High-purity Samples Research Articles

Final results on neutrino oscillation parameters from the OPERA experiment in the CNGS beam

The OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. Exploiting the OPERA detector capabilities, it was possible to isolate high purity samples of $\nu_{e}$, $\nu_{\mu}$ and $\nu_{\tau}$ charged current weak neutrino interactions, as well as neutral current weak interactions. In this Letter, the full dataset is used for the first time to test the three-flavor neutrino oscillation model and to derive constraints on the existence of a light sterile neutrino within the framework of the $3+1$ neutrino model. For the first time, tau and electron neutrino appearance channels are jointly used to test the sterile neutrino hypothesis. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit values obtained by MiniBooNE combining neutrino and antineutrino data are excluded at 3.3 $\sigma$ significance.

X-ray spectroscopy with an AlInP photodiode

Abstract A custom-made Al 0.52 In 0.48 P p + -i-n + circular mesa X-ray photodiode ( 200 μ m diameter; 2 μ m i layer thickness) has been investigated for its use in photon counting X-ray spectroscopy within the energy range 4.95 keV to 21.17 keV. This is the widest energy range so far used to characterize an AlInP X-ray detector. High-purity X-ray fluorescence calibration samples were excited by a Mo target X-ray tube to give characteristic energy photons with which to illuminate the detector. X-ray fluorescence spectra were accumulated with the Al 0.52 In 0.48 P X-ray detector coupled to a custom-made charge-sensitive preamplifier (both operated at a temperature of 30 °C ± 2 °C). The charge output linearly increased with X-ray photon energy. The energy resolution (Full Width at Half Maximum, FWHM) degraded from 0.99 keV ± 0.02 keV (80 e − rms) at 4.95 keV to 1.12 keV ± 0.02 keV (89 e − rms) at 21.17 keV. The increase of the FWHM with increased energy exceeded the increase expected as a consequence of Fano noise. Hence, the presence of energy dependent incomplete charge collection noise was suggested. The count rate linearly increased with increasing incident X-ray flux across the investigated flux range, up to ∼ 3 . 8 × 105 photons s−1 cm−2.

Quantitative 1H NMR spectroscopy (qNMR) in the early process development of a new quorum sensing inhibitor

2-methyl-5,6,7,8-tetrahydro-2H-chromen-4(3H)-one (called 6-oxo) is presented as a new AI-1 quorum sensing inhibitor for Vibrio harveyi. The development of a chemical process to afford traceable materials for new biological assays demands the development of analytical methods to ensure their purity and quality. This work describes the use of quantitative 1 H nuclear magnetic resonance (NMR) spectroscopy (qNMR) to assess the purity of a sample of 6-oxo (99.88%) and a sample of its major process impurity (E)-1-(2-hydroxycyclohex-2-en-1-yl)but-2-en-1-one (called HCB; 98.28%). To explore the scope of the use of qNMR to quantify the amount of low-content components in samples related to the chemical process for 6-oxo synthesis, this work also determined the amount of 6-oxo in two HCB samples: (a) the high-purity HCB sample described above and (b) a crude HCB sample collected during the chemical process. Despite the complexity of the crude sample, the amount of 6-oxo was readily assessed and could help to estimate the extent to which 6-oxo was already formed during the HCB synthesis. This information can help the understanding of how the process parameters can be modified to improve the performance of the whole process, by controlling the reaction mechanisms working at each step of this chemical process. In this context, our results reinforce qNMR as a complementary analytical tool for the quantification of the main component found in a sample, contributing to the standardization of reference materials and thus allowing the development of analytical methods for process control and traceability of the samples used for biological assays.

Modelling the kinetics of chalcocite leaching in acidified cupric chloride media under fully controlled pH and potential

The use of seawater in heap leaching of secondary copper sulfide minerals is a feasible alternative to freshwater in regions with limited freshwater supply. Seawater contains high concentrations of chloride ions that facilitate the formation of cupric/cuprous chloride complexes. The cupric ions formed can serve as an oxidizing agent for chalcocite oxidation. Even though copper leaching in chloride media has been well studied, most of the kinetics data were collected under uncontrolled leaching conditions. In this study, we modelled chalcocite leaching kinetics in chloride media using leaching data collected under fully-controlled pH and solution potential. Specifically, we carried out leaching tests with high-purity chalcocite sample in jacketed reactors to quantify the effects of chloride concentration, cupric concentration, particle size, and temperature on the copper extraction rate. The experimental results show that increases in chloride concentration and temperature remarkably enhanced the leaching rate; chalcocite leaching was insensitive to the initial cupric chloride concentration. Using the leaching data collected, we derived two individual kinetic models to describe the first and second stage of chalcocite leaching. This study provides fundamental kinetic models for predicting the performance of chalcocite leaching in cupric chloride for heap leach operations that intend to use seawater.

Experimental designs for optimizing the purification of immunoglobulin G by mixed-mode chromatography

The main aim of this study was to define the optimal adsorption and elution conditions for the purification of human immunoglobulin G (IgG) by mixed-mode chromatography using the multimodal resin Capto MMC. To this end, Central Composite Experimental Design (ED) was performed for both the adsorption and desorption stages. In the first case, the conditions were systematically studied in batch mode while in the latter case, these were performed in column. For both studies, the experimental design was conducted using high-purity human IgG samples. Buffer pH and concentration as well as the salt concentration were the parameters under study in the ED. Adsorption kinetics and equilibrium experiments were performed under the best conditions defined in the ED (phosphate buffer 60 mmol/L, pH 6.75, no salt). The equilibrium experimental data were fit to the Langmuir equation, with maximum uptake qmax equal to 549.2 mg/g. The qmax value found for IgG in Capto MMC was quite high as compared to other chromatographic techniques that employ single modes of interaction. Regarding elution, the best conditions were obtained with acetate buffer (56.40 mmol/L), pH 5.2 and 0.2 mol/L NaCl. An ultimate recovery of 46.96% for high-purity IgG was achieved. Thus, the effectiveness of Capto MMC for IgG adsorption and recovery could be confirmed. Moreover, electrophoretic runs in the human serum indicated that although co-elution of HSA and IgG proteins occurs, substantial HSA removal and a high IgG recovery were achieved in the elution step.

Abstract 5099: Evaluation of two next-generation sequencing platforms for genomic analysis in circulating tumor cells

Abstract Background: Circulating tumor cells (CTCs) are released from primary or metastatic tumors into the cancer patient’s bloodstream and may establish secondary tumors in distant body sites. Their frequencies are thought to have great prognostic impact and their mutation signatures may yield pointers in treatment decisions. However, CTCs are extremely rare in the blood and are challenging to sequence. Current next-generation-sequencing (NGS) technologies and analysis procedures must be carefully strategized to maximize sensitivity, while maintaining specificity and controlling false discovery rates. Aim of the study: This study aims to establish a robust and sensitive NGS bench work and analysis pipeline for genetic analysis of CTCs with good positive predictive value (PPV) and low false discovery rate (FDR), which can ultimately be translated into clinical application. We will compare and evaluate the performance of two NGS platforms for CTC analysis in the Hong Kong cancer patients. Methods: This study will streamline the sequencing and analyses of two NGS approaches, i.e. amplicon-based or hybridization capture-based, for their application for CTC analyses. Firstly, a cancer cell line with known mutations will be spiked into normal blood cells at different percentages and sequenced with both approaches independently. The amplicon-based platform covers 60 cancer relevant and actionable genes, while the customized capture kit for the hybridization-based platform includes 245 cancer relevant genes curated in our group. Both platform’s sensitivity, specificity, PPV and FDR will be evaluated. Secondly, CTCs from several cancer types with high incidence in Asia will be enriched by size, enumerated for comparative analysis, and sequenced. Sequencing results will be used to refine the analysis pipelines for both platforms. Results of sequencing analyses, including potential druggable targets and prognostic markers identified, will be determined. Results: We successfully detected over 80% of known mutations at as low as 1.25% CTC purity, and with FDRs below 10% at 2.5% CTC purity by the hybridization-based method. We detected damaging missense, stopgain, or splicing mutations with the amplification-based platform in all 19 samples sequenced so far. More than 80% of blood samples from cancer patients had at least 5 CTCs detected. Preliminary comparison of the sequencing results of one high CTC purity sample showed that more than 50% of variants detected by this platform was also identified by hybridization-based sequencing. Conclusion: Our study sheds light on studying the genomic profiles of the rare CTCs for clinical application and identifying the potential actionable targets in Asian cancer patients. Acknowledgements: This study is supported by the HKU Platform Technology Fund and the Hong Kong Research Grants Council Area of Excellence grant AoE/M-06/08 to MLL. Citation Format: Chi Shan Candy Lam, Wei Dai, Josephine Mun Yee Ko, Maria Lung. Evaluation of two next-generation sequencing platforms for genomic analysis in circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5099.

Abstract 2291: Single cell capture and molecular analysis of live CTCs using integrated microwells and single cell aspirator

Abstract Resistance to targeted therapies can be caused by acquired genomic alterations in genes that code for the targeted protein. Circulating tumor cells (CTCs) provide an accessible source of tumor cells from diverse metastatic lesions from which to evaluate the frequency of genomic alterations that can be matched to distinct phenotypes, including therapeutic resistance. Successful analysis of the diversity of molecular mechanisms of therapeutic resistance requires isolation of live tumor cells for nucleic acid extraction. We have developed a semi-automated single cell aspirating platform to enrich and isolate live, rare cell populations for downstream molecular analysis. Using immortalized cell lines, we were able to enrich a target population of cells from a mixed population resulting a high purity sample (71.7-83.8%) to interrogate. Target cells were captured for nucleic acid extraction for downstream gene expression to validate enrichment. We demonstrate the ability to achieve high quality whole genome and transcriptome endpoints from low cell numbers in cell lines: the lower threshold for cellular input required to attain whole genome amplification (WGA) products reliable for downstream sequencing applications is now being validated. We also isolated CTCs from patient blood samples and showed phenotypic heterogeneity of EpCAM expression among individual CTCs. EpCAMhigh and EpCAMlow CTCs were detected, with a broad range of fluorescent intensities (141.2-5804.56 MFI). Using the phenotypic characterization of EpCAM expression, individual live CTCs were identified and captured for evaluation of their genomic heterogeneity. We have identified molecular heterogeneity in these cells that may reflect heterogeneity driving treatment resistance in CRPC. Early identification of treatment resistant clones may help develop intervention strategies that prolong the efficacy of molecular targeted therapies. Citation Format: Charlotte N. Stahlfeld, Jake J. Tokar, David Quigley, David Niles, Jamie M. Sperger, Felix Feng, Joshua M. Lang. Single cell capture and molecular analysis of live CTCs using integrated microwells and single cell aspirator [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2291.

Optically variable AGN in the three-year VST survey of the COSMOS field

Context. The analysis of the variability of active galactic nuclei (AGN) at different wavelengths and the study of possible correlations of different spectral windows are a current main field of inquiry. Optical variability has been largely used to identify AGN in multivisit surveys. The strength of a selection based on optical variability lies in the opportunity of analyzing data from surveys of large sky areas by ground-based telescopes. However, the effectiveness of optical variability selection with respect to other multiwavelength techniques has been poorly studied down to the depth that is expected from next-generation surveys. Aims. Here we present the results of our r-band analysis of a sample of 299 optically variable AGN candidates in the VST survey of the COSMOS field, counting 54 visits spread over three observing seasons spanning more than three years. This dataset is more than three times larger than the dataset presented in our previous analysis, and the observing baseline is about eight times longer. Methods. We push toward deeper magnitudes (r(AB) ∼ 23.5 mag) than were reached in past studies. We made wide use of ancillary multiwavelength catalogs in order to confirm the nature of our AGN candidates, and constrained the accuracy of the method based on spectroscopic and photometric diagnostics. We also performed tests aimed at assessing the relevance of dense sampling in view of future wide-field surveys. Results. We demonstrate that the method allows the selection of high-purity (> 86%) samples. We take advantage of the longer observing baseline to achieve great improvement in the completeness of our sample with respect to X-ray and spectroscopically confirmed samples of AGN (59% vs. ∼15% in our previous work), as well as in the completeness of unobscured and obscured AGN. The effectiveness of the method confirms the importance of developing future more refined techniques for the automated analysis of larger datasets.

Polaronic interacceptor hopping transport in intrinsically doped nickel oxide

In this work, we revisit the issue of the nature of electronic transport in nickel oxide (NiO) and show that the widely used model of free small polaron hopping, initially raised to characterize transport in high-purity samples, is not appropriate for modeling intrinsically doped NiO. Instead, we present extensive evidence, collected by means of temperature- and frequency-dependent measurements of the electrical conductivity $\sigma$, that the model of polaronic inter-acceptor hopping can be used to consistently explain the electronic conduction process. In this framework, holes are localized to acceptors (Ni vacancies), forming a strongly bound, polaron-like state. They can only move through the film by hopping to a neighboring, at least partially unoccupied, acceptor. This renders the spatial overlap between neighboring polaronic wave functions a highly critical parameter. The signature of this process is the occurrence of two temperature regions of the DC conductivity, separated by about half the Debye temperature $\theta_D/2 \approx 200 K$. For $T > \theta_D/2$, holes are transferred by phonon-assisted hopping over the potential barrier between two sites, whereas phonon-assisted tunneling through the barrier dominates below that temperature. We also show that the degree of structural and electronic disorder plays a vital role in determining the characteristics of the transport process: high disorder leads to strong energetic broadening of the acceptor states such that hopping to more distant sites may be favored over transfer to nearest neighbors (variable range hopping). The assumption of high binding energies of the charge carriers at VNi is in accordance with the recent paradigm shift regarding the understanding of the electronic structure of NiO: holes doped into NiO couple to Ni 3d spins, thereby occupying deep polaron-like states within the band gap (Zhang-Rice bound doublets).

(Invited) Controlling Nanotube-Nanotube Interactions in Carbon Nanotube Networks: Implications for Energy Transport and Harvesting

While the unique chemical and physical structure of semiconducting single-walled carbon nanotubes (s-SWCNTs) were identified decades ago, marking these nanoscale materials as promising candidates for constituents in a variety of optical and electronic applications, the ability to generate high-purity samples has hampered efforts to validate these expectations. The intervening years have played witness to a number of elegant enrichment strategies aimed at extracting tailored semiconducting SWCNT species from the raw soot, from the use of subtly tunable surfactant interactions to the exploitation of specific DNA sequences. In contrast, we employ an enrichment approach based on conjugated polymers, typically derived from the fluorene moiety, since they show great promise with regards to their high selectivity and viability for scalable manufacturing approaches.As alluded to above, these fluorene-based (co-)polymers confer solubility on the s-SWCNT species, allowing for the preparation of highly enriched s-SWCNT dispersions that can be deposited using a variety of solution-processing approaches. Unfortunately, the strong van de Waals forces between the π-electron systems of the polymer and SWCNT that enable the selective extraction of semiconducting SWCNTs with high purity also make removal of the polymer difficult. Since these polymers typically have a wide bandgap they can act as an insulating coating on the surface of the individual SWCNTs within functional networks, inhibiting the transport of energy in the form of excitons and/or charge carriers.Here we demonstrate approaches that allow us to replace the strongly-bound polymers with derivatives that can be removed using simple solution-based chemical strategies, resulting in networks with modified energy transport properties. We show that removal of the polymer results in a significant enhancement of the charge carrier mobility and electrical conductivity in doped s-SWCNT networks. Finally, we extend the approach to samples strongly enriched in a single chiral s-SWCNT species, which allows us to employ transient spectroscopic techniques to probe exciton transport within the s-SWCNT network with high spectral fidelity. We show that the efficiency of exciton transport is subtly dependent on the complex interplay between polymer removal and carbon nanotube bundling. Our studies highlight a methodology by which high-performance s-SWCNT thin films can be prepared and discuss the implications of our findings on the potential to realize their promise for electronic and optoelectronic applications.

Synthesis, properties and thermal decomposition of the Ta4AlC3 MAX phase

The present work describes a synthesis route for bulk Ta4AlC3 MAX phase ceramics with high phase purity. Pressure-assisted densification was achieved by both hot pressing and spark plasma sintering of Ta2H, Al and C powder mixtures in the 1200–1650 °C range. The phases present and microstructures were characterized as a function of the sintering temperature by X-ray diffraction and scanning electron microscopy. High-purity α-Ta4AlC3 was obtained by hot pressing at 1500 °C for 30 min at 30 MPa. The β-Ta4AlC3 allotrope was observed in the samples produced by SPS. The Young’s modulus, Vickers hardness, flexural strength and single-edge V-notch beam fracture toughness of the high-purity bulk sample were determined. The thermal decomposition of Ta4AlC3 into TaCx and Al vapour in high (˜10−5 mbar) vacuum at 1200 °C and 1250 °C was also investigated, as a possible processing route to produce porous TaCx components.

Separation of particles with bacterial size range using the control of sheath flow ratio in spiral microfluidic channel

A method of concentrating and separating small particles with a specific size in a microfluidic system can be applied to obtain high-purity biological samples, such as viruses, bacteria, and cells. This paper presents the highly efficient separation method of bacteria-sized particles using Dean flow and inertial force in a curved spiral microfluidic channel. By adjusting the flow rate ratio of particle solution to sheath flow at the inlet, the stream line of small particles circulating in the transverse direction with Dean flow becomes more distinct from large particle stream line focused at specific equilibrium position by inertial force. Therefore, submicron-sized particles can be separated from larger particles with high efficiency. In addition, the effects of the number of small particle circulations with Dean flow on the extraction efficiency have been studied. The fluidic channel has been tested for the separation of fluorescent particles with diameters of 0.81 μm, 2.29 μm, and 4.70 μm. The channel design and flow control were optimized so that 0.81-μm particles circulated in the channel along with Dean flow, while 2.29-μm and 4.70-μm particles were concentrated at separate equilibrium points by the inertial force. The extraction yields of 0.81-μm, 2.29-μm, and 4.70-μm particles were measured to be 98.42%, 97.69%, and 99.17%, respectively. Moreover, separation of bacteria from 2.29-μm and 4.70-μm particles has been demonstrated with 98.01% extraction yield.

Temperature-Induced on the Phase Formation and Its Microstructure of LiNiPO4/C Cathode Materials for Lithium-Ion Batteries

LiNiPO4 is one of the cathode Lithium-Ion Batteries (LiB) with olivine structure which has the potential to improve LiB performance, because highest operating voltage. The phase of olivine structure with high purity plays an important role in electrochemical properties of LiB. In this research, LiNiPO4 materials were synthesized with temperature sintering at 900 °C using solid-state reaction method to get high purity samples. Moreover, LiNiPO4 samples were coated with sucrose as a carbon source to increase of ionic conductivity. The samples were characterized by an investigation of phase and microstructure with X-ray Diffraction, X-Ray Fluorescence and Fourier Transform Infrared Spectroscopy.

Микроструктура и фазовые соотношения нанокристаллов кобальта, полученного интенсивной пластической деформацией

Nanostructured cobalt samples were obtained by method of severe plastic deformation by torsion. The high quasi-hydrostatic pressure in the working region (up to 8 GPa ) was created at installation of Bridgman anvil type. The anvils were made of tungsten carbide. he method allows to obtain the samples of high purity without pores and impurities. To carry out of X-ray studies, a DRON-7 diffractometer with cobalt radiation was used. X-ray analysis was performed according to the Bragg-Brentano method. For phase analysis the Kα lines were used. The sizes of nanocrystalline cobalt reached about 25 ¸ 50 nm. It is established that during low-temperature annealing a reset occurs in the structure of cobalt. Annealing above 3000C leads to recrystallization of its structure. Derived by severe plastic deformation by torsion nanocrystalline cobalt after heating above the phase transition temperature and cooling below this temperature retains the high-temperature fcc structure. It is shown that the nature of the hcp-fcc delayed transition can be connected with a sizes changes and a strained state of crystallites forming nanocrystalline cobalt.

Thermal Stability and Thermoelectric Properties of NaZnSb.

A layered Zintl antimonide NaZnSb (PbClF or Cu2Sb structure type; P4/nmm) was synthesized using the reactive sodium hydride NaH precursor. This method provides comprehensive compositional control and facilitates the fast preparation of high-purity samples in large quantities. NaZnSb is highly reactive to humidity/air and hydrolyzes to NaOH, ZnO, and Sb in aerobic conditions. On the other hand, NaZnSb is thermally stable up to 873 K in vacuum, as no structural changes were observed from high-temperature synchrotron powder X-ray diffraction data in the 300–873 K temperature range. The unit cell expansion upon heating is isotropic; however, interatomic distance elongation is not isotropic, consistent with the layered structure. Low- and high-temperature thermoelectric properties were measured on pellets densified by spark plasma sintering. The resistivity of NaZnSb ranges from 11 mΩ∙cm to 31 mΩ∙cm within the 2–676 K range, consistent with heavily doped semiconductor behavior, with a narrow band gap of 0.23 eV. NaZnSb has a large positive Seebeck coefficient (244 μV∙K−1 at 476 K), leading to the maximum of zT of 0.23 at 675 K. The measured thermoelectric properties are in good agreement with those predicted by theoretical calculations.

Transport mechanisms and property optimization of p-type (Zr, Hf)CoSb half-Heusler thermoelectric materials

Owing to the diverse sample quality as a result of different synthesis methods, previous studies on p-type MCoSb (M = Zr, Hf, Ti)-based half-Heusler thermoelectric (TE) compounds yield inconsistent results. It is thus necessary to verify the optimized carrier concentration and understand the transport mechanisms for this system based on high-purity samples, which can provide the guidance of further improving its TE properties and reasonably assess the application potential. In this work, high-purity Zr0.5Hf0.5CoSb1-xSnx (x = 0.05–0.30) and Zr1-yHfyCoSb0.8Sn0.2 (y = 0–1.0) are synthesized to understand the intrinsic electrical and thermal transport features. The optimized carrier concentration is found to be about 2.2×1021 cm−3 with the Sn doping level x = 0.2. A high power factor more than 3×10−3 Wm−1K−2 at 800 K is achieved for Zr0.5Hf0.5CoSb0.8Sn0.2. Moreover, our results indicate that it is necessary to combine alloying at the M site and grain refinement to achieve a low lattice thermal conductivity. A relatively high zT ∼0.93 at 1123 K is obtained for the Zr0.5Hf0.5CoSb0.8Sn0.2 sample. This work provides useful insight into the charge carrier and phonon transport mechanisms and confirms the TE application potential of this system.

Diamagnetism of Bulk Graphite Revised

Recently published structural analysis and galvanomagnetic studies of a large number of different bulk and mesoscopic graphite samples of high quality and purity reveal that the common picture assuming graphite samples as a semimetal with a homogeneous carrier density of conduction electrons is misleading. These new studies indicate that the main electrical conduction path occurs within 2D interfaces embedded in semiconducting Bernal and/or rhombohedral stacking regions. This new knowledge incites us to revise experimentally and theoretically the diamagnetism of graphite samples. We found that the c-axis susceptibility of highly pure oriented graphite samples is not really constant, but can vary several tens of percent for bulk samples with thickness t ≳ 30 μm, whereas by a much larger factor for samples with a smaller thickness. The observed decrease of the susceptibility with sample thickness qualitatively resembles the one reported for the electrical conductivity and indicates that the main part of the c-axis diamagnetic signal is not intrinsic to the ideal graphite structure, but it is due to the highly conducting 2D interfaces. The interpretation of the main diamagnetic signal of graphite agrees with the reported description of its galvanomagnetic properties and provides a hint to understand some magnetic peculiarities of thin graphite samples.

Dynamic reflectance changes in high-purity zirconium when it is shocked from the α to ω phase

Flash lamp-illuminated integrating spheres have been used to measure the dynamic reflectance at the interface between a shocked metal target and a window maintaining the shock stress. In conjunction with radiance measurements, this method was recently used to study the pressure versus temperature phase boundary of the beta phase to body-centered-tetragonal transition of tin at around 13 GPa and, in separate experiments, to show a relationship between the reflectance and the phase fraction. We have used this technique to measure the ratio, R, of the dynamic reflectance relative to the ambient value for a high-purity zirconium sample attached to a sapphire window to study the alpha to omega phase transition. Nine experiments cover the range of stress, σ, from 4 to 16 GPa at six wavelengths from 500 to 1550 nm. The two phases in zirconium differ in volume by <1%, so a phase change between them can be difficult to identify from anomalies in the particle velocity measured on the shock Hugoniot. The phase boundary is believed to cross the Hugoniot around 3 GPa, but dynamically it is observed at much higher stresses >6 GPa. Our results show that the relative reflectance decreases upon initial shock in the alpha state but increases as the material transforms to its omega state. The slope dR/dσ changes the sign around the phase transition. For shocks below 6 GPa, dR/dσ < 0, and for σ above 10 GPa, dR/dσ > 0. In the stress region between 6 and 10 GPa, dR/dσ varies somewhat, perhaps due to the band structure or because the transition is incomplete there.

Protein structural biology using cell-free platform from wheat germ

One of the biggest bottlenecks for structural analysis of proteins remains the creation of high-yield and high-purity samples of the target protein. Cell-free protein synthesis technologies are powerful and customizable platforms for obtaining functional proteins of interest in short timeframes, while avoiding potential toxicity issues and permitting high-throughput screening. These methods have benefited many areas of genomic and proteomics research, therapeutics, vaccine development and protein chip constructions. In this work, we demonstrate a versatile and multiscale eukaryotic wheat germ cell-free protein expression pipeline to generate functional proteins of different sizes from multiple host organism and DNA source origins. We also report on a robust purification procedure, which can produce highly pure (> 98%) proteins with no specialized equipment required and minimal time invested. This pipeline successfully produced and analyzed proteins in all three major geometry formats used for structural biology including single particle analysis with electron microscopy, and both two-dimensional and three-dimensional protein crystallography. The flexibility of the wheat germ system in combination with the multiscale pipeline described here provides a new workflow for rapid production and purification of samples that may not be amenable to other recombinant approaches for structural characterization.

Carbothermal reduction of oxidized tin and recovery of deep supercool

Deep supercooling of tin is a characteristic sign of a high-purity sample having fewer nucleation sites. However, due to the risk of oxidation during the cell fabrication (especially during the initial sample filling process), oxidized tin can be present in the sample, which manifests itself as a nucleation agent and significantly affects the realization of the freezing temperature of tin. In this work, the effect of the oxidation of high-purity tin (nominally 99.9999% pure) and an effective means of reducing the oxidized sample were investigated. We fabricated an open-type tin freezing point cell using 1.15 kg of high purity tin shot, which was poured into the crucible in air, giving rise to a high risk of oxidation. The oxidized tin sample showed abnormally small supercools of about 0.1 °C which were caused by additional nucleation sites introduced by the oxidation. The oxidized sample also exhibited a melting temperature inversion over the entire range of the melting with a temperature depression of about 1.9 mK. The oxidized sample was carbothermally reduced by melting the sample in its graphite crucible and holding at a temperature of 750 °C for a total duration of 365 h. The carbothermal reduction of the oxidized sample caused the satisfactory recovery of the deep supercool, and the recovered supercool was about 10.6 °C after about 100 h of reduction, and 10.7 °C after 365 h of reduction. At the end of the reduction process, the melting curve inversion was significantly alleviated, having 0.1 mK temperature depression over less than 10% of the melting range. Importantly, the carbothermal reduction at 750 °C was found to be an effective means of removing the oxide nucleation sites and of recovering the characteristic deep supercool of tin.