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Every year, there are approximately 500 000 peripheral nerve injury (PNI) procedures due to trauma in the US alone. Autologous and acellular nerve grafts are among current clinical repair options; however, they are limited largely by the high costs associated with donor nerve tissue harvesting and implant processing, respectively. Therefore, there is a clinical need for an off-the-shelf nerve graft that can recapitulate the native microenvironment of the nerve. In our previous work, we created a hydrogel scaffold that incorporates mechanical and biological cues that mimic the peripheral nerve microenvironment using chemically modified hyaluronic acid (HA). However, with our previous work, the degradation profile and cell adhesivity was not ideal for tissue regeneration, in particular, peripheral nerve regeneration. To improve our previous hydrogel, HA was conjugated with fibrinogen using Michael-addition to assist in cell adhesion and hydrogel degradability. The addition of the fibrinogen linker was found to contribute to faster scaffold degradation via active enzymatic breakdown, compared to HA alone. Additionally, cell count and metabolic activity was significantly higher on HA conjugated fibrinogen compared previous hydrogel formulations. This manuscript discusses the various techniques deployed to characterize our new modified HA fibrinogen chemistry physically, mechanically, and biologically. This work addresses the aforementioned concerns by incorporating controllable degradability and increased cell adhesivity while maintaining incorporation of hyaluronic acid, paving the pathway for use in a variety of applications as a multi-purpose tissue engineering platform. [ABSTRACT FROM AUTHOR]

The advent of double-Wien filter-selection-aperture and hexapole-collision-cell technologies coupled to laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS/MS) enables in situ analysis of 87Sr variations produced by the decay of radioactive 87Rb (t1/2 = 49.61 ± 0.16 Ga). We present methodologies to acquire in situ87Rb–87Sr data using a Thermo Scientific™ Neoma™ MC-ICP-MS coupled to a laser ablation system. The ions first pass through a mass filter that blocks ions outside of the Rb–Sr mass region. The ions then travel through a hexapole collision cell filled with SF6, inducing the fluorination of Sr+ to form SrF+. Strontium isotopes are measured as SrF+ free of interferences, while rubidium isotopes are measured as Rb+. Formulas are presented to calculate the error ellipses of 87Rb/86Sr and 87Sr/86Sr ratios corrected for instrumental fractionation by standard bracketing. While LA-MC-ICP-MS/MS is not as precise as Thermal Ionization Mass Spectrometry (TIMS), it is less destructive and sample throughput is higher. It is therefore particularly well suited to analyze small and precious samples, or to examine population characteristics. We have analyzed several terrestrial and extraterrestrial materials to showcase the unique capabilities of LA-MC-ICP-MS/MS in Sr isotopic analyses: (1) an orthoclase megacryst and other minerals from the 397 Ma Shap granite, (2) feldspar grains from the 26.5 ka Oruanui supereruption in New Zealand, (3) Durango apatite, (4) highly refractory hibonite inclusions from the Murchison meteorite, and (5) the martian meteorite NWA 7034 also known as Black Beauty. Black Beauty is a polymict breccia that contains zircons as old as 4.4 Ga but whose 40Ar/39Ar age was partially reset at 1.4 Ga. All K-feldspar grains analyzed in Black Beauty give an 87Rb–87Sr age of 2.189 ± 0.059 Ga. Most likely, the 2.2 Ga 87Rb–87Sr age represents the age of lithification. This study demonstrates the great potential of in situ87Rb–87Sr dating for analyzing samples returned by planetary exploration missions, such as those currently collected by the Perseverance rover on Mars, or those that will be returned from Phobos by the MMX mission. [ABSTRACT FROM AUTHOR]

In-cell NMR of macromolecules has gained momentum over the last ten years as an approach that might bridge the branches of cell biology and structural biology. In this review, we put it in the context of earlier efforts that aimed to characterize by NMR the cellular environment of live cells and their intracellular metabolites. Although technical aspects distinguish these earlier in vivo NMR studies and the more recent in cell NMR efforts to characterize macromolecules in a cellular environment, we believe that both share major concerns ranging from sensitivity and line broadening to cell viability. Approaches to overcome the limitations in one subfield thereby can serve the other one and vice versa. The relevance in biomedical sciences might stretch from the direct following of drug metabolism in the cell to the observation of target binding, and thereby encompasses in-cell NMR both of metabolites and macromolecules. We underline the efforts of the field to move to novel biological insights by some selected examples. [ABSTRACT FROM AUTHOR]

Aharonov-Bohm (AB) interferences in the quantum Hall regime can be achieved, provided that electrons are able to transmit between two edge channels in nanostructures. Pioneering approaches include quantum point contacts in 2DEG systems, bipolar graphene p - n junctions, and magnetic field heterostructures. In this work, defect scattering is proposed as an alternative mechanism to achieve AB interferences in polycrystalline graphene. Indeed, due to such scattering, the extended defects across the sample can act as tunneling paths connecting quantum Hall edge channels. Consequently, strong AB oscillations in the conductance are predicted in polycrystalline graphene systems with two parallel grain boundaries. In addition, this general approach is demonstrated to be applicable to nano-systems containing two graphene barriers with functional impurities and perspectively, can also be extended to similar systems of 2D materials beyond graphene., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Nuclear magnetic resonance is a ubiquitous spectroscopic tool to explore molecules with atomic resolution. Nuclear magnetic relaxation is intimately connected to molecular motions. Many methods and models have been developed to measure and interpret the characteristic rates of nuclear magnetic relaxation in proteins. These approaches shed light on a rich and diverse range of motions covering timescales from picoseconds to seconds. Here, we introduce some of the basic concepts upon which these approaches are built and provide a series of illustrations. [ABSTRACT FROM AUTHOR]

We study the influence of locally doped silicon substrates on the electroreduction of diazonium salts. Our results show that the reduction of diazonium salts occurs at moderate potentials compared to the flat band potential of the semiconducting electrode. The underlying doping directs the electrografting, preferentially over doped areas of the substrate. High resolution spatially resolved X-ray photoelectron spectroscopy analysis using a new X-ray photoelectron emission microscope (XPEEM) and soft X-ray synchrotron radiation yields the thickness of the native oxide of the micron scale doped pattern on the substrate. The results as a function of both parameters—reduction potential compared to the flat band potential and thickness of the oxide layer—are discussed. These new results are then compared to data obtained on the localized electrografting of vinylic monomers. [ABSTRACT FROM AUTHOR]

N-Chloro-N′-(p-fluorophenyl)-benzamidine (NCLBA) is a N-halamine derivative which can easily release chlorine, for example when stimulated by high-energy photons. Despite the rich chemistry performed by N-halamines, the chemical properties of the N–Cl bond are poorly investigated. In this work, we determine the accurate charge density distribution of NCLBA by single crystal X-ray diffraction. A very low temperature (T = 17.5 K), coupled with the low X-ray flux of a fine-focus conventional source, allowed the specimen to survive for longer than 750 h of data acquisition without appreciable diffraction deterioration. Electronic and electrostatic properties of NCLBA are not significantly affected by the crystal field, enabling the derivation of molecular properties from the X-ray experimental data. The N–Cl bond in NCLBA is one of the longest reported to date in available structural studies. In general, the longer the N-halogen bond, the lower the amount of electron sharing in the internuclear region, with the bond approaching its homolytic dissociation limit. The synergy between accurately measured high-order data and low temperature enabled modelling of the residual thermal motion anharmonicity of the molecule's halogen atoms with refinement of Gram–Charlier thermal cumulants at the expense of large parameter correlations, as the data extension is rather short of the Kuhs empirical rule. [ABSTRACT FROM AUTHOR]

Current climate issues and the ongoing depletion of oil reserves have led to increased attention for biobased production processes. Not only has the production of bio-energy gained interest, but also the production of biochemicals. Succinate is one of those biochemicals. In the presented work, the dicarboxylic acid transport system of Escherichia coli was modified to enhance production of succinate, a highly attractive chemical building block. The engineering comprised the elimination of succinate uptake and the overexpression of succinate export. However, succinate export in Escherichia coli is normally only active under anaerobic conditions and import only under aerobic conditions. Therefore, the gene responsible for succinate import, dctA, was knocked out and the gene coding for succinate export, dcuC, was overexpressed with a constitutive artificial promoter. In the applied batch cultivations, these modifications increased succinate yield and specific production rate more than 50% in a ΔsdhAΔsdhB background (0.16 C-mole/C-mole glucose and 0.17 C-mole/C-mole biomass/h, respectively), but also revealed alternative succinate import proteins, YdjN and YbhI. Mutations in the genes coding for these proteins led to increased growth rates and specific production rates, however, they did not increase succinate yield (e.g. the deletion of ybhI resulted in a growth rate of 0.54 h−1 and a specific production rate of 0.23 C-mole/C-mole biomass/h). [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) is a ubiquitous branch of spectroscopy that can explore matter at the scale of an atom. Significant improvements in sensitivity and resolution have been driven by a steady increase of static magnetic field strengths. However, some properties of nuclei may be more favourable at low magnetic fields. For example, transverse relaxation due to chemical shift anisotropy increases sharply at higher magnetic fields leading to line-broadening and inefficient coherence transfers. Here, we present a two-field NMR spectrometer that permits the application of rf-pulses and acquisition of NMR signals in two magnetic centres. Our prototype operates at 14.1 T and 0.33 T. The main features of this system are demonstrated by novel NMR experiments, in particular a proof-of-concept correlation between zero-quantum coherences at low magnetic field and single quantum coherences at high magnetic field, so that high resolution can be achieved in both dimensions, despite a ca. 10 ppm inhomogeneity of the low-field centre. Two-field NMR spectroscopy offers the possibility to circumvent the limits of high magnetic fields, while benefiting from their exceptional sensitivity and resolution. This approach opens new avenues for NMR above 1 GHz.

We present a comparison of various computational approaches aiming at predicting the binding free energy in ligand–protein systems where the ligand is located within a highly hydrophobic cavity. The relative binding free energy between similar ligands is obtained by means of the thermodynamic integration (TI) method and compared to experimental data obtained through isothermal titration calorimetry measurements. The absolute free energy of binding prediction was obtained on a similar system (a pyrazine derivative bound to a lipocalin) by TI, potential of mean force (PMF) and also by means of the MMPBSA protocols. Although the TI protocol performs poorly either with an explicit or an implicit solvation scheme, the PMF calculation using an implicit solvation scheme leads to encouraging results, with a prediction of the binding affinity being 2 kcal mol−1 lower than the experimental value. The use of an implicit solvation scheme appears to be well suited for the study of such hydrophobic systems, due to the lack of water molecules within the binding site. [ABSTRACT FROM AUTHOR]

Thermoelectric materials can interconvert heat and electricity, and the extraordinary thermoelectric properties of lead chalcogenides (PbX, X = S, Se, Te) attract immense scientific interest. A key topic is the role of the cation in reaching a very low thermal conductivity necessary for efficient energy conversion. Here we present new structural insights about the deceptively simple rock-salt lead chalcogenides through a comparative multi-temperature synchrotron powder X-ray diffraction study. For the first time, the presence of anisotropic microstrain broadening as well as lead vacancies are quantified for all three compounds. The microstrain implies extended breakage of cubic symmetry as a sign of the incipient ferroelectric nature of PbX. The degree of microstrain is correlated to the transition pressure of a symmetry reducing phase transition, and this trend can be explained by anion mediated s–p hybridization on lead. The observed number of vacancies is greatest for PbS (4–8%), but two samples of PbS show different cation occupancy, and thus sample-dependent vacancies might be the property that unifies conflicting results reported for PbX. Gram–Charlier analysis identifies a local non-spherical distribution of Pb; however, model unbiased maximum entropy analysis indicates that any static displacement of Pb, if present, is less than 0.2 Å at 100 K. [ABSTRACT FROM AUTHOR]

Materials and their interfaces are the core for the development of a large variety of fields, including catalysis, energy storage and conversion. In this case, tip-enhanced Raman spectroscopy (TERS), which combines scanning probe microscopy with plasmon-enhanced Raman spectroscopy, is a powerful technique that can simultaneously obtain the morphological information and chemical fingerprint of target samples at nanometer spatial resolution. It is an ideal tool for the nanoscale chemical characterization of materials and interfaces, correlating their structures with chemical performances. In this review, we begin with a brief introduction to the nanoscale characterization of materials and interfaces, followed by a detailed discussion on the recent theoretical understanding and technical improvements of TERS, including the origin of enhancement, TERS instruments, TERS tips and the application of algorithms in TERS. Subsequently, we list the key experimental issues that need to be addressed to conduct successful TERS measurements. Next, we focus on the recent progress of TERS in the study of various materials, especially the novel low-dimensional materials, and the progresses of TERS in studying different interfaces, including both solid–gas and solid–liquid interfaces. Finally, we provide an outlook on the future developments of TERS in the study of materials and interfaces. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effect of mixed surface terminations (F, O, OH) on the properties of M2C MXenes (M = Sc, Ti, V). We explore how different compositions and patterns of terminal groups affect the stability and electronic properties of these 2D materials. The bond dissociation energies and cohesion energies show a clear preference for F-terminations in Sc2C, while Ti- and V-based MXenes prefer O-terminations. Our study is the first to demonstrate that terminal groups on opposite sides of the MXene have little to no influence on each other's electronic structure, allowing for independent chemical environments on each side. In a first of its kind investigation semiconducting forms of studied MXenes (Sc2CF2, Sc2C(OH)2 and Ti2CO2) showed very high sensitivity to conduction-inducing terminations (O, O, and F, respectively) with even minuscule amounts (≈1%) causing the materials to become conductive. This high sensitivity of the band gap to surface terminations may offer an explanation for the challenges in synthesizing semiconducting forms of MXenes. [ABSTRACT FROM AUTHOR]

Photodetectors based on two-dimensional materials have attracted significant attention due to their unique structure and outstanding optoelectronic properties. However, large dark current and extended response time have become bottlenecks for further practical application. In this work, a WS2/AsP van der Waals heterojunction (vdWHs) with a type-II band structure has been fabricated. The built-in electric field at the interface can effectively suppress dark currents and separate photo-generated charge carriers, enhancing photoelectric characteristics. At room temperature, the device exhibits a switching ratio of 107 and a rectification ratio of 105. Under a 532 nm laser illumination, the photodetector presents outstanding characteristics: the detectivity exceeds 1.72 × 1013 jones, the responsivity achieves approximately 14.6 A W−1, the external quantum efficiency reaches up to 4120%, and the response time is in the millisecond range. Our results indicate that WS2/AsP heterojunctions hold promising prospects for future optoelectronic applications. [ABSTRACT FROM AUTHOR]

The sodium tellurosilicates Na4SiTe4, Na10Si2Te9, Na6Si2Te6 and Na8Si4Te10 were synthesized by ball milling and subsequent high temperature solid state reactions and analyzed by electrochemical impedance spectroscopy. All compounds show moderate to remarkable sodium ion conductivities. The crystal structures of the novel materials Na4SiTe4 and Na10Si2Te9 were determined by X-ray diffraction. Both compounds represent new structure types with isolated SiTe4 tetrahedra. The crystal structure of Na10Si2Te9 exhibits a single telluride anion besides two SiTe4 tetrahedra. Na4SiTe4 crystallizes in the cubic space group Pa3¯ (no. 205) with lattice parameters a = 13.0312(1) Å and V = 2212.84(2) Å3. Na10Si2Te9 crystallizes in the orthorhombic space group Pna21 (no. 33) with lattice parameters a = 12.8235(7) Å, b = 14.8398(8) Å, c = 12.9530(7) Å and V = 2464.9(2) Å3. The presence of two different anionic units makes this compound stand out from other alkali chalcogenotetrelates. The electronic structure of all compounds was investigated by density functional theory, revealing their semiconducting behaviour. [ABSTRACT FROM AUTHOR]

Chlorine isotopic ratio measurements are useful for stable isotope tracing, isotopic abundance measurements in nuclear chemistry, and accurate determination of concentrations using isotope dilution methods. Accurate and precise determination of Cl isotopic ratios using inductively coupled plasma mass spectrometry (ICP-MS) methods is challenging due to major polyatomic interferences of 16O18O¹H+ and 36Ar¹H+ on 35Cl+ and 37Cl+, respectively. Previous work has demonstrated that using tandem mass spectrometry (ICP-MS/MS) with either H2 or O2 gas in the collision/reaction cell can significantly improve the precision, but not necessarily the accuracy, of chlorine isotopic measurements over single-quadrupole techniques. In this work, we further investigate ICP-MS/MS, using O2 as a reaction gas, as a technique for accurate determination of Cl isotopic ratios. Using the methodology developed herein we measure both natural and enriched chlorine isotopic ratios in diverse samples matrices, targeting 37Cl isotope enrichment efforts, without the need for complex front-end chemistry (i.e., ion exchange chromatography), while maintaining a typical accuracy and precision better than ~1%. The reduced need for time-consuming sample processing afforded by this method results in higher sample throughput (>80 measurements/day) relative to other analytical techniques (e.g., thermal ionization mass spectrometry, accelerator mass spectrometry, etc.). This work demonstrates that ICPMS/MS with O2 as a reaction gas can be a useful tool for making rapid and accurate chlorine isotopic ratio measurements. [ABSTRACT FROM AUTHOR]

Achieving facile and simple temperature- and pressure-induced transformation of sp2-to-sp3 remains an important and fascinating challenge within the realm of carbon science and technology. Here, we introduce a new technique that utilizes repeated exposure of low-pressure (2.0 MPa) millisecond acoustic shock waves on a sample to facilitate the successful transformation of sp2-to-sp3 carbon bonds. This transformation is verified through visible Raman spectroscopic, X-ray photoelectron spectroscopic (XPS), and high-resolution transmission electron microscopic (HRTEM) observations. Typically, in general nanosecond dynamic compression experiments, sp3 carbon bond formation occurs only at pressures of ∼45 GPa or more, and under static compression, this transition takes place at ∼30 GPa. However, with our innovative approach, similar results can be achieved with acoustic shock waves operating at significantly lower pressures of 2.0 MPa. Based on the observed analytical results, the sp2-to-sp3 type phase transition occurred at the 500-shocked condition and this transition leads to the conversion of layered crystalline graphite to non-layered amorphous graphite, which may be the pre-state of sp3 bonded diamond formation. The complete disappearance of the 2D band in the Raman spectrum and the conversion of asymmetric to symmetric shape of the C 1s band in the XPS spectrum are the major proof for the proposed sp2-to-sp3 phase transition. Further optimization is currently underway to find the critical point in achieving the probable phase transition of graphite to diamond. The proposed technique put forward a platform for a new impending way to make the sp3 carbons from sp2 carbons in indoor laboratories, which may also offer a new science division to understand the formation of diamonds or diamond-like structures under lower transient pressure conditions. Even though the proposed technique is cost-effective and involves a handy tool, to move it from lab to industrial applications, we still have a lot of ground to cover in fundamental aspects. [ABSTRACT FROM AUTHOR]

Grasping the intricate π–π interactions between redox-active organic materials and conductive carbons is key to optimizing the performance of organic electrodes in energy storage devices. However, their precise role in redox chemistry remains elusive. In this work, the geometric congruence between the triptycene-phenazine (Trip-Phz) molecule, with its paddle-wheel structure, and the curved single-walled carbon nanotubes (SWCNTs), enables the self-assembly of Trip-Phz/SWCNT composites for aqueous supercapacitors. The Trip-Phz/SWCNT composites demonstrate well-defined redox peaks on cyclic voltammograms, coupled with a specific capacitance of 410 F g−1. Our study goes one step further by capturing the electrochemically induced radicals through electron spin resonance (ESR) spectroscopy. The theoretically predicted robust π–π interactions between the inner-layer Trip-PhzH63˙+ radicals and SWCNTs facilitate the electron transfer effect, leading to an ESR silent state. Conversely, the ESR spectra of the outer-layer radicals feature a Dysonian line, attributive of the high conductivity of the Trip-Phz/SWCNT composites (∼102 S cm−1). The insights gained from this research inspire the design of stable organic/carbon electrodes for advanced energy storage devices. [ABSTRACT FROM AUTHOR]

The tertiary and quaternary structures of many proteins are stabilized by strong covalent forces, of which disulfide bonds are the most well known. A new type of intramolecular and intermolecular covalent bond has been recently reported, consisting of the Lys and Cys side-chains linked by an oxygen atom (NOS). These post-translational modifications are widely distributed amongst proteins, and are formed under oxidative conditions. Similar linkages are observed during antibiotic biosynthesis, where hydroxylamine intermediates are tethered to the sulfur of enzyme active site Cys residues. These linkages open the way to understanding protein structure and function, give new insights into enzyme catalysis and natural product biosynthesis, and offer new strategies for drug design. [ABSTRACT FROM AUTHOR]

The advent of femtosecond to attosecond experimental tools has made now possible to study such ultrafast carrier dynamics, e.g., the spatial and temporal charge density evolution, after an initial oxidation or reduction in molecules, candidates for atomic wires like polyynes and dicyanopolyynes. Here, we study the electronic structure and hole transfer in symmetric molecules containing carbon, nitrogen and hydrogen, the first members in the series of polyynic carbynes and dicyanopolyynes, using methods based on density functional theory (DFT): constrained DFT (CDFT), time-dependent DFT (TDDFT) and real-time TDDFT (RT-TDDFT), with Löwdin population analysis, comparing many levels of theory and obtaining convergence of the results. For the same purposes, we develop a tight binding (TB) variant using all valence orbitals of all atoms. This TB variant is applied here in linear molecules, but it is also adequate for electronic structure, charge transfer and charge transport of non-linear molecules and clusters of molecules. We calculate the electronic structure, the time-dependent dipole moment and the probabilities of finding the hole at each site, their mean over time values, the mean transfer rates from the oxidation site to other sites and the frequency content (using charge as well as dipole moment oscillations). We take into account zero-point motion. The initial conditions for RT-TDDFT are obtained by CDFT. For TB, we explore different initial conditions: we place the hole at a particular orbital or distribute it among a number of orbitals; it is also possible to include phase differences between orbitals. Finally, we compare with available experimental data. [ABSTRACT FROM AUTHOR]

With the versatile utility of bio-conjugated peptides and proteins in the fields of agriculture, food, cosmetics and pharmaceutical industry, the design of smart protocols to conjugate and modulate biomolecules becomes highly desirable. During this process, the most important consideration for biochemists is the retention of configurational integrity of the biomolecules. Moreover, this type of bioconjugation of peptide and protein becomes frivolous if the reaction is not performed with precise amino acid residues. Hence, chemo-selective, as well as site-selective reactions, that are biocompatible and possess an appropriate level of reactivity are necessary. Based on click chemistry, there are so many tyrosine (Y) conjugation strategies, such as sulfur-fluoride exchange (SuFEx), sulfur-triazole exchange (SuTEx), coupling with π-allyl palladium complexes, diazonium salts, diazodicarboxyamide-based reagents etc. Among these techniques, diazodicarboxyamide-based Y-conjugation, which is commonly known as the "tyrosine-click (Y-click) reaction", has met the expectations of synthetic and biochemists for the tyrosine-specific functionalization of biomolecules. Over the past one and a half decades, significant progress has been made in the classical organic synthesis approach, as well as its biochemical, photochemical, and electrochemical variants. Despite such progress and increasing importance, the Y-click reaction has not been reviewed to document variations in its methodology, applications, and broad utility. The present article aims to provide a summary of the approaches for the modulation of biomolecules at the hotspot of tyrosine residue by employing the Y-click reaction. The article also highlights its application for the mapping of proteins, imaging of living cells, and in the fields of analytical and medicinal chemistry. [ABSTRACT FROM AUTHOR]

Natural processes, from cosmochemistry to human homeostasis, can be traced by means of the mass-dependent fractionation of K isotopes because the 39K/41K ratio is characterized by a wide range of variations (ca. 3‰). The measurement of the 39K/41K ratio is traditionally achieved by multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), but is significantly impeded by large isobaric argide interferences on K isotopes. A new generation of MC-ICPMS equipped with a collision/reaction cell allows the quantitative elimination of argide interferences using H2 as a reaction gas. We report on a set of high-precision K isotopic data obtained with the recently released ThermoScientific Neoma MC-ICPMS/MS equipped with a prefiltering system consisting of a double-Wien filter and a collision/reaction cell. In the low-resolution mode, the mass resolving power is ca. 2200, resulting in a K sensitivity of ca. 1000 V ppm-1 for 39K in dry mode with an Apex Omega desolvator. This large mass revolving power allows the observation of yet undetected interferences on the high-mass shoulders of 39K and 41K. The interference is ca. 25 mV on 39K and 1 mV on 41K in the low-resolution mode, similar in K and blank HNO3 (0.05 M) solutions, increases when N2 is added in the desolvator and decreases when He is added as a collision gas. The presence of these interferences, which contribute modestly < 0.02% of the K signal, is probably the result of the formation of complex organic compounds in the collision/reaction cell. However, blank subtraction is a critical step to achieve steady and accurate analysis of the 39K/41K ratio. The overall stability of the analysis of the 39K/41K ratio is greatly improved by using a continuous-flow microFAST Isotope autosampler. A survey on the potential effects of sample-standard mismatches reveals significant offsets for matrix elements (Ca, Mg and Na), no offset for acid molarity. Regarding the effect of sample-standard concentration mismatch, we show that the amplitude of the offset is session-dependent, such that no general correction could be applied. We use the autosampler adjustable injection flow rate to correct for a concentration mismatch up to ± 30% to recover expected K isotope composition within the ± 0.05‰ uncertainty. In these conditions, short-term external precision and long-term reproducibility are 0.07‰ (2SD, n = 500) and 0.08‰ (2SD, n = 66), respectively. For validation of the overall method, we finally purified K using a single step chemical separation by ion exchange chromatography, and measured the K isotope composition of geological and biological reference materials, for which we found values similar to the literature. Our study shows that the Neoma MC-ICPMS/MS with continuous flow injection is a robust instrumentation that will contribute to expediting high-precision K isotopic measurements for various applications. [ABSTRACT FROM AUTHOR]

Tissue engineering has emerged as a remarkable field aiming to restore or replace damaged tissues through the use of biomimetic constructs. Among the diverse materials investigated for this purpose, nanocellulose-based hydrogels have garnered attention due to their intriguing biocompatibility, tunable mechanical properties, and sustainability. Over the past few years, numerous research works have been published focusing on the successful use of nanocellulose-based hydrogels as artificial extracellular matrices for regenerating various types of tissues. The review emphasizes the importance of tissue engineering, highlighting hydrogels as biomimetic scaffolds, and specifically focuses on the role of nanocellulose in composites that mimic the structures, properties, and functions of the native extracellular matrix for regenerating damaged tissues. It also summarizes the types of nanocellulose, as well as their structural, mechanical, and biological properties, and their contributions to enhancing the properties and characteristics of functional hydrogels for tissue engineering of skin, bone, cartilage, heart, nerves and blood vessels. Additionally, recent advancements in the application of nanocellulosebased hydrogels for tissue engineering have been evaluated and documented. The review also addresses the challenges encountered in their fabrication while exploring the potential future prospects of these hydrogel matrices for biomedical applications. [ABSTRACT FROM AUTHOR]

We investigate the structural, electronic, and optical properties of eight possible Zr2CO2/GaS van der Waals (vdW) heterostructures using first-principles calculations based on a hybrid functional. These structures display favorable stability, indicated by matching crystal structures and negative formation energies. In all considered configurations, these heterostructures act as indirect band gap semiconductors with a type-II band alignment, allowing efficient electron-hole separation. Optical studies reveal their suitability for optoelectronic applications. Zr2CO2/GaS under 4% biaxial compressive strain meets the criteria for photocatalytic water splitting, suggesting their potential for electronic and optoelectronic devices in the visible spectrum. Our findings present prospects for advanced photocatalytic materials and optical devices. [ABSTRACT FROM AUTHOR]

In recent years, the development of sustainable and cost-effective electrocatalysts for nitrogen (N2) fixation has garnered significant attention, leading to the introduction of next-generation materials with electrocatalytic properties. Among the most interesting types of these materials, MXenes and their composite forms with their unique properties like high electrochemical activity, large surface area, tunable properties, excellent electrical conductivity, chemical stability, and abundant transition metals have been widely explored. These properties make MXenes promising candidates for various electrochemical reactions, including water splitting, oxygen reduction, hydrogen evolution, N2 activation and reduction, among others. The interface of these materials could be engineered with other entities which can serve as a promising tool for sustainable production of ammonia (NH3) to address the global nitrogen-related challenges. Moreover, optimizing the interfaces between them and reactants is another way to achieve high catalytic activity, selectivity, and stability. Accordingly, this review aims to offer a comprehensive overview of the current state of research in the field of electrocatalytic N2 fixation deploying MXenes and their composites. The highlights comprise progress made in understanding the catalytic properties and unique performances of MXenes for N2 fixation, as well as challenges that persist in this context and the possible solutions that could be implemented to circumvent these challenges in the future. [ABSTRACT FROM AUTHOR]

Recent advancements in materials science have shed light on the potential of exploring hierarchical assemblies of molecules on surfaces, driven by both fundamental and applicative challenges. This field encompasses diverse areas including molecular storage, drug delivery, catalysis, and nanoscale chemical reactions. In this context, the utilization of nanotube templates (NTs) has emerged as promising platforms for achieving advanced one-dimensional (1D) molecular assemblies. NTs offer cylindrical, crystalline structures with high aspect ratios, capable of hosting molecules both externally and internally (Mol@NT). Furthermore, NTs possess a wide array of available diameters, providing tunability for tailored assembly. This review underscores recent breakthroughs in the field of Mol@NT. The first part focuses on the diverse panorama of structural properties in Mol@NT synthesized in the last decade. The advances in understanding encapsulation, adsorption, and ordering mechanisms are detailed. In a second part, the review highlights the physical interactions and photophysics properties of Mol@NT obtained by the confinement of molecules and nanotubes in the van der Waals distance regime. The last part of the review describes potential applicative fields of these 1D heterostructures, providing specific examples in photovoltaics, luminescent materials, and bio-imaging. A conclusion gathers current challenges and perspectives of the field to foster discussion in related communities. [ABSTRACT FROM AUTHOR]

The development and ongoing discovery of 2D materials and their emergent optical and electronic properties have led to intense interest in the stacking of different 2D materials into layered heterostructures. While the initial efforts focused on mechanical transfer of 2D materials and vapor-phase epitaxial growth, there is an increasing body of research on colloidal methods for the fabrication of layered heterostructures. This review gives insight into the history and development of layered heterostructures composed of stacked 2D materials, starting from the origins of 2D materials research and leading up to the current state-of-the-art methods for fabricating 2D material heterostructures. Particular attention is given to colloidal approaches, with emphasis on the importance of surface chemistry in controlling both the assembly of dispersed 2D materials and direct colloidal synthesis at 2D material interfaces to achieve well-defined heterostructures. Approaches from diverse fields of chemistry such as the synthesis of 2D Janus nanosheets, modification of interlayer spaces of 2D materials, and colloidal atomic layer deposition give insight into potential future colloidal strategies. In summary, this review provides an overview of the basics of 2D material heterostructures and their fabrication, while also suggesting future colloidal avenues for the development of hybrid nanomaterials which would greatly benefit applications in (photo)catalysis, energy storage, sensing, optoelectronics, and more. [ABSTRACT FROM AUTHOR]

Manganese-based MXenes are promising two-dimensional materials due to the broad palette of their magnetic phases and the possibility of experimental preparation because the corresponding MAX phase was already prepared. Here, we systematically investigated geometrical conformers and spin solutions of oxygen-terminated Mn2C MXene and performed subsequent many-body calculations to obtain reliable electronic and optical properties. Allowing energy-lowering using the correct spin ordering via supercell magnetic motifs is essential for the Mn2CO2 system. The stable ground-state Mn2CO2 conformation is antiferromagnetic (AFM) with zigzag lines of up and down spins on Mn atoms. The AFM nature is consistent with the parent MAX phase and even the clean depleted Mn2C sheet. Other magnetic states and geometrical conformations are energetically very close, providing state-switching possibilities in the material. Subsequent many-body GW and Bethe–Salpeter equation (BSE) calculations provide indirect semiconductor characteristics of AFM Mn2CO2 with a fundamental gap of 2.1 eV (and a direct gap of 2.4 eV), the first bright optical transition at 1.3 eV and extremely strongly bound (1.1 eV) first bright exciton. Mn2CO2 absorbs efficiently the whole visible light range and near ultraviolet range (between 10 and 20%). [ABSTRACT FROM AUTHOR]

Chondrogenesis is a complex cellular process that involves the transformation of mesenchymal stem cells (MSCs) into chondrocytes, the specialised cells that form cartilage. In recent years, three-dimensional (3D) culture systems have emerged as a promising approach to studying cell behaviour and development in a more physiologically relevant environment compared to traditional two-dimensional (2D) cell culture. The use of these systems provided insights into the molecular mechanisms that regulate chondrogenesis and has the potential to revolutionise the development of new therapies for cartilage repair and regeneration. This study demonstrates the successful application of Raman microspectroscopy (RMS) as a label-free, non-destructive, and sensitive method to monitor the chondrogenic differentiation of bone marrow-derived rat mesenchymal stem cells (rMSCs) in a collagen type I hydrogel, and explores the potential benefits of 3D hydrogels compared to conventional 2D cell culture environments. rMSCs were cultured on 3D substrates for 3 weeks and their differentiation was monitored by measuring the spectral signatures of their subcellular compartments. Additionally, the evolution of high-density micromass cultures was investigated to provide a comprehensive understanding of the process and complex interactions between cells and their surrounding extracellular matrix. For comparison, rMSCs were induced into chondrogenesis in identical medium conditions for 21 days in monolayer culture. Raman spectra showed that rMSCs cultured in a collagen type I hydrogel are able to undergo a distinct chondrogenic differentiation pathway at a significantly higher rate than the 2D culture cells. 3D cultures expressed stronger and more homogeneous chondrogenesis-associated peaks such as collagens, glycosaminoglycans (GAGs), and aggrecan while manifesting changes in proteins and lipidic content. These results suggest that 3D type I collagen hydrogel substrates are promising for in vitro chondrogenesis studies, and that RMS is a valuable tool for monitoring chondrogenesis in 3D environments. [ABSTRACT FROM AUTHOR]

Potassium isotopes hold great promise for tracing geological processes, but their analyses are fraught with complexities. Various methods using different generations of MC-ICPMS instruments have been developed, each with distinct advantages and disadvantages. In this study, we report on K isotopic measurements performed using the Thermo Fisher Scientific Neoma collision cell MC-ICPMS/MS to explore the potential of the instrument. Tests were conducted under wet plasma conditions and the precision achieved was ~0.03 to 0.1& (95% c.i.) for 5-25 measurements in a single analytical session, comparable to other established techniques. The measurements were accurate within the tested concentration range of 50-500 ppb K. A K concentration mismatch between samples and standards of up to 5% was acceptable, while acid molarity mismatch had a pronounced effect on the measured K isotopic compositions. Matrix elements did not significantly impact K isotopic measurements when their concentration was below 2% of K. Several geostandards were measured and the obtained values agree with those from other measurement techniques. Overall, our tests suggest that measuring K isotopes with Neoma collision cell MC-ICPMS/MS is possible, but the high sensitivity of the instrument to tuning settings requires considerable efforts for conducting such measurements. [ABSTRACT FROM AUTHOR]

We present a comparison of various computational approaches aiming at predicting the binding free energy in ligand-protein systems where the ligand is located within a highly hydrophobic cavity. The relative binding free energy between similar ligands is obtained by means of the thermodynamic integration (TI) method and compared to experimental data obtained through isothermal titration calorimetry measurements. The absolute free energy of binding prediction was obtained on a similar system (a pyrazine derivative bound to a lipocalin) by TI, potential of mean force (PMF) and also by means of the MMPBSA protocols. Although the TI protocol performs poorly either with an explicit or an implicit solvation scheme, the PMF calculation using an implicit solvation scheme leads to encouraging results, with a prediction of the binding affinity being 2 kcal mol(-1) lower than the experimental value. The use of an implicit solvation scheme appears to be well suited for the study of such hydrophobic systems, due to the lack of water molecules within the binding site.

This study delves into the magneto-electronic and magneto-optical properties of stacking-modulated bilayer graphene. By manipulating domain walls (DWs) across AB–BA domains periodically, we unveil oscillatory Landau subbands and the associated optical excitations. The DWs act as periodic potentials, yielding fascinating 1D spectral features. Our exploration reveals 1D phenomena localized to Bernal stacking, DW regions, and stacking boundaries, highlighting the intriguing formation of Landau state quantization influenced by the commensuration between the magnetic length and the system. The stable quantized localization within different regions leads to the emergence of unconventional quantized subbands. This study provides valuable insights into the essential properties of stacking-modulated bilayer graphene. [ABSTRACT FROM AUTHOR]