Active Self‐Assembly of Train‐Shaped DNA Nanostructures via Catalytic Hairpin Assembly Reactions

Biomolecular self‐assembly is a powerful approach for fabricating supramolecular architectures. Over the past decade, a myriad of biomolecular assemblies, such as self‐assembly proteins, lipids, and DNA nanostructures, have been used in a wide range of applications, from nano‐optics to nanoelectronics and drug delivery. The method of controlling when and where the self‐assembly starts is essential for assembly dynamics and functionalization. Here, train‐shaped DNA nanostructures are actively self‐assembled using DNA tiles as artificial “carriages,” hairpin structures as “couplers,” and initiators of catalytic hairpin assembly (CHA) reactions as “wrenches.” The initiator wrench can selectively open the hairpin couplers to couple the DNA tile carriages with high product yield. As such, DNA nanotrains are actively prepared with two, three, four, or more carriages. Furthermore, by flexibly modifying the carriages with “biotin seats” (biotin‐modified DNA tiles), streptavidin “passengers” are precisely arranged in corresponding seats. The applications of the CHA‐triggered self‐assembly mechanism are also extended for assembling the large DNA origami dimer. With the creation of 1D architectures established, it is thought that this CHA‐triggered self‐assembly mechanism may provide a new element of control for complex autonomous assemblies from a variety of starting materials with specific sites and times.     

Wolfgang Gaede ‐ Wegbereiter der Vakuumtechnik

The inventions of Wolfgang Gaede were the beginning of the extensive industrial application of vacuum technology: the 1905 invented high vacuum mercury pump simplified the production of electric bulbs. From this time Gaede joined the company E. Leybold's Nachfolger research & development activities for 40years. Three of his inventions, the diffusion pump, the (turbo‐) molecular pump and the principle of “gas ballast” are worldwide in use even today. The most important stations of Gaede's biography are reported.     

Vakuummikro‐ und Vakuumnanoelektronik mit Feldemission

Vacuum microelectronics and nanoelectronics with field emission — features of breakdown voltage in vacuum gaps lower than 10 μm Further miniaturization in vacuum electronics will be possible only with field‐emitter cathodes. However in microscale vacuum gaps in the range 10 μm field emission is a dominant process in gas breakdown process, leading to signif icant deviations from the traditional Paschen's Law. At first a significant reduction of breakdown voltage is observed. The high surface‐to‐volume ratio in microscale dimensions 3 μm and in interactions with gas desorption, outgassing and gas ionization during electron field‐emission give a ignition and stabilization of micro plasmas (glow discharges) or/and micro arcs, which exist largely independent of surrounding vacuum, atmospheric or over pressure. In this range the Paschen's Law is invalid. This is an interesting approach which opens up new dimensions for basic research, field emission‐driven micro plasmas and for novel fieldemitter applications in vacuum electronics and plasma technology.     

Safeguarding and retrofitting works at the UNESCO World Heritage Site Takht‐e Soleyman,Iran

This article reports on the works safeguard in 2016 to secure the UNESCO World Heritage Site at Takht‐e Soleyman in the province of West Azerbaijan in the northwest of Iran. The site includes a fire temple and dates back to the sixth century AD. The complex was transformed by the Ilkhanids in the 13th century with extensive repair and building measures. From the 15th century, the complex was abandoned and decayed. In the 1970s, the north wall of the Western Eivan was first secured with steel scaffolding. The Chair of Structural design at the TU Dresden undertook works in 2016 to stabilise the Western Eivan in collaboration with the Iranian cultural heritage organisation (ICHHTO) and with financial support from the cultural maintenance programme of the Federal Foreign Office of Germany. The preliminary investigations until now and the work to the structure planned for 2018 are described below.     

The Manufacture and Use of Albumen Paper

Albumen paper was the most widely used photographic printing material in the nineteenth century. It was a pure silver chloride printing-out paper, manually coated sheet by sheet in factories and usually sensitized by the user at the time of use by floating on a silver nitrate solution. Processing involved gold toning and fixing with sodium thiosulphate.

The centre of world manufacture was in Dresden, Germany, where two large companies dominated the industry. Raw stock was supplied from only two paper mills which held a virtual world monopoly. Presensitized and roll-coated gelatin and collodion printing-out papers finally captured the market from albumen paper in the early 1890’s. Albumen paper enjoyed a revival around World War I when “matte-albumen” papers, made with a mixture of starch and albumen, were briefly popular. The last commercial production of albumen paper is believed to have been in 1929.     

ADI Lost‐Foam: Synergy of Process and Material

A consortium of SME and RTD partners from Germany, Poland, Italy and Finland was established in the ambit of the fifth European framework programme for the development of a process that combined Lost‐Foam with a high performance ADI – Austempered Ductile Iron Cast Iron. In the Lost‐Foam process foam patterns are used as models for complex and near net shape castings. These models are coated with a special refractory paint. The models are surrounded by unbonded sand and then filled with liquid metal. As the alloyed ductile iron melt decomposes the foam, the coating material is of great importance for the effective extraction of the foam decomposition products. By means of a posterior special heat treatment it is possible to achieve tensile strengths ranging from 800 to 1600 MPa with elongations ranging from 1 % to 12 %. The main achievements of the performed investigations were the development of the alloy and respective heat treatment parameters for the base ductile iron as well as a suitable coating material. Moreover, these investigations showed that it is possible to produce ADI castings capable of achieving the same mechanical properties as forged steel crankshafts with a significant weight reduction. Additionally, the production of such castings through the Lost‐Foam process have a yield of more than 87 % as opposed to the typical yield of the traditional green sand process which can reach 55 %.     

Micrometer‐ and Nanometer‐Sized Organic Single‐Crystalline Transistors

The use of micrometer and nanometer‐sized organic single crystals to fabricate devices can retain all the advantages of single crystals, avoid the difficulties of growing large crystals, and provide a way to characterize organic semiconductors more efficiently. Moreover, the effective use of such “small” crystals will be beneficial to nanoelectronics. Here we review the recent progress of organic single‐crystalline transistors based on micro‐/nanometer‐sized structures, namely fabrication methods and related technical issues, device properties, and current challenges.     

Black‐Phosphorus‐Based Orientation‐Induced Diodes

Despite many decades of research of diodes, which are fundamental components of electronic and photoelectronic devices with p–n or Schottky junctions using bulk or 2D materials, stereotyped architectures and complex technological processing (doping and multiple material operations) have limited future development. Here, a novel rectification device, an orientation‐induced diode, assembled using only few‐layered black phosphorus (BP) is investigated. The key to its realization is to utilize the remarkable anisotropy of BP in low dimensions and change the charge‐transport conditions abruptly along the different crystal orientations. Rectification ratios of 6.8, 22, and 115 can be achieved in cruciform BP, cross‐stacked BP junctions, and BP junctions stacked with vertical orientations, respectively. The underlying physical processes and mechanisms can be explained using “orientation barrier” band theory. The theoretical results are experimentally confirmed using localized scanning photocurrent imaging. These orientation‐induced optoelectronic devices open possibilities for 2D anisotropic materials with a new degree of freedom to improve modulation in diodes.     

Erste vertikale In‐line Fertigungsanlage für OLEDs. New vertical in‐line solution for OLED production

The company Applied Films recently introduced a newly developed vertical In‐Line process for the production of Organic Light Emitting Diodes (OLEDs). The solution is caracterized by high throughput rates and efficient material utilization. Features which make the system appropriate for mass production. It is presently tested at the Dresden based Fraunhofer Institute for Photonic Microsystems.     

Demountable prototype house – from facade to water tap

In connection with climate development, our buildings, both existing and newbuild, have to be intensively investigated regarding their energy balance and use of resources. An energy‐efficient dry building system capable of being recycled is important for new building today. This is the starting point for the project ReDeMaM (recyclable – demountable – highly energy‐efficient – massive – prototype house), to investigate whether appropriate systems are already available on the market and to what extent these are compatible with each other. The end result should be a prototype house, which includes all necessary elements including finishings with the objective of being capable of being dismantled, reused and recycled. The research project is supported by the research initiative Zukunft Bau (future building) and is currently underway at the Chair of Structural Design at the TU Dresden.     

“Dual Lock‐and‐Key”‐Controlled Nanoprobes for Ultrahigh Specific Fluorescence Imaging in the Second Near‐Infrared Window

Fluorescence imaging in the second near‐infrared window (NIR‐II) is a new technique that permits visualization of deep anatomical features with unprecedented spatial resolution. Although attractive, effectively suppressing the interference signal of the background is still an enormous challenge for obtaining target‐specific NIR‐II imaging in the complex and dynamic physiological environment. Herein, dual‐pathological‐parameter cooperatively activatable NIR‐II fluorescence nanoprobes (HISSNPs) are developed whereby hyaluronic acid chains and disulfide bonds act as the “double locks” to lock the fluorescence‐quenched aggregation state of the NIR‐II fluorescence dyes for performing ultrahigh specific imaging of tumors in vivo. The fluorescence can be lit up only when the “double locks” are opened by reacting with the “dual smart keys” (overexpressed hyaluronidase and thiols in tumor) simultaneously. In vivo NIR‐II imaging shows that they reduce nonspecific activitation and achieve ultralow background fluorescence, which is 10.6‐fold lower than single‐parameter activatable probes (HINPs) in the liver at 15 h postinjection. Consequently, these “dual lock‐and‐key”‐controlled HISSNPs exhibit fivefold higher tumor‐to‐normal tissue ratio than “single lock‐and‐key”‐controlled HINPs at 24 h postinjection, attractively realizing ultrahigh specificity of tumor imaging. This is thought to be the first attempt at implementing ultralow background interference with the participation of multiple pathological parameters in NIR‐II fluorescence imaging.     

Laserstrahlbasiertes Reparaturlöten in der Elektronik‐Produktion

Laser based rework in electronic production A production of electronic boards with a zero defect‐rate is not attainable still in today’s electronic manufacturing. Boards with defect solder joints or defect components will often be recirculated to a manual rework process, in which the quality and the economical load are depending on quality of personal and system. This paper presents possibilities for the automation of assembly and soldering processes using a diode laser system. Main facts are the advantages of laser systems for rework processes, possibilities of system technical realization and industrial feasibility. In process technical point of view influences of quality after rework processes will be discussed.     

Polymer–Fullerene Bulk‐Heterojunction Solar Cells

Solution‐processed bulk heterojunction organic photovoltaic (OPV) devices have gained serious attention during the last few years and are established as one of the leading next generation photovoltaic technologies for low cost power production. This article reviews the OPV development highlights of the last two decades, and summarizes the key milestones that have brought the technology to today’s efficiency performance of over 7%. An outlook is presented on what will be required to drive this young photovoltaic technology towards the next major milestone, a 10% power conversion efficiency, considered by many to represent the efficiency at which OPV can be adopted in wide‐spread applications. With first products already entering the market, sufficient lifetime for the intended application becomes more and more critical, and the status of OPV stability as well as the current understanding of degradation mechanisms will be reviewed in the second part of this article.     

„Ideale“ Lötverbindung und „optimale“ Lötverbindung

If due to the market analysis a company makes the decision for the production of a new product by application of soldering and special the soldering with temporarily liquid solder, this one is then made specifically after that the company specific construction and production preparation. Either the decision for soldering is technically and/or economically well‐founded or she is even unavoidable by so‐called mixed material connections in the assemblies. This hybrid design finds application increasing today. In the contribution on hand the analysis and assessment of the soldering theory and practice is carried out under the point of view of the possible production of “ideal soldered connections” and “optimal soldered connections”.     

Dünnschicht‐Photovoltaik in Deutschland

Prospects for thin‐film PV in Germany Due to the German Energy Supply Act the photovoltaics market will continue to grow in Germany. The predicted fall in costs will require companies to implement a continuous improvement in efficiency while at the same time reducing process costs. This must be achieved by a constant increase in research performance. The aim here is the fastest possible reduction in power generation costs into or below the range of costs which can be reached with conventional energy carriers. In this respect the German industrial and research landscape is very well set up. Industry aspires to covering 12% of power requirements throughout Europe in by 2020 by means of photovoltaics [5]. At the present time in Germany less than 1% of power requirements is covered. For Germany the prospects are very good for taking up a leading role globally in thin‐film photovoltaics alongside the established crystalline silicon technology.     

Necessary changes in the residential building sector to achieve the climate protection aims for 2030/2050

The aims of German energy and climate policy are ambitious: by 2050, emissions of greenhouse gases should be reduced by at least 80 %, ideally by 95 % compared to 1990. In addition, there are the decisions of the Paris Climate Accord, which intends to limit global warming to considerably less than 2°, better to 1.5°. The building sector as is known plays an important role in the energy transition. The transformation of the building industry and its thermal consumption is of decisive importance for the energy transition as a whole. A study recently commissioned by the alliance for building energy efficiency (geea), the German energy agency (dena) and further industry associations with the title ”Scenarios for a market‐based climate and resources policy 2050 in the building sector“ [1] shows clearly that the ”business as usual“ strategy will not suffice in order to even near the climate protection aims in the building sector. The scientific processing was undertaken by the ewi Energy Research & Scenarios, the institute for building services Dresden (ITG Dresden) and the research institute for thermal insulation (FIW Munich). The scope of this article only deals with the share of residential buildings.     

State of the Art of Single‐Walled Carbon Nanotube Synthesis on Surfaces

Single‐walled carbon nanotubes (SWNTs) directly synthesized on surfaces are promising building blocks for nanoelectronics. The structures and the arrangement of the SWNTs on surfaces determine the quality and density of the fabricated nanoelectronics, implying the importance of structure controlled growth of SWNTs on surfaces. This review summarizes the recent research status in controlling the orientation, length, density, diameter, metallicity, and chirality of SWNTs directly synthesized on surfaces by chemical vapor deposition, together with a session presenting the characterization method of the chirality of SWNTs. Finally, the remaining major challenges are discussed and future research directions are proposed.     

Dry laying of masonry to build demountable,highly energy‐efficient prototype houses – First findings from a currently running research project

In recent decades, energy efficiency has been the priority for masonry buildings in order to keep up with ever more stringent requirements. For the evaluation of the sustainability of building solutions, however, the embodied energy to produce a building and finally to dispose of it at the end of its lifecycle are also important. The energy used for the disposal of a building and the processing of the residues are also important for the overall energy balance since the handling of natural resources is increasingly the centre point of thought and action. A research team at the Chair of Structural Design of TU Dresden has thus been working since 2012 on demountable solutions in masonry, which can be dismantled at the end of a building lifetime and sorted for recycling, which fully complies with the requirement for the reduction of rubbish and waste products. The high precision of block production today permits us to omit the levelling effect of mortar and to build dry buildings in the future, i.e. to do without the bonding principle. The associated strength reductions can be suffered without problems. The appropriate basics of such a dry building method have been researched in a collaboration between the ILEK in Stuttgart and the Xella Technologie‐ und Forschungsgesellschaft mbH in Emstal. In this research project with the abbreviation ”REMOMAB“, the basics of an energy‐efficient dry building method suitable for recycling were collected and made available for practical application. In a follow‐up project, these basics are being implemented and tested on an experimental building. Cost aspects are also to be taken into account and if possible, construction solutions available on the market will be used – modified if necessary. Another aim is for the first time to dismantle such a building and to rebuild it at another location. This is intended to demonstrate that a reuse is possible after dismantling and such a building method can react to changing demands in the housing market.