Temperature Coefficients of the Refractive Index for Complex Hydrocarbon Mixtures

Temperature coefficients of the refractive index ( \(\mathrm{d}n/\mathrm{d}T\) ) in the \(25\,^{\circ }\mathrm{C}\) to \(35\,^{\circ }\mathrm{C}\) temperature interval for hydrocarbon mixtures containing as many as 14 compounds were investigated in this work. The measured \(-\mathrm{d}n/\mathrm{d}T\) of the mixtures were compared with calculations based on the values for each compound and their concentrations. Differences of about 1 % between measured and calculated values were observed for all mixtures. The additivity of \(-\mathrm{d}n/\mathrm{d}T\) for these hydrocarbons enables preparation of surrogate fuels that are formulated to have properties like those of specific diesel fuels.     

Modelling and experimental study of multi‐pass wire drawing of hypo‐eutectoid steels

The paper presents the results of extensive experimental research focused on the analysis of deformation conditions in multi‐pass drawing process. The wire rod of medium and high‐carbon steel manufactured with application of controlled cooling rate after hot rolling was chosen as the material to be drawn. Suitability of the wire rod for the multi‐pass drawing process was assessed by means of detailed analysis of mechanical properties of a material before drawing, after each pass as well as of the final product. The drawing process was realised without intermediate heat treatment, assuming maximum possible reduction to be attained. The effect of history of deformation (distribution and number of unit reductions, die geometry) on the mechanical properties of drawn wires was analysed. The force parameters of the drawing process were also evaluated in detail, which allowed for an attempt to determine the optimum drawing conditions. The separate part of work was the upper‐bound process modelling which included calculations of the components of power of deformation as well as the analysis of state of strain by means of strain redundancy factor evaluation. Finally, conclusions were formulated concerning suitability of the investigated wire rod for deep cold working as well as the influence of history of deformation on the product quality.     

Atomic ordering and magnetism in L10 ordered FePd alloys

Intermetallic compounds due to their promising corrosion resistance and high-temperature mechanical strength give hope for their application as high-temperature structural materials. Inter-metallics of L1₀ type structure in recent years in addition have attracted great interest as potential recording media. These alloys are ferromagnetic and display marked mechanical and magnetic anisotropy with the tetragonal c-axis of the ordered domains as the “easy axis” of magnetization High-density magnetic recording may be achieved by a preferential domain orientation with the c-axis perpendicular to the surface, if these materials can be stabilized as low-dimensional magnetic structures. Knowledge of kinetic parameters, that determine alloy stability is essential for alloy design. technical application, and performance of materials. We used FePd as a model system for this class of L1₀-ordered intermetallics and have studied the changes of long-range order during heat treatments in the bulk and in thin films produced by different techniques. Results of X-ray diffraction (XRD). resistivity measurement. Mößbauer spectroscopy, and measurement of magnetization in both geometries are compared.     

Identification of liver cancer-specific aptamers using whole live cells

Liver cancer is the third most deadly cancers in the world. Unfortunately, there is no effective treatment. One of the major problems is that most cancers are diagnosed in the later stage, when surgical resection is not feasible. Thus, accurate early diagnosis would significantly improve the clinical outcome of liver cancer. Currently, there are no effective molecular probes to recognize biomarkers that are specific for liver cancer. The objective of our current study is to identify liver cancer cell-specific molecular probes that could be used for liver cancer recognition and diagnosis. We applied a newly developed cell-SELEX (Systematic Evolution of Ligands by EXponential enrichment) method for the generation of molecular probes for specific recognition of liver cancer cells. The cell-SELEX uses whole live cells as targets to select aptamers (designed DNA/RNA) for cell recognition. In generating aptamers for liver cancer recognition, two liver cell lines were used: a liver cancer cell line BNL 1ME A.7R.1 (MEAR) and a noncancer cell line, BNL CL.2 (BNL). Both cell lines were originally derived from Balb/cJ mice. Through multiple rounds of selection using BNL as a control, we have identified a panel of aptamers that specifically recognize the cancer cell line MEAR with Kd in the nanomolar range. We have also demonstrated that some of the selective aptamers could specifically bind liver cancer cells in a mouse model. There are two major new results (compared with our reported cell-SELEX methodology) in addition to the generation of aptamers specifically for liver cancer. The first one is that our current study demonstrates that cell-based aptamer selection can select specific aptamers for multiple cell lines, even for two cell lines with minor differences (MEAR cell is derived from BNL by chemical inducement); and the second result is that cell-SELEX can be used for adhesive cells and thus open the door for solid tumor selection and investigation. The newly generated cancer-specific aptamers hold great promise as molecular probes for cancer early diagnosis and basic mechanism studies.     

Electron holography for the study of magnetic nanomaterials

Transmission electron microscopes fitted with field-emission guns (to provide coherent electron waves) can be adapted to record the magnetic fields within and surrounding nanoparticles or metal clusters, for example, the lines of force of a nanoferromagnet encapsulated within a multiwalled carbon nanotube. Whereas most chemists are aware that electron microscopy readily identifies crystallographic symmetries and phases, solves structures, and, in conjunction with electron energy-loss spectroscopy, yields valence states and electronic information of materials, relatively few know that it can also provide important quantitative information, with nanometer-scale spatial resolution, pertaining to such materials' magnetic properties. In this Account, with the aid of representative examples embracing solid-state chemistry, geochemistry, and bio-inorganic phenomena, we illustrate how off-axis electron holography affords deep insight into magnetic phenomena on the nanoscale. Specifically, we describe the unprecedented level of information available regarding the magnetic nature of magnetotactic bacteria, magnetic nanoparticle chains and chiral bracelets, and geochemically relevant phenomena involving exsolution (the un-mixing of two mineral phases, as in the magnetite-ulv?spinel system). It is, for example, possible to reveal vortices and multidomain states that have no net magnetization in minute blocks of magnetite. With the current burgeoning interest and activity in nanoscience and nanotechnology, our Account concludes with examples of some existing enigmas that electron holography, especially when augmented by the related technique of electron tomography, might play an important experimental role in resolving, such as the occurrence of ferromagnetism in nanocrystals of silver within carbon tubes and in clusters of alkali metals incarcerated within zeolites.     

Bulk Synthesis and Surface Patterning of Nanoporous Metals and Alloys from Supraspherical Nanoparticle Aggregates

Supraspheres (SS) composed of hundreds to thousands of metal nanoparticles (NPs) and crosslinked by dithiol linkers are assembled into larger structures, which are subsequently converted into nanoporous metals (NMs). Conversion is achieved by heating which removes organic molecules stabilizing the NPs and allows for NP fusion. Heating of SS solutions leads to NMs of overall macroscopic dimensions; localized radiation using collimated electron beam is used to prepare metallized surface micropatterns. Depending on the composition of supraspherical precursors, nanoporous materials composed of up to three metals can be obtained. Strategies for controlling pore size and nanoscale surface roughness of these materials are discussed.     

Locally resolved hysteresis measurement of advanced glass-mat thermoplastic composites

With hysteresis measurement stiffness, creep and damping can be recorded at cyclic loading. Using a laser extensometer a locally resolved hysteresis measurement was formerly developed. It allows to observe several hysteresis-loops simultaneously. Local hysteresis measurement is suitable for fatigue tests of inhomogeneous materials or materials which have inhomogeneous damage process.Locally resolved hysteresis measurement was demonstrated for textile-reinforced advanced glass-mat thermoplastic composites which are interesting for structural components in automotive applications. Cyclic tension tests show stiffness degradation, creep and increasing damping especially for the fracture zones. In cyclic compression loading, the change of the material properties is less pronounced.A component test at a U-profile shows a good agreement between hysteresis measurement and major strain in the fracture zone of the U-profile recorded with digital image correlation.For the interpretation of creep and stiffness degradation at cyclic tension loading, strain oriented considerations were made. It can be shown that for the longitudinal and transversal samples a similar location of the trend-line in a total strain Wöhler-diagram can be found, therefore a total strain dominated failure behavior seems obvious. For further analysis a relative consideration concerning the development of strain amplitude and mid-strain is made. For each single test the ratio between the development of the strain amplitude and the development of the strain middle is calculated. A significant tendency of the above mentioned quotient concerning the stress amplitude can be observed.     

Anomalous Resistance Hysteresis in Oxide ReRAM: Oxygen Evolution and Reincorporation Revealed by In Situ TEM

The control and rational design of redox‐based memristive devices, which are highly attractive candidates for next‐generation nonvolatile memory and logic applications, is complicated by competing and poorly understood switching mechanisms, which can result in two coexisting resistance hystereses that have opposite voltage polarity. These competing processes can be defined as regular and anomalous resistive switching. Despite significant characterization efforts, the complex nanoscale redox processes that drive anomalous resistive switching and their implications for current transport remain poorly understood. Here, lateral and vertical mapping of O vacancy concentrations is used during the operation of such devices in situ in an aberration corrected transmission electron microscope to explain the anomalous switching mechanism. It is found that an increase (decrease) in the overall O vacancy concentration within the device after positive (negative) biasing of the Schottky‐type electrode is associated with the electrocatalytic release and reincorporation of oxygen at the electrode/oxide interface and is responsible for the resistance change. This fundamental insight presents a novel perspective on resistive switching processes and opens up new technological opportunities for the implementation of memristive devices, as anomalous switching can now be suppressed selectively or used deliberately to achieve the desirable so‐called deep Reset.