Black, White, and Grey

This study seeks to extend wicked problems analysis within the context of a library’s support for virtual reality (VR) and the related extended reality (XR) emerging technologies. The researchers conducted 11 interviews with 13 librarians, embedded IT staff, and/or faculty members who were involved in administering, managing, or planning a virtual reality lab or classroom in a library (or similar unit) in a higher education setting. The qualitative analysis of the interviews identified clusters of challenges, which are categorized as either emergent (but solvable) such as portability and training; complicated (but possible) such as licensing and ethics: and/or wicked (but tameable). The respondents framed their role in supporting the wickedness of VR/XR in three basic ways: library as gateway, library as learning partner, and library as maker. Five taming strategies were suggested from this research to help librarians wrestle with these challenges of advocating for a vision of VR/XR on their respective campuses. This research also hints at a larger role for librarians in the research of technology diffusion and what that might mean to their role in higher education in the future.

Zwitterion coordination to configurationally flexible d 10 cations: synthesis and characterization of tetrakis(betaine) complexes of divalent Zn, Cd, and Hg

The d 10 ions MII (M = Zn, Cd, Hg) and four equivalents of the neutral zwitterion trimethylglycine (betaine, bet) aggregate to discrete six-coordinated cationic complexes. With nitrate as counter anions, solids of the composition [M(bet)4](NO3)2·H2O are obtained. Their structural characterization reveals close relationship: they crystallize in metrically similar unit cells adopting three different subgroups of a hypothetical aristotype. In all cases, the divalent cations exhibit a strongly distorted coordination sphere in which two betaine ligands bind with both carboxylato O atoms and the other two with only one oxygen to the cation. Non-coordinating O atoms of different betaine ligands act as hydrogen bond acceptors towards co-crystallized water molecules. At least for the Pearson-soft HgII cations, this coordination is unexpected: to the best of our knowledge, HgII complexes with four carboxylato ligands have not yet been characterized. Without the necessity for charge balancing, the composition of zwitterion complexes is dominated by steric requirements and possibly by competition with alternative dipole molecules such as solvent water.

Hydrogen Bonds, Topologies, Energy Frameworks and Solubilities of Five Sorafenib Salts

Sorafenib (Sor) is an oral multi-kinase inhibitor, but its water solubility is very low. To improve its solubility, sorafenib hydrochloride hydrate, sorafenib hydrobromide and sorafenib hydrobromide hydrate were prepared in the mixed solvent of the corresponding acid solution, and tetrahydrofuran (THF). The crystal structures of sorafenib hydrochloride trihydrate (Sor·HCl.3H2O), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrochloride trihydrate, C21H17ClF3N4O3+·Cl−.3H2O (I), sorafenib hydrochloride monohydrate (Sor·HCl.H2O), C21H17ClF3N4O3+·Cl−.H2O (II), its solvated form (sorafenib hydrochloride monohydrate monotetrahydrofuran (Sor·HCl.H2O.THF), C21H17ClF3N4O3+·Cl−.H2O.C4H8O (III)), sorafenib hydrobromide (Sor·HBr), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrobromide, C21H17ClF3N4O3+·Br− (IV) and sorafenib hydrobromide monohydrate (Sor·HBr.H2O), C21H17ClF3N4O3+·Br−.H2O (V) were analysed. Their hydrogen bond systems and topologies were investigated. The results showed the distinct roles of water molecules in stabilizing their crystal structures. Moreover, (II) and (V) were isomorphous crystal structures with the same space group P21/n, and similar unit cell dimensions. The predicted morphologies of these forms based on the BFDH model matched well with experimental morphologies. The energy frameworks showed that (I), and (IV) might have better tabletability than (II) and (V). Moreover, the solubility and dissolution rate data exhibited an improvement in the solubility of these salts compared with the free drug.

Na2La4(NH2)14·NH3, a lanthanum-rich intermediate in the ammonothermal synthesis of LaN and the effect of ammonia loss on the crystal structure

Single crystals of Na2La4(NH2)14·NH3 were obtained from supercritical ammonia under ammonobasic conditions at a temperature of 573 K and 120 MPa pressure. It represents a lanthanum-rich intermediate in the ammonothermal synthesis of LaN. Upon aging, the title compound loses the crystal ammonia, resulting in pale crystals of Na2La4(NH2)14, the original space group P212121 being retained in a very similar unit cell. However, the crystal structure reacts to subtle changes in the composition as well as to the modified coordination of particularly the sodium cations interconnecting lanthanum amide layers within a third dimension. Results of Raman spectroscopic studies are reported. The observations of thermal analysis measurements indicating the formation of lanthanum nitride, in combination with the observed retrograde solubility in liquid ammonia, contribute to the knowledge of the ammonothermal crystal growth of lanthanum nitride.

The crystal structures, Hirshfeld surface analyses and energy frameworks of 8-{1-[3-(cyclopent-1-en-1-yl)benzyl]piperidin-4-yl}-2-methoxyquinoline and 8-{4-[3-(cyclopent-1-en-1-yl)benzyl]piperazin-1-yl}-2-methoxyquinoline

The title compounds, 8-{1-[3-(cyclopent-1-en-1-yl)benzyl]piperidin-4-yl}-2-methoxyquinoline, C27H30N2O (I), and 8-{4-[3-(cyclopent-1-en-1-yl)benzyl]piperazin-1-yl}-2-methoxyquinoline, C26H29N3O (II), differ only in the nature of the central six-membered ring: piperidine in I and piperazine in II. They are isoelectronic (CH cf. N) and isotypic; they both crystallize in the triclinic space group P\overline{1} with very similar unit-cell parameters. Both molecules have a curved shape and very similar conformations. In the biaryl group, the phenyl ring is inclined to the cyclopentene mean plane (r.m.s. deviations = 0.089 Å for I and 0.082 Å for II) by 15.83 (9) and 13.82 (6)° in I and II, respectively, and by 67.68 (6) and 69.47 (10)°, respectively, to the mean plane of the quinoline moiety (r.m.s. deviations = 0.034 Å for I and 0.038 Å for II). The piperazine ring in I and the piperidine ring in II have chair conformations. In the crystals of both compounds, molecules are linked by C—H...π interactions, forming chains in I and ribbons in II, both propagating along the b-axis direction. The principal contributions to the overall Hirshfeld surfaces involve H...H contacts at 67.5 and 65.9% for I and II, respectively. The major contribution to the intermolecular interactions in the crystals is from dispersion forces (E dis), reflecting the absence of classical hydrogen bonds.

Структура, термическая стабильность и транспортные свойства жаропрочного высокоэнтропийного сплава ZrTiHfNb

The problem of phase stability is one of the key problems in the study of high-entropy alloys. Here we address this issue for a heat-resistant high-entropy TiZrHfNb alloy with a bcc structure. The evolution of the structure of this alloy is studied during isothermal annealing at T = 400 °C. It was found that the as-cast alloy consists of two coexisting bcc phases with similar unit cell parameters. This state is homogenized during annealing. Still, the highly stressed nanostructured state is retained and the texture is enhanced. The thermal conductivity of the alloy in the temperature range of 20–400 °C changes in the range of 8–16 W m K, which is comparable in order of magnitude with the thermal conductivity of steels.

Scanning tunneling microscopy and spectroscopy of rubrene on clean and graphene-covered metal surfaces

Rubrene (C42H28) was adsorbed with submonolayer coverage on Pt(111), Au(111), and graphene-covered Pt(111). Adsorption phases and vibronic properties of C42H28 consistently reflect the progressive reduction of the molecule–substrate hybridization. Separate C42H28 clusters are observed on Pt(111) as well as broad molecular resonances. On Au(111) and graphene-covered Pt(111) compact molecular islands with similar unit cells of the superstructure characterize the adsorption phase. The highest occupied molecular orbital of C42H28 on Au(111) exhibits weak vibronic progression while unoccupied molecular resonances appear with a broad line shape. In contrast, vibronic subbands are present for both frontier orbitals of C42H28 on graphene. They are due to different molecular vibrational quanta with distinct Huang–Rhys factors.

Stochastic Analysis of a Computer System with Unit Wise Cold Standby Redundancy and Failure of Service Facility

Here, we analyze stochastically a computer system by taking one more similar unit (called computer system) in cold standby redundancy. The computer system consists of hardware and software components together. The provision of a single service facility has been made for repairing hardware and up-grading the software. The failure of the service facility is considered which resumes the jobs with full efficiency as new after availing treatment. The failure rates of hardware and software components as well as failure rate of the service facility are taken as constant and thus follow negative exponential distribution. The treatment rate of the service facility, repair rate of the hardware and up-gradation rate of the software follow arbitrary distributions with different probability density functions. Efforts have been made to determine reliability measures in steady state by using SMP and RPT. The behavior of MTSF, availability and also the profit function is observed graphically for some particular situations of the parameters.

Results of field studies of a tractor of traction class 1,4 with an elastic damping mechanism in a power drive

The topic of this paper is analyzing the results of field studies of a tractor with an elastic damping mechanism in a power drive and its operational efficiency assessment in comparison with a serial tractor. The subject of the research is a tractor with an elastic damping mechanism in a power drive as part of a plowing unit with a mounted plow. The purpose of this work is a detailed analysis of the influence of the parameters of the elastic-damping mechanism on the performance of a tractor with a plow. Carrying out such studies makes it possible to obtain new experimental data on the operation of the elastic damping mechanism in-stalled in the power drive of a tractor when aggregated with a plow. The control experiments were carried out in the same field during the summer and autumn peri-ods of one year. The benchmark for comparative experiments was the same tractor, but with a blocked elastic damping mechanism (for brevity, it is called “serial”). The results were processed on a personal computer using a software package. To analyze energy efficiency, a conditional classifi-cation of sample variability based on the coefficient of variation was used. Spectral analysis was performed to study numerical slip data. The indicators of the energy assessment show that the unit with an elastic damping mechanism in the power drive of the tractor has better performance (travel speed, productivity and fuel consump-tion per hectare) than a similar unit with a more rigid transmission. The elastic damping mechanism creates more favorable conditions for the formation of the nature of the load of the nodes, with un-steady and steady-state modes of motion. Statistical analysis of numerical data on slipping showed that the use of the mechanism makes it possible to reduce the mathematical expectation of slipping. Analysis of spectral characteristics indicates that the elastic-damping mechanism absorbs frequen-cies, being a filter when aggregated with various tools. Everything mentioned above indicates a sig-nificant improvement in the characteristics of the unit when using an elastic damping mechanism.

Isomorphous Crystals Formed by the Similar Supramolecular Motifs in Sorafenib Hydrochloride and Regorafenib Hydrochloride Salts

Sorafenib and regorafenib (or fluoro-sorafenib) are multikinase inhibitors active in the treatment of various human cancers, but their solubilities are very poor. To improve their solubilities, in this study, sorafenib hydrochloride (Sor·HCl, I) and regorafenib hydrochloride (Reg·HCl, II) have been prepared and their crystal structures were characterized. Their solubility properties in water were evaluated. Intriguingly, they are isomorphous crystal structures with the same space group and the similar unit cell dimensions, which were caused by the similar supramolecular patterns resulted by the formation of N–H···Cl− hydrogen bond instead of hydrogen bond between the protonated pyridinium cation and counterion. Moreover, the solubility properties displayed identical profiles. It may be concluded that a similar crystal structure leads to a comparable solubility profile.