Superhalogen and Superacid

A superhalogen $\rm{F@C_{20}(CN)_{20}}$ and a corresponding Br{\o}nsted superacid were designed and investigated on DFT and DLPNO-CCSD(T) levels of theory. Calculated compounds have outstanding electron affinity and deprotonation energy, respectively. We consider superacid $\rm{H[F@C_{20}(CN)_{20}]}$ to be able to protonate molecular nitrogen. The stability of these structures is discussed, while some of the previous predictions concerning Br{\o}nsted superacids of record strength are doubted.Comment: 11 pages (main paper), 32 pages (supporting information), 10 figures, 10 tables, 62 reference

EXAFS studies of prostate cancer cell lines

Sulphur plays a vital role in every human organism. It is known, that sulphur-bearing compounds, such as for example cysteine and glutathione, play critical roles in development and progression of many diseases. Any alteration in sulphur's biochemistry could become a precursor of serious pathological conditions. One of such condition is prostate cancer, the most frequently diagnosed malignancy in the western world and the second leading cause of cancer related death in men. The purpose of presented studies was to examine what changes occur in the nearest chemical environment of sulphur in prostate cancer cell lines in comparison to healthy cells. The Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy was used, followed by theoretical calculations. The results of preliminary analysis is presented

Thermodynamic and Kinetic Aspects of Two- and Three-Electron Redox Processes Mediated by Nitrogen Atom Transfer

Treatment of (meso-tetra-p-tolylporphyrinato)manganese(V) nitride, (TTP)Mn==N, with (octaethylporphyrinato) manganese(II), Mn(OEP), in toluene leads to the reversible transfer of the nitrido ligand between the two metal complexes to form (OEP)Mn Nand Mn(TTP). The net result is a formal three-electron reduction of (TTP)MnvN to (TTP)Mn11• This occurs with a second-order rate constant of (5.6 ± 1.2) X 103 M-1 s-1 to form an equilibrium mixture with K~ = 1.2 ± 0.5 at 20 °C. The thermodynamic and activation parameters for this process are t:.H0 = 2.0 ± 0.2 kcalfmol, t:.S = 7 .I ± 0.6 calfmol·K, t:.H* = 9.4 ± 0.7 kcal/mol, and t:.S* = -10 ± 2 cal/mol·K. In THF at 20 °C, the equilibrium constant is 1.8 ± 0.2 and the rate constant drops to 2.3 ± 0.3 M-1 s-1• When a manganese(III) porphyrin complex is used as a reductant, reversible nitrogen atom transfer still occurs but mediates a formal two-electron process. At 22 °C, the exchange process between (TTP)MnCI and (OEP)Mn==N produces (TTP)Mn==N and (OEP)MnCI with a second-order rate constant of 0.010 ± 0.007 M-1 s-1 (t:.H* = 19 ± 2 kcal/mol and t:.S* = -3 ± 6 cal/mol·K) and forms an equilibrium mixture with Keq = 24.3 ± 3.3 (t:.H 0 = -7.0 ± 0.6 kcal/mol and t:.S 0 = -17 ± 2 cal/mol·K). Evidence for the formation of a binuclear wnitrido intermediate is presented for both processes. For the two-electron redox reaction, kinetic studies and mechanistic probes support a pathway which involves an initial chloride dissociation from the Mn(III) complex. Nitrogen atom transfer subsequently occurs between the Mn==N complex and the four-coordinate Mn(III) cationic species

First approach to studies of sulphur electron DOS in prostate cancer cell lines and tissues studied by XANES

Abstract Urological cancers comprise approximately one-third of all cancers diagnosed in men worldwide and out of these, prostate cancer is the most common one ( WHO World Cancer Report, 2008 ). Several risk factors such as age, hormone levels, environmental conditions and family history are suspected to play a role in the onset of this disease of otherwise obscure aetiology. It is therefore the medical need that drives multidisciplinary research in this field, carried out by means of various experimental and theoretical techniques. Out of many relevant factors, it is believed that sulphur can take an important part in cancer transformations. We have investigated the prostate cancer cell lines and tissues, along with selected organic and inorganic compounds used as references, by the X-ray absorption fine structure spectroscopy near the sulphur edge energy region. Particularly, the comparison of the experimental results collected during XANES measurements and theoretical calculations of electron density of states with use of the FEFF8 code and LAPW (linearised augmented plane-wave) method has been performed and in this work the first results of our studies are presented

Transmittance Measurement of a Heliostat Facility used in the Preflight Radiometric Calibration of Earth-Observing Sensors

Ball Aerospace and Technologies Corporation in Boulder, Colorado, has developed a heliostat facility that will be used to determine the preflight radiometric calibration of Earth-observing sensors that operate in the solar-reflective regime. While automatically tracking the Sun, the heliostat directs the solar beam inside a thermal vacuum chamber, where the sensor under test resides. The main advantage to using the Sun as the illumination source for preflight radiometric calibration is because it will also be the source of illumination when the sensor is in flight. This minimizes errors in the pre- and post-launch calibration due to spectral mismatches. It also allows the instrument under test to operate at irradiance values similar to those on orbit. The Remote Sensing Group at the University of Arizona measured the transmittance of the heliostat facility using three methods, the first of which is a relative measurement made using a hyperspectral portable spectroradiometer and well-calibrated reference panel. The second method is also a relative measurement, and uses a 12-channel automated solar radiometer. The final method is an absolute measurement using a hyperspectral spectroradiometer and reference panel combination, where the spectroradiometer is calibrated on site using a solar-radiation-based calibration

Directional Reflectance Studies in Support of the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley

The Radiometric Calibration Test Site (RadCaTS) is a suite of commercial and custom instruments used to make measurements of the surface reflectance and atmosphere throughout the day at Railroad Valley, Nevada. It was developed in response to the need for daily radiometric calibration data for the vast array of Earth-observing sensors on orbit, which is continuously increasing as more nations and private companies launch individual environmental satellites as well as large constellations. The current suite of instruments at RadCaTS includes five ground-viewing radiometers (GVRs), four of which view the surface in a nadir-viewing configuration. Many sensors such as those on Landsat-7 and Landsat-8 view Railroad Valley within 3 of nadir, while others such as those on Sentinel-2A and -2B, RapidEye, Aqua, Suomi NPP, and Terra can view Railroad Valley at off-nadir angles. Past efforts have shown that the surface bidirectional reflectance distribution function (BRDF) has minimal impact on vicarious calibration uncertainties for views <10, but the desire to use larger view angles has prompted the effort to develop a BRDF correction for data from RadCaTS. The current work investigates the application of Railroad Valley BRDF data derived from a BRF camera developed at the University of Arizona in the 1990s (but is no longer in use) to the current RadCaTS surface reflectance measurements. Also investigated are early results from directional reflectance studies using a mobile spectro-goniometer system during a round-robin field campaign in 2018. This work describes the preliminary results, the effects on current measurements, and the approach for future measurements

Human knee joint finite element model using a two bundle anterior cruciate ligament: Validation and gait analysis

Anterior cruciate ligament (ACL) deficient individuals are at a much higher risk of developing osteoarthritis (OA) compared to those with intact ACLs, likely due to altered biomechanical loading [1]. Research indicates the ACL is comprised of two “bundles”, the anteromedial (AM) and posterolateral (PL) bundles [2]. Although the function of both bundles is to restrain anterior tibial translation (ATT), each bundle has their own distinct range of knee flexion where they are most effective [3]. Articular cartilage contact stress measurements are difficult to measure in vivo. An alternative approach is to use knee joint finite element models (FEMs) to predict soft tissue stresses and strains throughout the knee. Initial and boundary conditions for these FEMs may be determined from knee joint kinematics estimated from motion analysis experiments. However, there is a lack of knee joint FEMs which include both AM and PL bundles to predict changes to articular cartilage contact pressures resulting from ACL injuries. The purpose of this study is to develop and validate a knee joint FEM using both AM and PL bundles and subsequently perform a gait analysis of varying ACL injuries

Development of a human knee joint finite element model to investigate cartilage stress during walking in obese and normal weight adults

Osteoarthritis (OA) is a degenerative condition characterized by the breakdown and loss of joint articular cartilage. While the cause of OA is not precisely known, obesity is a known risk factor [1]. Particular effort has gone towards understanding the relationship between obesity and knee OA because obesity is more strongly linked to OA at the knee than at any other lower extremity joint [2]. Although the relationship between obesity and knee OA is well established, the mechanism of pathogenesis is less understood. Excess body weight generates greater joint contact forces at the knee. However, obese individuals alter their gait, resulting in increased joint contact forces that are not proportional to body mass [3]. In this study, a partially validated knee joint finite element (FE) model was developed to predict cartilage loading during walking across individuals of varying adiposity. The model was used with kinematic and kinetic gait data to address the following hypotheses: 1) increased loading due to obesity will produce greater cartilage stress compared to the normal weight control; and 2) altered gait kinematics of obese individuals will alter the distribution of stress on the surface of the tibial cartilage