3D Spectra Research Articles

Observation and identification of autofluorescent urine crystals may be linked to a sign of urolithiasis.

Urolithiasis is a common disease of the urinary system. Its recurrence rate is high and may increase medical expenses. Urine stones are composed of urine crystals and other impurities. We discovered the existence of autofluorescence in some of the urine crystals, especially in urolithiasis patients. The fluorescent molecule existed in urine crystals was verified and identified. We have applied micro-Raman and fluorescence microscopy to classify the urine crystals, used confocal laser scanning microscopy (CLSM) to examine the 3D images and spectra of autofluorescence in crystals, used Fourier-transform infrared spectroscopy (FTIR) and mass spectrometry (MS) to identify the type of fluorophore in the autofluorescent urine crystals in urine. Riboflavin was identified as one of the major fluorophores in these autofluorescent urine crystals. The prevalence rates of the autofluorescent crystals in urolithiasis patients and subjects without the history of urolithiasis were to gather statistics. We observed that 80% of urolithiasis patients had autofluorescent crystals. Contrastingly, such crystals existed in only 7% of subjects without the history of urolithiasis. The presence of autofluorescent urine crystals may be linked to a sign of urolithiasis.

Hydrogen sulfite promoted the activation of persulfate by μM Fe2+ for bisphenol A degradation.

This study evaluated the improvement of bisphenol A (BPA) elimination through hydrogen sulfite (HS) coupling with persulfate (PS) activated by low amounts of Fe2+. Under the optimum condition (10μM Fe2+, 0.6mM HS, 0.8mM PS, pH = 4.0), 100% BPA (5μM) was removed within 15min. Sulfate radical (SO4•-) and singlet oxygen (1O2) were confirmed as the primary active species for BPA degradation in the Fe2+/HS/PS system, and the steady-state concentration of SO4•- and 1O2 was 2.43 × 10-9M and 1.67 × 10-9M, respectively. Besides, FeHSO3+ and FeOHSO3H+ were the main iron species in the Fe2+/HS/PS system. The removal potency of BPA depended on the operation parameters, such as chemical reagent dosages, reaction temperature, and the solution initial pH. The impact of NO3-, SO42-, and humic acid (HA) on BPA removal was negligible, whereas Cl-, HCO3-, and HPO42- restrained BPA decomposition. Two injections of HS could improve the limitation of BPA degradation efficiency due to the rapid consumption of HS in the reaction process. The lower removal efficiency of BPA was observed in real water matrices than that in ultrapure water. Whatever, up to 58.1%, 66.3%, 68.1%, and 88.1% of BPA were removed from domestic wastewater, lake water, river water, and tap water within 10min, respectively. In addition, the BPA degradation process was characterized by the 3D fluorescence spectra technique, which indicated the BPA oxidation intermediates also have fluorescence characteristics. Moreover, 6 intermediate products were identified, and the possible degradation pathways of BPA were proposed. Additionally, the Fe2+/HS/PS system also exerted an excellent performance for the removal of other representative organic contaminants including enrofloxacin, acid orange 7, acetaminophen, and phenol. All results indicated that the Fe2+/HS/PS system could be a promising method for organic pollutant removal.

Texture, microstructure and mechanical properties of laser beam welded AISI 2507 super duplex stainless steel

This study investigates weldability of AISI 2507 super duplex stainless steel (SDSS) sheets with laser welding. The impact of heat inputs and post-weld heat treatment (PWHT) on the mechanical properties, texture, microstructure and the surface of joints were analyzed. The microhardness and tensile strength values of the samples welded with the lowest weld heat input was detected to be greater than samples welded with the high heat input. The highest values for tensile strength, bending force and impact toughness in welded samples have been identified as 891 MPa, 1092 N and 58.4 J respectively. The effect of PWHT caused a decrease in the hardness and tensile strength of all samples, and improved the toughness and ductility properties. While dislocations and stacking faults were observed in the base material microstructure, twinning formation was also detected in the weld metal. Secondary austenite (γ2) and Cr23C6 carbides were also found after heat treatment. Variations in the coincidence site lattice (CSL) boundary proportions and the Schmid factors (SFs) directly affected the mechanical properties. In the 2D- and 3D-orientation distribution function (ODF) base material and weld metal maps, the δ-ferrite and γ-austenite textures performed high-density γ-fiber and α-fiber orientations and a low-density (110) <110> rotated cube component, and showed high-density γ-fiber and low-density α-fiber RD//<110> orientations after heat treatment. When the orientation relationships of the heat-treated sample were examined, Kurdjumov–Sachs (K–S) and Nishiyama–Wassermann (N–W) relationships were determined between the γ/α phases in the base material and weld metal, in addition to these orientation relationships, a occasionally seen (100)γ//(100)α Bain orientation relationship was also found in the non-heat-treated sample. The atomic concentrations of the non-heat-treated and heat-treated weld metals exhibited an increase in the O1s spectrum and decreases in the Ni 2p, Fe 2p, Mo 3d and Cr 2p spectra with increasing sputtering time. Diffusion of H− ion with low density to ferrite and austenite grains on weld metal structure was observed.

FLUORESCENCE STUDIES ON THE BLOOD PLASMA ALBUMIN INTERACTION WITH 4-HYDROXY-2-METHYLQUINOLINE

Blood plasma albumin (bovine serum albumin, BSA) interaction with a biologically active reagent 4-hydroxy-2-methylquinoline (4H2MQ) has been studied using fluorescence spectroscopy methods (steady state, synchronous, excitation/emission matrix, 3D spectra). With the addition of 4H2MQ, no changes in the spectral characteristics of BSA (fluorescence emission intensity and λmax position) are observed; only the symmetry of the BSA emission spectrum is changed and the full width at half maximum is decreased. The analysis of synchronous and 3D fluorescence spectra showed the existence of three emitting species in this system, which could be a result of changes in the fluorescence and photochemical properties of 4H2MQ.

Photocatalytic Decomposition of an Azo Dye Using Transition-Metal-Doped Tungsten and Molybdenum Carbides.

The preparation, characterization, and photocatalytic application of tungsten or molybdenum carbides (Ni-WC, 1, Co-WC, 2, Ni-MoC, 3, Co-MoC, 4, NiCo-WC, 5, NiCo-MoC, 6, NiFe-WC, 7, and NiFe-MoC, 8) doped with transition metals (Fe, Co, and Ni) are reported. These transition-metal carbide (TMC) particles show that the submicrometer globular particles agglomerated to form larger particles, with smaller crystallites present on the surface of the large particles. These crystallite sizes range between 4 and 34 nm (as calculated from X-ray diffraction data) depending on the metal dopant and type of carbide. Oxidation of the metal carbides is evident from the two sets of photoelectron lines present in the X-ray photoelectron spectroscopy (XPS) of the W 4f area. The Mo 3d spectra reveal four sets of photoelectron lines associated with oxidized MoO2 and MoO3 as well as Mo2+ and Mo3+ associated with MoC1–x. The XPS of the dopant metals Ni, Co, and Fe also show partial oxidation. The photocatalytic decomposition of Congo red (an azo dye) is used as a model reaction to determine the photocatalytic activities of the transition-metal carbides, which is related to the TMCs’ optical band gap energies.

Deep Learning-Based Sensor Array: 3D Fluorescence Spectra of Gold Nanoclusters for Qualitative and Quantitative Analysis of Vitamin B6 Derivatives.

Vitamin B6 derivatives (VB6Ds) are of great importance for all living organisms to complete their physiological processes. However, their excess in the body can cause serious problems. What is more, the qualitative and quantitative analysis of different VB6Ds may present significant challenges due to the high similarity of their chemical structures. Also, the transfer of deep learning model from one task to a similar task needs to be present more in the fluorescence-based biosensor. Therefore, to address these problems, two deep learning models based on the intrinsic fingerprint of 3D fluorescence spectra have been developed to identify five VB6Ds. The accuracy ranges of a deep neural network (DNN) and a convolutional neural network (CNN) were 94.44-97.77% and 97.77-100%, respectively. After that, the developed models were transferred for quantitative analysis of the selected VB6Ds at a broad concentration range (1-100 μM). The determination coefficient (R2) values of the test set for DNN and CNN were 93.28 and 97.01%, respectively, which also represents the outperformance of CNN over DNN. Therefore, our approach opens new avenues for qualitative and quantitative sensing of small molecules, which will enrich fields related to deep learning, analytical chemistry, and especially sensor array chemistry.

High zirconium loads in Zr-SBA-15 mesoporous materials prepared by direct-synthesis and pH-adjusting approaches

SBA-15 is a material with interesting characteristics associated with the size, order, uniformity, and pores distribution. However, the absence of acidity in SBA-15 restricts its applications as a potential acid catalyst in the industry for the large-scale production of fuels and chemicals. Mesoporous SBA-15 modified by the incorporation of heteroatomic species can be a good strategy to include acidity and prepare an efficient catalyst. In this work, we present a comparative study in the preparation of SBA-15 and Zr-SBA-15 mesoporous materials with high zirconium loads (Si/Zr ​= ​10, 5, and 2) using direct-synthesis and pH-adjusting approaches with a low crystallization temperature of 60 ​°C. The materials were characterized using XRPD, HRTEM, ICP, SEM-EDS, XPS, DRS UV-VIS, FT-IR, NH3-TPD, in situ FT-IR with pyridine probe, and N2-physisorption. Characterization by ICP and SEM-EDS indicated that the Si/Zr molar ratio of Zr-materials prepared by the pH adjustment better matched the nominal values. N2-physisorption showed that the mesoporosity of the materials was preserved even at the high Zr load. XRPD and HRTEM pointed out that Zr-SBA-15 materials prepared by the pH adjustment showed a higher level of ordering in the porous network. Regardless of the synthesis approach, the presence of a higher Zr load caused a loss in the structural ordering. It must be highlighted that the high-resolution XPS spectra of Zr 3d suggested the formation of Si–O–Zr bonds giving some indication of Zr incorporation into the SBA-15 framework. The formation of Si–O–Zr linkage in the Zr-materials was also corroborated by DRS UV-VIS due to the presence of a blue shift in the absorption edge for both series of the Zr-SBA-15 materials. NH3-TPD and in-situ FT-IR spectroscopy with pyridine probe showed that the presence of Zr species introduces acidity in the SBA-15 and at higher Zr load the Brønsted acidity increased particularly for the Zr-materials prepared by pH adjustment. In conclusion, this study evidences that the pH-adjusting approach improves structural, textural, morphological, and acidic properties in SBA-15 and Zr-SBA-15 materials compared to the direct-synthesis approach.

Interpolation of spectra from 3D model atmospheres

Context. The use of 3D hydrodynamical simulations of stellar surface convection for model atmospheres is computationally expensive. Although these models have been available for quite some time, their use is limited because of the lack of extensive grids of simulations and associated spectra. Aims. Our goal is to provide a method to interpolate spectra that can be applied to both 1D and 3D models, and implement it in a code available to the community. This tool will enable the routine use of 3D model atmospheres in the analysis of stellar spectra. Methods. We have developed a code that makes use of radial basis functions to interpolate the spectra included in the CIFIST grid of 84 three-dimensional model atmospheres. Spectral synthesis on the hydrodynamical simulations was previously performed with the code ASSϵT. Results. We make a tool for the interpolation of 3D spectra available to the community. The code provides interpolated spectra and interpolation errors for a given wavelength interval, and a combination of effective temperature, surface gravity, and metallicity. In addition, it optionally provides graphical representations of the RMS and mean ratio between 1D and 3D spectra, and maps of the errors in the interpolated spectra across the parameter space.

The Negative Photoconductivity of Ag/AgO Grown by Spray-Pyrolysis

The main goal of this work is to provide a general description of the negative photoconductivity effect observed in Ag/AgO films grown by the spray-pyrolysis technique. X-ray diffractograms display hybrid films with high texturized AgO and metallic Ag phases. Scanning electron microscopy images show small Ag particles on the surface. Due to its surface nature, X-ray photoelectron spectroscopy revealed the predominance of the metallic character of Ag 3d spectra as compared to Ag2+. Negative photoconductivity with photoresponse in the order of seconds is observed under several wavelengths of excitation. We found that the amplitude of the negative photoresponse is strongly dependent on the optical absorbance and enhanced by surface plasmon resonance. The low-cost technique employed and the special features regarding negative photoconductivity provide an exciting platform for developing optical-electronic devices with low power consumption.

Effect of heat input and post-weld heat treatment on surface, texture, microstructure, and mechanical properties of dissimilar laser beam welded AISI 2507 super duplex to AISI 904L super austenitic stainless steels

In this study, AISI 2507 super duplex and AISI 904L super austenitic stainless steel sheets were successfully joined using a laser welding method with two different laser powers and laser speeds. The effects of different welding heat inputs and post-weld heat treatment on the surface, texture, microstructure and mechanical properties of laser welded joints were investigated. The results obtained in this study showed that the weld metal microstructure predominantly composed of austenite phase. In addition, the occurrence of γ-austenite (dendritic), interdendritic, ferrite, and planar, coplanar, and stacking fault was observed and also Cr23C6 precipitate was formed in the microstructure with the effect of heat treatment. In the sample joined with low heat input, an increase was observed in tensile strength, yield strength and hardness compared to the samples joined using high heat input, and a decrease in impact toughness occurred. With the effect of heat treatment, a decrease was observed in tensile, yield strength and hardness and an increase was observed in ductility and toughness. In addition, there was no significant change in the bending forces of all laser-welded samples, and the bending occurred on the super austenitic stainless steel side. While the austenite grains exhibited random orientation in the non-heat-treated and heat-treated AISI 2507 base metal and weld metal, the non-heat-treated and heat-treated AISI 904L base metal showed an orientation in the [101] and [111] directions in the transverse direction, respectively. The change in the ratio of the Schmid factor and coincidence site lattice (CSL) boundaries has a significant effect on the mechanical properties. In addition, since the kernel average misorientation (KAM) values in the interdendritic, ferrite grains and grain boundaries were higher than the austenite grains, the residual stresses were found to be higher. When the γ-austenite (dendritic), interdendritic and δ-ferrite textures were examined in the 3D-orientation distribution function maps of the non-heat-treated and heat-treated base metal and weld metal, γ-fibre and α-fibre orientations were observed at high density, and recrystallisation component (112) 〈111〉 at high density and component (113)〈332〉 with high toughness at high density appeared. The γ-austenite grains in the base metal and weld metal of the non-heat-treated and heat-treated samples showed a closer Kurdjumov–Sachs (KS) orientation relationship (OR) compared to the interdendritic and δ-ferrite grains. In the γ/δ and γ/interdendritic ORs, KS OR was generally observed, while Bain OR was observed in the heat-treated super duplex base metal. ORs known in the literature were not observed in the non-heat-treated weld metal. Densities observed in the non-heat-treated and heat-treated weld metal showed that as the sputtering time increased, the O1s spectrum decreased, and the Fe 2p, Cr 2p, Ni 2p and Mo 3d spectra increased.

Effect of illumination and applied potential on the electrochemical impedance spectra in triple cation (FA/MA/Cs) 3D and 2D/3D perovskite solar cells

Even though there has been numerous works performed based on electrochemical impedance spectroscopy (EIS) of perovskite solar cells (PSCs), however, many aspects of the obtained EI spectra are yet to be fully grasped. Moreover, the change of these spectra over the passage of time needs to be fully analysed and understood, therefore, this research aimed to perform a comparative study to provide a comprehensive understanding of the illumination and voltage dependence of impedence spectra of 3D & 2D/3D PSCs with aging time. The analysis was performed over the period of 5000 h of exposure of the PSCs to the ambient environment at room temperature (24 ± 1 °C). Complex EIS curves (nyquist plots and bode plots) have been investigated (with aging) in the dark, under 1 Sun illumination and at different applied potentials. Over the course of time, the charge transfer resistance (Rct) trend of both solar cells types was observed to be behaving oppositely in the dark and under illumination in the short circuit condition. Moreover, at high potentials in dark conditions, a negative capacitance feature was observed, while under 1 Sun illumination, this feature was realized even at low potentials. All of these complex observations have been interpreted and explained in terms of the charge dynamic in bulk and at the interfaces of 3D and 2D/3D PSCs. This study paves the way to understand further the complex charge dynamic processes within PSCs that evolve under different operating conditions with aging.

Impact of Tetrabutylammonium on the Oxidation of Bromide by Ozone.

The reaction of ozone with sea-salt derived bromide is relevant for marine boundary layer atmospheric chemistry. The oxidation of bromide by ozone is enhanced at aqueous interfaces. Ocean surface water and sea spray aerosol are enriched in organic compounds, which may also have a significant effect on this reaction at the interface. Here, we assess the surface propensity of cationic tetrabutylammonium at the aqueous liquid–vapor interface by liquid microjet X-ray photoelectron spectroscopy (XPS) and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The results clearly indicate that the positively charged nitrogen group in tetrabutylammonium (TBA), along with its surface activity, leads to an enhanced interfacial concentration of both bromide and the bromide ozonide reaction intermediate. In parallel, off-line kinetic experiments for the same system demonstrate a strongly enhanced ozone loss rate in the presence of TBA, which is attributed to an enhanced surface reaction rate. We used liquid jet XPS to obtain detailed chemical composition information from the aqueous-solution–vapor interface of mixed aqueous solutions containing bromide or bromide and chloride with and without TBA surfactant. Core level spectra of Br 3d, C 1s, Cl 2p, N 1s, and O 1s were used for this comparison. A model was developed to account for the attenuation of photoelectrons by the carbon-rich layer established by the TBA surfactant. We observed that the interfacial density of bromide is increased by an order of magnitude in solutions with TBA. The salting-out of TBA in the presence of 0.55 M sodium chloride is apparent. The increased interfacial bromide density can be rationalized by the association constants for bromide and chloride to form ion-pairs with TBA. Still, the interfacial reactivity is not increasing simply proportionally with the increasing interfacial bromide concentration in response to the presence of TBA. The steady state concentration of the bromide ozonide intermediate increases by a smaller degree, and the lifetime of the intermediate is 1 order of magnitude longer in the presence of TBA. Thus, the influence of cationic surfactants on the reactivity of bromide depends on the details of the complex environment at the interface.

Assessment of Physicochemical Groundwater Quality and Hydrogeochemical Processes in an Area near a Municipal Landfill Site: A Case Study of the Toluca Valley.

Sanitary landfills are considered one of the main sources of contamination of water resources due to the generation of leachate with a high content of dissolved organic matter (DOM), inorganic material, and toxic elements. This study aimed to determine the influence of leachate on the physicochemical quality and hydrogeochemical processes which determine the chemical composition of groundwater in an area near a municipal sanitary landfill site. In situ parameters (pH, temperature, electrical conductivity, dissolved oxygen, ORP), physicochemical parameters (HCO3−, PO43−, Cl−, NO3−, SO42−, NH4+, Ca2+, Mg2+, Na+, K+), and dissolved organic matter were analyzed. The content of dissolved organic matter (DOM) was determined by 3D fluorescence microscopy. The presence of Cl−, NO3−, NH4+, PO43−, BOD, and COD indicated the presence of contamination. The significant correlation between NO3− and PO43− ions (r = 0.940) and DOM of anthropogenic origin in the 3D fluorescence spectra confirm that its presence in the water is associated with the municipal landfill site in question. The type of water in the area is Mg-HCO3, with a tendency to Na-HCO3 and Na-SO+-Cl. The water-rock interaction process predominates in the chemical composition of water; however, significant correlations between Na+ and Ca2+ (r = 0.876), and between K+ and Mg2+ (r = 0.980) showed that an ion exchange process had taken place. Likewise, there is enrichment by HCO3− and SO42− ions due to the mineralization of the organic matter from the leachate. The groundwater quality that supplies the study area is being affected by leachate infiltration from the sanitary landfill.

Effect of Reducing and Oxidizing Atmosphere on Photoluminescence of Undoped, Eu Doped and Dy Doped Nanostructured CaAl2O4

Monocalcium aluminate (CaAl2O4) doped with Eu2+ is a phosphor that produces phosphorescence in the blue light (440 nm). It has attracting a great deal of attention because of its wide applications in energy-efficient illumination systems and information displays. CaAl2O4 codoped with Eu2+ and Dy3+ exhibits a very strong and long lasting persistence luminescence that could have many applications in the fields of emergency lighting signs, night-vision signage, in vivo bioimaging, dosimetry and optical data storage.In this work, we present the effect of the thermal treatment in the reducing (nitrogen) and oxidizing (air) atmosphere on the photoluminescence (PL) properties of nanostructured undoped CaAl2O4, CaAl2O4:Eu and CaAl2O4:Dy synthesized by the combustion method. The synthesized powders were characterized by XRD, SEM-EDS, FTIR and Raman techniques. The XRD analysis revealed that the powder mainly consists of krotite (CaAl2O4) together with a small amount of grossite (CaAl4O7) and mayenite (C12Al14O33).The 3D excitation-emission spectra of undoped and untreated CaAl2O4 exhibits a broad band with excitation/emission maximum at 338/412 nm, respectively. The thermal treatment slightly shift the position of the maximum for both the reducing and oxidizing atmosphere. It is interesting to note that the emission peak is red-shifted as the excitation wavelength red-shifts in the untreated sample while the emission peak positions are independent of the excitation wavelength in both reduced and oxidized samples. It is interesting to note that the emission peak shifts to red as the excitation wavelength shifts to red in the untreated sample, while the emission peak positions are independent of the excitation wavelength in reducing or oxidizing samples.The Eu doped sample treated in the oxidizing atmosphere exhibit the typical Eu3+ emission sharp bands while the reduced Eu doped sample reveals only broad Eu2+ emission band that partially overlaps with the band observed in undoped samples. The Dy doped samples exhibit the typical Dy3+ emission sharp bands regardless of their reducing or oxidizing thermal treatment.

Evaluation of Chemical Bonding States in Multilayer Interconnect Structures for Thermal Management in Next Generation Very Large Scale Integration

1. Background and purpose Currently, it is expected that Ru is going to be introduced in place of Cu, which is the mainstream interconnect material in the very large scale integrated (VLSI) circuit. As high integration has been proceeding, the interconnect is expected not only having excellent electrical characteristics and reliability, but also providing an effective pathway for the removal of the heat generated by device operation [1]. The increasing current density in the narrowing interconnect produces Joule heat. The generated heat is removed by a heat sink attached to the substrate through the interconnect. Therefore, if the thermal resistance between the substrate and the interconnect is high, the heat cannot be removed efficiently and the interconnect temperature rises, lead to a degradation of VLSI reliability [2].In this study, we evaluated chemical bonding states of Ru/TaN/(SiOx/)Si stacking structure to clarify the mechanism contributing thermal resistance for the superior thermal management in VLSI. 2. Experimental method A 5 nm TaN was deposited by reactive sputtering (Deposition conditions: 25°C, 300 W, 1.0×10-5 Pa, Ta target) and subsequently 10 nm Ru was deposited by magnetron sputtering on a Si substrate with approximately 2 nm-thick native oxide. We prepared four samples with Ar:N2 gas ratios of 19:1, 17:3, 16:4, and 15:5, respectively, during the TaN deposition. The total thermal resistance was measured by the Frequency Domain Thermoreflectance (FDTR) method under vacuum condition.We also evaluated the chemical bonding states at the interface by Laboratory Hard X-ray Photoelectron Spectroscopy (Lab. HAXPES). The measurement conditions were kinetic energy of 9.25 keV, energy resolution of 0.5 eV, energy step of 50 meV, beam diameter of 50 μm2, and detectable depth of 50 nm, respectively. Au 4f was used as a reference of the energy calibration during for the analysis. 3. Results and Discussion The thermal resistance measured from the entire Ru/TaN/(SiOx/)Si stacking structure was reported by previous studies [1]. It can be seen that the thermal resistance decreases with the increase of N2 flow rate. In order to discuss the mechanism for determination of the thermal conductance, we performed nondestructive measurements by Lab. HAXPES.Figures 1 and 2 show the photoelectron spectra obtained from Ru 3d (Ar:N2=19:1, 15:5) and Si 1s (Ar:N2=19:1, 15:5), respectively. From Fig. 1, no significant change is observed in Ru 3d spectra even within the N2 gas flow rate changes. Therefore, the cause of the change in thermal resistance with the N2 gas flow rate change cannot be found at the Ru/TaN interface. On the other hand, from the Si 1s spectrum shown in Fig. 2, it can be confirmed that the peak intensity due to Si-N or Si-O-N bonds increases with increasing N2 gas flow rate. Therefore, it can be considered that the Si-N or Si-O-N bonds formed at the TaN/(SiOx/)Si interface as the N2 gas flow rate increased promoted heat transport and contributed to the reduction of thermal resistance.In summary, the important mechanism to control the thermal resistance became clear by the non-destructive evaluation of the chemical bonding states in the multilayer stacking structure using Lab. HAXPES. Acknowledgement This work was supported by the CREST under Project No. JPMJCR19Q5 of the Japan Science and Technology Corporation (JST).

Electron spin resonance of the itinerant ferromagnets LaCrGe3, CeCrGe3 and PrCrGe3

We report electron spin resonance of the itinerant ferromagnets LaCrGe3, CeCrGe3, and PrCrGe3. These compounds show well defined and very similar spectra of itinerant Cr 3d spins in the paramagnetic temperature region. Upon cooling and crossing the Cr-ferromagnetic ordering (below around 90 K) strong spectral structures start to dominate the resonance spectra in a quite different manner in the three compounds. In the Ce- and Pr-compounds the resonance is only visible in the paramagnetic region whereas in the La-compound the resonance can be followed far below the ferromagnetic ordering temperature. This behavior will be discussed in terms of the specific interplay between the 4f and 3d magnetism which appears quite remarkable since CeCrGe3 displays heavy fermion behavior even in the magnetically ordered state.

Nightshift: A Python program for plotting simulated NMR spectra from assigned chemical shifts from the Biological Magnetic Resonance Data Bank.

Nuclear magnetic resonance (NMR) provides site specific information on local environments through chemical shifts. NMR is widely used in the study of proteins, ranging from determination of three-dimensional (3D) structures to characterizing dynamics and binding of small molecules and other proteins or ligands. Assigned chemical shift data for the atoms within proteins is a treasure trove of information that can facilitate a broad range of biochemical and biophysical studies. The Biological Magnetic Resonance Data Bank (BMRB) is a publicly accessible database that contains a large number of assigned chemical shifts; however, translating this wealth of knowledge into a practical application is not straightforward. Herein we present nightshift: a Python command line utility and library for plotting simulated two-dimensional (2D) and 3D NMR spectra from assigned chemical shifts in the BMRB. This tool allows users to simulate routinely collected amide and methyl fingerprint spectra, backbone triple-resonance assignment spectra, and user-defined custom correlations, including ones that do not necessarily correspond to published experiments. This tool enables experienced NMR spectroscopists, those learning the craft, and interested scientists seeking to utilize NMR the ability to preview or examine a wide range of spectra for proteins whose assignments are deposited in the BMRB, irrespective of whether those experiments have been executed or reported. The tool applies equally to folded and intrinsically disordered proteins, limited only by the existence of a BMRB deposition. The features of nightshift are described along with applications that illustrate the ease with which complicated correlation spectra and binding events can be simulated.

1T′-MoTe2 and 2H-MoTe2 by XPS

Two different phases of the transition-metal dichalcogenide and molybdenum ditelluride (1T′-MoTe2 and 2H-MoTe2) were grown by chemical vapor transport. Oxygen-free surfaces were generated by exfoliation in air and then analyzed by x-ray photoelectron spectroscopy. High-resolution core and valence and Auger spectra were acquired for both materials including Te 3d, Te 4d, Te MNN, Mo 3d, and valence band spectra. Differences in Te 3d and Mo 3d peak positions that were previously reported were confirmed, and asymmetry on the metallic 1T′-phase was documented in the Te 3d, Te 4d, and Mo 3d spectra that could prove useful in identifying mixtures of these materials.

Minimizing Pervasive Artifacts in 4D Covariance Maps for Protein Side Chain NMR Assignments.

Nuclear magnetic resonance (NMR) is a mainstay of biophysical studies that provides atomic level readouts to formulate molecular mechanisms. Side chains are particularly important to derive mechanisms involving proteins as they carry functional groups, but NMR studies of side chains are often limited by challenges in assigning their signals. Here, we designed a novel computational method that combines spectral derivatives and matrix square-rooting to produce reliable 4D covariance maps from routinely acquired 3D spectra and facilitates side chain resonance assignments. Thus, we generate two 4D maps from 3D-HcccoNH and 3D-HCcH-TOCSY spectra that each help overcome signal overlap or sensitivity losses. These 4D maps feature HC-HSQCs of individual side chains that can be paired to assigned backbone amide resonances of individual aliphatic signals, and both are obtained from a single modified covariance calculation. Further, we present 4D maps produced using conventional triple resonance experiments to easily assign asparagine side chain amide resonances. The 4D covariance maps encapsulate the lengthy manual pattern recognition used in traditional assignment methods and distill the information as correlations that can be easily visualized. We showcase the utility of the 4D covariance maps with a 10 kDa peptidyl carrier protein and a 52 kDa cyclization domain from a nonribosomal peptide synthetase.

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions