The “alexandrite effect” in gemstones

The term “alexandrite effect” is used in gemology to describe a distinct change of color appearance when a gemstone is switched from daylight to incandescent light. Gemstones that exhibit the alexandrite effect can actually be divided into four categories based upon the value of the calculated absolute hue-angle change of the material under different pairs of illuminants. the alexandrite effect is a non-color-constancy phenomenon. It can be explained by a combination of both chromaticity adaptations to the different light sources, and vision system responses to the spectral distribution of the light emitted by alexandrite effect gemstones when they are illuminated alternatively by the different light sources.     

Remote displacement measurements using a laser diode

A technique for measuring displacements remotely to minimum distances of 8 mm with a resolution of 2 ?m is described. A dynamic interferometer method is employed using a frequency-ramped laser diode. A direct measurement of the period of the resulting beat signal is used to determine the displacement.     

Four-color flow cytometric investigation of terminal deoxynucleotidyl transferase-positive lymphoid precursors in pediatric bone marrow: CD79a expression precedes CD19 in early B-cell ontogeny

Terminal deoxynucleotidyl transferase (TdT)-positive cells in human bone marrow (BM) are a phenotypically inhomogeneous population of precursor cells. In their majority, these TdT+ cells are unambiguously committed to the B lineage, as evidenced by CD19 expression. However, TdT+ precursors that lack CD19 also exist and these may encompass a differentiation potential for the B as well as for other lineages. Because recent data suggested that CD19 expression is not the earliest differentiation event in B-cell ontogeny, we sought to reevaluate TdT+ lymphoid precursors in pediatric BM to define the phenotypic denominator of B-lineage affiliation upstream of CD19. Using four-color flow cytometry, we focused on the assessment of the CD79a antigen, which is highly B-cell specific and which may also be expressed very early in B-cell ontogeny. We found that a majority of TdT+ cells coexpressed CD19 and CD79a in addition to CD10 and CD34, whereas, in all investigated samples, some TdT+ precursors lacked CD19 but expressed CD79a, which suggestively indicates also their B-lineage affiliation. In contrast to the CD19(+) precursors, which were usually CD10(hi) and CD79b+, these CD19(-)CD79a+ putative B-cell precursors preferentially expressed CD10 at low levels and were CD79b+ in only 41%. About 17% of these TdT+CD19(-)CD79a+ precursors also coexpressed CD33 and CD7, but not myeloperoxidase, CD14, or cytoplasmic CD3, which is discussed in the light of cellular activation rather than lineage promiscuity. Our data confirm that the earliest differentiation stages of B cells can be dissected upon expression of the lineage antigens CD79a and CD19 and imply that CD79a is earlier expressed than CD19. This raises the chance to follow the sequential events heralding B-cell commitment in the most immature precursors by correlating phenotypic and genetic differentiation markers.     

Intracerebral hematoma as an acute manifestation of intracranial tumors

Sixteen patients with spontaneous intracerebral haematoma due to intracranial tumours are discussed. The total number of patients with intracranial tumour treated in the period concerned was 594, so the incidence of tumour haemorrhage was 2.7%. In most of the patients we found metastatic neoplasm (n = 6) and glioblastoma (n = 3). All patients were acute admissions. Seven were comatose, seven were somnolent, and two patients were alert. In ten patients the haemorrhage represented the first reliable clinical sign. In six patients a tumour disease was known. Fourteen patients were operated on. Six patients died. Extensive neuro-radiological examination is very important, particularly since 30% of these acute intracerebral haemorrhages occur in patients with benign intracranial tumours.     

Beschichtungen lassen Werkzeuge kalt

Temperature of cutting tools by thin films During the cutting process, cutting tools are exposed to complex mechanical, thermal, dynamic and tribological loads. Especially in the case of dry machining the demands on cutting tools are very high. Dry machining becomes more and more interesting because of tightened up ecolaws and increased costs for the handling of coolants. Due to a renunciation on coolants the cutting tools need to be modified to the process of dry machining. Thereby modern plasma and ion based surface technologies can be used to deposit a thin film adopting the functions of coolants, e.g. cooling and lubricating. In this research project several coating types, e.g. titanium and chromium based coatings, where developed and characterized regarding their mechanical, tribological and thermal properties. For the research, four partners collaborated permuting all steps of surface and coatings design. Materials Science Institute (WW), Aachen University of Technology, performed the development of PVD coatings and the thermophysical characterization by thermal wave analysis. Surface modifications of uncoated and coated tools by ion beam assisted deposition were carried out at Stiftung Institut für Werkstofftechnik (IWT), Bremen. To determine the cutting properties of coated tools, practical tests were performed at Laboratory for Machine Tools and Production Engineering (WZL), Aachen University of Technology.     

Detection of DNA damage in stimulated human lymphocytes after adding cytostatic drugs in vitro. A model to demonstrate individual damage rates

A highly sensitive enzyme-linked immunosorbent assay method has been developed for the determination of tacrolimus in human blood samples. The assay is a modification of the previously published assay with improved sensitivity. Following extraction of tacrolimus with methanol and sulfosalicylic acid, the samples are incubated for 2 h at room temperature on a Nunc Maxisorb plate that has been treated for nonspecific binding by precoating with polyclonal antibody. The analysis of human blood following the standard addition of tacrolimus (0.02-5.0 ng/ml) demonstrated excellent precision and accuracy over a 6-day period. The interday and intraday co-efficients of variation were 6.0-28.9 and 3.9-15.2%, respectively. The limit of quantitation was 0.05 ng/ml. The method was used to quantitate blood concentration of tacrolimus in patients following the administration of tacrolimus ointment.     

0D/2D Heterostructures Vertical Single Electron Transistor

Mixed-dimensional heterostructures formed by the stacking of 2D materials with nanostructures of distinct dimensionality constitute a new class of nanomaterials that offers multifunctionality that goes beyond those of single dimensional systems. An unexplored architecture of single electron transistor (SET) is developed that employs heterostructures made of nanoclusters (0D) grown on a 2D molybdenum disulfide (MoS₂) channel. Combining the large Coulomb energy of the nanoclusters with the electronic capabilities of the 2D layer, the concept of 0D–2D vertical SET is unveiled. The MoS₂ underneath serves both as a charge tunable channel interconnecting the electrode, and as bottom electrode for each v-SET cell. In addition, its atomic thickness makes it thinner than the Debye screening length, providing electric field transparency functionality that allows for an efficient electric back gate control of the nanoclusters charge state. The Coulomb diamond pattern characteristics of SET are reported, with specific doping dependent nonlinear features arising from the 0D/2D geometry that are elucidated by theoretical modeling. These results hold promise for multifunctional single electron device taking advantage of the versatility of the 2D materials library, with as example envisioned spintronics applications while coupling quantum dots to magnetic 2D material, or to ferroelectric layers for neuromorphic devices.