Study Design: Repeated measures analysis o i joint angle e i i~t s on hip and k n w muscle cltrtromyographic IEMGI activitv. Objectives: To simultan~~usly determine angle-dependent changes in maximal voluntary isometric contraction IMVICI torque and EMG activity during hip extension and knee ilexion. Background: Procedures ior normalizing EMG data and ior determining torque-angle relationships for various joint motions both entail asking suhjects to exert an MVIC. The implicit assumption in t h r w paradigms is that magnitude of the EMG response is at a constant, m.iximum level so that ohservcd angle-tlepcndmt variations in torque are due to mechanical iactors, such as muscle length and muscle moment arm.Methods and Measures: Fifty suhjects (25 men and 25 women1 particip.itcd in this study (age, 23.5 + 4.6 y; range, 18-38 y). Subjects periormed maximal isometric knee ilexion at 4 kncv angles and maximal isometric h~p extension at 4 hip angles. The dependent variahlrr were nnrmalizrd root-mean-square EMG and torque. The process ior normalizing EMG and torque data consisted o i determining the largc3t mean value ior each suhject across tcrting positions for the muscle o i interest. That value was designated as corrcqmnding to 100% MVIC, and all other data ior that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVICtorque and MVIC-EMG values ior each muscle group. Results: Mean torque-angle relationships were generally consistent with previous r e p m , though ~~n s i d e r d~l e intersuhject variability was observed. There were signiiicant .inglc-dependent diiierenccr in maximal EMG ior Ix)th the hamstring and gluteus maximus muscles. Worrell, Duke Universitv Medical Center, Deptartment oi Physical and Occupational Therapy PO 3965, Durham, NC 27710. E-mail: ~vorreOO6@mc.duke.edu xperimental approache.5 to the study of neuromuscular function frequently entail asking subjects to perform a maximal voluntary isornetric contraction (MVIC) of selected muscle groups. This approach is commonly used for amplitude normalization of electroinyographic (EMG) activity in order to determine the potential efficacv of various strengthening exercises by comparing the relative activity elicited by each e x e r c i~e . " . ' . ' .~"~ Maximal voluntary isometric contraction has also been used to determine in vivo torque-angle relationships of various joint motions by having subjects exert an MVIC at multiple points in the range of lnotion.~.~ t.21.22 The implicit assumption in these paradigms is that the instruction to perform an MVIC elicits a constant, rnaxi~nal level of motor iunit activity in the muscle of interest.The question of whether performance of an MVIC results in a

The classification of the tetrahedrite group minerals in keeping with the current IMA-accepted nomenclature rules is discussed. Tetrahedrite isotypes are cubic, with space group symmetry I43m. The general structural formula of minerals belonging to this group can be written as M(2)A6M(1)(B4C2)X(3) D4S(1)Y12S(2)Z, where A = Cu+, Ag+, ☐ (vacancy), and (Ag6)4+ clusters; B = Cu+, and Ag+; C = Zn2+, Fe2+, Hg2+, Cd2+, Mn2+, Cu2+, Cu+, and Fe3+; D = Sb3+, As3+, Bi3+, and Te4+; Y = S2– and Se2–; and Z = S 2–, Se2–, and ☐. The occurrence of both Me+ and Me2+ cations at the M(1) site, in a 4:2 atomic ratio, is a case of valency-imposed double site-occupancy. Consequently, different combinations of B and C constituents should be regarded as separate mineral species. The tetrahedrite group is divided into five different series on the basis of the A, B, D, and Y constituents, i.e., the tetrahedrite, tennantite, freibergite, hakite, and giraudite series. The nature of the dominant C constituent (the so-called “charge-compensating constituent”) is made explicit using a hyphenated suffix between parentheses. Rozhdestvenskayaite, arsenofreibergite, and goldfieldite could be the names of three other series. Eleven minerals belonging to the tetrahedrite group are considered as valid species: argentotennantite-(Zn), argentotetrahedrite-(Fe), kenoargentotetrahedrite-(Fe), giraudite-(Zn), goldfieldite, hakite-(Hg), rozhdestvenskayaite-(Zn), tennantite-(Fe), tennantite-(Zn), tetrahedrite-(Fe), and tetrahedrite-(Zn). Furthermore, annivite is formally discredited. Minerals corresponding to different end-member compositions should be approved as new mineral species by the IMA-CNMNC following the submission of regular proposals. The nomenclature and classification system of the tetrahedrite group, approved by the IMA-CNMNC, allows the full description of the chemical variability of the tetrahedrite minerals and it is able to convey important chemical information not only to mineralogists but also to ore geologists and industry professionals.

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publisher: Elsevier articletitle: The application of deep eutectic solvent ionic liquids for environmentally-friendly dissolution and recovery of precious metals journaltitle: Minerals Engineering articlelink: http://dx.doi.org/10.1016/j.mineng.2015.09.026 content_type: article copyright: Copyright © 2015 The Authors. Published by Elsevier Ltd

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