A review of rapid prototyping techniques for tissue engineering purposes

Rapid prototyping (RP) is a common name for several techniques, which read in data from computer-aided design (CAD) drawings and manufacture automatically threedimensional objects layer-by-layer according to the virtual design. The utilization of RP in tissue engineering enables the production of three-dimensional scaffolds with complex geometries and very fine structures. Adding micro- and nanometer details into the scaffolds improves the mechanical properties of the scaffold and ensures better cell adhesion to the scaffold surface. Thus, tissue engineering constructs can be customized according to the data acquired from the medical scans to match the each patient’s individual needs. In addition RP enables the control of the scaffold porosity making it possible to fabricate applications with desired structural integrity. Unfortunately, every RP process has its own unique disadvantages in building tissue engineering scaffolds. Hence, the future research should be focused into the development of RP machines designed specifically for fabrication of tissue engineering scaffolds, although RP methods already can serve as a link between tissue and engineering.

Structure of upper-g(9/2)-shell nuclei and shape effect in the Ag-94 isomeric states

Using a shell model which is capable of describing the spectra of upper g(9/2)-shell nuclei close to the N = Z line, we study the structure of two isomeric states 7(+) and 21(+) in the odd-odd N = Z nucleus Ag-94. It is found that both isomeric states exhibit a large collectivity. The 7(+) state is oblately deformed, and is suggested to be a shape isomer in nature. The 21(+) state becomes isomeric because of level inversion of the 19(+) and 21(+) states due to core excitations across the N = Z = 50 shell gap. Calculation of spectroscopic quadrupole moment indicates clearly an enhancement in these states due to the core excitations. However, the present shell model calculation that produces the 19(+)-21(+) level inversion cannot accept the large-deformation picture of Mukha et al.

beta-Delayed proton decays in the rare-earth region near drip line

The history of experimental study on beta-delayed proton decays in the rare-earth region was simply reviewed. The physical results of the beta-delayed proton decays obtained at IMP, Lanzhou over the last 10 years were summarized, mainly including the first observation of 9 new beta-delayed proton precursors along the odd-Z proton drip line and the new data for 2 waiting-point nuclei in the rp-process. The results were compared and discussed with different nuclear model calculations. Finally, the perspective in near future was briefly introduced.

A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe) The detector has been successfully used in an experiment to measure the masses of the N approximate to Z approximate to 33 nuclides near the proton drip-line Of particular interest is the mass of As-65 A maximum detection efficiency of 70% and a time resolution of 118 +/- 8 Ps (FWHM) have been achieved in the experiment The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied The potential of APH for Z identification has been discussed (C) 2010 Elsevier B V All rights reserved

Slicing issues in CAD translation to STL in rapid prototyping

The rapid prototyping (RP) process is being used widely with great potential for rapid manufacturing of functional parts. The RP process involves translation of the CAD file to STL format followed by slicing of the model into multiple horizontal layers, each of which is reproduced physically in making the prototype. The thickness of the resulting slices has a profound effect on the surface finish and build time of the prototype. The purpose of this paper is to show the effects of slice thickness on the surface finish, layering error, and build time of a prototype, as well as to show how an efficient STL file can be developed. Three objects were modeled and STL files were generated. One STL file for each object was sliced using different slice thicknesses, and the build times were obtained. Screenshots were used to show the slicing effect on layering error and surface finish and to demonstrate the means to a more efficient STL file. From the results, it is clear that the surface finish and build time are important factors that are affected by slice thickness

Reductive photocatalysis and smart inks

Semiconductor-sensitised photocatalysis is a well-established and growing area of research, innovation and commercialisation; the latter being mostly limited to the use of TiO2 as the semiconductor. Most of the work on semiconductor photocatalytic systems uses oxygen as the electron acceptor and explores a wide range of electron donors; such systems can be considered to be examples of oxidative photocatalysis, OP. OP underpins most current examples of commercial self-cleaning materials, such as: glass, tiles, concrete, paint and fabrics. OP, and its myriad of applications, have been reviewed extensively over the years both in this journal and elsewhere. However, the ability of TiO2, and other semiconductor sensitisers, to promote reductive photocatalysis, RP, especially of dyes, is significant and, although less well-known, is of growing importance. In such systems, the source of the electrons is some easily oxidised species, such as glycerol. One recent, significant example of a RP process is with respect to photocatalyst activity indicator inks. paiis, which provide a measure of the activity of a photocatalytic film under test via the rate of change of colour of the dye in the ink coating due to irreversible RP. In contrast, by incorporating the semiconductor sensitiser in the ink, rather than outside it, it is possible to create an effective UV dosimeter, based on RP, which can be used as a sun-burn warning indicator. In the above examples the dye is reduced irreversibly, but when the photocatalyst in an ink is used to reversibly photoreduce a dye, a novel, colourimetric oxygen-sensitive indicator ink can be created, which has commercial potential in the food packaging industry. Finally, if no dye is present in the ink, and the semiconductor photocatalyst-loaded ink film coats an easily reduced substrate, such as a metal oxide film, then it can be used to reduce the latter and so, for example, clean up tarnished steel. The above are examples of smart inks, i.e. inks that are active and provide either dynamic information (such as UV dose or O2 level) or a useful function (such as tarnish removal), and all work via a RP process and are reviewed here

Mass measurements on neutron-deficient nuclides at SHIPTRAP and commissioning of a cryogenic narrow-band FT-ICR mass spectrometer

The dissertation presented here deals with high-precision Penning trap mass spectrometry on short-lived radionuclides. Owed to the ability of revealing all nucleonic interactions, mass measurements far off the line of ß-stability are expected to bring new insight to the current knowledge of nuclear properties and serve to test the predictive power of mass models and formulas. In nuclear astrophysics, atomic masses are fundamental parameters for the understanding of the synthesis of nuclei in the stellar environments. This thesis presents ten mass values of radionuclides around A = 90 interspersed in the predicted rp-process pathway. Six of them have been experimentally determined for the first time. The measurements have been carried out at the Penning-trap mass spectrometer SHIPTRAP using the destructive time-of-fligh ion-cyclotron-resonance (TOF-ICR) detection technique. Given the limited performance of the TOF-ICR detection when trying to investigate heavy/superheavy species with small production cross sections (σ< 1 μb), a new detection system is found to be necessary. Thus, the second part of this thesis deals with the commissioning of a cryogenic double-Penning trap system for the application of a highly-sensitive, narrow-band Fourier-transform ion-cyclotron-resonance (FT-ICR) detection technique. With the non-destructive FT-ICR detection method a single singly-charged trapped ion will provide the required information to determine its mass. First off-line tests of a new detector system based on a channeltron with an attached conversion dynode, of a cryogenic pumping barrier, to guarantee ultra-high vacuum conditions during mass determination, and of the detection electronics for the required single-ion sensitivity are reported.

Tractable nonparametric bayesian inference in poisson processes with Gaussian process intensities

The inhomogeneous Poisson process is a point process that has varying intensity across its domain (usually time or space). For nonparametric Bayesian modeling, the Gaussian process is a useful way to place a prior distribution on this intensity. The combination of a Poisson process and GP is known as a Gaussian Cox process, or doubly-stochastic Poisson process. Likelihood-based inference in these models requires an intractable integral over an infinite-dimensional random function. In this paper we present the first approach to Gaussian Cox processes in which it is possible to perform inference without introducing approximations or finitedimensional proxy distributions. We call our method the Sigmoidal Gaussian Cox Process, which uses a generative model for Poisson data to enable tractable inference via Markov chain Monte Carlo. We compare our methods to competing methods on synthetic data and apply it to several real-world data sets. Copyright 2009.

Tractable nonparametric Bayesian inference in Poisson processes with Gaussian process intensities

The inhomogeneous Poisson process is a point process that has varying intensity across its domain (usually time or space). For nonparametric Bayesian modeling, the Gaussian process is a useful way to place a prior distribution on this intensity. The combination of a Poisson process and GP is known as a Gaussian Cox process, or doubly-stochastic Poisson process. Likelihood-based inference in these models requires an intractable integral over an infinite-dimensional random function. In this paper we present the first approach to Gaussian Cox processes in which it is possible to perform inference without introducing approximations or finite-dimensional proxy distributions. We call our method the Sigmoidal Gaussian Cox Process, which uses a generative model for Poisson data to enable tractable inference via Markov chain Monte Carlo. We compare our methods to competing methods on synthetic data and apply it to several real-world data sets.

The Gaussian process density sampler

We present the Gaussian Process Density Sampler (GPDS), an exchangeable generative model for use in nonparametric Bayesian density estimation. Samples drawn from the GPDS are consistent with exact, independent samples from a fixed density function that is a transformation of a function drawn from a Gaussian process prior. Our formulation allows us to infer an unknown density from data using Markov chain Monte Carlo, which gives samples from the posterior distribution over density functions and from the predictive distribution on data space. We can also infer the hyperparameters of the Gaussian process. We compare this density modeling technique to several existing techniques on a toy problem and a skullreconstruction task.

Conversion process of the dominant electroluminescence mechanism in a molecularly doped organic light-emitting device with only electron trapping

In this work, the detailed conversion process of the dominant electroluminescence (EL) mechanism in a device with Eu(TTA)(3)phen (TTA=thenoyltrifluoroacetone, phen=1,10-phenanthroline) doped CBP (4,4(')-N,N-'-dicarbazole-biphenyl) film as the emitting layer was investigated by analyzing the evolution of carrier distribution on dye and host molecules with increasing voltage. Firstly, it was confirmed that only electrons can be trapped in Eu(TTA)(3)phen doped CBP. As a result, holes and electrons would be situated on CBP and Eu(TTA)(3)phen molecules, respectively, and thus creates an unbalanced carrier distribution on both dye and host molecules. With the help of EL and photoluminescence spectra, the distribution of holes and electrons on both Eu(TTA)(3)phen and CBP molecules was demonstrated to change gradually with increasing voltage. Therefore, the dominant EL mechanism in this device changes gradually from carrier trapping at relatively low voltage to Forster energy transfer at relatively high voltage.

Effect of solvent hydration and temperature in the deacidification process of sunflower oil using ethanol

This work presents liquid-liquid experimental data for systems composed of sunflower seed oil, ethanol and water from 10 to 60 degrees C. The influence of process variables (temperature (T) and water concentration in the solvent (W)) on both the solvent content present in the raffinate (S(RP)) and extract (S(EP)) phases and the partition of free fatty acids (k(2)) was evaluated using the response surface methodology, where flash calculations were performed for each trial using the UNIQUAC equation. Water content in the solvent was the most important factor on the responses of S(EP) and k(2). Additionally, statistical analysis showed that the S(RP) was predominantly affected by temperature factor for low water content in the solvent. (c) 2009 Elsevier Ltd. All rights reserved.

Improved 2D‐HPLC of red wine by incorporating pre‐process signal‐smoothing algorithms

Twomultidimensional HPLC separations of an Australian red wine are presented, >70% of the available separation space was used. A porous graphitic carbon (PGC) stationary phase was used as the first dimension in both separations with both RP core–shell and hydrophilic interaction chromatography fully porous columns used separately in the second dimension. To overcome peak analysis problems caused by signal noise and low detection limits, the data were pre-processed with penalised least-squares smoothing. The PGC × RP combination separated 85 peaks with a spreading angle of 71 and the PGC × hydrophilic interaction chromatography separated 207 peaks with a spreading angle of 80. Both 2D-HPLC steps were completed in 76 min using a comprehensive stop-and-go approach. A smoothing step was added to peak-picking processes and was able to greatly reduce the number of false peaks present due to noise in the chromatograms. The required thresholds were not able to ignore the noise because of the small magnitude of the peaks; 1874 peaks were located in the non-smoothed PGC × RP separation that reduced to 227 peaks after smoothing was included.

A participação da sociedade civil organizada na gestão do patrimônio cultural de Ribeirão Preto: o CONPPAC/RP

Pós-graduação em Serviço Social - FCHS