A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

A prototype electric power management and thruster control system for a 30 cm ion thruster is described. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The power management and control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete power management and control system measures 45.7 cm (18 in.) x 15.2 cm (6 in.) x 114.8 cm (45.2 in.) and weighs 36.2 kg (79.7 lb). At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned

Synthetic Nanoelectronic Probes for Biological Cells and Tissues

Research at the interface between nanoscience and biology could yield breakthroughs in fundamental science and lead to revolutionary technologies. In this review, we focus on the interfaces between nanoelectronics and biology. First, we discuss nanoscale field effect transistors (nanoFETs) as probes to study cellular systems; specifically, we describe the development of nanoFETs that are comparable in size to biological nanostructures involved in communication through synthesized nanowires. Second, we review current progress in multiplexed extracellular sensing using planar nanoFET arrays. Third, we describe the designs and implementation of three distinct nanoFETs used to perform the first intracellular electrical recording from single cells. Fourth, we present recent progress in merging electronic and biological systems at the three-dimensional tissue level by use of macro-porous nanoelectronic scaffolds. Finally, we discuss future developments in this research area, unique challenges and opportunities, and the tremendous impact these nanoFET-based technologies might have on biological and medical sciences.Chemistry and Chemical BiologyEngineering and Applied Science

Design and fabrication of silicon nanowires towards efficient solar cells

The recent rise of semiconductor nanowires opens new opportunities for realizing high efficiency photovoltaic devices at low cost due to the unique one-dimensional structure with remarkable electrical and optical properties. Particularly, silicon nanowires (SiNWs), as one of the most earth-abundant materials, have been investigated worldwide to develop cost-effective solar cells. Great efforts have been devoted to fabricating ordered/disordered SiNWs using cost-effective approaches and achieving optimized structural parameters, such as array periodicity, nanowire morphology, length and diameter. Systematic theoretical investigations along with experimental studies on optical and electrical properties of SiNWs have been carried out. These efforts have led to obtaining remarkable improvement of the power conversion efficiency of SiNW solar cells from 10% in the last few years. However, till now, the power conversion efficiency of these SiNW solar cells is far from satisfactory for any commercial applications compared with the traditional bulk silicon solar cells. Further development of SiNW solar cells requires better understanding of the optical and electrical properties of the nanowire solar cells. Improvement in fabrication of high quality nanowires in a controlled fashion also plays a significant role in nanowire solar cell design and fabrication. To guide future development of SiNW solar cells, the recent work on SiNWs is reviewed. Following that, various techniques aiming to achieve high quality nanowires at low cost are introduced. Both bottom-up and top-down techniques are discussed. Then, electrical properties and various types of solar cells based on SiNWs are discussed. Finally challenges and prospects of SiNW solar cells are presented

Клинические применения биосенсоров на основе полевых транзисторов с углеродными нанотрубками или нанопроводами

В цій статті ми описуємо останні досягнення в стрімко розвиваній області детектування аналітів з використанням польових транзисторів (ПТ) на основі вуглецевих нанотрубок і нанопроводів. У цій статті відображено поведінку та переваги одновимірних наноматеріалів для використання в біосенсорах. Поміж одновимірних нанометрових матеріалів вуглецеві нанотрубки і нанопроводи пропонують унікальні електронні та механічні властивості, які роблять їх надзвичайно привабливими для задач біодетектування. Проаналізовано структури і принципи роботи ПТ-біосенсорів на основі вуглецевих нанотрубок / нанопроводів. Польові транзистори на основі вуглецевих нанотрубок / кремнієвих нанопроводів останнім часом привертають до себе величезну увагу як перспективні інструменти для проектування біосенсорів, через їх біосумісність, сумісності за розміром, ультрачутливість, селективність, а також можливості без маркерного виявлення в режимі реального часу. Крім того, також проаналізовано механізми взаємодії між елементами трансдьюсера ПТ-біосенсора (вуглецевими нанотрубками або нанопроводами) та біооб'єктами. На закінчення, в цьому огляді основна увага приділяється застосуванню біосенсорів на основі польових транзисторів для вимірювання різних аналітів. Показано взаємодію білків, реакцію антитіло-антиген, включаючи реакцію виявлення простатспецифічного антигену, ДНК-гібридизацію і ферментативні реакції за участі глюкози.In this paper we describe recent advances in the rapidly developing area of analyte detection using field-effect transistors (FETs)based on carbon nanotubes or nanowires. In this article behavior and advantages of onedimensional nanomaterials for biosensing application is depicted. Among onedimensional nanometer-scale materials, carbon nanotubes and nanowires offer unique electronic and mechanical properties that make them extremely attractive for the task of biosensing. The structures and work principles of FETbiosensors based on carbon nanotubes/nanowires is discussed. Carbon nanotubes/silicon nanowire field-effect transistors have recently attracted great attention as promising tools in biosensor design because of their biocompatibility, size compatibility, ultrasensitivity, selectivity and label-free and real-time detection capabilities. In addition, interaction mechanisms between transducer elements of FET-biosensor (carbon nanotubes or nanowires) and target entities is also reviewed. Finally, applications of FET-type biosensors for measurement of different analytes is highlighted in this review. Proteins interaction, antibody–antigen reactions including prostate-specific antigen detection, DNA hybridization and enzymatic reactions involving glucose is shown.В этой статье мы описываем последние достижения в стремительно развивающейся области детектирования аналитов с использованием полевых транзисторов (ПТ на основе углеродных нанотрубок и нанопроводов. В статье описаны поведение и преимущества одномерных наноматериалов для использовании в биодатчиках. Среди одномерных нанометровых материалов углеродные нанотрубки и нанопроводы предлагают уникальные электронные и механические свойства, которые делают их чрезвычайно привлекательными для задач биодетектирования.Проанализированы структуры и принципы работы ПТ-биосенсоров на основе углеродных нанотрубок/нанопроводов. Полевые транзисторы на основе углеродных нанотрубок/кремниевых нанопроводов в последнее время привлекают к себе большое внимание как перспективные инструменты для проектирования биосенсоров из-за их биосовместимости, совместимости по размеру, ультрачувствительности, избирательности, а также возможностям без маркерного обнаружения в режиме реального времени. Кроме того, также проанализированы механизмы взаимодействия между элементами трансдьюсера ПТ-биосенсора (углеродными нанотрубками или нанопроводами) и объектами. В заключение,этом обзоре основное внимание отводиться применению биосенсоров на основе полевых транзисторов для измерения различных аналитов. Показаны реакции взаимодействия белков, реакция антитело-антиген, включая реакцию обнаружения простат-специфического антигена, ДНК-гибридизацию и ферментативные реакции с участием глюкозы

Delayed neutron assay to test sorbers for uranium-from-seawater applications

Includes bibliographical references (pages 106-107)Final Report of the Uranium from Seawater Project ; FY 1981U.S. Dept. of Energy 80-499-

Linker Flexibility Facilitates Module Exchange in Fungal Hybrid PKS-NRPS Engineering

Polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) each give rise to a vast array of complex bioactive molecules with further complexity added by the existence of natural PKS-NRPS fusions. Rational genetic engineering for the production of natural product derivatives is desirable for the purpose of incorporating new functionalities into pre-existing molecules, or for optimization of known bioactivities. We sought to expand the range of natural product diversity by combining modules of PKS-NRPS hybrids from different hosts, hereby producing novel synthetic natural products. We succeeded in the construction of a functional cross-species chimeric PKS-NRPS expressed in Aspergillus nidulans. Module swapping of the two PKS-NRPS natural hybrids CcsA from Aspergillus clavatus involved in the biosynthesis of cytochalasin E and related Syn2 from rice plant pathogen Magnaporthe oryzae lead to production of novel hybrid products, demonstrating that the rational re-design of these fungal natural product enzymes is feasible. We also report the structure of four novel pseudo pre-cytochalasin intermediates, niduclavin and niduporthin along with the chimeric compounds niduchimaeralin A and B, all indicating that PKS-NRPS activity alone is insufficient for proper assembly of the cytochalasin core structure. Future success in the field of biocombinatorial synthesis of hybrid polyketide-nonribosomal peptides relies on the understanding of the fundamental mechanisms of inter-modular polyketide chain transfer. Therefore, we expressed several PKS-NRPS linker-modified variants. Intriguingly, the linker anatomy is less complex than expected, as these variants displayed great tolerance with regards to content and length, showing a hitherto unreported flexibility in PKS-NRPS hybrids, with great potential for synthetic biology-driven biocombinatorial chemistry

Knockdown of plakophilin 2 downregulates MIR-184 through CpG hypermethylation and suppression of the E2F1 pathway and leads to enhanced adipogenesis in vitro

Rationale: PKP2, encoding plakophilin 2 (PKP2), is the most common causal gene for arrhythmogenic cardiomyopathy. Objective: To characterize miRNA expression profile in PKP2-deficient cells. Methods and results: Control and PKP2-knockdown HL-1 (HL-1(Pkp2-shRNA)) cells were screened for 750 miRNAs using low-density microfluidic panels. Fifty-nine miRNAs were differentially expressed. MiR-184 was the most downregulated miRNA. Expression of miR-184 in the heart and cardiac myocyte was developmentally downregulated and was low in mature myocytes. MicroRNA-184 was predominantly expressed in cardiac mesenchymal progenitor cells. Knockdown of Pkp2 in cardiac mesenchymal progenitor cells also reduced miR-184 levels. Expression of miR-184 was transcriptionally regulated by the E2F1 pathway, which was suppressed in PKP2-deficient cells. Activation of E2F1, on overexpression of its activator CCND1 (cyclin D1) or knockdown of its inhibitor retinoblastoma 1, partially rescued miR-184 levels. In addition, DNA methyltransferase-1 was recruited to the promoter region of miR-184, and the CpG sites at the upstream region of miR-184 were hypermethylated. Treatment with 5-aza-2'-deoxycytidine, a demethylation agent, and knockdown of DNA methyltransferase-1 partially rescued miR-184 level. Pathway analysis of paired miR-184:mRNA targets identified cell proliferation, differentiation, and death as the main affected biological processes. Knockdown of miR-184 in HL-1 cells and mesenchymal progenitor cells induced and, conversely, its overexpression attenuated adipogenesis. Conclusions: PKP2 deficiency leads to suppression of the E2F1 pathway and hypermethylation of the CpG sites at miR-184 promoter, resulting in downregulation of miR-184 levels. Suppression of miR-184 enhances and its activation attenuates adipogenesis in vitro. Thus, miR-184 contributes to the pathogenesis of adipogenesis in PKP2-deficient cells