Setup Configurations Research Articles

Efficient UV detection of protein crystals enabled by fluorescence excitation at wavelengths longer than 300 nm

It is well known that most proteins and many other biomolecules fluoresce when illuminated with UV radiation, but it is also commonly accepted that utilizing this property to detect protein crystals in crystallization setups is limited by the opacity of the materials used to contain and seal them. For proteins, this fluorescence property arises primarily from the presence of tryptophan residues in the sequence. Studies of protein crystallization results in a variety of setup configurations show that the opacity of the containment hardware can be overcome at longer excitation wavelengths, where typical hardware materials are more transparent in the UV, by the use of a powerful UV-light source that is effective in excitation even though not at the maximum of the excitation response. The results show that under these circumstances UV evaluation of crystallization trials and detection of biomolecular crystals in them is not limited by the hardware used. It is similarly true that a deficiency in tryptophan or another fluorescent component that limits the use of UV light for these purposes can be effectively overcome by the addition of fluorescent prostheses that bind to the biomolecule under study. The measurements for these studies were made with a device consisting of a potent UV-light source and a detection system specially adapted (i) to be tunable via a motorized and software-controlled absorption-filter system and (ii) to convey the excitation light to the droplet or capillary hosting the crystallization experiment by quartz-fibre light guides.

Study of Variations of the Electrospinning Process

Electrospinning has been considered a straightforward way of producing nano and micro fibers. In this work we are analyzing variations of the conventional electrospinning process to better understand and explore the effect of electrostatic interactions. The variations we are investigating include the insertion of polymer inside the electric field keeping the capillary for polymer injection at a floating potential. In this way we are exploring different mechanisms of charge induction. Also, we are using different setup configurations including: same as electrospinning, parallel macro and micro electrodes. Image analysis reveals the occurrence of instabilities/oscillations of the polymer flow (caused by redistribution of charges) leading to the deposition of fibers and improving polymer flow directionality. Fiber orientation on the substrate can be obtained using parallel macro and micro electrodes.

SU-FF-T-227: A Method for Intra-Fractional Beam Range Control in Proton Therapy Treatment

Purpose: Range uncertainty in proton therapy is a recognized concern. For some treatment sites, e.g., prostate, liver/pancreas, beam range in patient may change daily due to variations in patient setup and anatomical configurations. We propose a strategy for intra‐fractional range control based on in‐vivo range verification and retroactive correction. Method and Materials: A protontreatment field contains a series of spread‐out Bragg peaks (SOBP) weighted to produce a dose distribution uniform in depth over the target volume. While the convention is to deliver all the peaks with their full weights in a single sequence, we want to split the delivery into two or more subsequences each containing only part of the weight for each peak. The first one or two subsequences can be used to detect the beam range in patient, and the remaining subsequences will be delivered with, if necessary, adjusted beam energies and weights to retroactively correct the overall beam range so that the total dose distribution for the treatment session is as prescribed for the target volume and critical organs nearby. Range detection can be achieved by point dose measurements and by manipulating the partial weights of the subsequences to “encode” the beam range information into the dose distributions. Specifically, “sloped” SOBP depth dose distributions were created and dose ratios between oppositely “sloped” subsequences were used to determine the water equivalent pathlengths to the dosimeter locations. Results: “Sloped” SOBP distributions were produced with sufficient accuracy in a passive‐scattering beam delivery system. Phantom tests with ion chamber showed millimeter accuracy in range determination. Treatment planning exercises were performed for prostate cases to illustrate the range control strategy. Conclusion: A method for intra‐fractional beam range control in protontreatment has been explored with encouraging results.

Oxygen transfer in membrane bioreactors treating synthetic greywater

Mass transfer coefficients (k La) were studied in two pilot scale membrane bioreactors (MBR) with different setup configurations treating 200 L/h of synthetic greywater with mixed liquor suspended solids' (MLSS) concentrations ranging from 4.7 to 19.5 g/L. Besides the MLSS concentration, mixed liquor volatile suspended solids (MLVSS), total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and anionic surfactants of the sludge were measured. Although the pilot plants differed essentially in their configurations and aeration systems, similar α-factors at the same MLSS concentration could be determined. A comparison of the results to the published values of other authors showed that not the MLSS concentration but rather the MLVSS concentration seems to be the decisive parameter which influences the oxygen transfer in activated sludge systems operating at a high sludge retention time (SRT).

Mode II Delamination Toughness in Glass Fiber-Reinforced Polymers with Bridging Fibers and Stitching Threads

This article presents results for mode II delamination resistance of fiber-reinforced polymers (FRP) using a recently developed internal notched flexure (INF) test. The study showed that the decrease of the compliance with the growth of delamination in the INF test was much less than that predicted by analytical or finite element analyses of the same configuration. The difference was mainly due to pronounced shear force interaction generated by bridging fibers and stitching threads between fracture surfaces. A new data-deducing method, named direct method with correction (DMC), was developed for establishing a delamination resistance curve (R-curve), which can take into account the effects of shear force interaction but does not require in situ measurement of crack growth length. The DMC was further examined using results from a series of INF tests with variation in test set-up configurations and types of glass fiber preform.

Sterilizing filtration—Principles and practice for successful scale-up to manufacturing

Filtration process design using micro-filtration membranes includes the proper sizing and scale-up of filtration units and requires an understanding of the effects of membrane fouling on filter capacity. This fouling is usually quantified by some fouling factor K. The filter capacity (related to surface area A) also impacts the rate of filtration which is usually quantified by the initial normalized flux through the filter J 0. For ideally scalable systems, the normalized flux J 0 should be the same for filtration across the same membranes with different surface area. Since fittings and device design can significantly affect filter resistance, scale-up factors must be taken into account in designing a scalable filtration step. In this manuscript we describe the principal approach and tools utilized to successfully transfer the sterile membrane filtration process for a pharmaceutical product from laboratory through pilot plant to manufacturing. Generalized models of pore fouling based on the standard blocking or complete blocking mechanisms are derived to simulate filtration of solutions at different filter set-up configurations using filters of different filter areas and construction. The analysis shows that specific resistance of filters resulting from differences in construction, and resistances of other flow details must also be considered in scale-up. Three different scales are compared to illustrate the application of the models to evaluation of filtration data and to the scale-up of filtration for a pharmaceutical solution. Millipore hydrophilic PVDF sterilizing filters were used at all scales. Scale-up criteria based on surface area (filter capacity) and flow rate (filtration duration) were employed at different scales. The case study results confirm that successful scale-up of filtration of pharmaceutical products requires understanding and correct prediction of both, the fouling characteristics (impacted mostly by properties and interactions between solution and membrane) and the flow characteristics (impacted by the filter construction and by the filtration system configuration).

Comparison of Fixed- and Moving-Vessel Flow Measurements with an aDp in a Large River

A comparison of three-dimensional flow velocity measurements, made with an acoustic Doppler profiler (aDp) from fixed and moving vessels at cross sections of the Paraná River, Argentina, was performed. The purpose was to design a rapid and reliable procedure for quantifying the velocity field, and related parameters such as bed shear velocity and the identification of secondary circulations, in large rivers using an aDp. The fixed-vessel measurements were performed over a period of 10min at three vertical profiles along two of the sections. These data were then compared with the results of ten moving-vessel repeat transects made at each of the sections, and which intersected the fixed-vessel sampling locations, using a number of different aDp setup configurations. From the velocity profiles obtained with both fixed- and moving-vessel measurements, total bed shear velocity values were computed by applying the law-of-the-wall. The results indicate there can be significant differences between velocities obtained using the moving-vessel method and fixed-vessel measurements averaged over 10min. These differences in horizontal velocity can be significantly reduced by averaging five, or more, moving-vessel transects, with corresponding shear velocities calculated from five-transect averages showing differences ranging between 10 and 15%, dependent on the aDp configuration. Location of the at-a-point vertical velocity profile in relation to large-scale bed roughness may also be an influential factor, and ideally the bed morphology should be quantified together with the aDp-derived velocities. When using the aDp to identify secondary flow cells, it was found that although one cross-section transect can provide a reasonable overall picture, an average of five cross sections is necessary to resolve the finer details of flow. The implications for applications that use moving-vessel techniques for measurement and analysis of three-dimensional flow structures, including secondary flows, are highlighted.

Laser ablation of copper based alloys by single and double pulse laser induced breakdown spectroscopy

Single and double pulse laser induced breakdown spectroscopy was applied to the analysis of copper based alloys samples, in order to investigate the material ablation process under two different experimental conditions. An Nd:YAG laser, emitting at the fundamental wavelength (1064 nm) for a fixed value of total energy with the same pulse width, has been used for both set-up configurations. Certified samples of copper based alloys were examined in order to investigate the effect of their different compositions on the ablation process efficiency. The craters produced by the laser on the samples surfaces were measured by a contact profilometer in order to evaluate the mass of ablated material. In this respect the differences in behaviour of the single and the double pulse ablation for Laser Induced Breakdown Spectroscopy (LIBS), respectively, have been considered. The dependence, under the same experimental conditions, of the LIBS background emission of the different ablated masses of the material has also been investigated, by looking for normalization algorithms for quantitative data reduction. The behaviour of some peculiar intensity ratios, suitable for building calibration curves, has been studied in order to evaluate the trend in fractionated evaporation on going from the single pulse to the double pulse technique.

A proposed semi-empirical method for 235U mass calibration of the active-well neutron coincidence counter

In this work, a proposed semi-empirical method for 235U mass calibration of the active-well neutron coincidence counter (AWCC) is presented. Samples of low enriched uranium oxide powder in form of cylinders were used to investigate and verify the validity of the method. The calibration process was carried out via two main steps. First, different experimental setup configurations (for the detector and samples) were modeled with the Monte Carlo multi-particle transport code MCNP-4B to calculate, numerically, fission rates in the nuclear material (NM) samples for each configuration. Second, the absolute efficiency of the detector for the real coincidence neutrons was measured using a standard 252Cf point source. The measured efficiency was combined with the calculated fission rates to estimate the real coincidence count rate of the detector due to NM for each setup configuration. A semi-empirical calibration curve relates the 235U mass content in each modeled setup configuration with its corresponding estimated count rate was constructed. The calibration curve was checked against experimental data to verify the proposed method. 235U masses estimated from the calibration curve were found to be in agreement with the measured values within the error limits. An accuracy of better than 7.2% was achieved with an average precision of about 4%.

Electrohydrodynamic atomization for biodegradable polymeric particle production

Electrohydrodynamic atomization (EHDA) has many applications such as electrospray ionization in mass spectroscopy, electrospray deposition of thin films, pharmaceutical productions, and polymeric particle fabrications for drug encapsulation. In the present study, EHDA was employed to produce biodegradable polymeric micro- and nanoparticles. The effects of processing parameters such as polymer concentration, flow rate, surfactants, organic salt, and setup configurations on the size and morphology of polymeric particles were investigated systematically. By changing the various processing parameters, controllable particle shape and size can be achieved. PLGA nanoparticles with size of around 250 nm can be obtained by using organic salts to increase the conductivity of the spraying solution even at a relatively high flow rate. A higher flow rate has the advantage of producing a stable cone spray and can be easily reproduced. Solid and porous particles can be fabricated using different experimental setups to control the organic solvent evaporation rate. Also, paclitaxel, a model antineoplastic drug, was encapsulated in polymeric particles which can be employed for controlled release applications. In short, EHDA is a promising technique to fabricate polymeric micro- or nanoparticles which can be used in drug delivery systems.

TAMIL: an integrated fixture design system for prismatic parts

In this paper, a fixture design system called TAMIL (Towards A Manufacturing Integration Link) is discussed. The focus of this paper is on an automated methodology to perform support and location design in an integrated manner. In the Preliminary Design phase, a preliminary analysis of the product geometry (shape and size), and topology (features & surfaces) is performed. In the subsequent phase, the machining set-up configurations and Support/Location aspects of fixture design are determined. In location design, the focus is to position a given workpiece correctly with respect to a machine tool by selecting the appropriate location surfaces or features and their respective modular locator elements. In support design, the most feasible support surfaces during machining are identified and the corresponding modular support elements are selected.

Stabilization of multi-inventory systems with uncertain demand and setups

In this paper, we consider different aspects of the problem of controlling a multi-inventory system in the presence of uncertain demand and setups. The demand is unknown but bounded in an assigned compact set. The control input is assumed to be constant in its operating regime and to incur setup whenever a variation of this regime is required. Both setup times and setup configurations are unknown. We provide necessary and sufficient stabilizability conditions which turn out to be the same in the case in which there are no setups. Stabilization can be achieved, provided that the planning horizon is large enough and a computable lower bound is given. We also face the problem of ultimately confining the state in an assigned constraint set and provide conditions on this set for the problem to be feasible. Furthermore, we consider the case in which the controls are quantized, as in the case of systems which work in a switching mode. Finally, we deal with the case in which multiple setups may happen during the planning horizon.

Pileup correction of microdosimetric spectra

Microdosimetric spectra were measured at the Fermilab neutron therapy facility using low pressure proportional counters operated in pulse mode. The neutron beam has a very low duty cycle (<0.1%) and consequently a high instantaneous dose rate which causes distortions of the microdosimetric spectra due to pulse pileup. The determination of undistorted spectra at this facility necessitated (i) the modified operation of the proton accelerator to reduce the instantaneous dose rate and (ii) the establishment of a computational procedure to correct the measured spectra for remaining pileup distortions. In support of the latter effort, two different pileup simulation algorithms using analytical and Monte-Carlo-based approaches were developed. While the analytical algorithm allows a detailed analysis of pileup processes it only treats two-pulse and three-pulse pileup and its validity is hence restricted. A Monte-Carlo-based pileup algorithm was developed that inherently treats all degrees of pileup. This algorithm can be used in an iterative manner to correct pileup distorted spectra. The pileup simulation and correction codes compared well with experimental data. A set of pileup distorted spectra that were collected under different setup configurations at the Fermilab facility were corrected for pileup. Analysis of the spectral variations between the spectra is consistent with findings reported in the literature.

Effect of Setup Configurations of Split Computer Keyboards on Wrist Angle

Alternative computer keyboards whose halves can be slanted toward each other can reduce a risk factor (ulnar deviation) for work-related musculoskeletal disorders (WMSDs) affecting the upper limbs. Two questions that computer keyboard operators face when using keyboards that can be separated into halves (split keyboards) are: (1) At what angle should the keyboard halves be opened? and (2) At what distance apart should the keyboard halves be placed? The objective of this study was to investigate the effects of the opening angle and separation distance between halves of a split keyboard on wrist ulnar deviation and typing efficiency. Eleven experienced computer keyboard operators participated in this study and used a split keyboard that was set up in a conventional (nonsplit) format and also in 3 alternative configurations: (1) centers of keyboard halves were separated at 20-cm distance, (2) keyboard halves were separated half of the distance of shoulder width, and (3) keyboard halves were separated at shoulder width distance. The 3 alternative configurations resulted in ulnar deviation of both wrists that were less than ulnar deviation from typing on a conventional setup. There were no differences in ulnar deviations among the 3 alternative configurations. The results of this research provide physical therapists and ergonomists with a set of configurations of a split keyboard that they can recommend to their patients or clients. All of the alternative configurations of the split keyboard are beneficial in promoting a neutral wrist position, which theoretically would decrease exposure to WMSDs such as tenosynovitis in the wrist and carpal tunnel syndrome.

Beam size and collimation effects in spectroscopic ellipsometry of transparent films with optical thickness inhomogeneity

In spectroscopic ellipsometry (SE) measurements of thin films with inhomogeneous optical thickness, the spot size of the probe beam on the sample surface is a highly critical parameter in the treatment of the experimental data. SE measurements were performed on transparent samples prepared by various techniques: plasma enhanced chemical vapor deposition of diamond film, spin-coated PMMA films and thermally grown SiO 2 film. The first two deposition techniques can produce films with inhomogeneous optical thickness. By comparing SE measurements using different set-up configurations, we demonstrate that a combination of lenses and small diaphragms is most suitable for minimizing the effects related to the optical thickness distribution and light beam divergence. In this way mistakes are avoided in extracting physical parameters from SE optical modeling of these films.

Optical losses characterization in channel waveguide through the photodeflection method

The photodeflection method applied to the propagation losses characterization in channel waveguides is discussed using two different set-up configurations. 3-D and 1-D models are presented in order to calculate the photodeflection angle. The effects on the measurement of any set-up misalignment are studied. Different ways for determining the propagation losses are shown. Comparison between theoretical and experimental results for Ti : LiNbO3 and a glass channel waveguide is also reported.

Performance of an optical stand-off control system for laser materials processing

This paper presents an experimental investigation into a high-bandwidth optical range sensor for laser materials processing stand-off control. Radiation from a low-power laser beam is focused onto a workpiece surface and light reflected from the surface is collected through a main lens and directed into an imaging lens which focuses the signal to two positions after being split by a beam splitter. The irradiances of the two beams are detected by photodiodes placed behind pinhole apertures positioned fore and aft of the two focal positions. A differential amplifier is used to generate an output signal that determines the magnitude and direction of any workpiece displacement. The system facilitates a measuring range of ±6 mm. A set of of experiments are performed and results are analysed for different setup configurations. The approximate range of instrument linearity is ±1 mm for the 75-mm focal length main less and ±2 mm for the 120-mm lens; in this linear range the optimal accuracy resolution is 1 μm. The system's effectiveness is controlling the stand-off distance of a laser cutting machine, and hence cut quality, is assessed.

Fundamental Insights into Part Family Scheduling: The Single Machine Case

ABSTRACTA simulation study was conducted to investigate the behavior of family scheduling procedures in a dynamic dispatching environment. Two scheduling rules that incorporate setup avoidance mechanisms (FCFS‐F and SPT‐F) and two that do not (FCFS and SPT) were applied to a single machine. The scheduling environment was varied by controlling several important factors: the machine utilization, the number of setup configurations (families), the size of the family setup times relative to the job run times, the frequency by which members of the part families were released for processing, and the distribution of job interarrival and job run times.The major results from the study are the following: (1) The degree of stability in the system is the most influential factor with respect to mean flow time and flow time variance. Under low variance service and interarrival time distributions, the impact of scheduling rule selection is minor. (2) Conversely, under unstable scheduling situations, family scheduling procedures can have a substantial impact. (3) Clear interaction effects are noticed between all factors. The environment most conducive to family scheduling is characterized by high resource utilization, low setup‐to‐run time ratio, few part families, and erratic job arrivals. (4) Under conditions favorable to family scheduling, setup avoiding procedures can be used to increase output while at the same time reduce the mean and variance of flow time. (5) The shortest processing time rule (SPT) performs well with respect to mean flow time when relative setup times are small. Overall, however, SPT‐F generates the lowest mean flow time while FCFS‐F produces the lowest flow time variance.This study shows that scheduling procedures that consider setups in their structure can outperform rules that do not under many different operating conditions. However, the magnitude of this advantage very much depends on the scheduling environment. The results also highlight the fact that it may be better to try to reshape the manufacturing environment than worry about selecting the correct scheduling rule. If the environment cannot be stabilized, then the choice of a setup avoiding procedure, allocation of families to machines, and setup reduction become important issues.