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Mitochondrial DNA (mtDNA) mutations accumulate in both mitotic and post-mitotic somatic tissues of normal individuals with age. They clonally expand within individual cells and cause mitochondrial dysfunction. In contrast, in patients with inherited disease-causing mtDNA mutations the mutation load decreases in mitotic tissues over time, whereas the mutations load in post-mitotic tissues remains relatively stable. The mechanisms underlying this decrease in mitotic tissues, and whether mitochondrial function is restored at the tissue level are unknown. Here, using a combination of homogenate tissue and single crypt/muscle fibre pyrosequencing we have shown a decrease in the mutation load of the germline heteroplasmic m.5024C>T mutation in multiple mitotic tissues of a mouse model of inherited mitochondrial disease (C5024T mice). We have then usedin silicopredictions to model the cellular dynamics of mtDNA mutation load in mitotic and post mitotic tissues. We demonstrate that: (1) the rate of m.5024C>T decrease correlates with the rate of tissue turnover; (2) the mutation load decrease is not associated with changes in overall cellular proliferation and apoptosis within the mitotic colonic epithelium; instead, it could be due to an upper limit of m.5024C>T load in stem cell populations; (3) the m.5024C>T mutation load is maintained in post-mitotic tissues over time with a consistent load amongst individual muscle fibres; (4)in silicomodelling supports a scenario where genetic drift is accelerated in mitotic tissues by high levels of mtDNA replication coupled with mtDNA segregation at cell division. This study has advanced our understanding of the dynamics of mtDNA mutations and phenotype development in patients with mtDNA disease.Author SummaryHealthy individuals randomly accumulate pathogenic mtDNA mutations with age in dividing cells, causing mitochondrial dysfunction. Interestingly, patients with mitochondrial disease show a relative decrease in the loads of inherited mtDNA mutations in some dividing cells over time. The mechanisms underlying this decrease are unknown. Here we show a decrease in the load of the germline heteroplasmic m.5024C>T mutation in dividing cells and tissues of a mouse model of mitochondrial disease. In contrast, the mutation load in non-dividing cells and tissue remains stable. Our data are consistent with the hypothesis that a higher frequency of mtDNA replication in dividing cells, coupled with stem cells having an upper tolerance limit for m.5024C>T, causes an overall decrease in m.5024C>T load at the tissue level.

Developmental hypoxia has profound and persistent effects on the vertebrate cardiovascular system, but the nature, magnitude, and long-term outcome of the hypoxic consequences are species specific. Here we aim to identify common and novel cardiovascular responses among vertebrates that encounter developmental hypoxia, and we discuss the possible medical and ecological implications.

Funder: British Heart Foundation; Id: http://dx.doi.org/10.13039/501100000274, Insufficient oxygen supply (hypoxia) during fetal development leads to cardiac remodeling and a predisposition to cardiovascular disease in later life. Previous work has shown hypoxia causes oxidative stress in the fetal heart and alters the activity and expression of mitochondrial proteins in a sex-dependent manner. However, the functional effects of these modifications on mitochondrial respiration remain unknown. Furthermore, while maternal antioxidant treatments are emerging as a promising new strategy to protect the hypoxic fetus, whether these treatments convey similar protection to cardiac mitochondria in the male or female fetus has not been investigated. Therefore, using an established rat model, we measured the sex-dependent effects of gestational hypoxia and maternal melatonin treatment on fetal cardiac mitochondrial respiration, reactive oxygen species (ROS) production, and lipid peroxidation. Pregnant Wistar rats were subjected to normoxia or hypoxia (13% oxygen) during gestational days (GDs) 6-20 (term ~22 days) with or without melatonin treatment (5 µg/ml in maternal drinking water). On GD 20, mitochondrial aerobic respiration and H2 O2 production were measured in fetal heart tissue, together with lipid peroxidation and citrate synthase (CS) activity. Gestational hypoxia reduced maternal body weight gain (p < .01) and increased placental weight (p < .05) but had no effect on fetal weight or litter size. Cardiac mitochondria from male but not female fetuses of hypoxic pregnancy had reduced respiratory capacity at Complex II (CII) (p < .05), and an increase in H2 O2 production/O2 consumption (p < .05) without any changes in lipid peroxidation. CS activity was also unchanged in both sexes. Despite maternal melatonin treatment increasing maternal and fetal plasma melatonin concentration (p < .001), melatonin treatment had no effect on any of the mitochondrial parameters investigated. To conclude, we show that gestational hypoxia leads to ROS generation from the mitochondrial electron transport chain and affects fetal cardiac mitochondrial respiration in a sex-dependent manner. We also show that maternal melatonin treatment had no effect on these relationships, which has implications for the development of future therapies for hypoxic pregnancies.

Changes in free-roaming dog population size are important indicators of the effectiveness of dog population management. Assessing the effectiveness of different management methods also requires estimating the processes that change population size, such as the rates of recruitment into and removal from a population. This is one of the first studies to quantify the size, rates of recruitment and removal, and health and welfare status of free-roaming dog populations in Europe. We determined the size, dynamics, and health status of free-roaming dog populations in Pescara, Italy, and Lviv, Ukraine, over a 15-month study period. Both study populations had ongoing dog population management through catch-neuter-release and sheltering programmes. Average monthly apparent survival probability was 0.93 (95% CI 0.81-1.00) in Pescara and 0.93 (95% CI 0.84-0.99) in Lviv. An average of 7 dogs km-2 were observed in Pescara and 40 dogs km-2 in Lviv. Per capita entry probabilities varied between 0.09 and 0.20 in Pescara, and 0.12 and 0.42 in Lviv. In Lviv, detection probability was lower on weekdays (odds ratio: 0.74, 95% CI 0.53-0.96) and higher on market days (odds ratio: 2.58, 95% CI 1.28-4.14), and apparent survival probability was lower in males (odds ratio: 0.25, 95% CI 0.03-0.59). Few juveniles were observed in the study populations, indicating that recruitment may be occurring by movement between dog subpopulations (e.g. from local owned or neighbouring free-roaming dog populations), with important consequences for population control. This study provides important data for planning effective dog population management and for informing population and infectious disease modelling. The results emphasise the importance of dog population management efforts that encourage responsible ownership through reduced abandonment and cover the entire city to reduce the risk of dog movement between sections of the city hindering management efforts.

SUMMARYHuman pluripotent stem cells (hPSCs) are a powerful tool for disease modelling and drug discovery, especially when access to primary tissue is limited, such as in the brain. Current neuronal differentiation approaches use either small molecules for directed differentiation or transcription-factor-mediated programming. In this study we coupled the overexpression of the neuralising transcription factor Neurogenin2 (Ngn2) with small molecule patterning to differentiate hPSCs into lower induced Motor Neurons (liMoNes). We showed that this approach induced activation of the motor neuron (MN) specific transcription factor Hb9/MNX1, using anHb9::GFP-reporter line, with up to 95% of cells becoming Hb9::GFP+. These cells acquired and maintained expression of canonical early and mature MN markers. Molecular and functional profiling revealed that liMoNes resembled bona fide hPSC-derived MN differentiated by conventional small molecule patterning. liMoNes exhibited spontaneous electrical activity, expressed synaptic markers and formed contacts with muscle cells in vitro. Pooled, multiplex single-cell RNA sequencing on 50 cell lines revealed multiple anatomically distinct MN subtypes of cervical and brachial, limb-innervating MNs in reproducible quantities. We conclude that combining small molecule patterning with Ngn2 can facilitate the high-yield, robust and reproducible production of multiple disease-relevant MN subtypes, which is fundamental in the path to propel forward our knowledge of motoneuron biology and its disruption in disease.

Employers provide their interpretation of the meaning of communication skills in this qualitative study of 22 managers. Employers understand written communication to be types of documents, a way to write, and a mode of communication. Oral communication skills mean a style of interacting, presenting, and conducting meetings. Visual communication skills were understood to be data visualization or nonverbal communication. Electronic communication was interpreted as email. The findings contribute to closing-the-gap research by highlighting areas where meaning converges for employers and instructors. Faculty members in communication disciplines can incorporate these findings into their course design and learning outcome discussions.

One of the hallmarks of aging is an accumulation of cells with defects in oxidative phosphorylation (OXPHOS) due to mutations of mitochondrial DNA (mtDNA). Rapidly dividing tissues maintained by stem cells, such as the colonic epithelium, are particularly susceptible to accumulation of OXPHOS defects over time; however, the effects on the stem cells are unknown. We have crossed a mouse model in which intestinal stem cells are labelled with EGFP (Lgr5‐EGFP‐IRES‐creERT2) with a model of accelerated mtDNA mutagenesis (PolgA mut/mut) to investigate the effect of OXPHOS dysfunction on colonic stem cell proliferation. We show that a reduction in complex I protein levels is associated with an increased rate of stem cell cycle re‐entry. These changes in stem cell homeostasis could have significant implications for age‐associated intestinal pathogenesis., Age‐associated mitochondrial DNA mutations accumulate in the colonic epithelial crypts of the PolgA mut/mut and PolgA +/mut mice. This leads to a reduction in mitochondrial complex I and IV protein levels. Stem cells with complex I defects re‐enter the cell cycle 20% more frequently than those with normal complex I levels.

Oxidative phosphorylation (OXPHOS) defects caused by somatic mitochondrial DNA (mtDNA) mutations increase with age in human colorectal epithelium and are prevalent in colorectal tumours, but whether they actively contribute to tumorigenesis remains unknown. Here we demonstrate that mtDNA mutations causing OXPHOS defects are enriched during the human adenoma/carcinoma sequence, suggesting they may confer a metabolic advantage. To test this we deleted the tumour suppressor Apc in OXPHOS deficient intestinal stem cells in mice. The resulting tumours were larger than in control mice due to accelerated cell proliferation and reduced apoptosis. We show that both normal crypts and tumours undergo metabolic remodelling in response to OXPHOS deficiency by upregulating the de novo serine synthesis pathway (SSP). Moreover, normal human colonic crypts upregulate the SSP in response to OXPHOS deficiency prior to tumorigenesis. Our data show that age-associated OXPHOS deficiency causes metabolic remodelling that can functionally contribute to accelerated intestinal cancer development.

A study of 959 black and white women shows that the normal range for 24-h urine calcium excretion in white women is 30–300 mg and 10–285 mg in black women. Clinical laboratories use a normal range for 24-h urine calcium excretion of 100–300 mg; there is a need for them to update their age- and race-specific ranges. Recommendations for a normal range for 24-h urine calcium vary from a low of 50 mg to a high of 400 mg; most “laboratory normal ranges” based on older literature are incorrect. The objective of this analysis is to define a normal range for young women age 25–45 years and older women age 55–90 years, white and black, for 24-h urine calcium and calcium/creatinine ratio, and to examine the relationship between 24-h urine calcium, calcium absorption, and vitamin D metabolites. Data from 3 studies was collected on 959 normal black and white women, ages 25–87 years, for 24-h urine calcium, creatinine, calcium intake, serum 25-hydroxyvitamin D (25OHD),1,25 dihydroxyvitamin D (1,25(OH)2D), and calcium absorption. Urine calcium and creatinine were measured on an auto-analyzer. Calcium absorption was measured by a single isotope method. Serum 25OHD and 1,25(OH)2D were measured by competitive protein binding assay or radioimmunoassay. Because 24-h urine calcium did not fit a normal distribution, non-parametric methods were used to determine the 95% reference interval (RI) and 90% non-parametric confidence intervals (CI) calculated for groups. The 95% reference intervals for 24-h urine calcium for women were as follows: black older 7–225 mg, black younger 8–285 mg; white older 37–275 mg, and white younger 23–287 mg. In older white women, 24-h urine calcium was significantly correlated with serum 1,25(OH)2 D, r = 0.23, p < 0.001, calcium intake r = 0.12, p = 0.001, and calcium absorption r = 0.18, p = 0.003, but not serum 25OHD r = 0.07, p = 0.06. The normal reference interval for 24-h urine calcium for black women is lower than white women. Twenty-four-hour urine calcium was correlated with serum 1,25(OH)2 D calcium intake and calcium absorption, but not serum 25OHD. This range will be useful clinically for defining hypercalciuria and for following patients on vitamin D and calcium treatment.

The purpose of this article is to demonstrate that higher education institutions should change their Faculty Codes of Conduct to reflect workplace bullying as a form of unacceptable harassment. The...

Church organizations provide a unique perspective from which to study participation and paradox. While participatory paradoxes to date focus on paradoxes created by leaders for members, it is important to remember that organizing is co-constructed between leaders and members. It is, therefore, also important to study how members create paradoxes for leaders. Church organizations shed light on the embedded nature of paradoxes. The purpose of this study is to explore member-created leadership paradoxes during decision-making events in a church organization. Qualitative methods guided this research. Three member-created paradoxes were discovered: the organizing paradox, the information paradox, and the involvement paradox. Future research should study members of multiple churches to determine how paradoxes in participation exist within different organizations.

Pharmacological inhibition of the sonic hedgehog (SHH) pathway can be beneficial against certain cancers but detrimental in others. Adamantinomatous craniopharyngioma (ACP) is a relevant pituitary tumour, affecting children and adults, that is associated with high morbidity and increased mortality in long-term follow-up. We have previously demonstrated overactivation of the SHH pathway in both human and mouse ACP. Here, we show that this activation is ligand dependent and induced by the expression of SHH protein in a small proportion of tumour cells. We investigate the functional relevance of SHH signalling in ACP through MRI-guided preclinical studies using an ACP mouse model. Treatment with vismodegib, a clinically approved SHH pathway inhibitor, results in a significant reduction in median survival due to premature development of highly proliferative and vascularised undifferentiated tumours. Reinforcing the mouse data, SHH pathway inhibition in human ACP leads to a significant increase in tumour cell proliferation both ex vivo, in explant cultures, and in vivo, in a patient-derived xenograft model. Together, our results demonstrate a protumourigenic effect of vismodegib-mediated SHH pathway inhibition in ACP.

Mitochondrial respiratory chain deficiency and mitochondrial DNA deletions are reported in substantia nigra neurons from healthy aged and Parkinson's disease cases, with extensive neuronal loss only seen in the latter. This study aimed to understand the pathological relevance of mitochondrial defects for neuronal survival. Using post-mortem human midbrain, substantia nigra neurons exposed to different types of mitochondrial defects (including mitochondrial DNA point mutations, single and multiple deletions) were compared to neurons from healthy aged and Parkinson's disease cases (either sex) at a single neuronal level. We identified mitochondrial deficiencies in all cases, though these deficiencies were more severe in the mitochondrial disease patients with multiple deletions. A significant reduction in TFAM expression was detected in Parkinson's disease compared to cases with other mitochondrial defects. Higher mitochondrial DNA copy number was detected in healthy aged neurons, despite a deletion level equivalent to Parkinson's disease. Our data support that in individuals with pathogenic mitochondrial defects, neurons respond to mitochondrial defect to survive and such an adaptation may involve TFAM.

Friedreich’s ataxia (FRDA) is an incurable autosomal recessive neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin due to an intronic GAA-repeat expansion in the FXN gene. We report the therapeutic efficacy of transplanting wild-type mouse hematopoietic stem and progenitor cells (HSPCs) into the YG8R mouse model of FRDA. In the HSPC-transplanted YG8R mice, development of muscle weakness and locomotor deficits was abrogated as was degeneration of large sensory neurons in the dorsal root ganglia (DRGs) and mitochondrial capacity was improved in brain, skeletal muscle, and heart. Transplanted HSPCs engrafted and then differentiated into microglia in the brain and spinal cord and into macrophages in the DRGs, heart, and muscle of YG8R FRDA mice. We observed the transfer of wild-type frataxin and Cox8 mitochondrial proteins from HSPC-derived microglia/macrophages to FRDA mouse neurons and muscle myocytes in vivo. Our results show the HSPC-mediated phenotypic rescue of FRDA in YG8R mice and suggest that this approach should be investigated further as a strategy for treating FRDA.

Creepage, a typical phenomenon in the hemming process, can be defined as undesired roll-in of the panel at the bending line. Creepage also reduces the final panel width and makes the hemming radius larger. In this study, experimental observations are reported, and a finite element model, based on the LS-DYNA® two dimensional plane strain solid formulation, is utilized to study the mechanics of how the hem flange bends and folds during the hemming process. A novel hemming process incorporating a counteraction force is proposed in order to prevent the creepage phenomenon during the hemming process. An experimental hemming tool was designed according to this concept, and optimization of the tooling geometry was carried out utilizing the finite element model. An experimental study was conducted to confirm that the new hemming process can prevent creep be employed to help retain a sharp radius during flanging operation.

During high-speed sheet metal forming processes, the speed at which the work piece contacts the die tooling is on the order of hundreds of meters per second. When the impact is concentrated over a small contact area, the resulting contact stress can compromise the structural integrity of the die tooling. Therefore, it is not only important to model the behavior of the workpiece during the high-speed sheet metal forming process, but also important to predict accurately the associated workpiece/tooling interface loads so that engineers can more confidently propose robust die tooling designs. The foundation to accurate predictions of contact stress on die tooling is a reliable contact model within the context of a finite element simulation. In literature, however, there exists no comprehensive guideline for establishing a contact model for high-speed sheet metal forming processes using the finite element method. In this paper, mathematically justified contact model recommendations are offered for the electrohydraulic forming (EHF) process.

The HPRS-103 strain of avian retrovirus is the prototype of subgroup J avian leukosis virus (ALV-J) and causes myeloid leukosis in meat-type chickens. Using immunohistochemical detection of the viral groupspecific antigen (Gag) we have previously demonstrated that the induction of myeloid leukosis by ALV-J is associated with viral tropism for myelomonocytic cells. In this paper we describe an in situ hybridization (ISH) technique using digoxigenin (DIG)-labelled probes for detecting RNA transcripts in tissues from chickens infected with avian leukosis viruses (ALV) of subgroups J (HPRS-103 strain) and A (RAV-1 strain). Virus-specific RNA was detected mainly in the heart, kidney, proventriculus and adrenal in locations similar to those of the Gag protein. Viral gene expression could not be detected in the bone marrow or tumour tissues using this test. Higher levels of viral gene expression in the bursa of Fabricius infected with RAV-1, but not with HPRS-103, might help explain the inability of the latter virus to induce lymphoid leukosis.

Using a rat model of binge drinking during the third trimester of pregnancy, we investigated neural markers of glutamatergic activity and cell death during the acute post-ethanol withdrawal period in rats. Ethanol-exposed animals demonstrated increases in markers for glutamatergic activity (NMDA receptors 1 and c-Fos immunoreactivity) and apoptotic cell death (caspase-3 immunoreactivity and cells having fragmented or condensed nuclei identified by Hoechst 33342 staining) in the CA1 and CA3 subfields and dentate gyrus of the hippocampus. Ethanol exposure also increased markers for glutamatergic activity and apoptotic cell death in the prefrontal cortex, dorsal striatum, somatosensory cortex, and motor cortex. The facts that markers for glutamatergic activity and cell death were both elevated in the areas examined, and the magnitudes of the elevation in the two sets of markers correlated negatively, are consistent with a causal link between the two. The results support the hypothesis that NMDA-mediated excitotoxic cell death is involved in neuropathological events that follow ethanol exposures.

Retirement is an expected phase of life that is made meaningful through social discourses such as master narratives. This study identified and explored a master narrative of retirement. Eighty-four individuals were interviewed representing four work experience phases. A thematic analysis revealed a master narrative of retirement that shaped expectations for retirement. Participants consistently narrated retirement as the ultimate marker of individual success and freedom. Two fractures appeared in this master narrative: the freedom/routine fracture and the individual responsibility/universal expectations fracture. These fractures created tension within the master narrative of retirement. This study has implications for social class as well as implications for the ways in which master narratives are interwoven into the cultural fabric of society.

In the current study the authors investigate victims' response to a natural disaster crisis event. Crisis communication research has often considered organizations, but neglected the voice of the victims. Similarly, most crisis research emphasizes the negative outcomes of crisis. Positive communication research and sensemaking theory provide insight into the experiences of crisis victims. Twenty-nine individuals were interviewed from one community in Western Kentucky following a massive ice storm that occurred during January 2009. The remembering emphasis of sensemaking was salient in this study. Victims remembered their overall experience through positive terms and positive interpersonal communication. Communities and organizations alike can use this research to consider how their members may respond to crises and create messages based on these results.

Pre-bending is a critical process required prior to hydroforming. The bending has an effect on the tube thickness and strain which will use up a portion of the formability of the as-received tube. To compensate for this loss of formability, a multi-objective optimization method was applied to improve the hydroforming process after pre-bending. A multi-objective genetic algorithm (MOGA) and Kriging surrogate model were used to optimize the loading path. The Kriging model was used to replace the finite element simulation in constraint handling. The optimal loading parameters in the hydroforming process were obtained for a tube that was previously bent 90°, and showed an improvement in reducing the corner radii of the part at the extrados and intrados of the bend (8.73 mm and 11.24 mm for the extrados and intrados of the bend, respectively). The corresponding corner fill expansion (CFE) was improved by 16.7% (or 1.79 mm) compared to the maximum expansion of 10.73 mm obtained experimentally.

Prior to performing an MRI-guided breast biopsy, the radiologist has to locate the suspect lesion with the breast compressed between rigid plates. However, the suspect lesion is typically identified from a diagnostic MRI exam with the breast hanging freely under the force of gravity. There are several challenges associated with localizing suspect lesions including, patient positioning, the visibility of the lesion may fade after contrast injection, menstrual cycles, and lesion deformation. Researchers have developed finite element analysis (FEA) methodologies that simulate breast compression with the intent of reducing these challenges. In this paper, we constructed a patient-specific finite element (FE) breast model from diagnostic MR images. In addition, we constructed surfaces corresponding to the biopsy MR volume and used them to deform the FE breast mesh. The predicted results suggest that the FE breast model, in its uncompressed configuration, can be compressed to replicate the perimeter of the biopsy MR volume. The simulated lesion displacement was within 3 mm of its actual position.

The objective of this study is to determine the influence of material anisotropy and trimming method on the total elongation of the trimmed edge of DP500 sheet steel. For various orientations, experimental analysis is carried out on rectangular shaped tensile test specimens featuring a polished edge on one side and a trimmed edge on the other side. It is shown that the total elongation in DP500 steel exhibits significant sensitivity to (1) specimen orientation with respect to rolling direction, and (2) trimming method employed. In particular, difference in total elongation between longitudinal and transverse orientations become more pronounced with increasing trim clearance for conventionally trimmed samples. Total elongation anisotropy, however, can be significant even at small trim clearances and when sheared surface of the blank has relatively good quality without the burr which is the case for samples trimmed by the technology with offal support and dulled upper trim edge. The observations provided herein may be instrumental in contributing to meaningful explanations for unexpected edge cracking problems observed in some DP500 stamping cases. Recommendations for manufacturing best practices are offered.

The underlying principles of water’s equation of state (ES) and its associated pressure–volume–temperature (PVT) relationship, are employed for the purpose of producing “ultra-high” pressure within the closed volume of a thick-walled metal tube, resulting in a new and innovative hydroforming process. The process, called “Closed-Volume Thermally Activated” (C V TA) Tube Hydroforming, involves conducting a high level of heat through the walls of a thick-walled, metallic, water-containing closed tube. Experimental validation of the concept is presented, and potential applications are discussed. This work represents a break-through in manufacturing technology, which, when further developed, is expected to enable manufacturers to expand significantly their manufacturing capability.

A novel device for obtaining pulling and holding forces for draw bead tooling on inclined binder surfaces has been developed. A mechanical design featuring two load cells, a male–female draw bead set, translation and rotation degrees of freedom, and a screw-driven clamping system has been incorporated into a standard tensile test machine. On a real time basis, pulling force, holding force, and draw-in displacement are downloaded directly into a PC for data processing. Results for the sheet metal materials considered confirm quantitatively that the binder angle significantly influences the draw bead pulling force. For example, for the materials, bead penetrations, and bead geometries studied, the pulling force at a 20° binder angle ranged from 55% to 96% of that corresponding to a 0° binder angle. The pulling force data are useful for the purpose of theoretical and numerical draw bead model calibration. The proposed experimental system, called the Oakland University Angle Draw Bead Simulation (OU-ADBS) test, represents a significant breakthrough in draw bead simulation technology due to its relatively low cost and clever design.

A new experimental approach for determining the sheet metal flow stress curve for diffuse necking deformation through the hydraulic bulge expansion (HBE) test is introduced. For this approach, a flat sheet of metal is bulged under the load of hydraulic pressure within the confines of a rigid binder/die tool set of circular die opening. The hydraulic pressure and volume flow rate of the pressurized water entering the die cavity are recorded in real time. Operating under the assumption of thin-walled pressure vessel behavior, the real time data are used to compute the flow stress curve for the material type considered. The novel aspect of the proposed technique is the use of water volume measurement for determining the radius of curvature of the expanding dome. An example flow stress curve for 1.0 mm thick DDQ cold rolled sheet steel is shown to be in good agreement with the flow stress curve obtained through the standard uniaxial tension test. One key advantage of this proposed method is that the analyst may determine the diffuse necking portion of the flow stress curve without employing cumbersome techniques associated with uniaxial tensile test methods. Two disadvantages of the proposed method are the uncertainty associated with having to assume a yield surface, and the error associated with having to assume membrane behavior in the work piece. The introduction of this new method will increase researchers’ access to practical methods for obtaining sheet metal flow stress curves.

Experiments were conducted to measure ice film thickness on a cryogenic mirror and quartz crystal microbalance under high vacuum conditions using an expanded multiple-beam interferometer, and results were compared with previous experiments [1].

The brittleness and resistance to deformation of rubber/bitumens and of sand asphalts made with rubber/bitumens have been investigated and compared with results obtained with similar materials not containing rubber. The brittleness tests were carried out by subjecting the materials to an imposed rate of tensile strain at 0°, the stress and strain being measured throughout the test. The deformation characteristics were measured in a wide-gap concentric-cylinder apparatus, the tests on bitumens being conducted at 25° and those on sand asphalts at 45°. The results show that the incorporation of rubber produces a material which displays, under the test conditions used, a marked increase in resistance to deformation, simultaneously with a reduced brittleness at low temperatures. It is concluded that, although some free rubber is clearly present as a separate phase, the modification of the normal bitumen properties is due at least in part to dispersion of the rubber on a molecular scale.

The ability of bacteriophage to persist in the phyllosphere for extended periods is limited by many factors, including sunlight irradiation, especially in the UV zone, temperature, desiccation, and exposure to copper bactericides. The effects of these factors on persistence of phage and formulated phage (phage mixed with skim milk) were evaluated. In field studies, copper caused significant phage reduction if applied on the day of phage application but not if applied 4 or 7 days in advance. Sunlight UV was evaluated for detrimental effects on phage survival on tomato foliage in the field. Phage was applied in the early morning, midmorning, early afternoon, and late evening, while UVA plus UVB irradiation and phage populations were monitored. The intensity of UV irradiation positively correlated with phage population decline. The protective formulation reduced the UV effect. In order to demonstrate direct effects of UV, phage suspensions were exposed to UV irradiation and assayed for effectiveness against bacterial spot of tomato. UV significantly reduced phage ability to control bacterial spot. Ambient temperature had a pronounced effect on nonformulated phage but not on formulated phages. The effects of desiccation and fluorescent light illumination on phage were investigated. Desiccation caused a significant but only slight reduction in phage populations after 60 days, whereas fluorescent light eliminated phages within 2 weeks. The protective formulation eliminated the reduction caused by both of these factors. Phage persistence was dramatically affected by UV, while the other factors had less pronounced effects. Formulated phage reduced deleterious effects of the studied environmental factors.

Magnesium doping is critically important in GaN device technology, since it provides the only viable method of producing layers with p-type conductivity. Electron probe microanalysis with wavelength dispersive x-ray spectrometry (WDX-EPMA) was used to measure magnesium atom concentrations in doped GaN films grown by metal organic vapour phase epitaxy (MOVPE). Our study compared the behaviour of a widely used magnesium source in MOVPE, bis(cyclopentadienyl) magnesium, when vaporized as a solid and as a proprietary two-phase source, Solution Cp2Mg™. The WDX-EPMA technique was capable of measuring [Mg] values in GaN layers at practically useful concentrations of 1019 cm−3 upwards. Excellent agreement in [Mg] values was obtained between [Mg] values measured by WDX-EPMA and the more widely used technique of secondary ion mass spectrometry (SIMS). A set of 12 GaN:Mg samples was studied by WDX-EPMA to investigate the dependence of [Mg] on the flow rate of the magnesium source into the MOVPE reactor, with other conditions held constant, including a growth set-point temperature of 1130 °C. These measurements suggested a solid solubility limit at ~1020 cm−3, consistent with previous studies. Up to a value of about half the saturation limit, [Mg] values were proportional to the magnesium source flow, and indicated magnesium atom incorporation from the gas phase with ~11% of the efficiency of gallium atoms. No systematic differences were seen between the behaviour of solid magnesocene and Solution Cp2Mg™. A more limited study of the temperature dependence of magnesium incorporation showed a reduction in incorporation of ~40% as the growth temperature was reduced from 1130 to 1090 °C, consistent with kinetic control. Selected GaN:Mg samples were studied by Hall measurements and high-resolution x-ray diffraction. This work showed no systematic structural degradation of GaN:Mg close to the magnesium solubility limit. Our most conductive sample had a hole concentration of 4.4 × 1017 cm−3, consistent with the expected generation of acceptors from only a small fraction of the magnesium atoms. We also discuss the relative capabilities of SIMS and WDX-EPMA in the context of analysing GaN:Mg samples. SIMS offers superior depth profiling capability and detection limits, whilst WDX-EPMA offers superior spatial resolution, non-destructive analysis, plus simultaneous imaging and cathodoluminescence spectroscopy.

A method to construct a forming limit corresponding to local necking is sought for aluminum alloy sheet metal. Through the manipulation of data collected from only one uniaxial tension test, a method for the calculation of a stress space forming limit for aluminum sheet metal is offered. Preserving a reasonable level of simplicity, the proposed method features the advantage of not relying upon assumptions about the material properties of the work piece. Such an advantage is realized by measuring the test specimen at the local neck region. Through finite element analysis, the proposed model is shown to be more accommodating to stamping cases where the effective strains exceed the diffuse necking limit. Because the proposed method is designed to circumvent the traditional difficulties associated with the detection and measurement of strains corresponding to local neck regions of aluminum alloys, it is offered as a tool for the formability analyst who desires to employ a reliable stress space forming limit model in their formability analysis. Although the introduction of the proposed method is motivated by the difficulties associated with determining the limiting strains in aluminum sheet metal, it is fully applicable to steel and other material types.

A new analytical (non-finite element) model for simulation of tubular hydroforming plane sections has been introduced. Unlike previous analytical models found in literature, the proposed model is capable of handling friction contact effects for near arbitrary cross sections through the employment of a new friction model. Although both burst pressure and final corner-fill radii can be predicted by the proposed model, the focus of the study is upon the final membrane hoop strain distribution. For both zero-friction and sticking-friction conditions, excellent agreement is observed among the proposed strain solutions and those from the finite element method for square die cross sections. For more arbitrarily defined die cross sections, reasonable agreement is observed among the proposed strain solutions and those from the finite element method. The proposed model has been introduced as a very early design/analysis tool. Therefore, it serves as a compliment to (not replacement for) the finite element method. If handled judiciously, use of the proposed model can lead to (1) reductions in the number of design iterations (2) reductions in manufacturing costs and (3) overall improvements in product quality.

A family of closed-form formulas for calculating minimum corner-fill radii in planar sections of tube hydroformed products is introduced. Corner forming limit diagrams relating the limiting major strain to the minimum corner-fill radius are introduced. The theory accounts for friction effects and accommodates regular shaped polygon die sections. This effort represents an exploration into a method for design and analysis of tube hydroforming processes without employing the finite element method and while using a closed form approach for capturing friction effects. Good agreement with experimental results is observed.

An assessment of the degree to which the assumptions influence the tubular hydroforming predictions from a strain rate-independent, four-node shell, explicit finite element model is made. Among a list of assumptions, it is found that the minimum element size, process time and contact algorithm must be provided to the recipient of a report on the finite element modeling of tubular hydroforming. It is found that the explicit, four-node, strain rate-independent finite element model: (1) underestimates the burst pressure for materials featuring higher strain rate sensitivity and (2) fails to produce an accurate strain distribution prediction.

It is generally understood that tensile stress loads lead to the shearing and/or expansion of micro voids in a metal specimen. Such deformation leads to stress concentrations that ultimately form the basis of the limiting strain capacity in a metal. Accordingly, a number of formability theories suggest that stress (not strain) is the key mechanism for ductile fracture. Motivated by such theories, an introduction to a special form of tubular hydroforming (THF) is put forth, where hydraulic pressure is introduced on both sides of the metal. Six different formability models are compared in light of their sensitivity to thickness normal stress (σ3) and other process variables associated with THF. It is shown that the models which capture the σ3 effect are most suitable for formability assessment for the double-sided high-pressure (DSHP) process. The stress space forming limit model is then employed in the context of a solid finite element model of a plane-strain THF expansion. The presence of the DSHP boundary condition is shown to lead to increased formability relative to that observed for the traditional single-sided high-pressure (SSHP) process. Research of the DSHP process may lead to discoveries of various avenues towards greater formability. Consequently, the design space currently available to those employing the SSHP process may be significantly increased through the DSHP process. Ultimately, such design space increase may result in lower product cost, greater customer enthusiasm and increased market share for those manufacturers who invest in the DSHP process. This work represents a preliminary numerical investigation into the DSHP process only. Issues of cost, time and fixture design are left untouched.