Also, the increase in the allowable maximum TRU level from 10 nCi/g to 100more » nCi/g as defined in DOE Order 5820.2 reduces the removal requirement and facilitates measurement of the remaining quantities. The major emphasis of the study was on a cost/benefit evaluation that included a review and update of previous analyses and evaluations of TRU-waste volume reduction and conversion options. The results of the economic evaluation show, for the assumptions used, that there is a definite cost incentive to size reduce large components, and that decontamination of sectioned material has become cost competitive with the size reduction options. In-situ decontamination appears to be the lowest cost option when based on routine-type operations conducted by well-trained and properly equipped personnel. 16 references, 1 figure, 7 tables.« less

Class Size Reduction in Practice: Investigating the Influence of the Elementary School Principal

ERIC Educational Resources Information Center

Burch, Patricia; Theoharis, George; Rauscher, Erica

2010-01-01

Class size reduction (CSR) has emerged as a very popular, if not highly controversial, policy approach for reducing the achievement gap. This article reports on findings from an implementation study of class size reduction policy in Wisconsin entitled the Student Achievement Guarantee in Education (SAGE). Drawing on case studies of nine schools,…

Note: An approach to 1000 T using the electro-magnetic flux compression.

PubMed

Nakamura, D; Sawabe, H; Takeyama, S

2018-01-01

The maximum magnetic field obtained by the electro-magnetic flux compression technique was investigated with respect to the initial seed magnetic field. It was found that the reduction in the seed magnetic field from 3.8 T to 3.0 T led to a substantial increase in the final peak magnetic field. The optical Faraday rotation method with a minimal size probe evades disturbances from electromagnetic noise and shockwave effects to detect such final peak fields in a reduced space of an inner wall of the imploding liner. The Faraday rotation signal recorded the maximum magnetic field increased significantly to the highest magnetic field of 985 T approaching 1000 T, ever achieved by the electro-magnetic flux compression technique as an indoor experiment.

Experimental techniques for studying the structure of foams and froths.

PubMed

Pugh, R J

2005-06-30

Several techniques are described in this review to study the structure and the stability of froths and foams. Image analysis proved useful for detecting structure changes in 2-D foams and has enabled the drainage process and the gradients in bubble size distribution to be determined. However, studies on 3-D foams require more complex techniques such as Multiple-Light Scattering Methods, Microphones and Optical Tomography. Under dynamic foaming conditions, the Foam Scan Column enables the water content of foams to be determined by conductivity analysis. It is clear that the same factors, which play a role in foam stability (film thickness, elasticity, etc.) also have a decisive influence on the stability of isolated froth or foam films. Therefore, the experimental thin film balance (developed by the Bulgarian Researchers) to study thinning of microfilms formed by a concave liquid drop suspended in a short vertical capillary tube has proved useful. Direct measurement of the thickness of the aqueous microfilm is determined by a micro-reflectance method and can give fundamental information on drainage and thin film stability. It is also important to consider the influence of the mineral particles on the stability of the froth and it have been shown that particles of well defined size and hydrophobicity can be introduced into the thin film enabling stabilization/destabilization mechanisms to be proposed. It has also been shown that the dynamic and static stability can be increased by a reduction in particle size and an increase in particle concentration.

Precipitation-lyophilization-homogenization (PLH) for preparation of clarithromycin nanocrystals: influencing factors on physicochemical properties and stability.

PubMed

Morakul, Boontida; Suksiriworapong, Jiraphong; Leanpolchareanchai, Jiraporn; Junyaprasert, Varaporn Buraphacheep

2013-11-30

Nanocrystals is one of effective technologies used to improve solubility and dissolution behavior of poorly soluble drugs. Clarithromycin is classified in BCS class II having low bioavailability due to very low dissolution behavior. The main purpose of this study was to investigate an efficiency of clarithromycin nanocrystals preparation by precipitation-lyophilization-homogenization (PLH) combination method in comparison with high pressure homogenization (HPH) method. The factors influencing particle size reduction and physical stability were assessed. The results showed that the PLH technique provided an effective and rapid reduction of particle size of nanocrystals to 460 ± 10 nm with homogeneity size distribution after only the fifth cycle of homogenization, whereas the same size was attained after 30 cycles by the HPH method. The smallest nanocrystals were achieved by using the combination of poloxamer 407 (2%, w/v) and SLS (0.1%, w/v) as stabilizers. This combination could prevent the particle aggregation over 3-month storage at 4 °C. The results from SEM showed that the clarithromycin nanocrystals were in cubic-shaped similar to its initial particle morphology. The DSC thermogram and X-ray diffraction pattern of nanocrystals were not different from the original drug except for intensity of peaks which indicated the presenting of nanocrystals in the crystalline state and/or partial amorphous form. In addition, the dissolution of the clarithromycin nanocrystals was dramatically increased as compared to the coarse clarithromycin. Copyright © 2013 Elsevier B.V. All rights reserved.

Design of a practical model-observer-based image quality assessment method for CT imaging systems

NASA Astrophysics Data System (ADS)

Tseng, Hsin-Wu; Fan, Jiahua; Cao, Guangzhi; Kupinski, Matthew A.; Sainath, Paavana

2014-03-01

The channelized Hotelling observer (CHO) is a powerful method for quantitative image quality evaluations of CT systems and their image reconstruction algorithms. It has recently been used to validate the dose reduction capability of iterative image-reconstruction algorithms implemented on CT imaging systems. The use of the CHO for routine and frequent system evaluations is desirable both for quality assurance evaluations as well as further system optimizations. The use of channels substantially reduces the amount of data required to achieve accurate estimates of observer performance. However, the number of scans required is still large even with the use of channels. This work explores different data reduction schemes and designs a new approach that requires only a few CT scans of a phantom. For this work, the leave-one-out likelihood (LOOL) method developed by Hoffbeck and Landgrebe is studied as an efficient method of estimating the covariance matrices needed to compute CHO performance. Three different kinds of approaches are included in the study: a conventional CHO estimation technique with a large sample size, a conventional technique with fewer samples, and the new LOOL-based approach with fewer samples. The mean value and standard deviation of area under ROC curve (AUC) is estimated by shuffle method. Both simulation and real data results indicate that an 80% data reduction can be achieved without loss of accuracy. This data reduction makes the proposed approach a practical tool for routine CT system assessment.

High-Performance Cryogenic Designs for OMEGA and the National Ignition Facility

NASA Astrophysics Data System (ADS)

Goncharov, V. N.; Collins, T. J. B.; Marozas, J. A.; Regan, S. P.; Betti, R.; Boehly, T. R.; Campbell, E. M.; Froula, D. H.; Igumenshchev, I. V.; McCrory, R. L.; Myatt, J. F.; Radha, P. B.; Sangster, T. C.; Shvydky, A.

2016-10-01

The main advantage of laser symmetric direct drive (SDD) is a significantly higher coupled drive laser energy to the hot-spot internal energy at stagnation compared to that of laser indirect drive. Because of coupling losses resulting from cross-beam energy transfer (CBET), however, reaching ignition conditions on the NIF with SDD requires designs with excessively large in-flight aspect ratios ( 30). Results of cryogenic implosions performed on OMEGA show that such designs are unstable to short-scale nonuniformity growth during shell implosion. Several CBET reduction strategies have been proposed in the past. This talk will discuss high-performing designs using several CBET-mitigation techniques, including using drive laser beams smaller than the target size and wavelength detuning. Designs that are predicted to reach alpha burning regimes as well as a gain of 10 to 40 at the NIF-scale will be presented. Hydrodynamically scaled OMEGA designs with similar CBET-reduction techniques will also be discussed. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Massive bilateral breast reduction in an 11-year-old girl: 24% ablation of body weight.

PubMed

Fiumara, Linda; Gault, David T; Nel, Mark R; Lucas, Dominique N; Courtauld, Elizabeth

2009-08-01

An 11-year-old girl with massive virginal breast hypertrophy is presented. The breasts had begun to grow rapidly at puberty and had reached an enormous size within a year, to the point of causing physical impairment and respiratory compromise. Routine blood chemistry and endocrine investigation was normal, as was an MRI scan of the pituitary fossa. A bilateral reduction mammaplasty with free nipple grafts was performed, removing 12.5 kg of tissue in all (24% of the total body weight). There was no recurrence at a 2 year follow up, and no requirement for additional surgery. A review of the literature reveals that breast regrowth is less frequent when free nipple grafting is used, and this technique is recommended for these extraordinary cases.

Spacelab user interaction

NASA Technical Reports Server (NTRS)

1975-01-01

The results of the third and final phase of a study undertaken to define means of optimizing the Spacelab experiment data system by interactively manipulating the flow of data were presented. A number of payload applicable interactive techniques and an integrated interaction system for each of two possible payloads are described. These interaction systems have been functionally defined and are accompanied with block diagrams, hardware specifications, software sizing and speed requirements, operational procedures and cost/benefits analysis data for both onboard and ground based system elements. It is shown that accrued benefits are attributable to a reduction in data processing costs obtained by, generally, a considerable reduction in the quantity of data that might otherwise be generated without interaction. One other additional anticipated benefit includes the increased scientific value obtained by the quicker return of all useful data.

An inverter-based capacitive trans-impedance amplifier readout with offset cancellation and temporal noise reduction for IR focal plane array

NASA Astrophysics Data System (ADS)

Chen, Hsin-Han; Hsieh, Chih-Cheng

2013-09-01

This paper presents a readout integrated circuit (ROIC) with inverter-based capacitive trans-impedance amplifier (CTIA) and pseudo-multiple sampling technique for infrared focal plane array (IRFPA). The proposed inverter-based CTIA with a coupling capacitor [1], executing auto-zeroing technique to cancel out the varied offset voltage from process variation, is used to substitute differential amplifier in conventional CTIA. The tunable detector bias is applied from a global external bias before exposure. This scheme not only retains stable detector bias voltage and signal injection efficiency, but also reduces the pixel area as well. Pseudo-multiple sampling technique [2] is adopted to reduce the temporal noise of readout circuit. The noise reduction performance is comparable to the conventional multiple sampling operation without need of longer readout time proportional to the number of samples. A CMOS image sensor chip with 55×65 pixel array has been fabricated in 0.18um CMOS technology. It achieves a 12um×12um pixel size, a frame rate of 72 fps, a power-per-pixel of 0.66uW/pixel, and a readout temporal noise of 1.06mVrms (16 times of pseudo-multiple sampling), respectively.

Improving the quality of reconstructed X-ray CT images of polymer gel dosimeters: zero-scan coupled with adaptive mean filtering.

PubMed

Kakakhel, M B; Jirasek, A; Johnston, H; Kairn, T; Trapp, J V

2017-03-01

This study evaluated the feasibility of combining the 'zero-scan' (ZS) X-ray computed tomography (CT) based polymer gel dosimeter (PGD) readout with adaptive mean (AM) filtering for improving the signal to noise ratio (SNR), and to compare these results with available average scan (AS) X-ray CT readout techniques. NIPAM PGD were manufactured, irradiated with 6 MV photons, CT imaged and processed in Matlab. AM filter for two iterations, with 3 × 3 and 5 × 5 pixels (kernel size), was used in two scenarios (a) the CT images were subjected to AM filtering (pre-processing) and these were further employed to generate AS and ZS gel images, and (b) the AS and ZS images were first reconstructed from the CT images and then AM filtering was carried out (post-processing). SNR was computed in an ROI of 30 × 30 for different pre and post processing cases. Results showed that the ZS technique combined with AM filtering resulted in improved SNR. Using the previously-recommended 25 images for reconstruction the ZS pre-processed protocol can give an increase of 44% and 80% in SNR for 3 × 3 and 5 × 5 kernel sizes respectively. However, post processing using both techniques and filter sizes introduced blur and a reduction in the spatial resolution. Based on this work, it is possible to recommend that the ZS method may be combined with pre-processed AM filtering using appropriate kernel size, to produce a large increase in the SNR of the reconstructed PGD images.

Clinical Outcome Following Radiofrequency Denervation for Refractory Sacroiliac Joint Dysfunction Using the Simplicity III Probe: A 12-Month Retrospective Evaluation.

PubMed

Hegarty, Dominic

2016-01-01

Sacroiliac joint syndrome (SIJ) is diagnosed in 10% to 25% of cases of lower back pain. The response to traditional radiofrequency (RF) denervation of the SIJ has being inconsistent. The Simplicity III RF probe (Neruotherm. Inc.) offers a novel treatment option. To evaluate the long-term clinical outcome (12 months) refractory SIJ syndrome in terms of pain intensity and functional improvement. A 50% reduction in intensity pain intensity (VAS) at 12 months was deemed clinically significant. A 12-month retrospective observational evaluation all of adults treated with RF for refractory SIJ. Chronic pain management center. The medical records of all adults treated with this technique was retrospectively reviewed. The primary outcome was pain intensity scores (VAS) over a 12 months period; Secondary outcomes included Roland-Morris Functional scores (RMF), Brief Pain Inventory (BPI), general health assessment (Sf12), and patient satisfaction scores (GPI), which were recorded pre and post denervation. Pain Intensity improved by 4.7 points compared to pre-treatment representing a 61% reduction in pain at 12 months (n=11, P < 0.001). Significant improvements in (a) RMF (P < 0.01, W2 = 0.63 (large effect size); (b) BPI (P < 0.001, W2 = 0.72 (strong effect size); and (c) Sf12 (P < 0.01) were noted. Overall patients were satisfied with the outcome (GPI = 77.7%). The retrospective in nature of the study and the small sample size are limitations. As it was our policy to monitor the progress of the individuals since the introduction of this technique a reliable method of recording the baseline and outcome variables at each point of contact was in place. Access to a complete set of variables in all individuals over a 12-month period was therefore possible, which we feel contributes to the quality of the dataset. By creating a consistent radiofrequency lesion between the sacral foramen and the SIJ will reliably capture the innervation to the SIJ with significant long-term clinical improvement. This technique should be considered earlier in the treatment algorithm of individuals suffering from SIJ symptoms.

Drag and Side Force Reduction for Cyclicsts in Echelon Formation

NASA Astrophysics Data System (ADS)

Nedyalkov, Ivaylo; Cunningham, Alec; Lovell, Adam

2017-11-01

When riding directly behind another cyclist (drafting), a rider can use up to 30% less energy. This technique is often used during competitions, yet drafting in the presence of a cross wind has not been studied extensively. To investigate the effect of side-wind on drafting, 1:11 scale models of two different cyclists were rapid-prototyped and tested in a wind tunnel. The drag and side forces were measured in formations of up to 4 models. The results suggest that there is a significant decrease in both drag and side force when a cyclist is riding in another cyclist's wake. Positioning with no off-stream-wise offset result in the largest reduction of forces. When riding in a group of four cyclists, the second and third cyclist experience the largest force reduction. The size of the leading cyclist affects the reduction of forces, particularly when the leading cyclist is smaller. The results are dependent on the Reynolds number, but appear to be independent at higher Reynolds numbers. Initial full scale tests were conducted at the UNH Flow Physics Facility.

Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

PubMed

Manga, Mohamed S; York, David W

2017-09-12

Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

APPLICATION OF VARIOUS POLYMERS AND POLYMERS BASED TECHNIQUES USED TO IMPROVE SOLUBILITY OF POORLY WATER SOLUBLE DRUGS: A REVIEW.

PubMed

Muhammad Sarfraz, Rai; Bashir, Sajid; Mahmood, Asif; Ahsan, Haseeb; Riaz, Humayun; Raza, Hina; Rashid, Zermina; Atif Raza, Syed; Asad Abrar, Muhammad; Abbas, Khawar; Yasmeen, Tahira

2017-03-01

Solubility is concerned with solute and solvent to form a homogenous mixture. If solubility of a drug is low, then usually it is difficult to achieve desired therapeutic level of drug. Most of the newly developed entities have solubility problems and encounter difficulty in dissolution. Basic aim of solubility enhancement is to achieve desired therapeutic'level of drug to produce required pharmacological response. Different techniques are being used to enhance the solubility of water insoluble drugs. These techniques include particle size reduction, spray drying, kneading method, solvent evaporation method, salt formation, microemulsions, co-solven- cy, hydrosols, prodrug approach, supercritical fluid process, hydrogel micro particles etc. Selection of solubility improving method depends on drug properties, site of absorption, and required dosage form characteristics. Variety of polymers are also used to enhance solubility of these drugs like polyethylene glycol 300, polyvinyl pyrrolidone, chitosan, β-cyclodextrins etc.

Techniques for detecting effects of urban and rural land-use practices on stream-water chemistry in selected watersheds in Texas, Minnesota,and Illinois

USGS Publications Warehouse

Walker, J.F.

1993-01-01

Selected statistical techniques were applied to three urban watersheds in Texas and Minnesota and three rural watersheds in Illinois. For the urban watersheds, single- and paired-site data-collection strategies were considered. The paired-site strategy was much more effective than the singlesite strategy for detecting changes. Analysis of storm load regression residuals demonstrated the potential utility of regressions for variability reduction. For the rural watersheds, none of the selected techniques were effective at identifying changes, primarily due to a small degree of management-practice implementation, potential errors introduced through the estimation of storm load, and small sample sizes. A Monte Carlo sensitivity analysis was used to determine the percent change in water chemistry that could be detected for each watershed. In most instances, the use of regressions improved the ability to detect changes.

Simultaneous fabrication of very high aspect ratio positive nano- to milliscale structures.

PubMed

Chen, Long Qing; Chan-Park, Mary B; Zhang, Qing; Chen, Peng; Li, Chang Ming; Li, Sai

2009-05-01

A simple and inexpensive technique for the simultaneous fabrication of positive (i.e., protruding), very high aspect (>10) ratio nanostructures together with micro- or millistructures is developed. The method involves using residual patterns of thin-film over-etching (RPTO) to produce sub-micro-/nanoscale features. The residual thin-film nanopattern is used as an etching mask for Si deep reactive ion etching. The etched Si structures are further reduced in size by Si thermal oxidation to produce amorphous SiO(2), which is subsequently etched away by HF. Two arrays of positive Si nanowalls are demonstrated with this combined RPTO-SiO(2)-HF technique. One array has a feature size of 150 nm and an aspect ratio of 26.7 and another has a feature size of 50 nm and an aspect ratio of 15. No other parallel reduction technique can achieve such a very high aspect ratio for 50-nm-wide nanowalls. As a demonstration of the technique to simultaneously achieve nano- and milliscale features, a simple Si nanofluidic master mold with positive features with dimensions varying continuously from 1 mm to 200 nm and a highest aspect ratio of 6.75 is fabricated; the narrow 200-nm section is 4.5 mm long. This Si master mold is then used as a mold for UV embossing. The embossed open channels are then closed by a cover with glue bonding. A high aspect ratio is necessary to produce unblocked closed channels after the cover bonding process of the nanofluidic chip. The combined method of RPTO, Si thermal oxidation, and HF etching can be used to make complex nanofluidic systems and nano-/micro-/millistructures for diverse applications.

Regression Verification Using Impact Summaries

NASA Technical Reports Server (NTRS)

Backes, John; Person, Suzette J.; Rungta, Neha; Thachuk, Oksana

2013-01-01

Regression verification techniques are used to prove equivalence of syntactically similar programs. Checking equivalence of large programs, however, can be computationally expensive. Existing regression verification techniques rely on abstraction and decomposition techniques to reduce the computational effort of checking equivalence of the entire program. These techniques are sound but not complete. In this work, we propose a novel approach to improve scalability of regression verification by classifying the program behaviors generated during symbolic execution as either impacted or unimpacted. Our technique uses a combination of static analysis and symbolic execution to generate summaries of impacted program behaviors. The impact summaries are then checked for equivalence using an o-the-shelf decision procedure. We prove that our approach is both sound and complete for sequential programs, with respect to the depth bound of symbolic execution. Our evaluation on a set of sequential C artifacts shows that reducing the size of the summaries can help reduce the cost of software equivalence checking. Various reduction, abstraction, and compositional techniques have been developed to help scale software verification techniques to industrial-sized systems. Although such techniques have greatly increased the size and complexity of systems that can be checked, analysis of large software systems remains costly. Regression analysis techniques, e.g., regression testing [16], regression model checking [22], and regression verification [19], restrict the scope of the analysis by leveraging the differences between program versions. These techniques are based on the idea that if code is checked early in development, then subsequent versions can be checked against a prior (checked) version, leveraging the results of the previous analysis to reduce analysis cost of the current version. Regression verification addresses the problem of proving equivalence of closely related program versions [19]. These techniques compare two programs with a large degree of syntactic similarity to prove that portions of one program version are equivalent to the other. Regression verification can be used for guaranteeing backward compatibility, and for showing behavioral equivalence in programs with syntactic differences, e.g., when a program is refactored to improve its performance, maintainability, or readability. Existing regression verification techniques leverage similarities between program versions by using abstraction and decomposition techniques to improve scalability of the analysis [10, 12, 19]. The abstractions and decomposition in the these techniques, e.g., summaries of unchanged code [12] or semantically equivalent methods [19], compute an over-approximation of the program behaviors. The equivalence checking results of these techniques are sound but not complete-they may characterize programs as not functionally equivalent when, in fact, they are equivalent. In this work we describe a novel approach that leverages the impact of the differences between two programs for scaling regression verification. We partition program behaviors of each version into (a) behaviors impacted by the changes and (b) behaviors not impacted (unimpacted) by the changes. Only the impacted program behaviors are used during equivalence checking. We then prove that checking equivalence of the impacted program behaviors is equivalent to checking equivalence of all program behaviors for a given depth bound. In this work we use symbolic execution to generate the program behaviors and leverage control- and data-dependence information to facilitate the partitioning of program behaviors. The impacted program behaviors are termed as impact summaries. The dependence analyses that facilitate the generation of the impact summaries, we believe, could be used in conjunction with other abstraction and decomposition based approaches, [10, 12], as a complementary reduction technique. An evaluation of our regression verification technique shows that our approach is capable of leveraging similarities between program versions to reduce the size of the queries and the time required to check for logical equivalence. The main contributions of this work are: - A regression verification technique to generate impact summaries that can be checked for functional equivalence using an off-the-shelf decision procedure. - A proof that our approach is sound and complete with respect to the depth bound of symbolic execution. - An implementation of our technique using the LLVMcompiler infrastructure, the klee Symbolic Virtual Machine [4], and a variety of Satisfiability Modulo Theory (SMT) solvers, e.g., STP [7] and Z3 [6]. - An empirical evaluation on a set of C artifacts which shows that the use of impact summaries can reduce the cost of regression verification.

Quantifying Spot Size Reduction of a 1.8 kA Electron Beam for Flash Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burris-Mog, Trevor John; Moir, David C.

The spot size of Axis-I at the Dual Axis Radiographic Hydrodynamic Test facility was reduced by 15.5% by including a small diameter drift tube that acts to aperture the outer diameter of the electron beam. Comparing the measured values to both analytic calculations and results from a particle-in-cell model shows that one-third to one-half of the spot size reduction is due to a drop in beam emittance. We infer that one-half to two-thirds of the spot-size reduction is due to a reduction in beam-target interactions. Sources of emittance growth and the scaling of the final focal spot size with emittancemore » and solenoid aberrations are also presented.« less

Quantifying Spot Size Reduction of a 1.8 kA Electron Beam for Flash Radiography

DOE PAGES

Burris-Mog, Trevor John; Moir, David C.

2018-03-14

The spot size of Axis-I at the Dual Axis Radiographic Hydrodynamic Test facility was reduced by 15.5% by including a small diameter drift tube that acts to aperture the outer diameter of the electron beam. Comparing the measured values to both analytic calculations and results from a particle-in-cell model shows that one-third to one-half of the spot size reduction is due to a drop in beam emittance. We infer that one-half to two-thirds of the spot-size reduction is due to a reduction in beam-target interactions. Sources of emittance growth and the scaling of the final focal spot size with emittancemore » and solenoid aberrations are also presented.« less

Universal data compression

NASA Astrophysics Data System (ADS)

Lindsay, R. A.; Cox, B. V.

Universal and adaptive data compression techniques have the capability to globally compress all types of data without loss of information but have the disadvantage of complexity and computation speed. Advances in hardware speed and the reduction of computational costs have made universal data compression feasible. Implementations of the Adaptive Huffman and Lempel-Ziv compression algorithms are evaluated for performance. Compression ratios versus run times for different size data files are graphically presented and discussed in the paper. Required adjustments needed for optimum performance of the algorithms relative to theoretical achievable limits will be outlined.

Early Elementary Class-Size Reduction: A Neo-Institutional Analysis of the Social, Political, and Economic Influences on State-Level Policymaking.

ERIC Educational Resources Information Center

Mitchell, Ross E.

This paper examines the social, political, and economic factors that influenced the adoption and diffusion of early-elementary school class-size-reduction policies at the state level. It applies a neo-institutional framework to explain the rapid spread of class-size reduction policies throughout many state legislatures and boards of education. It…

Additive manufacturing of magnetic shielding and ultra-high vacuum flange for cold atom sensors.

PubMed

Vovrosh, Jamie; Voulazeris, Georgios; Petrov, Plamen G; Zou, Ji; Gaber, Youssef; Benn, Laura; Woolger, David; Attallah, Moataz M; Boyer, Vincent; Bongs, Kai; Holynski, Michael

2018-01-31

Recent advances in the understanding and control of quantum technologies, such as those based on cold atoms, have resulted in devices with extraordinary metrological performance. To realise this potential outside of a lab environment the size, weight and power consumption need to be reduced. Here we demonstrate the use of laser powder bed fusion, an additive manufacturing technique, as a production technique relevant to the manufacture of quantum sensors. As a demonstration we have constructed two key components using additive manufacturing, namely magnetic shielding and vacuum chambers. The initial prototypes for magnetic shields show shielding factors within a factor of 3 of conventional approaches. The vacuum demonstrator device shows that 3D-printed titanium structures are suitable for use as vacuum chambers, with the test system reaching base pressures of 5 ± 0.5 × 10 -10 mbar. These demonstrations show considerable promise for the use of additive manufacturing for cold atom based quantum technologies, in future enabling improved integrated structures, allowing for the reduction in size, weight and assembly complexity.

Non-invasive brain stimulation in Parkinson's disease: Exploiting crossroads of cognition and mood.

PubMed

Dinkelbach, Lars; Brambilla, Michela; Manenti, Rosa; Brem, Anna-Katharine

2017-04-01

Cognitive impairments and depression are common non-motor manifestations in Parkinson's disease (PD). Recent evidence suggests that both partially arise via the same frontostriatal network, opening the opportunity for concomitant treatment with non-invasive brain stimulation (NIBS) techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). In this systematic review, we evaluate the effects of NIBS on cognition and/or mood in 19 placebo-controlled studies involving 561 PD patients. Outcomes depended on the area stimulated and the technique used. rTMS over the dorsolateral-prefrontal cortex (DLPFC) resulted in significant reductions in scores of depressive symptoms with moderate to large effect sizes along with increased performance in several tests of cognitive functions. tDCS over the DLPFC improved performance in several cognitive measures, including executive functions with large effect sizes. Additional effects of tDCS on mood were not detectable; however, only non-depressed patients were assessed. Further confirmatory research is needed to clarify the contribution that NIBS could make in the care of PD patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-resolution non-destructive three-dimensional imaging of integrated circuits.

PubMed

Holler, Mirko; Guizar-Sicairos, Manuel; Tsai, Esther H R; Dinapoli, Roberto; Müller, Elisabeth; Bunk, Oliver; Raabe, Jörg; Aeppli, Gabriel

2017-03-15

Modern nanoelectronics has advanced to a point at which it is impossible to image entire devices and their interconnections non-destructively because of their small feature sizes and the complex three-dimensional structures resulting from their integration on a chip. This metrology gap implies a lack of direct feedback between design and manufacturing processes, and hampers quality control during production, shipment and use. Here we demonstrate that X-ray ptychography-a high-resolution coherent diffractive imaging technique-can create three-dimensional images of integrated circuits of known and unknown designs with a lateral resolution in all directions down to 14.6 nanometres. We obtained detailed device geometries and corresponding elemental maps, and show how the devices are integrated with each other to form the chip. Our experiments represent a major advance in chip inspection and reverse engineering over the traditional destructive electron microscopy and ion milling techniques. Foreseeable developments in X-ray sources, optics and detectors, as well as adoption of an instrument geometry optimized for planar rather than cylindrical samples, could lead to a thousand-fold increase in efficiency, with concomitant reductions in scan times and voxel sizes.

Software Support for Transiently Powered Computers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Der Woude, Joel Matthew

With the continued reduction in size and cost of computing, power becomes an increasingly heavy burden on system designers for embedded applications. While energy harvesting techniques are an increasingly desirable solution for many deeply embedded applications where size and lifetime are a priority, previous work has shown that energy harvesting provides insufficient power for long running computation. We present Ratchet, which to the authors knowledge is the first automatic, software-only checkpointing system for energy harvesting platforms. We show that Ratchet provides a means to extend computation across power cycles, consistent with those experienced by energy harvesting devices. We demonstrate themore » correctness of our system under frequent failures and show that it has an average overhead of 58.9% across a suite of benchmarks representative for embedded applications.« less

Modelled Cost-Effectiveness of a Package Size Cap and a Kilojoule Reduction Intervention to Reduce Energy Intake from Sugar-Sweetened Beverages in Australia.

PubMed

Crino, Michelle; Herrera, Ana Maria Mantilla; Ananthapavan, Jaithri; Wu, Jason H Y; Neal, Bruce; Lee, Yong Yi; Zheng, Miaobing; Lal, Anita; Sacks, Gary

2017-09-06

Interventions targeting portion size and energy density of food and beverage products have been identified as a promising approach for obesity prevention. This study modelled the potential cost-effectiveness of: a package size cap on single-serve sugar sweetened beverages (SSBs) >375 mL ( package size cap ), and product reformulation to reduce energy content of packaged SSBs ( energy reduction ). The cost-effectiveness of each intervention was modelled for the 2010 Australia population using a multi-state life table Markov model with a lifetime time horizon. Long-term health outcomes were modelled from calculated changes in body mass index to their impact on Health-Adjusted Life Years (HALYs). Intervention costs were estimated from a limited societal perspective. Cost and health outcomes were discounted at 3%. Total intervention costs estimated in AUD 2010 were AUD 210 million. Both interventions resulted in reduced mean body weight ( package size cap : 0.12 kg; energy reduction : 0.23 kg); and HALYs gained ( package size cap : 73,883; energy reduction : 144,621). Cost offsets were estimated at AUD 750.8 million ( package size cap ) and AUD 1.4 billion ( energy reduction ). Cost-effectiveness analyses showed that both interventions were "dominant", and likely to result in long term cost savings and health benefits. A package size cap and kJ reduction of SSBs are likely to offer excellent "value for money" as obesity prevention measures in Australia.

Modelled Cost-Effectiveness of a Package Size Cap and a Kilojoule Reduction Intervention to Reduce Energy Intake from Sugar-Sweetened Beverages in Australia

PubMed Central

Mantilla Herrera, Ana Maria; Neal, Bruce; Zheng, Miaobing; Lal, Anita; Sacks, Gary

2017-01-01

Interventions targeting portion size and energy density of food and beverage products have been identified as a promising approach for obesity prevention. This study modelled the potential cost-effectiveness of: a package size cap on single-serve sugar sweetened beverages (SSBs) >375 mL (package size cap), and product reformulation to reduce energy content of packaged SSBs (energy reduction). The cost-effectiveness of each intervention was modelled for the 2010 Australia population using a multi-state life table Markov model with a lifetime time horizon. Long-term health outcomes were modelled from calculated changes in body mass index to their impact on Health-Adjusted Life Years (HALYs). Intervention costs were estimated from a limited societal perspective. Cost and health outcomes were discounted at 3%. Total intervention costs estimated in AUD 2010 were AUD 210 million. Both interventions resulted in reduced mean body weight (package size cap: 0.12 kg; energy reduction: 0.23 kg); and HALYs gained (package size cap: 73,883; energy reduction: 144,621). Cost offsets were estimated at AUD 750.8 million (package size cap) and AUD 1.4 billion (energy reduction). Cost-effectiveness analyses showed that both interventions were “dominant”, and likely to result in long term cost savings and health benefits. A package size cap and kJ reduction of SSBs are likely to offer excellent “value for money” as obesity prevention measures in Australia. PMID:28878175

Deformation behavior of laser welds in high temperature oxidation resistant Fe-Cr-Al alloys for fuel cladding applications

NASA Astrophysics Data System (ADS)

Field, Kevin G.; Gussev, Maxim N.; Yamamoto, Yukinori; Snead, Lance L.

2014-11-01

Ferritic-structured Fe-Cr-Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

Attention management as a treatment for chronic pain.

PubMed

Elomaa, Minna M; de C Williams, Amanda C; Kalso, Eija A

2009-11-01

Attention management is often included in cognitive-behavioural treatments (CBT). The aim of this study was to evaluate the effects of attention management strategies in the treatment for chronic pain. The present pilot study consisted of six weekly 90-min treatment sessions and was based on a CBT attention management manual describing techniques such as attention diversion, imagery and mindfulness exercises. The intended outcomes were reduction in pain-related anxiety and hypervigilance to pain and decrease in pain impact of everyday life, measured by self-report. Information was collected at baseline, pre-treatment, post-treatment, and at 3 and 6 months follow-up. The results at the end of treatment, and at 3-month follow-up, show significant reductions in pain-related anxiety, hypervigilance and interference of pain (effect sizes 0.40-0.90). Reduction in pain-related interference and anxiety remained at the 6-month follow-up. The results indicate that attention control skills can be a useful method to reduce anxiety in the short term. Clinical implications of the results are discussed.

Redox behavior of uranium at the nanoporous aluminum oxide-water interface: implications for uranium remediation.

PubMed

Jung, Hun Bok; Boyanov, Maxim I; Konishi, Hiromi; Sun, Yubing; Mishra, Bhoopesh; Kemner, Kenneth M; Roden, Eric E; Xu, Huifang

2012-07-03

Sorption-desorption experiments show that the majority (ca. 80-90%) of U(VI) presorbed to mesoporous and nanoporous alumina could not be released by extended (2 week) extraction with 50 mM NaHCO(3) in contrast with non-nanoporous α alumina. The extent of reduction of U(VI) presorbed to aluminum oxides was semiquantitatively estimated by comparing the percentages of uranium desorbed by anoxic sodium bicarbonate between AH(2)DS-reacted and unreacted control samples. X-ray absorption spectroscopy confirmed that U(VI) presorbed to non-nanoporous alumina was rapidly and completely reduced to nanoparticulate uraninite by AH(2)DS, whereas reduction of U(VI) presorbed to nanoporous alumina was slow and incomplete (<5% reduction after 1 week). The observed nanopore size-dependent redox behavior of U has important implications in developing efficient remediation techniques for the subsurface uranium contamination because the efficiency of in situ bioremediation depends on how effectively and rapidly U(VI) bound to sediment or soil can be converted to an immobile phase.

Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst

PubMed Central

Dutta, Indrajit; Carpenter, Michael K; Balogh, Michael P; Ziegelbauer, Joseph M; Moylan, Thomas E; Atwan, Mohammed H; Irish, Nicholas P

2013-01-01

A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multi-step synthetic procedure. Material produced at each step was characterized using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) mapping, x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and cyclic voltammetry (CV), and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode (TF-RDE) technique. The initial synthetic step, a co-reduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. TEM shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12–25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete coreshell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a “Swiss cheese” type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report. PMID:23807900

The Effect of Atrial Fibrillation Ablation Techniques on P Wave Duration and P Wave Dispersion.

PubMed

Furniss, Guy O; Panagopoulos, Dimitrios; Kanoun, Sadeek; Davies, Edward J; Tomlinson, David R; Haywood, Guy A

2018-02-14

A reduction in surface electrocardiogram (ECG) P wave duration and dispersion is associated with improved outcomes in atrial fibrillation ablation. We investigated the effects of different ablation strategies on P wave duration and dispersion, hypothesising that extensive left atrial (LA) ablation with left atrial posterior wall isolation would give a greater reduction in P wave duration than more limited ablation techniques. A retrospective analysis of ECGs from patients who have undergone atrial fibrillation (AF) ablation was performed and pre-procedural sinus rhythm ECGs were compared with the post procedure ECGs. Maximal P wave duration was measured in leads I or II, minimum P wave duration in any lead and values were calculated for P wave duration and dispersion. Left atrial dimensions and medications at the time of ECG were documented. Ablation strategies compared were; pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) and the persistent AF (PsAF) ablation strategies of pulmonary vein isolation plus additional linear lesions (Lines), left atrial posterior wall isolation via catheter (PWI) and left atrial posterior wall isolation via staged surgical and catheter ablation (Hybrid). Sixty-nine patients' ECGs were analysed: 19 PVI, 21 Lines, 14 PWI, 15 Hybrid. Little correlation was seen between pre-procedure left atrial size and P wave duration (r=0.24) but LA size and P wave duration was larger in PsAF patients. A significant difference was seen in P wave reduction driven by Hybrid AF ablation (p<0.005) and Lines (<0.02). There was no difference amongst P wave dispersion between groups but the largest reduction was seen in the Hybrid ablation group. P wave duration increased with duration of continuous atrial fibrillation. Hybrid AF ablation significantly reduced P wave duration and dispersion compared to other ablation strategies including posterior wall isolation via catheter despite this being the same lesion set. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Safety screw fixation technique in a case of coracoid base fracture with acromioclavicular dislocation and coracoid base cross-sectional size data from a computed axial tomography study.

PubMed

Kawasaki, Yoshiteru; Hirano, Tetsuya; Miyatake, Katsutoshi; Fujii, Koji; Takeda, Yoshitsugu

2014-07-01

Coracoid base fracture accompanied by acromioclavicular joint dislocation with intact coracoclavicular ligaments is a rare injury. Generally, an open reduction with screw fixation is the first treatment choice, as it protects the important structures around the coracoid process. This report presents a new technique of screw fixation for coracoid base fracture and provides anatomic information on cross-sectional size of the coracoid base obtained by computed tomography (CT). An axial image of the coracoid base was visualized over the neck of the scapula, and a guidewire was inserted into this circle under fluoroscopic guidance. The wire was inserted easily into the neck of scapula across the coracoid base fracture with imaging in only 1 plane. In addition, 25 measurements of the coracoid base were made in 25 subjects on axial CT images. Average length of the long and short axes at the thinnest part of the coracoid base was 13.9 ± 2.0 mm (range 10.6-17.0) and 10.5 ± 2.2 mm (6.6-15.1), respectively. This new screw fixation technique and measurement data on the coracoid base may be beneficial for safety screw fixation of coracoid base fracture.

Analyzing coastal environments by means of functional data analysis

NASA Astrophysics Data System (ADS)

Sierra, Carlos; Flor-Blanco, Germán; Ordoñez, Celestino; Flor, Germán; Gallego, José R.

2017-07-01

Here we used Functional Data Analysis (FDA) to examine particle-size distributions (PSDs) in a beach/shallow marine sedimentary environment in Gijón Bay (NW Spain). The work involved both Functional Principal Components Analysis (FPCA) and Functional Cluster Analysis (FCA). The grainsize of the sand samples was characterized by means of laser dispersion spectroscopy. Within this framework, FPCA was used as a dimension reduction technique to explore and uncover patterns in grain-size frequency curves. This procedure proved useful to describe variability in the structure of the data set. Moreover, an alternative approach, FCA, was applied to identify clusters and to interpret their spatial distribution. Results obtained with this latter technique were compared with those obtained by means of two vector approaches that combine PCA with CA (Cluster Analysis). The first method, the point density function (PDF), was employed after adapting a log-normal distribution to each PSD and resuming each of the density functions by its mean, sorting, skewness and kurtosis. The second applied a centered-log-ratio (clr) to the original data. PCA was then applied to the transformed data, and finally CA to the retained principal component scores. The study revealed functional data analysis, specifically FPCA and FCA, as a suitable alternative with considerable advantages over traditional vector analysis techniques in sedimentary geology studies.

Remediation of metal-contaminated urban soil using flotation technique.

PubMed

Dermont, G; Bergeron, M; Richer-Laflèche, M; Mercier, G

2010-02-01

A soil washing process using froth flotation technique was evaluated for the removal of arsenic, cadmium, copper, lead, and zinc from a highly contaminated urban soil (brownfield) after crushing of the particle-size fractions >250microm. The metal contaminants were in particulate forms and distributed in all the particle-size fractions. The particle-by-particle study with SEM-EDS showed that Zn was mainly present as sphalerite (ZnS), whereas Cu and Pb were mainly speciated as various oxide/carbonate compounds. The influence of surfactant collector type (non-ionic and anionic), collector dosage, pulp pH, a chemical activation step (sulfidization), particle size, and process time on metal removal efficiency and flotation selectivity was studied. Satisfactory results in metal recovery (42-52%), flotation selectivity (concentration factor>2.5), and volume reduction (>80%) were obtained with anionic collector (potassium amyl xanthate). The transportation mechanisms involved in the separation process (i.e., the true flotation and the mechanical entrainment) were evaluated by the pulp chemistry, the metal speciation, the metal distribution in the particle-size fractions, and the separation selectivity indices of Zn/Ca and Zn/Fe. The investigations showed that a great proportion of metal-containing particles were recovered in the froth layer by entrainment mechanism rather than by true flotation process. The non-selective entrainment mechanism of the fine particles (<20 microm) caused a flotation selectivity drop, especially with a long flotation time (>5 min) and when a high collector dose is used. The intermediate particle-size fraction (20-125 microm) showed the best flotation selectivity. Copyright 2009 Elsevier B.V. All rights reserved.

Direct Wafer Bonding and Its Application to Waveguide Optical Isolators

PubMed Central

Mizumoto, Tetsuya; Shoji, Yuya; Takei, Ryohei

2012-01-01

This paper reviews the direct bonding technique focusing on the waveguide optical isolator application. A surface activated direct bonding technique is a powerful tool to realize a tight contact between dissimilar materials. This technique has the potential advantage that dissimilar materials are bonded at low temperature, which enables one to avoid the issue associated with the difference in thermal expansion. Using this technique, a magneto-optic garnet is successfully bonded on silicon, III-V compound semiconductors and LiNbO3. As an application of this technique, waveguide optical isolators are investigated including an interferometric waveguide optical isolator and a semileaky waveguide optical isolator. The interferometric waveguide optical isolator that uses nonreciprocal phase shift is applicable to a variety of waveguide platforms. The low refractive index of buried oxide layer in a silicon-on-insulator (SOI) waveguide enhances the magneto-optic phase shift, which contributes to the size reduction of the isolator. A semileaky waveguide optical isolator has the advantage of large fabrication-tolerance as well as a wide operation wavelength range. PMID:28817020

Optimal neighborhood indexing for protein similarity search.

PubMed

Peterlongo, Pierre; Noé, Laurent; Lavenier, Dominique; Nguyen, Van Hoa; Kucherov, Gregory; Giraud, Mathieu

2008-12-16

Similarity inference, one of the main bioinformatics tasks, has to face an exponential growth of the biological data. A classical approach used to cope with this data flow involves heuristics with large seed indexes. In order to speed up this technique, the index can be enhanced by storing additional information to limit the number of random memory accesses. However, this improvement leads to a larger index that may become a bottleneck. In the case of protein similarity search, we propose to decrease the index size by reducing the amino acid alphabet. The paper presents two main contributions. First, we show that an optimal neighborhood indexing combining an alphabet reduction and a longer neighborhood leads to a reduction of 35% of memory involved into the process, without sacrificing the quality of results nor the computational time. Second, our approach led us to develop a new kind of substitution score matrices and their associated e-value parameters. In contrast to usual matrices, these matrices are rectangular since they compare amino acid groups from different alphabets. We describe the method used for computing those matrices and we provide some typical examples that can be used in such comparisons. Supplementary data can be found on the website http://bioinfo.lifl.fr/reblosum. We propose a practical index size reduction of the neighborhood data, that does not negatively affect the performance of large-scale search in protein sequences. Such an index can be used in any study involving large protein data. Moreover, rectangular substitution score matrices and their associated statistical parameters can have applications in any study involving an alphabet reduction.

Optimal neighborhood indexing for protein similarity search

PubMed Central

Peterlongo, Pierre; Noé, Laurent; Lavenier, Dominique; Nguyen, Van Hoa; Kucherov, Gregory; Giraud, Mathieu

2008-01-01

Background Similarity inference, one of the main bioinformatics tasks, has to face an exponential growth of the biological data. A classical approach used to cope with this data flow involves heuristics with large seed indexes. In order to speed up this technique, the index can be enhanced by storing additional information to limit the number of random memory accesses. However, this improvement leads to a larger index that may become a bottleneck. In the case of protein similarity search, we propose to decrease the index size by reducing the amino acid alphabet. Results The paper presents two main contributions. First, we show that an optimal neighborhood indexing combining an alphabet reduction and a longer neighborhood leads to a reduction of 35% of memory involved into the process, without sacrificing the quality of results nor the computational time. Second, our approach led us to develop a new kind of substitution score matrices and their associated e-value parameters. In contrast to usual matrices, these matrices are rectangular since they compare amino acid groups from different alphabets. We describe the method used for computing those matrices and we provide some typical examples that can be used in such comparisons. Supplementary data can be found on the website . Conclusion We propose a practical index size reduction of the neighborhood data, that does not negatively affect the performance of large-scale search in protein sequences. Such an index can be used in any study involving large protein data. Moreover, rectangular substitution score matrices and their associated statistical parameters can have applications in any study involving an alphabet reduction. PMID:19087280

Nickel-doped cobalt ferrite nanoparticles: efficient catalysts for the reduction of nitroaromatic compounds and photo-oxidative degradation of toxic dyes.

PubMed

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-07-21

This study deals with the exploration of NixCo₁-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co₀.₄Ni₀.₆Fe₂O₄ (154.02 m(2) g(-1)). Co₀.₄Ni₀.₆Fe₂O₄ showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe₂O₄ was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH₄ on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni(2+) in to the cobalt ferrite lattice due to octahedral site preference of Ni(2+). Almost 99% degradation was achieved in 20 min using NiFe₂O₄ nanoparticles as catalyst.

Rocket launcher: A novel reduction technique for posterior hip dislocations and review of current literature.

PubMed

Dan, Michael; Phillips, Alfred; Simonian, Marcus; Flannagan, Scott

2015-06-01

We provide a review of literature on reduction techniques for posterior hip dislocations and present our experience with a novel technique for the reduction of acute posterior hip dislocations in the ED, 'the rocket launcher' technique. We present our results with six patients with prosthetic posterior hip dislocation treated in our rural ED. We recorded patient demographics. The technique involves placing the patient's knee over the shoulder, and holding the lower leg like a 'Rocket Launcher' allow the physician's shoulder to work as a fulcrum, in an ergonomically friendly manner for the reducer. We used Fisher's t-test for cohort analysis between reduction techniques. Of our patients, the mean age was 74 years (range 66 to 85 years). We had a 83% success rate. The one patient who the 'rocket launcher' failed in, was a hemi-arthroplasty patient who also failed all other closed techniques and needed open reduction. When compared with Allis (62% success rate), Whistler (60% success rate) and Captain Morgan (92% success rate) techniques, there was no statistically significant difference in the successfulness of the reduction techniques. There were no neurovascular or periprosthetic complications. We have described a reduction technique for posterior hip dislocations. Placing the patient's knee over the shoulder, and holding the lower leg like a 'Rocket Launcher' allow the physician's shoulder to work as a fulcrum, thus mechanically and ergonomically superior to standard techniques. © 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Size-induced changes of structural and ferromagnetic properties in La1-xSrxMnO3 nanoparticles

NASA Astrophysics Data System (ADS)

Hintze, Cornelia E.; Fuchs, Dirk; Merz, Michael; Amari, Houari; Kübel, Christian; Huang, Meng-Jie; Powell, Annie; v. Löhneysen, Hilbert

2017-06-01

La1-xSrxMnO3 nanocrystals were grown using a microemulsion approach with different water-to-surfactant ratios Rw resulting in diameters between 20 and 40 nm. The variation of Rw entails a variation in the Sr concentrations between x = 0.35 and 0.50. This technique allows the controlled growth of structurally well-defined nanoparticles using the same calcination conditions. With decreasing particle size, the unit-cell volume increases together with the Mn-O bond length, while the Mn-O-Mn bond angle was found to decrease. The size-dependent change of structural properties is possibly related to surface effects or disorder. With the decrease in particle size, the ferromagnetic ordering temperature TC decreases significantly by up to 20%. The reduction of TC can be well understood with respect to the structural changes: the increase of Mn-O bond length and the decrease of Mn-O-Mn bond angle weaken the double-exchange coupling and hence reduce T C . In addition the intrinsic finite-size effect reduces T C . The observed size-induced change of magnetic properties may allow for a controlled manipulation of magnetism in La1-xSrxMnO3 nanoparticles by varying the particle size.

[The Postero-Lateral Approach--An Alternative to Closed Anterior-Posterior Screw Fixation of a Dislocated Postero-Lateral Fragment of the Distal Tibia in Complex Ankle Fractures].

PubMed

von Rüden, C; Hackl, S; Woltmann, A; Friederichs, J; Bühren, V; Hierholzer, C

2015-06-01

The dislocated posterolateral fragment of the distal tibia is considered as a key fragment for the successful reduction of comminuted ankle fractures. The reduction of this fragment can either be achieved indirectly by joint reduction using the technique of closed anterior-posterior screw fixation, or directly using the open posterolateral approach followed by plate fixation. The aim of this study was to compare the outcome after stabilization of the dislocated posterolateral tibia fragment using either closed reduction and screw fixation, or open reduction and plate fixation via the posterolateral approach in complex ankle fractures. In a prospective study between 01/2010 and 12/2012, all mono-injured patients with closed ankle fractures and dislocated posterolateral tibia fragments were assessed 12 months after osteosynthesis. Parameters included: size of the posterolateral tibia fragment relative to the tibial joint surface (CT scan, in %) as an indicator of injury severity, unreduced area of tibial joint surface postoperatively, treatment outcome assessed by using the "Ankle Fracture Scoring System" (AFSS), as well as epidemiological data and duration of the initial hospital treatment. In 11 patients (10 female, 1 male; age 51.6 ± 2.6 years [mean ± SEM], size of tibia fragment 42.1 ± 2.5 %) the fragment fixation was performed using a posterolateral approach. Impaired postoperative wound healing occurred in 2 patients of this group. In the comparison group, 12 patients were treated using the technique of closed anterior-posterior screw fixation (10 female, 2 male; age 59.5 ± 6.7 years, size of tibia fragment 45.9 ± 1.5 %). One patient of this group suffered an incomplete lesion of the superficial peroneal nerve. Radiological evaluation of the joint surface using CT scan imaging demonstrated significantly less dislocation of the tibial joint surface following the open posterolateral approach (0.60 ± 0.20 mm) compared to the closed anterior-posterior screw fixation (1.03 ± 0.08 mm; p < 0.05). Assessment of the treatment outcome using the AFSS demonstrated a significantly higher score of 97.4 ± 6.4 in the group with a posterolateral approach compared to a score of 74.4 ± 12.1 (p < 0.05) in the group with an anterior-posterior screw fixation. In comparison to the anterior-posterior screw fixation, open reduction and fixation of the dislocated, posterolateral key fragment of the distal tibia using a posterolateral approach resulted in a more accurate fracture reduction and significantly better functional outcome 12 months after surgery. In addition, no increased rate of postoperative complications, or extended hospital stay was observed but there was less severe post-traumatic joint arthritis. The results of this study suggest that in complex ankle factures the open fixation of the dislocated posterolateral fragment is recommended as an alternative surgical procedure and may be beneficial for both clinical and radiological long-term outcomes. Georg Thieme Verlag KG Stuttgart · New York.

Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation.

PubMed

Guo, Xuesong; Wu, Pianpian; Ding, Wenjie; Zhang, Weiyi; Li, Lin

2014-08-01

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study, airborne microorganisms generated from a wastewater treatment station (WWTS) that uses an oxidation ditch process were diminished by ventilation. Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups, concentrations, size distributions, and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m³ of airborne bacteria and 926 ± 132 CFU/m³ of airborne fungi present in the WWTS bioaerosol. Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after 4 hr of air exchange. The highest removal (92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65-1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away, which led to the relatively easy reduction of bioaerosol particles 0.65-1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces. Copyright © 2014. Published by Elsevier B.V.

Proteoglycan depletion and size reduction in lesions of early grade chondromalacia of the patella.

PubMed Central

Väätäinen, U; Häkkinen, T; Kiviranta, I; Jaroma, H; Inkinen, R; Tammi, M

1995-01-01

OBJECTIVE--To determine the content and molecular size of proteoglycans (PGs) in patellar chondromalacia (CM) and control cartilages as a first step in investigating the role of matrix alterations in the pathogenesis of this disease. METHODS--Chondromalacia tissue from 10 patients was removed with a surgical knife. Using identical techniques, apparently healthy cartilage of the same site was obtained from 10 age matched cadavers (mean age 31 years in both groups). Additional pathological cartilage was collected from 67 patients with grades II-IV CM (classified according to Outerbridge) using a motorised shaver under arthroscopic control. The shaved cartilage chips were collected with a dense net from the irrigation fluid of the shaver. The content of tissue PGs was determined by Safranin O precipitation or uronic acid content, and the molecular size by mobility on agarose gel electrophoresis. RESULTS--The mean PG content of the CM tissue samples with a knife was dramatically reduced, being only 15% of that in controls. The cartilage chips collected from shaving operations of grades II, III, and IV CM showed a decreasing PG content: 9%, 5%, and 1% of controls, respectively. Electrophoretic analysis of PGs extracted with guanidium chloride from the shaved tissue samples suggested a significantly reduced size of aggrecans in the mild (grade II) lesions. CONCLUSION--These data show that there is already a dramatic and progressive depletion of PGs in CM grade II lesions. This explains the softening of cartilage, a typical finding in the arthroscopic examination of CM. The PG size reduction observed in grade II implicates proteolytic attack as a factor in the pathogenesis of CM. Images PMID:7492223

The relevance of grain dissection for grain size reduction in polar ice: insights from numerical models and ice core microstructure analysis

NASA Astrophysics Data System (ADS)

Steinbach, Florian; Kuiper, Ernst-Jan N.; Eichler, Jan; Bons, Paul D.; Drury, Martyn R.; Griera, Albert; Pennock, Gill M.; Weikusat, Ilka

2017-09-01

The flow of ice depends on the properties of the aggregate of individual ice crystals, such as grain size or lattice orientation distributions. Therefore, an understanding of the processes controlling ice micro-dynamics is needed to ultimately develop a physically based macroscopic ice flow law. We investigated the relevance of the process of grain dissection as a grain-size-modifying process in natural ice. For that purpose, we performed numerical multi-process microstructure modelling and analysed microstructure and crystallographic orientation maps from natural deep ice-core samples from the North Greenland Eemian Ice Drilling (NEEM) project. Full crystallographic orientations measured by electron backscatter diffraction (EBSD) have been used together with c-axis orientations using an optical technique (Fabric Analyser). Grain dissection is a feature of strain-induced grain boundary migration. During grain dissection, grain boundaries bulge into a neighbouring grain in an area of high dislocation energy and merge with the opposite grain boundary. This splits the high dislocation-energy grain into two parts, effectively decreasing the local grain size. Currently, grain size reduction in ice is thought to be achieved by either the progressive transformation from dislocation walls into new high-angle grain boundaries, called subgrain rotation or polygonisation, or bulging nucleation that is assisted by subgrain rotation. Both our time-resolved numerical modelling and NEEM ice core samples show that grain dissection is a common mechanism during ice deformation and can provide an efficient process to reduce grain sizes and counter-act dynamic grain-growth in addition to polygonisation or bulging nucleation. Thus, our results show that solely strain-induced boundary migration, in absence of subgrain rotation, can reduce grain sizes in polar ice, in particular if strain energy gradients are high. We describe the microstructural characteristics that can be used to identify grain dissection in natural microstructures.

Effect of caliber size and fat level on the inactivation of E. coli O157:H7 in dry fermented sausages.

PubMed

De Souza, James; Ahmed, Rafath; Strange, Philip; Barbut, Shai; Balamurugan, S

2018-02-02

Dry fermented sausages (DFS) have been subject to numerous validation studies, as pathogen reduction heavily relies on both ingredients and processing. In this study the effect of product caliber size (32, 55, 80mm), and fat level (low, 9.67%; high, 18.46% wt/wt) on the inactivation of E. coli O157:H7 during DFS production was examined. Sausages containing a five-strain cocktail of E. coli O157:H7 at 10 7 CFU/g were manufactured and monitored for changes in physicochemical properties and inoculated E. coli O157:H7 numbers were enumerated during the DFS production stages and log reduction rates were calculated. Significant (P<0.01) reduction in pH from 5.9 to 4.9 was observed in all sausages within 72h of fermentation; however, the observed pH reduction was not significantly (P>0.05) different among sausages of different caliber size or fat levels. No significant (P>0.05) reduction in a w was observed during fermentation of the sausages. However, during the drying phase, sausages with larger caliber sizes required a significantly longer duration of drying to achieve the same a w of smaller caliber size sausages. For instance, to achieve an a w of ≤0.9, following 5days of fermentation/curing, 80mm caliber sausages required up to 27days of drying compared with 13 and 6days for 55 and 32mm caliber size sausages, respectively. Fat levels on the other hand did not significantly (P>0.05) effect the reduction of a w during drying of the sausages. During the fermentation stage there was a significant and rapid reduction in E. coli O157:H7 counts by about 1.1- to 1.4-log units, but was not significantly different among sausages of different caliber size and fat levels. Considering the whole process, only caliber size had a significant effect on log reduction of E. coli O157:H7. ANOVA of log reduction rates of E. coli O157:H7 among sausages of different caliber size and fat levels revealed no significant differences during the fermentation, however, during the drying of the sausages, log reduction rate of E. coli O157:H7 was significantly (P<0.01) lower in sausages with larger caliber sizes and higher fat levels. For instance, log reduction rates for E. coli O157:H7 in high fat large caliber sausages was the lowest at -0.082±0.004 log CFU/g/day compared to all other fat and caliber size combinations. These results suggest that DFS manufacturers producing higher fat and large caliber size products need to consider longer drying periods to achieve the required 5-log inactivation of E. coli O157:H7. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

The effects of cold rolling and the subsequent heat treatments on the shape memory and the superelasticity characteristics of Cu73Al16Mn11 shape memory alloy

NASA Astrophysics Data System (ADS)

Babacan, N.; Ma, J.; Turkbas, O. S.; Karaman, I.; Kockar, B.

2018-01-01

In the present study, the effect of thermo-mechanical treatments on the shape memory and the superelastic characteristics of Cu73Al16Mn11 (at%) shape memory alloy were investigated. 10%, 50% and 70% cold rolling and subsequent heat treatment processes were conducted to achieve strengthening via grain size refinement. 70% grain size reduction compared to the homogenized condition was obtained using 70% cold rolling and subsequent recrystallization heat treatment technique. Moreover, 10% cold rolling was applied to homogenized specimen to reveal the influence of the low percentage cold rolling reduction with no heat treatment on shape memory properties of Cu73Al16Mn11 (at%) alloy. Stress free transformation temperatures, monotonic tension and superelasticity behaviors of these samples were compared with those of the as-aged sample. Isobaric heating-cooling experiments were also conducted to see the dimensional stability of the samples as a function of applied stress. The 70% grain-refined sample exhibited better dimensional stability showing reduced residual strain levels upon thermal cycling under constant stress compared with the as-aged material. However, no improvement was achieved with grain size reduction in the superelasticity experiments. This distinctive observation was attributed to the difference in the magnitude of the stress levels achieved during two different types of experiments which were the isobaric heating-cooling and superelasticity tests. Intergranular fracture due to the stress concentration overcame the strengthening effect via grain refinement in the superelasticity tests at higher stress values. On the other hand, the strength of the material and resistance of material against plastic deformation upon phase transformation were increased as a result of the grain refinement at lower stress values in the isobaric heating-cooling experiments.

Localized Harmonic Motion Imaging for Focused Ultrasound Surgery Targeting

PubMed Central

Curiel, Laura; Hynynen, Kullervo

2011-01-01

Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized harmonic motion (LHM) to detect changes in tissues during focused ultrasound surgery (FUS) has been proposed to control the exposure. This technique can potentially be used as well for targeting imaging. In the present study we evaluated the potential of using LHM to detect changes in stiffness and the feasibility of using it for imaging purposes in phantoms and in vivo tumor detection. A single-element FUS transducer (80 mm focal length, 100 mm diameter, 1.485 MHz) was used for inducing a localized harmonic motion and a separate ultrasound diagnostic transducer excited by a pulser/receiver (5 kHz PRF, 5 MHz) was used to track motion. The motion was estimated using cross-correlation techniques on the acquired RF signal. Silicon phantom studies were performed in order to determine the size of inclusion that was possible to detect using this technique. Inclusions were discerned from the surroundings as a reduction on LHM amplitude and it was possible to depict inclusions as small as 4 mm. The amplitude of the induced LHM was always lower at the inclusions as compared with the one obtained at the surroundings. Ten New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region. Tumors (as small as 10 mm in length and 4 mm in width) were discerned from the surroundings as a reduction on LHM amplitude. PMID:21683514

Large-scale inverse model analyses employing fast randomized data reduction

NASA Astrophysics Data System (ADS)

Lin, Youzuo; Le, Ellen B.; O'Malley, Daniel; Vesselinov, Velimir V.; Bui-Thanh, Tan

2017-08-01

When the number of observations is large, it is computationally challenging to apply classical inverse modeling techniques. We have developed a new computationally efficient technique for solving inverse problems with a large number of observations (e.g., on the order of 107 or greater). Our method, which we call the randomized geostatistical approach (RGA), is built upon the principal component geostatistical approach (PCGA). We employ a data reduction technique combined with the PCGA to improve the computational efficiency and reduce the memory usage. Specifically, we employ a randomized numerical linear algebra technique based on a so-called "sketching" matrix to effectively reduce the dimension of the observations without losing the information content needed for the inverse analysis. In this way, the computational and memory costs for RGA scale with the information content rather than the size of the calibration data. Our algorithm is coded in Julia and implemented in the MADS open-source high-performance computational framework (http://mads.lanl.gov). We apply our new inverse modeling method to invert for a synthetic transmissivity field. Compared to a standard geostatistical approach (GA), our method is more efficient when the number of observations is large. Most importantly, our method is capable of solving larger inverse problems than the standard GA and PCGA approaches. Therefore, our new model inversion method is a powerful tool for solving large-scale inverse problems. The method can be applied in any field and is not limited to hydrogeological applications such as the characterization of aquifer heterogeneity.

A systematic comparison of the closed shoulder reduction techniques.

PubMed

Alkaduhimi, H; van der Linde, J A; Willigenburg, N W; van Deurzen, D F P; van den Bekerom, M P J

2017-05-01

To identify the optimal technique for closed reduction for shoulder instability, based on success rates, reduction time, complication risks, and pain level. A PubMed and EMBASE query was performed, screening all relevant literature of closed reduction techniques mentioning the success rate written in English, Dutch, German, and Arabic. Studies with a fracture dislocation or lacking information on success rates for closed reduction techniques were excluded. We used the modified Coleman Methodology Score (CMS) to assess the quality of included studies and excluded studies with a poor methodological quality (CMS < 50). Finally, a meta-analysis was performed on the data from all studies combined. 2099 studies were screened for their title and abstract, of which 217 studies were screened full-text and finally 13 studies were included. These studies included 9 randomized controlled trials, 2 retrospective comparative studies, and 2 prospective non-randomized comparative studies. A combined analysis revealed that the scapular manipulation is the most successful (97%), fastest (1.75 min), and least painful reduction technique (VAS 1,47); the "Fast, Reliable, and Safe" (FARES) method also scores high in terms of successful reduction (92%), reduction time (2.24 min), and intra-reduction pain (VAS 1.59); the traction-countertraction technique is highly successful (95%), but slower (6.05 min) and more painful (VAS 4.75). For closed reduction of anterior shoulder dislocations, the combined data from the selected studies indicate that scapular manipulation is the most successful and fastest technique, with the shortest mean hospital stay and least pain during reduction. The FARES method seems the best alternative.

A review on biogenic synthesis of ZnO nanoparticles using plant extracts and microbes: A prospect towards green chemistry.

PubMed

Ahmed, Shakeel; Annu; Chaudhry, Saif Ali; Ikram, Saiqa

2017-01-01

Nanotechnology is emerging as an important area of research with its tremendous applications in all fields of science, engineering, medicine, pharmacy, etc. It involves the materials and their applications having one dimension in the range of 1-100nm. Generally, various techniques are used for syntheses of nanoparticles (NPs) viz. laser ablation, chemical reduction, milling, sputtering, etc. These conventional techniques e.g. chemical reduction method, in which various hazardous chemicals are used for the synthesis of NPs later become liable for innumerable health risks due to their toxicity and endangering serious concerns for environment, while other approaches are expensive, need high energy for the synthesis of NPs. However, biogenic synthesis method to produce NPs is eco-friendly and free of chemical contaminants for biological applications where purity is of concerns. In biological method, different biological entities such as extract, enzymes or proteins of a natural product are used to reduce and stabilised formation of NPs. The nature of these biological entities also influence the structure, shape, size and morphology of synthesized NPs. In this review, biogenic synthesis of zinc oxide (ZnO) NPs, procedures of syntheses, mechanism of formation and their various applications have been discussed. Various entities such as proteins, enzymes, phytochemicals, etc. available in the natural reductants are responsible for synthesis of ZnO NPs. Copyright © 2016 Elsevier B.V. All rights reserved.

Wispy Prosthesis: A Novel Method in Denture Weight Reduction

PubMed Central

Anne, Gopinadh; Budeti, Sreedevi; Anche, Sampath Kumar; Zakkula, Srujana; Atla, Jyothi; Jyothula, Ravi Rakesh Dev; Peddinti, Vijaya Kumar

2016-01-01

Introduction Stability and retention of the denture becomes at stake with the increase in weight of the denture prosthesis. As a consequence, different materials and methods have been introduced to overcome these issues but denture weight reduction still remains to be a cumbersome and strenuous procedure. Aim To introduce a novel technique for the fabrication of denture prosthesis where in the weight of the denture will not affect the retention and stability of the denture. Materials and Methods Four groups with a sample size of 10 each, were included where in one group was control and other three were study groups. The control group samples were made completely solid and the study group samples were packed with materials like bean balls, cellulose balls and polyacrylic fibers. The weight of all the samples of each study group was measured and compared with the control group. The observations were analyzed statistically by paired t-test. Results It was observed that the bean balls group produced a weight reduction of 31.3%, cellulose balls group 27.4% and polyacrylic fibers group 24.5% when compared to that of the control group. Conclusion This novel technique will eliminate the problems that were associated in creating hollowness and at the same time will reduce the weight of the prosthesis and among all the study groups, bean balls group were found to reduce maximum weight of the prosthesis. PMID:27190947

Wispy Prosthesis: A Novel Method in Denture Weight Reduction.

PubMed

Anne, Gopinadh; Budeti, Sreedevi; Anche, Sampath Kumar; Zakkula, Srujana; Atla, Jyothi; Jyothula, Ravi Rakesh Dev; Appana, Krishna Chaitanya; Peddinti, Vijaya Kumar

2016-04-01

Stability and retention of the denture becomes at stake with the increase in weight of the denture prosthesis. As a consequence, different materials and methods have been introduced to overcome these issues but denture weight reduction still remains to be a cumbersome and strenuous procedure. To introduce a novel technique for the fabrication of denture prosthesis where in the weight of the denture will not affect the retention and stability of the denture. Four groups with a sample size of 10 each, were included where in one group was control and other three were study groups. The control group samples were made completely solid and the study group samples were packed with materials like bean balls, cellulose balls and polyacrylic fibers. The weight of all the samples of each study group was measured and compared with the control group. The observations were analyzed statistically by paired t-test. It was observed that the bean balls group produced a weight reduction of 31.3%, cellulose balls group 27.4% and polyacrylic fibers group 24.5% when compared to that of the control group. This novel technique will eliminate the problems that were associated in creating hollowness and at the same time will reduce the weight of the prosthesis and among all the study groups, bean balls group were found to reduce maximum weight of the prosthesis.

Effects of 5 weeks of lower limb suspension on muscle size and strength

NASA Technical Reports Server (NTRS)

Tesch, P. A.; Ploutz, L. L.; Dudley, G. A.

1994-01-01

Lack of weight-bearing, as occurs in space, appears to be associated with reductions in strength and mass of skeletal muscle. Very limited data, however, is at hand describing changes in skeletal muscle size and function following manned space missions. Our current knowledge therefore is mainly based on studies of space flown rats. It is obvious though that this information, only in part can be extrapolated to humans. A few bed rest studies have demonstrated that decreases in strength and muscle size are substantial. At this time, however, the magnitude or time course of such changes either in response to space flight or simulations of microgravity have not been defined. In the last few years we have employed a human model to simulate unloading of lower limb skeletal muscles that occurs in microgravity. This model was essentially adopted from the rat hindlimb suspension technique. The purpose of this study was to assess the magnitude of decreases in muscle strength and size as a result of five weeks of unilateral lower limb suspension.

Finding minimum spanning trees more efficiently for tile-based phase unwrapping

NASA Astrophysics Data System (ADS)

Sawaf, Firas; Tatam, Ralph P.

2006-06-01

The tile-based phase unwrapping method employs an algorithm for finding the minimum spanning tree (MST) in each tile. We first examine the properties of a tile's representation from a graph theory viewpoint, observing that it is possible to make use of a more efficient class of MST algorithms. We then describe a novel linear time algorithm which reduces the size of the MST problem by half at the least, and solves it completely at best. We also show how this algorithm can be applied to a tile using a sliding window technique. Finally, we show how the reduction algorithm can be combined with any other standard MST algorithm to achieve a more efficient hybrid, using Prim's algorithm for empirical comparison and noting that the reduction algorithm takes only 0.1% of the time taken by the overall hybrid.

Complete reduction of high-density UO2 to metallic U in molten Li2O-LiCl

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Lee, Jeong

2017-10-01

The large size and high density of spent fuel pellets make it difficult to use the pellets directly in electrolytic reduction (also called as oxide reduction, OR) for pyroprocessing owing to the slow diffusion of molten Li2O-LiCl salt electrolyte into the pellets. In this study, we investigated complete OR of high-density UO2 to metallic U without any remaining UO2. Only partial reductions near the surface of high-density UO2 pellets were observed under operation conditions employing fast electrolysis rate that allowed previously complete reduction of low-density UO2 pellets. Complete reduction of high-density UO2 pellets was observed at fast electrolysis rate when the pellet size was reduced. The complete reduction of high-density UO2 pellets without size reduction was achieved at slow electrolysis rate, which allowed sufficient chemical reduction of UO2 with the lithium metal generated by the cathode reaction.

A vertical-energy-thresholding procedure for data reduction with multiple complex curves.

PubMed

Jung, Uk; Jeong, Myong K; Lu, Jye-Chyi

2006-10-01

Due to the development of sensing and computer technology, measurements of many process variables are available in current manufacturing processes. It is very challenging, however, to process a large amount of information in a limited time in order to make decisions about the health of the processes and products. This paper develops a "preprocessing" procedure for multiple sets of complicated functional data in order to reduce the data size for supporting timely decision analyses. The data type studied has been used for fault detection, root-cause analysis, and quality improvement in such engineering applications as automobile and semiconductor manufacturing and nanomachining processes. The proposed vertical-energy-thresholding (VET) procedure balances the reconstruction error against data-reduction efficiency so that it is effective in capturing key patterns in the multiple data signals. The selected wavelet coefficients are treated as the "reduced-size" data in subsequent analyses for decision making. This enhances the ability of the existing statistical and machine-learning procedures to handle high-dimensional functional data. A few real-life examples demonstrate the effectiveness of our proposed procedure compared to several ad hoc techniques extended from single-curve-based data modeling and denoising procedures.

In situ X-ray absorption fine structure analysis of redox reactions of nickel species with variable particle sizes supported on silica

NASA Astrophysics Data System (ADS)

Yamamoto, Yusaku; Suzuki, Atsushi; Tsutsumi, Naoki; Katagiri, Masaki; Yamashita, Shohei; Niwa, Yasuhiro; Katayama, Misaki; Inada, Yasuhiro

2018-02-01

The chemical states of Ni species were systematically investigated using an in situ XAFS technique for a series of SiO2-supported Ni catalysts with different Ni particle sizes. The Ni particles were refined by varying the Ni loading in the range between 0.10 and 5 wt% and by adding citric acid into the precursor solution. An in situ observation cell for fluorescence-yield XAFS measurements was developed for the dilute Ni catalysts. The chemical state of the supported Ni species converted between Ni(0) and NiO, and no other stable species were formed during the temperature-programmed oxidation and reduction processes. Refinement of the Ni particles resulted in decreasing the oxidation temperature and increasing the reduction temperature. These shifts were explained by the affinity of NiO to SiO2, and more effective stabilization was thus anticipated for flattened small NiO particles with an increased contact area. In addition, the inhomogeneous distribution of small Ni particles observed for dilute catalysts was explained in terms of the precursor solution volume when nuclei of the precursor compound precipitated on SiO2 during the drying process.

Comparison of four different reduction methods for anterior dislocation of the shoulder.

PubMed

Guler, Olcay; Ekinci, Safak; Akyildiz, Faruk; Tirmik, Uzeyir; Cakmak, Selami; Ugras, Akin; Piskin, Ahmet; Mahirogullari, Mahir

2015-05-28

Shoulder dislocations account for almost 50% of all major joint dislocations and are mainly anterior. The aim is a comparative retrospective study of different reduction maneuvers without anesthesia to reduce the dislocated shoulder. Patients were treated with different reduction maneuvers, including various forms of traction and external rotation, in the emergency departments of four training hospitals between 2009 and 2012. Each of the four hospitals had different treatment protocols for reduction and applying one of four maneuvers: Spaso, Chair, Kocher, and Matsen methods. Thirty-nine patients were treated by the Spaso method, 47 by the Chair reduction method, 40 by the Kocher method, and 27 patients by Matsen's traction-countertraction method. All patients' demographic data were recorded. Dislocation number, reduction time, time interval between dislocation and reduction, and associated complications, pre- and post-reduction period, were recorded prospectively. No anesthetic method was used for the reduction. All of the methods used included traction and some external rotation. The Chair method had the shortest reduction time. All surgeons involved in the study agreed that the Kocher and Matsen methods needed more force for the reduction. Patients could contract their muscles because of the pain in these two methods. The Spaso method includes flexion of the shoulder and blocks muscle contraction somewhat. The Chair method was found to be the easiest because the patients could not contract their muscles while sitting on a chair with the affected arm at their side. We suggest that the Chair method is an effective and fast reduction maneuver that may be an alternative for the treatment of anterior shoulder dislocations. Further prospective studies with larger sample size are needed to compare safety of different reduction techniques.

Effect of respiratory gating on reducing lung motion artifacts in PET imaging of lung cancer.

PubMed

Nehmeh, S A; Erdi, Y E; Ling, C C; Rosenzweig, K E; Squire, O D; Braban, L E; Ford, E; Sidhu, K; Mageras, G S; Larson, S M; Humm, J L

2002-03-01

Positron emission tomography (PET) has shown an increase in both sensitivity and specificity over computed tomography (CT) in lung cancer. However, motion artifacts in the 18F fluorodioxydoglucose (FDG) PET images caused by respiration persists to be an important factor in degrading PET image quality and quantification. Motion artifacts lead to two major effects: First, it affects the accuracy of quantitation, producing a reduction of the measured standard uptake value (SUV). Second, the apparent lesion volume is overestimated. Both impact upon the usage of PET images for radiation treatment planning. The first affects the visibility, or contrast, of the lesion. The second results in an increase in the planning target volume, and consequently a greater radiation dose to the normal tissues. One way to compensate for this effect is by applying a multiple-frame capture technique. The PET data are then acquired in synchronization with the respiratory motion. Reduction in smearing due to gating was investigated in both phantoms and patient studies. Phantom studies showed a dependence of the reduction in smearing on the lesion size, the motion amplitude, and the number of bins used for data acquisition. These studies also showed an improvement in the target-to-background ratio, and a more accurate measurement of the SUV. When applied to one patient, respiratory gating showed a 28% reduction in the total lesion volume, and a 56.5% increase in the SUV. This study was conducted as a proof of principle that a gating technique can effectively reduce motion artifacts in PET image acquisition.

Experimental study of microbubble drag reduction on an axisymmetric body

NASA Astrophysics Data System (ADS)

Song, Wuchao; Wang, Cong; Wei, Yingjie; Zhang, Xiaoshi; Wang, Wei

2018-01-01

Microbubble drag reduction on the axisymmetric body is experimentally investigated in the turbulent water tunnel. Microbubbles are created by injecting compressed air through the porous medium with various average pore sizes. The morphology of microbubble flow and the size distribution of microbubble are observed by the high-speed visualization system. Drag measurements are obtained by the balance which is presented as the function of void ratio. The results show that when the air injection flow rate is high, uniformly dispersed microbubble flow is coalesced into an air layer with the larger increment rate of drag reduction ratio. The diameter distributions of microbubble under various conditions are submitted to normal distribution. Microbubble drag reduction can be divided into three distinguishable regions in which the drag reduction ratio experiences increase stage, rapid increase stage and stability stage, respectively, corresponding to the various morphologies of microbubble flow. Moreover, drag reduction ratio increases with the decreasing pore sizes of porous medium at the identical void ratio in the area of low speeds, while the effect of pore sizes on drag reduction is reduced gradually until it disappears with the increasing free stream speeds, which indicates that smaller microbubbles have better efficiency in drag reduction. This research results help to improve the understanding of microbubble drag reduction and provides helpful references for practical applications.

The light-induced reduction of horizontal cell receptive field size in the goldfish retina involves nitric oxide.

PubMed

Daniels, Bryan A; Baldridge, William H

2011-03-01

Horizontal cells of the vertebrate retina have large receptive fields as a result of extensive gap junction coupling. Increased ambient illumination reduces horizontal cell receptive field size. Using the isolated goldfish retina, we have assessed the contribution of nitric oxide to the light-dependent reduction of horizontal cell receptive field size. Horizontal cell receptive field size was assessed by comparing the responses to centered spot and annulus stimuli and from the responses to translated slit stimuli. A period of steady illumination decreased the receptive field size of horizontal cells, as did treatment with the nitric oxide donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (100 μM). Blocking the endogenous production of nitric oxide with the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (1 mM), decreased the light-induced reduction of horizontal cell receptive field size. These findings suggest that nitric oxide is involved in light-induced reduction of horizontal cell receptive field size. Copyright © Cambridge University Press, 2011

Application of 3D printing rapid prototyping-assisted percutaneous fixation in the treatment of intertrochanteric fracture.

PubMed

Zheng, Sheng-Nai; Yao, Qing-Qiang; Mao, Feng-Yong; Zheng, Peng-Fei; Tian, Shu-Chang; Li, Jia-Yi; Yu, Yi-Fan; Liu, Shuai; Zhou, Jin; Hu, Jun; Xu, Yan; Tang, Kai; Lou, Yue; Wang, Li-Ming

2017-10-01

The aim of the present study was to investigate the application of 3D printing (3DP) rapid prototyping (RP) technique-assisted percutaneous fixation in the treatment of femoral intertrochanteric fracture (ITF) using proximal femoral nail anti-rotation (PFNA). A total of 39 patients with unstable ITF were included in the current study. Patients were divided into two groups: 19 patients were examined using computed tomography scanning and underwent PFNA with SDP-RP whereas the other 20 patients underwent conventional PFNA treatment. Anatomical data were converted from the Digital Imaging and Communications in Medicine format to the stereolithography format using M3D software. The 3DP-RP model was established using the fused deposition modeling technique and the length and diameter of the main screw blade was measured during the simulation. The postoperative femoral neck-shaft angle (NSA), surgery duration, intraoperative and postoperative blood loss, and the duration of hospital stay were recorded and compared with the corresponding values in conventional surgery. No significant differences were observed in mean PFNA size between the implants used and the preoperative planning estimates. It was demonstrated that the 3DP-RP assisted procedure resulted in more effective reduction of the NSA. Furthermore, patients undergoing 3DP-RP experienced a significant reduction in duration of surgery (P<0.01), as well as reductions in intraoperative (P=0.02) and postoperative (P=0.03) blood loss, compared with conventional surgery. At 6 months post-surgery, no cases of hip varus/vague deformities or implant failure were observed in patients that underwent either the 3DP-RP-assisted or conventional procedure. The results of the present study suggest that the 3DP-RP technique is able to create an accurate model of the ITF, which facilitates surgical planning and fracture reduction, thus improving the efficiency of PFNA surgery for ITFs.

Impact of Simulation Technology on Die and Stamping Business

NASA Astrophysics Data System (ADS)

Stevens, Mark W.

2005-08-01

Over the last ten years, we have seen an explosion in the use of simulation-based techniques to improve the engineering, construction, and operation of GM production tools. The impact has been as profound as the overall switch to CAD/CAM from the old manual design and construction methods. The changeover to N/C machining from duplicating milling machines brought advances in accuracy and speed to our construction activity. It also brought significant reductions in fitting sculptured surfaces. Changing over to CAD design brought similar advances in accuracy, and today's use of solid modeling has enhanced that accuracy gain while finally leading to the reduction in lead time and cost through the development of parametric techniques. Elimination of paper drawings for die design, along with the process of blueprinting and distribution, provided the savings required to install high capacity computer servers, high-speed data transmission lines and integrated networks. These historic changes in the application of CAE technology in manufacturing engineering paved the way for the implementation of simulation to all aspects of our business. The benefits are being realized now, and the future holds even greater promise as the simulation techniques mature and expand. Every new line of dies is verified prior to casting for interference free operation. Sheet metal forming simulation validates the material flow, eliminating the high costs of physical experimentation dependent on trial and error methods of the past. Integrated forming simulation and die structural analysis and optimization has led to a reduction in die size and weight on the order of 30% or more. The latest techniques in factory simulation enable analysis of automated press lines, including all stamping operations with corresponding automation. This leads to manufacturing lines capable of running at higher levels of throughput, with actual results providing the capability of two or more additional strokes per minute. As we spread these simulation techniques to the balance of our business, from blank de-stacking to the racking of parts, we anticipate continued reduction in lead-time and engineering expense while improving quality and start-up execution. The author will provide an overview of technology and business evolution of the math-based process that brought an historical transition and revitalization to the die and stamping industry in the past decade. Finally, the author will give an outlook for future business needs and technology development directions.

Nanoparticles in the pharmaceutical industry and the use of supercritical fluid technologies for nanoparticle production.

PubMed

Sheth, Pratik; Sandhu, Harpreet; Singhal, Dharmendra; Malick, Waseem; Shah, Navnit; Kislalioglu, M Serpil

2012-05-01

Poor aqueous solubility of drug candidates is a major challenge for the pharmaceutical scientists involved in drug development. Particle size reduction appears as an effective and versatile option for solubility improvement. Nanonization is an attractive solution to improve the bioavailability of the poorly soluble drugs, improved therapies, in vivo imaging, in vitro diagnostics and for the production of biomaterials and active implants. In drug delivery, application of nanotechnology is commonly referred to as Nano Drug Delivery Systems (NDDS). In this article, commercially available nanosized drugs, their dosage forms and proprietors, as well as the methods used for preparation like milling, high pressure homogenization, vacuum deposition, and high temperature evaporation were listed. Unlike the traditional methods used for the particle size reduction, supercritical fluid-processing techniques offer advantages ranging from superior particle size control to clean processing. The primary focus of this review article is the use of supercritical CO2 based technologies for small particle generation. Particles that have the smooth surfaces, small particle size and distribution and free flowing can be obtained with particular SCF techniques. In almost all techniques, the dominating process variables may be thermodynamic and aerodynamic in nature, and the design of the particle collection environment. Rapid Expansion of Supercritical Solutions (RESS), Supercritical Anti Solvent (SAS) and Particles from Gas Saturated Solutions (PGSS) are three groups of processes which lead to the production of fine and monodisperse powders. Few of them may also control crystal polymorphism. Among the aforementioned processes, RESS involves dissolving a drug in a supercritical fluid (SCF) and passing it through an appropriate nozzle. Rapid depressurization of this solution causes an extremely rapid nucleation of the product. This process has been known for a long time but its application is limited. Carbon dioxide, which is the only supercritical fluid that is preferentially used in pharmaceutical processes, is not a good solvent for many Active Pharmaceutical Ingredients (API). Various researchers have modified the RESS process to overcome its solubilizing limitations, by introducing RESOLV, RESAS, and RESS-SC. Overall, all RESS based processes are difficult to scale up. The SAS processes are based on decreasing the solvent power of a polar organic solvent in which the substrate (API & polymer of interest) is dissolved, by saturating it with carbon dioxide (CO2) at supercritical conditions. CO2 causes precipitation and recrystalization of the drug. SAS is scalable and can be applied to a wide variety of APIs and polymers. Minor modifications of basic SAS process include GAS, ASES, SAS-DEM and SAS-EM. Processes where SCF is used as an anti solvent and dispersing agent include SEDS, SAA, and A-SAIS. The mechanisms and applications of these processes were briefly discussed. In PGSS, CO2 is dissolved in organic solutions or melted compounds and it is successfully used for manufacturing drug products as well as for drying purposes. The two widely used methods, PGSSdrying and CAN-BD SCF, were also included in discussions. Among the limitations of the techniques involved, the poor solvent power of CO2, the cost and necessity of voluminous usage of the CO2 can be mentioned. There is still confusion in contribution of each variable on the particle morphology and properties regardless of the number of mechanistic studies available. The advantages of especially SAS and PGSS based techniques are the production of the nano or micro sized spherical particles with smooth surfaces and narrow particle size distribution. Regardless of its advantages, the reasons why 25 years of active research, and more than 10 years of process development could not promote the use of (SCF) technology, and produced only few commercial drug products, necessitate further evaluation of this technique.

Synthesis of Pt nanoparticles as catalysts of oxygen reduction with microbubble-assisted low-voltage and low-frequency solution plasma processing

NASA Astrophysics Data System (ADS)

Horiguchi, Genki; Chikaoka, Yu; Shiroishi, Hidenobu; Kosaka, Shinpei; Saito, Morihiro; Kameta, Naohiro; Matsuda, Naoki

2018-04-01

In the preparation of metallic nanoparticles by conventional solution plasma (SP) techniques, unstable plasma emission becomes an issue when the voltage and frequency of the waves applied between two electrodes placed in solution are lowered to avoid the boiling of the solution. In this study, we confirm that, in the presence of microbubbles, plasma is generated stably at low voltage (440 V) and low frequency (50-100 Hz) and small-size (≤10 nm) Pt nanoparticles (PtNPs) are synthesized in succession using a flow cell. The smallest PtNPs, ∼3.3 nm in diameter, are obtained using half-wave rectification, a tungsten wire anode, and a platinum wire cathode. The PtNPs are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimeter-differential thermal analysis. The oxygen reduction reaction (ORR) is investigated in 0.1 M HClO4 solution on carbon-supported PtNPs using a rotating ring-disk electrode. The catalytic activities per initial electrochemical active surface area of the carbon-supported PtNPs synthesized employing the low-voltage, low-frequency (LVLF)-SP technique is higher than that of the commercially available 20 wt% Pt on Vulcan XC-72R. These results indicate that the LVLF-SP technique is a promising approach to producing carbon-supported PtNPs that catalyze ORR with low energy consumption.

Evaluation of Classifier Performance for Multiclass Phenotype Discrimination in Untargeted Metabolomics.

PubMed

Trainor, Patrick J; DeFilippis, Andrew P; Rai, Shesh N

2017-06-21

Statistical classification is a critical component of utilizing metabolomics data for examining the molecular determinants of phenotypes. Despite this, a comprehensive and rigorous evaluation of the accuracy of classification techniques for phenotype discrimination given metabolomics data has not been conducted. We conducted such an evaluation using both simulated and real metabolomics datasets, comparing Partial Least Squares-Discriminant Analysis (PLS-DA), Sparse PLS-DA, Random Forests, Support Vector Machines (SVM), Artificial Neural Network, k -Nearest Neighbors ( k -NN), and Naïve Bayes classification techniques for discrimination. We evaluated the techniques on simulated data generated to mimic global untargeted metabolomics data by incorporating realistic block-wise correlation and partial correlation structures for mimicking the correlations and metabolite clustering generated by biological processes. Over the simulation studies, covariance structures, means, and effect sizes were stochastically varied to provide consistent estimates of classifier performance over a wide range of possible scenarios. The effects of the presence of non-normal error distributions, the introduction of biological and technical outliers, unbalanced phenotype allocation, missing values due to abundances below a limit of detection, and the effect of prior-significance filtering (dimension reduction) were evaluated via simulation. In each simulation, classifier parameters, such as the number of hidden nodes in a Neural Network, were optimized by cross-validation to minimize the probability of detecting spurious results due to poorly tuned classifiers. Classifier performance was then evaluated using real metabolomics datasets of varying sample medium, sample size, and experimental design. We report that in the most realistic simulation studies that incorporated non-normal error distributions, unbalanced phenotype allocation, outliers, missing values, and dimension reduction, classifier performance (least to greatest error) was ranked as follows: SVM, Random Forest, Naïve Bayes, sPLS-DA, Neural Networks, PLS-DA and k -NN classifiers. When non-normal error distributions were introduced, the performance of PLS-DA and k -NN classifiers deteriorated further relative to the remaining techniques. Over the real datasets, a trend of better performance of SVM and Random Forest classifier performance was observed.

Suprachoroidal drainage with collagen sheet implant- a novel technique for non-penetrating glaucoma surgery.

PubMed

Szurman, Peter; Januschowski, Kai; Boden, Karl Thomas; Seuthe, Anna-Maria

2018-02-01

Our purpose was both to introduce the new technique of suprachoroidal drainage with collagen sheet implantation as a novel technique of non-penetrating glaucoma surgery and to present first results of a prospective pilot study. A superficial rectangular sclera flap of half-scleral thickness sized 4 × 4.5 mm is dissected anteriorly until clear cornea. Then, a second scleral flap is created underneath the first one sized 3.5x4mm and is cut down full-thickness to the choroid exposing the suprachoroidal space. The flap is then bluntly prepared until the scleral spur is reached. Sharp dissection above the sclera spur exposes Schlemm's canal, which is located directly anteriorly. Schlemm's canal is unroofed, juxtacanalicular meshwork is peeled and the deep flap is cut off at its base. An absorbable collagen sheet (Ologen®, Dahlhausen, Cologne, Germany) is placed into the suprachoroidal space at the level of the ciliary body, and the superficial sclera flap is sutured tightly to prevent leakage. We prospectively analyzed 65 eyes that underwent suprachoroidal drainage with collagen sheet implantation. Mean reduction of intraocular pressure after 3 months was 35.1% (from 21.0 ± 4.3 mmHg to 13.5 ± 3.4 mmHg)(p < 0.01) and after 12 months 35.6% (from 21.0 ± 4.3 mmHg to 13.5 ± 3.0  mmHg)(p < 0.01). The number of topical IOP-reducing medication decreased significantly from 3.5 ± 0.7 to 0.6 ± 0.9 and to 0.9 ± 1.1 after 3 and 12 months, respectively (p < 0.01). No serious complications occurred. Suprachoroidal drainage with collagen sheet implantation seems to be a safe and effective surgical technique for non-penetrating glaucoma surgery that yields the opportunity of a sufficient IOP reduction for eyes unsuitable for canaloplasty.

Contactless Abdominal Fat Reduction With Selective RF™ Evaluated by Magnetic Resonance Imaging (MRI): Case Study.

PubMed

Downie, Jeanine; Kaspar, Miroslav

2016-04-01

Noninvasive body shaping methods seem to be an ascending part of the aesthetics market. As a result, the pressure to develop reliable methods for the collection and presentation of their results has also increased. The most used techniques currently include ultrasound measurements of fat thickness in the treated area, caliper measurements, bioimpedance-based scale measurements or circumferential tape measurements. Although these are the most used techniques, almost all of them have some limitations in reproducibility and/or accuracy. This study shows Magnetic Resonance Imaging (MRI) as the new method for the presentation of results in the body shaping industry. Six subjects were treated by a contactless selective radiofrequency device (BTL Vanquish ME, BTL Industries Inc., Boston, MA). The MRI fat thickness was measured at the baseline and at 4-weeks following the treatment. In addition to MRI images and measurements, digital photographs and anthropometric evaluations such as weight, abdominal circumference, and caliper fat thickness measurements were recorded. Abdominal fat thickness measurements from the MRI were performed from the same slices determined by the same tissue artefacts. The MRI fat thickness difference between the baseline measurement and follow up visit showed an average reduction of 5.36 mm as calculated from the data of 5 subjects. One subject dropped out of study due to non-study related issues. The results were statistically significant based on the Student's T-test evaluation. Magnetic resonance imaging abdominal fat thickness measurements seems to be the best method for the evaluation of fat thickness reduction after non-invasive body shaping treatments. In this study, this method shows average fat thickness reduction of 5.36 mm while the weight of the subjects didn't change significantly. A large spot size measuring 1317 cm(2) (204 square inches) covers the abdomen flank to flank. The average thickness of 5.36 mm of the fat layer reduced under the applicator translates into significant cumulative circumferential reduction. The reduction was not related with dieting.

An investigation of kV CBCT image quality and dose reduction for volume-of-interest imaging using dynamic collimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, David, E-mail: david.parsons@dal.ca, E-mail: james.robar@cdha.nshealth.ca; Robar, James L., E-mail: david.parsons@dal.ca, E-mail: james.robar@cdha.nshealth.ca

2015-09-15

Purpose: The focus of this work was to investigate the improvements in image quality and dose reduction for volume-of-interest (VOI) kilovoltage-cone beam CT (CBCT) using dynamic collimation. Methods: A prototype iris aperture was used to track a VOI during a CBCT acquisition. The current aperture design is capable of 1D translation as a function of gantry angle and dynamic adjustment of the iris radius. The aperture occupies the location of the bow-tie filter on a Varian On-Board Imager system. CBCT and planar image quality were investigated as a function of aperture radius, while maintaining the same dose to the VOI,more » for a 20 cm diameter cylindrical water phantom with a 9 mm diameter bone insert centered on isocenter. Corresponding scatter-to-primary ratios (SPR) were determined at the detector plane with Monte Carlo simulation using EGSnrc. Dose distributions for various sizes VOI were modeled using a dynamic BEAMnrc library and DOSXYZnrc. The resulting VOI dose distributions were compared to full-field distributions. Results: SPR was reduced by a factor of 8.4 when decreasing iris diameter from 21.2 to 2.4 cm (at isocenter). Depending upon VOI location and size, dose was reduced to 16%–90% of the full-field value along the central axis plane and down to 4% along the axis of rotation, while maintaining the same dose to the VOI compared to full-field techniques. When maintaining constant dose to the VOI, this change in iris diameter corresponds to a factor increase of approximately 1.6 in image contrast and a factor decrease in image noise of approximately 1.2. This results in a measured gain in contrast-to-noise ratio by a factor of approximately 2.0. Conclusions: The presented VOI technique offers improved image quality for image-guided radiotherapy while sparing the surrounding volume of unnecessary dose compared to full-field techniques.« less

A quantitative comparison of noise reduction across five commercial (hybrid and model-based) iterative reconstruction techniques: an anthropomorphic phantom study.

PubMed

Patino, Manuel; Fuentes, Jorge M; Hayano, Koichi; Kambadakone, Avinash R; Uyeda, Jennifer W; Sahani, Dushyant V

2015-02-01

OBJECTIVE. The objective of our study was to compare the performance of three hybrid iterative reconstruction techniques (IRTs) (ASiR, iDose4, SAFIRE) and their respective strengths for image noise reduction on low-dose CT examinations using filtered back projection (FBP) as the standard reference. Also, we compared the performance of these three hybrid IRTs with two model-based IRTs (Veo and IMR) for image noise reduction on low-dose examinations. MATERIALS AND METHODS. An anthropomorphic abdomen phantom was scanned at 100 and 120 kVp and different tube current-exposure time products (25-100 mAs) on three CT systems (for ASiR and Veo, Discovery CT750 HD; for iDose4 and IMR, Brilliance iCT; and for SAFIRE, Somatom Definition Flash). Images were reconstructed using FBP and using IRTs at various strengths. Nine noise measurements (mean ROI size, 423 mm(2)) on extracolonic fat for the different strengths of IRTs were recorded and compared with FBP using ANOVA. Radiation dose, which was measured as the volume CT dose index and dose-length product, was also compared. RESULTS. There were no significant differences in radiation dose and image noise among the scanners when FBP was used (p > 0.05). Gradual image noise reduction was observed with each increasing increment of hybrid IRT strength, with a maximum noise suppression of approximately 50% (48.2-53.9%). Similar noise reduction was achieved on the scanners by applying specific hybrid IRT strengths. Maximum noise reduction was higher on model-based IRTs (68.3-81.1%) than hybrid IRTs (48.2-53.9%) (p < 0.05). CONCLUSION. When constant scanning parameters are used, radiation dose and image noise on FBP are similar for CT scanners made by different manufacturers. Significant image noise reduction is achieved on low-dose CT examinations rendered with IRTs. The image noise on various scanners can be matched by applying specific hybrid IRT strengths. Model-based IRTs attain substantially higher noise reduction than hybrid IRTs irrespective of the radiation dose.

Single Nanoparticle Plasmonic Sensors

PubMed Central

Sriram, Manish; Zong, Kelly; Vivekchand, S. R. C.; Gooding, J. Justin

2015-01-01

The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed. PMID:26473866

Reduction of a metapopulation genetic model to an effective one-island model

NASA Astrophysics Data System (ADS)

Parra-Rojas, César; McKane, Alan J.

2018-04-01

We explore a model of metapopulation genetics which is based on a more ecologically motivated approach than is frequently used in population genetics. The size of the population is regulated by competition between individuals, rather than by artificially imposing a fixed population size. The increased complexity of the model is managed by employing techniques often used in the physical sciences, namely exploiting time-scale separation to eliminate fast variables and then constructing an effective model from the slow modes. We analyse this effective model and show that the predictions for the probability of fixation of the alleles and the mean time to fixation agree well with those found from numerical simulations of the original model. Contribution to the Focus Issue Evolutionary Modeling and Experimental Evolution edited by José Cuesta, Joachim Krug and Susanna Manrubia.

Thermoelectric properties of pressure-sintered Si(0.8)Ge(0.2) thermoelectric alloys

NASA Technical Reports Server (NTRS)

Vining, Cronin B.; Laskow, William; Hanson, Jack O.; Van Der Beck, Roland R.; Gorsuch, Paul D.

1991-01-01

The thermoelectric properties of 28 sintered Si(0.8)Ge(0.2) alloys, heavily doped with either B or P and prepared from powders with median particle sizes ranging from about 1 to over 100 microns, have been determined from 300 to 1300 K. The thermal conductivity decreases with decreasing particle size; however, the figure of merit is not significantly increased due to a compensating reduction in the electrical conductivity. The thermoelectric figure of merit is in good agreement with results of Dismukes et al. (1964) on similarly doped alloys prepared by zone-leveling techniques. The electrical and thermal conductivity are found to be sensitive to preparation procedure while the Seebeck coefficient and figure of merit are much less sensitive. The high-temperature electrical properties are consistent with charge carrier scattering by acoustic or optical phonons.

MIRAP, microcomputer reliability analysis program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jehee, J.N.T.

1989-01-01

A program for a microcomputer is outlined that can determine minimal cut sets from a specified fault tree logic. The speed and memory limitations of the microcomputers on which the program is implemented (Atari ST and IBM) are addressed by reducing the fault tree's size and by storing the cut set data on disk. Extensive well proven fault tree restructuring techniques, such as the identification of sibling events and of independent gate events, reduces the fault tree's size but does not alter its logic. New methods are used for the Boolean reduction of the fault tree logic. Special criteria formore » combining events in the 'AND' and 'OR' logic avoid the creation of many subsuming cut sets which all would cancel out due to existing cut sets. Figures and tables illustrates these methods. 4 refs., 5 tabs.« less

Researcher Perspectives on Class Size Reduction

ERIC Educational Resources Information Center

Graue, Elizabeth; Rauscher, Erica

2009-01-01

This article applies to class size research Grant and Graue's (1999) position that reviews of research represent conversations in the academic community. By extending our understanding of the class size reduction conversation beyond published literature to the perspectives of researchers who have studied the topic, we create a review that includes…

Analysis of dual-frequency MEMS antenna using H-MRTD method

NASA Astrophysics Data System (ADS)

Yu, Wenge; Zhong, Xianxin; Chen, Yu; Wu, Zhengzhong

2004-10-01

For applying micro/nano technologies and Micro-Electro-Mechanical System (MEMS) technologies in the Radio Frequency (RF) field to manufacture miniature microstrip antennas. A novel MEMS dual-band patch antenna designed using slot-loaded and short-circuited size-reduction techniques is presented in this paper. By controlling the short-plane width, the two resonant frequencies, f10 and f30, can be significantly reduced and the frequency ratio (f30/f10) is tunable in the range 1.7~2.3. The Haar-Wavelet-Based multiresolution time domain (H-MRTD) with compactly supported scaling function for a full three-dimensional (3-D) wave to Yee's staggered cell is used for modeling and analyzing the antenna for the first time. Associated with practical model, an uniaxial perfectly matched layer (UPML) absorbing boundary conditions was developed, In addition , extending the mathematical formulae to an inhomogenous media. Numerical simulation results are compared with those using the conventional 3-D finite-difference time-domain (FDTD) method and measured. It has been demonstrated that, with this technique, space discretization with only a few cells per wavelength gives accurate results, leading to a reduction of both memory requirement and computation time.

THz-driven zero-slippage IFEL scheme for phase space manipulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curry, E.; Fabbri, S.; Musumeci, P.

In this paper, we describe an inverse free electron laser (IFEL) interaction driven by a near single-cycle THz pulse that is group velocity-matched to an electron bunch inside a waveguide, allowing for a sustained interaction in a magnetic undulator. We discuss the application of this guided-THz IFEL technique for compression of a relativistic electron bunch and synchronization with the external laser pulse used to generate the THz pulse via optical rectification, as well as a laser-driven THz streaking diagnostic with the potential for femtosecond scale temporal resolution. Initial measurements of the THz waveform via an electro-optic sampling based technique confirm the predicted reduction of the group velocity, using a curved parallel plate waveguide, as a function of the varying aperture size of the guide. We also present the design of a proof-of-principle experiment based on the bunch parameters available at the UCLA PEGASUS laboratory. With amore » $$10\\,\\mathrm{MV}\\,{{\\rm{m}}}^{-1}$$ THz peak field, our simulation model predicts compression of a $$6\\,\\mathrm{MeV}$$ $$100\\,\\mathrm{fs}$$ electron beam by nearly an order of magnitude and a significant reduction of its initial timing jitter.« less

THz-driven zero-slippage IFEL scheme for phase space manipulation

DOE PAGES

Curry, E.; Fabbri, S.; Musumeci, P.; ...

2016-11-24

In this paper, we describe an inverse free electron laser (IFEL) interaction driven by a near single-cycle THz pulse that is group velocity-matched to an electron bunch inside a waveguide, allowing for a sustained interaction in a magnetic undulator. We discuss the application of this guided-THz IFEL technique for compression of a relativistic electron bunch and synchronization with the external laser pulse used to generate the THz pulse via optical rectification, as well as a laser-driven THz streaking diagnostic with the potential for femtosecond scale temporal resolution. Initial measurements of the THz waveform via an electro-optic sampling based technique confirm the predicted reduction of the group velocity, using a curved parallel plate waveguide, as a function of the varying aperture size of the guide. We also present the design of a proof-of-principle experiment based on the bunch parameters available at the UCLA PEGASUS laboratory. With amore » $$10\\,\\mathrm{MV}\\,{{\\rm{m}}}^{-1}$$ THz peak field, our simulation model predicts compression of a $$6\\,\\mathrm{MeV}$$ $$100\\,\\mathrm{fs}$$ electron beam by nearly an order of magnitude and a significant reduction of its initial timing jitter.« less

Tuning electronic properties by oxidation-reduction reactions at graphene-ruthenium interface

DOE PAGES

Kandyba, Viktor; Al-Mahboob, Abdullah; Giampietri, Alessio; ...

2018-06-06

Mass production of graphene is associated with the growth on catalysts used also in other chemical reactions. In this study, we exploit the oxidation-reduction to tailor the properties of single layer graphene domains with incorporated bi-layer patches on ruthenium. Using photoelectron spectromicroscopy techniques, we find that oxygen, intercalating under single layer and making it p-doped by the formation of Ru-O x, does not intercalate under the bilayer patches with n-doped upper layer, but decorates them under single layer surrounding creating lateral p-n junctions with chemical potential difference of 1.2 eV. O-reduction by thermal treatment in vacuum results in C-vacancy defectsmore » enhancing electronic coupling of remained graphene to Ru, whereas in H 2, vacancy formation is suppressed. Also, for the domains below 15–25 μm size, after O-reduction in H 2, graphene/Ru coupling is restored, while wrinkle pattern produced by O-intercalation is irreversible and can trap reaction products between the wrinkles and Ru surface step edges. In fact, in certain regions of bigger domains, the products, containing H 2O and/or its fragments, remain at the interface, making graphene decoupled and undoped.« less

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

USGS Publications Warehouse

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.; Zawislanski, P.T.

1999-01-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are needed to confirm this preliminary assessment. We have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields ??0.2??? precision on 80Se/76Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 ??g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.

1999-09-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. The authors report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are neededmore » to confirm this preliminary assessment. The authors have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields {+-}0.2% precision on {sup 80}Se/{sup 76}Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 {micro}g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.« less

Blob-enhanced reconstruction technique

NASA Astrophysics Data System (ADS)

Castrillo, Giusy; Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso

2016-09-01

A method to enhance the quality of the tomographic reconstruction and, consequently, the 3D velocity measurement accuracy, is presented. The technique is based on integrating information on the objects to be reconstructed within the algebraic reconstruction process. A first guess intensity distribution is produced with a standard algebraic method, then the distribution is rebuilt as a sum of Gaussian blobs, based on location, intensity and size of agglomerates of light intensity surrounding local maxima. The blobs substitution regularizes the particle shape allowing a reduction of the particles discretization errors and of their elongation in the depth direction. The performances of the blob-enhanced reconstruction technique (BERT) are assessed with a 3D synthetic experiment. The results have been compared with those obtained by applying the standard camera simultaneous multiplicative reconstruction technique (CSMART) to the same volume. Several blob-enhanced reconstruction processes, both substituting the blobs at the end of the CSMART algorithm and during the iterations (i.e. using the blob-enhanced reconstruction as predictor for the following iterations), have been tested. The results confirm the enhancement in the velocity measurements accuracy, demonstrating a reduction of the bias error due to the ghost particles. The improvement is more remarkable at the largest tested seeding densities. Additionally, using the blobs distributions as a predictor enables further improvement of the convergence of the reconstruction algorithm, with the improvement being more considerable when substituting the blobs more than once during the process. The BERT process is also applied to multi resolution (MR) CSMART reconstructions, permitting simultaneously to achieve remarkable improvements in the flow field measurements and to benefit from the reduction in computational time due to the MR approach. Finally, BERT is also tested on experimental data, obtaining an increase of the signal-to-noise ratio in the reconstructed flow field and a higher value of the correlation factor in the velocity measurements with respect to the volume to which the particles are not replaced.

SU-E-I-37: Low-Dose Real-Time Region-Of-Interest X-Ray Fluoroscopic Imaging with a GPU-Accelerated Spatially Different Bilateral Filtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, H; Lee, J; Pua, R

2014-06-01

Purpose: The purpose of our study is to reduce imaging radiation dose while maintaining image quality of region of interest (ROI) in X-ray fluoroscopy. A low-dose real-time ROI fluoroscopic imaging technique which includes graphics-processing-unit- (GPU-) accelerated image processing for brightness compensation and noise filtering was developed in this study. Methods: In our ROI fluoroscopic imaging, a copper filter is placed in front of the X-ray tube. The filter contains a round aperture to reduce radiation dose to outside of the aperture. To equalize the brightness difference between inner and outer ROI regions, brightness compensation was performed by use of amore » simple weighting method that applies selectively to the inner ROI, the outer ROI, and the boundary zone. A bilateral filtering was applied to the images to reduce relatively high noise in the outer ROI images. To speed up the calculation of our technique for real-time application, the GPU-acceleration was applied to the image processing algorithm. We performed a dosimetric measurement using an ion-chamber dosimeter to evaluate the amount of radiation dose reduction. The reduction of calculation time compared to a CPU-only computation was also measured, and the assessment of image quality in terms of image noise and spatial resolution was conducted. Results: More than 80% of dose was reduced by use of the ROI filter. The reduction rate depended on the thickness of the filter and the size of ROI aperture. The image noise outside the ROI was remarkably reduced by the bilateral filtering technique. The computation time for processing each frame image was reduced from 3.43 seconds with single CPU to 9.85 milliseconds with GPU-acceleration. Conclusion: The proposed technique for X-ray fluoroscopy can substantially reduce imaging radiation dose to the patient while maintaining image quality particularly in the ROI region in real-time.« less

An Event-Triggered Machine Learning Approach for Accelerometer-Based Fall Detection.

PubMed

Putra, I Putu Edy Suardiyana; Brusey, James; Gaura, Elena; Vesilo, Rein

2017-12-22

The fixed-size non-overlapping sliding window (FNSW) and fixed-size overlapping sliding window (FOSW) approaches are the most commonly used data-segmentation techniques in machine learning-based fall detection using accelerometer sensors. However, these techniques do not segment by fall stages (pre-impact, impact, and post-impact) and thus useful information is lost, which may reduce the detection rate of the classifier. Aligning the segment with the fall stage is difficult, as the segment size varies. We propose an event-triggered machine learning (EvenT-ML) approach that aligns each fall stage so that the characteristic features of the fall stages are more easily recognized. To evaluate our approach, two publicly accessible datasets were used. Classification and regression tree (CART), k -nearest neighbor ( k -NN), logistic regression (LR), and the support vector machine (SVM) were used to train the classifiers. EvenT-ML gives classifier F-scores of 98% for a chest-worn sensor and 92% for a waist-worn sensor, and significantly reduces the computational cost compared with the FNSW- and FOSW-based approaches, with reductions of up to 8-fold and 78-fold, respectively. EvenT-ML achieves a significantly better F-score than existing fall detection approaches. These results indicate that aligning feature segments with fall stages significantly increases the detection rate and reduces the computational cost.

Sample size and power calculations for detecting changes in malaria transmission using antibody seroconversion rate.

PubMed

Sepúlveda, Nuno; Paulino, Carlos Daniel; Drakeley, Chris

2015-12-30

Several studies have highlighted the use of serological data in detecting a reduction in malaria transmission intensity. These studies have typically used serology as an adjunct measure and no formal examination of sample size calculations for this approach has been conducted. A sample size calculator is proposed for cross-sectional surveys using data simulation from a reverse catalytic model assuming a reduction in seroconversion rate (SCR) at a given change point before sampling. This calculator is based on logistic approximations for the underlying power curves to detect a reduction in SCR in relation to the hypothesis of a stable SCR for the same data. Sample sizes are illustrated for a hypothetical cross-sectional survey from an African population assuming a known or unknown change point. Overall, data simulation demonstrates that power is strongly affected by assuming a known or unknown change point. Small sample sizes are sufficient to detect strong reductions in SCR, but invariantly lead to poor precision of estimates for current SCR. In this situation, sample size is better determined by controlling the precision of SCR estimates. Conversely larger sample sizes are required for detecting more subtle reductions in malaria transmission but those invariantly increase precision whilst reducing putative estimation bias. The proposed sample size calculator, although based on data simulation, shows promise of being easily applicable to a range of populations and survey types. Since the change point is a major source of uncertainty, obtaining or assuming prior information about this parameter might reduce both the sample size and the chance of generating biased SCR estimates.

Observation of martensitic transformation in Ni50Mn41Cu4Sn5 Heusler alloy prepared by mechanical alloying

NASA Astrophysics Data System (ADS)

Saini, Dinesh; Singh, Satyavir; Banerjee, M. K.; Sachdev, K.

2017-05-01

Mechanical alloying route has been employed for preparation of a single phase Ni50Mn41Cu4Sn5 (atomic %) Heusler alloy. Use of high energy planetary ball mill enables successful preparation of the same as authenticated by detailed X-ray diffraction (XRD) study. Microstructural study is carried out by optical and scanning electron microscopic techniques. XRD results reveal that increasing milling time leads to reduction in crystallite size and concurrent increase in lattice strain. Microstructural results indicate formation of self-assembled martensite twins.

Sandwich Structure Risk Reduction in Support of the Payload Adapter Fitting

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Jackson, J. R.; Guin, W. E.

2018-01-01

Reducing risk for utilizing honeycomb sandwich structure for the Space Launch System payload adapter fitting includes determining what parameters need to be tested for damage tolerance to ensure a safe structure. Specimen size and boundary conditions are the most practical parameters to use in damage tolerance inspection. The effect of impact over core splices and foreign object debris between the facesheet and core is assessed. Effects of enhanced damage tolerance by applying an outer layer of carbon fiber woven cloth is examined. A simple repair technique for barely visible impact damage that restores all compression strength is presented.

Economic choice for hardwood sawmill operations (ECHO)

Treesearch

P.H. Steele; Philip A. Araman; C. Boden

2002-01-01

Reductions in sawkerf on headrigs and resaws can dramatically increase lumber recovery. Research has also shown that lumber target size reductions are even more important than kerf reductions in providing increased lumber recovery. Decreases in either sawkerf or lumber size, however, always come at some cost in both capital and variable costs. Determining whether the...

Influence of TiO2 hollow sphere size on its photo-reduction activity for toxic Cr(VI) removal.

PubMed

Cai, Jiabai; Wu, Xueqing; Zheng, Fengying; Li, Shunxing; Wu, Yaling; Lin, Yanping; Lin, Liting; Liu, Biwen; Chen, Qiaoying; Lin, Luxiu

2017-03-15

After polystyrene@titanium dioxide (PS@TiO 2 ) composite with different size was calcined at designated temperature, TiO 2 hollow sphere with controllable size was obtained for high efficient photo-reduction of Cr(VI). The feature of the TiO 2 hollow sphere was investigated by SEM, TEM, XRD, UV-Vis, and photoluminescence. The photo-reduction of Cr(VI) were measured for the performance assessment of the TiO 2 hollow sphere, Cr(VI) was used as an electron acceptor. After irradiation for 2h, the photo-reduction rate of Cr(VI) (pH=2.82) for TiO 2 (450nm) was 96%, which exhibited an increase of 5% and 8% compared with TiO 2 (370nm) and TiO 2 (600nm). The absorption edges of TiO 2 hollow sphere (450nm) was largest with the increasing of hollow sphere size from 370 to 600nm. The optimal hollow sphere size of TiO 2 was 450nm for the photo-reduction of Cr(VI), because the light-harvesting efficiency (the best of absorption edge) and photo-generated electron-hole separation rate (the best of photo-reduction rate) of TiO 2 hollow sphere were controlled by its hollow sphere size. In addition, we find that the behavior of the hydrogen production was inhibited by the coexistence Cr(VI) solution. This study can improve our understanding of the mechanism for the activity enhancement by the optimal hollow sphere size of TiO 2 . Copyright © 2016 Elsevier Inc. All rights reserved.

Thermodynamic changes in mechanochemically synthesized magnesium hydride nanoparticles.

PubMed

Paskevicius, Mark; Sheppard, Drew A; Buckley, Craig E

2010-04-14

The thermodynamic properties of magnesium hydride nanoparticles have been investigated by hydrogen decomposition pressure measurements using the Sieverts technique. A mechanochemical method was used to synthesize MgH(2) nanoparticles (down to approximately 7 nm in size) embedded in a LiCl salt matrix. In comparison to bulk MgH(2), the mechanochemically produced MgH(2) with the smallest particle size showed a small but measurable decrease in the decomposition reaction enthalpy (DeltaH decrease of 2.84 kJ/mol H(2) from DeltaH(bulk) = 74.06 +/- 0.42 kJ/mol H(2) to DeltaH(nano) = 71.22 +/- 0.49 kJ/mol H(2)). The reduction in DeltaH matches theoretical predictions and was also coupled with a similar reduction in reaction entropy (DeltaS decrease of 3.8 J/mol H(2)/K from DeltaS(bulk) = 133.4 +/- 0.7 J/mol H(2)/K to DeltaS(nano) = 129.6 +/- 0.8 J/mol H(2)/K). The thermodynamic changes in the MgH(2) nanoparticle system correspond to a drop in the 1 bar hydrogen equilibrium temperature (T(1 bar)) by approximately 6 degrees C to 276.2 +/- 2.4 degrees C in contrast to the bulk MgH(2) system at 281.8 +/- 2.2 degrees C. The reduction in the desorption temperature is less than that expected from theoretical studies due to the decrease in DeltaS that acts to partially counteract the effect from the change in DeltaH.

Biofuel manufacturing from woody biomass: effects of sieve size used in biomass size reduction.

PubMed

Zhang, Meng; Song, Xiaoxu; Deines, T W; Pei, Z J; Wang, Donghai

2012-01-01

Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes.

Nickel-doped cobalt ferrite nanoparticles: efficient catalysts for the reduction of nitroaromatic compounds and photo-oxidative degradation of toxic dyes

NASA Astrophysics Data System (ADS)

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-06-01

This study deals with the exploration of NixCo1-xFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co0.4Ni0.6Fe2O4 (154.02 m2 g-1). Co0.4Ni0.6Fe2O4 showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe2O4 was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH4 on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni2+ in to the cobalt ferrite lattice due to octahedral site preference of Ni2+. Almost 99% degradation was achieved in 20 min using NiFe2O4 nanoparticles as catalyst.

Labia Minora, Labia Majora, and Clitoral Hood Alteration: Experience-Based Recommendations.

PubMed

Hunter, John G

2016-01-01

Aesthetic alteration of the genitalia is increasingly sought by women unhappy with the size, shape, and appearance of their vulva. Although the labia minora are usually the focus of concern, the entire anatomic region--minora, labia majora, clitoral hood, perineum, and mons pubis--should be evaluated in a preoperative assessment of women seeking labiaplasty. Labiaplasty is associated with high patient satisfaction and low complication rates. The three basic labia minora reduction techniques--edge excision, wedge excision, and central deepithelialization--as well as their advantages and disadvantages are discussed to assist the surgeon in tailoring technique selection to individual genital anatomy and aesthetic desires. We present key points of the preoperative anatomic evaluation, technique selection, operative risks, perioperative care, and potential complications for labia minora, labia majora, and clitoral hood alterations, based on a large operative experience. Labiaplasty competency should be part of the skill set of all plastic surgeons. © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Modified Activation Technique for Nasal Stent of Nasoalveolar Molding Appliance for Columellar Lengthening in Bilateral Cleft Lip/Palate.

PubMed

Patil, Pravinkumar G; Nimbalkar-Patil, Smita P

2018-01-01

Bilateral cleft lip/cleft palate is associated with nasal deformities typified by a short columella. The presurgical nasoalveolar molding (NAM) therapy approach includes reduction of the size of the intraoral alveolar cleft as well as positioning of the surrounding deformed soft tissues and cartilages. In a bilateral cleft patient, NAM, along with columellar elongation, eliminates the need for columellar lengthening surgery. Thus the frequent surgical intervention to achieve the desired esthetic results can be avoided. This article proposes a modified activation technique of the nasal stent for a NAM appliance for columellar lengthening in bilateral cleft lip/palate patients. The design highlights relining of the columellar portion of the nasal stent and the wire-bending of the nasal stent to achieve desirable results within the limited span of plasticity of the nasal cartilages. With this technique the vertical taping of the premaxilla to the oral plate can be avoided. © 2016 by the American College of Prosthodontists.

Completion of Gamma Knife radiosurgery for AVM treatment after unplanned interruption-technical note.

PubMed

Raman, Hari S; Santanam, Lakshmi; Vellimana, Ananth K; Drzymala, Robert E; Tsien, Christina I; Zipfel, Gregory J

2018-02-17

Gamma Knife radiosurgery is an established technique for non-urgent treatment of various intracranial pathologies. Intra-procedural dislodgement of the stereotactic frame is an uncommon occurrence that could lead to abortion of ongoing treatment and necessitate more invasive treatment strategies. In this case report, we describe a novel method for resumption of Gamma Knife treatment after an unplanned intra-procedural interruption. The case example involves a radiosurgical treatment of a Spetzler-Martin grade I arteriovenous malformation. Our technique involves integration of scans and coordinate systems from two imaging sessions using the composite isodose line to resolve translational differences, thereby limiting delivery of remaining shots to the untreated region of the lesion. MRI follow-up at 13 months showed a reduction in the nidus size with no evidence of any radiation injury to the surrounding brain parenchyma. We believe this technique will allow care teams to effectively salvage interrupted Gamma Knife procedures and reduce progression to more invasive treatment options.

Macromolecular structural changes in bituminous coals during extraction and solubilization. Annual technical progress report, September 1, 1980-August 31, 1981

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peppas, N.A.; Hill-Lievense, M.E.; Hooker, D.T. II

1981-01-01

Seven coal samples ranging from a lignite with 69.95% carbon to an anthracite with 94.17% carbon on a dry mineral matter-free (dmmf) basis were extracted with pyridine at its reflux temperature for two weeks. The coal matrices obtained were subjected to two degradation techniques, the Sternberg reductive alkylation technique and the Miyake alkylation technique. Gel permeation chromatographic analysis of pyridine-extracted liquids of the alkylated coal showed average molecular weights smaller than those of the original coal extracts. Electron impact mass spectrometry was used to obtain the mass spectra of these alkylated coal samples. Based on investigation of the recurring patternmore » of the peaks of the mass spectra of these products it was concluded that a cluster size of 126 to 130 is characteristic of the crosslinked structure of the coal studied. In addition, several chemical compounds in the range of m/e 78-191 were identified.« less

Does changing social influence engender changes in alcohol intake? A meta-analysis.

PubMed

Prestwich, Andrew; Kellar, Ian; Conner, Mark; Lawton, Rebecca; Gardner, Peter; Turgut, Liz

2016-10-01

Past research has suggested that social influences on drinking can be manipulated with subsequent reductions in alcohol intake. However, the experimental evidence for this and the best strategies to positively change these social influences have not been meta-analyzed. This research addressed these gaps. Randomized controlled trials testing social influence-based interventions on adults' drinking were systematically reviewed and meta-analyzed. The behavior change techniques used in each study were coded and the effect sizes showing the impact of each intervention on (a) social influence and (b) alcohol intake were calculated. Metaregressions identified the association between these effect sizes, as well as the effect of specific behavior change techniques on social influences. Forty-one studies comprising 17,445 participants were included. Changes in social influences were significantly associated with changes in alcohol intake. However, even moderate-to-large changes in social influences corresponded with only a small change in drinking behavior and changing social influences did not reduce alcohol-related problems. Providing normative information about others' behavior and experiences was the most effective technique to change social influences. Social influences and normative beliefs can be changed in drinkers, particularly by providing normative information about how much others' drink. However, even generating large changes in these constructs are likely to engender only small changes in alcohol intake. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Dynamic response of RC beams strengthened with near surface mounted Carbon-FRP rods subjected to damage

NASA Astrophysics Data System (ADS)

Capozucca, R.; Blasi, M. G.; Corina, V.

2015-07-01

Near surface mounted (NSM) technique with fiber reinforced polymer (FRP) is becoming a common method in the strengthening of concrete beams. The availability of NSM FRP technique depends on many factors linked to materials and geometry - dimensions of the rods used, type of FRP material employed, rods’ surface configuration, groove size - and to adhesion between concrete and FRP rods. In this paper detection of damage is investigated measuring the natural frequency values of beam in the case of free-free ends. Damage was due both to reduction of adhesion between concrete and carbon-FRP rectangular and circular rods and cracking of concrete under static bending tests on beams. Comparison between experimental and theoretical frequency values evaluating frequency changes due to damage permits to monitor actual behaviour of RC beams strengthened by NSM CFRP rods.

An improved technique for the 2H/1H analysis of urines from diabetic volunteers

USGS Publications Warehouse

Coplen, T.B.; Harper, I.T.

1994-01-01

The H2-H2O ambient-temperature equilibration technique for the determination of 2H/1H ratios in urinary waters from diabetic subjects provides improved accuracy over the conventional Zn reduction technique. The standard deviation, ~ 1-2???, is at least a factor of three better than that of the Zn reduction technique on urinary waters from diabetic volunteers. Experiments with pure water and solutions containing glucose, urea and albumen indicate that there is no measurable bias in the hydrogen equilibration technique.The H2-H2O ambient-temperature equilibration technique for the determination of 2H/1H ratios in urinary waters from diabetic subjects provides improved accuracy over the conventional Zn reduction technique. The standard deviation, approximately 1-2%, is at least a factor of three better than that of the Zn reduction technique on urinary waters from diabetic volunteers. Experiments with pure water and solutions containing glucose, urea and albumen indicate that there is no measurable bias in the hydrogen equilibration technique.

Effects of double ligation of Stensen's duct on the rabbit parotid gland.

PubMed

Maria, O M; Maria, S M; Redman, R S; Maria, A M; Saad El-Din, T A; Soussa, E F; Tran, S D

2014-04-01

Salivary gland duct ligation is an alternative to gland excision for treating sialorrhea or reducing salivary gland size prior to tumor excision. Duct ligation also is used as an approach to study salivary gland aging, regeneration, radiotherapy, sialolithiasis and sialadenitis. Reports conflict about the contribution of each salivary cell population to gland size reduction after ductal ligation. Certain cell populations, especially acini, reportedly undergo atrophy, apoptosis and proliferation during reduction of gland size. Acini also have been reported to de-differentiate into ducts. These contradictory results have been attributed to different animal or salivary gland models, or to methods of ligation. We report here a bilateral double ligature technique for rabbit parotid glands with histologic observations at 1, 7, 14, 30, 60 days after ligation. A large battery of special stains and immunohistochemical procedures was employed to define the cell populations. Four stages with overlapping features were observed that led to progressive shutdown of gland activities: 1) marked atrophy of the acinar cells occurred by 14 days, 2) response to and removal of the secretory material trapped in the acinar and ductal lumens mainly between 30 and 60 days, 3) reduction in the number of parenchymal (mostly acinar) cells by apoptosis that occurred mainly between 14-30 days, and 4) maintenance of steady-state at 60 days with a low rate of fluid, protein, and glycoprotein secretion, which greatly decreased the number of leukocytes engaged in the removal of the luminal contents. The main post- ligation characteristics were dilation of ductal and acinar lumens, massive transient infiltration of mostly heterophils (rabbit polymorphonuclear leukocytes), acinar atrophy, and apoptosis of both acinar and ductal cells. Proliferation was uncommon except in the larger ducts. By 30 days, the distribution of myoepithelial cells had spread from exclusively investing the intercalated ducts pre-ligation to surrounding a majority of the residual duct-like structures, many of which clearly were atrophic acini. Thus, both atrophy and apoptosis made major contributions to the post-ligation reduction in gland size. Structures also occurred with both ductal and acinar markers that suggested acini differentiating into ducts. Overall, the reaction to duct ligation proceeded at a considerably slower pace in the rabbit parotid glands than has been reported for the salivary glands of the rat.

Structural Health Monitoring of Large Structures

NASA Technical Reports Server (NTRS)

Kim, Hyoung M.; Bartkowicz, Theodore J.; Smith, Suzanne Weaver; Zimmerman, David C.

1994-01-01

This paper describes a damage detection and health monitoring method that was developed for large space structures using on-orbit modal identification. After evaluating several existing model refinement and model reduction/expansion techniques, a new approach was developed to identify the location and extent of structural damage with a limited number of measurements. A general area of structural damage is first identified and, subsequently, a specific damaged structural component is located. This approach takes advantage of two different model refinement methods (optimal-update and design sensitivity) and two different model size matching methods (model reduction and eigenvector expansion). Performance of the proposed damage detection approach was demonstrated with test data from two different laboratory truss structures. This space technology can also be applied to structural inspection of aircraft, offshore platforms, oil tankers, ridges, and buildings. In addition, its applications to model refinement will improve the design of structural systems such as automobiles and electronic packaging.

Fabrication of micron scale metallic structures on photo paper substrates by low temperature photolithography for device applications

NASA Astrophysics Data System (ADS)

Cooke, M. D.; Wood, D.

2015-11-01

Using commercial standard paper as a substrate has a significant cost reduction implication over other more expensive substrate materials by approximately a factor of 100 (Shenton et al 2015 EMRS Spring Meeting; Zheng et al 2013 Nat. Sci. Rep. 3 1786). Discussed here is a novel process which allows photolithography and etching of simple metal films deposited on paper substrates, but requires no additional facilities to achieve it. This allows a significant reduction in feature size down to the micron scale over devices made using more conventional printing solutions which are of the order of tens of microns. The technique has great potential for making cheap disposable devices with additional functionality, which could include flexibility and foldability, simple disposability, porosity and low weight requirements. The potential for commercial applications and scale up is also discussed.

Electrohydrodynamic convective heat transfer in a square duct.

PubMed

Grassi, Walter; Testi, Daniele

2009-04-01

Laminar to weakly turbulent forced convection in a square duct heated from the bottom is strengthened by ion injection from an array of high-voltage points opposite the heated strip. Both positive and negative ion injection are activated within the working liquid HFE-7100 (C(4)F(9)OCH(3)), with transiting electrical currents on the order of 0.1 mA. Local temperatures on the heated wall are measured by liquid crystal thermography. The tests are conducted in a Reynolds number range from 510 to 12,100. In any case, heat transfer is dramatically augmented, almost independently from the flow rate. The pressure drop increase caused by the electrohydrodynamically induced flow is also measured. A profitable implementation of the technique in the design of heat sinks and heat exchangers is foreseen; possible benefits are pumping power reduction, size reduction, and heat exchange capability augmentation.

Primary obstructive megaureter.

PubMed

Sripathi, V; King, P A; Thomson, M R; Bogle, M S

1991-07-01

Twenty-three children with primary obstructive megaureters presented between 1978 and 1988 to the Princess Margaret Hospital for Children in Perth. Twenty-eight ureters were treated. Urinary infections were the presenting feature in 14 children. The obstructive segment was transvesically excised. Histopathologic examination of the distal, intramural ureter showed fibromuscular disarray with a relative increase in fibrous tissue and reduction of musculature in all specimens. Twenty-two ureters were tapered by excision and all 28 were reimplanted using an antireflux technique. Seventeen children were followed for an average of 3 years. Seven children showed renal growth, reduction in ureteric size by greater than 2 cm, improvement in glomerular filtration rate by more than 10%, no obstruction on reflux, and no infections in postoperative period. Four children showed all the above but suffered one or more infections after the operation. Of the remaining 6 children, 3 had postoperative obstruction and 3 had vesicoureteric reflux.

Effects of hypokinesia and hypodynamia upon protein turnover in hindlimb muscles of the rat

NASA Technical Reports Server (NTRS)

Loughna, Paul T.; Goldspink, David F.; Goldspink, Geoffrey

1987-01-01

Hypokinesia/hypodynamia was induced in the hindlimb muscles of the rat, using a suspension technique. This caused differing degrees of atrophy in different muscles. However, this atrophy was reduced in muscles held in a lenghthened position. The greatest degree of wasting was observed in the unstretched soleus, a slow postural muscle, where both Type 1 and Type 2a fibers atrophied to the same degree. However, wasting of the gastrocnemius muscle was associated with a reduction in the size of the Type 2b fibers. In both slow-postural and fast-phasic hindlimb muscles, atrophy was brought about by a reduction in the rate of protein synthesis in conjunction with an elevation in the rate of protein degradation. When inactive muscles were passively stretched, both protein synthesis and degradation were dramatically elevated. Even periods of stretch of as little as 0.5 h/d were found to significantly decrease atrophy in inactive muscles.

Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

NASA Astrophysics Data System (ADS)

Kothari, Kunal B.

Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron-sized titanium aluminide powders were rapidly consolidated to form near-net shape titanium aluminide parts in form of small discs and tiles. The rapidly consolidated titanium aluminide parts were found to be fully dense. The microstructure morphology was found to vary with consolidation conditions. The mechanical properties were found to be significantly dependent on microstructure morphology and grain size. Due to rapid consolidation, grain growth during consolidation was limited, which in turn led to enhanced mechanical properties. The high temperature mechanical properties for the consolidated titanium aluminide samples were characterized and were found to retain good mechanical performance up to 700°C. Micron-sized titanium aluminide powders with slightly less Aluminum and small Nb, and Cr additions were rapidly consolidated into near-net shape parts. The consolidated parts were found to exhibit enhanced mechanical performance in terms of ductility and yield strength. The negative effect of Oxygen on the flexural strength at high temperatures was found to be reduced with the addition of Nb. In an effort to further reduce the grain size of the consolidated titanium aluminide samples, the as-received titanium aluminide powders were milled in an attrition mill. The average powder particle size of the powders was reduced by 60% after milling. The milled powders were then rapidly consolidated. The grain size of the consolidated parts was found to be in the sub-micrometer range. The mechanical properties were found to be significantly enhanced due to reduction of grain size in the sub-micrometer range. In order to develop a metal matrix composite based on titanium aluminide matrix reinforced with titanium boride, an experiment to study the effect of rapid consolidation on titanium diboride powders was conducted. Micron-sized titanium diboride powders were consolidated and were found to be 93% dense and exhibited minimal grain growth. The low density of the consolidated part was attributed to low consolidation temperature. Titanium aluminide and titanium diboride powders were blended together in an attrition mill and rapidly consolidated. A metal matrix composite with titanium aluminide matrix reinforced with titanium monoboride plates was formed. The titanium diboride in the powder form was found to be transformed to titanium monoboroide plates during consolidation due to the thermodynamic equilibrium between titanium and titanium monoboride. The metal matrix composite was found to be 90% dense. The low density was due to particle size mismatch between the matrix and reinforcement powders and low consolidation temperature. An increase in the volume of titanium monoboride plates in the metal matrix composite was accompanied by an increase in the elastic modulus of the metal matrix composite.

Electrodeposition of nano-sized bismuth on copper foil as electrocatalyst for reduction of CO2 to formate

NASA Astrophysics Data System (ADS)

Lv, Weixin; Zhou, Jing; Bei, Jingjing; Zhang, Rui; Wang, Lei; Xu, Qi; Wang, Wei

2017-01-01

Electrochemical reduction of carbon dioxide (CO2) to formate is energetically inefficient because high overpotential is required for reduction of CO2 to formate on most traditional catalysts. In this paper, a novel nano-sized Bi-based electrocatalyst deposited on a Cu foil has been synthesized, which can be used as a cathode for electrochemical reduction of CO2 to formate with a low overpotential (0.69 V) and a high selectivity (91.3%). The electrocatalyst can show excellent catalytic performance toward reduction of CO2 which can probably be attributed to the nano-sized structure and the surface oxide layer. The energy efficiency for reduction of CO2 to formate can reach to 50% when an IrxSnyRuzO2/Ti electrode is used as anode, it is one of the highest values found in the literatures and very practicable for sustainable fuel synthesis.

Simultaneous Comparison of Two Roller Compaction Techniques and Two Particle Size Analysis Methods.

PubMed

Saarinen, Tuomas; Antikainen, Osmo; Yliruusi, Jouko

2017-11-01

A new dry granulation technique, gas-assisted roller compaction (GARC), was compared with conventional roller compaction (CRC) by manufacturing 34 granulation batches. The process variables studied were roll pressure, roll speed, and sieve size of the conical mill. The main quality attributes measured were granule size and flow characteristics. Within granulations also the real applicability of two particle size analysis techniques, sieve analysis (SA) and fast imaging technique (Flashsizer, FS), was tested. All granules obtained were acceptable. In general, the particle size of GARC granules was slightly larger than that of CRC granules. In addition, the GARC granules had better flowability. For example, the tablet weight variation of GARC granules was close to 2%, indicating good flowing and packing characteristics. The comparison of the two particle size analysis techniques showed that SA was more accurate in determining wide and bimodal size distributions while FS showed narrower and mono-modal distributions. However, both techniques gave good estimates for mean granule sizes. Overall, SA was a time-consuming but accurate technique that provided reliable information for the entire granule size distribution. By contrast, FS oversimplified the shape of the size distribution, but nevertheless yielded acceptable estimates for mean particle size. In general, FS was two to three orders of magnitude faster than SA.

Influence of the size reduction of organic waste on their anaerobic digestion.

PubMed

Palmowski, L M; Müller, J A

2000-01-01

The rate-limiting step in anaerobic digestion of organic solid waste is generally their hydrolysis. A size reduction of the particles and the resulting enlargement of the available specific surface can support the biological process in two ways. Firstly, in case of substrates with a high content of fibres and a low xegradability, their comminution yields to an improved digester gas production. This leads to a decreased amount of residues to be disposed of and to an increased quantity of useful digester gas. The second effect of the particle size reduction observed with all the substrates but particularly with those of low degradability is a reduction of the technical digestion time. Furthermore, the particle size of organic waste has an influence on the dewaterability after codigestion with sewage sludge. The presence of organic waste residues improves the dewaterability measured as specific resistance to filtration but this positive effect is attenuated if the particle size of the solids is reduced.

Technical- and environmental-efficiency analysis of irrigated cotton-cropping systems in Punjab, Pakistan using data envelopment analysis.

PubMed

Ullah, Asmat; Perret, Sylvain R

2014-08-01

Cotton cropping in Pakistan uses substantial quantities of resources and adversely affects the environment with pollutants from the inputs, particularly pesticides. A question remains regarding to what extent the reduction of such environmental impact is possible without compromising the farmers' income. This paper investigates the environmental, technical, and economic performances of selected irrigated cotton-cropping systems in Punjab to quantify the sustainability of cotton farming and reveal options for improvement. Using mostly primary data, our study quantifies the technical, cost, and environmental efficiencies of different farm sizes. A set of indicators has been computed to reflect these three domains of efficiency using the data envelopment analysis technique. The results indicate that farmers are broadly environmentally inefficient; which primarily results from poor technical inefficiency. Based on an improved input mix, the average potential environmental impact reduction for small, medium, and large farms is 9, 13, and 11 %, respectively, without compromising the economic return. Moreover, the differences in technical, cost, and environmental efficiencies between small and medium and small and large farm sizes were statistically significant. The second-stage regression analysis identifies that the entire farm size significantly affects the efficiencies, whereas exposure to extension and training has positive effects, and the sowing methods significantly affect the technical and environmental efficiencies. Paradoxically, the formal education level is determined to affect the efficiencies negatively. This paper discusses policy interventions that can improve the technical efficiency to ultimately increase the environmental efficiency and reduce the farmers' operating costs.

SU-E-J-81: Adaptive Radiotherapy for IMRT Head & Neck Patient in AKUH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yousuf, A; Qureshi, B; Qadir, A

2015-06-15

Purpose: In this study we proposed Adaptive radiotherapy for IMRT patients which will brought an additional dimension to the management of patients with H&N cancer in Aga Khan University Hospital. Methods: In this study 5 Head and Neck (H&N) patients plan where selected, who’s Re-CT were done during the course of their treatment, they were simulated with IMRT technique to learn the consequence of anatomical changes that may occur during the treatment, as they are more dramatic changes can occur as compare to conventional treatment. All the organ at risk were drawn according RTOG guidelines and doses were checked asmore » per NCCN guidelines. Results: The reduction in size of Planning target volume (PTV) is more than 20% in all the cases which leads to 3 to 5 % overdose to normal tissues and Organ at Risk. Conclusion: Through this study we would like to emphasis the importance of Adaptive Radiotherapy practice in all IMRT (H&N) patients, although prospective studies are required with larger sample sizes to address the safety and the clinical effect of such approaches on patient outcome, also one need to develop protocols before implementation of this technique in practice.« less

ECHO: Machine feasibility program

Treesearch

Philip H. Steele; Craig Boden; Philip A. Araman

2000-01-01

Reductions in saw kerf (the term saw kerf refers to both the sawtooth width as well as the actual sawline made in sawing) on headrigs and resaws can dramatically increase lumber recovery. Research has also shown that lumber target size reductions are even more important than kerf reductions in providing increased lumber recovery. Decreases in either kerf or lumber size...

The Nevada Class Size Reduction Evaluation Study, 1995.

ERIC Educational Resources Information Center

Nevada State Dept. of Education, Carson City.

A primary purpose for reducing the student-teacher ratio in the early grades is to make students more successful in their later years. This document contains two separate, but interrelated reports that examined two aspects of the 1989 Class Size Reduction (CSR) Act in Nevada. The Act called for a reduction in student-teacher ratios for selected…

On the thermal stability of physical vapor deposited oxide-hardened nanocrystalline gold thin films

DOE PAGES

Argibay, Nicolas; Mogonye, J. E.; Michael, Joseph R.; ...

2015-04-08

We describe a correlation between electrical resistivity and grain size for PVD synthesized polycrystalline oxide-hardened metal-matrix thin films in oxide-dilute (<5 vol. % oxide phase) compositions. The correlation is based on the Mayadas-Shatzkes (M-S) electron scattering model, predictive of grain size evolution as a function of composition in the oxide-dilute regime for 2 μm thick Au-ZnO films. We describe a technique to investigate grain boundary (GB) mobility and the thermal stability of GBs based on in situelectrical resistivity measurements during annealing experiments, interpreted using a combination of the M-S model and the Michels et al. model describing solute drag stabilizedmore » grain growth kinetics. Using this technique, activation energy and pre-exponential Arrhenius parameter values of E a = 21.6 kJ/mol and A o = 2.3 × 10 -17 m 2/s for Au-1 vol. % ZnO and E a =12.7 kJ/mol and A o = 3.1 × 10 -18 m 2/s for Au-2 vol.% ZnO were determined. In the oxide-dilute regime, the grain size reduction of the Au matrix yielded a maximum hardness of 2.6 GPa for 5 vol. % ZnO. A combined model including percolation behavior and grain refinement is presented that accurately describes the composition dependent change in electrical resistivity throughout the entire composition range for Au-ZnO thin films. As a result, the proposed correlations are supported by microstructural characterization using transmission electron microscopy and electron diffraction mapping for grain size determination.« less

Development, Characterization and Evaluation of Solid Lipid Nanoparticles as a potential Anticancer Drug Delivery System

NASA Astrophysics Data System (ADS)

Patel, Meghavi

Solid lipid nanoparticles (SLNs) consist of spherical solid lipid particles in the nanometer size range, which are dispersed in water or in an aqueous surfactant solution. SLN technology represents a promising new approach to deliver hydrophilic as well as lipophilic drugs. The commercialization of SLN technology remains limited despite numerous efforts from researchers. The purpose of this research was to advance SLN preparation methodology by investigating the feasibility of preparing glyceryl monostearate (GMS) nanoparticles by using three preparation methods namely microemulsion technique, magnetic stirring technique and temperature modulated solidification technique of which the latter two were developed in our laboratory. An anticancer drug 5-fluorouracil was incorporated in the SLNs prepared via the temperature modulated solidification process. Optimization of the magnetic stirring process was performed to evaluate how the physicochemical properties of the SLN was influenced by systematically varying process parameters including concentration of the lipid, concentration of the surfactant, type of surfactant, time of stirring and temperature of storage. The results demonstrated 1:2 GMS to tween 80 ratio, 150 ml dispersion medium and 45 min stirring at 4000 RPM speed provided an optimum formulation via the temperature modulated solidification process. SLN dispersions were lyophilized to stabilize the solid lipid nanoparticles and the lyophilizates exhibited good redispersibility. The SLNs were characterized by particle size analysis via dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), drug encapsulation efficiency and in vitro drug release studies. Particle size of SLN dispersion prepared via the three preparation techniques was approximately 66 nm and that of redispersed lyophilizates was below 500 nm. TEM images showed spherical to oval particles that were less dense in the core with a well-defined shell and the particle size was in agreement with the particle size analysis data obtained by DLS. DSC thermograms of the lyophilized SLNs indicate a reduction in the crystallinity order of GMS particles. The drug encapsulation efficiency was found to be approximately 30%. In vitro drug release studies from redispersed lyophilized SLNs showed that 17 % of the encapsulated drug was released within 2 h. The SLNs prepared in our lab demonstrated characteristics that can potentially be utilized in an anticancer drug delivery system. Future in vitro cell culture and in vivo animal model studies will delineate compatibility and utility of these formulations in biological systems.

IF-WS{sub 2} nanoparticles size design and synthesis via chemical reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghoreishi, S.M., E-mail: ghoreshi@cc.iut.ac.ir; Meshkat, S.S.; Dadkhah, A.A.

2010-05-15

An innovative synthesis of inorganic fullerene-like disulfide tungsten (IF-WS{sub 2}) nanoparticles was developed using a chemical reduction reaction in a horizontal quartz reactor. In this process, first tungsten trisulfide (WS{sub 3}) was formed via a chemical reaction of tetra thiotungstate ammonium ((NH{sub 4}){sub 2}WS{sub 4}), polyethylene glycol (PEG), and hydrochloric acid (HCl) at ambient temperature and pressure. Subsequently, WS{sub 3} was reacted with hydrogen (H{sub 2}) at high temperature (1173-1373 K) in a quartz tube. The produced WS{sub 2} nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and transmission electron microscopy (TEM). Themore » characterization results indicated that the high-purity (100%) IF-WS{sub 2} nanoparticles were produced. Moreover, addition of surfactant (PEG) and higher operating temperature (1173-1373 K) decreased the particles agglomeration, and consequently led to the reduction of average diameter of WS{sub 2} particles in the range of 50-78 nm. The developed method is simple, environmentally compatible, and cost-effective in contrast to the conventional techniques.« less

Concentrated energy addition for active drag reduction in hypersonic flow regime

NASA Astrophysics Data System (ADS)

Ashwin Ganesh, M.; John, Bibin

2018-01-01

Numerical optimization of hypersonic drag reduction technique based on concentrated energy addition is presented in this study. A reduction in wave drag is realized through concentrated energy addition in the hypersonic flowfield upstream of the blunt body. For the exhaustive optimization presented in this study, an in-house high precision inviscid flow solver has been developed. Studies focused on the identification of "optimum energy addition location" have revealed the existence of multiple minimum drag points. The wave drag coefficient is observed to drop from 0.85 to 0.45 when 50 Watts of energy is added to an energy bubble of 1 mm radius located at 74.7 mm upstream of the stagnation point. A direct proportionality has been identified between energy bubble size and wave drag coefficient. Dependence of drag coefficient on the upstream added energy magnitude is also revealed. Of the observed multiple minimum drag points, the energy deposition point (EDP) that offers minimum wave drag just after a sharp drop in drag is proposed as the most optimum energy addition location.

Robust Derivation of Risk Reduction Strategies

NASA Technical Reports Server (NTRS)

Richardson, Julian; Port, Daniel; Feather, Martin

2007-01-01

Effective risk reduction strategies can be derived mechanically given sufficient characterization of the risks present in the system and the effectiveness of available risk reduction techniques. In this paper, we address an important question: can we reliably expect mechanically derived risk reduction strategies to be better than fixed or hand-selected risk reduction strategies, given that the quantitative assessment of risks and risk reduction techniques upon which mechanical derivation is based is difficult and likely to be inaccurate? We consider this question relative to two methods for deriving effective risk reduction strategies: the strategic method defined by Kazman, Port et al [Port et al, 2005], and the Defect Detection and Prevention (DDP) tool [Feather & Cornford, 2003]. We performed a number of sensitivity experiments to evaluate how inaccurate knowledge of risk and risk reduction techniques affect the performance of the strategies computed by the Strategic Method compared to a variety of alternative strategies. The experimental results indicate that strategies computed by the Strategic Method were significantly more effective than the alternative risk reduction strategies, even when knowledge of risk and risk reduction techniques was very inaccurate. The robustness of the Strategic Method suggests that its use should be considered in a wide range of projects.

Seasonal body size reductions with warming covary with major body size gradients in arthropod species.

PubMed

Horne, Curtis R; Hirst, Andrew G; Atkinson, David

2017-03-29

Major biological and biogeographical rules link body size variation with latitude or environmental temperature, and these rules are often studied in isolation. Within multivoltine species, seasonal temperature variation can cause substantial changes in adult body size, as subsequent generations experience different developmental conditions. Yet, unlike other size patterns, these common seasonal temperature-size gradients have never been collectively analysed. We undertake the largest analysis to date of seasonal temperature-size gradients in multivoltine arthropods, including 102 aquatic and terrestrial species from 71 global locations. Adult size declines in warmer seasons in 86% of the species examined. Aquatic species show approximately 2.5-fold greater reduction in size per °C of warming than terrestrial species, supporting the hypothesis that greater oxygen limitation in water than in air forces aquatic species to exhibit greater plasticity in body size with temperature. Total percentage change in size over the annual cycle appears relatively constant with annual temperature range but varies between environments, such that the overall size reduction in aquatic-developing species (approx. 31%) is almost threefold greater than in terrestrial species (approx. 11%). For the first time, we show that strong correlations exist between seasonal temperature-size gradients, laboratory responses and latitudinal-size clines, suggesting that these patterns share common drivers. © 2017 The Author(s).

Component and System Sensitivity Considerations for Design of a Lunar ISRU Oxygen Production Plant

NASA Technical Reports Server (NTRS)

Linne, Diane L.; Gokoglu, Suleyman; Hegde, Uday G.; Balasubramaniam, Ramaswamy; Santiago-Maldonado, Edgardo

2009-01-01

Component and system sensitivities of some design parameters of ISRU system components are analyzed. The differences between terrestrial and lunar excavation are discussed, and a qualitative comparison of large and small excavators is started. The effect of excavator size on the size of the ISRU plant's regolith hoppers is presented. Optimum operating conditions of both hydrogen and carbothermal reduction reactors are explored using recently developed analytical models. Design parameters such as batch size, conversion fraction, and maximum particle size are considered for a hydrogen reduction reactor while batch size, conversion fraction, number of melt zones, and methane flow rate are considered for a carbothermal reduction reactor. For both reactor types the effect of reactor operation on system energy and regolith delivery requirements is presented.

Computational procedures for evaluating the sensitivity derivatives of vibration frequencies and Eigenmodes of framed structures

NASA Technical Reports Server (NTRS)

Fetterman, Timothy L.; Noor, Ahmed K.

1987-01-01

Computational procedures are presented for evaluating the sensitivity derivatives of the vibration frequencies and eigenmodes of framed structures. Both a displacement and a mixed formulation are used. The two key elements of the computational procedure are: (a) Use of dynamic reduction techniques to substantially reduce the number of degrees of freedom; and (b) Application of iterative techniques to improve the accuracy of the derivatives of the eigenmodes. The two reduction techniques considered are the static condensation and a generalized dynamic reduction technique. Error norms are introduced to assess the accuracy of the eigenvalue and eigenvector derivatives obtained by the reduction techniques. The effectiveness of the methods presented is demonstrated by three numerical examples.

What We Have Learned about Class Size Reduction in California. Capstone Report.

ERIC Educational Resources Information Center

Bohrnstedt, George W., Ed.; Stecher, Brian M., Ed.

This final report on the California Class Size Reduction (CSR) initiative summarizes findings from three earlier reports dating back to 1997. Chapter 1 recaps the history of California's CSR initiative and includes a discussion of what state leaders' expectations were when CSR was passed. The chapter also describes research on class-size reduction…

The Cost of Class Size Reduction: Advice for Policymakers. RAND Graduate School Dissertation.

ERIC Educational Resources Information Center

Reichardt, Robert E.

This dissertation provides information to state-level policymakers that will help them avoid two implementation problems seen in the past in California's class-size-reduction (CSR) reform. The first problem was that flat, per student reimbursement did not adequately cover costs in districts with larger pre-CSR class-sizes or smaller schools. The…

High-intensity focused ultrasound in the treatment of breast fibroadenomata (HIFU-F trial).

PubMed

Peek, M C L; Ahmed, M; Scudder, J; Baker, R; Charalampoudis, P; Pinder, S E; Douek, M

2017-10-02

High-intensity focussed ultrasound (HIFU) is a non-invasive ablative technique utilising the application of high frequency ultrasound (US) pressure waves to cause tissue necrosis. This emerging technology is currently limited by prolonged treatment times. The aim of the HIFU-F trial was to perform circumferential HIFU treatment as a means of shortening treatment times. A prospective trial was set up to treat 50 consecutive patients ≥18 years of age. Eligible patients possessed symptomatic fibroadenomata, visible on US. Patients ≥25 years of age required histological confirmation of the diagnosis. Primary outcome measures were reduction in treatment time, reduction in volume on US after 12 months and complication rates. HIFU treatment was performed in 51 patients (53 treatments) with a mean age of 29.8 years (SD 7.2 years) and a diameter of 2.6 cm (SD 1.4 cm). Circumferential ablation reduced treatment times by an estimated 19.9 min (SD 25.1 min), which is a 29.4% (SD 15.2%) reduction compared with whole lesion ablation. Volume reduction of 43.2% (SD 35.4%; p < 0.005, paired t-test) was observed on US at 12 months post-treatment. Local complications completely resolved at 1 month apart from skin hyper-pigmentation, which persisted in nine cases at three months, six cases at 6 months and six at 12 months. Circumferential HIFU treatment for breast fibroadenomata is feasible to reduce both lesion size and treatment time. HIFU is a non-invasive alternative technique for the treatment of breast fibroadenomata. ISRCTN registration: 76622747.

Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis.

PubMed

Weston, Eleanor M; Lister, Adrian M

2009-05-07

Body size reduction in mammals is usually associated with only moderate brain size reduction, because the brain and sensory organs complete their growth before the rest of the body during ontogeny. On this basis, 'phyletic dwarfs' are predicted to have a greater relative brain size than 'phyletic giants'. However, this trend has been questioned in the special case of dwarfism of mammals on islands. Here we show that the endocranial capacities of extinct dwarf species of hippopotamus from Madagascar are up to 30% smaller than those of a mainland African ancestor scaled to equivalent body mass. These results show that brain size reduction is much greater than predicted from an intraspecific 'late ontogenetic' model of dwarfism in which brain size scales to body size with an exponent of 0.35. The nature of the proportional change or grade shift observed here indicates that selective pressures on brain size are potentially independent of those on body size. This study demonstrates empirically that it is mechanistically possible for dwarf mammals on islands to evolve significantly smaller brains than would be predicted from a model of dwarfing based on the intraspecific scaling of the mainland ancestor. Our findings challenge current understanding of brain-body allometric relationships in mammals and suggest that the process of dwarfism could in principle explain small brain size, a factor relevant to the interpretation of the small-brained hominin found on the Island of Flores, Indonesia.

Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis

PubMed Central

Weston, Eleanor M.; Lister, Adrian M.

2009-01-01

Body size reduction in mammals is usually associated with only moderate brain size reduction as the brain and sensory organs complete their growth before the rest of the body during ontogeny1,2. On this basis “phyletic dwarfs” are predicted to have a higher relative brain size than “phyletic giants”1,3. This trend has been questioned, however, in the special case of dwarfism of mammals on islands4. Here we show that the endocranial capacities of extinct dwarf species of hippopotamus from Madagascar are up to 30% smaller than those of a mainland African ancestor scaled to equivalent body mass. These results show brain size reduction is much greater than predicted from an intraspecific ‘late ontogenetic’ model of dwarfism where brain size scales to body size with an exponent of 0.35. The nature of the proportional change or grade shift2,5 observed here indicates that selective pressures upon brain size are potentially independent from those on body size. This study demonstrates empirically that it is mechanistically possible for dwarf mammals on islands to evolve significantly smaller brains than would be predicted from a model of dwarfing based on the intraspecific scaling of the mainland ancestor. Our findings challenge our understanding of brain-body allometric relationships in mammals and suggest that the process of dwarfism could in principle explain small brain size, a factor relevant to the interpretation of the small-brained hominin found on the Island of Flores, Indonesia6. PMID:19424156

Summary of an Analysis of Pupil-Teacher Ratio and Class Size: Differences That Make a Difference and Its Implications on Staffing for Class-Size Reduction.

ERIC Educational Resources Information Center

Sharp, Mark A.

The purpose of this paper was to share findings from an earlier study and to provide a framework for administrators to use in the implementation of class-size reduction (CSR) in their buildings. The study examined actual and average class size (CS), pupil-teacher ratios (PTR), and their differences. A primary goal was to clarify the ramifications…

The Efficacy, Safety and Applications of Medical Hypnosis.

PubMed

Häuser, Winfried; Hagl, Maria; Schmierer, Albrecht; Hansen, Ernil

2016-04-29

The efficacy and safety of hypnotic techniques in somatic medicine, known as medical hypnosis, have not been supported to date by adequate scientific evidence. We systematically reviewed meta-analyses of randomized controlled trials (RCTs) of medical hypnosis. Relevant publications (January 2005 to June 2015) were sought in the Cochrane databases CDSR and DARE, and in PubMed. Meta-analyses involving at least 400 patients were included in the present analysis. Their methodological quality was assessed with AMSTAR (A Measurement Tool to Assess Systematic Reviews). An additional search was carried out in the CENTRAL and PubMed databases for RCTs of waking suggestion (therapeutic suggestion without formal trance induction) in somatic medicine. Out of the 391 publications retrieved, five were reports of metaanalyses that met our inclusion criteria. One of these meta-analyses was of high methodological quality; three were of moderate quality, and one was of poor quality. Hypnosis was superior to controls with respect to the reduction of pain and emotional stress during medical interventions (34 RCTs, 2597 patients) as well as the reduction of irritable bowel symptoms (8 RCTs, 464 patients). Two meta-analyses revealed no differences between hypnosis and control treatment with respect to the side effects and safety of treatment. The effect size of hypnosis on emotional stress during medical interventions was low in one meta-analysis, moderate in one, and high in one. The effect size on pain during medical interventions was low. Five RCTs indicated that waking suggestion is effective in medical procedures. Medical hypnosis is a safe and effective complementary technique for use in medical procedures and in the treatment of irritable bowel syndrome. Waking suggestions can be a component of effective doctor-patient communication in routine clinical situations.

Investigation of the fiber/matrix interphase under high loading rates

NASA Astrophysics Data System (ADS)

Tanoglu, Metin

2000-10-01

This research focuses on characterization of the interphases of various sized E-glass-fiber/epoxy-amine systems under high loading rates. The systems include unsized, epoxy-amine compatible, and epoxy-amine incompatible glass fibers. A new experimental technique (dynamic micro-debonding technique) was developed to directly characterize the fiber/matrix interphase properties under various loading rates. Displacement rates of up to 3000 mum/sec that induce high-strain-rate interphase loading were obtained using the rapid expansion capability of the piezoelectric actuators (PZT). A straightforward data reduction scheme, which does not require complex numerical solutions, was also developed by employing thin specimens. This method enables quantification of the strength and specific absorbed energies due to debonding and frictional sliding. Moreover, the technique offers the potential to obtain the shear stress/strain response of the interphases at various rates. A new methodology was also developed to independently investigate the properties of the fiber/matrix interphase. This methodology is based on the assumption that the portion of sizing bound to the glass fiber strongly affects the interphase formation. Conventional burnout and acetone extraction experiments in conjunction with nuclear magnetic spectroscopy were used to determine the composition of the bound sizing. Using the determined composition, model interphase compounds were made to replicate the actual interphase and tested utilizing dynamic mechanical analyzer (DMA) and differential scanning calorimeter (DSC) techniques. The rate-dependent behavior of the model interphase materials and the bulk epoxy matrix were characterized by constructing storage modulus master curves as a function of strain rate using the time-temperature superposition principle. The results of dynamic micro-debonding experiments showed that the values of interphase strength and specific absorbed energies vary dependent on the sizing and exhibited significant sensitivity to loading rates. The unsized fibers exhibit greater energy-absorbing capability that could provide better ballistic resistance while the compatible sized fibers show higher strength values that improve the structural integrity of the polymeric composites. The calculated interphase shear modulus values from micro-debonding experiments increase with the loading rate consistent with DMA results. In addition, significantly higher amounts of energy are absorbed within the frictional sliding regime compared to debonding. Characterization of model interphase compounds revealed that the interphase formed due to the presence of bound sizing has a Tg below room temperature, a modulus more compliant than that of the bulk matrix, and a thickness of about 10 nm. The results showed that the properties of the interphases are significantly affected by the interphase network structure.

Graphene prepared by thermal reduction–exfoliation of graphite oxide: Effect of raw graphite particle size on the properties of graphite oxide and graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dao, Trung Dung; Jeong, Han Mo, E-mail: hmjeong@mail.ulsan.ac.kr

Highlights: • Effect of raw graphite particle size on properties of GO and graphene is reported. • Size of raw graphite affects oxidation degree and chemical structure of GO. • Highly oxidized GO results in small-sized but well-exfoliated graphene. • GO properties affect reduction degree, structure, and conductivity of graphene. - Abstract: We report the effect of raw graphite size on the properties of graphite oxide and graphene prepared by thermal reduction–exfoliation of graphite oxide. Transmission electron microscope analysis shows that the lateral size of graphene becomes smaller when smaller size graphite is used. X-ray diffraction analysis confirms that graphitemore » with smaller size is more effectively oxidized, resulting in a more effective subsequent exfoliation of the obtained graphite oxide toward graphene. X-ray photoelectron spectroscopy demonstrates that reduction of the graphite oxide derived from smaller size graphite into graphene is more efficient. However, Raman analysis suggests that the average size of the in-plane sp{sup 2}-carbon domains on graphene is smaller when smaller size graphite is used. The enhanced reduction degree and the reduced size of sp{sup 2}-carbon domains contribute contradictively to the electrical conductivity of graphene when the particle size of raw graphite reduces.« less

40 CFR 761.353 - Second level of sample selection.

Code of Federal Regulations, 2012 CFR

2012-07-01

... reduction is to limit the amount of time required to manually cut up larger particles of the waste to pass through a 9.5 millimeter (mm) screen. (a) Selecting a portion of the subsample for particle size reduction... table to select one of these quarters. (b) Reduction of the particle size by the use of a 9.5 mm screen...

40 CFR 761.353 - Second level of sample selection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... reduction is to limit the amount of time required to manually cut up larger particles of the waste to pass through a 9.5 millimeter (mm) screen. (a) Selecting a portion of the subsample for particle size reduction... table to select one of these quarters. (b) Reduction of the particle size by the use of a 9.5 mm screen...

40 CFR 761.353 - Second level of sample selection.

Code of Federal Regulations, 2013 CFR

2013-07-01

... reduction is to limit the amount of time required to manually cut up larger particles of the waste to pass through a 9.5 millimeter (mm) screen. (a) Selecting a portion of the subsample for particle size reduction... table to select one of these quarters. (b) Reduction of the particle size by the use of a 9.5 mm screen...

Combined electron energy-loss and cathodoluminescence spectroscopy on individual and composite plasmonic nanostructures

NASA Astrophysics Data System (ADS)

Coenen, Toon; Schoen, David T.; Brenny, Benjamin J. M.; Polman, Albert; Brongersma, Mark L.

2016-05-01

We systematically investigate the plasmonic "dolmen" geometry and its constituent elements using electron energy-loss spectroscopy and cathodoluminescence spectroscopy. In particular, we study the effects of the particle size and spacing on the resonant behavior and interparticle coupling. Because we apply both techniques on the same structures we can directly compare the results and investigate the radiative versus nonradiative character of the different modes. We find that the cathodoluminescence response is significantly lower than the electron energy-loss response for higher-energy modes because strong absorption reduces the scattering efficiency in this regime. Furthermore, we show that the overall resonant response roughly scales with size as expected for plasmonic structures but that the transverse resonant modes do become more dominant in larger structures due to a relative reduction in Ohmic dissipation. Using EELS and CL we can rigorously study coupling between the elements and show that the coupling diminishes for larger spacings.

Morphological and XPS study of ball milled Fe1-xAlx (0.3≤x≤0.6) alloys

NASA Astrophysics Data System (ADS)

Rajan, Sandeep; Kumar, Anil; Vyas, Anupam; Brajpuriya, Ranjeet

2018-05-01

The paper presents mechanical and XPS study of ball milled Fe1-xAlx (0.3≤x≤0.6) alloys. The author prepared the solid solution of Fe(Al) with different composition of Al by using mechanical alloying (MA) technique. The MA process induces a progressive dissolution of Al into Fe, resulted in the formation of an extended Fe(Al) solid solution with the bcc structure after 5 hr of milling. The SEM Images shows that the initial shape of particles disappeared completely, and their structure became a mixture of small and large angular-shaped crystallites with different sizes. The TEM micrograph also confirms the reduction in crystallite size and alloy formation. XPS study shows the shift in the binding energy position of both Fe and Al Peaks provide strong evidence of Fe(Al) phase formation after milling.

New insights in morphological analysis for managing activated sludge systems.

PubMed

Oliveira, Pedro; Alliet, Marion; Coufort-Saudejaud, Carole; Frances, Christine

2018-06-01

In activated sludge (AS) process, the impact of the operational parameters on process efficiency is assumed to be correlated with the sludge properties. This study provides a better insight into these interactions by subjecting a laboratory-scale AS system to a sequence of operating condition modifications enabling typical situations of a wastewater treatment plant to be represented. Process performance was assessed and AS floc morphology (size, circularity, convexity, solidity and aspect ratio) was quantified by measuring 100,000 flocs per sample with an automated image analysis technique. Introducing 3D distributions, which combine morphological properties, allowed the identification of a filamentous bulking characterized by a floc population shift towards larger sizes and lower solidity and circularity values. Moreover, a washout phenomenon was characterized by smaller AS flocs and an increase in their solidity. Recycle ratio increase and COD:N ratio decrease both promoted a slight reduction of floc sizes and a constant evolution of circularity and convexity values. The analysis of the volume-based 3D distributions turned out to be a smart tool to combine size and shape data, allowing a deeper understanding of the dynamics of floc structure under process disturbances.

Size effect on the structural, magnetic, and magnetotransport properties of electron doped manganite La0.15Ca0.85MnO3

NASA Astrophysics Data System (ADS)

Thomas, Rini; Das, Gangadhar; Mondal, Rajib; Pradheesh, R.; Mahato, R. N.; Geetha Kumary, T.; Nirmala, R.; Morozkin, A. V.; Lamsal, J.; Yelon, W. B.; Nigam, A. K.; Malik, S. K.

2012-04-01

Nanocrystalline La0.15Ca0.85MnO3 samples of various grain sizes ranging from ˜17 to 42 nm have been prepared by sol-gel technique. Phase purity and composition were verified by room temperature x-ray diffraction and SEM-EDAX analysis. The bulk La0.15Ca0.85MnO3 is known to order antiferromagnetically around 170 K and to undergo a simultaneous crystal structural transition. DC magnetization measurements on 17 nm size La0.15Ca0.85MnO3 show a peak at ˜130 K (TN) in zero-field-cooled (ZFC) state. Field-cooled magnetization bifurcates from ZFC data around 200 K hinting a weak ferromagnetic component near room temperature due to surface moments of the nanoparticle sample. Low temperature powder neutron diffraction experiments reveal that the incomplete structural transition from room temperature orthorhombic to low temperature orthorhombic-monoclinic state also occurs in the nanoparticle sample as in the bulk. Magnetization in the ordered state decreases as particle size increases, thus indicating the reduction of the competing ferromagnetic surface moments.

Comparison of the direct and indirect reduction techniques during the surgical management of posterior malleolar fractures.

PubMed

Shi, Hong-Fei; Xiong, Jin; Chen, Yi-Xin; Wang, Jun-Fei; Qiu, Xu-Sheng; Huang, Jie; Gui, Xue-Yang; Wen, Si-Yuan; Wang, Yin-He

2017-03-14

The optimal method for the reduction and fixation of posterior malleolar fracture (PMF) remains inconclusive. Currently, both of the indirect and direct reduction techniques are widely used. We aimed to compare the reduction quality and clinical outcome of posterior malleolar fracture managed with the direct reduction technique through posterolateral approach or the indirect reduction technique using ligamentotaxis. Patients with a PMF involving over 25% of the articular surface were recruited and assigned to the direct reduction (DR) group or the indirect reduction (IR) group. Following reduction and fixation of the fracture, the quality of fracture reduction was evaluated in post-operative CT images. Clinical and radiological follow-ups were performed at 6 weeks, 3 months, 6 months, 12 months, and then at 6 month-intervals postoperatively. Functional outcome (AOFAS score), ankle range of motion, and Visual Analog Scale (VAS) were evaluated at the last follow-up. Statistical differences were compared between the DR and IR groups considering the patient demographics, quality of fracture reduction, AOFAS score, and VAS. Totally 116 patients were included, wherein 64 cases were assigned to the DR group and 52 cases were assigned to the IR group. The quality of fracture reduction was significant higher in the DR group (P = 0.038). In the patients who completed a minimum of 12 months' follow-up, a median AOFAS score of 87 was recorded in the DR group, which was significantly higher than that recorded in the IR group (a median score of 80). The ankle range of motion was slightly better in the DR group, with the mean dorsiflexion restriction recorded to be 5.2° and 6.1° in the DR and IR group respectively (P = 0.331). Similar VAS score was observed in the two groups (P = 0.419). The direct reduction technique through a posterolateral approach provide better quality of fracture reduction and functional outcome in the management of PMF over 25% of articular surface, as compared with the indirect reduction technique using ligamentotaxis. NCT02801474 (retrospectively registered, June 2016, ClinicalTrails.gov).

Ultrasonically controlled particle size distribution of explosives: a safe method.

PubMed

Patil, Mohan Narayan; Gore, G M; Pandit, Aniruddha B

2008-03-01

Size reduction of the high energy materials (HEM's) by conventional methods (mechanical means) is not safe as they are very sensitive to friction and impact. Modified crystallization techniques can be used for the same purpose. The solute is dissolved in the solvent and crystallized via cooling or is precipitated out using an antisolvent. The various crystallization parameters such as temperature, antisolvent addition rate and agitation are adjusted to get the required final crystal size and morphology. The solvent-antisolvent ratio, time of crystallization and yield of the product are the key factors for controlling antisolvent based precipitation process. The advantages of cavitationally induced nucleation can be coupled with the conventional crystallization process. This study includes the effect of the ultrasonically generated acoustic cavitation phenomenon on the solvent antisolvent based precipitation process. CL20, a high-energy explosive compound, is a polyazapolycyclic caged polynitramine. CL-20 has greater energy output than existing (in-use) energetic ingredients while having an acceptable level of insensitivity to shock and other external stimuli. The size control and size distribution manipulation of the high energy material (CL20) has been successfully carried out safely and quickly along with an increase in the final mass yield, compared to the conventional antisolvent based precipitation process.

A comparative study of U937 cell size changes during apoptosis initiation by flow cytometry, light scattering, water assay and electronic sizing.

PubMed

Yurinskaya, Valentina; Aksenov, Nikolay; Moshkov, Alexey; Model, Michael; Goryachaya, Tatyana; Vereninov, Alexey

2017-10-01

A decrease in flow cytometric forward light scatter (FSC) is commonly interpreted as a sign of apoptotic cell volume decrease (AVD). However, the intensity of light scattering depends not only on the cell size but also on its other characteristics, such as hydration, which may affect the scattering in the opposite way. That makes estimation of AVD by FSC problematic. Here, we aimed to clarify the relationship between light scattering, cell hydration (assayed by buoyant density) and cell size by the Coulter technique. We used human lymphoid cells U937 exposed to staurosporine, etoposide or hypertonic stress as an apoptotic model. An initial increase in FSC was found to occur in apoptotic cells treated with staurosporine and hypertonic solutions; it is accompanied by cell dehydration and is absent in apoptosis caused by etoposide that is consistent with the lack of dehydration in this case. Thus, the effect of dehydration on the scattering signal outweighs the effect of reduction in cell size. The subsequent FSC decrease, which occurred in parallel to accumulation of annexin-positive cells, was similar in apoptosis caused by all three types of inducers. We conclude that an increase, but not a decrease in light scattering, indicates the initial cell volume decrease associated with apoptotic cell dehydration.

Comparison of selected analytical techniques for protein sizing, quantitation and molecular weight determination.

PubMed

Goetz, H; Kuschel, M; Wulff, T; Sauber, C; Miller, C; Fisher, S; Woodward, C

2004-09-30

Protein analysis techniques are developing fast due to the growing number of proteins obtained by recombinant DNA techniques. In the present paper we compare selected techniques, which are used for protein sizing, quantitation and molecular weight determination: sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), lab-on-a-chip or microfluidics technology (LoaC), size exclusion chromatography (SEC) and mass spectrometry (MS). We compare advantages and limitations of each technique in respect to different application areas, analysis time, protein sizing and quantitation performance.

Comparison of Solomon technique with selective laser ablation for twin-twin transfusion syndrome: a systematic review.

PubMed

Dhillon, R K; Hillman, S C; Pounds, R; Morris, R K; Kilby, M D

2015-11-01

To compare the Solomon and selective techniques for fetoscopic laser ablation (FLA) for the treatment of twin-twin transfusion syndrome (TTTS) in monochorionic-diamniotic twin pregnancies. This was a systematic review conducted in accordance with the PRISMA statement. Electronic searches were performed for relevant citations published from inception to September 2014. Selected studies included pregnancies undergoing FLA for TTTS that reported on recurrence of TTTS, occurrence of twin anemia-polycythemia sequence (TAPS) or survival. From 270 possible citations, three studies were included, two cohort studies and one randomized controlled trial (RCT), which directly compared the Solomon and selective techniques for FLA. The odds ratios (OR) of recurrent TTTS when using the Solomon vs the selective technique in the two cohort studies (n = 249) were 0.30 (95% CI, 0.00-4.46) and 0.45 (95% CI, 0.07-2.20). The RCT (n = 274) demonstrated a statistically significant reduction in risk of recurrent TTTS with the Solomon technique (OR, 0.21 (95% CI, 0.04-0.98); P = 0.03). The ORs for the development of TAPS following the Solomon and the selective techniques were 0.20 (95% CI, 0.00-2.46) and 0.61 (95% CI, 0.05-5.53) in the cohort studies and 0.16 (95% CI, 0.05-0.49) in the RCT, with statistically significant differences for the RCT only (P < 0.001). Observational evidence suggested overall better survival with the Solomon technique, which was statistically significant for survival of at least one twin. The RCT did not demonstrate a significant difference in survival between the two techniques, most probably owing to the small sample size and lack of power. This systematic review of observational, comparative cohort and RCT data suggests a trend towards a reduction in TAPS and recurrent TTTS and an increase in twin survival, with no increase in the occurrence of complications or adverse events, when using the Solomon compared to the selective technique for the treatment of TTTS. These findings need to be confirmed by an appropriately-powered RCT with long-term neurological follow-up. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

PAPR reduction in FBMC using an ACE-based linear programming optimization

NASA Astrophysics Data System (ADS)

van der Neut, Nuan; Maharaj, Bodhaswar TJ; de Lange, Frederick; González, Gustavo J.; Gregorio, Fernando; Cousseau, Juan

2014-12-01

This paper presents four novel techniques for peak-to-average power ratio (PAPR) reduction in filter bank multicarrier (FBMC) modulation systems. The approach extends on current PAPR reduction active constellation extension (ACE) methods, as used in orthogonal frequency division multiplexing (OFDM), to an FBMC implementation as the main contribution. The four techniques introduced can be split up into two: linear programming optimization ACE-based techniques and smart gradient-project (SGP) ACE techniques. The linear programming (LP)-based techniques compensate for the symbol overlaps by utilizing a frame-based approach and provide a theoretical upper bound on achievable performance for the overlapping ACE techniques. The overlapping ACE techniques on the other hand can handle symbol by symbol processing. Furthermore, as a result of FBMC properties, the proposed techniques do not require side information transmission. The PAPR performance of the techniques is shown to match, or in some cases improve, on current PAPR techniques for FBMC. Initial analysis of the computational complexity of the SGP techniques indicates that the complexity issues with PAPR reduction in FBMC implementations can be addressed. The out-of-band interference introduced by the techniques is investigated. As a result, it is shown that the interference can be compensated for, whilst still maintaining decent PAPR performance. Additional results are also provided by means of a study of the PAPR reduction of the proposed techniques at a fixed clipping probability. The bit error rate (BER) degradation is investigated to ensure that the trade-off in terms of BER degradation is not too severe. As illustrated by exhaustive simulations, the SGP ACE-based technique proposed are ideal candidates for practical implementation in systems employing the low-complexity polyphase implementation of FBMC modulators. The methods are shown to offer significant PAPR reduction and increase the feasibility of FBMC as a replacement modulation system for OFDM.

Highly active lanthanum doped ZnO nanorods for photodegradation of metasystox.

PubMed

Korake, P V; Dhabbe, R S; Kadam, A N; Gaikwad, Y B; Garadkar, K M

2014-01-05

La-doped ZnO nanorods with different La contents were synthesized by microwave assisted method and characterized by various sophisticated techniques such as XRD, UV-Vis., EDS, XPS, SEM and TEM. The XRD patterns of the La-doped ZnO indicate hexagonal crystal structure with an average crystallite size of 30nm. It was found that the crystallite size of La-doped ZnO is much smaller as compared to pure ZnO and decreases with increasing La content. The photocatalytic activity of 0.5mol% La-doped ZnO in the degradation of metasystox was studied. It was observed that degradation efficiency of metasystox over La-doped ZnO increases up to 0.5mol% doping then decreases for higher doping levels. Among the catalyst studied, the 0.5mol% La-doped ZnO was the most active, showing high photocatalytic activity for the degradation of metasystox. The maximum reduction of concentration of metasystox was observed under static condition at pH 8. Reduction in the Chemical Oxygen Demand (COD) of metasystox was observed after 150min. The cytotoxicological studies of meristematic root tip cells of Allium cepa were studied. The results obtained indicate that photocatalytically degraded products of metasystox were less toxic as compared to metasystox. Copyright © 2013 Elsevier B.V. All rights reserved.

Yttria catalyzed microstructural modifications in oxide dispersion strengthened V-4Cr-4Ti alloys synthesized by field assisted sintering technique

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran; Verma, Shailendra Kumar; Dash, Biswaranjan; Agrawal, Priyanka; Subramanian, Karthikeyan

2017-08-01

The present work deals with synthesis, characterisation and elevated temperature mechanical property evaluation of V-4Cr-4Ti and oxide (yttria = 0.3, 0.6 and 0.9 at%) dispersion strengthened V-4Cr-4Ti alloy processed by mechanical alloying and field-assisted sintering, under optimal conditions. Microstructural parameters of both powder and sintered samples were deduced by X-ray diffraction (XRD) and further confirmed with high resolution transmission electron microscopy. Powder diffraction and electron microscopy study show that ball milling of starting elemental powders (V-4Cr-4Ti) with and without yttria addition has resulted in single phase α-V (V-4Cr-4Ti) alloy. Wherein, XRD and electron microscopy images of sintered samples have revealed phase separation (viz., Cr-V and Ti-V) and domain size reduction, with yttria addition. The reasons behind phase separation and domain size reduction with yttria addition during sintering are extensively discussed. Microhardness and high temperature compression tests were done on sintered samples. Yttria addition (0.3 and 0.6 at.%) increases the elevated temperature compressive strength and strain hardening exponent of α-V alloys. High temperature compression test of 0.9 at% yttria dispersed α-V alloy reveals a glassy behaviour.

Flexible multibody simulation of automotive systems with non-modal model reduction techniques

NASA Astrophysics Data System (ADS)

Shiiba, Taichi; Fehr, Jörg; Eberhard, Peter

2012-12-01

The stiffness of the body structure of an automobile has a strong relationship with its noise, vibration, and harshness (NVH) characteristics. In this paper, the effect of the stiffness of the body structure upon ride quality is discussed with flexible multibody dynamics. In flexible multibody simulation, the local elastic deformation of the vehicle has been described traditionally with modal shape functions. Recently, linear model reduction techniques from system dynamics and mathematics came into the focus to find more sophisticated elastic shape functions. In this work, the NVH-relevant states of a racing kart are simulated, whereas the elastic shape functions are calculated with modern model reduction techniques like moment matching by projection on Krylov-subspaces, singular value decomposition-based reduction techniques, and combinations of those. The whole elastic multibody vehicle model consisting of tyres, steering, axle, etc. is considered, and an excitation with a vibration characteristics in a wide frequency range is evaluated in this paper. The accuracy and the calculation performance of those modern model reduction techniques is investigated including a comparison of the modal reduction approach.

The Impact of a Universal Class-Size Reduction Policy: Evidence from Florida's Statewide Mandate

ERIC Educational Resources Information Center

Chingos, Matthew M.

2012-01-01

Class-size reduction (CSR) mandates presuppose that resources provided to reduce class size will have a larger impact on student outcomes than resources that districts can spend as they see fit. I estimate the impact of Florida's statewide CSR policy by comparing the deviations from prior achievement trends in districts that were required to…

Reducing Class Size: A Smart Way To Improve America's Urban Schools. Second Edition.

ERIC Educational Resources Information Center

Naik, Manish; Casserly, Michael; Uro, Gabriela

The Council of the Great City Schools, a coalition of the largest urban public schools in the United States, surveyed its membership to determine how they were using federal class size reduction funds in the 2000-2001 school year. Thirty-six major urban school systems responded. Results indicate that the federal class size reduction program is…

Mineral Replacement Reactions as a Precursor to Strain Localisation: an (HR-)EBSD approach

NASA Astrophysics Data System (ADS)

Gardner, J.; Wheeler, J.; Wallis, D.; Hansen, L. N.; Mariani, E.

2017-12-01

Much remains to be learned about the links between metamorphism and deformation. Our work investigates the behaviour of fluid-mediated mineral replacement reaction products when exposed to subsequent shear stresses. We focus on albite from a metagabbro that has experienced metamorphism and subsequent deformation at greenschist facies, resulting in a reduction in grain size and associated strain localisation. EBSD maps show that prior to grain size reduction, product grains are highly distorted, yet they formed, and subsequently deformed, at temperatures at which extensive dislocation creep is unlikely. The Weighted Burgers Vector can be used to quantitatively describe the types of Burgers vectors present in geometrically necessary dislocation (GND) populations derived from 2-D EBSD map data. Application of this technique to the distorted product grains reveals the prominence of, among others, dislocations with apparent [010] Burgers vectors. This supports (with some caveats) the idea that dislocation creep is not responsible for the observed lattice distortion, as there are no known slip systems in plagioclase with a [010] Burgers vector. Distortion in a replacement microstructure has also been attributed to the presence of nanoscale product grains, which share very similar, but not identical, orientations due to topotactic nucleation from adjacent sites on the same substrate. As a precipitate, the product grains should be expected to be largely free of elastic strain. However, high angular resolution EBSD results demonstrate that product grains contain both elastic strains (> 10-3) and residual stresses (several hundred MPa), as well as GND densities on the order of 1014-1015 m-2. Thus we suggest the observed distortion (elastic strain plus rotations) in the lattice is produced during the mineral replacement reaction by a lattice mismatch and volume change between parent and product. Stored strain energy then provides a driving force for recovery and recrystallization. Recrystallization produces smaller grains with high angle boundaries, reducing the strength of, and allowing deformation to localise in, the albite phase. Grain size reduction in turn facilitates shear deformation to high strains by a grain size sensitive mechanism (fluid-assisted diffusion creep).

Exploring the CAESAR database using dimensionality reduction techniques

NASA Astrophysics Data System (ADS)

Mendoza-Schrock, Olga; Raymer, Michael L.

2012-06-01

The Civilian American and European Surface Anthropometry Resource (CAESAR) database containing over 40 anthropometric measurements on over 4000 humans has been extensively explored for pattern recognition and classification purposes using the raw, original data [1-4]. However, some of the anthropometric variables would be impossible to collect in an uncontrolled environment. Here, we explore the use of dimensionality reduction methods in concert with a variety of classification algorithms for gender classification using only those variables that are readily observable in an uncontrolled environment. Several dimensionality reduction techniques are employed to learn the underlining structure of the data. These techniques include linear projections such as the classical Principal Components Analysis (PCA) and non-linear (manifold learning) techniques, such as Diffusion Maps and the Isomap technique. This paper briefly describes all three techniques, and compares three different classifiers, Naïve Bayes, Adaboost, and Support Vector Machines (SVM), for gender classification in conjunction with each of these three dimensionality reduction approaches.

Monte Carlo simulations to assess the effects of tube current modulation on breast dose for multidetector CT

NASA Astrophysics Data System (ADS)

Angel, Erin; Yaghmai, Nazanin; Matilda Jude, Cecilia; DeMarco, John J.; Cagnon, Christopher H.; Goldin, Jonathan G.; Primak, Andrew N.; Stevens, Donna M.; Cody, Dianna D.; McCollough, Cynthia H.; McNitt-Gray, Michael F.

2009-02-01

Tube current modulation was designed to reduce radiation dose in CT imaging while maintaining overall image quality. This study aims to develop a method for evaluating the effects of tube current modulation (TCM) on organ dose in CT exams of actual patient anatomy. This method was validated by simulating a TCM and a fixed tube current chest CT exam on 30 voxelized patient models and estimating the radiation dose to each patient's glandular breast tissue. This new method for estimating organ dose was compared with other conventional estimates of dose reduction. Thirty detailed voxelized models of patient anatomy were created based on image data from female patients who had previously undergone clinically indicated CT scans including the chest area. As an indicator of patient size, the perimeter of the patient was measured on the image containing at least one nipple using a semi-automated technique. The breasts were contoured on each image set by a radiologist and glandular tissue was semi-automatically segmented from this region. Previously validated Monte Carlo models of two multidetector CT scanners were used, taking into account details about the source spectra, filtration, collimation and geometry of the scanner. TCM data were obtained from each patient's clinical scan and factored into the model to simulate the effects of TCM. For each patient model, two exams were simulated: a fixed tube current chest CT and a tube current modulated chest CT. X-ray photons were transported through the anatomy of the voxelized patient models, and radiation dose was tallied in the glandular breast tissue. The resulting doses from the tube current modulated simulations were compared to the results obtained from simulations performed using a fixed mA value. The average radiation dose to the glandular breast tissue from a fixed tube current scan across all patient models was 19 mGy. The average reduction in breast dose using the tube current modulated scan was 17%. Results were size dependent with smaller patients getting better dose reduction (up to 64% reduction) and larger patients getting a smaller reduction, and in some cases the dose actually increased when using tube current modulation (up to 41% increase). The results indicate that radiation dose to glandular breast tissue generally decreases with the use of tube current modulated CT acquisition, but that patient size (and in some cases patient positioning) may affect dose reduction.

CT breast dose reduction with the use of breast positioning and organ-based tube current modulation.

PubMed

Fu, Wanyi; Tian, Xiaoyu; Sturgeon, Gregory M; Agasthya, Greeshma; Segars, William Paul; Goodsitt, Mitchell M; Kazerooni, Ella A; Samei, Ehsan

2017-02-01

This study aimed to investigate the breast dose reduction potential of a breast-positioning (BP) technique for thoracic CT examinations with organ-based tube current modulation (OTCM). This study included 13 female anthropomorphic computational phantoms (XCAT, age range: 27-65 y.o., weight range: 52-105.8 kg). Each phantom was modified to simulate three breast sizes in standard supine geometry. The modeled breasts were then morphed to emulate BP that constrained the majority of the breast tissue inside the 120° anterior tube current (mA) reduction zone. The OTCM mA value was modeled using a ray-tracing program, which reduced the mA to 20% in the anterior region with a corresponding increase to the posterior region. The organ doses were estimated by a validated Monte Carlo program for a typical clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simulated organ doses and organ doses normalized by CTDI vol were used to compare three CT protocols: attenuation-based tube current modulation (ATCM), OTCM, and OTCM with BP (OTCM BP ). On average, compared to ATCM, OTCM reduced breast dose by 19.3 ± 4.5%, whereas OTCM BP reduced breast dose by 38.6 ± 8.1% (an additional 23.8 ± 9.4%). The dose saving of OTCM BP was more significant for larger breasts (on average 33, 38, and 44% reduction for 0.5, 1, and 2 kg breasts, respectively). Compared to ATCM, OTCM BP also reduced thymus and heart dose by 15.1 ± 7.4% and 15.9 ± 6.2% respectively. In thoracic CT examinations, OTCM with a breast-positioning technique can markedly reduce unnecessary exposure to radiosensitive organs in anterior chest wall, specifically breast tissue. The breast dose reduction is more notable for women with larger breasts. © 2016 American Association of Physicists in Medicine.

Superparamagnetic iron oxide nanoparticles with variable size and an iron oxidation state as prospective imaging agents.

PubMed

Kucheryavy, Pavel; He, Jibao; John, Vijay T; Maharjan, Pawan; Spinu, Leonard; Goloverda, Galina Z; Kolesnichenko, Vladimir L

2013-01-15

Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain γ-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r(1) and r(2) relaxivity measurements in water and diethylene glycol (for OH and CH(2) protons) have shown a decrease in the r(2)/r(1) ratio with the particle size reduction, which correlates with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe(3)O(4) with the same particle size, but their r(1) relaxivities are similar. Because the oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor and therefore may be a better prospective imaging agent because of its chemical stability.

Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

NASA Astrophysics Data System (ADS)

Anand, Madhu

Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Materials built from nanoparticles possess unique chemical, physical, mechanical and optical properties. Due to these properties, they hold potential in application areas such as catalysts, sensors, semiconductors and optics. At the same time, CO 2 in the form of supercritical fluid or CO2 gas-expanded liquid mixtures has gained significant attention in the area of processing nanostructures. This dissertation focuses on the synthesis and processing of nanoparticles using CO2 tunable solvent systems. Nanoparticle properties depend heavily on their size and, as such, the ability to finely control the size and uniformity of nanoparticles is of utmost importance. Solution based nanoparticle formation techniques are attractive due to their simplicity, but they often result in the synthesis of particles with a wide size range. To address this limitation, a post-synthesis technique has been developed in this dissertation to fractionate polydisperse nanoparticles ( s . = 30%) into monodisperse fractions ( s . = 8%) using tunable physicochemical properties of CO 2 expanded liquids, where CO2 is employed as an antisolvent. This work demonstrates that by controlling the addition of CO2 (pressurization) to an organic dispersion of nanoparticles, the ligand stabilized nanoparticles can be size selectively precipitated within a novel high pressure apparatus that confines the particle precipitation to a specified location on a surface. Unlike current techniques, this CO2 expanded liquid approach provides faster and more efficient particle size separation, reduction in organic solvent usage, and pressure tunable size selection in a single process. To improve our fundamental understanding and to further refine the size separation process, a detailed study has been performed to identify the key parameters enabling size separation of various nanoparticle populations. This study details the influence of various factors on the size separation process, such as the types of nanoparticles, ligand type and solvent type as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. This size selective precipitation technique was also applied to fractionate and separate polydisperse dispersions of CdSe/ZnS semiconductor nanocrystals into very distinct size and color fractions based solely on the pressure tunable solvent properties of CO2 expanded liquids. This size selective precipitation of nanoparticles is achieved by finely tuning the solvent strength of the CO2/organic solvent medium by simply adjusting the applied CO2 pressure. These subtle changes affect the balance between osmotic repulsive and van der Waals attractive forces thereby allowing fractionation of the nanocrystals into multiple narrow size populations. Thermodynamic analysis of nanoparticle size selective fractionation was performed to develop a theoretical model based on the thermodynamic properties of gas expanded liquids. We have used the general phenomenon of nanoparticle precipitation with CO2 expanded liquids to create dodecanethiol stabilized gold nanoparticle thin films. This method utilizes CO2 as an anti-solvent for low defect, wide area gold nanoparticle film formation employing monodisperse gold nanoparticles. Dodecanethiol stabilized gold particles are precipitated from hexane by controllably expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid then provides for removal of the organic solvent while avoiding the dewetting effects common to evaporating solvents. Unfortunately, the use of carbon dioxide as a neat solvent in nanoparticles synthesis and processing is limited by the very poor solvent strength of dense phase CO2. As a result, most current techniques employed to synthesize and disperse nanoparticles in neat carbon dioxide require the use of environmentally persistent fluorinated compounds as metal precursors and/or stabilizing ligands. This dissertation presents the first report of the simultaneous synthesis and stabilization of metallic nanoparticles in carbon dioxide solvent without the use of any fluorinated compounds thereby further enabling the use of CO 2 as a green solvent medium in nanomaterials synthesis and processing.

Reduction of Portion Size and Eating Rate Is Associated with BMI-SDS Reduction in Overweight and Obese Children and Adolescents: Results on Eating and Nutrition Behaviour from the Observational KgAS Study.

PubMed

Torbahn, Gabriel; Gellhaus, Ines; Koch, Benjamin; von Kries, Rüdiger; Obermeier, Viola; Holl, Reinhard W; Fink, Katharina; van Egmond-Fröhlich, Andreas

2017-01-01

Treatment of paediatric obesity focuses on changes of nutrition and eating behaviour and physical activity. The evaluation of the patient education programme by KgAS was utilised to analyse the association of changes of portion size, eating rate and dietary habits with BMI-SDS reductions. Patients (n = 297) were examined at the beginning and at the end of treatment and after 1-year follow-up at different out-patient centres. Their parents completed questionnaires including estimation of children's portion size, eating rate and frequency of food intake. Associations of 1- and 2-year changes in BMI-SDS and behaviour were calculated for patients with complete data in BMI-SDS, portion size, eating rate, frequency of green, yellow and red food intake (n = 131) by multiple linear regression models. Significant changes were found in the desired direction for BMI-SDS, portion size, eating rate and the intake of unfavourable red food items both after 1 and 2 years as well as for the consumption of favourable green food items after 1 year. Significant positive associations with BMI-SDS reduction after 1 and 2 years were detected for portion size (Cohen's f2 0.13 and 0.09) and eating rate (Cohen's f2 0.20 and 0.10), respectively. Reduced portion sizes and eating rates are associated with BMI-SDS reduction after 1 and 2 years. These findings suggest to focus on appropriate portion sizes and reduced eating rates in patient education programmes. © 2017 The Author(s) Published by S. Karger GmbH, Freiburg.

Uniformly sized gold nanoparticles derived from PS-b-P2VP block copolymer templates for the controllable synthesis of Si nanowires.

PubMed

Lu, Jennifer Q; Yi, Sung Soo

2006-04-25

A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires have been generated. The process described herein is fully compatible with existing semiconductor processing techniques and can be readily integrated into device fabrication.

Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

NASA Astrophysics Data System (ADS)

Zhang, Xiaoliang; Wang, Xiu; Kong, Wen; Yi, Gewen; Jia, Junhong

2011-10-01

In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

Harnessing the damping properties of materials for high-speed atomic force microscopy.

PubMed

Adams, Jonathan D; Erickson, Blake W; Grossenbacher, Jonas; Brugger, Juergen; Nievergelt, Adrian; Fantner, Georg E

2016-02-01

The success of high-speed atomic force microscopy in imaging molecular motors, enzymes and microbes in liquid environments suggests that the technique could be of significant value in a variety of areas of nanotechnology. However, the majority of atomic force microscopy experiments are performed in air, and the tapping-mode detection speed of current high-speed cantilevers is an order of magnitude lower in air than in liquids. Traditional approaches to increasing the imaging rate of atomic force microscopy have involved reducing the size of the cantilever, but further reductions in size will require a fundamental change in the detection method of the microscope. Here, we show that high-speed imaging in air can instead be achieved by changing the cantilever material. We use cantilevers fabricated from polymers, which can mimic the high damping environment of liquids. With this approach, SU-8 polymer cantilevers are developed that have an imaging-in-air detection bandwidth that is 19 times faster than those of conventional cantilevers of similar size, resonance frequency and spring constant.

The use of laminar tube flow in the study of hydrodynamic and chemical influences on polymer flocculation of Escherichia coli.

PubMed

Whittington, P N; George, N

1992-08-05

The optimization of microbial flocculation for subsequent biomass separation must relate the floc properties to separation process criteria. The effects of flocculant type, dose, and hydrodynamic conditions on floc formation in laminar tube flow were determined for an Escherichia coli system. Combined with an on-line aggregation sensor, this technique allows the flocculation process to be rapidly optimized. This is important, because interbatch variation in fermentation broth has consequences for flocculation control and subsequent downstream processing. Changing tube diameter and length while maintaining a constant flow rate allowed independent study of the effects of shear and time on the flocculation rate and floc characteristics. Tube flow at higher shear rates increased the rate and completeness of flocculation, but reduced the maximum floc size attained. The mechanism for this size limitation does not appear to be fracture or erosion of existing flocs. Rearrangement of particles within the flocs appears to be most likely. The Camp number predicted the extent of flocculation obtained in terms of the reduction in primary particle number, but not in terms of floc size.

Pulsed high energy synthesis of fine metal powders

NASA Technical Reports Server (NTRS)

Witherspoon, F. Douglas (Inventor); Massey, Dennis W. (Inventor)

1999-01-01

Repetitively pulsed plasma jets generated by a capillary arc discharge at high stagnation pressure (>15,000 psi) and high temperature (>10,000 K) are utilized to produce 0.1-10 .mu.m sized metal powders and decrease cost of production. The plasma jets impact and atomize melt materials to form the fine powders. The melt can originate from a conventional melt stream or from a pulsed arc between two electrodes. Gas streams used in conventional gas atomization are replaced with much higher momentum flux plasma jets. Delivering strong incident shocks aids in primary disintegration of the molten material. A series of short duration, high pressure plasma pulses fragment the molten material. The pulses introduce sharp velocity gradients in the molten material which disintegrates into fine particles. The plasma pulses have peak pressures of approximately one kilobar. The high pressures improve the efficiency of disintegration. High gas flow velocities and pressures are achieved without reduction in gas density. Repetitively pulsed plasma jets will produce powders with lower mean size and narrower size distribution than conventional atomization techniques.

On the connection between multigrid and cyclic reduction

NASA Technical Reports Server (NTRS)

Merriam, M. L.

1984-01-01

A technique is shown whereby it is possible to relate a particular multigrid process to cyclic reduction using purely mathematical arguments. This technique suggest methods for solving Poisson's equation in 1-, 2-, or 3-dimensions with Dirichlet or Neumann boundary conditions. In one dimension the method is exact and, in fact, reduces to cyclic reduction. This provides a valuable reference point for understanding multigrid techniques. The particular multigrid process analyzed is referred to here as Approximate Cyclic Reduction (ACR) and is one of a class known as Multigrid Reduction methods in the literature. It involves one approximation with a known error term. It is possible to relate the error term in this approximation with certain eigenvector components of the error. These are sharply reduced in amplitude by classical relaxation techniques. The approximation can thus be made a very good one.

Simple glucose reduction route for one-step synthesis of copper nanofluids

NASA Astrophysics Data System (ADS)

Shenoy, U. Sandhya; Shetty, A. Nityananda

2014-01-01

One-step method has been employed in the synthesis of copper nanofluids. Copper nitrate is reduced by glucose in the presence of sodium lauryl sulfate. The synthesized particles are characterized by X-ray diffraction technique for the phase structure; electron diffraction X-ray analysis for chemical composition; transmission electron microscopy and field emission scanning electron microscopy for the morphology; Fourier-transform infrared spectroscopy and ultraviolet-visible spectroscopy for the analysis of ingredients of the solution. Thermal conductivity, sedimentation and rheological measurements have also been carried out. It is found that the reaction parameters have considerable effect on the size of the particle formed and rate of the reaction. The techniques confirm that the synthesized particles are copper. The reported method showed promising increase in the thermal conductivity of the base fluid and is found to be reliable, simple and cost-effective method for preparing heat transfer fluids with higher stability.

Computational Reduction of Specimen Noise to Enable Improved Thermography Characterization of Flaws in Graphite Polymer Composites

NASA Technical Reports Server (NTRS)

Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

2014-01-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

An experimental evaluation of monochromatic x-ray beam position monitors at diamond light source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bloomer, Chris, E-mail: chris.bloomer@diamond.ac.uk; Rehm, Guenther; Dolbnya, Igor P.

Maintaining the stability of the X-ray beam relative to the sample point is of paramount importance for beamlines and users wanting to perform cutting-edge experiments. The ability to detect, and subsequently compensate for, variations in X-ray beam position with effective diagnostics has multiple benefits: a reduction in commissioning and start-up time, less ‘down-time’, and an improvement in the quality of acquired data. At Diamond Light Source a methodical evaluation of a selection of monochromatic X-ray Beam Position Monitors (XBPMs), using a range of position detection techniques, and from a range of suppliers, was carried out. The results of these experimentsmore » are presented, showing the measured RMS noise on the position measurement of each device for a given flux, energy, beam size, and bandwidth. A discussion of the benefits and drawbacks of each of the various devices and techniques is also included.« less

Drug Solubility: Importance and Enhancement Techniques

PubMed Central

Savjani, Ketan T.; Gajjar, Anuradha K.; Savjani, Jignasa K.

2012-01-01

Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response. Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Solubility is a major challenge for formulation scientist. Any drug to be absorbed must be present in the form of solution at the site of absorption. Various techniques are used for the enhancement of the solubility of poorly soluble drugs which include physical and chemical modifications of drug and other methods like particle size reduction, crystal engineering, salt formation, solid dispersion, use of surfactant, complexation, and so forth. Selection of solubility improving method depends on drug property, site of absorption, and required dosage form characteristics. PMID:22830056

Membrane processing technology in the food industry: food processing, wastewater treatment, and effects on physical, microbiological, organoleptic, and nutritional properties of foods.

PubMed

Kotsanopoulos, Konstantinos V; Arvanitoyannis, Ioannis S

2015-01-01

Membrane processing technology (MPT) is increasingly used nowadays in a wide range of applications (demineralization, desalination, stabilization, separation, deacidification, reduction of microbial load, purification, etc.) in food industries. The most frequently applied techniques are electrodialysis (ED), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). Several membrane characteristics, such as pore size, flow properties, and the applied hydraulic pressure mainly determine membranes' potential uses. In this review paper the basic membrane techniques, their potential applications in a large number of fields and products towards the food industry, the main advantages and disadvantages of these methods, fouling phenomena as well as their effects on the organoleptic, qualitative, and nutritional value of foods are synoptically described. Some representative examples of traditional and modern membrane applications both in tabular and figural form are also provided.

Monte Carlo-based Reconstruction in Water Cherenkov Detectors using Chroma

NASA Astrophysics Data System (ADS)

Seibert, Stanley; Latorre, Anthony

2012-03-01

We demonstrate the feasibility of event reconstruction---including position, direction, energy and particle identification---in water Cherenkov detectors with a purely Monte Carlo-based method. Using a fast optical Monte Carlo package we have written, called Chroma, in combination with several variance reduction techniques, we can estimate the value of a likelihood function for an arbitrary event hypothesis. The likelihood can then be maximized over the parameter space of interest using a form of gradient descent designed for stochastic functions. Although slower than more traditional reconstruction algorithms, this completely Monte Carlo-based technique is universal and can be applied to a detector of any size or shape, which is a major advantage during the design phase of an experiment. As a specific example, we focus on reconstruction results from a simulation of the 200 kiloton water Cherenkov far detector option for LBNE.

Computational reduction of specimen noise to enable improved thermography characterization of flaws in graphite polymer composites

NASA Astrophysics Data System (ADS)

Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

2014-05-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

Deforestation and stream warming affect body size of Amazonian fishes.

PubMed

Ilha, Paulo; Schiesari, Luis; Yanagawa, Fernando I; Jankowski, KathiJo; Navas, Carlos A

2018-01-01

Declining body size has been suggested to be a universal response of organisms to rising temperatures, manifesting at all levels of organization and in a broad range of taxa. However, no study to date evaluated whether deforestation-driven warming could trigger a similar response. We studied changes in fish body size, from individuals to assemblages, in streams in Southeastern Amazonia. We first conducted sampling surveys to validate the assumption that deforestation promoted stream warming, and to test the hypothesis that warmer deforested streams had reduced fish body sizes relative to cooler forest streams. As predicted, deforested streams were up to 6 °C warmer and had fish 36% smaller than forest streams on average. This body size reduction could be largely explained by the responses of the four most common species, which were 43-55% smaller in deforested streams. We then conducted a laboratory experiment to test the hypothesis that stream warming as measured in the field was sufficient to cause a growth reduction in the dominant fish species in the region. Fish reared at forest stream temperatures gained mass, whereas those reared at deforested stream temperatures lost mass. Our results suggest that deforestation-driven stream warming is likely to be a relevant factor promoting observed body size reductions, although other changes in stream conditions, like reductions in organic matter inputs, can also be important. A broad scale reduction in fish body size due to warming may be occurring in streams throughout the Amazonian Arc of Deforestation, with potential implications for the conservation of Amazonian fish biodiversity and food supply for people around the Basin.

Deforestation and stream warming affect body size of Amazonian fishes

PubMed Central

Yanagawa, Fernando I.; Jankowski, KathiJo; Navas, Carlos A.

2018-01-01

Declining body size has been suggested to be a universal response of organisms to rising temperatures, manifesting at all levels of organization and in a broad range of taxa. However, no study to date evaluated whether deforestation-driven warming could trigger a similar response. We studied changes in fish body size, from individuals to assemblages, in streams in Southeastern Amazonia. We first conducted sampling surveys to validate the assumption that deforestation promoted stream warming, and to test the hypothesis that warmer deforested streams had reduced fish body sizes relative to cooler forest streams. As predicted, deforested streams were up to 6 °C warmer and had fish 36% smaller than forest streams on average. This body size reduction could be largely explained by the responses of the four most common species, which were 43–55% smaller in deforested streams. We then conducted a laboratory experiment to test the hypothesis that stream warming as measured in the field was sufficient to cause a growth reduction in the dominant fish species in the region. Fish reared at forest stream temperatures gained mass, whereas those reared at deforested stream temperatures lost mass. Our results suggest that deforestation-driven stream warming is likely to be a relevant factor promoting observed body size reductions, although other changes in stream conditions, like reductions in organic matter inputs, can also be important. A broad scale reduction in fish body size due to warming may be occurring in streams throughout the Amazonian Arc of Deforestation, with potential implications for the conservation of Amazonian fish biodiversity and food supply for people around the Basin. PMID:29718960

Reducing the standard serving size of alcoholic beverages prompts reductions in alcohol consumption.

PubMed

Kersbergen, Inge; Oldham, Melissa; Jones, Andrew; Field, Matt; Angus, Colin; Robinson, Eric

2018-05-14

To test whether reducing the standard serving size of alcoholic beverages would reduce voluntary alcohol consumption in a laboratory (study 1) and a real-world drinking environment (study 2). Additionally, we modelled the potential public health benefit of reducing the standard serving size of on-trade alcoholic beverages in the United Kingdom. Studies 1 and 2 were cluster-randomized experiments. In the additional study, we used the Sheffield Alcohol Policy Model to estimate the number of deaths and hospital admissions that would be averted per year in the United Kingdom if a policy that reduces alcohol serving sizes in the on-trade was introduced. A semi-naturalistic laboratory (study 1), a bar in Liverpool, UK (study 2). Students and university staff members (study 1: n = 114, mean age = 24.8 years, 74.6% female), residents from local community (study 2: n = 164, mean age = 34.9 years, 57.3% female). In study 1, participants were assigned randomly to receive standard or reduced serving sizes (by 25%) of alcohol during a laboratory drinking session. In study 2, customers at a bar were served alcohol in either standard or reduced serving sizes (by 28.6-33.3%). Outcome measures were units of alcohol consumed within 1 hour (study 1) and up to 3 hours (study 2). Serving size condition was the primary predictor. In study 1, a 25% reduction in alcohol serving size led to a 20.7-22.3% reduction in alcohol consumption. In study 2, a 28.6-33.3% reduction in alcohol serving size led to a 32.4-39.6% reduction in alcohol consumption. Modelling results indicated that decreasing the serving size of on-trade alcoholic beverages by 25% could reduce the number of alcohol-related hospital admissions and deaths per year in the United Kingdom by 4.4-10.5% and 5.6-13.2%, respectively. Reducing the serving size of alcoholic beverages in the United Kingdom appears to lead to a reduction in alcohol consumption within a single drinking occasion. © 2018 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.

Rugometric and microtopographic inspection of teeth enamel

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Pereira, Pedro B.

2013-06-01

The roughness of teeth' enamel is an important parameter in orthodontics. One example is the application in the process of decreasing tooth-size by reducing the interproximal enamel surfaces (stripping) of teeth. In order to achieve smooth surfaces clinicians have been testing various methods and progressively improved this therapeutic technique. The evaluation the surface roughness following teeth interproximal reduction is fundamental in the process. In general tooth' surface is not flat presenting a variety of complex geometries. In this communication we will report on the metrological procedure employed on the rugometric and microtopographic inspection by optical active triangulation of raw and processed (interproximal stripping) tooth surfaces.

Compact instrument for fluorescence image-guided surgery

NASA Astrophysics Data System (ADS)

Wang, Xinghua; Bhaumik, Srabani; Li, Qing; Staudinger, V. Paul; Yazdanfar, Siavash

2010-03-01

Fluorescence image-guided surgery (FIGS) is an emerging technique in oncology, neurology, and cardiology. To adapt intraoperative imaging for various surgical applications, increasingly flexible and compact FIGS instruments are necessary. We present a compact, portable FIGS system and demonstrate its use in cardiovascular mapping in a preclinical model of myocardial ischemia. Our system uses fiber optic delivery of laser diode excitation, custom optics with high collection efficiency, and compact consumer-grade cameras as a low-cost and compact alternative to open surgical FIGS systems. Dramatic size and weight reduction increases flexibility and access, and allows for handheld use or unobtrusive positioning over the surgical field.

Surgical management of coracoid fractures: technical tricks and clinical experience.

PubMed

Hill, Brian W; Jacobson, Aaron R; Anavian, Jack; Cole, Peter A

2014-05-01

The coracoid process plays a pivotal role in the foundation of the coracoacromial arch and in cases of displaced fractures; surgical management may be warranted to avoid functional compromise or impingement. A direct approach through Langer's lines allows for easy exposure and direct visualization for an anatomic reduction of simple fractures through the shaft or base of the coracoid. An anterior approach for fractures that extend into the superior glenoid fossa allows for direct exposure to obtain an anatomic articular reduction and indirect reduction of the coracoid fracture. In cases where a complex glenoid or scapula neck/body fracture is being addressed simultaneously either a posterior Judet approach can be used with an indirect reduction method or a separate anterior approach must be combined to address it if not in continuity with the superior scapular segment. Implant selection, primarily interfragmentary screws or a buttress plate, should be based on the size of the fragment, the degree of comminution, and the degree of articular involvement to ensure adequate stabilization. The purpose of this manuscript was to describe a stepwise approach to the surgical management of displaced coracoid fractures, describe surgical tips and techniques, and to present the clinical outcomes in 22 patients after surgical treatment with this approach.

Security of Continuous-Variable Quantum Key Distribution via a Gaussian de Finetti Reduction

NASA Astrophysics Data System (ADS)

Leverrier, Anthony

2017-05-01

Establishing the security of continuous-variable quantum key distribution against general attacks in a realistic finite-size regime is an outstanding open problem in the field of theoretical quantum cryptography if we restrict our attention to protocols that rely on the exchange of coherent states. Indeed, techniques based on the uncertainty principle are not known to work for such protocols, and the usual tools based on de Finetti reductions only provide security for unrealistically large block lengths. We address this problem here by considering a new type of Gaussian de Finetti reduction, that exploits the invariance of some continuous-variable protocols under the action of the unitary group U (n ) (instead of the symmetric group Sn as in usual de Finetti theorems), and by introducing generalized S U (2 ,2 ) coherent states. Crucially, combined with an energy test, this allows us to truncate the Hilbert space globally instead as at the single-mode level as in previous approaches that failed to provide security in realistic conditions. Our reduction shows that it is sufficient to prove the security of these protocols against Gaussian collective attacks in order to obtain security against general attacks, thereby confirming rigorously the widely held belief that Gaussian attacks are indeed optimal against such protocols.

Security of Continuous-Variable Quantum Key Distribution via a Gaussian de Finetti Reduction.

PubMed

Leverrier, Anthony

2017-05-19

Establishing the security of continuous-variable quantum key distribution against general attacks in a realistic finite-size regime is an outstanding open problem in the field of theoretical quantum cryptography if we restrict our attention to protocols that rely on the exchange of coherent states. Indeed, techniques based on the uncertainty principle are not known to work for such protocols, and the usual tools based on de Finetti reductions only provide security for unrealistically large block lengths. We address this problem here by considering a new type of Gaussian de Finetti reduction, that exploits the invariance of some continuous-variable protocols under the action of the unitary group U(n) (instead of the symmetric group S_{n} as in usual de Finetti theorems), and by introducing generalized SU(2,2) coherent states. Crucially, combined with an energy test, this allows us to truncate the Hilbert space globally instead as at the single-mode level as in previous approaches that failed to provide security in realistic conditions. Our reduction shows that it is sufficient to prove the security of these protocols against Gaussian collective attacks in order to obtain security against general attacks, thereby confirming rigorously the widely held belief that Gaussian attacks are indeed optimal against such protocols.

PCA based clustering for brain tumor segmentation of T1w MRI images.

PubMed

Kaya, Irem Ersöz; Pehlivanlı, Ayça Çakmak; Sekizkardeş, Emine Gezmez; Ibrikci, Turgay

2017-03-01

Medical images are huge collections of information that are difficult to store and process consuming extensive computing time. Therefore, the reduction techniques are commonly used as a data pre-processing step to make the image data less complex so that a high-dimensional data can be identified by an appropriate low-dimensional representation. PCA is one of the most popular multivariate methods for data reduction. This paper is focused on T1-weighted MRI images clustering for brain tumor segmentation with dimension reduction by different common Principle Component Analysis (PCA) algorithms. Our primary aim is to present a comparison between different variations of PCA algorithms on MRIs for two cluster methods. Five most common PCA algorithms; namely the conventional PCA, Probabilistic Principal Component Analysis (PPCA), Expectation Maximization Based Principal Component Analysis (EM-PCA), Generalize Hebbian Algorithm (GHA), and Adaptive Principal Component Extraction (APEX) were applied to reduce dimensionality in advance of two clustering algorithms, K-Means and Fuzzy C-Means. In the study, the T1-weighted MRI images of the human brain with brain tumor were used for clustering. In addition to the original size of 512 lines and 512 pixels per line, three more different sizes, 256 × 256, 128 × 128 and 64 × 64, were included in the study to examine their effect on the methods. The obtained results were compared in terms of both the reconstruction errors and the Euclidean distance errors among the clustered images containing the same number of principle components. According to the findings, the PPCA obtained the best results among all others. Furthermore, the EM-PCA and the PPCA assisted K-Means algorithm to accomplish the best clustering performance in the majority as well as achieving significant results with both clustering algorithms for all size of T1w MRI images. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Water, Tara A. van de, E-mail: t.a.van.de.water@rt.umcg.nl; Lomax, Antony J.; Bijl, Hendrik P.

2012-02-01

Purpose: To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Methods: Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements.more » In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Results: Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. Conclusions: rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality of life during and after radiotherapy treatment.« less

Class Size Reduction in California: Summary of the 1998-99 Evaluation Findings.

ERIC Educational Resources Information Center

Stecher, Brian M.; Bohrnstedt, George W.

This report discusses the results of the third year--1998-99--of California's Class Size Reduction (CSR) program. Assessments of the program show that CSR was almost fully implemented by 1998-99, with over 92 percent of students in K-3 in classes of 20 or fewer students. Those K-3 classes that had not been reduced in size were concentrated in…

The Effect of Kindergarten Classroom Size Reduction on Second Grade Student Achievement: Evidence from California

ERIC Educational Resources Information Center

Funkhouser, Edward

2009-01-01

Because classroom size reduction (CSR) and standards based testing were implemented at the same time in California during the mid-1990s, it is difficult to isolate the effects of classroom size on outcomes from the effects of curriculum changes. As a result, the main comparison in this paper is very specific--the effect of reduced sized…

Focus on California's Class-Size Reduction: Smaller Classes Aim To Launch Early Literacy.

ERIC Educational Resources Information Center

McRobbie, Joan

Smaller class sizes in California were viewed as a way to improve K-3 education, especially in the area of literacy. The urgency to act prompted state leaders to adopt class-size reduction (CSR) without knowing for sure that it would work and without establishing a formal procedure for evaluating the program. This report looks at past research on…

Class-Size Reduction Program Evaluation, 2001-02. A Report to the North Carolina Department of Public Instruction.

ERIC Educational Resources Information Center

Speas, Carol

In 2001-2002, 23 schools in the Wake County Public School System (WCPSS), North Carolina, were provided with 40 teacher positions through the Class Size Reduction Program (CSR). Achievement results for students in reduced class sizes were compared with those of similar students in other CSR schools who did not choose the same grade for the project…

Studies on the reduction kinetics of hematite iron ore pellets with noncoking coals for sponge iron plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, M.; Mohapatra, P.; Patel, S.K.

2009-07-01

In the present investigation, fired pellets were made by mixing hematite iron ore fines of -100, -16+18, and -8+10 mesh size in different ratios and studies on their reduction kinetics in Lakhanpur, Orient OC-2 and Belpahar coals were carried out at temperatures ranging from 850{sup o}C to 1000{sup o}C with a view toward promoting the massive utilization of fines in ironmaking. The rate of reduction in all the fired iron ore pellets increased markedly with an increase in temperature up to 1000{sup o}C, and it was more intense in the first 30min. The values of activation energy, calculated from integralmore » and differential approaches, for the reduction of fired pellets (prepared from iron ore fines of -100 mesh size) in coals were found to be in the range 131-148 and 130-181 kJ mol{sup -1} (for =0.2 to 0.8), indicating the process is controlled by a carbon gasification reaction. The addition of selected larger size particles in the matrix of -100 mesh size fines up to the extent studied decreased the activation energy and slightly increased the reduction rates of resultant fired pellets. In comparison to coal, the reduction of fired pellets in char was characterized by significantly lower reduction rates and higher activation energy.« less

Large but uneven reduction in fish size across species in relation to changing sea temperatures.

PubMed

van Rijn, Itai; Buba, Yehezkel; DeLong, John; Kiflawi, Moshe; Belmaker, Jonathan

2017-09-01

Ectotherms often attain smaller body sizes when they develop at higher temperatures. This phenomenon, known as the temperature-size rule, has important consequences for global fisheries, whereby ocean warming is predicted to result in smaller fish and reduced biomass. However, the generality of this phenomenon and the mechanisms that drive it in natural populations remain unresolved. In this study, we document the maximal size of 74 fish species along a steep temperature gradient in the Mediterranean Sea and find strong support for the temperature-size rule. Importantly, we additionally find that size reduction in active fish species is dramatically larger than for more sedentary species. As the temperature dependence of oxygen consumption depends on activity levels, these findings are consistent with the hypothesis that oxygen is a limiting factor shaping the temperature-size rule in fishes. These results suggest that ocean warming will result in a sharp, but uneven, reduction in fish size that will cause major shifts in size-dependent interactions. Moreover, warming will have major implications for fisheries as the main species targeted for harvesting will show the most substantial declines in biomass. © 2017 John Wiley & Sons Ltd.

Porosity in plasma enhanced chemical vapor deposited SiCOH dielectrics: A comparative study

NASA Astrophysics Data System (ADS)

Grill, A.; Patel, V.; Rodbell, K. P.; Huang, E.; Baklanov, M. R.; Mogilnikov, K. P.; Toney, M.; Kim, H.-C.

2003-09-01

The low dielectric constant (k) of plasma enhanced chemical vapor deposited SiCOH films has been attributed to porosity in the films. We have shown previously that the dielectric constant of such materials can be extended from the typical k values of 2.7-2.9 to ultralow-k values of k=2.0. The reduction in the dielectric constants has been achieved by enhancing the porosity in the films through the addition of an organic material to the SiCOH precursor and annealing the films to remove the thermally less-stable organic fractions. In order to confirm the relation between dielectric constant and film porosity the latter has been evaluated for SiCOH films with k values from 2.8 to 2.05 using positron annihilation spectroscopy, positron annihilation lifetime spectroscopy, small angle x-ray scattering, specular x-ray reflectivity, and ellipsometric porosimetry measurements. It has been found that the SiCOH films with k=2.8 had no detectable porosity, however the porosity increased with decreasing dielectric constant reaching values of 28%-39% for k values of 2.05. The degree of porosity and the pore size determined by the dissimilar techniques agreed within reasonable limits, especially when one takes into account the small pore size in these films and the different assumptions used by the different techniques. The pore size increases with decreasing k, however the diameter remains below 5 nm for k=2.05, most of the pores being smaller than 2.5 nm.

The simulation of magnetic resonance elastography through atherosclerosis.

PubMed

Thomas-Seale, L E J; Hollis, L; Klatt, D; Sack, I; Roberts, N; Pankaj, P; Hoskins, P R

2016-06-14

The clinical diagnosis of atherosclerosis via the measurement of stenosis size is widely acknowledged as an imperfect criterion. The vulnerability of an atherosclerotic plaque to rupture is associated with its mechanical properties. The potential to image these mechanical properties using magnetic resonance elastography (MRE) was investigated through synthetic datasets. An image of the steady state wave propagation, equivalent to the first harmonic, can be extracted directly from finite element analysis. Inversion of this displacement data yields a map of the shear modulus, known as an elastogram. The variation of plaque composition, stenosis size, Gaussian noise, filter thresholds and excitation frequency were explored. A decreasing mean shear modulus with an increasing lipid composition was identified through all stenosis sizes. However the inversion algorithm showed sensitivity to parameter variation leading to artefacts which disrupted both the elastograms and quantitative trends. As noise was increased up to a realistic level, the contrast was maintained between the fully fibrous and lipid plaques but lost between the interim compositions. Although incorporating a Butterworth filter improved the performance of the algorithm, restrictive filter thresholds resulted in a reduction of the sensitivity of the algorithm to composition and noise variation. Increasing the excitation frequency improved the techniques ability to image the magnitude of the shear modulus and identify a contrast between compositions. In conclusion, whilst the technique has the potential to image the shear modulus of atherosclerotic plaques, future research will require the integration of a heterogeneous inversion algorithm. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimizing Metalloporphyrin-Catalyzed Reduction Reactions for In Situ Remediation of DOE Contaminants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlautman, Mark A.

2013-07-14

Past activities have resulted in a legacy of contaminated soil and groundwater at Department of Energy facilities nationwide. Uranium and chromium are among the most frequently encountered and highest-priority metal and radionuclide contaminants at DOE installations. Abiotic chemical reduction of uranium and chromium at contaminated DOE sites can be beneficial because the reduced metal species are less soluble in water, less mobile in the environment, and less toxic to humans and ecosystems. Although direct biological reduction has been reported for U(VI) and Cr(VI) in laboratory studies and at some field sites, the reactions can sometimes be slow or even inhibitedmore » due to unfavorable environmental conditions. One promising approach for the in-situ remediation of DOE contaminants is to develop electron shuttle catalysts that can be delivered precisely to the specific subsurface locations where contaminants reside. Previous research has shown that reduction of oxidized organic and inorganic contaminants often can be catalyzed by electron shuttle systems. Metalloporphyrins and their derivatives are well known electron shuttles for many biogeochemical systems, and thus were selected to study their catalytic capabilities for the reduction of chromium and uranium in the presence of reducing agents. Zero valent iron (ZVI) was chosen as the primary electron donor in most experimental systems. Research proceeded in three phases and the key findings of each phase are reported here. Phase I examined Cr(VI) reduction and utilized micro- and nano-sized ZVI as the electron donors. Electron shuttle catalysts tested were cobalt- and iron-containing metalloporphyrins and Vitamin B12. To aid in the recycle and reuse of the nano-sized ZVI and soluble catalysts, sol-gels and calcium-alginate gel beads were tested as immobilization/support matrices. Although the nano-sized ZVI could be incorporated within the alginate gel beads, preliminary attempts to trap it in sol-gels were not successful. Conversely, the water-soluble catalysts could be trapped within sol-gel matrices but they tended to leach out of the alginate gel beads during use. In general, immobilization of the nano-sized ZVI in gel beads and of the catalysts in sol-gels tended to result in slower rates of Cr(VI) reduction, but these effects could be overcome to some extent by using higher reactant/catalyst concentrations. In addition, the lowering of their effectiveness would likely be offset by the benefits obtained when recycling and reusing the materials because they were immobilized. Addition of the catalytic electron shuttles will be most useful when the micro-sized or nano-sized ZVI becomes less reactive with reaction time. Continued work in Phase II in the area of nano-sized ZVI immobilization led to procedures that were successful in incorporating the iron particles in sol-gel matrices. The water-soluble reductants sodium dithionite and L-ascorbic acid were also tested, but their use appeared to lead to formation of complexes with the uranyl cation which limited their effectiveness. Also, although the sol-gel supported nano-sized ZVI showed some promise at reducing uranium, the fluoride used in the sol-gel synthesis protocol appeared to lead to formation of uranyl-fluoride complexes that were less reactive. Because hexavalent chromium is an anion which does not form complexes with fluoride, it was used to demonstrate the intrinsic reactivity of the sol-gel immobilized nano-sized ZVI. Consistent with our observations in Phase I, the sol-gel matrix once again slowed down the reduction reaction but the expected benefits of recycle/reuse should outweigh this adverse effect. The major emphasis in Phase III of this study was to simultaneously incorporate nano-sized ZVI and water-soluble catalysts in the same sol-gel matrix. The catalysts utilized were cobalt complexes of uroporphyrin and protoporphyrin and Cr(VI) reduction was used to test the efficacy of the combined "catalyst + reductant" sol-gel matrix. When enough catalyst was added to the sol-gels, enhancement of the Cr(VI) reduction reaction was observed. At the lowest levels of catalyst addition, however, the rates of Cr(VI) reduction were similar to those systems which only used sol-gel immobilized nano-sized ZVI without any catalyst present. These findings suggest future areas of research that should be pursued to further optimize abiotic reduction reactions of metals with combined "catalyst + reductant" matrices.« less

Increasing hemoglobin oxygen saturation levels in sickle trait donor whole blood prevents hemoglobin S polymerization and allows effective white blood cell reduction by filtration.

PubMed

Stroncek, David F; Byrne, Karen M; Noguchi, Constance T; Schechter, Alan N; Leitman, Susan F

2004-09-01

BACKGROUND Red blood cell (RBC) components from donors with sickle cell trait (Hb AS) often occlude white blood cell (WBC) reduction filters. Techniques were investigated to successfully filter Hb AS donor blood by increasing the Hb oxygen saturation with storage bags and conditions suitable for transfusion products. Oxygenation kinetics were measured over 3 days in whole-blood units stored in standard-sized 600-mL polyvinylchloride (PVC) bags and whole-blood units divided into three equal parts and stored in standard-sized blood bags made from PVC, tri-2-(ethylhexyl)trimellitate (CLX) plastic, or Teflon. The filterability of Hb AS blood stored for 3 days was tested with whole-blood filters. Oxygen saturation levels did not increase in full whole-blood units from donors without sickle cell trait during 3 days of storage in 600-mL PVC bags. In divided Hb AS whole-blood units stored for 3 days, oxygen saturation levels increased from baseline levels of 45 to 56, 66, and 94 percent after storage in 600-mL PVC, CLX, and Teflon bags, respectively (n = 5, p < 0.02), and all components filtered completely. When full Hb AS whole-blood units from eight donors were stored for 3 days in 1.5-L CLX bags, all units filtered completely, but one had a high residual WBC count. Storage of Hb AS whole blood in large-capacity oxygen-permeable bags increases oxygen tension and allows more effective WBC reduction by filtration.

Periareolar techniques for mammary reduction and elevation.

PubMed

de Benito, J; Sanza, I F

1993-01-01

Between June 1990 and June 1992 we carried out 56 breast operations: 18 reductions, 32 mastopexies, and 6 implant changes. The surgical techniques used in all cases basically consisted of three phases: the periareolar incision, the creation of the superior pedicle with two medial and lateral flaps, and the "anchoring," crossed by both flaps in order to hold up the mammary gland. The diameter of the "doughnut" of skin that we had to deepidermize varied between 5 and 15 cm, thus raising the nipple-areola complex by as much as 10 cm. The volume of tissue removed from the hypertrophic breast ranged from 70 to 520 g. In 24 of the 32 mastopexies, the use of a silicone implant was necessary in order to provide greater volume, texture, and better mammary contour. In these cases the size of the prostheses varied between 120 and 300 cc. All patients completed the postop followup in the normal way. Only three patients suffered a slight dehiscence of the periareolar suture, which was solved within a few days of the operation by means of a Friedreich. The periareolar cutaneous pleats and the hardness of the breast gradually disappeared, as predicted, within a period of 3-4 months; afterward the breast looked perfectly natural.

Effects of cobalt precursor on pyrolyzed carbon-supported cobalt-polypyrrole as electrocatalyst toward oxygen reduction reaction

PubMed Central

2013-01-01

A series of non-precious metal electrocatalysts, namely pyrolyzed carbon-supported cobalt-polypyrrole, Co-PPy-TsOH/C, are synthesized with various cobalt precursors, including cobalt acetate, cobalt nitrate, cobalt oxalate, and cobalt chloride. The catalytic performance towards oxygen reduction reaction (ORR) is comparatively investigated with electrochemical techniques of cyclic voltammogram, rotating disk electrode and rotating ring-disk electrode. The results are analyzed and discussed employing physiochemical techniques of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, elemental analysis, and extended X-ray absorption fine structure. It shows that the cobalt precursor plays an essential role on the synthesis process as well as microstructure and performance of the Co-PPy-TsOH/C catalysts towards ORR. Among the studied Co-PPy-TsOH/C catalysts, that prepared with cobalt acetate exhibits the best ORR performance. The crystallite/particle size of cobalt and its distribution as well as the graphitization degree of carbon in the catalyst greatly affects the catalytic performance of Co-PPy-TsOH/C towards ORR. Metallic cobalt is the main component in the active site in Co-PPy-TsOH/C for catalyzing ORR, but some other elements such as nitrogen are probably involved, too. PMID:24229351

Reducing computational costs in large scale 3D EIT by using a sparse Jacobian matrix with block-wise CGLS reconstruction.

PubMed

Yang, C L; Wei, H Y; Adler, A; Soleimani, M

2013-06-01

Electrical impedance tomography (EIT) is a fast and cost-effective technique to provide a tomographic conductivity image of a subject from boundary current-voltage data. This paper proposes a time and memory efficient method for solving a large scale 3D EIT inverse problem using a parallel conjugate gradient (CG) algorithm. The 3D EIT system with a large number of measurement data can produce a large size of Jacobian matrix; this could cause difficulties in computer storage and the inversion process. One of challenges in 3D EIT is to decrease the reconstruction time and memory usage, at the same time retaining the image quality. Firstly, a sparse matrix reduction technique is proposed using thresholding to set very small values of the Jacobian matrix to zero. By adjusting the Jacobian matrix into a sparse format, the element with zeros would be eliminated, which results in a saving of memory requirement. Secondly, a block-wise CG method for parallel reconstruction has been developed. The proposed method has been tested using simulated data as well as experimental test samples. Sparse Jacobian with a block-wise CG enables the large scale EIT problem to be solved efficiently. Image quality measures are presented to quantify the effect of sparse matrix reduction in reconstruction results.

High-density force myography: A possible alternative for upper-limb prosthetic control.

PubMed

Radmand, Ashkan; Scheme, Erik; Englehart, Kevin

2016-01-01

Several multiple degree-of-freedom upper-limb prostheses that have the promise of highly dexterous control have recently been developed. Inadequate controllability, however, has limited adoption of these devices. Introducing more robust control methods will likely result in higher acceptance rates. This work investigates the suitability of using high-density force myography (HD-FMG) for prosthetic control. HD-FMG uses a high-density array of pressure sensors to detect changes in the pressure patterns between the residual limb and socket caused by the contraction of the forearm muscles. In this work, HD-FMG outperforms the standard electromyography (EMG)-based system in detecting different wrist and hand gestures. With the arm in a fixed, static position, eight hand and wrist motions were classified with 0.33% error using the HD-FMG technique. Comparatively, classification errors in the range of 2.2%-11.3% have been reported in the literature for multichannel EMG-based approaches. As with EMG, position variation in HD-FMG can introduce classification error, but incorporating position variation into the training protocol reduces this effect. Channel reduction was also applied to the HD-FMG technique to decrease the dimensionality of the problem as well as the size of the sensorized area. We found that with informed, symmetric channel reduction, classification error could be decreased to 0.02%.

Fronto-orbital feminization technique. A surgical strategy using fronto-orbital burring with or without eggshell technique to optimize the risk/benefit ratio.

PubMed

Villepelet, A; Jafari, A; Baujat, B

2018-05-04

The demand for facial feminization is increasing in transsexual patients. Masculine foreheads present extensive supraorbital bossing with a more acute glabellar angle, whereas female foreheads show softer features. The aim of this article is to describe our surgical technique for fronto-orbital feminization. The mask-lift technique is an upper face-lift. It provides rejuvenation by correcting collapsed features, and fronto-orbital feminization through burring of orbital rims and lateral canthopexies. Depending on the size of the frontal sinus and the thickness of its anterior wall, frontal remodeling is achieved using simple burring or by means of the eggshell technique. Orbital remodeling comprises a superolateral orbital opening, a reduction of ridges and a trough at the lateral orbital rim to support the lateral canthopexy. Frontal, corrugator and procerus myectomies, plus minimal scalp excision, complete the surgery. Our technique results in significant, natural-looking feminization. No complications were observed in our series of patients. The eggshell technique is an alternative to bone flap on over-pneumatized sinus. Fronto-orbital feminization fits into a wider surgical strategy. It can be associated to rhinoplasty, genioplasty, mandibular angle remodeling, face lift and laryngoplasty. Achieving facial feminization in 2 or 3 stages improves psychological and physiological tolerance. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

A geometrical optics approach for modeling aperture averaging in free space optical communication applications

NASA Astrophysics Data System (ADS)

Yuksel, Heba; Davis, Christopher C.

2006-09-01

Intensity fluctuations at the receiver in free space optical (FSO) communication links lead to a received power variance that depends on the size of the receiver aperture. Increasing the size of the receiver aperture reduces the power variance. This effect of the receiver size on power variance is called aperture averaging. If there were no aperture size limitation at the receiver, then there would be no turbulence-induced scintillation. In practice, there is always a tradeoff between aperture size, transceiver weight, and potential transceiver agility for pointing, acquisition and tracking (PAT) of FSO communication links. We have developed a geometrical simulation model to predict the aperture averaging factor. This model is used to simulate the aperture averaging effect at given range by using a large number of rays, Gaussian as well as uniformly distributed, propagating through simulated turbulence into a circular receiver of varying aperture size. Turbulence is simulated by filling the propagation path with spherical bubbles of varying sizes and refractive index discontinuities statistically distributed according to various models. For each statistical representation of the atmosphere, the three-dimensional trajectory of each ray is analyzed using geometrical optics. These Monte Carlo techniques have proved capable of assessing the aperture averaging effect, in particular, the quantitative expected reduction in intensity fluctuations with increasing aperture diameter. In addition, beam wander results have demonstrated the range-cubed dependence of mean-squared beam wander. An effective turbulence parameter can also be determined by correlating beam wander behavior with the path length.

Evidence of phase nucleation during olivine diffusion creep: a new perspective for mantle strain localisation

NASA Astrophysics Data System (ADS)

Précigout, Jacques; Stünitz, Holger

2017-04-01

Mantle strain localisation is of great importance for lithosphere dynamics, but the cause for this phenomenon remains very elusive, particularly in conditions of the strong and ductile uppermost mantle. In these latter, grain size reduction leading to diffusion creep in olivine is believed to be one of the best candidates to account for strain localisation. However, the mechanisms of grain size reduction in this regime are still poorly understood. Here we show the results of Griggs-type experiments that document grain size reduction and material weakening during wet olivine diffusion creep at 900 °C and 1.2 GPa. While occurring for both, mono-phase and two-phase aggregates, grain size reduction is coeval with strain localisation and local phase mixing in olivine-pyroxene aggregates. Based on evidence of fluid inclusions and cracks filled with a fine-grained phase mixture, we conclude that grain size reduces as a result of fluid-assisted nucleation. Cavitation induced by grain boundary sliding (creep cavitation) can be inferred, and may play a critical role for olivine grain size reduction. Amongst their implications for rock rheology in general, our findings highlight a key process for strain localisation in the ductile uppermost mantle. This study has been published under the reference: "Précigout, J., and Stünitz, H. (2016) Evidence of phase nucleation during olivine diffusion creep: a new perspective for mantle strain localisation. Earth and Planetary Science Letters 455: 94-105, doi:101016/j.epsl.2016.09.029".

Comparing fuel reduction treatments for reducing wildfire size and intensity in a boreal forest landscape of northeastern China.

PubMed

Wu, Zhiwei; He, Hong S; Liu, Zhihua; Liang, Yu

2013-06-01

Fuel load is often used to prioritize stands for fuel reduction treatments. However, wildfire size and intensity are not only related to fuel loads but also to a wide range of other spatially related factors such as topography, weather and human activity. In prioritizing fuel reduction treatments, we propose using burn probability to account for the effects of spatially related factors that can affect wildfire size and intensity. Our burn probability incorporated fuel load, ignition probability, and spread probability (spatial controls to wildfire) at a particular location across a landscape. Our goal was to assess differences in reducing wildfire size and intensity using fuel-load and burn-probability based treatment prioritization approaches. Our study was conducted in a boreal forest in northeastern China. We derived a fuel load map from a stand map and a burn probability map based on historical fire records and potential wildfire spread pattern. The burn probability map was validated using historical records of burned patches. We then simulated 100 ignitions and six fuel reduction treatments to compare fire size and intensity under two approaches of fuel treatment prioritization. We calibrated and validated simulated wildfires against historical wildfire data. Our results showed that fuel reduction treatments based on burn probability were more effective at reducing simulated wildfire size, mean and maximum rate of spread, and mean fire intensity, but less effective at reducing maximum fire intensity across the burned landscape than treatments based on fuel load. Thus, contributions from both fuels and spatially related factors should be considered for each fuel reduction treatment. Published by Elsevier B.V.

A combination of selected mapping and clipping to increase energy efficiency of OFDM systems

PubMed Central

Lee, Byung Moo; Rim, You Seung

2017-01-01

We propose an energy efficient combination design for OFDM systems based on selected mapping (SLM) and clipping peak-to-average power ratio (PAPR) reduction techniques, and show the related energy efficiency (EE) performance analysis. The combination of two different PAPR reduction techniques can provide a significant benefit in increasing EE, because it can take advantages of both techniques. For the combination, we choose the clipping and SLM techniques, since the former technique is quite simple and effective, and the latter technique does not cause any signal distortion. We provide the structure and the systematic operating method, and show the various analyzes to derive the EE gain based on the combined technique. Our analysis show that the combined technique increases the EE by 69% compared to no PAPR reduction, and by 19.34% compared to only using SLM technique. PMID:29023591

Hydrogenation Reactions of CO and CO2: New Insights through In Situ X-ray Spectroscopy and Chemical Transient Kinetics Experiments on Cobalt Catalysts

NASA Astrophysics Data System (ADS)

Ralston, Walter Thomas

The catalytic hydrogenations of CO and CO2 to more useful chemicals is not only beneficial in producing more valuable products and reducing dependence on fossil fuels, but present a scientific challenge in how to control the selectivity of these reactions. Using colloidal chemistry techniques, a high level of control over the synthesis of nanomaterials can be achieved, and by exploiting this fact a simple model system can be realized to understand the reaction of CO and CO2 on a molecular level. Specifically, this dissertation focuses on understanding cobalt materials for the conversion of CO and CO2 into more useful, valuable chemicals. Colloidally prepared cobalt nanoparticles with a narrow size distribution were supported in mesoporous SiO2 and TiO2 to study the effect of the support on the Co catalyzed hydrogenation of CO and CO2. The 10nm Co/SiO2 and Co/TiO2 catalysts were tested for CO and CO2 hydrogenation at 5 bar with a ratio to hydrogen of 1:2 and 1:3, respectively. In addition, the effect of Co oxidation state was studied by using different reduction pretreatment temperatures (250°C and 450°C). The results showed that for both hydrogenation reactions, Co/TiO2 had a high activity at both reduction temperatures compared to Co/SiO2. However, unlike Co/SiO2 which showed higher activity after 450°C reduction, Co/TiO2 had a higher activity after reduction at 250°C. Through synchrotron x-ray spectroscopy, it was concluded that the TiO2 was wetting the Co particle at higher reduction temperatures and dewetting at lower reduction temperatures. In addition to the wetting, CoO was observed to be the surface species on Co/TiO2 catalyst after reduction at low temperatures, which catalyzed both CO and CO2 hydrogenation reactions with higher activity than the Co metal obtained after reduction at 450°C. Classical steady-state measurements are limited in so much as they are often unable to provide information on individual reaction steps in complex reaction pathways. To attempt to circumvent this, a chemical transient kinetics (CTK) reactor was designed and built. Verification of the reactor was performed by evaluating a catalyst from the literature and confirming the results. A CoMgO catalyst was used to accomplish this, and our original findings show that at short time scales steric hindrances at the surface may push the product distribution towards olefinic rather than branched compounds. Continuing work on the CTK, two distinct particle sizes of Co nanoparticles were synthesized and tested under atmospheric conditions (H2:CO = 2:1) on the transient reactor. 4.3 nm Co and 9.5 nm Co were supported on MCF-17 to study the previously observed size effect, where Co nanoparticles lose activity at smaller sizes. It was found that indeed, the 4.3 nm Co are less active because they contain less CO dissociation sites, which are necessary for populating the surface with carbon monomers and spurring subsequent chain growth. The specific CO dissociation site was identified as the Co (221) step, of which larger Co particles have more and smaller Co particles have less. To investigate the nature of the MnO / Co3O4 interface, an in situ study using synchrotron radiation was undertaken. A sample of 6nm MnO nanoparticles loaded on mesoporous Co3O4 was studied with ambient pressure x-ray photoelectron spectroscopy, soft x-ray absorption spectroscopy at the Mn and Co L edges, and scanning transmission x-ray microscopy. X-ray measurements show that under reducing conditions of CO + H2, the MnO nanoparticles wet the Co surface until it is completely covered by a layer of MnO. Through the combination of techniques, it is shown that the system is catalytic active at the low pressures studied, and that the nature of the interface between MnO and Co3O4 is highly dependent on the temperature and gaseous environment it is prepared in. (Abstract shortened by ProQuest.).

Facile one step synthesis of novel TiO2 nanocoral by sol-gel method using Aloe vera plant extract

NASA Astrophysics Data System (ADS)

Venkatesh, K. S.; Krishnamoorthi, S. R.; Palani, N. S.; Thirumal, V.; Jose, Sujin P.; Wang, Fu-Ming; Ilangovan, R.

2015-05-01

Titanium oxide (TiO2) nanoparticles (NPs) were synthesized by sol gel method using Aloe vera plant extract as a biological capping agent and a cauliflower-nanocoral morphology was observed in this technique. The assynthesized TiO2 nanopowder was calcined at a range of temperatures (300-600 °C) for 1 h. The influence of A. vera plant extract on the thermal, structural and morphological properties of TiO2 nanopowder was evaluated. Thermogravimetric analysis/differential thermal analysis was employed to study the thermal properties of the assynthesized TiO2 nanopowder. The crystallinity, phase transformation and the crystallite size of the calcined samples were studied by X-ray diffraction technique. XRD result confirmed the presence of TiO2 with anatase phase. FT Raman spectra showed the Raman active modes pertaining to the TiO2 anatase phase and Raman band shift was also observed with respect to particle size variation. The different functional group vibrations of as dried pure A. vera plant extract were compared with the mixture of TiO2 and A. vera plant extract by FT-IR analysis. The scanning electron microscopy images apparently showed the formation of spherical shaped NPs and also it demonstrated the effect of A. vera plant extract on the reduction of particles size. The surface area of the TiO2 NPs was measured through Brunauer-Emmett-Teller analysis. Transmission electron microscopy images ascertained that the spherical shaped TiO2 NPs were formed with cauliflower-nanocoral morphology decorated with nanopolyps with the size range between 15 and 30 nm.

MULTI-SCALE MODELING AND APPROXIMATION ASSISTED OPTIMIZATION OF BARE TUBE HEAT EXCHANGERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bacellar, Daniel; Ling, Jiazhen; Aute, Vikrant

2014-01-01

Air-to-refrigerant heat exchangers are very common in air-conditioning, heat pump and refrigeration applications. In these heat exchangers, there is a great benefit in terms of size, weight, refrigerant charge and heat transfer coefficient, by moving from conventional channel sizes (~ 9mm) to smaller channel sizes (< 5mm). This work investigates new designs for air-to-refrigerant heat exchangers with tube outer diameter ranging from 0.5 to 2.0mm. The goal of this research is to develop and optimize the design of these heat exchangers and compare their performance with existing state of the art designs. The air-side performance of various tube bundle configurationsmore » are analyzed using a Parallel Parameterized CFD (PPCFD) technique. PPCFD allows for fast-parametric CFD analyses of various geometries with topology change. Approximation techniques drastically reduce the number of CFD evaluations required during optimization. Maximum Entropy Design method is used for sampling and Kriging method is used for metamodeling. Metamodels are developed for the air-side heat transfer coefficients and pressure drop as a function of tube-bundle dimensions and air velocity. The metamodels are then integrated with an air-to-refrigerant heat exchanger design code. This integration allows a multi-scale analysis of air-side performance heat exchangers including air-to-refrigerant heat transfer and phase change. Overall optimization is carried out using a multi-objective genetic algorithm. The optimal designs found can exhibit 50 percent size reduction, 75 percent decrease in air side pressure drop and doubled air heat transfer coefficients compared to a high performance compact micro channel heat exchanger with same capacity and flow rates.« less

Photothermal therapy of melanoma tumor using multiwalled carbon nanotubes.

PubMed

Sobhani, Zahra; Behnam, Mohammad Ali; Emami, Farzin; Dehghanian, Amirreza; Jamhiri, Iman

2017-01-01

Photothermal therapy (PTT) is a therapeutic method in which photon energy is transformed into heat rapidly via different operations to extirpate cancer. Nanoparticles, such as carbon nanotubes (CNTs) have exceptional optical absorbance in visible and near infrared spectra. Therefore, they could be a good converter to induce hyperthermia in PTT technique. In our study, for improving the dispersibility of multiwalled CNTs in water, the CNTs were oxidized (O-CNTs) and then polyethylene glycol (PEG) was used for wrapping the surface of nanotubes. The formation of a thin layer of PEG around the nanotubes was confirmed through Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy techniques. Results of thermogravimetric analysis showed that the amount of PEG component in the O-CNT-PEG was approximately 80% (w/w). Cell cytotoxicity study showed that O-CNT was less cytotoxic than pristine multiwalled nanotubes, and O-CNT-PEG had the lowest toxicity against HeLa and HepG2 cell lines. The effect of O-CNT-PEG in reduction of melanoma tumor size after PTT was evaluated. Cancerous mice were exposed to a continuous-wave near infrared laser diode (λ=808 nm, P =2 W and I =8 W/cm 2 ) for 10 minutes once in the period of the treatment. The average size of tumor in mice receiving O-CNT-PEG decreased sharply in comparison with those that received laser therapy alone. Results of animal studies indicate that O-CNT-PEG is a powerful candidate for eradicating solid tumors in PTT technique.

Liposuction-assisted four pedicle-based breast reduction (LAFPBR): A new safer technique of breast reduction for elderly patients.

PubMed

La Padula, Simone; Hersant, Barbara; Noel, Warren; Meningaud, Jean Paul

2018-05-01

As older people increasingly care for their body image and remain active longer, the demand for reduction mammaplasty is increasing in this population. Only a few studies of reduction mammaplasty have specifically focussed on the outcomes in elderly women. We developed a new breast reduction technique: the Liposuction-Assisted Four Pedicle-Based Breast Reduction (LAFPBR) that is especially indicated for elderly patients. The aim of this paper was to describe the LAFPBR technique and to determine whether it could be considered a safer option for elderly patients compared to the superomedial pedicle (SMP) technique. A retrospective study included sixty-two women aged 60 years and over who underwent bilateral breast reduction mammaplasty. Thirty-one patients underwent LAFPBR and 31 patients were operated using the SMP technique. Complications and patient satisfaction in both groups were analysed. Patient satisfaction was measured using a validated questionnaire: the client satisfaction questionnaire 8 (CSQ-8). The LAFPBR technique required less operating time, and avoided significant blood loss. Six minor complications were observed in SMP patients. No LAFPBR women developed a procedure-related complication. Patient satisfaction was high with a mean score of 29.65 in LAFPBR patients and 28.68 in SMP patients. The LAFPBR is an easy procedure that appears safer than SMP and results in a high satisfaction rate in elderly women. Copyright © 2018 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

When and how to operate the posterior malleolus fragment in trimalleolar fractures: a systematic literature review.

PubMed

Verhage, Samuel Marinus; Hoogendoorn, Jochem Maarten; Krijnen, Pieta; Schipper, Inger Birgitta

2018-05-12

Whether or not and how to fixate the posterior malleolus fracture seems to depend on the fracture fragment size and its amount of dislocation, but clear guidelines for daily practice are lacking. In this review, we summarize the literature on preferred treatment of the posterior fragment in trimalleolar fractures. A systematic review of publications between January 1995 and April 30 2017 on this topic in the PubMed, Embase, and Cochrane databases was performed according to the PRISMA statement. Seventeen (2 prospective and 15 retrospective) of the 180 identified studies were included. Six studies report on indications for fixation of posterior malleolus fracture fragments. Eleven studies compare different fixation approaches and techniques for the posterior fragment. Meta-analysis was not possible due to varying fixation criteria and outcomes. There was no clear association between posterior fragment size and functional outcome or development of osteoarthritis. The non-anatomical reduction of the fragment was of more influence on outcome. Radiological and functional outcome was better after open reduction and internal fixation via the posterolateral approach than after percutaneous anterior-to-posterior screw fixation. The posterior fragment size is not a clear indication for its fixation. A step-off, however, seems an important indicator for developing posttraumatic osteoarthritis and worse functional outcome. Posterior fragments involving the intra-articular surface need to be reduced and fixated to prevent postoperative persisting step-off. Furthermore, fixation of the posterior malleolus via an open posterolateral approach seems superior to percutaneous anterior-to-posterior fixation. However, these results need to be confirmed in a prospective comparative trial. Therapeutic level II.

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-07-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-04-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Extreme grain size reduction in dolomite: microstructures and mechanisms.

NASA Astrophysics Data System (ADS)

Kennedy, L.; White, J. C.

2007-12-01

Pure dolomite sample were deformed at room temperature and under a variety of confining pressures (0 - 100MPa) to examine the processes of grain size reduction. The dolomite is composed of > 97 vol. % dolomite with accessory quartz, calcite, tremolite, and muscovite and has been metamorphosed to amphibolite facies and subsequently annealed. At the hand sample scale, the rock is isotropic, except for minor, randomly oriented tremolite porphyroblasts, and weakly aligned muscovite. At the thin section scale, coarser grains have lobate grain boundaries, exhibit minor to no undulose extinction and few deformation twins, although well- developed subgrains are present. Growth twins are common, as is the presence of well developed {1011} cleavage. Mean grain size 476 microns, and porosity is essentially zero (Austin and Kennedy, 2006). Samples contain diagonal to subvertical faults. Fractures are lined with an exceptionally fine-grained, powdered dolomite. Even experiments done at no confining pressure and stopped before sliding on the fracture surfaces occurred had significant powdered gouge developed along the surfaces. In this regard, fracturing of low porosity, pure dolomite, with metamorphic textures (e.g. lobate, interlocking grain boundaries) results in the development of fine-grained gouge. As expected the dolomite exhibited an increase in strength with increasing confining pressure, with a maximum differential stress of ~400MPa at 100 MPa confining pressure. At each chosen confining pressure, two experiments were performed and stopped at different stages along the load-displacement curve: just before yield stress and at peak stress. Microstructures at each stage were observed in order to determine the possible mechanisms for extreme grain size reduction. SEM work shows that in samples with little to no apparent displacement along microfractures, extreme grain size reduction still exists, suggesting that frictional sliding and subsequent cataclasis may not be the mechanism responsible for grain size reduction. Within individual dolomite clasts, apparent Mode I cracks are also lined with powedered gouge. Alternative mechanisms for grain size reduction are explored. Austin et al. 2005, Geological Society, London, Special Publications, 243, 51-66.3.

Balloon osteoplasty--a new technique for reduction and stabilisation of impression fractures in the tibial plateau: a cadaver study and first clinical application.

PubMed

Ahrens, Philipp; Sandmann, Gunther; Bauer, Jan; König, Benjamin; Martetschläger, Frank; Müller, Dirk; Siebenlist, Sebastian; Kirchhoff, Chlodwig; Neumaier, Markus; Biberthaler, Peter; Stöckle, Ulrich; Freude, Thomas

2012-09-01

Fractures of the tibial plateau are among the most severe injuries of the knee joint and lead to advanced gonarthrosis if the reduction does not restore perfect joint congruency. Many different reduction techniques focusing on open surgical procedures have been described in the past. In this context we would like to introduce a novel technique which was first tested in a cadaver setup and has undergone its successful first clinical application. Since kyphoplasty demonstrated effective ways of anatomical correction in spine fractures, we adapted the inflatable instruments and used the balloon technique to reduce depressed fragments of the tibial plateau. The technique enabled us to restore a congruent cartilage surface and bone reduction. In this technique we see a useful new method to reduce depressed fractures of the tibial plateau with the advantages of low collateral damage as it is known from minimally invasive procedures.

Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis.

PubMed

Pantoja, Joe Luis; Ge, Liang; Zhang, Zhihong; Morrel, William G; Guccione, Julius M; Grossi, Eugene A; Ratcliffe, Mark B

2014-10-01

The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function. Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated. PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function. PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Reusing remediated CCA-treated wood

Treesearch

Carol A. Clausen

2003-01-01

Options for recycling and reusing chromated-copper-arsenate- (CCA) treated material include dimensional lumber and round wood size reduction, composites, and remediation. Size reduction by remilling, shaving, or resawing CCA-treated wood reduces the volume of landfilled waste material and provides many options for reusing used treated wood. Manufacturing composite...

Class Size Reduction and Urban Students. ERIC Digest.

ERIC Educational Resources Information Center

Schwartz, Wendy

Researchers have long investigated whether smaller classes improve student achievement. Their conclusions suggest that class size reduction (CSR) can result in greater in-depth coverage of subject matter by teachers, enhanced learning and stronger engagement by students, more personalized teacher-student relationships, and safer schools with fewer…

Seasonal thermoregulatory responses in mammals.

PubMed

Lovegrove, Barry G

2005-05-01

This study examined the proportional seasonal winter adjustments of total and mass-specific basal power (watts and watts g-1, respectively), thermal conductance (watts g-1 degrees C-1), non-shivering thermogenesis capacity (ratio of NST/basal power), body temperature ( degrees C), and body mass (g) of mammals. The responses are best summarized for three different body size classes; small mammals (<100 g), intermediate-sized mammals (0.1-10 kg), and large mammals (>10 kg). The principal adjustments of the small mammals center on energy conservation, especially the Dehnel Effect, the winter reduction in body size of as much as 50%, accompanied by reductions in mass-specific basal power. On average, these reductions reduce the total basal power approximately in direct proportion to the mass reductions. Reductions in mass-specific basal power are matched by concomitant reductions in conductance to maintain the setpoint body temperature during winter. The overall thermoregulatory adjustments in small mammals serve to (a) lower overall winter power consumption, (b) maintain the setpoint body temperature, and (c) lower the lower critical limit of thermoneutrality and hence thermoregulatory costs. In intermediate-size mammals, the seasonal response is centered more on increasing thermogenic capacity by increasing basal power and NST capacity, accompanied by predictable and large reductions in conductance. The Dehnel effect is negligible. Very large mammals undergo the largest reductions in total and mass-specific basal power and conductance. However, there are too few data to resolve whether the reductions in total basal power can be attributed to the Dehnel effect, because the moderate decreases in body mass may also be caused by nutritional stress. Apart from the seasonal changes in basal power, these observations are consistent with the predictions of Heldmaier's seasonal acclimatization model.

Tailored interphase structure for improved strength and energy absorption of composites

NASA Astrophysics Data System (ADS)

Gao, Xiao

Fiber reinforced polymeric composites are lightweight, high-strength and high impact-resistant materials used widely for various applications. It has been shown that the mechanical performance of composites are dependent on the interphase, a three-dimensional region of nanometer size in the vicinity of the fiber-matrix boundary that possesses properties different from those of either the fiber reinforcement or the matrix resin and governs the load transfer from matrix to fiber. This research conducts a systematic study on glass fiber-epoxy interphase structure by tailoring adhesion between constituents and the creation of textures to control strength and energy absorption through mechanical interlocking between glass fiber and epoxy matrix. Our objective is to establish the foundation for microstructural design and optimization of the composite's structural and impact performance. Two ways of roughening the glass fiber surface have been studied to create the mechanical interlocking between fiber and resin; the first technique involves forming in-situ islands on the glass fiber surface by using silane blends of Glycidoxypropyltrimethoxy silane (GPS) and Tetraethoxy silane (TEOS); the second technique applies a silane coupling agents based sizing with the incorporation of silica nanoparticles (Ludox TMA, 22 nm) onto the fiber surface. The microdroplet test was selected to characterize the influence of adhesion and mechanical interlocking effects on interphase properties of different sizing sized glass fiber reinforced epoxy systems. A suitable data reduction scheme enables the strength and specified energy absorbed due to debonding, dynamic sliding, and quasi-static sliding to be quantified. In order to validate the effect of tailored interphase structure, which is induced by creating mechanical interlocking between fiber and resin, on macroscopic composite properties, composite panels were made from these four different sizing sized glass fibers and tested using the punch shear test. The composite panel made from the hybrid sizing sized glass fiber exhibited improved strength and energy absorption consistent with the trends in micromechanical measurements. Through all failure stages under macromechanical testing, hybrid sizing sized glass fiber/epoxyamine composite panel shows an increase in the strength and total energy absorption by 13% and 26%, respectively, compared to the compatible sizing sized baseline. Both micromechanical and macromechanical tests demonstrate the significant influence of tailoring the interphase structure on improving the impact performance of the composites. The hybrid sizing with the incorporation of nanoparticles, in particular, can greatly improve the impact resistance (i.e. energy absorption) of composites without sacrificing its structural performance (i.e. strength).

Convergent evolution of reduced energy demands in extremophile fish

PubMed Central

Arias-Rodriguez, Lenin; Tobler, Michael

2017-01-01

Convergent evolution in organismal function can arise from nonconvergent changes in traits that contribute to that function. Theory predicts that low resource availability and high maintenance costs in extreme environments select for reductions in organismal energy demands, which could be attained through modifications of body size or metabolic rate. We tested for convergence in energy demands and underlying traits by investigating livebearing fish (genus Poecilia) that have repeatedly colonized toxic, hydrogen sulphide-rich springs. We quantified variation in body size and routine metabolism across replicated sulphidic and non-sulphidic populations in nature, modelled total organismal energy demands, and conducted a common-garden experiment to test whether population differences had a genetic basis. Sulphidic populations generally exhibited smaller body sizes and lower routine metabolic rates compared to non-sulphidic populations, which together caused significant reductions in total organismal energy demands in extremophile populations. Although both mechanisms contributed to variation in organismal energy demands, variance partitioning indicated reductions of body size overall had a greater effect than reductions of routine metabolism. Finally, population differences in routine metabolism documented in natural populations were maintained in common-garden reared individuals, indicating evolved differences. In combination with other studies, these results suggest that reductions in energy demands may represent a common theme in adaptation to physiochemical stressors. Selection for reduced energy demand may particularly affect body size, which has implications for life history evolution in extreme environments. PMID:29077740

Initial experience with a new articulating energy device for laparoscopic liver resection.

PubMed

Berber, Eren; Akyuz, Muhammet; Aucejo, Federico; Aliyev, Shamil; Aksoy, Erol; Birsen, Onur; Taskin, Eren

2014-03-01

Although significant advances have been made in laparoscopic liver resection (LLR), most techniques still rely on multiple energy devices and staplers, which increase operative costs. The aim of this study was to report the initial results of a new multifunctional energy device for hepatic parenchymal transection. Fourteen patients who underwent LLR using this new device were compared to 20 patients who had LLR using current laparoscopic techniques (CL). Data were collected prospectively. The groups were similar demographics and tumor type and size. Although the type of resection was similar between the groups, the parenchymal transection time was less in the Caiman group (32 ± 5 vs. 63 ± 4 min, respectively, p = 0.0001). The operative time was similar (194 ± 21 vs. 233 ± 16 min, respectively, p = 0.158). There was reduction of the number of advanced instrumentation used in the Caiman group, including the staplers. Estimated blood loss, size of surgical margin, and hospital stay were similar. There was no mortality, and morbidity was 7 % in the Caiman and 20 % in the CL group. This initial study shows that the new device is safe and efficient for LLR. Its main advantage is shortening of hepatic parenchymal transection time. This has implications for increasing efficiency and cost saving in LLR.

Numerical investigation of internal high-speed viscous flows using a parabolic technique

NASA Technical Reports Server (NTRS)

Anderson, O. L.; Power, G. D.

1985-01-01

A feasibility study has been conducted to assess the applicability of an existing parabolic analysis (ADD-Axisymmetric Diffuser Duct), developed previously for subsonic viscous internal flows, to mixed supersonic/subsonic flows with heat addition simulating a SCRAMJET combustor. A study was conducted with the ADD code modified to include additional convection effects in the normal momentum equation when supersonic expansion and compression waves are present. A set of test problems with weak shock and expansion waves have been analyzed with this modified ADD method and stable and accurate solutions were demonstrated provided the streamwise step size was maintained at levels larger than the boundary layer displacement thickness. Calculations made with further reductions in step size encountered departure solutions consistent with strong interaction theory. Calculations were also performed for a flow field with a flame front in which a specific heat release was imposed to simulate a SCRAMJET combustor. In this case the flame front generated relatively thick shear layers which aggravated the departure solution problem. Qualitatively correct results were obtained for these cases using a marching technique with the convective terms in the normal momentum equation suppressed. It is concluded from the present study that for the class of problems where strong viscous/inviscid interactions are present a global iteration procedure is required.

Transarterial Coil-Augmented Onyx Embolization for Brain Arteriovenous Malformation

PubMed Central

Gao, Xu; Liang, Guobiao; Li, Zhiqing; Wang, Xiaogang; Yu, Chunyong; Cao, Peng; Chen, Jun; Li, Jingyuan

2014-01-01

Summary Onyx has been widely adopted for the treatment of arteriovenous malformations (AVMs). However, its control demands operators accumulate a considerable learning curve. We describe our initial experience using a novel injection method for the embolization of AVMs. We retrospectively reviewed the data of all 22 patients with brain AVMs (12 men, 10 women; age range, 12-68 years; mean age, 43.2 years) treated by the transarterial coil-augmented Onyx injection technique. The size of the AVMs ranged from 25 mm to 70 mm (average 35.6 mm). The technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcome were evaluated. In every case, endovascular treatment (EVT) was completed. A total of 31 sessions were performed, with a mean injection volume of 6.1 mL (range, 1.5-16.0 mL). An average of 96.7% (range 85%-100%) estimated size reduction was achieved, and 18 AVMs could be completely excluded by EVT alone. The results remained stable on follow-up angiograms. A procedural complication occurred in one patient, with permanent mild neurologic deficit. Our preliminary series demonstrated that the coil-augmented Onyx injection technique is a valuable adjunct achieving excellent nidal penetration and improving the safety of the procedure. PMID:24556304

Analysis of Proportional Integral and Optimized Proportional Integral Controllers for Resistance Spot Welding System (RSWS) - A Performance Perspective

NASA Astrophysics Data System (ADS)

Rama Subbanna, S.; Suryakalavathi, M., Dr.

2017-08-01

This paper is an attempt to accomplish a performance analysis of the different control techniques on spikes reduction method applied on the medium frequency transformer based DC spot welding system. Spike reduction is an important factor to be considered while spot welding systems are concerned. During normal RSWS operation welding transformer’s magnetic core can become saturated due to the unbalanced resistances of both transformer secondary windings and different characteristics of output rectifier diodes, which causes current spikes and over-current protection switch-off of the entire system. The current control technique is a piecewise linear control technique that is inspired from the DC-DC converter control algorithms to register a novel spike reduction method in the MFDC spot welding applications. Two controllers that were used for the spike reduction portion of the overall applications involve the traditional PI controller and Optimized PI controller. Care is taken such that the current control technique would maintain a reduced spikes in the primary current of the transformer while it reduces the Total Harmonic Distortion. The performance parameter that is involved in the spikes reduction technique is the THD, Percentage of current spike reduction for both techniques. Matlab/SimulinkTM based simulation is carried out for the MFDC RSWS with KW and results are tabulated for the PI and Optimized PI controllers and a tradeoff analysis is carried out.

[Balloon osteoplasty as reduction technique in the treatment of tibial head fractures].

PubMed

Freude, T; Kraus, T M; Sandmann, G H

2015-10-01

Tibial plateau fractures requiring surgery are severe injuries of the lower extremities. Depending on the fracture pattern, the age of the patient, the range of activity and the bone quality there is a broad variation in adequate treatment.  This article reports on an innovative treatment concept to address split depression fractures (Schatzker type II) and depression fractures (Schatzker type III) of the tibial head using the balloon osteoplasty technique for fracture reduction. Using the balloon technique achieves a precise and safe fracture reduction. This internal osteoplasty combines a minimal invasive percutaneous approach with a gently rise of the depressed area and the associated protection of the stratum regenerativum below the articular cartilage surface. This article lights up the surgical procedure using the balloon technique in tibia depression fractures. Using the balloon technique a precise and safe fracture reduction can be achieved. This internal osteoplasty combines a minimally invasive percutaneous approach with a gentle raising of the depressed area and the associated protection of the regenerative layer below the articular cartilage surface. Fracture reduction by use of a tamper results in high peak forces over small areas, whereas by using the balloon the forces are distributed over a larger area causing less secondary stress to the cartilage tissue. This less invasive approach might help to achieve a better long-term outcome with decreased secondary osteoarthritis due to the precise and chondroprotective reduction technique.

HEKATE-A novel grazing incidence neutron scattering concept for the European Spallation Source.

PubMed

Glavic, Artur; Stahn, Jochen

2018-03-01

Structure and magnetism at surfaces and buried interfaces on the nanoscale can only be accessed by few techniques, one of which is grazing incidence neutron scattering. While the technique has its strongest limitation in a low signal and large background, due to the low scattering probability and need for high resolution, it can be expected that the high intensity of the European Spallation Source in Lund, Sweden, will make many more such studies possible, warranting a dedicated beamline for this technique. We present an instrument concept, Highly Extended K range And Tunable Experiment (HEKATE), for surface scattering that combines the advantages of two Selene neutron guides with unique capabilities of spatially separated distinct wavelength frames. With this combination, it is not only possible to measure large specular reflectometry ranges, even on free liquid surfaces, but also to use two independent incident beams with tunable sizes and resolutions that can be optimized for the specifics of the investigated samples. Further the instrument guide geometry is tuned for reduction of high energy particle background and only uses low to moderate supermirror coatings for high reliability and affordable cost.

HEKATE—A novel grazing incidence neutron scattering concept for the European Spallation Source

NASA Astrophysics Data System (ADS)

Glavic, Artur; Stahn, Jochen

2018-03-01

Structure and magnetism at surfaces and buried interfaces on the nanoscale can only be accessed by few techniques, one of which is grazing incidence neutron scattering. While the technique has its strongest limitation in a low signal and large background, due to the low scattering probability and need for high resolution, it can be expected that the high intensity of the European Spallation Source in Lund, Sweden, will make many more such studies possible, warranting a dedicated beamline for this technique. We present an instrument concept, Highly Extended K range And Tunable Experiment (HEKATE), for surface scattering that combines the advantages of two Selene neutron guides with unique capabilities of spatially separated distinct wavelength frames. With this combination, it is not only possible to measure large specular reflectometry ranges, even on free liquid surfaces, but also to use two independent incident beams with tunable sizes and resolutions that can be optimized for the specifics of the investigated samples. Further the instrument guide geometry is tuned for reduction of high energy particle background and only uses low to moderate supermirror coatings for high reliability and affordable cost.

Processing of carbamazepine-PEG 4000 solid dispersions with supercritical carbon dioxide: preparation, characterisation, and in vitro dissolution.

PubMed

Moneghini, M; Kikic, I; Voinovich, D; Perissutti, B; Filipović-Grcić, J

2001-07-03

The purpose of this study was to apply the attractive technique of the supercritical fluid to the preparation of solvent-free solid dispersions. In particular, the gas antisolvent crystallisation technique (GAS), using supercritical carbon dioxide as processing medium, has been considered to prepare an enhanced release dosage form for of the poorly soluble carbamazepine, employing PEG 4000 as a hydrophilic carrier. The physical characterisation of the systems using laser granulometer, powder X-ray diffraction, thermal analyses, and scanning electron microscopy was carried out in order to understand the influence of this technological process on the physical status of the drug. The results of the physical characterisation attested a substantial correspondence of the solid state of the drug before and after treatment with GAS technique, whereas a pronounced change in size and morphology of the drug crystals was noticed. The dramatic reduction of the dimensions and the better crystal shape, together with the presence of the hydrophilic polymer determined a remarkable enhancement of the in vitro drug dissolution rate.

Inactivation of Alicyclobacillus acidoterrestris ATCC 49025 spores in apple juice by pulsed light. Influence of initial contamination and required reduction levels.

PubMed

Ferrario, Mariana I; Guerrero, Sandra N

The purpose of this study was to analyze the response of different initial contamination levels of Alicyclobacillus acidoterrestris ATCC 49025 spores in apple juice as affected by pulsed light treatment (PL, batch mode, xenon lamp, 3pulses/s, 0-71.6J/cm 2 ). Biphasic and Weibull frequency distribution models were used to characterize the relationship between inoculum size and treatment time with the reductions achieved after PL exposure. Additionally, a second order polynomial model was computed to relate required PL processing time to inoculum size and requested log reductions. PL treatment caused up to 3.0-3.5 log reductions, depending on the initial inoculum size. Inactivation curves corresponding to PL-treated samples were adequately characterized by both Weibull and biphasic models (R adj 2 94-96%), and revealed that lower initial inoculum sizes were associated with higher inactivation rates. According to the polynomial model, the predicted time for PL treatment increased exponentially with inoculum size. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Importance of clay size minerals for Fe(III) respiration in a petroleum-contaminated aquifer

USGS Publications Warehouse

Shelobolina, Evgenya S.; Anderson, Robert T.; Vodyanitskii, Yury N.; Sivtsov, Anatolii V.; Yuretich, Richard; Lovely, Derek R.

2004-01-01

The availability of Fe(III)-bearing minerals for dissimilatory Fe(III) reduction was evaluated in sediments from a petroleum-contaminated sandy aquifer near Bemidji, Minnesota (USA). First, the sediments from a contaminated area of the aquifer, in which Fe(III) reduction was the predominant terminal electron accepting process, were compared with sediments from a nearby, uncontaminated site. Data from 0.5 m HCl extraction of different size fractions of the sediments revealed that the clay size fraction contributed a significant portion of the ‘bio-available’ Fe(III) in the background sediment and was the most depleted in ‘bio-available’ Fe(III) in the iron-reducing sediment. Analytical transmission electron microscopy (TEM) revealed the disappearance of thermodynamically unstable Fe(III) and Mn(IV) hydroxides (ferrihydrite and Fe vernadite), as well as a decrease in the abundance of goethite and lepidocrocite in the clay size fraction from the contaminated sediment. TEM observations and X-ray diffraction examination did not provide strong evidence of Fe(III)-reduction-related changes within another potential source of ‘bio-available’ Fe(III) in the clay size fraction – ferruginous phyllosilicates. However, further testing in the laboratory with sediments from the methanogenic portion of the aquifer that were depleted in microbially reducible Fe(III) revealed the potential for microbial reduction of Fe(III) associated with phyllosilicates. Addition of a clay size fraction from the uncontaminated sediment, as well as Fe(III)-coated kaolin and ferruginous nontronite SWa-1, as sources of poorly crystalline Fe(III) hydroxides and structural iron of phyllosilicates respectively, lowered steady-state hydrogen concentrations consistent with a stimulation of Fe(III) reduction in laboratory incubations of methanogenic sediments. There was no change in hydrogen concentration when non-ferruginous clays or no minerals were added. This demonstrated that Fe(III)-bearing clay size minerals were essential for microbial Fe(III) reduction and suggested that both potential sources of ‘bio-available’ Fe(III) in the clay size fraction, poorly crystalline Fe(III) hydroxides and structural Fe(III) of phyllosilicates, were important sources of electron acceptor for indigenous iron-reducing microorganisms in this aquifer.

Effects of Fragmented Fe Intermetallic Compounds on Ductility in Al-Si-Mg Alloys.

PubMed

Kim, JaeHwang; Kim, DaeHwan

2018-03-01

Fe is intentionally added in order to form the Fe intermetallic compounds (Fe-IMCs) during casting. Field emission scanning electron microscope with energy dispersive spectrometer (EDS) was conducted to understand microstructural changes and chemical composition analyses. The needlelike Fe-IMCs based on two dimensional observation with hundreds of micro size are modified to fragmented particles with the minimum size of 300 nm through clod rolling with 80% thickness reduction. The ratio of Fe:Si on the fragmented Fe-IMCs after 80% reduction is close to 1:1, representing the β-Al5FeSi. The yield and tensile strengths are increased with increasing reduction rate. On the other hand, the elongation is decreased with the 40% reduction, but slightly increased with the 60% reduction. The elongation is dramatically increased over two times for the specimen of 80% reduction compared with that of the as-cast. Fracture behavior is strongly affected by the morphology and size of Fe-IMCs. The fracture mode is changed from brittle to ductile with the microstructure modification of Fe-IMCs.

Selection of examples in case-based computer-aided decision systems

PubMed Central

Mazurowski, Maciej A.; Zurada, Jacek M.; Tourassi, Georgia D.

2013-01-01

Case-based computer-aided decision (CB-CAD) systems rely on a database of previously stored, known examples when classifying new, incoming queries. Such systems can be particularly useful since they do not need retraining every time a new example is deposited in the case base. The adaptive nature of case-based systems is well suited to the current trend of continuously expanding digital databases in the medical domain. To maintain efficiency, however, such systems need sophisticated strategies to effectively manage the available evidence database. In this paper, we discuss the general problem of building an evidence database by selecting the most useful examples to store while satisfying existing storage requirements. We evaluate three intelligent techniques for this purpose: genetic algorithm-based selection, greedy selection and random mutation hill climbing. These techniques are compared to a random selection strategy used as the baseline. The study is performed with a previously presented CB-CAD system applied for false positive reduction in screening mammograms. The experimental evaluation shows that when the development goal is to maximize the system’s diagnostic performance, the intelligent techniques are able to reduce the size of the evidence database to 37% of the original database by eliminating superfluous and/or detrimental examples while at the same time significantly improving the CAD system’s performance. Furthermore, if the case-base size is a main concern, the total number of examples stored in the system can be reduced to only 2–4% of the original database without a decrease in the diagnostic performance. Comparison of the techniques shows that random mutation hill climbing provides the best balance between the diagnostic performance and computational efficiency when building the evidence database of the CB-CAD system. PMID:18854606

The Impact of a Universal Class-Size Reduction Policy: Evidence from Florida's Statewide Mandate. Program on Education Policy and Governance Working Papers Series. PEPG 10-03

ERIC Educational Resources Information Center

Chingos, Matthew M.

2010-01-01

Class-size reduction (CSR) mandates presuppose that resources provided to reduce class size will have a larger impact on student outcomes than resources that districts can spend as they see fit. I estimate the impact of Florida's statewide CSR policy by comparing the deviations from prior achievement trends in districts that were required to…

20. VIEW OF THE INTERIOR OF THE ADVANCED SIZE REDUCTION ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. VIEW OF THE INTERIOR OF THE ADVANCED SIZE REDUCTION FACILITY USED TO CUT PLUTONIUM CONTAMINATED GLOVE BOXES AND MISCELLANEOUS LARGE EQUIPMENT DOWN TO AN EASILY PACKAGED SIZE FOR DISPOSAL. ROUTINE OPERATIONS WERE PERFORMED REMOTELY, USING HOISTS, MANIPULATOR ARMS, AND GLOVE PORTS TO REDUCE BOTH INTENSITY AND TIME OF RADIATION EXPOSURE TO THE OPERATOR. (11/6/86) - Rocky Flats Plant, Plutonium Fabrication, Central section of Plant, Golden, Jefferson County, CO

Adiabatic reduction of a model of stochastic gene expression with jump Markov process.

PubMed

Yvinec, Romain; Zhuge, Changjing; Lei, Jinzhi; Mackey, Michael C

2014-04-01

This paper considers adiabatic reduction in a model of stochastic gene expression with bursting transcription considered as a jump Markov process. In this model, the process of gene expression with auto-regulation is described by fast/slow dynamics. The production of mRNA is assumed to follow a compound Poisson process occurring at a rate depending on protein levels (the phenomena called bursting in molecular biology) and the production of protein is a linear function of mRNA numbers. When the dynamics of mRNA is assumed to be a fast process (due to faster mRNA degradation than that of protein) we prove that, with appropriate scalings in the burst rate, jump size or translational rate, the bursting phenomena can be transmitted to the slow variable. We show that, depending on the scaling, the reduced equation is either a stochastic differential equation with a jump Poisson process or a deterministic ordinary differential equation. These results are significant because adiabatic reduction techniques seem to have not been rigorously justified for a stochastic differential system containing a jump Markov process. We expect that the results can be generalized to adiabatic methods in more general stochastic hybrid systems.

Comprehensive Truck Size and Weight (TS&W) Study. Phase 1-synthesis, working paper 7 : truck costs and truck size and weight regulations

DOT National Transportation Integrated Search

2012-07-01

This report presents the Cost Benefit Analysis Test Plan for the national evaluation of the Los Angeles County Congestion Reduction Demonstration (LAC CRD) under the United States Department of Transportation (U.S. DOT) Congestion Reduction Demonstra...

California's Class Size Reduction: Implications for Equity, Practice & Implementation.

ERIC Educational Resources Information Center

Wexler, Edward; Izu, JoAnn; Carlos, Lisa; Fuller, Bruce; Hayward, Gerald; Kirst, Mike

When California implemented its class-size reduction (CSR) program in 1996, a number of questions regarding financial burdens, teacher shortages, scarcity of facilities, and collective bargaining were raised. This first-year implementation study aims to provide some contextual information as background for answering questions, to clarify these…

Comprehensive Truck Size and Weight (TS&W) Study. Phase 1-synthesis, working paper 6 : traffic operations and truck size and weight regulations

DOT National Transportation Integrated Search

2012-04-01

This report presents the Exogenous Factors Test Plan for the national evaluation of the Los Angeles County Congestion Reduction Demonstration (LAC CRD) under the United States Department of Transportation (U.S. DOT) Congestion Reduction Demonstration...

A Lesson in Classroom Size Reduction.

ERIC Educational Resources Information Center

Hymon, Steve

1997-01-01

The goal of California's classroom size reduction (CSR) program is to have 20 or fewer students in kindergarten through grade 3 classrooms. Districts receive $650 for each student in a reduced classroom. Describes how districts implemented the plan and offers five lessons from struggles and successes with CSR. A table displays average elementary…

Financing Class Size Reduction

ERIC Educational Resources Information Center

Achilles, C. M.

2005-01-01

Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in…

Field trial of a synthetic tsetse-repellent technology developed for the control of bovine trypanosomosis in Kenya.

PubMed

Bett, B; Randolph, T F; Irungu, P; Nyamwaro, S O; Kitala, P; Gathuma, J; Grace, D; Vale, G; Hargrove, J; McDermott, J

2010-12-01

We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to evaluate the effectiveness of a synthetic tsetse-repellent technology developed for the control of trypanosomosis in cattle. The technology was a repellent (2-methoxy 4-methylphenol) emitted from dispensers attached to collars worn by cattle. Treatment was allocated at the herd level to ensure adequate protection of all the animals in a herd, with measurements of effectiveness conducted at the individual-animal level. The trial began in April 2005 and ran for 16 months including a baseline phase of 4 months. We recruited 12 herds in each area using a restricted random-sampling technique and distributed them equally into intervention (repellent) and control groups. Sample size was determined using a formal power calculation. Effectiveness or minimal worthwhile difference was defined as a 50% reduction in the incidence of trypanosome infection in the treated versus control group (effectiveness below which the technology was considered by experts as not viable compared to existing control techniques). All the animals in the recruited herds were screened monthly (buffy-coat technique) for trypanosome infections. The analysis followed the principle of intention-to-treat by which subjects are analysed according to their initial treatment assignment, regardless of the mechanical performance of the device. Crude and adjusted effects of the technology were 23% (p<0.001) and 18% (p=0.08) reduction in the infection incidence in the treatment compared to the control groups, respectively. The impact of the technology estimated in this study did not achieve the threshold of 50% reduction in the trypanosome infection incidence set a priori to indicate effectiveness (p<0.001). We therefore concluded that the prototype repellent technology package was not sufficiently effective in reducing trypanosome infection incidence under natural tsetse challenge to merit commercial development. Copyright © 2010 Elsevier B.V. All rights reserved.

Technique for systematic bone reduction for fixed implant-supported prosthesis in the edentulous maxilla.

PubMed

Bidra, Avinash S

2015-06-01

Bone reduction for maxillary fixed implant-supported prosthodontic treatment is often necessary to either gain prosthetic space or to conceal the prosthesis-tissue junction in patients with excessive gingival display (gummy smile). Inadequate bone reduction is often a cause of prosthetic failure due to material fractures, poor esthetics, or inability to perform oral hygiene procedures due to unfavorable ridge lap prosthetic contours. Various instruments and techniques are available for bone reduction. It would be helpful to have an accurate and efficient method for bone reduction at the time of surgery and subsequently create a smooth bony platform. This article presents a straightforward technique for systematic bone reduction by transferring the patient's maximum smile line, recorded clinically, to a clear radiographic smile guide for treatment planning using cone beam computed tomography (CBCT). The patient's smile line and the amount of required bone reduction are transferred clinically by marking bone with a sterile stationery graphite wood pencil at the time of surgery. This technique can help clinicians to accurately achieve the desired bone reduction during surgery, and provide confidence that the diagnostic and treatment planning goals have been achieved. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Extensive Diminution of Particle Size and Amorphization of a Crystalline Drug Attained by Eminent Technology of Solid Dispersion: A Comparative Study.

PubMed

Singh, Gurjeet; Sharma, Shailesh; Gupta, Ghanshyam Das

2017-07-01

The present study emphasized on the use of solid dispersion technology to triumph over the drawbacks associated with the highly effective antihypertensive drug telmisartan using different polymers (poloxamer 188 and locust bean gum) and methods (modified solvent evaporation and lyophilization). It is based on the comparison between selected polymers and methods for enhancing solubility through particle size reduction. The results showed different profiles for particle size, solubility, and dissolution of formulated amorphous systems depicting the great influence of polymer/method used. The resulting amorphous solid dispersions were characterized using x-ray diffraction (XRD), differential scanning calorimetry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle size analysis. The optimized solid dispersion (TEL 19) prepared with modified locust bean gum using lyophilization technique showed reduced particle size of 184.5 ± 3.7 nm and utmost solubility of 702 ± 5.47 μg/mL in water, which is quite high as compared to the pure drug (≤1 μg/mL). This study showed that the appropriate selection of carrier may lead to the development of solid dispersion formulation with desired solubility and dissolution profiles. The optimized dispersion was later formulated into fast-dissolving tablets, and further optimization was done to obtain the tablets with desired properties.

Experimental evaluation of the optical quality of DMD SLM for its application as Fourier holograms displaying device

NASA Astrophysics Data System (ADS)

Molodtsov, D. Y.; Cheremkhin, P. A.; Krasnov, V. V.; Rodin, V. G.

2016-04-01

In this paper, the optical quality of micromirror DMD spatial light modulator (SLM) is evaluated and its applicability as an output device for holographic filters in dispersive correlators is analyzed. The possibility of using of DMD SLM extracted from consumer DLP-projector was experimentally evaluated by displaying of Fourier holograms. Software for displaying of holograms was developed. Experiments on holograms reconstruction was conducted with a different number of holograms pixels (and different placement on SLM). Reduction of number of pixels of output hologram (i.e. size of minimum resolvable element) led to improvement of reconstructed image quality. The evaluation shows that not every DMD-chip has acceptable optical quality for its application as display device for Fourier holograms. It was determined that major factor of reconstructed image quality degradation is a curvature of surface of SLM or its safety glass. Ranging hologram size allowed to estimate approximate size of sufficiently flat area of SLM matrix. For tested SLM it was about 1.5 mm. Further hologram size increase led to significant reconstructed image quality degradation. Developed and applied a technique allows to quickly estimate maximum size of holograms that can be displayed with specific SLM without significant degradation of reconstructed image. Additionally it allows to identify areas on the SLM with increased curvature of the surface.

Strain Gauge Balance Calibration and Data Reduction at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Ferris, A. T. Judy

1999-01-01

This paper will cover the standard force balance calibration and data reduction techniques used at Langley Research Center. It will cover balance axes definition, balance type, calibration instrumentation, traceability of standards to NIST, calibration loading procedures, balance calibration mathematical model, calibration data reduction techniques, balance accuracy reporting, and calibration frequency.

Design of Ultrathin Pt-Based Multimetallic Nanostructures for Efficient Oxygen Reduction Electrocatalysis.

PubMed

Lai, Jianping; Guo, Shaojun

2017-12-01

Nanocatalysts with high platinum (Pt) utilization efficiency are attracting extensive attention for oxygen reduction reactions (ORR) conducted at the cathode of fuel cells. Ultrathin Pt-based multimetallic nanostructures show obvious advantages in accelerating the sluggish cathodic ORR due to their ultrahigh Pt utilization efficiency. A focus on recent important developments is provided in using wet chemistry techniques for making/tuning the multimetallic nanostructures with high Pt utilization efficiency for boosting ORR activity and durability. First, new synthetic methods for multimetallic core/shell nanoparticles with ultrathin shell sizes for achieving highly efficient ORR catalysts are reviewed. To obtain better ORR activity and stability, multimetallic nanowires or nanosheets with well-defined structure and surface are further highlighted. Furthermore, ultrathin Pt-based multimetallic nanoframes that feature 3D molecularly accessible surfaces for achieving more efficient ORR catalysis are discussed. Finally, the remaining challenges and outlooks for the future will be provided for this promising research field. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-brightness laser imaging with tunable speckle reduction enabled by electroactive micro-optic diffusers.

PubMed

Farrokhi, Hamid; Rohith, Thazhe Madam; Boonruangkan, Jeeranan; Han, Seunghwoi; Kim, Hyunwoong; Kim, Seung-Woo; Kim, Young-Jin

2017-11-10

High coherence of lasers is desirable in high-speed, high-resolution, and wide-field imaging. However, it also causes unavoidable background speckle noise thus degrades the image quality in traditional microscopy and more significantly in interferometric quantitative phase imaging (QPI). QPI utilizes optical interference for high-precision measurement of the optical properties where the speckle can severely distort the information. To overcome this, we demonstrated a light source system having a wide tunability in the spatial coherence over 43% by controlling the illumination angle, scatterer's size, and the rotational speed of an electroactive-polymer rotational micro-optic diffuser. Spatially random phase modulation was implemented for the lower speckle imaging with over a 50% speckle reduction without a significant degradation in the temporal coherence. Our coherence control technique will provide a unique solution for a low-speckle, full-field, and coherent imaging in optically scattering media in the fields of healthcare sciences, material sciences and high-precision engineering.

Green synthesis and characterization of silver nanoparticles by leaf extracts of Cycas circinalis, Ficus amplissima, Commelina benghalensis and Lippia nodiflora

NASA Astrophysics Data System (ADS)

Johnson, I.; Prabu, H. Joy

2015-01-01

Biosynthesis of nanoparticles is a kind of bottom-up approach where the main reaction occurring is reduction. Since silver nanoparticles (AgNPs) have been used for infection prevention in medical field, it is more relevant to reduce their size using ancient Indian herbal plants. This method is good in anti-microbial efficiency against bacteria, viruses and other microorganisms and hence clearly enhances the medicinal usage of AgNPs. This type of green biosynthesis of nanoparticles has received increasing attention due to the growing need to develop safe, cost-effective and environmental-friendly technologies for nano-materials synthesis. In the process of synthesizing AgNPs, we observed a rapid reduction of silver ions leading to the formation of stable crystalline AgNPs in the solution. Plant extracts from Cycas circinalis, Ficus amplissima, Commelina benghalensis and Lippia nodiflora were used for the synthesis of AgNPs from silver nitrate solution. AgNPs were characterized by different techniques.

Preparing for in situ processing on upcoming leading-edge supercomputers

DOE PAGES

Kress, James; Churchill, Randy Michael; Klasky, Scott; ...

2016-10-01

High performance computing applications are producing increasingly large amounts of data and placing enormous stress on current capabilities for traditional post-hoc visualization techniques. Because of the growing compute and I/O imbalance, data reductions, including in situ visualization, are required. These reduced data are used for analysis and visualization in a variety of different ways. Many of he visualization and analysis requirements are known a priori, but when they are not, scientists are dependent on the reduced data to accurately represent the simulation in post hoc analysis. The contributions of this paper is a description of the directions we are pursuingmore » to assist a large scale fusion simulation code succeed on the next generation of supercomputers. Finally, these directions include the role of in situ processing for performing data reductions, as well as the tradeoffs between data size and data integrity within the context of complex operations in a typical scientific workflow.« less

Analytical study of acoustic response of a semireverberant enclosure with application to active noise control

NASA Technical Reports Server (NTRS)

Parrott, T. L.; Schein, D. B.; Gridley, D.

1985-01-01

The acoustic response of a semireverberant enclosure with two interacting, velocity-prescribed source distributions was analyzed using standard modal analysis techniques with a view toward a better understanding of active noise control. Different source and enclosure dimensions, source separations, and single-wall admittances were studied over representative frequency bandwidths of 10 Hz with source relative phase as a parameter. Results indicate that power radiated into the enclosure agree qualitatively with the spatial average of the mean square pressure, even though the reverberant field is nondiffuse. Decreases in acoustic power can therefore be used to estimate global noise reduction in a nondiffuse semireverberant environment. As might be expected, parametric studies indicate that maximum power reductions of up to 25 dB can be achieved when secondary and primary sources are compact and closely spaced. Although less success is achieved with increasing frequency and source separation or size, significant suppression of up to 8 dB still occurs over the 1 to 2 Hz bandwidth.

Ordered PdCu-Based Nanoparticles as Bifunctional Oxygen-Reduction and Ethanol-Oxidation Electrocatalysts

DOE PAGES

Jiang, Kezhu; Wang, Pengtang; Guo, Shaojun; ...

2016-06-02

Here, the development of superior non-platinum electrocatalysts for enhancing the electrocatalytic activity and stability for the oxygen-reduction reaction (ORR) and liquid fuel oxidation reaction is very important for the commercialization of fuel cells,but still agreat challenge.Herein, we demonstrate a new colloidal chemistry technique for making structurally ordered PdCu-based nanoparticles (NPs) with composition control from PdCu to PdCuNi and PtCuCo.Under the dual tuning on the composition and intermetallic phase,the ordered PdCuCo NPs exhibit better activity and much enhanced stability for ORR and ethanol-oxidation reaction (EOR)than those of disordered PdCuM NPs,the commercial Pt/Cand Pd/C catalysts.The density functional theory (DFT)calculations reveal that themore » improved ORR activity on the PdCuM NPs stems from the catalytically active hollow sites arising from the ligand effect and the compressive strain on thePd surface owing to the smaller atomic size of Cu, Co,and Ni.« less

Three-dimensional mapping of the lateral ventricles in autism

PubMed Central

Vidal, Christine N.; Nicolsonln, Rob; Boire, Jean-Yves; Barra, Vincent; DeVito, Timothy J.; Hayashi, Kiralee M.; Geaga, Jennifer A.; Drost, Dick J.; Williamson, Peter C.; Rajakumar, Nagalingam; Toga, Arthur W.; Thompson, Paul M.

2009-01-01

In this study, a computational mapping technique was used to examine the three-dimensional profile of the lateral ventricles in autism. T1-weighted three-dimensional magnetic resonance images of the brain were acquired from 20 males with autism (age: 10.1 ± 3.5 years) and 22 male control subjects (age: 10.7 ± 2.5 years). The lateral ventricles were delineated manually and ventricular volumes were compared between the two groups. Ventricular traces were also converted into statistical three-dimensional maps, based on anatomical surface meshes. These maps were used to visualize regional morphological differences in the thickness of the lateral ventricles between patients and controls. Although ventricular volumes measured using traditional methods did not differ significantly between groups, statistical surface maps revealed subtle, highly localized reductions in ventricular size in patients with autism in the left frontal and occipital horns. These localized reductions in the lateral ventricles may result from exaggerated brain growth early in life. PMID:18502618

A novel method for synthesis of phosphomolybdic acid-modified Pd/C catalysts for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Zhu, Mingyuan; Gao, Xiaoling; Luo, Guangqin; Dai, Bin

2013-03-01

This manuscript reports a convenient method for immobilizing phosphomolybdic acid (HPMo) on polyaniline (PAN-) functionalized carbon supports. The obtained HPMo-PAN-C sample is used as the support to prepare a Pd/HPMo-PAN-C catalyst. The samples are characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and X-ray diffraction analysis. The results suggest that HPMo retains its Keggin structure and that the presence of HPMo reduces the average particle size of the Pd nano-particles in the obtained Pd/HPMo-PAN-C catalyst. Electro-chemical measurements in 0.5 M HClO4 solution reveal that the Pd/HPMo-PAN-C catalyst has higher catalytic activity for oxygen reduction reactions than does a Pd/C catalyst prepared using a similar procedure. The stability of the Pd/HPMo-PAN-C catalyst is evaluated by multiple-cycle voltammetry techniques; the mass catalytic activity decreases by only 10% after 100 scanning cycles.

Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Manish; Devi, Pooja; Shivling, V. D.

2017-08-01

Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

Non linear optical investigations of silver nanoparticles synthesised by curcumin reduction

NASA Astrophysics Data System (ADS)

Dhanya, N. P.

2017-11-01

Metal nanoparticles have considerable applications in assorted fields like medicine, biology, photonics, metallurgy etc. Optical applications of Silver nanoparticles are of significant interest among researchers nowadays. In this paper, we report a single step chemical reduction of silver nanoparticles with Curcumin both as a reducing and stabilising agent at room temperature. Structural, plasmonic and non linear optical properties of the prepared nanoparticles are explored using Scanning Electron Microscope, Transmission Electron Microscope, UV absorption spectrometry, Spectroflurometry and Z scan. UV-Vis absorption studies affirm the Surface Plasmon Resonance (SPR) absorption and spectroflurometric studies announce the emission spectrum of the prepared silvernanoparticles at 520 nm. SEM and TEM images uphold the existence of uniform sized, spherical silvernanoparticles. Nonlinear optical studies are accomplished with the open aperture z scan technique in the nanosecond regime. The nonlinearity is in virtue of saturable absorption, two-photon absorption and excited state absorption. The marked nonlinearity and optical limiting of the Curcumin reduced silvernanoparticles enhances its photonic applications.

Preliminary noise tradeoff study of a Mach 2.7 cruise aircraft

NASA Technical Reports Server (NTRS)

Mascitti, V. R.; Maglieri, D. J. (Editor); Raney, J. P. (Editor)

1979-01-01

NASA computer codes in the areas of preliminary sizing and enroute performance, takeoff and landing performance, aircraft noise prediction, and economics were used in a preliminary noise tradeoff study for a Mach 2.7 design supersonic cruise concept. Aerodynamic configuration data were based on wind-tunnel model tests and related analyses. Aircraft structural characteristics and weight were based on advanced structural design methodologies, assuming conventional titanium technology. The most advanced noise prediction techniques available were used, and aircraft operating costs were estimated using accepted industry methods. The 4-engines cycles included in the study were based on assumed 1985 technology levels. Propulsion data was provided by aircraft manufacturers. Additional empirical data is needed to define both noise reduction features and other operating characteristics of all engine cycles under study. Data on VCE design parameters, coannular nozzle inverted flow noise reduction and advanced mechanical suppressors are urgently needed to reduce the present uncertainties in studies of this type.

Applying machine learning classification techniques to automate sky object cataloguing

NASA Astrophysics Data System (ADS)

Fayyad, Usama M.; Doyle, Richard J.; Weir, W. Nick; Djorgovski, Stanislav

1993-08-01

We describe the application of an Artificial Intelligence machine learning techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Mt. Palomar Northern Sky Survey is nearly completed. This survey provides comprehensive coverage of the northern celestial hemisphere in the form of photographic plates. The plates are being transformed into digitized images whose quality will probably not be surpassed in the next ten to twenty years. The images are expected to contain on the order of 107 galaxies and 108 stars. Astronomers wish to determine which of these sky objects belong to various classes of galaxies and stars. Unfortunately, the size of this data set precludes analysis in an exclusively manual fashion. Our approach is to develop a software system which integrates the functions of independently developed techniques for image processing and data classification. Digitized sky images are passed through image processing routines to identify sky objects and to extract a set of features for each object. These routines are used to help select a useful set of attributes for classifying sky objects. Then GID3 (Generalized ID3) and O-B Tree, two inductive learning techniques, learns classification decision trees from examples. These classifiers will then be applied to new data. These developmnent process is highly interactive, with astronomer input playing a vital role. Astronomers refine the feature set used to construct sky object descriptions, and evaluate the performance of the automated classification technique on new data. This paper gives an overview of the machine learning techniques with an emphasis on their general applicability, describes the details of our specific application, and reports the initial encouraging results. The results indicate that our machine learning approach is well-suited to the problem. The primary benefit of the approach is increased data reduction throughput. Another benefit is consistency of classification. The classification rules which are the product of the inductive learning techniques will form an objective, examinable basis for classifying sky objects. A final, not to be underestimated benefit is that astronomers will be freed from the tedium of an intensely visual task to pursue more challenging analysis and interpretation problems based on automatically catalogued data.

Detection and Sizing of Fatigue Cracks in Steel Welds with Advanced Eddy Current Techniques

NASA Astrophysics Data System (ADS)

Todorov, E. I.; Mohr, W. C.; Lozev, M. G.

2008-02-01

Butt-welded specimens were fatigued to produce cracks in the weld heat-affected zone. Advanced eddy current (AEC) techniques were used to detect and size the cracks through a coating. AEC results were compared with magnetic particle and phased-array ultrasonic techniques. Validation through destructive crack measurements was also conducted. Factors such as geometry, surface treatment, and crack tightness interfered with depth sizing. AEC inspection techniques have the potential of providing more accurate and complete sizing flaw data for manufacturing and in-service inspections.

Size and morphology controlled NiSe nanoparticles as efficient catalyst for the reduction reactions

NASA Astrophysics Data System (ADS)

Subbarao, Udumula; Marakatti, Vijaykumar S.; Amshumali, Mungalimane K.; Loukya, B.; Singh, Dheeraj Kumar; Datta, Ranjan; Peter, Sebastian C.

2016-12-01

Facile and efficient ball milling and polyol methods were employed for the synthesis of nickel selenide (NiSe) nanoparticle. The particle size of the NiSe nanoparticle has been controlled mechanically by varying the ball size in the milling process. The role of the surfactants in the formation of various morphologies was studied. The compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The efficiency of the NiSe nanoparticle as a catalyst was tested for the reduction of para-nitroaniline (PNA) to para-phenyldiamine (PPD) and para-nitrophenol (PNP) to para-aminophenol (PAP) using NaBH4 as the reducing agent. Particle size, morphology and the presence of surfactant played a crucial role in the reduction process.

Sizing of patent ductus arteriosus in adults for transcatheter closure using the balloon pull-through technique.

PubMed

Shafi, Nabil A; Singh, Gagan D; Smith, Thomas W; Rogers, Jason H

2018-05-01

To describe a novel balloon sizing technique used during adult transcatheter patent ductus arteriosus (PDA) closure. In addition, to determine the clinical and procedural outcomes in six patients who underwent PDA balloon sizing with subsequent deployment of a PDA occluder device. Transcatheter PDA closure in adults has excellent safety and procedural outcomes. However, PDA sizing in adults can be challenging due to variable defect size, high flow state, or anatomical complexity. We describe a series of six cases where the balloon- pull through technique was successfully performed for PDA sizing prior to transcatheter closure. Consecutive adult patients undergoing adult PDA closure at our institution were studied retrospectively. A partially inflated sizing balloon was pulled through the defect from the aorta into the pulmonary artery and the balloon waist diameter was measured. Procedural success and clinical outcomes were obtained. Six adult patients underwent successful balloon pull-through technique for PDA sizing during transcatheter PDA closure, since conventional angiography often gave suboptimal opacification of the defect. All PDAs were treated with closure devices based on balloon PDA sizing with complete closure and no complications. In three patients that underwent preprocedure computed tomography, the balloon size matched the CT derived measurements. The balloon pull-through technique for PDA sizing is a safe and accurate sizing modality in adults undergoing transcatheter PDA closure. © 2017 Wiley Periodicals, Inc.

Long-term acclimatory response to excess excitation energy: evidence for a role of hydrogen peroxide in the regulation of photosystem II antenna size.

PubMed

Borisova-Mubarakshina, Maria M; Ivanov, Boris N; Vetoshkina, Daria V; Lubimov, Valeriy Y; Fedorchuk, Tatyana P; Naydov, Ilya A; Kozuleva, Marina A; Rudenko, Natalia N; Dall'Osto, Luca; Cazzaniga, Stefano; Bassi, Roberto

2015-12-01

Higher plants possess the ability to trigger a long-term acclimatory response to different environmental light conditions through the regulation of the light-harvesting antenna size of photosystem II. The present study provides an insight into the molecular nature of the signal which initiates the high light-mediated response of a reduction in antenna size. Using barley (Hordeum vulgare) plants, it is shown (i) that the light-harvesting antenna size is not reduced in high light with a low hydrogen peroxide content in the leaves; and (ii) that a decrease in the antenna size is observed in low light in the presence of an elevated concentration of hydrogen peroxide in the leaves. In particular, it has been demonstrated that the ability to reduce the antenna size of photosystem II in high light is restricted to photosynthetic apparatus with a reduced level of the plastoquinone pool and with a low hydrogen peroxide content. Conversely, the reduction of antenna size in low light is induced in photosynthetic apparatus possessing elevated hydrogen peroxide even when the reduction level of the plastoquinone pool is low. Hydrogen peroxide affects the relative abundance of the antenna proteins that modulate the antenna size of photosystem II through a down-regulation of the corresponding lhcb mRNA levels. This work shows that hydrogen peroxide contributes to triggering the photosynthetic apparatus response for the reduction of the antenna size of photosystem II by being the molecular signal for the long-term acclimation of plants to high light. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Interplay among Coating Thickness, Strip Size, and Thermal and Solidification Characteristics in A356 Lost Foam Casting Alloy

NASA Astrophysics Data System (ADS)

Shabestari, S. G.; Divandari, M.; Ghoncheh, M. H.; Jamali, V.

2017-10-01

The aim of this research was evaluation of the solidification parameters of A356 alloy, e.g., dendrite arm spacing (DAS), correlation between cooling rate (CR) and DAS, hot tearing, and microstructural analysis at different coating thicknesses and strip sizes during the lost foam casting process (LFC). To achieve this goal, the DAS was measured at six coating thicknesses and six different strip sizes. In addition, thermal characteristics, such as the CR, temperatures of start and finish points of solidification, recalescence undercooling, and hot tearing susceptibility (HCSC), at five coating thicknesses were recognized from the cooling curves and their first derivative and the solid fraction curves, which have been plotted through the thermal analysis technique. The pouring temperature and strip size were fixed at 1063 K (790 °C) and 12 mm, respectively. Besides, to derive a numerical equation to predict the CR by measuring the DAS in this alloy, a microstructural evaluation was carried out on samples cast through 12-mm strip size. The results showed that both coating thickness and strip size had similar influences on the DAS, in which, by retaining one parameter at a constant value and simultaneous enhancement in the other parameter, the DAS increased significantly. Furthermore, at thinner coating layer, the higher amount of the CR was observed, which caused reduction in the temperatures of both the start and finish points of solidification. Also, increasing the CR caused a nonlinear increase in both the recalescence undercooling and the HCSC.

Influence of size-fractioning techniques on concentrations of selected trace metals in bottom materials from two streams in northeastern Ohio

USGS Publications Warehouse

Koltun, G.F.; Helsel, Dennis R.

1986-01-01

Identical stream-bottom material samples, when fractioned to the same size by different techniques, may contain significantly different trace-metal concentrations. Precision of techniques also may differ, which could affect the ability to discriminate between size-fractioned bottom-material samples having different metal concentrations. Bottom-material samples fractioned to less than 0.020 millimeters by means of three common techniques (air elutriation, sieving, and settling) were analyzed for six trace metals to determine whether the technique used to obtain the desired particle-size fraction affects the ability to discriminate between bottom materials having different trace-metal concentrations. In addition, this study attempts to assess whether median trace-metal concentrations in size-fractioned bottom materials of identical origin differ depending on the size-fractioning technique used. Finally, this study evaluates the efficiency of the three size-fractioning techniques in terms of time, expense, and effort involved. Bottom-material samples were collected at two sites in northeastern Ohio: One is located in an undeveloped forested basin, and the other is located in a basin having a mixture of industrial and surface-mining land uses. The sites were selected for their close physical proximity, similar contributing drainage areas, and the likelihood that trace-metal concentrations in the bottom materials would be significantly different. Statistically significant differences in the concentrations of trace metals were detected between bottom-material samples collected at the two sites when the samples had been size-fractioned by means of air elutriation or sieving. Statistical analyses of samples that had been size fractioned by settling in native water were not measurably different in any of the six trace metals analyzed. Results of multiple comparison tests suggest that differences related to size-fractioning technique were evident in median copper, lead, and iron concentrations. Technique-related differences in copper concentrations most likely resulted from contamination of air-elutriated samples by a feed tip on the elutriator apparatus. No technique-related differences were observed in chromium, manganese, or zinc concentrations. Although air elutriation was the most expensive sizefractioning technique investigated, samples fractioned by this technique appeared to provide a superior level of discrimination between metal concentrations present in the bottom materials of the two sites. Sieving was an adequate lower-cost but more laborintensive alternative.

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

NASA Astrophysics Data System (ADS)

Stehlik, Stepan; Varga, Marian; Ledinsky, Martin; Miliaieva, Daria; Kozak, Halyna; Skakalova, Viera; Mangler, Clemens; Pennycook, Timothy J.; Meyer, Jannik C.; Kromka, Alexander; Rezek, Bohuslav

2016-12-01

Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous.

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

PubMed Central

Stehlik, Stepan; Varga, Marian; Ledinsky, Martin; Miliaieva, Daria; Kozak, Halyna; Skakalova, Viera; Mangler, Clemens; Pennycook, Timothy J.; Meyer, Jannik C.; Kromka, Alexander; Rezek, Bohuslav

2016-01-01

Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous. PMID:27910924

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution.

PubMed

Stehlik, Stepan; Varga, Marian; Ledinsky, Martin; Miliaieva, Daria; Kozak, Halyna; Skakalova, Viera; Mangler, Clemens; Pennycook, Timothy J; Meyer, Jannik C; Kromka, Alexander; Rezek, Bohuslav

2016-12-02

Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous.

Egg size and laying order of snowy egrets, great egrets, and black-crowned night-herons

USGS Publications Warehouse

Custer, T.W.; Frederick, P.C.

1990-01-01

The nesting biology of the family Ardeidae (bitterns, herons, and egrets) has been intensively studied (e.g., Owen 1960, Milstein et al. 1970, Werschkul 1979), but egg size in relation to laying order bas not received attention. The last egg laid in gull and tern clutches is generally smaller than preceding eggs (e.g., Parsons 1970, Nisbet 1978). The relative size of the final egg in a clutch decreases with increased body size among bird species and this relationship may be correlated with an increased brood-reduction strategy (Slagsvold et al. 1984). Relative egg size could be an important component to brood reduction, because egg size can affect subsequent survival of young (Parsons 1970, Nisbet 1978, Lundberg and Vaisanen 1979).

Reduction-responsive PEtOz-SS-PCL micelle with tailored size to overcome blood-brain barrier and enhance doxorubicin antiglioma effect.

PubMed

Li, Yuling; Baiyang, Li; Leran, Bu; Zhen, Wang; Yandong, Xie; Baixiang, Du; Dandan, Zhu; Yufu, Zhu; Jun, Liang; Rutong, Yu; Hongmei, Liu

2017-11-01

A series of novel reduction-responsive micelles with tailored size were designed and prepared to release doxorubicin (DOX) for treating glioma, which were developed based on amphiphilic block copolymer poly (2-ethyl-2-oxazoline)-b-poly (ε-caprolactone) (PEtOz-SS-PCL) and the micelle size could be regulated by designing the polymer structure. The DOX-loaded PEtOz-SS-PCL micelles had small size and rapid drug release in reductive intracellular environments. Biodistribution and in vivo imaging studies in C6 glioma mice tumor model showed that DOX loaded PEtOz-SS-PCL43 micelles with the smallest size had superior accumulation and fast drug release in tumor sites. In vivo antitumor activity demonstrated that DOX-loaded PEtOz-SS-PCL43 micelles improved antitumor efficacy in contrast to PEtOz-SS-PCL micelles with larger size toward the orthotopic C6-Luci cells-bearing mice. This study shows great potential in tailoring the micelle size and introducing the responsive bonds or compartment for intracellular drug delivery and release in glioma treatment by designing the architecture of the polymer.

Separation of milk fat globules via microfiltration: Effect of diafiltration media and opportunities for stream valorization.

PubMed

Jukkola, A; Partanen, R; Rojas, O J; Heino, A

2016-11-01

Milk fat globule membranes (MFGM) sourced in buttermilk have gained recent interest given their nutritional value and functional properties. However, production of isolated MFGM has been challenging given their size similarity with casein micelles, which limits attempts toward fractionation by size exclusion techniques. Therefore, the hypothesis underpinning this study is that the removal of proteins from cream before butter-making facilitates MFGM isolation. As such, milk fat globules were separated from raw whole milk via microfiltration (1.4-µm pore diameter and 0.005-m 2 filtration surface area) by using 3 diafiltration media; namely, skim milk ultrafiltration permeate, saline, and water. Their effects on the stability of the milk fat globules and protein permeation was elucidated. Whereas a substantial reduction in protein concentration was achieved with all diafiltration media (~90% reduction), water and saline produced negligible membrane fouling with better filtration performance. Moreover, diafiltration with skim milk ultrafiltration permeate exhibited reduced permeate flux. Colloidal stability of the resultant milk decreased with all diafiltration solutions due to changing composition and reduced apparent viscosity. Overall, microfiltration was found to be an efficient method for separation of milk fat globules from whole milk, leading to increased MFGM fragment concentration in buttermilk dry matter, thus making it more suitable for industrial utilization. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Compression of high-density EMG signals for trapezius and gastrocnemius muscles.

PubMed

Itiki, Cinthia; Furuie, Sergio S; Merletti, Roberto

2014-03-10

New technologies for data transmission and multi-electrode arrays increased the demand for compressing high-density electromyography (HD EMG) signals. This article aims the compression of HD EMG signals recorded by two-dimensional electrode matrices at different muscle-contraction forces. It also shows methodological aspects of compressing HD EMG signals for non-pinnate (upper trapezius) and pinnate (medial gastrocnemius) muscles, using image compression techniques. HD EMG signals were placed in image rows, according to two distinct electrode orders: parallel and perpendicular to the muscle longitudinal axis. For the lossless case, the images obtained from single-differential signals as well as their differences in time were compressed. For the lossy algorithm, the images associated to the recorded monopolar or single-differential signals were compressed for different compression levels. Lossless compression provided up to 59.3% file-size reduction (FSR), with lower contraction forces associated to higher FSR. For lossy compression, a 90.8% reduction on the file size was attained, while keeping the signal-to-noise ratio (SNR) at 21.19 dB. For a similar FSR, higher contraction forces corresponded to higher SNR CONCLUSIONS: The computation of signal differences in time improves the performance of lossless compression while the selection of signals in the transversal order improves the lossy compression of HD EMG, for both pinnate and non-pinnate muscles.

Compression of high-density EMG signals for trapezius and gastrocnemius muscles

PubMed Central

2014-01-01

Background New technologies for data transmission and multi-electrode arrays increased the demand for compressing high-density electromyography (HD EMG) signals. This article aims the compression of HD EMG signals recorded by two-dimensional electrode matrices at different muscle-contraction forces. It also shows methodological aspects of compressing HD EMG signals for non-pinnate (upper trapezius) and pinnate (medial gastrocnemius) muscles, using image compression techniques. Methods HD EMG signals were placed in image rows, according to two distinct electrode orders: parallel and perpendicular to the muscle longitudinal axis. For the lossless case, the images obtained from single-differential signals as well as their differences in time were compressed. For the lossy algorithm, the images associated to the recorded monopolar or single-differential signals were compressed for different compression levels. Results Lossless compression provided up to 59.3% file-size reduction (FSR), with lower contraction forces associated to higher FSR. For lossy compression, a 90.8% reduction on the file size was attained, while keeping the signal-to-noise ratio (SNR) at 21.19 dB. For a similar FSR, higher contraction forces corresponded to higher SNR Conclusions The computation of signal differences in time improves the performance of lossless compression while the selection of signals in the transversal order improves the lossy compression of HD EMG, for both pinnate and non-pinnate muscles. PMID:24612604

Size and morphology controlled NiSe nanoparticles as efficient catalyst for the reduction reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subbarao, Udumula; Marakatti, Vijaykumar S.; Amshumali, Mungalimane K.

Facile and efficient ball milling and polyol methods were employed for the synthesis of nickel selenide (NiSe) nanoparticle. The particle size of the NiSe nanoparticle has been controlled mechanically by varying the ball size in the milling process. The role of the surfactants in the formation of various morphologies was studied. The compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The efficiency of the NiSe nanoparticle as a catalyst was tested for the reduction of para-nitroaniline (PNA) to para-phenyldiamine (PPD) and para-nitrophenol (PNP) to para-aminophenol (PAP)more » using NaBH{sub 4} as the reducing agent. Particle size, morphology and the presence of surfactant played a crucial role in the reduction process. - Graphical abstract: NiSe nanoparticles in different size and morphology were synthesized using facile ball milling and polyol methods. Particle size, morphology and the presence of surfactant in these materials played a crucial role in the hydrogenation of PNA and PNP. - Highlights: • NiSe nanoparticles synthesized using ball milling and solution phase methods. • NiSe nanoparticle is an efficient catalyst for the reduction of PNA and PNP. • NiSe is found to be better than the best reported noble metal catalysts.« less

Effective implementation of the weak Galerkin finite element methods for the biharmonic equation

DOE PAGES

Mu, Lin; Wang, Junping; Ye, Xiu

2017-07-06

The weak Galerkin (WG) methods have been introduced in [11, 12, 17] for solving the biharmonic equation. The purpose of this paper is to develop an algorithm to implement the WG methods effectively. This can be achieved by eliminating local unknowns to obtain a global system with significant reduction of size. In fact this reduced global system is equivalent to the Schur complements of the WG methods. The unknowns of the Schur complement of the WG method are those defined on the element boundaries. The equivalence of theWG method and its Schur complement is established. The numerical results demonstrate themore » effectiveness of this new implementation technique.« less

Orbital selective directional conductor in the two-orbital Hubbard model

DOE PAGES

Mukherjee, Anamitra; Patel, Niravkumar D.; Moreo, Adriana; ...

2016-02-29

Recently, we employed a developed many-body technique that allows for the incorporation of thermal effects, the rich phase diagram of a two-dimensional two-orbital (degenerate d xz and d yz) Hubbard model is presented varying temperature and the repulsion U. The main result is the finding at intermediate U of an antiferromagnetic orbital selective state where an effective dimensional reduction renders one direction insulating and the other metallic. Possible realizations of this state are discussed. Additionally, we also study nematicity above the N eel temperature. After a careful finite-size scaling analysis, the nematicity temperature window appears to survive in the bulkmore » limit, although it is very narrow.« less

Effective implementation of the weak Galerkin finite element methods for the biharmonic equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mu, Lin; Wang, Junping; Ye, Xiu

The weak Galerkin (WG) methods have been introduced in [11, 12, 17] for solving the biharmonic equation. The purpose of this paper is to develop an algorithm to implement the WG methods effectively. This can be achieved by eliminating local unknowns to obtain a global system with significant reduction of size. In fact this reduced global system is equivalent to the Schur complements of the WG methods. The unknowns of the Schur complement of the WG method are those defined on the element boundaries. The equivalence of theWG method and its Schur complement is established. The numerical results demonstrate themore » effectiveness of this new implementation technique.« less

Antibacterial and photocatalytic degradation efficacy of silver nanoparticles biosynthesized using Cordia dichotoma leaf extract

NASA Astrophysics Data System (ADS)

Mankamna Kumari, R.; Thapa, Nikita; Gupta, Nidhi; Kumar, Ajeet; Nimesh, Surendra

2016-12-01

The present study focuses on the biosynthesis of silver nanoparticles (AgNPs) along with its antibacterial and photocatalytic activity. The AgNPs were synthesized using Cordia dichotoma leaf extract and were characterized using UV-vis spectroscopy to determine the formation of AgNPs. FTIR was done to discern biomolecules responsible for reduction and capping of the synthesized nanoparticles. Further, DLS technique was performed to examine its hydrodynamic diameter, followed by SEM, TEM and XRD to determine its size, morphology and crystalline structure. Later, these AgNPs were studied for their potential role in antibacterial activity and photocatalytic degradation of azo dyes such as methylene blue and Congo red.

Synthesis of three-dimensionally ordered macro-/mesoporous Pt with high electrocatalytic activity by a dual-templating approach

NASA Astrophysics Data System (ADS)

Zhang, Chengwei; Yang, Hui; Sun, Tingting; Shan, Nannan; Chen, Jianfeng; Xu, Lianbin; Yan, Yushan

2014-01-01

Three dimensionally ordered macro-/mesoporous (3DOM/m) Pt catalysts are fabricated by chemical reduction employing a dual-templating synthesis approach combining both colloidal crystal (opal) templating (hard-templating) and lyotropic liquid crystal templating (soft-templating) techniques. The macropore walls of the prepared 3DOM/m Pt exhibit a uniform mesoporous structure composed of polycrystalline Pt nanoparticles. Both the size of the mesopores and Pt nanocrystallites are in the range of 3-5 nm. The 3DOM/m Pt catalyst shows a larger electrochemically active surface area (ECSA), and higher catalytic activity as well as better poisoning tolerance for methanol oxidation reaction (MOR) than the commercial Pt black catalyst.

Class Size Reduction or Rapid Formative Assessment?: A Comparison of Cost-Effectiveness

ERIC Educational Resources Information Center

Yeh, Stuart S.

2009-01-01

The cost-effectiveness of class size reduction (CSR) was compared with the cost-effectiveness of rapid formative assessment, a promising alternative for raising student achievement. Drawing upon existing meta-analyses of the effects of student-teacher ratio, evaluations of CSR in Tennessee, California, and Wisconsin, and RAND cost estimates, CSR…

Early Implementation of the Class Size Reduction Initiative.

ERIC Educational Resources Information Center

Illig, David C.

A survey of school districts was conducted to determine the initial progress and problems associated with the 1997 Class Size Reduction (CSR) Initiative. Data reveal that most school districts had enough space for smaller classes for at least two grade levels; small school districts were much less likely to report space constraints. The CSR did…

Class Size Reduction in a Large Urban School District: A Mixed Methodology Evaluation Research Study.

ERIC Educational Resources Information Center

Munoz, Marco A.

This study evaluated the Class Size Reduction (CSR) program in 34 elementary schools in Kentucky's Jefferson County Public Schools. The CSR program is a federal initiative to help elementary schools improve student learning by hiring additional teachers. Qualitative data were collected using unstructured interviews, site observations, and document…

Class Size Reduction: Great Hopes, Great Challenges. Policy Brief.

ERIC Educational Resources Information Center

WestEd, San Francisco, CA.

This policy brief examines the benefits and the challenges that accompany class-size reduction (CSR). It suggests that when designing CSR programs, states should carefully assess specific circumstances in their schools as they adopt or modify CSR efforts to avoid the unintended consequences that some programs have experienced. Some of the…

Oil sorption by lignocellulosic fibers

Treesearch

Beom-Goo Lee; James S. Han; Roger M. Rowell

1999-01-01

The oil sorption capacities of cotton fiber, kenaf bast fiber, kenaf core fiber, and moss fiber were compared after refining, extraction, and reduction in particle sizes. The tests were conducted on diesel oil in a pure form. Cotton fiber showed the highest capacity, followed by kenaf core and bast fibers. Wetting, extraction, and reduction in particle size all...

Woody biomass pretreatment for cellulosic ethanol production : technology and energy consumption evaluation

Treesearch

Junyong Zhu; X.J. Pan

2010-01-01

This review presents a comprehensive discussion of the key technical issues in woody biomass pretreatment: barriers to efficient cellulose saccharification, pretreatment energy consumption, in particular energy consumed for wood-size reduction, and criteria to evaluate the performance of a pretreatment. A post-chemical pretreatment size-reduction approach is proposed...

The False Promise of Class-Size Reduction

ERIC Educational Resources Information Center

Chingos, Matthew M.

2011-01-01

Class-size reduction, or CSR, is enormously popular with parents, teachers, and the public in general. Many parents believe that their children will benefit from more individualized attention in a smaller class and many teachers find smaller classes easier to manage. The pupil-teacher ratio is an easy statistic for the public to monitor as a…

Evaluation of Clipping Based Iterative PAPR Reduction Techniques for FBMC Systems

PubMed Central

Kollár, Zsolt

2014-01-01

This paper investigates filter bankmulticarrier (FBMC), a multicarrier modulation technique exhibiting an extremely low adjacent channel leakage ratio (ACLR) compared to conventional orthogonal frequency division multiplexing (OFDM) technique. The low ACLR of the transmitted FBMC signal makes it especially favorable in cognitive radio applications, where strict requirements are posed on out-of-band radiation. Large dynamic range resulting in high peak-to-average power ratio (PAPR) is characteristic of all sorts of multicarrier signals. The advantageous spectral properties of the high-PAPR FBMC signal are significantly degraded if nonlinearities are present in the transceiver chain. Spectral regrowth may appear, causing harmful interference in the neighboring frequency bands. This paper presents novel clipping based PAPR reduction techniques, evaluated and compared by simulations and measurements, with an emphasis on spectral aspects. The paper gives an overall comparison of PAPR reduction techniques, focusing on the reduction of the dynamic range of FBMC signals without increasing out-of-band radiation. An overview is presented on transmitter oriented techniques employing baseband clipping, which can maintain the system performance with a desired bit error rate (BER). PMID:24558338

Reductive Augmentation of the Breast.

PubMed

Chasan, Paul E

2018-06-01

Although breast reduction surgery plays an invaluable role in the correction of macromastia, it almost always results in a breast lacking in upper pole fullness and/or roundness. We present a technique of breast reduction combined with augmentation termed "reductive augmentation" to solve this problem. The technique is also extremely useful for correcting breast asymmetry, as well as revising significant pseudoptosis in the patient who has previously undergone breast augmentation with or without mastopexy. An evolution of techniques has been used to create a breast with more upper pole fullness and anterior projection in those patients desiring a more round, higher-profile appearance. Reductive augmentation is a one-stage procedure in which a breast augmentation is immediately followed by a modified superomedial pedicle breast reduction. Often, the excision of breast tissue is greater than would normally be performed with breast reduction alone. Thirty-five patients underwent reductive augmentation, of which 12 were primary surgeries and 23 were revisions. There was an average tissue removal of 255 and 227 g, respectively, per breast for the primary and revision groups. Six of the reductive augmentations were performed for gross asymmetry. Fourteen patients had a previous mastopexy, and 3 patients had a previous breast reduction. The average follow-up was 26 months. Reductive augmentation is an effective one-stage method for achieving a more round-appearing breast with upper pole fullness both in primary breast reduction candidates and in revisionary breast surgery. This technique can also be applied to those patients with significant asymmetry. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of methylation-sensitive enzymes on the enrichment of genic SNPs and the degree of genome complexity reduction in a two-enzyme genotyping-by-sequencing (GBS) approach: a case study in oil palm (Elaeis guineensis).

PubMed

Pootakham, Wirulda; Sonthirod, Chutima; Naktang, Chaiwat; Jomchai, Nukoon; Sangsrakru, Duangjai; Tangphatsornruang, Sithichoke

2016-01-01

Advances in next generation sequencing have facilitated a large-scale single nucleotide polymorphism (SNP) discovery in many crop species. Genotyping-by-sequencing (GBS) approach couples next generation sequencing with genome complexity reduction techniques to simultaneously identify and genotype SNPs. Choice of enzymes used in GBS library preparation depends on several factors including the number of markers required, the desired level of multiplexing, and whether the enrichment of genic SNP is preferred. We evaluated various combinations of methylation-sensitive ( Aat II, Pst I, Msp I) and methylation-insensitive ( Sph I, Mse I) enzymes for their effectiveness in genome complexity reduction and enrichment of genic SNPs. We discovered that the use of two methylation-sensitive enzymes effectively reduced genome complexity and did not require a size selection step. On the contrary, the genome coverage of libraries constructed with methylation-insensitive enzymes was quite high, and the additional size selection step may be required to increase the overall read depth. We also demonstrated the effectiveness of methylation-sensitive enzymes in enriching for SNPs located in genic regions. When two methylation-insensitive enzymes were used, only 16% of SNPs identified were located in genes and 18% in the vicinity (± 5 kb) of the genic regions, while most SNPs resided in the intergenic regions. In contrast, a remarkable degree of enrichment was observed when two methylation-sensitive enzymes were employed. Almost two thirds of the SNPs were located either inside (32-36%) or in the vicinity (28-31%) of the genic regions. These results provide useful information to help researchers choose appropriate GBS enzymes in oil palm and other crop species.