Spaced Rings Research Articles

Oxidant Stress during Simulated Ischemia Primes Cardiomyocytes for Cell Death during Reperfusion

Ischemia-reperfusion injury induces oxidant stress, and the burst of reactive oxygen species (ROS) production after reperfusion of ischemic myocardium is sufficient to induce cell death. Mitochondrial oxidant production may begin during ischemia prior to reperfusion because reducing equivalents accumulate and promote superoxide production. We utilized a ratiometric redox-sensitive protein sensor (heat shock protein 33 fluorescence resonance energy transfer (HSP-FRET)) to assess oxidant stress in cardiomyocytes during simulated ischemia. HSP-FRET consists of the cyan and yellow fluorescent protein fluorophores linked by the cysteine-containing regulatory domain from bacterial HSP-33. During ischemia, ROS-mediated oxidation of HSP-FRET was observed, along with a decrease in cellular reduced glutathione levels. These findings were corroborated by measurements using redox-sensitive green fluorescent protein, another protein thiol ratiometric sensor, which became 93% oxidized by the end of simulated ischemia. However, cell death did not occur during ischemia, indicating that this oxidant stress is not sufficient to induce death before reperfusion. However, interventions that attenuate ischemic oxidant stress, including antioxidants or scavengers of residual O(2) that attenuate/prevent ROS generation during ischemia, abrogated cell death during simulated reperfusion. These findings reveal that, in isolated cardiomyocytes, sublethal H(2)O(2) generation during simulated ischemia regulates cell death during simulated reperfusion, which is mediated by the reperfusion oxidant burst.

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Replacement arthroplasty of the radial head is indicated when fracture, deformity and/or arthrosis of the radiocapitellar joint is accompanied by posterolateral or axial instability. Collateral ligament instability derived from trauma or longstanding attenuation in conjunction with loss of axial support results in instability of the elbow and dysfunction. In the face of trauma restoration of columnar support at the radiocapitellar joint relies on the ability to reconstruct the radial head and neck. When this is impossible or following a failed attempt to do so, the result is pain, dysfunction and loss of control. With loss of the interosseous ligament, integrity longitudinal instability results in dysfunction more distally at the wrist as well as instability at the elbow. Silastic prosthetic replacement has been shown to be inadequate while soft tissue reconstruction alone is both difficult and unpredictable. Restoration of columnar support through replacement of the radial head has been effective in restoring stability but has relied upon standard sized prostheses, which do not always conform with anatomy. The authors have developed a radial head prosthetic system which closely approximates the native anatomy in terms of intramedullary fit, reestablishment of radial head height, and diameter accommodation to be able to adequately close soft tissue capsular and ligamentous structures without “overstuffing” the proximal radioulnar joint. The modular implant utilizes the concept of a central axis of forearm pronation and supination establishing a neck cut perpendicular to this long axis rather than perpendicular to the anatomic neck. This allows the replaced head to sit opposed to the capitellum at all times during pronation and supination. The radial head itself is sized to restore appropriate length longitudinally but is downsized at least 2 mm to allow adequate soft tissue closure, preventing overstuffing. A variety of sizes of stem and head length and width are provided in the “emergency trauma tray” with spacer rings of 1 mm and 2 mm to provide up to the 3 mm additional length as needed. For reconstruction cases, custom implants are measured and designed through markers placed on standardized x-rays and are constructed within five working days to provide an anatomic replacement exactly fitting the patient’s anatomy. The prosthetic head is easily removed from the stem for trial and sizing purposes. Each implant comes with its own set of instruments for exposure, broaches and inserters. Twenty-three patients with both acute and chronic pathology at the proximal radio-ulna and radiocapitellar joints with instability have been managed with this anatomic modular system. No patients have required revision. All have remained stable and pain relief has been significant with a decrease on a pain visual analog scale from an average of 8.5 to 1.2 and an increase in the arc of pronation and supination from 50° to 160°. There have been no infections. One patient has shown some lucency about the radial stem but clinically has had no symptoms of pain, instability or loosening. This system which attempts to recreate functional anatomy has proven to be effective in restoring stability while simplifying the surgical technique through use of user-friendly implants and surgical instrumentation. If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use). If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use).

Analysis of Lipolytic Protein Trafficking and Interactions in Adipocytes

This work examined the colocalization, trafficking, and interactions of key proteins involved in lipolysis during brief cAMP-dependent protein kinase A (PKA) activation. Double label immunofluorescence analysis of 3T3-L1 adipocytes indicated that PKA activation increases the translocation of hormonesensitive lipase (HSL) to perilipin A (Plin)-containing droplets and increases the colocalization of adipose tissue triglyceride lipase (Atgl) with its coactivator, Abhd5. Imaging of live 3T3-L1 preadipocytes transfected with Aquorea victoria-based fluorescent reporters demonstrated that HSL rapidly and specifically translocates to lipid droplets (LDs) containing Plin, and that this translocation is partially dependent on Plin phosphorylation. HSL closely, if not directly, interacts with Plin, as indicated by fluorescence resonance energy transfer (FRET) and bimolecular fluorescence complementation (BiFC) experiments. In contrast, tagged Atgl did not support FRET or BiFC with Plin, although it did modestly translocate to LDs upon stimulation. Abhd5 strongly interacted with Plin in the basal state, as indicated by FRET and BiFC. PKA activation rapidly (within minutes) decreased FRET between Abhd5 and Plin, and this decrease depended upon Plin phosphorylation. Together, these results indicate that Plin mediates hormone-stimulated lipolysis via direct and indirect mechanisms. Plin indirectly controls Atgl activity by regulating accessibility to its coactivator, Abhd5. In contrast, Plin directly regulates the access of HSL to substrate via close, if not direct, interactions. The differential interactions of HSL and Atgl with Plin and Abhd5 also explain the findings that following stimulation, HSL and Atgl are differentially enriched at specific LDs.

Life in the Universe: from the Miller Experiment to the Search for Life on Other Worlds

Life in the Universe: from the Miller Experiment to the Search for Life on Other Worlds

Multispectral imaging of ion transport in neutral carrier‐based cation‐selective membranes

High-resolution spectroscopic imaging of the cross section of ion-selective membranes during real-time electrochemical measurements is termed spectroelectrochemical microscopy (SpECM). SpECM is aimed for optimizing the experimental conditions in mass transport controlled ion-selective electrode (ISE) membranes for improved detection limit. The SpECM measurements are performed in a thin layer electrochemical cell. The key element of the cell is a membrane strip spacer ring assembly which forms a two compartment electrochemical cell. The cell is placed onto the stage of a microscope and the membrane strip is positioned in the center of the field of view. A slice of the image is focused onto the entrance slit of the imaging spectrometer. SpECM has been used for the determination of the diffusion coefficients of different membrane ingredients and for the quantitative assessment of the charged site concentrations in ISE membranes and membrane plasticizers. In addition, changes in the concentration profiles of the ionophore (free and complexed) and charged mobile sites inside the ISE membranes are documented upon the application of large external voltages. This account demonstrates the power and advantages of SpECM, a multispectral imaging method for investigations of mass transport processes in ISE membranes during electrochemical measurements.

Speaker having spacer ring inside frame

A speaker comprises: a magnetic circuit composed of a pot yoke, a magnet, and a pole piece; a diaphragm shaped conical, defining an outer periphery and an inner periphery, and having a surround half-rolled and fixedly disposed at the outer periphery and a voice coil bobbin with a voice coil wound thereon, fixedly disposed at the inner periphery; a spider having an outer diameter equal to or larger than the outer diameter of the surround; a frame having the magnetic circuit fixedly disposed at its central opening; and a spacer ring fixedly disposed inside the frame, and having a surround edge receiving portion adapted to fixedly receive the entire outer edge of the surround thereon.

Variable directional capacitor microphone comprising elastic acoustic resisting member

The present invention includes a variable directional capacitor microphone in which two capacitor elements are combined. Each of the capacitor elements includes a vibrating plate and a fixed electrode, and an acoustic resistance can be adjusted in the state that the microphone has been assembled. The variable directional capacitor microphone of this invention includes capacitor elements 10 a, 10 b. In each of the capacitor elements 10 a, 10 b, each of vibrating plate supporting members 12 a, 12 b, each of spacer rings 13 a, 13 b, each of fixed electrodes 14 a, 14 b having through holes 141 and each of pedestals 15 a, 15 b having a through hole in each center of the pedestals are assembled in this order, respectively, in each of ring-shaped cases 16 a, 16 b. Each of vibrating plates 11 a, 11 b is strained and fixed on each of vibrating plate supporting members 12 a, 12 b, respectively. The capacitor elements 10 a, 10 b are combined through a connecting ring 22 having female screw threads 221 with the pedestal 15 a, 15 b facing back-to-back. An elastic acoustic resisting member 31 is disposed between the pedestals 15 a, 15 b. The acoustic resistance of the acoustic resisting member 31 can be adjusted with the lengths of thread engagement of the pedestals 15 a, 15 b with the connecting ring 22.

Archaeology and direct imaging of exoplanets

The search for extraterrestrial technology effectively began 45 years ago with Frank Drake's Project Ozma and a radioastronomy start to the search for extraterrestrial intelligence (SETI). Eventually searches began for possible interstellar probes in stable orbits in the Solar System, as well as for infrared excesses from possible Dyson spheres round Sun-like stars. Whilst the Cold War was still underway, some scientists looked for evidence of nuclear waste dumps and nuclear wars elsewhere in the Milky Way. None of this work was carried out by archaeologists, even though by their very nature archaeologists are experts in the detection of ancient technologies. The technologies being searched for would have been partly ancient in age though advanced in techniques and science. The development of ESA's Darwin and NASA's TPF for detection and imaging of Earth-like exoplanets in our galactic neighbourhood represents an opportunity for the testing of techniques for detecting signatures of technological activities. Ideally, both Darwin and TPF might be able to provide spectroscopic data on the chemistry and biochemistry of the atmospheres of Earth-like exoplanets, and thus to detect some of the signs of life. If this can be accomplished successfully, then in theory evidence for pollution and nuclear accidents and wars should be detectable. Some infrared signatures of ETT on or round exoplanets might be detectable. Direct visual imaging of ETT structures will probably not be feasible till we have extremely powerful interstellar telescopes or actually send orbital craft.

Uniformly rotating rings in general relativity

In this paper, we discuss general relativistic, self-gravitating and uniformly rotating perfect fluid bodies with a toroidal topology (without central object). For the equations of state describing the fluid matter we consider polytropic as well as completely degenerate, perfect Fermi gas models. We find that the corresponding configurations possess similar properties to the homogeneous relativistic Dyson rings. On the one hand, there exists no limit to the mass for a given maximal mass-density inside the body. On the other hand, each model permits a quasistationary transition to the extreme Kerr black hole.

A Search for Dyson Spheres Around Late-type Stars in the Solar Neighborhood

We continued our search for partial (incomplete) Dyson spheres associated with solar-type stars (spectral types F, G and K) within 25 pc of the Sun. No candidate objects were found in a total of 384 stars.

A facile synthesis route for carboxyaryl-methacrylates: a way to obtain aromatic polyelectrolytes

This paper describes a flexible synthetic route for the preparation of the following methacrylic acid derivative monomers with aromatic spacers, including salicylic acid derivatives, in high yields: 2-methacryloyloxybenzoic acid (2-MBA), methyl-2-methacryloyloxybenzoate (M2-MB), 3-methacryloyloxybenzoic acid (3-MBA), methyl-3-methacryloyloxybenzoate (M3-MB), 4-methacryloyloxybenzoic acid (4-MBA), methyl-4-methacryloyloxybenzoate (M4-MB), 4-methacryloyloxy phenyl acetic acid (4-MPAA), methyl-4-methacryloyloxyphenylacetate (M4-MPA) and methyl-4-methacryloyloxyphenylpropionate (M4-MPP). The preparation of the respective aromatic polymers from these monomers by solution free-radical polymerization and their characterization are also described. The position of the substituent in the aromatic spacer ring plays a very important role in the properties of the polymers prepared. While for methyl-ester substitution the glass transition temperature increases from ortho to para isomers, in the case of carboxylic acid substitution this value decreases from ortho to para isomers. The four polymers prepared with free acid groups are hydrophobic polyelectrolytes, as shown by their behavior in aqueous NaCl solutions at different pH values, making them potential candidates for new pH sensitive materials.

Dynamic shear stress of tough-pitch copper at high strain and high strain-rate

Dynamic shear tests for the tough-pitch copper at high strain and high strain rate was performed. The Split Hopkinson Pressure Bar (SHPB) compression test system was modified to yield a shear deformation in the specimen. Hat-shaped specimens for the tough-pitch copper were adopted to generate high strain of γ=3–4 and high strain-rate of γ=104/s. The dynamic analysis by ABAQUS 5.5/EXPLICIT code verified that shear zone can be localized in hat-shaped specimens. A proper impact velocity and the axial length of the shear localization region were determined through the elastic wave analysis. The displacement in a hat-shaped specimen is limited by a spacer ring which was installed between the specimen and the incident bar. The shear bands were obtained by measuring the direction of shear deformation and the width of deformed grain in the shear zone. The decrease of specimen length has been measured on the optical displacement transducer. Dynamic shear stress-strain relations in the tough-pitch copper were obtained at two strain-rates.

Uniformly rotating axisymmetric fluid configurations bifurcating from highly flattened Maclaurin spheroids

We give a thorough investigation of sequences of uniformly rotating, homogeneous axisymmetric Newtonian equilibrium configurations that bifurcate from highly flattened Maclaurin spheroids. Each one of these sequences possesses a mass-shedding limit. Starting at this point, the sequences proceed towards the Maclaurin sequence and beyond. The first sequence leads to the well known Dyson rings, whereas the end points of the higher sequences are characterized by the formation of a two-body system, either a core-ring system (for the second, the fourth etc. sequence) or a two-ring system (for the third, the fifth etc. sequence). Although the general qualitative picture drawn by Eriguchi and Hachisu in the eighties has been confirmed, slight differences turned out in the interpretation of the origin of the first two-ring sequence and in the general appearance of fluid bodies belonging to higher sequences.

Synthesis and Antitumor Activity of Thieno-Separated Tricyclic Purines

The purine ring system is undoubtedly one of the most ubiquitous heterocyclic ring systems in nature as it has the distinction of being the parent ring in countless derivatives of biological relevance. It is not surprising then that modified purines possess the potential to impact several areas, including a better understanding of the biological effects of DNA damaging agents, enzyme/substrate interactions, and in the development of more potent medicinal agents. One focus for our research at Georgia Tech has centered around the design and synthesis of a series of extended purine analogues containing a heterocyclic spacer ring, with sites set on investigations into their use as (i) potential anticancer and antiviral agents, (ii) dimensional probes for enzyme and coenzyme binding sites, and (iii) structural probes of the minor groove of DNA. The synthesis and preliminary antitumor activity of two thieno-separated purine analogues are described herein. Tricyclic 1 was synthesized in 12 steps from tribromoimidazole and with an overall yield of 7%. Tricyclic 2 was synthesized in 9 steps with an overall yield of 13%. Both 1 and 2 exhibited growth inhibitory effects on HCT116 colorectal cancer cells in vitro.

A search of the IRAS database for evidence of Dyson Spheres

One of the forms of astroengineering activity that a very advanced civilization could possibly carry on is the constructions of huge “buildings” in space around the central star. Historically such constructions are called Dyson Spheres. We would like to introduce a new name — Astroengineering Constructions (AC) — to mean a more general type of construction not necessarily related to any specific star. AC absorb energy from different types of activity and re-emit it as infrared radiation, i.e. radiation lying in the submillimeter and millimeter range. Further, AC are expect to have spectra similar to the black-body spectra because they re-emit all the energy that they absorb, although in the infrared range, as already mentioned. Thus, the effective temperature of these Planckian distributions is expected to lie between 3–300 K with the spectrum peaking between 10 μm and 10 mm. We have analyzed the IRAS database and extracted a catalog of sources whose spectra are similar to the black-body emission. The catalog of these sources and their preliminary parameters are discussed. The distribution of the color temperatures of IRAS sources and the sky distribution of sources are also considered. The possibility of the distinction of AC from thick circumstellar dust shells around red giant stars is discussed.

A program to search for dyson spheres with the infrared space observatory

A contribution to the Search for Extraterrestrial Intelligence is made by searching for astro-engineering products (Dyson spheres) of advanced civilizations using the Infrared Space Observatory (ISO) satellite. ISO is the European infrared astronomy mission covering the wavelength region of 2–240 microns. A SETI program using 1 h 18 m total spacecraft time has been established and will be described. The program will be the first attempt to perform active SETI in the infrared using a spacecraft. A photometric survey, covering 3–60 microns, of several old main sequence stars will be performed in order to assess infrared excesses compatible with the presence of large astro-engineering products like Dyson spheres that emit a blackbody temperature of several hundred K. This survey shall identify candidates for Dyson spheres. In addition, a few objects which are known to show infrared excesses in the 12 or 25 micron IRAS measurements are considered for a detailed photometric investigation. The usage of the ISO satellite is crucial for the success of the program as only ISO currently offers, with its infrared photometer, the high sensitivity that is needed to detect the radiation of cold artificial structures superimposed on the several thousand K blackbody background spectrum of the host star.

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

On the radius of Dyson's sphere

Two assumptions were accepted in this paper. First, the ambient temperature on the Dyson sphere (DS) is close to the physiological optimum of human beings. Second, a proper DS “design” should allow the highest possible efficiency of power generation. It was proved that no optimum DS radius exists but that there is a minimum DS radius, whose value is a function of the ambient temperature only. Reasonable DS radii are characterized by efficiencies of power generation less than 10% and differences between the DS inner and outer surface temperature of tens of Kelvin.

蒸気タービン部品のウォータジェット切断加工技術の開発

Electrical discharge machines (EDM) have conventionally been used for cutting the nozzle blade holes in steam turbine diaphragm spacer rings due to high precision requrements. Problems assosiated with this method are slow cutting speed and a potential for fire resulting from the usage of oil. The abrasive water jet (AWJ) machine avoids these problems makes it possible to cut three-dimensional curved work pieces in the horizontal position. This is performed by utilizing two heads with each head featuring simultaneous control in five axes. AWJ technology makes relatively high speed cutting possible while maintaining high precision requirements. The results obtained are summarized as follows;(1) Abrasive water jet cutting technology and equipment have been established to perform precision cutting of three-dimensional curved surfaces while obtaining higher productivity than the conventional EDM method. The use of two cutting heads with individual simultaneous cotrol in five axes makes this technology possible.(2) A significant man hour reduction has been achieved as a result of increased productivity by utilizing high speed cutting (10 to 50 mm/min) along the nozzle blade profiles.(3) AWJ cut surfaces exhibit approximately 1/5 the surface roughness of conventional EDM cut surfaces. The accuracy of the cut hole geometry satisfies specification requirements for maximum allowable gap between the nozzle and hole profile.(4) Because no oil is used with AWJ cutting, the danger of fire has been eliminated and environmental compatability is improved.

Low-stress gold electroplating for x-ray masks

We present a method for obtaining electrodeposited Au films of uniform thickness, low stress, and fine grain using a safe, commercially-available plating solution. In our electroplating set-up, the plating geometry is fixed by inserting an annular spacer ring between the Pt anode and the sample to be plated. Plating using this electrode configuration and a stagnant solution yields uniform-thickness Au films with a simple linear relationship between film stress and plating current density. Such films are well-suited as mask absorbers for x-ray nanolithography (sub-100-nm feature sizes).