4,432 research outputs found
Effect of Water Content on the Thermal Inactivation Kinetics of Horseradish Peroxidase Freeze-Dried from Alkaline pH
The thermal inactivation of horseradish peroxidase freeze-dried from solutions of different pH (8, 10 and 11.5, measured at 25 C) and equilibrated to different water contents was studied in the temperature range from 110 to 150 C. The water contents studied (0.0, 1.4, 16.2 and 25.6 g water per 100 g of dry enzyme) corresponded to water activities of 0.0, 0.11, 0.76 and 0.88 at 4 C. The kinetics were well described by a double exponential model. The enzyme was generally more stable the lower the pH of the original solution, and for all pH values, the maximum stability was obtained at 1.4 g water/100 g dry enzyme. Values of z were generally independent of water content and of the pH of the original solution, and in the range of 15–25 °C, usually found in neutral conditions, with the exception of the enzyme freeze dried from pH 11.5 and equilibrated with phosphorus pentoxide, where a z-value of the stable fraction close to 10 C was found
RF MEMS Based Tunable Bowtie Shaped Substrate Integrated Waveguide Filter
A tunable bandpass filter based on a technique that utilizes substrate integrated waveguide (SIW) and double coupling is presented. The SIW based bandpass filter is implemented using a bowtie shaped resonator structure. The bowtie shaped filter exhibits similar performance as found in rectangular and circular shaped SIW based bandpass filters. This concept reduces the circuit foot print of SIW; along with miniaturization high quality factor is maintained by the structure. The design methodology for single-pole triangular resonator structure is presented. Two different inter-resonator couplings of the resonators are incorporated in the design of the two-pole bowtie shaped SIW bandpass filter, and switching between the two couplings using a packaged RF MEMS switch delivers the tunable filter. A tunning of 1 GHz is achieved for two frequency states of 6.3 and 7.3 GHz. The total size of the circuit is 70mm x 36mm x 0.787 mm (LxWxH)
A Global Event Description using Particle Flow with the CMS Detector
The CMS Detector consists of a large volume silicon tracker immersed in a
high four Tesla magnetic field, together with a high resolution/granularity
electromagnetic calorimeter and a nearly full solid angle coverage hadronic
calorimeter. Particle flow reconstruction provides a global pp-collision event
description by exploiting the combined information across all CMS
sub-detectors, optimizing the reconstruction and the identification of each
particle (photons, electrons, muons, unstable neutral hadrons, charged hadrons
and neutral hadrons) in an event. This summary introduces the CMS particle flow
algorithm, discusses the challenges associated with the LHC environment, and
presents some first example results in the context of hadronic decays of taus
as well as missing transverse energy.Comment: Poster at ICHEP08, Philadelphia, USA, July 2008. 3 page
Field Equations in the Complex Quaternion Spaces
The paper aims to adopt the complex quaternion and octonion to formulate the
field equations for electromagnetic and gravitational fields. Applying the
octonionic representation enables one single definition to combine some physics
contents of two fields, which were considered to be independent of each other
in the past. J. C. Maxwell applied simultaneously the vector terminology and
the quaternion analysis to depict the electromagnetic theory. This method
edified the paper to introduce the quaternion and octonion spaces into the
field theory, in order to describe the physical feature of electromagnetic and
gravitational fields, while their coordinates are able to be the complex
number. The octonion space can be separated into two subspaces, the quaternion
space and the S-quaternion space. In the quaternion space, it is able to infer
the field potential, field strength, field source, field equations, and so
forth, in the gravitational field. In the S-quaternion space, it is able to
deduce the field potential, field strength, field source, and so forth, in the
electromagnetic field. The results reveal that the quaternion space is
appropriate to describe the gravitational features; meanwhile the S-quaternion
space is proper to depict the electromagnetic features.Comment: arXiv admin note: substantial text overlap with arXiv:1503.0609
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