In-house Generator Research Articles

Virtual fabrication and computational simulation of asphalt concrete microstructure

This study presents the development and verification of an in-house microstructure generator that can be used to fabricate virtual, two-dimensional microstructures of asphalt mixtures. The proposed methodology takes advantage of a modern image analysis system, i.e. Aggregate Image Measurement System 2, to obtain geometric characteristics of real aggregate particles. During the generation process, images of real aggregates are stored in a database and further positioned in the virtual microstructures in a way that the gradation, area fraction and orientation of the virtual aggregate skeleton closely reproduce properties of real asphalt concrete samples fabricated in the laboratory. To demonstrate the capabilities of the generator, a microstructural analysis procedure used to quantify key volumetric characteristics of virtual samples is first proposed and verified. Then, using the verified analysis methodology, microstructural characteristics of virtual samples are determined and compared to those of real specimens. To further demonstrate the applicability of the proposed methodology, dynamic modulus simulations of virtually generated samples of asphalt concrete are performed using the finite element software ABAQUS and considering different aggregate characteristics. The results obtained indicate that the proposed methodology can be used as an efficient tool to fabricate and analyse virtual microstructures of asphalt concrete mixtures. This, in turn, becomes an essential step for the improvement of the computational microstructural model under development by the authors, which aims to accurately predict the mechanical behaviour of asphalt mixtures from known constituent properties and geometric characteristics, and to provide significant savings in the time and cost required for laboratory testing of actual specimens.

Enabling consistency in pluripotent stem cell-derived products for research and development and clinical applications through material standards.

There is a need for physical standards (reference materials) to ensure both reproducibility and consistency in the production of somatic cell types from human pluripotent stem cell (hPSC) sources. We have outlined the need for reference materials (RMs) in relation to the unique properties and concerns surrounding hPSC-derived products and suggest in-house approaches to RM generation relevant to basic research, drug screening, and therapeutic applications. hPSCs have an unparalleled potential as a source of somatic cells for drug screening, disease modeling, and therapeutic application. Undefined variation and product variability after differentiation to the lineage or cell type of interest impede efficient translation and can obscure the evaluation of clinical safety and efficacy. Moreover, in the absence of a consistent population, data generated from in vitro studies could be unreliable and irreproducible. Efforts to devise approaches and tools that facilitate improved consistency of hPSC-derived products, both as development tools and therapeutic products, will aid translation. Standards exist in both written and physical form; however, because many unknown factors persist in the field, premature written standards could inhibit rather than promote innovation and translation. We focused on the derivation of physical standard RMs. We outline the need for RMs and assess the approaches to in-house RM generation for hPSC-derived products, a critical tool for the analysis and control of product variation that can be applied by researchers and developers. We then explore potential routes for the generation of RMs, including both cellular and noncellular materials and novel methods that might provide valuable tools to measure and account for variation. Multiparametric techniques to identify "signatures" for therapeutically relevant cell types, such as neurons and cardiomyocytes that can be derived from hPSCs, would be of significant utility, although physical RMs will be required for clinical purposes.

3D casing-distributor analysis with a novel block coupled OpenFOAM solver for hydraulic design application

Nowadays, computational fluid dynamics is commonly used by design engineers to evaluate and compare losses in hydraulic components as it is less expensive and less time consuming than model tests. For that purpose, an automatic tool for casing and distributor analysis will be presented in this paper. An in-house mesh generator and a Reynolds Averaged Navier-Stokes equation solver using the standard k-ω SST turbulence model will be used to perform all computations. Two solvers based on the C++ OpenFOAM library will be used and compared to a commercial solver. The performance of the new fully coupled block solver developed by the University of Lucerne and Andritz will be compared to the standard 1.6ext segregated simpleFoam solver and to a commercial solver. In this study, relative comparisons of different geometries of casing and distributor will be performed. The present study is thus aimed at validating the block solver and the tool chain and providing design engineers with a faster and more reliable analysis tool that can be integrated into their design process.

Development of Single Vial Kits for Preparation of 68Ga-Labelled Peptides for PET Imaging of Neuroendocrine Tumours

The present work was aimed at the formulation and evaluation of freeze-dried kits of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-peptides for the preparation of (68)Ga-labelled peptides for PET imaging of neuroendocrine tumours. The (68)GaCl3 was obtained from the locally produced nanoceria-PAN, composite-sorbent-based (68)Ge/(68)Ga generator. Single vial kits of somatostatin analogues DOTA-[Tyr(3)]-octreotide (DOTA-TOC), DOTA-[NaI(3)]-octreotide (DOTA-NOC) and DOTA-Tyr(3)-Thre(8)-octreotide (DOTA-TATE) were formulated. Optimization of radiolabelling with (68)Ga from the in-house generator, characterization, long term evaluation of stability of kits and bioevaluation studies in animals was carried out. DOTA-TOC, DOTA-NOC and DOTA-TATE kits could be successfully formulated. Consistently high radiochemical yields (>95 %) were obtained on radiolabelling with (68)Ga. The radiolabelled peptides exhibited excellent in vitro stability. Biodistribution studies in normal non-tumour bearing Swiss mice revealed fast clearance of activity via renal route as reported for the respective peptides. Availability of ready to use DOTA-peptide kits in conjunction with (68)Ge/(68)Ga generators would pave way for the establishment of (68)Ga radiopharmacy, a long-felt need of the nuclear medicine community.

Computational Calculation of Gas and Water Properties: Part 2

This is a second part of the series elaborating the programming process for in-house software generation using Visual Basic. The authors explain the state-of-the-art programming process for the estimation and predication of water (brine) properties. Coding has been done in order to estimate the properties with reference to prevailing conditions, showing the effectiveness of developed in-house software. This part of the article also particularly emphasizes on the significance of water formation volume factor, which is usually neglected in oil and gas industry, while highlighting the usefulness and utilization of the generated data (using developed software).

Wideband and non‐dispersive wavelet transmission using leaky lens antenna

An ultra-wideband, non-dispersive leaky lens antenna system for impulse applications has been designed, fabricated and characterised. An in-house wavelet generator is connected to the antenna to transmit 100 ps-long square pulses with centre frequencies at 45, 60 and 75 GHz. It is shown that the leaky lens antenna has negligible distortion and preserves the pulse shape generated by the millimetre-wave pulse generator.

Firms' Investment under Financial and Infrastructure Constraints: Evidence from In-House Generation in Sub-Saharan Africa

Abstract While it is well known that financing and infrastructure constraints negatively affect economic development, the correlations between these constraints have been underexplored in the economics literature. This paper focuses on the implications of financing and infrastructure constraints by studying firms’ investments in electric generators as a response to public power interruptions. A theoretical model demonstrates that financial constraints lower economic returns on owning electric generators, making firms less likely to install private generators if the public power supply becomes unreliable. The empirical results show that, controlling for other factors, firms with a lower cost of external financing are more likely to own private generators in areas where the public power supply is less reliable. Observed correlations among reliability of power supply, financial constraints, and investment in electric generators thus appear consistent with the hypothesis that underdeveloped financial markets and inadequate infrastructure can be a greater barrier for economic development than either of these constraints separately.

Area- and energy-efficient CORDIC accelerators in deep sub-micron CMOS technologies

Abstract. The COordinate Rotate DIgital Computer (CORDIC) algorithm is a well known versatile approach and is widely applied in today's SoCs for especially but not restricted to digital communications. Dedicated CORDIC blocks can be implemented in deep sub-micron CMOS technologies at very low area and energy costs and are attractive to be used as hardware accelerators for Application Specific Instruction Processors (ASIPs). Thereby, overcoming the well known energy vs. flexibility conflict. Optimizing Global Navigation Satellite System (GNSS) receivers to reduce the hardware complexity is an important research topic at present. In such receivers CORDIC accelerators can be used for digital baseband processing (fixed-point) and in Position-Velocity-Time estimation (floating-point). A micro architecture well suited to such applications is presented. This architecture is parameterized according to the wordlengths as well as the number of iterations and can be easily extended for floating point data format. Moreover, area can be traded for throughput by partially or even fully unrolling the iterations, whereby the degree of pipelining is organized with one CORDIC iteration per cycle. From the architectural description, the macro layout can be generated fully automatically using an in-house datapath generator tool. Since the adders and shifters play an important role in optimizing the CORDIC block, they must be carefully optimized for high area and energy efficiency in the underlying technology. So, for this purpose carry-select adders and logarithmic shifters have been chosen. Device dimensioning was automatically optimized with respect to dynamic and static power, area and performance using the in-house tool. The fully sequential CORDIC block for fixed-point digital baseband processing features a wordlength of 16 bits, requires 5232 transistors, which is implemented in a 40-nm CMOS technology and occupies a silicon area of 1560 μm2 only. Maximum clock frequency from circuit simulation of extracted netlist is 768 MHz under typical, and 463 MHz under worst case technology and application corner conditions, respectively. Simulated dynamic power dissipation is 0.24 uW MHz−1 at 0.9 V; static power is 38 uW in slow corner, 65 uW in typical corner and 518 uW in fast corner, respectively. The latter can be reduced by 43% in a 40-nm CMOS technology using 0.5 V reverse-backbias. These features are compared with the results from different design styles as well as with an implementation in 28-nm CMOS technology. It is interesting that in the latter case area scales as expected, but worst case performance and energy do not scale well anymore.

A comprehensive 16 loci-based DNA fingerprinting dataset of a broad tumor cell line panel for cancer research

Motivations. Tumor cell lines are widely used as in vitro models and as screening tools in cancer research. A significant portion of cell lines have been reported to be misidentified, potentially generating misleading data interpretation. Correct assessment of cell line genetic identity is therefore critical to cancer biology studies as well as to drug discovery. Several methods may be applied to authenticate cell lines, but DNA fingerprinting based on the detection of Short Tandem Repeats (STR) has emerged as the standard approach. STR profiles for several commercial cell lines can be retrieved from sparse literature reports or from vendor databases, however these are mainly based on the analysis of 8 loci, except for the NCI60 panel, on which 16 loci were profiled. Inconsistencies can be found in allele designation among the different authors, mainly when more than two alleles per locus are present, as is frequently found in tumor cell lines. A resource to facilitate literature interrogation is represented by the Cell Line Integrated Molecular Authentication database (CLIMA), but to date there are no reported comprehensive databases containing 16 loci profile sets generated in parallel. Here we disclose the in-house generation of a homogeneous 16 loci dataset, reporting the STR profiles for a panel of about 300 tumor cell lines, representative of diverse solid and circulating tumor types. Our intent was to facilitate the management of the internal cell bank, by assessing the identity and stability over time of the tumor cell lines used for research, with the highest accuracy in discrimination and with an optimized score for profile similarity checking. The STR database can be linked to Nerviano Medical Sciences (NMS) internal database, which contains information on cell line origin, morphology, growth conditions, as well as known somatic mutations (from the Wellcome Trust Sanger Institute Cosmic database), thus making it a comprehensive integrated platform for cell line utilization in drug discovery. Our plan is to make the STR database available to the scientific community. Methods. DNA fingerprinting is based on the simultaneous amplification of highly polymorphic STR sites, which are short DNA sequences with a varying number of repeats in each cell line. Genetic abnormalities in tumor cell lines can result in more than two alleles at each locus, which complicates the analysis. Most STR profiles reported so far are based on the analysis of a limited number of STR loci, usually 8. The probability for two individuals to share the same STR profile is estimated to range from ~10-8 for 8 loci to ~10-17 for 16 loci. A 16 loci profile can be beneficial in cancer research, due to the intrinsic genetic instability of tumor cells that may result in allele acquisition or loss. In the current study we performed a 16-loci STR fingerprinting analysis on a panel of about 300 commercially available cancer cell lines. DNA was prepared directly from frozen cells, using NucleoSpin Tissue (Macherey-Nagel), and then analysed using AmpFlSTR Identifiler Plus PCR Amplification kit (Applied Biosystems), that amplifies simultaneously 15 tetranucleotide repeat loci and the amelogenin gender marker. For a more accurate comparison of STR profiles in different cell lines, we have introduced a modification to the standard calculation of similarity scores to account for partial allele identity at each locus, allowing a more precise definition of the level of similarity, which is particularly relevant when multiple alleles are present. This is obtained by applying the following formula that calculates the number of identical alleles at each locus, divided by the total number of alleles: given a cell line A and a cell line B, the score is defined as the identified sum of similarities at each i-th locus s(i) normalized by the number of not empty loci, where s(i) = 2 x [alleles(A) = alleles(B)] / [#alleles(A) + #alleles(B)]. Based on a preliminary sensitivity analysis, the similarity score threshold to classify two cell lines as identical was set at 80%. Results. A DNA fingerprinting analysis based on 16 loci was performed on a panel of about 300 widely used tumor cell lines, purchased at NMS over several years from diverse providers. Using an established cut off of 80%, we found that all cell lines were correctly classified, suggesting that the cell line panel is genetically stable over time. As expected, an overall pairwise analysis of all the different cell line profiles revealed a generally low similarity degree (less than 50%), with no evidence for any similarity bias due to tumor type. The main outcome of this study is the availability of a large 16 loci STR dataset of tumor cell lines, which was integrated as a fundamental part of the NMS Cell Bank database. The STR dataset can be easily interrogated and distributed for use as a reliable reference for cancer research.

Extending the role of computational fluid dynamics in screw machines

Previous publications show that computational fluid dynamics (CFD) can be readily used for the flow prediction and analysis of screw compressors. Several case studies are presented in this article to show the scope and applicability of such methods. These include solid–fluid interaction in screw compressors, prediction of flow generated noise in screw machines, cavitation modelling in gear pumps, and flow in multiphase pumps for oil and gas industry. Numerical grids for all these cases were generated by the authors using an in-house grid generator, while the CFD calculations were performed with a variety of commercially available CFD codes. In order to validate the accuracy of the CFD calculations, an extended test programme was carried out using laser Doppler velocimetry to measure the mean and fluctuating velocity distribution in screw compressor flow domains. The measurement results are then compared with the CFD simulations. The results confirm the viability of the developed techniques. It is shown in this publication that the flexibility of the developed method creates further opportunities for a broader use of CFD for analysis of twin screw machines in a range of new applications.

Design of a standalone-type beryllium vessel for high-pressure protein crystallography

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100+/-1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating copper-anode in-house x-ray generator (0.8 kW). We successfully collected a 2.0 A resolution data set of a 0.5 mm size GI crystal in an aqueous solution at 100 MPa.

Crystallization and preliminary X-ray diffraction studies of the putative haloalkane dehalogenase DppA fromPlesiocystis pacificaSIR-I

DppA from Plesiocystis pacifica SIR-I is a putative haloalkane dehalogenase (EC 3.8.1.5) and probably catalyzes the conversion of halogenated alkanes to the corresponding alcohols. The enzyme was expressed in Escherichia coli BL21 and purified to homogeneity by ammonium sulfate precipitation and reversed-phase and ion-exchange chromatography. The DppA protein was crystallized by the vapour-diffusion method and protein crystals suitable for data collection were obtained in the orthorhombic space group P2(1)2(1)2. The DppA crystal diffracted X-rays to 1.9 A resolution using an in-house X-ray generator.

Rapid determination of 90Sr impurities in freshly “generator eluted” 90Y for radiopharmaceutical preparation

90Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life ( t 1/2=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that 90Y is available conveniently and inexpensively from a radionuclide “generator” by decay of its parent, 90Sr. Nevertheless, current and planned clinical applications with [ 90Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an “in-house” generator or as a fast QC method for analysis of 90Y solutions. In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO 3 eluate: in this fraction the concentration of 90Sr must be smaller than 10 −5% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of 90Y in all the fractions containing “only” radio-Sr: 90Y should not be present in these eluates. After the collection of β − and γ spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.

ヨードチロシンの部位特異的導入と長波長Ｘ線を用いた単波長異常分散法による結晶構造解析

Iodine is a good anomalous scatter for radiations from in-house X-ray generators (Cu/CrKα). Non-natural amino acid, 3-iodo-L-tyrosine, is able to be site-specifically incorporated into proteins with amber suppresser tRNA and mutated TyrRS from M. jannaschii in the E. coli expression system. To determine the crystal structure of acetyl transferase from T. thermophilus, iodotyrosine-containing proteins were prepared and crystallized. Structure determination was successfully conducted with the protein variant with iodotyrosine at position 111. Anomalous signals from iodotyrosine with Cu/CrKα radiations were both sufficient to calculate clear electron density map. In the crystal structure, iodotyrosine did not significantly disturb the native structure.

A shot in the dark

Investigations of recent blackouts indicate that the root cause of almost all of these major power system disturbances is voltage collapse rather than the underfrequency conditions prevalent in the blackouts of the 1960s and 1970s. The operation of today's power system with generation frequently being remote from the load centers has made the power system very dependent on the utility transmission system. When transmission lines trip, voltage drops at the load center, whereas frequency may remain normal until a complete system collapse occurs. Utilities have begun to recognize this problem and are installing UVLS programs. Also the industrial customers that have in-house generation that operates in parallel with the utility need to recognize the problem. These industrial cogeneration customers should consider the use of undervoltage separation schemes in addition to their existing underfrequency schemes to address the voltage collapse scenario. This article proposes undervoltage separation logic schemes that can be easily installed within digital relays to enhance the security of an undervoltage separation to prevent false operation due to slow-clearing system faults. The article also indicates the required point of installation of these relays so that they properly measure system voltage.

Nuclear imaging of neuroendocrine tumours

The diagnosis of neuroendocrine tumours (NETs) and monitoring of therapy in many patients relies mainly on morphological imaging techniques such as computed tomography (CT), ultrasound (US) and magnetic resonance imaging (MRI). However, functional imaging modalities--such as somatostatin receptor scintigraphy (SRS)--have great impact on patient management by providing tools for better staging of the disease, visualization of occult tumour, and evaluation of eligibility for somatostatin analogue treatment. Positron emission tomography (PET) using (18)F-fluoro-deoxy-glucose (FDG) is a powerful functional modality for oncological imaging. Unfortunately, FDG is not accumulated in NETs except in the case of dedifferentiated tumours and tumours with high proliferative activity. Based on the concept of amine precursor uptake and decarboxylation (APUD), the (18)F- and (11)C-labelled amine precursors L-dihydroxyphenylalanine and 5-hydroxy-L-tryptophan (5-HTP) have been utilized for PET imaging of NETs. In comparative studies of patients with a variety of NETs, (11)C5-HTP-PET proved better than CT and SRS by visualizing additional small lesions. With carbidopa premedication orally before (11)C5-HTP-PET examination the tumour uptake could be increased and the urinary radioactivity concentration considerably reduced. This concept may also be applied to (18)F-L-DOPA-PET, a method which in a limited number of studies has gained additional diagnostic information in NET patients compared to SRS and morphological imaging. (68)Ga is available from an in-house generator and has been utilized for labelling of somatostatin analogues for PET imaging of NETs with promising results in a small number of patients. However, SRS is an established functional imaging method for patients with NETs, whereas the role for PET in the clinical routine needs further evaluation in comparative studies in larger groups of patients.

Crystallization and preliminary X-ray diffraction analysis ofLeishmania majordihydroorotate dehydrogenase

Dihydroorotate dehydrogenases (DHODHs) are flavin-containing enzymes that catalyze the oxidation of L-dihydroorotate to orotate, the fourth step in the de novo pyrimidine nucleotide synthesis pathway. In this study, DHODH from Leishmania major has been crystallized by the vapour-diffusion technique using lithium sulfate as the precipitating agent. The crystals belong to space group P6(1), with unit-cell parameters a = 143.7, c = 69.8 A. X-ray diffraction data were collected to 2.0 A resolution using an in-house rotating-anode generator. Analysis of the solvent content and the self-rotation function indicate the presence of two molecules in the asymmetric unit. The structure has been solved by the molecular-replacement technique.

Expression, purification, crystallization and preliminary X-ray analysis of the olfactomedin domain from the sea urchin cell-adhesion protein amassin.

A family of animal proteins is emerging which contain a conserved protein motif known as an olfactomedin (OLF) domain. Novel extracellular protein-protein interactions occur through this domain. The OLF-family member amassin, from the sea urchin Strongylocentrotus purpuratus, has previously been identified to mediate a rapid cell-adhesion event resulting in a large aggregation of coelomocytes, the circulating immune cells. In this work, heterologous expression and purification of the OLF domain from amassin was carried out and initial crystallization trials were performed. A native data set has been collected, extending to 2.7 A under preliminary cryoconditions, using an in-house generator. This work leads the way to the determination of the first structure of an OLF domain.

Crystallization and preliminary X-ray analysis of a novel Kunitz-type kallikrein inhibitor from Bauhinia bauhinioides.

A Kunitz-type protease inhibitor (BbKI) found in Bauhinia bauhinioides seeds has been overexpressed in Escherichia coli and crystallized at 293 K using PEG 4000 as the precipitant. X-ray diffraction data have been collected to 1.87 A resolution using an in-house X-ray generator. The crystals of the recombinant protein (rBbKI) belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 46.70, b = 64.14, c = 59.24 A. Calculation of the Matthews coefficient suggests the presence of one monomer of rBbKI in the asymmetric unit, with a corresponding solvent content of 51% (VM = 2.5 A3 Da(-1)). Iodinated crystals were prepared and a derivative data set was also collected at 2.1 A resolution. Crystals soaked for a few seconds in a cryogenic solution containing 0.5 M NaI were found to be reasonably isomorphous to the native crystals. Furthermore, the presence of iodide anions could be confirmed in the NaI-derivatized crystal. Data sets from native and derivative crystals are being evaluated for use in crystal structure determination by means of the SIRAS (single isomorphous replacement with anomalous scattering) method.

Crystallization and preliminary X-ray analysis of the YjgF/YER057c/UK114-family protein ST0811 fromSulfolobus tokodaiistrain 7

ST0811 from Sulfolobus tokodaii strain 7, a member of the YjgF/YER057c/UK114 protein family, was crystallized by the sitting-drop vapour-diffusion method using PEG 10,000 as precipitant. The crystals diffracted X-rays to beyond 2.0 A resolution using an in-house rotating-anode generator. The crystals belonged to the rhombohedral space group R3, with hexagonal unit-cell parameters a = b = 55.0, c = 223.2 A. The crystals contained two molecules in the asymmetric unit (VM = 2.3 A3 Da(-1)) and had a solvent content of 47%.