Fluorescent color centers in laser ablated 4H-SiC nanoparticles.

Nanostructured and bulk silicon carbide (SiC) has recently emerged as a novel platform for quantum nanophotonics due to its harboring of paramagnetic color centers, having immediate applications as a single photon source and spin optical probes. Here, using ultra-short pulsed laser ablation, we fabricated from electron irradiated bulk 4H-SiC, 40-50 nm diameter SiC nanoparticles, fluorescent at 850-950 nm. This photoluminescence is attributed to the silicon vacancy color centers. We demonstrate that the original silicon vacancy color centers from the target sample were retained in the final nanoparticles solution, exhibiting excellent colloidal stability in water over several months. Our work is relevant for quantum nanophotonics, magnetic sensing, and biomedical imaging applications.

A review on single photon sources in silicon carbide.

This paper summarizes key findings in single-photon generation from deep level defects in silicon carbide (SiC) and highlights the significance of these individually addressable centers for emerging quantum applications. Single photon emission from various defect centers in both bulk and nanostructured SiC are discussed as well as their formation and possible integration into optical and electrical devices. The related measurement protocols, the building blocks of quantum communication and computation network architectures in solid state systems, are also summarized. This includes experimental methodologies developed for spin control of different paramagnetic defects, including the measurement of spin coherence times. Well established doping, and micro- and nanofabrication procedures for SiC may allow the quantum properties of paramagnetic defects to be electrically and mechanically controlled efficiently. The integration of single defects into SiC devices is crucial for applications in quantum technologies and we will review progress in this direction.

Diamond encapsulated photovoltaics for transdermal power delivery.

A safe, compact and robust means of wireless energy transfer across the skin barrier is a key requirement for implantable electronic devices. One possible approach is photovoltaic (PV) energy delivery using optical illumination at near infrared (NIR) wavelengths, to which the skin is highly transparent. In the work presented here, a subcutaneously implantable silicon PV cell, operated in conjunction with an external NIR laser diode, is developed as a power delivery system. The biocompatibility and long-term biostability of the implantable PV is ensured through the use of an hermetic container, comprising a transparent diamond capsule and platinum wire feedthroughs. A wavelength of 980 nm is identified as the optimum operating point based on the PV cell's external quantum efficiency, the skin's transmission spectrum, and the wavelength dependent safe exposure limit of the skin. In bench-top experiments using an external illumination intensity of 0.7 W/cm(2), a peak output power of 2.7 mW is delivered to the implant with an active PV cell dimension of 1.5 × 1.5 × 0.06 mm(3). This corresponds to a volumetric power output density of ~20 mW/mm(3), significantly higher than power densities achievable using inductively coupled coil-based approaches used in other medical implant systems. This approach paves the way for further ministration of bionic implants.

Single-photon emitting diode in silicon carbide.

Electrically driven single-photon emitting devices have immediate applications in quantum cryptography, quantum computation and single-photon metrology. Mature device fabrication protocols and the recent observations of single defect systems with quantum functionalities make silicon carbide an ideal material to build such devices. Here, we demonstrate the fabrication of bright single-photon emitting diodes. The electrically driven emitters display fully polarized output, superior photon statistics (with a count rate of >300 kHz) and stability in both continuous and pulsed modes, all at room temperature. The atomic origin of the single-photon source is proposed. These results provide a foundation for the large scale integration of single-photon sources into a broad range of applications, such as quantum cryptography or linear optics quantum computing.

Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids.

Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 10(15) molecules per cm(2) down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers.

Pre-winter lipid stores in young-of-year Atlantic salmon along a north-south gradient.

The pre-winter lipid stores of young-of-the-year (YOY, age 0 year) Atlantic salmon Salmo salar were analysed along a north-south gradient from c. 71 to 58 degrees N, with winter conditions ranging from >200 days of ice cover to no ice. The rivers sampled in Northern Norway represent some of the most northerly S. salar rivers. There was an increase in lipid content with increasing latitude, and mean lipid content (size adjusted to common mass) for YOY in northern rivers were almost three times higher: 0.035 g compared to 0.013 g in southern rivers. The relationship was not sensitive to variation in sampling time or variation in YOY body size. The lipid stores, however, varied markedly between rivers and also between neighbouring rivers, indicating different strategies or opportunities for pre-winter lipid storage both at latitudinal and local scales.

[Multiple endocrine adenopathy type IIb. 15-years' observation of a case]. / Multiple endokrine Adenopathie Typ IIb. Fallbeobachtung über 15 Jahre.

MEA IIb is a combination of C-cell carcinoma of the thyroid, phaeochromocytoma, multiple neuromas and a marfanoid habitus. A hyperplasia of the parathyroid cannot be found in most of the patients with this variant of Sipple's syndrome. In a 30-year-old woman, a MEA IIb could be observed over 15 years. Although primary surgery of the C-cell-carcinoma was insufficient, metastases were not found following two more surgical interventions in spite of elevated serum calcitonin. A phaeochromocytoma was not found, too. The reported case is compared with the literature.

[Neurofibroma of the small bowel in Recklinghausen's disease as a rare cause of chronic intestinal bleeding (author's transl)]. / Dünndarm-Neurofibrom bei Morbus Recklinghausen als Ursache rezidivierender gastrointestinaler Blutungen.

A case report is given of a 66 year old woman with Recklinghausen's disease, suffering from chronic gastrointestinal bleeding as a rare complication of enteric neurofibromatosis. Localization could be established only by angiography. After resection of the tumor with an ulceration at its tip hemorrhage stopped. The incidence of gastrointestinal neurofibromatosis, as well as its symptoms, diagnosis and treatment are discussed.

[Immunsuppressive factors in sera and synovial fluids of patients with rheumatoid arthritis (author's transl)]. / Immunsuppressive Faktoren in Seren und Synovialflüssigkeiten von Patienten mit chronischer Polyarthritis.

Serum inhibitory factors (SIF) have been demonstrated in several infectious diseases and autoimmune disorders. Most likely, they are caused by an immune reaction, and their persistence indicates a chronic course. Sera and synovial fluids of 31 patients with rheumatoid arthritis and of 33 patients with arthrosis were therefore studied, in order to determine whether immunosuppressive factors exist only in inflammatory diseases and whether their titers correlate with the activity of the disease. PHA-induced stimulation of normal peripheral blood lymphocytes, measured as 3H thymidine uptake, in the presence of patients' serum, was related to lymphocyte stimulation observed in the presence of control sera. Using the MIF-agarose assay, the effect of sera and synovial fluids on the tuberculin-induced migration inhibition was also studied. Sera of 27 of 31 patients with rheumatoid arthritis inhibited mitogen-induced normal lymphocyte thymidine uptake and abolsihed migration inhibition, probably by blocking MIF-production. High titers appeared to predict an unfavourable course. In contrast, sera of all 33 patients with degenerative joint disease failed to exert these effects. Synovial fluids of all patients, irrespective of the nature of the underlying joint disease, did not affect lymphocyte stimulation or leukocyte migration. Other factors, such as immune complexes, cytotoxic antibodies, or drug metabolites could be excluded as potential causes of the observed effects exerted by rheumatoid arthritis sera. These results indicate that the presence of serum factors inhibiting PHA-induced lymphocyte stimulation and leukocyte migration inhibition, respectively, may be used as a diagnostic tool in the differential diagnosis of rheumatoid arthritis.