Influence of thermochemistry on Mach reflection in hypersonic flow

Real gas thermochemistry can significantly impact the aerodynamics of hypersonic systems. For example, shock stand-off distance in front of a blunt body has been shown to depend on the degree of chemical dissociation. High temperature effects can also alter shock-shock interaction phenomena, but the degree of the modification and its consequences can be challenging to predict. Sanderson et al. experimentally investigated oblique shock impingment on a bow shock (Edney type IV configuration) in a flow with significant gas dissociation. Previous studies had suggested significant increase in heat transfer at jet impingement due to real gas effects, however, experiments showed no dependence of peak heat transfer rate on stagnation enthalpy. The influence of nonequilibrium gas chemistry on Mach and regular shock reflection has been investigated in a number of numerical studies. Burtschell et al. numerically investigated a wedge geometry located in a Mach 7 free stream, a setup similar to that used in the present experimental work. Mach stem height and hysteresis behavior was examined. Burtschell et al. found a strong dependence of transition angles, Mach stem height and location on the gas flow model. For a given wedge angle, the inclusion of real gas chemistry led to a significant decrease in Mach stem height. Chemical-vibration coupling, however, slightly increased the height of the Mach stem. Direct Monte-Carlo simulations of a shock reflection with and without real gas effects carried out by Gimelschein et al. also found a substantial effect on Mach stem height and transition angle. However, an experimental study in dissociating nitrogen and carbon dioxide, ionizing argon and frozen argon could detect no effect on the transition condition due to finite relaxation length at the conditions of the experiment. In the present work, we experimentally investigate a Mach reflection generated by two opposing wedges in a Mach 7.1 free stream. The main goal of this work is to determine directly what kinds of real gas effects occur behind a normal shock in a Mach reflection configuration for a previously selected run condition. Experiments are carried out in an expansion tube facility which is capable of simulating high enthalpy hypersonic flight conditions, and a significant degree of vibrational excitation and chemical dissociation are expected behind the normal shock. In high enthalpy gas flows, emission spectroscopy can be used to characterize the test gas composition and thermodynamic state. As impulse facilities, expansion tubes produce a challenging experimental environment for probe measurements with issues such as short test times, high temperatures and velocities, and diaphragm fragmentation. The non-intrusive nature of spectroscopy makes it an attractive technique for determining flow field properties in impulse facilities. Spectrally resolved studies have been previously used as a means towards characterizing high-enthalpy run conditions. Work completed at the X1 and X2 superorbital expansion tube facilities used emission spectroscopy to measure electron number density behind a bow shock and to identify sources of visible radiation. Time-resolved spectral methods were used in the JX1 expansion tube facility to determine the useful test time. Using the CARS technique, temperature profiles were determined for a hypervelocity blunt body flow field using the T3 shock tunnel facility. Using the free piston shock tube/tunnel facility TCM2, laser spectroscopy was used for species identification and shock front temperature profile diagnostics and spontaneous Raman spectroscopy was used to analyze the self-luminosity of nitrogen hypersonic flows for varying enthalpy conditions. In the current experiments, asymmetric wedges are used to generate a Mach stem, with a free shear layer at each triple point. Imaged spectroscopic measurements behind the Mach stem are presented. The spectra confirms flow dissociation and verifies the appropriateness of a run condition which in the future is to be used towards investigating high-temperature effects upon shear layer structure in hypersonic flow

Critical behaviour of the 1D q-state Potts model with long-range interactions

The critical behaviour of the one-dimensional q-state Potts model with long-range interactions decaying with distance r as $r^{-(1+\sigma)}$ has been studied in the wide range of parameters $0 < \sigma \le 1$ and $\frac{1}{16} \le q \le 64$. A transfer matrix has been constructed for a truncated range of interactions for integer and continuous q, and finite range scaling has been applied. Results for the phase diagram and the correlation length critical exponent are presented.Comment: 20 pages plus 4 figures, Late

Critical behavior of the long-range Ising chain from the largest-cluster probability distribution

Monte Carlo simulations of the 1D Ising model with ferromagnetic interactions decaying with distance $r$ as $1/r^{1+\sigma}$ are performed by applying the Swendsen-Wang cluster algorithm with cumulative probabilities. The critical behavior in the non-classical critical regime corresponding to $0.5 <\sigma < 1$ is derived from the finite-size scaling analysis of the largest cluster.Comment: 4 pages, 2 figures, in RevTeX, to appear in Phys. Rev. E (Feb 2001

Targeting CD133 In Androgen Receptor Indifferent, Neuroendocrine Differentiated Aggressive Variant Prostate Cancer

University of Minnesota Ph.D. dissertation. June 2019. Major: Pharmacology. Advisor: Aaron LeBeau. 1 computer file (PDF); xi, 121 pages.An increasing number of men are developing a lethal, non-androgen receptor (AR) driven form of prostate cancer (PCa) known as aggressive variant prostate cancer (AVPC). Therapeutic options for AVPC are limited, and the development of novel therapeutics is significantly hindered by the inability to accurately monitor the disease through imaging. This underscores the critical need to develop improved imaging agents for AVPC. Targeted imaging agents, such as those developed for prostate-specific membrane antigen (PSMA) have made significant progress in imaging metastatic prostate adenocarcinoma; however, numerous studies have shown that non-AR driven prostate cancer does not express PSMA. Thus, there is an urgent unmet need to identify novel antigens and targeted imaging agents for the detection and monitoring of this lethal form of PCa. In these studies, we have identified the pentaspan transmembrane glycoprotein, CD133, as a targetable antigen that is overexpressed on the surface of non-AR driven, neuroendocrine-differentiated prostate cancer. Additionally, we have developed a novel antibody, termed HA10 IgG, which was found to bind to a glycosylation-independent epitope on CD133. HA10 IgG was validated in numerous cell lines and demonstrated similar or more accurate binding to CD133 when compared to a frequently used commercial antibody in vitro. To assess the imaging potential of HA10 IgG, the antibody was labeled for near-infrared and positron emission tomography imaging. Our CD133 probe was validated in imaging studies and shown to be highly selective for CD133-expressing PCa cells, suggesting its potential as a non-invasive imaging agent for lethal, non-AR-driven AVPC

NO and OH Spectroscopic Vibrational Temperature Measurements in a Post-Shock Relaxation Region

In this paper, spatial temperature profiles are examined in the nonequilibrium relaxation region behind a stationary shock wave in a hypervelocity air Mach 7.42 freestream. The normal shock wave is established through a Mach reflection from an opposing wedge arrangement in an expansion tube facility. Schlieren images confirm that the shock configuration is steady and the location is repeatable. Emission spectroscopy is used to identify dissociated species and to make vibrational temperature measurements using both the nitric oxide and the hydroxyl radical A-X band sequences. Temperature measurements are presented at selected locations behind the normal shock. LIFBASE is used as the simulation spectrum software for OH temperature-fitting; however, the need to access higher vibrational and rotational levels for NO leads to the use of an in-house developed algorithm. For NO, results demonstrate the contribution of higher vibrational and rotational levels to the spectra at the conditions of this study. Very good agreement is achieved between the experimentally measured NO vibrational temperatures and calculations performed using an existing state-resolved, three-dimensional forced-harmonic oscillator thermochemical model. The measured NO vibrational temperatures are significantly higher than the OH temperatures

Expansion Tube Investigation of Shock Stand-Off Distances in High-Enthalpy CO_2 Flow Over Blunt Bodies

The shock standoff distance in front of a blunt body is sensitive to the thermochemical state of the free stream. Recently, experimental and numerical studies have reported significantly different bow shock profiles in high-enthalpy carbon dioxide flows, a discrepancy that may result from non-equilibrium processes during flow acceleration in ground-based facilities. In this work, an expansion tube is used to create a Mach 5.7 carbon dioxide flow, matching the stagnation enthalpy and the velocity of previous studies. Images of shock layers are obtained for spherical geometries and a scaled model of the Mars Science Lander. Different sphere diameters are used in order to access non-equilibrium and equilibrium stagnation line shock profiles predicted by theory. Mars Science Lander profiles at zero angle of attack are in good agreement with available data from the LENS X expansion tunnel facility, confirming results are facility-independent for the same type of flow acceleration, and indicating the flow velocity is a suitable first-order matching parameter for comparative testing. Heat transfer measurements on the Mars Science Lander are also presented for the three different angle of attacks, and the results are consistent with previous studies. Initial results from a proposed organo-metallic based emission spectroscopy technique for bow shock layer interrogation are also presented

Quantum oscillations of the magnetic torque in the nodal-line Dirac semimetal ZrSiS

We report a study of quantum oscillations (QO) in the magnetic torque of the nodal-line Dirac semimetal ZrSiS in the magnetic fields up to 35 T and the temperature range from 40 K down to 2 K, enabling high resolution mapping of the Fermi surface (FS) topology in the $k_z=\pi$ (Z-R-A) plane of the first Brillouin zone (FBZ). It is found that the oscillatory part of the measured magnetic torque signal consists of low frequency (LF) contributions (frequencies up to 1000 T) and high frequency (HF) contributions (several clusters of frequencies from 7-22 kT). Increased resolution and angle-resolved measurements allow us to show that the high oscillation frequencies originate from magnetic breakdown (MB) orbits involving clusters of individual $\alpha$ hole and $\beta$ electron pockets from the diamond shaped FS in the Z-R-A plane. Analyzing the HF oscillations we have unequivocally shown that the QO frequency from the dog-bone shaped Fermi pocket ($\beta$ pocket) amounts $\beta=591(15)$ T. Our findings suggest that most of the frequencies in the LF part of QO can also be explained by MB orbits when intraband tunneling in the dog-bone shaped $\beta$ electron pocket is taken into account. Our results give a new understanding of the novel properties of the FS of the nodal-line Dirac semimetal ZrSiS and sister compounds

Centaurea triumfetii essential oil chemical composition, comparative analysis, and antimicrobial activity of selected compounds

The essential oils from the Centaurea genus are well known for their pharmacological properties. The most abundant and dominant chemical components in Centaurea essential oils are ß-caryophyllene, hexadecanoic acid, spathulenol, pentacosane, caryophyllene oxide, and phytol. However, whether these dominant components are the key drivers for observed antimicrobial activity remains unclear. Thus, the aim of this study was dual. Here we provide comprehensive, literature-based data to correlate the chemical compounds in Centaurea essential oils with the tested antimicrobial activity. Secondly, we characterized the essential oil of Centaurea triumfettii All. squarrose knapweed using coupled system gas chromatography-mass spectrometry and tested its phytochemicals for antimicrobial activity against E. coli and S. epidermis using disc diffusion assay and monitoring their growth in Muller Hinton broth. The most abundant compounds in C. triumfettii essential oil were hexadecanoic acid (11.1%), spathulenol (10.8%), longifolene (8.8%), germacrene D (8.4%), aromadendrene oxide (6.0%) and linoleic acid (5.3%). Based on our analysis of literature data from other Centaurea essential oils, they were positively correlated with antimicrobial activity. Using an agar disk diffusion method, tested chemical constituents did not show experimental evidence to support this positive correlation to antimicrobial activity when we tested them as pure components. The antibacterial effect of essential oil constituents may be related to a complex synergistic, rather than a single component as suggested by performed network pharmacology analysis, underlying the theoretical interactions between the essential oil phytochemicals listed as potentially responsible for antimicrobial activity and should be confirmed in further in-depth studies. This is the first report on the comparative analysis of Centaurea essential oils with good antimicrobial activity, as well as the first analysis of chemical components of the essential oil from C. triumfettii and the first report of antimicrobial activity of the representative, pure components: aromadendrene, germacrene D, spathulenol, longifolene, and the mixture of selected chemical compounds. This work contributes to the body of knowledge on the genus Centaurea and C. triumfettii species

First-order transition in the one-dimensional three-state Potts model with long-range interactions

The first-order phase transition in the three-state Potts model with long-range interactions decaying as $1/r^{1+\sigma}$ has been examined by numerical simulations using recently proposed Luijten-Bl\"ote algorithm. By applying scaling arguments to the interface free energy, the Binder's fourth-order cumulant, and the specific heat maximum, the change in the character of the transition through variation of parameter $\sigma$ was studied.Comment: 6 pages (containing 5 figures), to appear in Phys. Rev.