Mikecoxite, ideally (CHg4)OCl2, is the first mercury-oxide-chloride-carbide containing a C4- anion coordinated by four Hg atoms (a permercurated methane derivative) to be described as a mineral ...species. It was found at the McDermitt open-pit mine on the eastern margin of the McDermitt Caldera, Humboldt County, Nevada, U.S.A. It is monoclinic, space group P21/n, Z = 4; a = 10.164(5), b = 10.490(4), c = 6.547(3) Å, V 698.0(5) Å3. Chemical analysis by electron microprobe gave Hg 86.38, Cl 11.58, Br 0.46, C 1.81, sum = 100.23 wt%, and O was detected but the signal was too weak for quantitative chemical analysis. The empirical formula, calculated on the basis of Hg + Cl + Br = 6 apfu, is (C1.19Hg3.39)(Cl2.57Br0.05)1S2.62, and the ideal formula based on the chemical analysis and the crystal structure is (CHg4)OCl2. The seven strongest lines in the X-ray powder diffraction pattern are d (Å), I, (hkl): 2.884, 100, (230); 2.989, 81, (3̄01, 301, 1̄12, 112, 1̄31, 131); 2.673, 79, (1̄22, 122, 2̄12, 212); 1.7443, 40, (060, 4̄32, 432); 5.49, 34, (1̄01, 101); 4.65, 32, (120); 2.300, 30, (3̄12, 312). The Raman spectrum shows three bands at 638, 675, and 704 cm-1, well above the range characteristic of NHg4 stretching vibrations between 540 and 580 cm-1, that are assigned to CHg4 stretching vibrations. Mikecoxite forms intergrowths of bladed crystals up to 100 µm long that occur on granular quartz or in vugs associated with kleinite. It is black with a submetallic to metallic luster and strong specular reflections and does not fluoresce under short-or long-wave ultraviolet light. Neither cleavage nor parting were observed, and the calculated density is 8.58 g/cm3. In the crystal structure of mikecoxite, (C4-Hg42+) groups link through O2- ions to form three-membered rings that polymerize into corrugated CHg4OCl+ layers with near-linear C4--Hg2+-O and C4--Hg2+-Cl linkages. The layers link in the third direction directly via weak Hg2+-O2- and Hg2+-Cl- bonds to adjacent layers and also indirectly via interlayer Cl-. A bond-valence parameter has been derived for (Hg2+-C4-) bonds: Ro = 2.073 Å, b = 0.37, which gives bond-valence sums at the C4- ions in accord with the valence-sum rule. The source of carbon for mikecoxite in the volcanic high-desert environment of the type locality seems to be methane, with the reaction catalyzed by microbiota through full mercuration of carbon atoms, beyond the first stage that produces the volatile and highly mobile methylmercury, CH3Hg+, a potent neurotoxin that accumulates in marine food chains. Both the mineral and the mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2021-060). The mineral is named after Michael F. Cox (b. 1958), a founding member of the New Almaden Quicksilver County Park Association (NAQCPA) who was responsible for characterizing and remediating environmental mercury on-site and who recovered the rock containing the new mineral.
To evaluate long-term neurologic outcome in dogs with atlantoaxial subluxation (AAS) that were treated nonsurgically with a cervical splint.
Retrospective study.
19 dogs with AAS and managed with a ...cervical splint.
Medical records from 2 university hospitals were reviewed. Information pertaining to trauma, duration of clinical signs prior to admission, medical treatments prior to admission, results of neurologic and physical examinations at the time of admission, results of laboratory testing, results of diagnostic imaging, neurologic status at the time of discharge, duration of time the cervical splint was used for treatment, and neurologic status at the time of splint removal and at a final reexamination was extracted from the medical records. Long-term outcome was defined as neurologic status greater than or equal to 1 year after splint removal. Factors associated with a good or poor long-term outcome were determined.
A good final outcome was reported in 10 of 16 dogs. Median duration of clinical signs prior to referral was 30 days; dogs that were affected < or = 30 days were significantly more likely to have a good long-term outcome, compared with dogs affected > 30 days. The neurologic grade at admission, radiographic appearance of the dens, age at onset of clinical signs, and history were not associated with outcome.
Nonsurgical management of AAS by use of a cervical splint is a viable treatment modality for young dogs with a first episode of acute-onset clinical signs, regardless of the severity of neurologic deficits at admission.
We aimed to biomechanically evaluate the distal pronator quadratus and compare two locations of distal transection on the strength of the subsequent repair.
Eighteen fresh-frozen cadaveric specimens ...were dissected to the pronator quadratus muscle. Specimens were randomly allocated for transection of the pronator quadratus at the myotendinous junction (red group) or parallel to the myotendinous junction at the midsection of the distal tendinous zone (white group). For both groups, repair of the muscle was performed using two figure-of-8 sutures. The radius and ulna were positioned in 90° of wrist extension. The proximal muscular pronator quadratus was fixed in a cryo-clamp. Load-to-failure testing of the repair was performed at 1 mm/s with maximum amount of force applied to the pronator quadratus recorded for each specimen.
The pronator quadratus had a mean width, height, and area of 31.41 ± 5.74 mm, 53.79 ± 7.46 mm, and 1604.27 ± 429.20 mm2 respectively. The pronator quadratus distal tendinous zone had a mean width, height, and area of 29.71 ± 5.83 mm, 12.22 ± 2.79 mm, 282.94 ± 148.30 mm2 respectively. There was no significant difference between the two groups for pronator quadratus height, width, total area, or tendinous zone height, width, or total area. The average load to failure for the white group was significantly higher than that of the red group (29.46 ± 4.24 N vs. 13.78 N ± 6.66 N).
Incision and repair of the pronator quadratus in the distal tendinous region is stronger than incision and repair at the red myotendinous junction of the distal PQ.
•A more detailed cadaveric analysis of the Pronator Quadratus muscle.•A novel biomechanical testing apparatus utilizing a cryo-clamp mechanism.•Insight into the location of incisions of the pronator quadratus muscle.
We examine tidal modulation and back‐propagating fronts in simulated slow slip events using a rate and state friction law that is steady state velocity weakening at low slip rates and velocity ...strengthening at high slip rates. Tidal forcing causes a quasi‐sinusoidal modulation of the slip rate during the events, with the maximum moment rate occurring close to or slightly after the maximum applied stress. The amplitude of modulation scales linearly with the tidal load and increases as the tidal period increases relative to the timescale for state evolution. If we choose parameters so that the model matches the observed tidal modulation of slip in Cascadia, it can reproduce only a subset of the stress drops inferred from observations and only in a limited portion of parameter space. The tidal forcing also causes back‐propagating fronts to form and move back through the region that has already ruptured. The stress drop that drives these back‐propagating fronts sometimes comes from the tidal load and sometimes from a stress recovery that occurs behind the front in tidal and non‐tidal simulations. We investigate the slip and propagation rates in the back‐propagating fronts and compare them with observations. The modeled fronts propagate too slowly to be good representations of the fronts inferred from tremor observations. For the simulated fronts to propagate at the observed speeds, the stress drops driving them would have to be more than 70 % of the stress drop driving the forward‐propagating front.
Key Points
Quasi‐sinusoidal modulation with amplitude that scales with tidal load
Difficult to simultaneously match the observed tidal modulation and stress drops
Back‐propagating fronts exist but propagate more slowly than observed fronts
We report the finding of nanodiamonds, coexisting with amorphous carbon, in carbonaceous-chondrite (CC) material from the Kapoeta achondritic meteorite by Fourier-transform infrared (FTIR) ...spectroscopy and micro-Raman spectroscopy. In the C-H stretching region (3100-2600 cm−1), the FTIR spectrum of the Kapoeta CC material (KBr pellet) shows bands attributable to aliphatic CH2 and CH3 groups, and is very similar to IR spectra of organic matter in carbonaceous chondrites and the diffuse interstellar medium. Nanodiamonds, as evidenced by micro-Raman spectroscopy, were found in a dark region (∼400 m in size) in the KBr pellet. Micro-FTIR spectra collected from this region are dramatically different from the KBr-pellet spectrum, and their C-H stretching region is dominated by a strong and broad absorption band centered at ∼2886 cm−1 (3.47 m), very similar to that observed in IR absorption spectra of hydrocarbon dust in dense interstellar clouds. Micro-FTIR spectroscopy also indicates the presence of an aldehyde and a nitrile, and both of the molecules are ubiquitous in dense interstellar clouds. In addition, IR peaks in the 1500-800 cm−1 region are also observed, which may be attributed to different levels of nitrogen aggregation in diamonds. This is the first evidence for the presence of the 3.47 m interstellar IR band in meteorites. Our results further support the assignment of this band to tertiary CH groups on the surfaces of nanodiamonds. The presence of the above interstellar bands and the absence of shock features in the Kapoeta nanodiamonds, as indicated by Raman spectroscopy, suggest formation by a nebular-condensation process similar to chemical-vapor deposition.
Despite their clinical importance in maintaining the stability of the pinch mechanism, injuries of the radial collateral ligament (RCL) of the index finger may be underrecognized and underreported. ...The purpose of this biomechanical study was to compare the repair of index finger RCL tears with either a standard suture anchor or suture tape augmentation.
The index fingers from 24 fresh-frozen human cadavers underwent repair of torn RCLs using either a standard suture anchor or suture tape augmentation. Following the repairs, the initial displacement of the repair with a 3-N ulnar deviating load was evaluated. Next, the change in displacement (cyclic deformation) of the repair after 1,000 cycles of 3 N of ulnar deviating force was calculated (displacement of the 1000th cycle - displacement of the first cycle). Finally, the amount of force required to cause clinical failure (30° ulnar deviation) of the repair was determined.
Suture tape augmentation repairs displayed significantly less cyclic deformation (0.8 ± 0.5 mm) after cyclic loading than suture anchor repairs (1.8 ± 0.7 mm). There was no significant difference in the force required to cause the clinical failure of the repairs between the suture tape (35.1 ± 18.1 N) and suture anchor (24.5 ± 9.2 N) repairs.
Index finger RCL repair with suture tape augmentation results in decreased deformation with repetitive motion compared with RCL repair alone.
Suture tape augmentation may allow for early mobilization following index finger RCL repair by acting as a brace that protects the repaired ligament from deforming forces.
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