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The toxicity of non‐proteinogenic amino acids has been known for decades. Numerous reports describe their antimicrobial/anticancer potential. However, these molecules are often toxic to the host as well; thus, a synthetic lethality approach that reduces the dose of these toxins while maintaining toxicity can be beneficial. Here we investigate synthetic lethality between toxic amino acids, the retrograde pathway, and molecular chaperones. In Saccharomyces cerevisiae, mitochondrial retrograde (RTG) pathway activation induces transcription of RTG‐target genes to replenish alpha‐ketoglutarate and its downstream product glutamate; both metabolites are required for arginine and lysine biosynthesis. We previously reported that tolerance of canavanine, a toxic arginine derivative, requires an intact RTG pathway, and low‐dose canavanine exposure reduces the expression of RTG‐target genes. Here we show that only a few of the examined chaperone mutants are sensitive to sublethal doses of canavanine. To predict synthetic lethality potential between RTG‐target genes and chaperones, we measured the expression of RTG‐target genes in canavanine‐sensitive and canavanine‐tolerant chaperone mutants. Most RTG‐target genes were induced in all chaperone mutants starved for arginine; the same trend was not observed under lysine starvation. Canavanine exposure under arginine starvation attenuated and even reversed RTG‐target‐gene expression in the tested chaperone mutants. Importantly, under nearly all tested genetic and pharmacological conditions, the expression of IDH1 and/or IDH2 was induced. In agreement, idh1 and idh2 mutants are sensitive to canavanine and thialysine and show synthetic growth inhibition with chaperone mutants. Overall, we show that inhibiting molecular chaperones, RTG‐target genes, or both can sensitize cells to low doses of toxic amino acids. Take‐away: Canavanine sensitivity of chaperone mutants can be increased by deletion of IDH1 or IDH2, and thialysine sensitivity of chaperone mutants occurs with the deletion of IDH1, IDH2, CIT1, or CIT2; heat shock enhances these sensitivities. Our data suggest that mitochondrial isocitrate dehydrogenase plays a role in coping with proteotoxic stress. [ABSTRACT FROM AUTHOR]

The significance of reliable energy storage systems in spacecraft applications cannot be overstated, since they play a vital role in ensuring continuous power supply and prolonged mission durations. This research deals with the modeling of a hybrid multi-mission radioisotope thermoelectric generator (MMRTG)-lithium-ion (Li-ion) battery integrated energy storage system for spacecraft applications to combine the RTGs' long lifespan and reliability benefits alongside the Li-ion battery's rechargeability and high energy density to achieve a single energy unit. The investigation's main problem was exploring a power unit that improves the limitations of MMRTG and Li-ion batteries to achieve a highly efficient and reliable power supply for autonomous systems, such as a spacecraft. The proposed hybrid system comprises a 110 W/32 V RTG and a 3.6 V/43 Ah Li-ion battery connected to a DC motor through power converters. Results demonstrate the potential of the adopted hybrid energy system in improving the efficiency, reliability, and mission duration of spacecraft missions. The assessment of the hybrid energy system under various load conditions shows that the highest power peak of 3500 W was achieved at a load resistance of 1 Ω. Furthermore, the results show that the hybrid energy system output voltage at temperatures of 253 °K and 293 °K are relatively equal. However, the power cycle was wider and required a long time before dropping. [ABSTRACT FROM AUTHOR]

The significance of reliable energy storage systems in spacecraft applications cannot be overstated, since they play a vital role in ensuring continuous power supply and prolonged mission durations. This research deals with the modeling of a hybrid multi-mission radioisotope thermoelectric generator (MMRTG)-lithium-ion (Li-ion) battery integrated energy storage system for spacecraft applications to combine the RTGs’ long lifespan and reliability benefits alongside the Li-ion battery’s rechargeability and high energy density to achieve a single energy unit. The investigation’s main problem was exploring a power unit that improves the limitations of MMRTG and Li-ion batteries to achieve a highly efficient and reliable power supply for autonomous systems, such as a spacecraft. The proposed hybrid system comprises a 110 W/32 V RTG and a 3.6 V/43 Ah Li-ion battery connected to a DC motor through power converters. Results demonstrate the potential of the adopted hybrid energy system in improving the efficiency, reliability, and mission duration of spacecraft missions. The assessment of the hybrid energy system under various load conditions shows that the highest power peak of 3500 W was achieved at a load resistance of 1 Ω. Furthermore, the results show that the hybrid energy system output voltage at temperatures of 253 °K and 293 °K are relatively equal. However, the power cycle was wider and required a long time before dropping.

Alloy systems comprised of silicon with germanium, lead with tellurium, and bismuth with antimony have constituted a majority of thermoelectric applications during the last half-century. These legacy materials are primarily covalently bonded with a maximum ZT near one. Silicon–germanium alloys have provided the thermal to electrical conversion for many of NASA's radioisotope thermoelectric generator (RTG) configurations and for nearly all of its deep space and outer planetary flights, such as Pioneer I and II, Voyager I and 11, Ulysses, Galileo, and Cassini. The remarkable success of these materials and their respective devices is evidenced by the fact that there has never been a failure of the RTG systems even after over 1 billion cumulative mission-hours. The history of this alloy system as a thermoelectric conversion material spans over six decades and research to further improve its performance continues to this day. Si-Ge alloys have long been a mainstay of thermoelectric research because of a fortuitous combination of a sufficiently high melting temperature, reasonable energy band gap, high solubility for both n- and p-type dopants, and the fact that this alloy system exhibits complete miscibility in the solid state, which enable tuning of both electrical and thermal properties. This article reviews the history of silicon–germanium as a thermoelectric material and its use in NASA's RTG programs. Since the device technology is also a critical operational consideration, a brief review of some of the unique challenges imposed by the use in an RTG is also discussed. [ABSTRACT FROM AUTHOR]

Solid-state energy conversion through thermoelectric effects remains the technology of choice for space applications for which, their low energy conversion efficiency is largely outweighed by the reliability and technical requirements of the mission. Radioisotope thermoelectric generators (RTGs) enable the direct conversion of the heat released by nuclear fuel into the electrical power required to energize the scientific instruments. The optimization of the conversion efficiency is intimately connected to the performances of the thermoelectric materials integrated which are governed by the transport properties of these materials. Recent advances in the design of highly efficient thermoelectric materials raise interesting prospects to further enhance the performances of RTGs for future exploratory missions in the Solar system. Here, we briefly review the knowledge acquired over the last years on several families of thermoelectric materials, the performances of which are close or even higher than those conventionally used in RTGs to date. Issues that remain to be solved are further discussed. [ABSTRACT FROM AUTHOR]

Copyright of Radiology News Journal / Radiološki Vjesnik is the property of Croatian Association of Radiation Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Dragonfly mission to Titan is proposed to use a radioisotope thermoelectric generator to supply electrical and thermal power to the spacecraft during flight and once it arrives at its destination. As no spacecraft continuously powered by an RTG has been flown down through Titan's atmosphere before, the effects of such a generator's radiation field on the surrounding environment are unknown. MCNP (Monte Carlo N-Particle) simulations were run on a simplified model of the generator in its protective hull section in a coarse-grained Titan environment with both neutron and photon transport modelled, the former to determine the degree to which the surface was likely to become activated, and the latter to determine the energy likely to be deposited in a surface covering of tholin-analogue hydrocarbons, and consequently the potential for damage to chemical bonds found therein. Tests on the model also provided data which allowed for a determination of the degree to which the insulation surrounding the generator spacecraft might be activated by stray neutrons, how much heating might be expected in the hull section surrounding the generator and how much attenuation the beam from the spacecraft's pulsed neutron generator is likely to experience due to Titan's thick nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

Alloy systems comprised of silicon with germanium, lead with tellurium, and bismuth with antimony have constituted a majority of thermoelectric applications during the last half-century. These legacy materials are primarily covalently bonded with a maximum ZT near one. Silicon–germanium alloys have provided the thermal to electrical conversion for many of NASA’s radioisotope thermoelectric generator (RTG) configurations and for nearly all of its deep space and outer planetary flights, such as Pioneer I and II, Voyager I and 11, Ulysses, Galileo, and Cassini. The remarkable success of these materials and their respective devices is evidenced by the fact that there has never been a failure of the RTG systems even after over 1 billion cumulative mission-hours. The history of this alloy system as a thermoelectric conversion material spans over six decades and research to further improve its performance continues to this day. Si-Ge alloys have long been a mainstay of thermoelectric research because of a fortuitous combination of a sufficiently high melting temperature, reasonable energy band gap, high solubility for both n- and p-type dopants, and the fact that this alloy system exhibits complete miscibility in the solid state, which enable tuning of both electrical and thermal properties. This article reviews the history of silicon–germanium as a thermoelectric material and its use in NASA’s RTG programs. Since the device technology is also a critical operational consideration, a brief review of some of the unique challenges imposed by the use in an RTG is also discussed.

The NASA enhanced MMRTG (eMMRTG) project seeks to enhance the performance of the Multi-Mission Radioisotope Thermoelectric Generator by exchanging the heritage thermoelectric couple materials and design with that of more efficient skutterudite (SKD)-based thermoelectric (TE) couples. Both at the Jet Propulsion Lab—where the SKD materials were developed—and at Teledyne Energy Systems, Inc.—where the technology is being matured and optimized for fabrication under the Skutterudite Technology Maturation (SKD Tech Mat) Project—many SKD material batches have been produced. A strong correlation has been observed between the TE performance of the materials and the particular lot numbers (same producer and supplier) of various raw materials used to produce the SKD materials. An analysis of the differences between lots, their effects on performance, and the current plan to mitigate the risk posed by these results is discussed. [ABSTRACT FROM AUTHOR]

Exogenous signals induce cells to enter the specialized cell division process of meiosis, which produces haploid gametes from diploid progenitor cells. Once cells initiate the meiotic divisions, it is imperative that they complete meiosis. Inappropriate exit from meiosis and entrance into mitosis can create polyploid cells and can lead to germline tumors. Saccharomyces cerevisiae cells enter meiosis when starved of nutrients but can return to mitosis if provided nutrient-rich medium before a defined commitment point. Once past the meiotic commitment point in prometaphase I, cells stay committed to meiosis even in the presence of a mitosis-inducing signal. Recent research investigated the maintenance of meiotic commitment in budding yeast and found that two checkpoints that do not normally function in meiosis I, the DNA damage checkpoint and the spindle position checkpoint, have crucial functions in maintaining meiotic commitment. Here, we review these findings and discuss how the mitosis-inducing signal of nutrient-rich medium could activate these two checkpoints in meiosis to prevent inappropriate meiotic exit. [ABSTRACT FROM AUTHOR]

Thermoelectric generators (TEGs) rely on a network of individual thermoelectric couples that collectively contribute to the overall power output of the system. As individual couples experience catastrophic failure, complete generator failure occurs when the power output fails to meet the required threshold. A series-parallel wiring arrangement accommodates failure of individual couples without catastrophic failure of the generator, however there exist failure paths that interrupt electrical continuity of the network. In assessing the reliability of a TEG system, the probability of success is measured according to a network's ability to meet both the power level and electrical continuity criteria. A closed-form probabilistic model based on Karr's mathematical formulation (Karr in IEEE Trans Reliab 19(3):116-119, 1970) is used to assess the implications of catastrophic thermoelectric couple failure on the reliability of a complete network. A system-level analysis is performed to evaluate the reliability effects of various network configurations, based on the distribution of a finite number of couples across different numbers of strings. The study explores the tradeoff between redundancy and reliability by assessing the effect of additional couples added to parallel strings and continuing to satisfy acceptable power margins. This model is shown to be a useful tool for designing and understanding the electrical network wiring configurations of TEGs and other power devices. [ABSTRACT FROM AUTHOR]

Robust biological systems are able to adapt to internal and environmental perturbations. This is ensured by a thick crosstalk between metabolism and signal transduction pathways, through which cell cycle progression, cell metabolism and growth are coordinated. Although several reports describe the control of cell signaling on metabolism (mainly through transcriptional regulation and post-translational modifications), much fewer information is available on the role of metabolism in the regulation of signal transduction. Protein-metabolite interactions (PMIs) result in the modification of the protein activity due to a conformational change associated with the binding of a small molecule. An increasing amount of evidences highlight the role of metabolites of the central metabolism in the control of the activity of key signaling proteins in different eukaryotic systems. Here we review the known PMIs between primary metabolites and proteins, through which metabolism affects signal transduction pathways controlled by the conserved kinases Snf1/AMPK, Ras/PKA and TORC1. Interestingly, PMIs influence also the mitochondrial retrograde response (RTG) and calcium signaling, clearly demonstrating that the range of this phenomenon is not limited to signaling pathways related to metabolism.

It has been shown that the following modification of the symmetric (Gilbert) total energy-momentum tensor (EMT) density tμv→tμv−m216πGφ˜μv leads to incorrect results in basic energetic calculations. It is pointed out that some attempts to prove the positive definiteness of the gravitational radiation flux in the RTG are based on the nonconservative energy-momentum tensor. [ABSTRACT FROM AUTHOR]

We consider a model of a scalar field with a nontrivial kinetic part (k-essence) on the background of a flat homogeneous isotropic universe in the framework of the relativistic theory of gravitation and general relativity. Such a scalar field simulates the substance of an ideal fluid and serves as a model of dark energy because it leads to cosmological acceleration at later times. For finding a suitable cosmological scenario, it is more convenient to determine the dependence of the energy density of such a field on the scale factor and only then find the corresponding Lagrangian. Based on the solution of such an inverse problem, we show that in the relativistic theory of gravitation, either any scalar field of this type leads to instabilities, or the compression stage ends at an unacceptably early stage. We note that a consistent model of dark energy in the relativistic theory of gravitation can be a scalar field with a negative potential (ekpyrosis) of Steinhardt-Turok. In general relativity, the k-essence model is viable and can represent both dark energy and dark matter. We consider several specific k-essence models. [ABSTRACT FROM AUTHOR]

Mitochondria perform many essential functions in eukaryotic cells. Being the main producers of ATP and the site of many catabolic and anabolic reactions, they participate in intracellular signaling, proliferation, aging, and formation of reactive oxygen species. Mitochondrial dysfunction is the cause of many diseases and even cell death. The functioning of mitochondria in vivo is impossible without interaction with other cellular compartments. Mitochondrial retrograde signaling is a signaling pathway connecting mitochondria and the nucleus. The major signal transducers in the yeast retrograde response are Rtg1p, Rtg2p, and Rtg3p proteins, as well as four additional negative regulatory factors - Mks1p, Lst8p, and two 14-3-3 proteins (Bmh1/2p). In this review, we analyze current information on the retrograde signaling in yeast that is regarded as a stress or homeostatic response mechanism to changes in various metabolic and biosynthetic activities that occur upon mitochondrial dysfunction. We also discuss relations between retrograde signaling and other signaling pathways in the cell. [ABSTRACT FROM AUTHOR]

Aplikasi Automatic Stacking Crane sebagai alat angkut atau memindahkan container di pelabuhan telah menjadi obyek penelitian pada beberapa tahun terakhir ini. Ketertarikan ini berdasarkan pertimbangan pada upaya untuk mengurangi polusi udara dan suara yang dihasilkan oleh Rubber Tyred Gantry Crane yang selama ini digunakan. Pada penulisan tugas akhir akan dikaji secara teknis dan ekonomis mengenai perancangan dan operasi Automatic Stacking Crane yang telah digunakan oleh PT. Terminal Teluk Lamong PELINDO III. Kajian teknis meliputi penempatan lokasi, komponen, suplai daya dan transmisi, control crane. Kajian ekonomis meliputi biaya operator, biaya operasional, biaya pemeliharaan, biaya pengadaan, biaya pemasukan, biaya pengeluaran, pelunasan dan aliran kas. Hasil yang diperoleh dari penggunaan Automatic Stacking Crane di pelabuhan adalah Automatic Stacking Crane lebih menjamin keselamatan, rendah getaran, suara, dan emisi, lebih baik mudah dalam kontrol dan monitoring dan lebih baik dalam integrasi data, lebih murah dalam biaya operator, operasional, dan pemeliharaan, dan baik untuk investasi jangka panjang, dimana pada tahun ke-16 aliran kas lebih besar 11,767,574,905 dari pada Rubber Tyred Gantry Crane.

Change'4 Lunar Probe will softly land on the farside of the Moon for the first time of all mankind and carry out in-situ and rovering exploration. In this paper, the scientific significance and engineering difficulties of Change'4 are introduced and the probe's general design, including the aspects of landing site selection, relay communication, trajectory design of relay satellite is explained. Besides, four key technologies, namely safe landing strategy on complex terrain, orbit design and control of libration point 2, relay communication on L2, radioisotope thermoelectric generator (RTG) and electric-thermal utilization, as well as how to realize them are also discussed. Finally the prospect of the prominent technological breakthrough of Change'4 is described. [ABSTRACT FROM AUTHOR]

The authors analyze the design of a method for automatized evaluation of parameters in orthopantomographic images capturing pathological tissues developed in human jaw bones. The main problem affecting the applied medical diagnostic procedures consists in low repeatability of the performed evaluation. This condition is caused by two aspects, namely subjective approach of the involved medical specialists and the related exclusion of image processing instruments from the evaluation scheme. The paper contains a description of the utilized database containing images of cystic jaw bones; this description is further complemented with appropriate schematic repre¬sentation. Moreover, the authors present the results of fast automatized segmentation realized via the live-wire method and compare the obtained data with the results provided by other segmentation techniques. The shape parameters and the basic statistical quantities related to the distribution of intensities in the segmented areas are selected. The evaluation results are provided in the final section of the study; the authors correlate these values with the subjective assessment carried out by radiologists. Interestingly, the paper also comprises a discussion presenting the possibility of using selected parameters or their combinations to execute automatic classification of cysts and osteonecrosis. In this context, a comparison of various classifiers is performed, including the Decision Tree, Naive Bayes, Neural Network, k-NN, SVM, and LDA classifica¬tion tools. Within this comparison, the highest degree of accuracy (85% on the average) can be attributed to the Decision Tree, Naive Bayes, and Neural Network classifiers

Copyright of Pediatric Endocrinology, Diabetes & Metabolism is the property of Termedia Publishing House and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The National Aeronautics and Space Administration's Mars Science Laboratory terrestrial rover, Curiosity, has recently completed its first Martian year (687 Earth days) during which it has provided a wealth of information and insight into the red planet's atmosphere and geology. The success of this mission was made possible in part by the reliable electrical power provided by its onboard thermoelectric power source-the multi-mission radioisotope thermoelectric generator (MMRTG). In an effort to increase the output power and efficiency of these generators, a newly designed enhanced MMRTG (eMMRTG) that will utilize the more efficient skutterudite-based thermoelectric materials has been conceptualized and modeled, and is now being developed. A discussion of the motivations, modeling results and key design factors are presented and discussed. [ABSTRACT FROM AUTHOR]