Harmunite, naturally occurring calcium ferrite CaFe2O4, was discovered in the Hatrurim Complex of pyrometamorphic larnite rocks close to the Jabel Harmun, the Judean Desert, West Bank, Palestinian ...Autonomy, Israel. The new mineral occurs in larnite pebbles of the pseudo-conglomerate, the cement of which consists of intensely altered larnite-bearing rocks. Srebrodolskite, magnesioferrite, and harmunite are intergrown forming black porous aggregates to the central part of the pebbles. Larnite, fluorellestadite, ye'elimite, fluormayenite, gehlenite, ternesite, and calciolangbeinite are the main associated minerals. Empirical crystal chemical formula of harmunite from type specimen is as follows Ca1.013(Fe3+1.957Al0.015Cr3+0.011Ti4+0.004 Mg0.003)Σ1.993O4. Calculated density is 4.404 g/cm3, microhardness VHN50 is 655 kg/mm2. The Raman spectrum of harmunite is similar to that of the synthetic analog. Harmunite in hand specimen is black and under reflected plane-polarized light is light gray with red internal reflections. Reflectance data for the COM wavelengths vary from approximately 22% (400 nm) to approximately 18% (700 nm). The crystal structure of harmunite Pnma; a = 9.2183(3), b = 3.0175(1), c = 10.6934(4) Å; Z = 4, V = 297.45(2) Å3, analogous to the synthetic counterpart, was refined from X-ray single-crystal data to R1 = 0.0262. The structure of CaFe2O4 consist of two symmetrically independent FeO6 octahedra connected over common edges, forming double rutile-type ∞1Fe2O6 chains. Four such double chains are further linked by common oxygen corners creating a tunnel-structure with large trigonal prismatic cavities occupied by Ca along 001. The strongest diffraction lines are as follows dhkl, (I): 2.6632 (100), 2.5244 (60), 2.6697 (52), 1.8335 (40), 2.5225 (35), 2.2318 (34), 1.8307 (27), 1.5098 (19). Crystallization of harmunite takes place in the presence of sulfate melt.
Introduction: AF self-care requires patients to perform daily self-monitoring for symptoms, practice decision making to address symptom changes, and adhere to prescribed medication, diet, physical ...activity, and follow-up care. Technology can facilitate these critical self-care behaviors and ultimately improve patient outcomes. We assessed atrial fibrillation (AF) patients’ experiences with a smartphone application (app) for AF self-management. Methods: A focus group with 9 AF patients and app users was conducted and analyzed using qualitative research methods. The focus group was recorded, transcribed, and coded using a priori and inductive coding strategies. Participant responses for each code were synthesized to identify primary themes. Results: We identified four superordinate themes from patients’ experiences: (1) disconnect between tool and its intended use; (2) app as acknowledged tool for adherence; (3) knowledge as empowerment; (3) motives: self-interest vs supporting research. Results from this qualitative study underscore the need to clarify the app’s intended use and to better accommodate patients with different AF experiences. The disconnect between a tool and its intended use can generate frustration for users. Discussion: The study reinforces that participants not only see how the app is a tool for adherence; they also see knowledge they gain via the app as empowering, suggesting a correlation between app use and self-efficacy.
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The crystal structure and the phase transition of noelbensonite ((Ba
0.72
Sr
0.31
Ca
0.01
)
Σ1.05
(Mn
1.82
Al
0.16
)
Σ1.98
Si
2
O
7
(OH)
2
·H
2
O) were investigated by
in situ
single-crystal X-ray ...diffraction,
ab initio
simulations, and infrared spectroscopy. In contrast to previous assumptions, single-crystal X-ray diffraction data and molecular dynamic simulations at room temperature (RT) displayed the acentric space group
P
2
1
cn, a
= 6.31303(2),
b
= 9.0977(3),
c
= 13.5820(4) Å,
V
= 779.73(4) Å
3
. This corresponds to the low-temperature (−118 °C) structure of lawsonite (CaAl
2
Si
2
O
7
(OH)
2
·H
2
O) and to the phase of hennomartinite (SrMn
+ 3
2
Si
2
O
7
(OH)
2
·H
2
O) below 95 °C. At 225 °C, the structure changed to space group
Cmcm
, which corresponds to that of hennomartinite at >245 °C and of lawsonite above 0 °C. In this structure the oxygen site of the H
2
O molecule showed positional disorder. Molecular dynamic simulations indicated that the splitting of this site reflects the disordered arrangement of the hydroxyl groups and the H
2
O molecule in the high-temperature modification. Infrared spectra collected at RT showed similarities with those of lawsonite. The bands at 3566 and 3517 cm
− 1
and the two broader bands between 3300 and 2930 cm
− 1
agree with the stretching frequencies of the hydrogen bond system as calculated from X-ray diffraction data and theoretical computations. Normal mode analysis of molecular dynamic trajectories allowed to identify the origin of vibration bands and polarization dependence of the IR spectra.
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Isomorphic nambulite, natronambulite, marsturite, and lithiomarsturite belong to the p-p (pectolite-pyroxene) series of pyroxenoid group minerals with five-periodic single chains of tetrahedra and ...the common simplified composition (Li,Na)(Mn,Ca)4Si5O14(OH) (Z = 2, space group P1). New crystal structure refinements including localization of H positions of four samples (two nambulite, one natronambulite, and one marsturite) with varying Li and Na concentrations and major to trace element compositional data from different localities are presented. Na occupies a strongly distorted eightfold-coordinated site (M5). Li replacing Na has a substantially smaller ionic radius and occupies a pocket of the large M5 coordination polyhedron and is only fivefold coordinated by oxygen. Thus, the Li ⇌ Na substitution has a significant influence on the bond-valence sums of oxygen sites forming the large cage around M5. Two of the cage-building oxygen sites (O1 and O11) are involved in hydrogen bonding. If M5 is occupied by Na or empty as in the closely related babingtonite, Ca2Fe2Si5O14(OH), the OH-group is at O1 and exhibits a strong hydrogen bond to O11. If a pocket of M5 is occupied by Li, the hydrogen bond system is reversed with OH at O11 and a strong hydrogen bond to O1. This study emphasizes that short hydrogen bonds with O-H···O separations of ca. 2.46 Å may be modified by homovalent substitution, which contributes to the understanding of strong hydrogen bonds and their role in the stability of hydrous pyroxenoids with strongly curled silicate chains.
This study investigated how goal frames (gain, non-loss, loss) either with or without efficacy statements affect consumers’ support for climate-change policy. Addressing the goal-framing literature’s ...difficulty in establishing a guiding theory with consistent findings, we (1) propose fear appeal theory as an alternative framework to guide goal-framing research; (2) test five fear appeal variables (fear, perceived threat, hope, perceived efficacy, and message processing) as mediators of goal-framing effects on policy support; and (3) highlight four common goal-framing confounds that may partly underlie the literature’s inconsistent findings. Aligning with fear appeal theory, results from a carefully controlled experiment revealed that a more threatening loss frame paired with an efficacy statement produced the strongest pro-policy attitudes and the greatest willingness-to-pay by successfully balancing fear/threat with hope/efficacy and by producing deeper message processing.
A new mineral was discovered in Cr–V-bearing marbles of the Sludyanka Complex from the Pereval marble quarry, Sludyanka district, southern Baikal region, Russia. It was named vanadio-pargasite as ...vanadium-bearing analog of pargasite according to the amphibole supergroup classification and CNMNC recommendations. Black Cr–V-spinel (magnesiocoulsonite–magnesiochromite), red Cr–V-bearing spinel, calcite, dolomite, Cr–V-bearing diopside and chlorite, phlogopite, and forsterite are associated minerals. Vanadio-pargasite occurs as subhedral long- and short-prismatic crystals 0.10–0.8 × 0.05–0.10 mm in size, with (110) and (010) faces and perfect cleavage by (110). Macroscopically, the new mineral is bright green to emerald green with vitreous luster; in thin sections and powder, it is pale green, without pleochroism. The new mineral is biaxial, positive, 2
V
= 86° ± 2°, γ = 1.659(2), β = 1.651(2), α = 1.643(2). The Mohs hardness is ~ 6, average VHN50;100 is 795; range 752–824 kg/mm2. The measured and calculated density is 3.05(5) and 3.112 g/cm3, respectively. In a thermogram over the range 654–1081°С, H2O is released with a endothermic effect. Over the range 900–1183°C, the main endothermic effect is caused by water and, possibly, F release, as well as melting of the mineral (1020°C). The absorption bands in the IR spectrum are, cm–1: 3445, 1633, 980, and 469. Vanadio-pargasite is monoclinic, space group 2C/m; the unit cell parameters are:
a
= 9.914(3),
b
= 18.003(2),
c
= 5.300(2) Å, β = 105.69(3)°,
V
= 910.7(5) Å
3
,
Z
= 2. The strongest reflections in the X-ray diffraction pattern are d, Å (I) (hkl): 8.98 (15) (020), 8.43 (40) (110), 3.27 (30) (240), 3.14 (100) (310), 2.82 (35) (330), 2.70 (18) (151), 2.34 (15) (
4.10
1
¯
), 1.898 (15) (510), 1.445 (25) (4.101). The average chemical composition (528 point analyses) is, wt %: 42.75 SiO
2
, 0.14 TiO
2
, 12.75 A1
2
O
3
, 0.44 Cr
2
O
3
, 5.92 V
2
O
3
, 19.15 MgO, 0.03 FeO, 0.01 MnO, 12.52 CaO, 3.45 Na
2
O, 0.41 K
2
O, 0.74 F (wet chem.) 1.75 H
2
O (calc.); the total is 99.91. The simplified formula is K
0.1
Na
0.9
Ca
2.0
Mg
4.0
V
0.7
Al
0.3
(Si
6.1
Al
1.9
)8.0O22(OH
1.7
F
0.3
)
2.0
. Holotype material has been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia (registration nos. 5035/1, 5035/2, and 5035/3).
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8.
Polytypism in xonotlite Ca6Si6O17(OH)2 Hejny, C.; Armbruster, Th
Zeitschrift für Kristallographie. Crystalline materials,
07/2001, Volume:
216, Issue:
7
Journal Article
Peer reviewed
Occurrence, chemistry, crystal growth, technical applications, structure and polytypism of xonotlite Ca
Si
(OH)
are reviewed. Atomic coordinates of the three simplest ordered polytypes in modified ...Gard notation:
(space group
2/
,
= 17.032,
= 7.363,
= 7.012 Å,
= 90.36°),
(space group
2/
,
= 17.032,
= 7.363,
= 14.023,
= 90.36°), and
(space group
1̅,
= 8.712,
= 7.363,
= 7.012 Å,
= 89.99°
= 90.36°,
= 102.18°) were modeled from geometric principles based on the known structure of the
polytype (space group A1̅,
= 8.712,
= 7.363,
= 14.023,
= 89.99
= 90.36,
= 102.18°). Unique reflection arrangements in the reciprocal lattice, characteristic of each polytype, were defined as criteria to identify xonotlite polytypes on X-ray single-crystal photographs. Precession- and Weissenberg-photographs of a xonotlite from the Kalahari manganese field (Republic of South Africa) indicated the predominance of the (100) twinned
polytype, followed by the
polytype, and very low concentrations of the
polytype. The
polytype could not be identified which agrees with previous electron diffraction experiments on xonotlites from other localities. Diffuse streaks parallel to
* and less intensive ones parallel to
* on single-crystal photographs suggest the presence of additional disordered polytypes.
The crystal structure of clinoptilolite from Weitendorf, Styria, Austria (a 17.622, b 17.895, c 7.399 Angstrom, beta 116.45 degrees, space group C2/m), ...(Mg0.9Ca1.4Sr0.1Ba0.3K1.2Na0.4)Al7Si29O72.25H2O, was studied by single-crystal XRD. The structures of a fully hydrated form (25 H2O) and three partially dehydrated forms with 7-5 H2O were refined at 100 K. The dehydration mechanism and the accompanying structural distortions are discussed.
The crystal chemistry of macfallite from Keweenaw County, Michigan was studied using electron microprobe, thermogravimetry (TG), differential thermal analysis (DTA), powder Fourier transform infrared ...(FTIR) spectroscopy, and single-crystal X-ray diffraction methods. The chemical formula derived from the electron-microprobe measurements is (Ca2.03 Na0.01)Σ2.04(Mn3+0.03 Al0.27 Mg0.09 Cu2+0.03 V3+0.01)Σ2.91Si3.05 O10.88(OH)3.12(Z = 2). An analysis using the intensities of the MnLβ and MnLα X-ray lines shows that most Mn is trivalent. The weight loss from TG measurement is 7.7 wt% at 1000°C, most of which is interpreted to be due to the loss of structural OH groups. The crystal structure of macfallite a = 8.959(3), b = 6.072(2), c = 10.218(4) Å, β = 110.75(3)°, space group P21/m, which is isostructural with sursassite, was refined using 1717 unique reflections to R = 4.1%. The site populations at the three independent octahedral sites, Mn1, Mn2, and Mn3, are Mn0.82 Al0.06 Mg0.09 Cu0.03, Mn0.75 Al0.25, and Mn0.95 Al0.05, respectively. In agreement with a bond-valence analysis, three crystal-chemically different OH groups are located at the O6, O10, and O11 positions. The site O7 is mostly occupied by oxygen, but minor amounts of hydroxyl may be located there as well. The powder FTIR spectrum in the region of the OH-stretching vibrations is characterized by three strong bands at 3413, 3376, and 3239 cm-1 and an additional broad absorption band around 2900 cm-1. The latter results from a relatively strong hydrogen bond, O6-H···O11, with a length of approximately 2.63 Å. Although there are three main hydroxyl groups occurring in macfallite, the exact number depends on the concentration of trivalent and divalent cations at the Mn1 site. If divalent cations occur at Mn1, a fourth OH group is necessary to maintain charge balance.
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