The Effects of Thermal Metamorphism on the Amino Acid Content of the CI-Like Chondrite Y-86029

Carbonaceous chondrites con-tain a diverse suite of amino acids that varies in abundance and structural diversity depending on the degree of aqueous alteration and thermal histo-ry that the parent body experienced [1 - 3]. We recently determined the amino acid contents of several fragments of the Sutter's Mill CM2 chon-drite [4]. In contrast with most other CM2 chon-drites, the Sutter's Mill meteorites showed minimal evidence for the presence of indigenous amino acids. A notable difference between the Sutter's Mill meteorites and other CM2 chondrites are that the Sutter's Mill stones were heated to tempera-tures of 150 - 400 C [4], whereas most other CM2 chondrites do not show evidence for thermal met-amorphism [5]. Because empirical studies have shown that amino acids rapidly degrade in aqueous solutions above 150 C and the presence of miner-als accelerates this degradation [6], a plausible explanation for the lack of amino acids observed in the Sutter's Mill meteorites is that they were destroyed during metamorphic alteration. Fewer CI chondrites have been analyzed for amino acids because only a small number of these meteorites have been recovered. Nevertheless, indigenous amino acids have been reported in the CI chondrites Ivuna and Orgueil [7]. Here we report on the amino acid analysis of the CI-like chondrite, Yamato 86029 (Y-86029; sample size of 110 mg). Just as the Sutter's Mill meteorites were thermally metamporphosed CM2 chondrites, Y-86029 has experienced thermal metamorphism at higher temperatures than Orgueil and Ivuna (normal CI chondrites) experienced, possibly up to 600 C [8]

The effects of parent-body hydrothermal heating on amino acid abundances in CI-like chondrites

AbstractWe determined the amino acid abundances and enantiomeric compositions of the Antarctic CI1 carbonaceous chondrites Yamato (Y)-86029 and Y-980115, as well as the Ivuna and Orgueil CI1 carbonaceous chondrites by liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Y-86029 and Y-980115 both show evidence of parent-body heating (500–600 °C) in addition to aqueous alteration, while Ivuna and Orgueil only show evidence for aqueous alteration. In contrast to Ivuna and Orgueil, which each contain ∼70 nmol/g of amino acids in acid-hydrolyzed, water extracts, both heated Yamato CI meteorites contain only low levels of amino acids that were primarily l-enantiomers of proteinogenic amino acids, indicating that they are likely to be terrestrial in origin. Because indigenous amino acids have been found in meteorites that have experienced metamorphic temperatures of >1000 °C with only minimal aqueous alteration, heating alone is not sufficient to explain the lack of amino acids in Y-86029 and Y-980115. Rather, our data suggest that the combination of heating and aqueous alteration has a profound destructive effect on amino acids in meteorites. This finding has implications for the origins of amino acids and other molecules in the early evolution of our solar system

Additive Manufacturing of Biomechanically Tailored Meshes for Compliant Wearable and Implantable Devices

Additive manufacturing (AM) of medical devices such as orthopedic implants and hearing aids is highly attractive because of AM’s potential to match the complex form and mechanics of individual human bodies. Externally worn and implantable tissue-support devices, such as ankle or knee braces, and hernia repair mesh, offer a new opportunity for AM to mimic tissue-like mechanics and improve both patient outcomes and comfort. Here, it is demonstrated how explicit programming of the toolpath in an extrusion AM process can enable new, flexible mesh materials having digitally tailored mechanical properties and geometry. Meshes are fabricated by extrusion of thermoplastics, optionally with continuous fiber reinforcement, using a continuous toolpath that tailors the elasticity of unit cells of the mesh via incorporation of slack and modulation of filament-filament bonding. It is shown how the tensile mesh mechanics can be engineered to match the nonlinear response of muscle, incorporate printed mesh into an ankle brace with directionally specific inversion stiffness, and present further concepts for tailoring their 3D geometry for medical applications.Financial support was provided by a National Science Foundation Science, Engineering, and Education for Sustainability postdoctoral fellowship (Award number: 1415129) to S.W.P.; a Samsung Scholarship to J.L; the School of Engineering and Sciences from Tecnologico de Monterrey to R.R.; the Manufacturing Demonstration Facility, Oak Ridge National Laboratory, the Department of Energy, UT-Batelle, Oak Ridge Associated Universities, the DOE’s Advanced Manufacturing Office to G.D.; the German Academic Exchange Service (DAAD) to C.M.; and the Eric P. and Evelyn E. Newman Fund and NSF-CRCNS-1724135 to N.H

Discovery of the Orbit of the X-Ray Pulsar OAO 1657-415

Timing observations of the 38 s accreting X-ray pulsar OAO 1657-415 made with the BATSE large-area detectors on the Compton Gamma Ray Observatory have revealed a binary orbit with an X-ray eclipse by the stellar companion. Arrival time analysis of 20-60 keV data yielded the following best-fit orbital elements: P_(orb) = 10^d.4436 ± 0^d.0038, a_x sin i = 106.0 ± 0.5 lt-sec, e = 0.104 ± 0.005, ω = 93° ± 5°, T_(π/2) = JD 2,448,516.49 ± 0.05 TDB. From the pulsar mass function f_x(M) = 11.7 ± 0.2 M_⊙ and the measured eclipse half-angle θ_e = 29.7 ± 1.3 deg, we infer that the stellar companion is a supergiant of spectral class B0-B6. If the companion can be identified and its orbital velocity measured, the neutron star mass can be constrained. Both intrinsic spin-up and spin-down of the pulsar were measured during our observation

Infrared and optical observations of the newly identified Be/X-ray binary LSI + 61° 235

Observational (IR) and optical data are presented of the newly discovered Be/X-ray binary system LSI + 61° 235, taken over the period 1991 August – 1992 May. Though the IR shows little evidence for any changes, the optical Hα spectrum has undergone substantial modification. Combination of optical photometric measurements with the IR photometry allows the overall spectrum to be investigated and the existence of the Be star’s circumstellar disc to be directly confirmed

Gamma-Ray Continuum and Line Observations of Supernova 1987A

The Caltech gamma-ray imaging telescope observed the hard X-ray and gamma-ray emission from SN 1987A as it evolved between 1987 May and 1989 April, in a series of four balloon flights from Alice Springs, NT, Australia. Observations of the Crab Nebula and Pulsar provided in-flight data on pointing accuracy and instrument function for each flight. Results presented here include our measurements on 1987 November 18 (D268) and 1988 April 12 (D414) of both line emission at 847 and 1238 keV from the decay of ^(56)Co, and Compton scattered continuum above 50 keV. Upper limits for both line and continuum emission were obtained on 1987 May 20 (D86) and 1989 April 4 (D771). For the D268 and D414 continuum measurements our results are best-fit by a different~al p_ower law of the form dN/dE = kE^(-y)(c,^(-2)s^(-1)keV^(-1)for the energy range 50-800 keV. Our corresponding line measurements were fit with Gaussian profiles, containing additional terms for the underlying continuum. We compare our flux measurements and upper limits to those from other experiments and to predictions of theoretical models

An Observation of the Galactic Center Hard X-Ray Source, 1E 1740.7-2942, with the Caltech Coded-Aperture Telescope

The Galactic center region hard X-ray source 1E 1740.7-2942 has been observed with the Caltech Gamma-Ray Imaging Payload (GRIP) from Alice Springs, Australia, on 1988 April 12 and on 1989 April 3 and 4. We report here results from the 1989 measurements based on 14 hr of observation of the Galactic center region. The observations showed lE 1740.7 -2942 to be in its normal state, having a spectrum between 35 and 200 keV characterized by a power law with an exponent of -2.2 ± 0.3 and flux at 100 keV of (7.0 ± 0.7) x 10^(-s) cm^(-2) s^(-1) kev^(-1). No flux was detected above 200 keV. A search for time variability in the spectrum of lE 1740.7-2942 on one hour time scales showed no evidence for variability

Abulia following penetrating brain injury during endoscopic sinus surgery with disruption of the anterior cingulate circuit: Case report

Abstract Background It is common knowledge that the frontal lobes mediate complex human behavior and that damage to these regions can cause executive dysfunction, apathy, disinhibition and personality changes. However, it is less well known that subcortical structures such as the caudate and thalamus are part of functionally segregated fronto-subcortical circuits, that can also alter behavior after injury. Case presentation We present a 57 year old woman who suffered penetrating brain injury during endoscopic sinus surgery causing right basal ganglia injury which resulted in an abulic syndrome. Conclusion Abulia does not result solely from cortical injury but can occur after disruption anywhere in the anterior cingulate circuit – in the case of our patient, most prominently at the right caudate.</p