Heraeus (United States)

Bone cement is commonly utilized in a variety of orthopaedic procedures and contains methylmethacrylate (MMA) monomer. MMA is a colorless, clear, flammable liquid of intense odor. Its vapor concentration in the immediate breathing zone can vary considerably in the operative setting and, in higher concentrations, can become an occupational health hazard. Therefore, reducing MMA vapor is desirable. The aim of this study was to compare the MMA vapor levels emitted during mixing among 5 commercially available cement-mixing systems across 2 operative settings: an operating room (OR) with conventional ventilation (CV) and an OR with laminar airflow (LAF). A prospective, in vitro study was conducted at a single hospital in an OR with LAF and in an OR with CV. MMA vapor release during the cement preparation of a SAWBONES femoral canal was measured with use of a calibrated MiniRAE 3000. A total of 5 different vacuum cement-mixing systems were utilized to mix the same cement type according to the manufacturer instructions of each system. MMA vapor concentrations were measured during 5 phases of mixing, and each mixing system was randomly utilized 10 times in each OR. When comparing the MMA concentration levels of each system between the 2 settings, emissions remained generally higher in the CV setting for every system and in nearly every phase. Among the 5 systems analyzed, System #5, the only entirely closed system, had the lowest overall emissions for each of the 5 phases in the CV setting. This study demonstrated that an operative environment with LAF is conducive to clearing the fumes of MMA during mixing as well as limiting the amount of time that residual fumes linger after mixing. Additionally, the entirely closed cement-mixing system was the most effective in minimizing fume levels within the CV setting. Utilizing this closed system, especially in an OR with CV, may reduce exposure to MMA fumes from bone cement, potentially creating a more favorable working environment. This study provides evidence that a closed cement-mixing system utilized under vacuum in both an OR with CV and an OR with LAF is effective in keeping MMA fume levels below those considered harmful by the U.S. Occupational Safety and Health Administration.

Space bound as well as earthbound spectroscopy of extra-terrestrial objects finds its challenge in light sources with low intensities. High transmission for every optical element along the light path requires optical materials with outstanding performance to enable the measurement of even a one-photon event. Using the Lunar Laser Ranging Project and the LIGO and VIRGO Gravitational Wave Detectors as examples, the influence of the optical properties of fused silica will be described. The Visible and Infrared Surveillance Telescope for Astronomy (VISTA) points out the material behavior in the NIR regime, where the chemical composition of optical materials changes the performance. Special fibers are often used in combination with optical elements as light guides to the spectroscopic application. In an extended spectral range between 350 and 2,200 nm Heraeus developed STU fiber preforms dedicated for broad band spectroscopy in astronomy. STU fibers in the broad spectral range as well as SSU fibers for UV transmission (180 – 400 nm) show also high gamma radiation resistance which allows space applications.

The mechanism of Ta seedlayer to promote (0002) texture in Ru underlayer was found to be mainly due to epitaxial growth of Ru (0002) on Ta (110) with a smooth surface. Relatively high sputtering power and low sputtering pressure as well as an optimized layer thickness are keys to deposit a Ta seedlayer, which can result in a good (0002) texture in Ru layer with a relatively thinner thickness. A Ru intermediate layer deposited at a higher pressure was found to further reduce the overall Ru underlayer thickness without degrading magnetic properties of CoCrPt-SiO2 perpendicular magnetic recording (PMR) layer. All these results were confirmed by the investigation of surface morphology, microstructure, crystal orientation, and magnetic properties, suggesting that through optimizing the deposition process of Ru/Ta layers, the magnetic spacing loss of PMR can be greatly suppressed

Es ist uns bekannt, dass in einigen Landern der Welt Zemente angeboten werden, die aus Kostengrunden nur in einer kleinen Region angeboten werden und uns daher schwer oder garnicht zuganglich sind. Im folgenden werden deshalb alle uns bekannten Knochenzemente aufgelistet (Tabelle 1). Es werden demnach auch die Zemente aufgefuhrt, die zum gegenwartigen Zeitpunkt eine lediglich untergeordnete Rolle spielen, nur in bestimmten Landern eingesetzt werden, bereits vom Markt genommen wurden, gerade zugelassen wurden oder trotz intensiver Bemuhungen fur uns nicht rechtzeitig erhaltlich waren (Cemex XL, Cemex Fluor LV und HV, CMW 2000, Sulcem 3 G, Antibiotic Simplex Tobramycin, Versabond). Laut Angaben von der Firma Sulzer sollen in Kurze auch die hochviskosen Varianten Sulcem 1 und Sulcem 1 G auf den Markt kommen.

The rapid expansion of wireless technology for commercial purposes, notably mobile telephony, has created a demand for low cost, high quality, fabrication processes and materials capable of use for microwave work. In this paper a thick-film process is described which not only meets the current requirements for wireless technology, but has been shown to offer outstanding potential for advanced integrated structures operating at higher microwave frequencies, into the mm-wave band. In addition, the paper addresses the key issues of material characterisation at microwave frequencies and describes some new techniques for obtaining accurate data on relative permittivity and loss tangent of thin dielectrics. Using this technique, measurements have been made on a new low loss low temperature co-fired ceramic (LTCC) material and results are reported. Measurements have also been made to establish the principal electrical properties of the material, namely dielectric loss, dielectric permittivity and line loss. The key measured data are: (i) very low loss tangent, 10/sup -4/ over the frequency range 8-12 GHz, (ii) consistent values of 3.9 for the dielectric relative permittivity, (iii) low line loss to at least 40 GHz, and (iv) low dispersion. Experimental work has also been carried out to compare the relative performance of etched and printed thick-film lines, using a range of substrates, including LTCC materials, over a wide range of frequencies. In particular, measured data on 50 ohm microstrip lines fabricated on alumina using the new thick-film gold technology gave line loss values varying from 0.005 dB/mm at 2 GHz to 0.033 dB/mm at 40 GHz, which is a further indication of the performance that is obtainable from the technology.

The sputtering process is one of the modern techniques for production of thin films as they are used in the technology of semiconductors, in processing of surfaces, etc. This process demands a high vacuum pump of the following qualities: (1) Easy to handle, (2) Stable and repeatable process conditions, (3) High pumping speed for all gases, especially for water vapor, (4) Ability to achieve a high vacuum environment before process begins (5×10−7 mbar), (5) Usable for process pressure up to 2×10−2 mbar, (6) Rapid evacuating of the process chamber from the process pressure down to a pressure 5×10−7 mbar after process is finished. Modern refrigerator-cooled cryopumps meet the requirements 1 to 4 without problems. Therefore the report especially deals with the 5th and 6th topics. Here special modifications are necessary compared to common cryopumps. There are two possibilities to cover the demand of using the pump at high pressures: (1) Using a refrigerator with high cooling capacity, (2) Installing a throttling valve into the cryopump. Both are discussed. Concerning topic six pumpdown plots of well designed cryopumps are shown. The conditions of the process were simulated while both argon and mixture of argon and hydrogen were let into a chamber. During the sputtering process hydrogen is produced by the process itself.