bluuebunny/crossref_metadata_2025 huggingface dataset:
Moving towards pathogen‐specific T cells post‐stem cell transplant as standard of care
Authors: Blyth E. , Clancy L. , Gottlieb D.
Published: April 2015

Infection remains a large contributor to mortality post‐allogeneic haemopoietic stem cell transplantation (HSCT). Non‐bacterial pathogens cause disease post‐HSCT due to impaired cellular immunity that persists for months to years. Treatment with antiviral or antifungal pharmacotherapy is problematic due to drug toxicity, treatment failure and high cost. Pathogen‐specific T cells (PSTs) from transplant donors provide a potential solution to the problem of impaired recipient immunity by directly and rapidly reconstituting immunity, thereby preventing or controlling infections. A number of phases I and II clinical trials of PSTs that have focused primarily on cytomegalovirus, Epstein–Barr virus and adenovirus have now been performed in the prophylactic, pre‐emptive and treatment settings. These trials show that transferred cells are safe and that they expand in vivo, respond to viral antigens and can prevent or control disease. At the current time, manufacture remains the domain of large centres with the necessary expertise and infrastructure, but automation and standardization will allow techniques to be more widely adopted. It is clear that adoptive T cell transfer will form part of the future of transplantation, with the current challenge being to perform large randomized clinical trials demonstrating safety and efficacy to justify the investment in infrastructure required for widespread incorporation of this therapy into routine clinical practice.
Non‐invasive prenatal testing of monogenic fetal characteristics by maternal plasmaDNAanalysis
Authors: Han D. S. C. , Lo Y. M. D.
Published: April 2015

Since its discovery in 1997, cell‐free fetalDNAin maternal plasma has offered exciting avenues for non‐invasive prenatal testing of many fetal disorders, including monogenic diseases. Fetal sexing for sex‐linked diseases and congenital adrenal hyperplasia andRhesusDgenotyping are now clinically performed in many centres. Paternally inherited traits can be detected in maternal plasma to diagnose paternally inherited autosomal dominant disorders, while the absence of paternally inherited mutations can exclude autosomal recessive disorders. The precise quantification offered by single‐molecule counting technologies has facilitated the accurate measurement of genotype and haplotype imbalances in maternal plasma. Such measurements are useful for deducing the inheritance status of the foetus using approaches called relative mutation dosage analysis and relative haplotype dosage analysis. It has also been demonstrated that the entire fetal genome could be sequenced from maternal plasma. Feasibility studies have been performed for detection of fetalde novomutations from maternal plasma. It is likely that the application of non‐invasive prenatal testing of maternal plasma for fetal monogenic diseases would increase in the near future.
Receptor–ligand interactions underlying RBC invasion in Babesia
Authors: Lobo C. A. , Cursino‐Santos J. R. , Rodriguez M. , Ord R. , Singh M.
Published: April 2015

Babesiosis is a zoonosis, a disease communicable from animals to man. The rodent parasite, Babesia microti and the bovine pathogen, Babesia divergens are responsible for most of the human infections that have been reported to date, globally. From a blood safety perspective, transfusion‐transmitted infections involving Babesia spp. have become increasingly problematic in the USA. Therefore, the study of this blood‐borne parasite should be considered as a priority for transfusion medicine. Our purpose is to understand the invasion process of B. divergens into the human RBC, with the ultimate aim of exploiting parasite molecules found to play key roles in invasion as diagnostic and blood screening tools. The in‐vitro system that we use for studying invasion of the human red cell by B. divergens permits direct exploration of the events associated with parasite invasion of the human RBC, using viable merozoites of B. divergens. Molecules on the surface of the parasite and those secreted by apical organelles function at the host/parasite interface, and we need to identify them and determine their interactions and function, if we are to define the steps in the invasion mechanism and identify new therapeutic targets. We have identified multiple parasite molecules that bind the human RBC, and we will present results on their identification, characterization and potential RBC receptors. We anticipate the study of molecular mechanisms involved in the entry of Babesia merozoites into the RBC will result in reagents for diagnosis, epidemiology and treatment and prevention of human babesiosis and assist in developing products to screen blood products.
Serological tools for investigating immunohaematology problems
Authors: Thornton N.
Published: April 2015

Antibody identification is fundamental to the practice of immunohaematology. Although the molecular era is undoubtedly upon us, serological techniques remain the essential tools required for problem‐solving in the transfusion laboratory. Direct agglutination tests, the indirect antiglobulin test (IAT) and the use of cells treated with proteases such as papain or ficin make up the standard battery of tests employed in the routine immunohaematology laboratory, and in most cases, these tests alone are sufficient to give the information needed to guide clinical decisions regarding suitable blood for transfusion. When the use of standard serological techniques are insufficient to resolve problem, we must turn to the additional serological tools at our disposal, which include: testing over a wide thermal range, adsorption and elution techniques, the use of cells treated with a range of enzymes and chemicals, inhibitory substances, using rare cells and serum and the MAIEA assay. Whilst these supplementary serological tools are undeniably very useful, knowledge of blood groups, antibody characteristics and fundamental basic serological methods is essential for choosing the appropriate tests in a stepwise and efficient manner. The overall goal is to minimise delay in patient care, therefore a systematic approach is required when investigating immunohaematology problems to ensure the necessary tools are used effectively, to achieve a timely resolution.
Molecular mechanisms regulating platelet clearance and thrombopoietin production
Authors: Grozovsky R. , Giannini S. , Falet H. , Hoffmeister K.M.
Published: April 2015

The human body produces and removes 1011 platelets daily to maintain a normal steady‐state platelet count. Platelet production must be tightly regulated to avoid spontaneous bleeding if counts are low (thrombocytopenia) or arterial occlusion and organ damage if counts are high (thrombocytosis). Recent studies have highlighted the role of glycan modifications on platelet surface proteins in mediating platelet clearance. Platelets undergoing cold storage lose sialic acid and β‐galactose. Following transfusion, cold‐stored platelets are cleared via hepatic Ashwell–Morell receptor (AMR) and the macrophage (Kupffer cell) αMβ2 integrin lectin domain. New data point to the fact that platelets surface loses sialic acid during their circulatory lifetime, suggesting a novel platelet in vivo clearance mechanism via the AMR. Thrombopoietin (TPO) is the primary regulator of platelet production, supporting the survival, proliferation and differentiation of the platelet precursors, bone marrow megakaryocytes. Although it is clear that hepatocytes are the primary source of TPO, the mechanisms regulating circulating TPO levels have been subject to discussion for decades. Two major models for TPO regulation have been proposed. In one model, hepatic TPO production is constitutive and TPO serum levels are maintained solely by its uptake and metabolism by the TPO receptor c‐Mpl on platelets and megakaryocytes. In another model, hepatic TPO production is regulated. However, the physiological ligand–receptor pair capable of regulating steady‐state TPO production remains unclear. In this review, mechanisms of glycan–lectin‐mediated platelet clearance and TPO production will be discussed.
Oxidative damage and iron effects following RBC transfusion
Authors: Spitalnik S. L. , Francis R. O.
Published: April 2015

It is controversial whether transfusion of red blood cells (RBCs) after prolonged refrigerated storage induces adverse effects. Nonetheless, due to the RBC ‘storage lesion’, at outdate, the 24‐h post‐transfusion RBC recovery averages 75% in healthy recipients; alternatively, ~25% of these RBCs are cleared, mostly within 1–2 h post‐transfusion. Clearance is even greater in hospitalized patients. In addition, oxidative damage is, at least partly, responsible for the storage lesion. We hypothesized that donors with RBCs that are less, or more, able to withstand oxidative stress could constitute ‘poor storers’, or ‘super storers’, respectively. We also hypothesized that delivering a bolus of haemoglobin‐derived iron, resulting from macrophage catabolism of these rapidly cleared RBCs, is responsible for, at least some of, the adverse effects of these transfusions. For example, increased intracellular iron levels enhance the virulence of intracellular bacterial pathogens. Furthermore, in this setting, excess iron is exported to plasma through ferroportin at a pace exceeding transferrin's rate of iron uptake, thereby producing circulating non‐transferrin‐bound iron, which enhances the virulence of extracellular pathogens. To address the ‘iron hypothesis’, we are using cell culture models in vitro, murine and canine models in vivo, and transfusion studies in healthy human volunteers. Although experimental results demonstrate the effects of the post‐transfusion release of iron on infection, several unresolved questions remain.
Protecting the health and safety of cell and tissue donors
Authors: Stroncek D. F. , England L.
Published: April 2015

Centres involved with collecting the starting material for cell and tissue therapies are obligated to protect the recipient's and donor's health and safety. All donors face risks during and after the collection which can be minimized by pre‐screening donors and excluding those that the collection would place at increased risk of physical harm. Another important part of protecting donors is the use of appropriate collection facilities. Donor risk can also be reduced using specially designed collection devices and ancillary equipment, using only trained collection staff and limiting the volume or quantity of biological material collected. Donors should be monitored during and after the collection for adverse events and should adverse events occur; they should be promptly and appropriately treated. Protecting the safety of cell, gene and tissue donors is particularly difficult because of the wide variety in the types of donors and material collected. Biological material used to manufacture cell and tissue therapies is collected from healthy volunteers, matched related, matched unrelated and autologous donors. Precautions should be taken to ensure that the team of medical professionals evaluating related donors is not the same as the team caring for the transplant recipient to be sure that the donor evaluation is not biased and the donor is not coerced into donating. In conclusion, protecting cell and tissue donors requires the use of the practices developed to protect blood donors and the implementation of many other measures.
ABO subgroup studies in Korea
Authors: Cho D. , Lee S. Y. , Ryang D. W.
Published: April 2015

Numerous examples of A or B subgroup alleles have been described in many geographical and ethnic groups. To analyse the phenotypic and genotypic basis of some ABO subgroups in Korea, a large‐scale study was performed on 169 605 samples from Korean blood donors. The overall incidence of ABO subgroups was 0·13% (227/169,605) in this donor population. Based on genotyping and/or serologic typing, the subgroups identified were as follows: A2B (n = 120), A2B3 (n = 36), A1B3 (n = 22), A2 (n = 13), B3 (n = 13), AintB3 (n = 6) and others (n = 17). Amongst these individuals with ABO subgroups, 26·4% (60/227) demonstrated a cis‐AB01 allele. It has been reported that the Korean population has several unique ABO subgroups (Aw10, Aw14 and B306) showing allelic competition or allelic enhancement. Several congenital blood chimaeras have been also found when studying individuals with ABO subgroups. Like ABO subgroups showing the allelic enhancement and allelic competition, chimaerism is also an important cause of ABO phenotype–genotype discrepancies when implementing DNA‐based blood grouping techniques. To understand the pattern of A and B antigen expression amongst donors with subtype alleles, flow cytometric analysis of ABO antigen expression on HeLa cells transfected with plasmids containing various mutants was used, in addition to ABO genotyping.
Advances in testing technology to ensure transfusion safety – NAT and beyond
Authors: Stramer S. L. , Dodd R. Y. , Chiu C. Y.
Published: April 2015

Aims

To provide an update on state‐of‐the‐art testing technologies for infectious disease (ID) blood donation screening, including emerging molecular methods such as multiplexed nucleic acid testing (NAT) platforms, mass spectrometry, nucleic acid and protein microarrays, and next‐generation sequencing.

Background

Testing donated blood for ID markers plays a major role in establishing and maintaining blood safety. The norm for ID testing has been serology, but increasingly, NAT is used where resources allow, including testing for emerging infectious disease (EID) agents. The appropriate mix of ID tests and associated algorithms depends on local epidemiology, infrastructure and economic considerations. Although NAT will detect acute infections, not all pathogens have adequate concentrations of nucleic acid for detection in the early acute or later chronic phases of infection. Thus, both NAT and serological approaches may be required to detect recent, current or past infection. The advent of new technologies to augment or potentially replace current NAT and/or serologic testing has spurred debate as to their optimal future role in blood‐borne pathogen screening.

Methods and Results

Infectious disease testing has progressed from manual technologies using single markers to highly multiplexed automated assays. Emerging technologies allow the simultaneous detection and differentiation of hundreds of pathogens and will likely play an important role in future testing, but there are many hurdles prior to routine adoption.

Conclusions

Blood systems worldwide must be ready to adapt to EID agents, availability of new diagnostic technologies, and shifts in economic conditions and public expectations to accommodate the changing landscape of ID testing.
RBC substitutes: from the past to the future
Authors: Choe W. H. , Baek E. J.
Published: April 2015

The world is faced with an ever decreasing supply of blood products. Thus, studies on developing alternative blood substitutes have been continuously performed. During the 1960s, intravenous solutions and various artificial blood products were used during wartimes. For example, perfluorocarbon‐ and haemoglobin‐based oxygen carriers were developed as cell‐free oxygen carriers that could replace the function of red blood cells (RBCs). However, most of these carriers showed unsatisfactory results. In recent years, RBCs generated from stem cells appeared promising. Using haematopoietic stem cells, embryonic stem cells and induced pluripotent stem cells, enucleated RBCs with comparable function to donor RBCs could be harvested. However, many hurdles need to be overcome before RBC substitutes can be produced on a massive scale.
Cost‐effectiveness of patient blood management methods in elective orthopaedic surgery
Authors: So – Osman C.
Published: April 2015

Background

A randomized study was conducted on the integrated use of patient blood management methods as erythropoietin (Epo), cell saver and/or postoperative drain reinfusion to evaluate the effect on red blood cell (RBC) transfusion reduction and costs in 2442 adult elective hip and knee surgery patients while applying a restrictive transfusion threshold.

Methods

Firstly, patients were stratified by the preoperative haemoglobin (Hb) level: low Hb (10–13 g/dl) patients were randomized for Epo or no Epo and normal Hb patients (above 13 g/dl) were ineligible for Epo. Secondly, patients from both strata were randomized for autologous reinfusion by cell saver device or postoperative drain reinfusion device or for no blood salvage device. Outcome measures: RBC use and cost‐effectiveness.

Results

Epo resulted in a significant 50% reduction of transfused patients (OR 0·5, 95% CI: 0·35–0·75) and a non‐significant 29% mean reduction in RBC use (ratio 0·71, 0·42–1·13). Epo, however, increased costs by €785 per patient (262–1309), that is €7300 per avoided transfusion (1900–24000). In both strata, autologous blood reinfusion did not result in a RBC reduction and increased costs by €378 per patient (161–595).

Conclusions

In elective knee and hip surgery, while using a restrictive transfusion trigger, autologous reinfusion by cell saver and postoperative drain reinfusion were no longer found to be effective in reducing RBC use and are consequently not cost‐effective, while Epo, although it is effective in reducing RBC use, is not cost‐effective due to its high costs. Therefore, these interventions are no longer considered as appropriate transfusion alternatives.
Blood donation by African migrants and refugees in Australia
Authors: McQuilten Z. K. , Polonsky M. J. , Renzaho A. M. N.
Published: April 2015

Changing population demographics have important implications for the ability of transfusion services to meet the transfusion requirements of minority groups. In Western countries, differences in red‐blood‐cell (RBC) antigens between predominantly Caucasian blood donors and recipients from different demographic backgrounds may result in higher RBC alloimmunization rates, particularly in those who are chronically transfused, and can make it more difficult to source compatible blood. Ensuring blood donors are representative of the general population is particularly relevant for patients of African descent, who have a number of important blood group differences from Caucasians. However, there are challenges in ensuring a representative donor population, especially when the national population is very multicultural. Research in African migrants and refugees living in Australia has identified blood donation knowledge, misconceptions about blood donation from experiences prior to migration, and perceptions or experiences of discrimination within the host country as important determinants of blood donation. Therefore, promotion of knowledge and awareness of blood donation and blood and health service processes should be considered to assist with the recruitment of migrant donors.
Blood donation screening for Babesia microti: feasibility and results
Authors: Moritz Erin D. , Stramer Susan L.
Published: April 2015

Background and Objectives

Babesia microti, an intraerythrocytic parasite, causes babesiosis; transfusion‐transmitted babesiosis (TTB) is reported primarily in the United States where no licensed screening tests are available.

Materials and Methods

Babesia microti donor screening results using investigational antibody and DNA tests in six US states are reviewed from both repository testing and prospective screening. Testing results performed in endemic counties from June 2012 to April 2014 were combined to update prevalence and marker duration in infected donors and estimate testing efficacy (i.e. the reduction of reported TTB cases).

Results

A total of 84 209 donations were tested and 331 were reactive by either antibody and/or DNA for a total prevalence of 0·39%. Of those that were DNA positive, the retrieved red cell units from nearly one‐third caused infection in hamsters. In addition, eight units were identified that were PCR positive but antibody negative (window‐period donors).

Conclusions

Screening is feasible, removing likely infectious donations. Followed donors retained PCR positivity over several months but antibody reactivity for over 3 years.
EFFECTS OF FLUID AND COMPUTED TOMOGRAPHIC TECHNICAL FACTORS ON CONSPICUITY OF CANINE AND FELINE NASAL TURBINATES
Authors: Uosyte Raimonda , Shaw Darren J. , Gunn‐Moore Danielle A. , Fraga‐Manteiga Eduardo , Schwarz Tobias
Published: April 2015

Turbinate destruction is an important diagnostic criterion in canine and feline nasal computed tomography (CT). However decreased turbinate visibility may also be caused by technical CT settings and nasal fluid. The purpose of this experimental, crossover study was to determine whether fluid reduces conspicuity of canine and feline nasal turbinates in CT and if so, whether CT settings can maximize conspicuity. Three canine and three feline cadaver heads were used. Nasal slabs were CT‐scanned before and after submerging them in a water bath; using sequential, helical, and ultrahigh resolution modes; with images in low, medium, and high frequency image reconstruction kernels; and with application of additional posterior fossa optimization and high contrast enhancing filters. Visible turbinate length was measured by a single observer using manual tracing. Nasal density heterogeneity was measured using the standard deviation (SD) of mean nasal density from a region of interest in each nasal cavity. Linear mixed‐effect models using the R package ‘nlme’, multivariable models and standard post hoc Tukey pair‐wise comparisons were performed to investigate the effect of several variables (nasal content, scanning mode, image reconstruction kernel, application of post reconstruction filters) on measured visible total turbinate length and SD of mean nasal density. All canine and feline water‐filled nasal slabs showed significantly decreased visibility of nasal turbinates (P < 0.001). High frequency kernels provided the best turbinate visibility and highest SD of aerated nasal slabs, whereas medium frequency kernels were optimal for water‐filled nasal slabs. Scanning mode and filter application had no effect on turbinate visibility.
USE OF CONTRAST‐ENHANCED COMPUTED TOMOGRAPHY TO STUDY THE CRANIAL MIGRATION OF A LUMBOSACRAL INJECTATE IN CADAVER DOGS
Authors: Kawalilak Lukas T. , Tucker Russell L. , Greene Stephen A.
Published: April 2015

Volumes used in lumbosacral epidural injections for anesthesia have remained unchanged since the 1960s. The goals of this cross‐sectional observational study were to characterize the three‐dimensional spread of a lumbosacral epidural injection, as well as confirm that the commonly used volume of 0.2 ml/kg injected into the lumbosacral epidural space reaches the thoracolumbar (TL) junction in the majority (≥80%) of dogs. Ten clinically normal, adult, nonpregnant, mixed‐breed dogs were obtained within five minutes of euthanasia and 0.2 ml/kg of radiopaque contrast medium was injected into the lumbosacral epidural space. A computed tomography scan of the TL spine was performed immediately following the injection. Migration of contrast reached the TL junction in 8 of 10 (80%) dogs. Contrast was well visualized in all epidural planes with contrast travelling predominantly in the dorsal epidural space in 7 of 10 (70%) dogs. There was no significant difference in the weight of dogs where the epidural injectate reached the TL junction and those where it did not (P= 0.16), or in the weight of dogs where the cranial‐most point of the contrast column was in the dorsal versus the ventral epidural space (P= 0.32). This preliminary study supports the use of computed tomography to characterize injectate distribution in the canine thoracolumbar epidural space and provides evidence that a 0.2‐ml/kg volume is likely to reache the TL junction in most dogs. Further studies are needed in live dogs to determine if variables affecting human epidural injectate doses have similar effects in the dog.
Preoperative β‐cell function in patients with type 2 diabetes is important for the outcome of Roux‐en‐Y gastric bypass surgery
Authors: Lund Michael Taulo , Hansen Merethe , Skaaby Stinna , Dalby Sina , Støckel Mikael , Floyd Andrea Karen , Bech Karsten , Helge Jørn Wulff , Holst Jens Juul , Dela Flemming
Published: April 2015

Key points

Roux‐en‐Y gastric bypass surgery leads to remission of type 2 diabetes in the majority of patients suffering from the disease.

The gut hormone glucagon‐like peptide‐1 is believed to be of major importance for the remission process.

The present project demonstrates a marked difference in the chance of remission of type 2 diabetes in patients with low or high preoperative β‐cell function in spite of a similar post‐surgery increase in postprandial glucagon‐like peptide‐1 release.

Furthermore, post‐surgery intravenous glucose administration, which does not stimulate release of glucagon‐like peptide‐1, leads to increased insulin secretion in the patients with the best preoperative β‐cell function.

Together the present findings indicate that patients with type 2 diabetes with high preoperative β‐cell function experience a glucagon‐like peptide‐1‐independent increase in β‐cell function after gastric bypass surgery.

The majority of the patients with type 2 diabetes (T2DM) show remission after Roux‐en‐Y gastric bypass (RYGB). This is the result of increased postoperative insulin sensitivity and β‐cell secretion. The aim of the present study was to elucidate the importance of the preoperative β‐cell function in T2DM for the chance of remission after RYGB. Fifteen patients with and 18 without T2DM had 25 g oral (OGTT) and intravenous (IVGTT) glucose tolerance tests performed at inclusion, after a diet‐induced weight loss, and 4 and 18 months after RYGB. Postoperative first phase insulin secretion rate (ISR) during the IVGTT and β‐cell glucose sensitivity during the OGTT increased in T2DM. Postoperative insulin sensitivity and the disposition index (DI) markedly increased in both groups. By stratifying the T2DM into two groups according to highest (T2DMhigh) and lowest (T2DMlow) baseline DI, a restoration of first phase ISR and β‐cell glucose sensitivity were seen only in T2DMhigh. Remission of type 2 diabetes was 71 and 38% in T2DMhigh and T2DMlow, respectively. Postoperative postprandial GLP‐1 concentrations increased markedly, but did not differ between the groups. Our findings emphasize the importance of the preoperative of β‐cell function for remission of diabetes after RYGB.
The effects of resistance exercise training on macro‐ and micro‐circulatory responses to feeding and skeletal muscle protein anabolism in older men
Authors: Phillips Bethan E. , Atherton Philip J. , Varadhan Krishna , Limb Marie C. , Wilkinson Daniel J. , Sjøberg Kim A. , Smith Kenneth , Williams John P.
Published: April 2015

Key points

Increases in limb blood flow in response to nutrition are reduced in older age.

Muscle microvascular blood flow (MBF) in response to nutrition is also reduced with advancing age and this may contribute to age‐related ‘anabolic resistance’.

Resistance exercise training (RET) can rejuvenate limb blood flow responses to nutrition in older individuals.

We report here that 20 weeks of RET also restores muscle MBF in older individuals.

Restoration of MBF does not, however, enhance muscle anabolic responses to nutrition.

The anabolic effects of dietary protein on skeletal muscle depend on adequate skeletal muscle perfusion, which is impaired in older people. This study explores fed state muscle microvascular blood flow, protein metabolism and exercise training status in older men. We measured leg blood flow (LBF), muscle microvascular blood volume (MBV) and muscle protein turnover under post‐absorptive and fed state (i.v. Glamin to double amino acids, dextrose to sustain glucose ∼7–7.5 mmol l−1) conditions in two groups: 10 untrained men (72.3 ± 1.4 years; body mass index (BMI) 26.5 ± 1.15 kg m2) and 10 men who had undertaken 20 weeks of fully supervised, whole‐body resistance exercise training (RET) (72.8 ± 1.4 years; BMI 26.3 ± 1.2 kg m2). We measured LBF by Doppler ultrasound and muscle MBV by contrast‐enhanced ultrasound. Muscle protein synthesis (MPS) was measured using [1, 2‐13C2] leucine with breakdown (MPB) and net protein balance (NPB) by ring‐[D5] phenylalanine tracers. Plasma insulin was measured via ELISA and indices of anabolic signalling (e.g. Akt/mTORC1) by immunoblotting from muscle biopsies. Whereas older untrained men did not exhibit fed‐state increases in LBF or MBV, the RET group exhibited increases in both LBF and MBV. Despite our hypothesis that enhanced fed‐state circulatory responses would improve anabolic responses to nutrition, fed‐state increases in MPS (∼50–75%; P < 0.001) were identical in both groups. Finally, whereas only the RET group exhibited fed‐state suppression of MPB (∼–38%; P < 0.05), positive NPB achieved was similar in both groups. We conclude that RET enhances fed‐state LBF and MBV and restores nutrient‐dependent attenuation of MPB without robustly enhancing MPS or NPB.
Strengthening and Improving Yield Asymmetry of Magnesium Alloys by Second Phase Particle Refinement Under the Guidance of Integrated Computational Materials Engineering
Authors: Li Dongsheng , Lavender Curt
Published: April 2015

Improving yield strength and asymmetry is critical to expand applications of magnesium alloys in industry for higher fuel efficiency and lower CO2 production. Grain refinement is an efficient method for strengthening low symmetry magnesium alloys, achievable by precipitate refinement. This study provides guidance on how precipitate engineering will improve mechanical properties through grain refinement. Precipitate refinement for improving yield strengths and asymmetry is simulated quantitatively by coupling a stochastic second phase grain refinement model and a modified polycrystalline crystal viscoplasticity φ-model. Using the stochastic second phase grain refinement model, grain size is quantitatively determined from the precipitate size and volume fraction. Yield strengths, yield asymmetry, and deformation behavior are calculated from the modified φ-model. If the precipitate shape and size remain constant, grain size decreases with increasing precipitate volume fraction. If the precipitate volume fraction is kept constant, grain size decreases with decreasing precipitate size during precipitate refinement. Yield strengths increase and asymmetry approves to one with decreasing grain size, contributed by increasing precipitate volume fraction or decreasing precipitate size.
Optimal Force Inputs for Environmental Vibration Testing of Full Scale Slender Aerospace Vehicles
Authors: Ramkrishna D. , Joshi Ashok , Mujumdar P. M. , Krishna Y.
Published: April 2015

A hypothesis is presented in this paper for evaluating the root mean square (RMS) errors in acceleration for determining the optimal locations of the exciters during the vibration testing of slender flexible structures, e.g., missiles, rockets, and space vehicles. Simulation studies are carried out on a realistic slender nonuniform beam in a free–free conditions to characterize the error estimations in the desired and achieved acceleration spectra at different locations of the structure. The optimal locations of the exciters are obtained using a real-coded genetic algorithm (RCGA) with minimal required force levels and the corresponding RMS error estimates. It has been observed that RMS force levels are a minimum when the exciter and control sensor locations are noncollocated. This study also provides a methodology in deriving the optimum force levels required for the environmental vibration testing of the full vehicle structure. The RMS error levels are found to be a minimum at the control sensor locations.
Study on Piston Slap Induced Liner Cavitation
Authors: Wang Xiaoyu , Ohta Kazuhide
Published: April 2015

Liner cavitation induced by piston slap in a diesel engine is caused by water pressure fluctuation when the pressure of coolant falls below saturated vapor pressure. Cavitation erosion of cylinder liners is thought to be generated by the impulsive pressure or jet flow impingement following the collapse of cavitation bubbles. In this study, a numerical method to predict the water pressure fluctuation in water coolant passage induced by piston slap impact force is developed. In complimentary impact vibration experiments, high frequency components of the water pressure fluctuation can be seen just after the pressure reaches the saturated vapor pressure level or less. These high frequency components seem to show the occurrence of cavitation. A finite element acoustic model of the water coolant passage in an actual engine block is created and its validity is confirmed by the acoustic vibration tests in air. Then, the coupled vibration characteristics of the water acoustic field and engine block structure are determined, and water pressure waveform induced by piston slap is predicted.
Mechanical Response of Hollow Metallic Nanolattices: Combining Structural and Material Size Effects
Authors: Montemayor L. C. , Greer J. R.
Published: April 2015

Ordered cellular solids have higher compressive yield strength and stiffness compared to stochastic foams. The mechanical properties of cellular solids depend on their relative density and follow structural scaling laws. These scaling laws assume the mechanical properties of the constituent materials, like modulus and yield strength, to be constant and dictate that equivalent-density cellular solids made from the same material should have identical mechanical properties. We present the fabrication and mechanical properties of three-dimensional hollow gold nanolattices whose compressive responses demonstrate that strength and stiffness vary as a function of geometry and tube wall thickness. All nanolattices had octahedron geometry, a constant relative density, ρ ∼ 5%, a unit cell size of 5–20 μm, and a constant grain size in the Au film of 25–50 nm. Structural effects were explored by increasing the unit cell angle from 30 deg to 60 deg while keeping all other parameters constant; material size effects were probed by varying the tube wall thickness, t, from 200 nm to 635 nm, at a constant relative density and grain size. In situ uniaxial compression experiments revealed an order of magnitude increase in yield stress and modulus in nanolattices with greater lattice angles, and a 150% increase in the yield strength without a concomitant change in modulus in thicker-walled nanolattices for fixed lattice angles. These results imply that independent control of structural and material size effects enables tunability of mechanical properties of three-dimensional architected metamaterials and highlight the importance of material, geometric, and microstructural effects in small-scale mechanics.
Analytical Modeling of Trapeze and Poynting Effects of Initially Twisted Beams
Authors: Jiang Fang , Yu Wenbin , Hodges Dewey H.
Published: April 2015

An asymptotically correct, nonlinear, analytical cross-sectional analysis is developed for pretwisted, isotropic beams under axial load and torsion. A comprehensive model is presented that for the first time simultaneously counts for both trapeze and Poynting effects (either positive or negative). Several material models are used and differences are discussed in detail. The limitations of the uniaxial stress assumption and Saint-Venant/Kirchhoff materials are illustrated. Compared to the widely accepted results in the literature, the present theory demonstrates improved results without introducing assumptions commonly used in other works. It is concluded that the trapeze and Poynting phenomena are governed by the material models and warping functions, and nonlinearly coupled extension and torsion can be eliminated by properly selecting the thickness-to-width ratio.
What Portion of the Soft Tissue Artefact Requires Compensation When Estimating Joint Kinematics?
Authors: Dumas Raphaël , Camomilla Valentina , Bonci Tecla , Chèze Laurence , Cappozzo Aurelio
Published: April 2015

When joint kinematics is analyzed using noninvasive stereophotogrammetry, movements of the skin markers relative to the underlying bone are regarded as artefacts (soft tissue artefact (STA)). Recent literature suggests that an appropriate estimation of joint kinematics may be obtained by compensating for only a portion of the STA, but no evidence for this case has been reported, and which portion of the STA should be selected remains an issue. The aim of this study was to fill this gap. A modal approach was used to represent the STA. This resulted in a series of additive components (modes) and in the possibility to select a subset of them. The following STA definitions were used: individual skin marker displacement (MD), marker-cluster geometrical transformation (GT), and skin envelope shape variation (SV). An STA approximation for each of the three definitions was obtained by ordering modes on the basis of their contribution to the total STA energy and truncating the relevant series at 90% of it. A fourth approximation was obtained when the GT definition was used, by selecting the modes that represented the marker-cluster rigid transformation (i.e., three translation and three rotation modes). The different STA approximations were compared using data obtained during the stance phase of running of three volunteers carrying both pin and skin markers. The STA was measured and knee joint kinematics estimated using four skin marker datasets compensated for the above-mentioned STA approximations. Accuracy was assessed by comparing results to the reference kinematics obtained using pin markers. The different approximations resulted in different numbers of modes. For joint angles, the compensation efficiency across the STA approximations based on an energy threshold was almost equivalent. The median root mean square errors (RMSEs) were below 1 deg for flexion/extension and 2 deg for both abduction/adduction and internal/external rotation. For the joint displacements, the compensation efficiency depended on the STA approximation. Median RMSEs for anterior/posterior displacement ranged from 1 to 4 mm using either MD, GT, or SV truncated series. The RMSEs were virtually null when the STA was approximated using only the GT rigid modes. This result, together with the limited number of modes used by this approximation (i.e., three translations and three rotations of the marker-cluster), makes the STA rigid component and a good candidate for designing an STA model to be incorporated in an enhanced bone pose estimator.
The Influence of Imperfections and Nonlinearities on the Failure and B2 Stress Index of Thin-Walled Pipes
Authors: Schau Henry , Mkrtchyan Lilit , Geier Michael
Published: April 2015

The effects of imperfections and nonlinearities on the failure mode and the B2 stress index of thin-walled straight pipes are investigated with finite element (FE) analyses. The analyses were performed for pipes made of an ideal elastic–plastic material and the austenitic steel X6CrNiNb18-10. The B2 index is calculated from the instability bending moments obtained by limit load analyses. The effects of initial imperfections as well as the D/t-ratio and the yield stress on the B2 stress index are studied. As a first result, it is noted that thin-walled straight pipes and imperfections fail due to local plastic buckling. Further analyses show that the type of imperfections, the ovality, the D/t-ratio, and the yield stress have significant influences on the B2 index. The obtained B2 indices for thin-walled straight pipes with D/t > 40 and possible technical imperfections are considerably higher than 1.0. The results have been compared with those of other investigations.
Nucleation of diindenoperylene and pentacene at thermal and hyperthermal incident kinetic energies
Authors: Kish Edward R. , Desai Tushar V. , Greer Douglas R. , Woll Arthur R. , Engstrom James R.
Published: April 2015

The authors have examined the nucleation of diindenoperylene (DIP) on SiO2 employing primarily atomic force microscopy and focusing on the effect of incident kinetic energy employing both thermal and supersonic sources. For all incident kinetic energies examined (Ei = 0.09–11.3 eV), the nucleation of DIP is homogeneous and the dependence of the maximum island density on the growth rate is described by a power law. A critical nucleus of approximately two molecules is implicated by our data. A re-examination of the nucleation of pentacene on SiO2 gives the same major result that the maximum island density is determined by the growth rate, and it is independent of the incident kinetic energy. These observations are readily understood by factoring in the size of the critical nucleus in each case, and the island density, which indicates that diffusive transport of molecules to the growing islands dominate the dynamics of growth in the submonolayer regime.
Effectiveness of digital infrared thermal imaging in detecting lower extremity deep venous thrombosis
Authors: Deng Fangge , Tang Qing , Zeng Guangqiao , Wu Hua , Zhang Nuofu , Zhong Nanshan
Published: April 2015

Purpose:

The authors aimed to determine the effectiveness of infrared thermal imaging (IRTI) as a novel, noninvasive technique in adjunctive diagnostic screening for lower limb deep venous thrombosis (DVT).

Methods:

The authors used an infrared thermal imaging sensor to examine the lower limbs of 64 DVT patients and 64 healthy volunteers. The DVT patients had been definitively diagnosed with either Doppler vascular compression ultrasonography or angiography. The mean area temperature (T_area) and mean linear temperature (T_line) in the region of interest were determined with infrared thermal imaging. Images were evaluated with qualitative pseudocolor analysis to verify specific color‐temperature responses and with quantitative temperature analysis. Differences in T_area and T_line between the DVT limb and the nonaffected limb in each DVT patient and temperature differences (TDs) in T_area (TDarea) and T_line (TDline) between DVT patients and non‐DVT volunteers were compared.

Results:

Qualitative pseudocolor analysis revealed visible asymmetry between the DVT side and non‐DVT side in the presentation and distribution characteristics (PDCs) of infrared thermal images. The DVT limbs had areas of abnormally high temperature, indicating the presence of DVT. Of the 64 confirmed DVT patients, 62 (96.88%) were positive by IRTI detection. Among these 62 IRTI‐positive cases, 53 (82.81%) showed PDCs that agreed with the DVT regions detected by Doppler vascular compression ultrasonography or angiography. In nine patients (14.06%), IRTI PDCs did not definitively agree with the DVT regions established with other testing methods, but still correctly indicated the DVT‐affected limb. There was a highly significant difference between DVT and non‐DVT sides in DVT patients (P < 0.01). The TDarea and TDline in non‐DVT volunteers ranged from 0.19 ± 0.15 °C to 0.21 °C ± 0.17 °C; those in DVT patients ranged from 0.86 °C ± 0.71 °C to 1.03 °C ± 0.79 °C (P < 0.01).

Conclusions:

Infrared thermal imaging can be effectively used in DVT detection and adjunctive diagnostic screening because of its specific infrared PDCs and TDs values.
The emergence of nonuniform spatiotemporal fractionation schemes within the standard BED model
Authors: Unkelbach Jan , Papp Dávid
Published: April 2015

Purpose:

Nonuniform spatiotemporal radiotherapy fractionation schemes, i.e., delivering distinct dose distributions in different fractions can potentially improve the therapeutic ratio. This is possible if the dose distributions are designed such that similar doses are delivered to normal tissues (exploit the fractionation effect) while hypofractionating subregions of the tumor. In this paper, the authors develop methodology for treatment planning with nonuniform fractions and demonstrate this concept in the context of intensity‐modulated proton therapy (IMPT).

Methods:

Treatment planning is performed by simultaneously optimizing (possibly distinct) IMPT dose distributions for multiple fractions. This is achieved using objective and constraint functions evaluated for the cumulative biologically equivalent dose (BED) delivered at the end of treatment. BED based treatment planning formulations lead to nonconvex optimization problems, such that local gradient based algorithms require adequate starting positions to find good local optima. To that end, the authors develop a combinatorial algorithm to initialize the pencil beam intensities.

Results:

The concept of nonuniform spatiotemporal fractionation schemes is demonstrated for a spinal metastasis patient treated in two fractions using stereotactic body radiation therapy. The patient is treated with posterior oblique beams with the kidneys being located in the entrance region of the beam. It is shown that a nonuniform fractionation scheme that hypofractionates the central part of the tumor allows for a skin and kidney BED reduction of approximately 10%–20%.

Conclusions:

Nonuniform spatiotemporal fractionation schemes represent a novel approach to exploit fractionation effects that deserves further exploration for selected disease sites.
Vigorous-Intensity Physical Activity is Associated with Metabolic Syndrome Among the Chinese Middle-Aged Population: A Cross-Sectional Study
Authors: Hu Bo , Liu Xiaoyu , Wang Chenggang , Yin Sufeng , Yu Liqun , Zhang Tianzhe , Wu Jianhui , Chen Yinping , Zheng Yao , Feng Fumin
Published: April 2015

Objective:

To examine the association and relative contribution of different levels of physical activity (PA) with metabolic syndrome (MS).

Methods:

The cluster sampling method was used to recruit 8,750 communitybased individuals between 40 and 60 years of age. MS was defined according to the International Diabetes Federation, 2005. PA was estimated with the International Physical Activity Questionnaire, and three levels of PA (low, moderate, vigorous) were used to classify the individuals. The risk factors of MS were comprehensively collected, and logistic regression methods were used to measure the association between PA and MS. Population-attributable risks and their 95% confidence intervals (CI) were calculated based on the regression model.

Results:

Approximately 30.4% (2,661) of the participants were MS patients. The percentage of individuals with vigorous levels of PA was 46.2% and 43.5% and with low levels of PA was 11.3% and 11.3% in non-MS and MS group, respectively. Individuals with vigorous PA had an odds ratio (OR) of 0.78 (95% CI: 0.66, 0.91) for MS compared with those with low PA, and the OR for individuals with moderate PA was 0.85 (95% CI: 0.73, 1.01). Moderate and vigorous PA levels decreased risk of MS by 18.3%, with approximately 11% of that decrease due to vigorous PA.

Conclusions:

Vigorous PA levels were consistently associated with a reduced risk of MS; however, a protective role of moderate PA was not found. The population-attributable risk for vigorous PA was about 11% for all MS risk factors.