2,427 research outputs found
Studies on the respiratory pigment of Urechis eggs
Experiments previously reported (1) have shown that the eggs of the Pacific marine worm, Urechis caupo, contain a reversible oxidation-reduction pigment. The pigment, called urechrome, is autoxidizable and changes color from red to yellow on oxidation. It is soluble in water (reduced form insoluble below pH 5) and in acidified methanol, but insoluble in ether, acetone, chloroform, and neutral alcohol. Evidence for participation of the pigment in cellular respiration has been previously given
Moving wall, continuous flow electronphoresis apparatus
This invention relates generally to electrophoresis devices and more particularly to a moving wall, continuous flow device in which an electrophoresis chamber is angularly positionable with respect to the direction of moving belt walls. A frame with an electrophoresis chamber is rotatably supported between two synchronously driven belt walls. This allows the chamber to be angularly positionable with respect to the direction of belt travel, which compensates for electroosmotic flow within the electrophoresis chamber. Injection of a buffer solution via an opening and a homogenous sample stream via another opening is performed at the end of a chamber, and collection of buffer and the fractionated species particles is done by a conventional collection array at an opposite end of the chamber. Belts are driven at a rate which exactly matches the flow of buffer and sample through the chamber, which entrains the buffer to behave as a rigid electrophoretic medium, eliminating flow distortions (Poiseuille effect). Additionally, belt material for each belt is stored at one end of the device and is taken up by drive wheels at an opposite end. The novelty of this invention particularly lies in the electrophoresis chamber being angularly positionable between two moving belt walls in order to compensate for electroosmotic flow. Additionally, new belt material is continuously exposed within the chamber, minimizing flow distortion due to contamination of the belt material by the sample
Amplitude Variations in Pulsating Yellow Supergiants
It was recently discovered that the amplitudes of pulsating red giants and
supergiants vary significantly on time scales of 20-30 pulsation periods. Here,
we analyze the amplitude variability in 29 pulsating yellow supergiants (5 RVa,
4 RVb, 9 SRd, 7 long-period Cepheid, and 4 yellow hypergiant stars), using
visual observations from the AAVSO International Database, and Fourier and
wavelet analysis using the AAVSO's VSTAR package. We find that these stars vary
in amplitude by factors of up to 10 or more (but more typically 3-5), on a mean
time scale (L) of 33 +/- 4 pulsation periods (P). Each of the five sub-types
shows this same behavior, which is very similar to that of the pulsating red
giants, for which the median L/P was 31. For the RVb stars, the lengths of the
cycles of amplitude variability are the same as the long secondary periods, to
within the uncertainty of each.Comment: To be submitted to JAAVS
Preparative electrophoresis for space
A premise of continuous flow electrophoresis is that removal of buoyance-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chamber are used, distortion of the injected sample stream due to electrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field were not considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection
Hollow fiber clinostat for simulating microgravity in cell culture
A clinostat for simulating microgravity on cell systems carried in a fiber fixedly mounted in a rotatable culture vessel is disclosed. The clinostat is rotated horizontally along its longitudinal axis to simulate microgravity or vertically as a control response. Cells are injected into the fiber and the ends of the fiber are sealed and secured to spaced end pieces of a fiber holder assembly which consists of the end pieces, a hollow fiber, a culture vessel, and a tension spring with three alignment pins. The tension spring is positioned around the culture vessel with its ends abutting the end pieces for alignment of the spring. After the fiber is secured, the spring is decompressed to maintain tension on the fiber while it is being rotated. This assures that the fiber remains aligned along the axis of rotation. The fiber assembly is placed in the culture vessel and culture medium is added. The culture vessel is then inserted into the rotatable portion of the clinostat and subjected to rotate at selected rpms. The internal diameter of the hollow fiber determines the distance the cells are from the axis of rotation
Alien Registration- Bishop, Percy H. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/24286/thumbnail.jp
Continuous flow electrophoresis system experiments on shuttle flights STS-6 and STS-7
The development of a space continuous flow electrophoresis system (CFES) is discussed. The objectives of the experiment were: (1) to use a model sample material at a high concentration to evaluate the continuous flow electrophoresis process in the McDonnell Douglass CFES instrument and compare its separation resolution and sample throughput with related devices on Earth, and (2) to expand the basic knowledge of the limitations imposed by fluid flows and particle concentration effects on the electrophoresis process by careful design and evaluation of the space experiment. Hemoglobin and polysaccharide were selected as samples of concentration effects. The results from space show a large band spread of the high concentration of the single species of hemoglobin that was principally due to the mismatch of electrical conductivity between the sample and buffer
Evaluation of the impact of the STEM Ambassadors programme upon STEM Ambassadors
STEM Learning is the largest provider of STEM education and careers support to schools, colleges and community groups in the UK providing training, CPD sessions, free resources and governor support. The STEM Ambassador programme is one of STEM Learning’s ways of building young people’s awareness and interest in STEM careers. The programme is in its 20th year of being run by STEM Learning and with this, they have amassed over 25,000 STEM Ambassador volunteers from over 7,000 employers, who work with young people in schools and the community to provide the vital connection between STEM employers and young people. As long as you have experience within industry and/or STEM subjects you can be a STEM Ambassador, providing support in the form of workshops, mentoring, careers talks and enrichment days. The purpose of the evaluation that we undertook was to explore the Ambassadors’ experiences of the programme, the impact of the programme both on their volunteering and those they engage with and the effect of COVID-19 on the programme and shifts to virtual engagement. The evaluation found that motivations to participate in the programme were borne from wanting to raise awareness of STEM amongst young people and inspire the next generation. Young STEM Ambassadors in particular were seen to gain most skills from their volunteering roles and believed that volunteering was particularly important for their career progression. The STEM Ambassador programme was generally very well received by its volunteers who had adapted well to a virtual and hybrid version of their role during COVID-19, and it was expressed that many believed that their role had a positive impact on engaging schools and young people in STEM activities and careers
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