Search

Heat feedback to the unburned reaction interface is an important controlling factor of the velocity of the reaction front and power delivery. In this paper, we investigate the effect of agglomerate surface tension and its relationship to surface residence time and heat feedback on the combustion characteristics by Si addition to an Al/KClO4composite. Macroscopic imaging demonstrates a significant increase in burn rate with the addition of Si despite the fact that Si/KClO4has a slightly lower energy density than Al/KClO4. Microscopic imaging coupled with three-color pyrometry reveals that molten liquid forms and evolves into spherical droplets on the burning surface, which are subsequently ejected from the surface. We find that the addition of Si results in a small increase in droplet size and a negligible impact on droplet temperature. However, the droplet formation rate on the surface is slower, leading to a significantly longer surface residence time. This leads to enhanced conductive heat feedback to the unburnt materials, thereby increasing the burn rate and energy release rate. We attribute the decreased droplet growth rate to the lowered surface tension of the liquid mixture with Si addition. This study highlights the crucial role of agglomerate physical property (e.g., surface tension) in influencing the combustion behavior of energetic composites.

Dopants and alloying elements are commonly introduced in amorphous carbon (a-C) materials to tailor their mechanical and tribological properties. While most published studies have focused on doping and alloying a-C coatings with metals or metalloids, doping a-C films with rare-earth elements has only recently been explored. Notably, our understanding of the shear-induced structural changes occurring in rare-earth-element-containing a-C films is still elusive, even in the absence of any liquid lubricants. Here, the friction response of Eu- and Gd-containing a-C films with low hydrogen content deposited by HiPIMS on silicon was evaluated in open air and at room temperature. The load-dependent friction measurements indicated that the introduction of Gd ((2.3 ± 0.1) at.%) and Eu ((2.4 ± 0.1) at.%) into the a-C matrix results in a significant reduction of the shear strength of the sliding interfaces ((41 ± 2) MPa for a-C, (16 ± 1) MPa for a-C:Gd2.3 at.%, and (11 ± 2) MPa for a-C:Eu2.4 at.%). NEXAFS spectromicroscopy experiments provided evidence that no stress-assisted sp3-to-sp2rehybridization of carbon atoms was induced by the sliding process in the near-surface region of undoped a-C, while the amount of sp2-bonded carbon progressively increased in a-C:Gd2.3 at.%and a-C:Eu2.4 at.%upon increasing the applied normal load in tribological tests. The formation of an sp2-bonded carbon-rich surface layer in a-C:Gd2.3 at.%and a-C:Eu2.4 at.%films was not only proposed to be the origin for the reduced duration of the running-in period in tribological test, but was also postulated to induce shear localization within the sp2-carbon-rich layer and transfer film formation on the countersurface, thus decreasing the interfacial shear strength. These findings open the path for the use of Gd- and Eu-containing a-C even under critical conditions for nearly hydrogen-free a-C films (i.e., humid air).

The categorical approach in psychiatry has received many criticisms. Modern research tends to develop a transdiagnostic approach. However, transdiagnostic works lack an overall understanding and focus mainly on anxiety and depression. The aim of the present study was to develop an easy to use tool to evaluate multiple dimensions opening the way for further research in the transdiagnostic approach. This will allow researchers to quickly assess the efficacy of psychotherapeutic interventions on multiple psychopathological dimensions.

Initially observed on synthetic nanoparticles, the existence of biomolecular corona and its role in determining nanoparticle identity and function are now beginning to be acknowledged in biogenic nanoparticles, particularly in extracellular vesicles – membrane-enclosed nanoparticle shuttling proteins, nucleic acids, and metabolites which are released by cells for physiological and pathological communication – we developed a methodology based on fluorescence correlation spectroscopy to track biomolecular corona formation on extracellular vesicles derived from human red blood cells and amniotic membrane mesenchymal stromal cells when these vesicles are dispersed in human plasma. The methodology allows for tracking corona dynamics in situunder physiological conditions. Results evidence that the two extracellular vesicle populations feature distinct corona dynamics. These findings indicate that the dynamics of the biomolecular corona may ultimately be linked to the cellular origin of the extracellular vesicles, revealing an additional level of heterogeneity, and possibly of bionanoscale identity, that characterizes circulating extracellular vesicles.

Hybrid structures formed between organic molecules and inorganic quantum dots can accomplish unique photophysical transformations by taking advantage of their disparate properties. The electronic coupling between these materials is typically weak, leading photoexcited charge carriers to spatially localize to the dot or to a molecule at its surface. However, we show that by converting a chemical linker that covalently binds anthracene molecules to silicon quantum dots from a carbon–carbon single bond to a double bond, we access a strong coupling regime where excited carriers spatially delocalize across both anthracene and silicon. By pushing the system to delocalize, we design a photon upconversion system with a higher efficiency (17.2%) and lower threshold intensity (0.5 W cm–2) than that of a corresponding weakly coupled system. Our results show that strong coupling between molecules and nanostructures achieved through targeted linking chemistry provides a complementary route for tailoring properties in materials for light-driven applications.

Eutectic mixtures are usually studied by differential scanning calorimetry (DSC), able to identify the transition temperatures, possible hysteresis, and investigate the energetic features of transformations. However, DSC is not able to give compositional, structural, or morphological information. A new approach is proposed exploiting powder X-ray diffraction (XRPD) and imaging to overcome the issues posed to diffraction by the presence of an amorphous liquid phase. Principal component analysis (PCA) is applied blindly to in situ XRPD data from both solid and liquid phases in an approach called differential scanning diffraction (DSD), with PCA scores being the reaction coordinate of melting or crystallization steps. PCA was used in a similar way to analyze the imaging data in what was named differential scanning imaging (DSI). Exploiting this approach, the structural and morphological changes during phase transitions can be characterized by XRPD and imaging respectively, complementarily to the energetic effects probed by DSC. Melting and crystallization points can be identified together with the hysteresis between downward and upward temperature ramps, by the structural and morphological viewpoints. A three-component mixture (NaBr, KCl, and water), with wide industrial applications, was studied to describe the behavior around the eutectic composition and examine how small mixture changes can affect the transition temperature and the freezing/melting behaviors. The phase composition at the solid state was elucidated and a new phase of NaBr was identified and its lattice parameters were obtained by XRPD. DSD and DSI resulted complementary to traditional DSC data with many potential applications in solid state chemistry and materials science.

Biological macromolecules, especially therapeutic proteins, are delicate and highly sensitive to denaturation from stresses encountered during the manufacture of dosage forms. Thin-film freeze-drying (TFFD) and spray freeze-drying (SFD) are two processes used to convert liquid forms of protein into dry powders. In the production of inhalable dry powders that contain proteins, these potential stressors fall into three categories based on their occurrence during the primary steps of the process: (1) droplet formation (e.g., the mechanism of droplet formation, including spray atomization), (2) freezing, and (3) frozen water removal (e.g., sublimation). This study compares the droplet formation mechanism used in TFFD and SFD by investigating the effects of spraying on the stability of proteins, using lactoferrin as a model. This study considers various perspectives on the denaturation (e.g., conformation) of lactoferrin after subjecting the protein solution to the atomization process using a pneumatic two-fluid nozzle (employed in SFD) or a low-shear drop application through the nozzle. The surface activity of lactoferrin was examined to explore the interfacial adsorption tendency, diffusion, and denaturation process. Subsequently, this study also investigates the secondary and tertiary structure of lactoferrin and the quantification of monomers, oligomers, and, ultimately, aggregates. The spraying process affected the tertiary structure more negatively than the tightly woven secondary structure, resulting in the peak position corresponding to the tryptophan (Trp) residues red-shifting by 1.5 nm. This conformational change can either (a) be reversed at low concentrations via relaxation or (b) proceed to form irreversible aggregates at higher concentrations. Interestingly, when the sample was allowed to progress into micrometer-sized aggregates, such a dramatic change was not detected using methods such as size-exclusion chromatography, polyacrylamide gel electrophoresis, and dynamic light scattering at 173°. A more complete understanding of the heterogeneous protein sample was achieved only through a combination of 173 and 13° backward and forward scattering, a combination of derived count rate measurements, and microflow imaging (MFI). After studying the impact of droplet formation mechanisms on aggregation tendency of lactoferrin, we further investigated two additional model proteins with different surface activity: bovine IgG (serving as a non surface-active negative reference), and β-galactosidase (another surface-active protein). The results corroborated the lactoferrin findings that spray-atomization-related stress-induced protein aggregation was much more pronounced for proteins that are surface active (lactoferrin and β-galactosidase), but it was minimal for non-surface-active protein (bovine IgG). Finally, compared to the low-shear dripping used in the TFFD process, lactoferrin underwent a relatively fast conformational change upon exposure to the high air–water interface of the two-fluid atomization nozzle used in the SFD process as compared to the low shear dripping used in the TFFD process. The interfacial-induced denaturation that occurred during spraying was governed primarily by the size of the atomized droplets, regardless of the duration of exposure to air. The percentage of denatured protein population and associated activity loss, in the case of β-galactosidase, was determined to range from 2 to 10% depending on the air-flow rate of the spraying process.

Molybdenum trioxide (MoO3), an important transition metal oxide (TMO), has been extensively investigated over the past few decades due to its potential in existing and emerging technologies, including catalysis, energy and data storage, electrochromic devices, and sensors. Recently, the growing interest in two-dimensional (2D) materials, often rich in interesting properties and functionalities compared to their bulk counterparts, has led to the investigation of 2D MoO3. However, the realization of large-area true 2D (single to few atom layers thick) MoO3is yet to be achieved. Here, we demonstrate a facile route to obtain wafer-scale monolayer amorphous MoO3using 2D MoS2as a starting material, followed by UV–ozone oxidation at a substrate temperature as low as 120 °C. This simple yet effective process yields smooth, continuous, uniform, and stable monolayer oxide with wafer-scale homogeneity, as confirmed by several characterization techniques, including atomic force microscopy, numerous spectroscopy methods, and scanning transmission electron microscopy. Furthermore, using the subnanometer MoO3as the active layer sandwiched between two metal electrodes, we demonstrate the thinnest oxide-based nonvolatile resistive switching memory with a low voltage operation and a high ON/OFF ratio. These results (potentially extendable to other TMOs) will enable further exploration of subnanometer stoichiometric MoO3, extending the frontiers of ultrathin flexible oxide materials and devices.

The incorporation of silicon and oxygen into hydrogenated amorphous carbon (a-C:H) is an effective approach to decrease the dependence of the tribological properties of a-C:H on the environment. Here, we evaluate the effect of hydrogen and oxygen partial pressures in vacuum on the tribological response of steel pins sliding against films consisting of silicon- and oxygen-containing a-C:H (a-C:H:Si:O). Experiments are conducted in the low-friction/low-wear regime, where sufficient gas pressure prevents steel from adhering to the a-C:H:Si:O, with the velocity accommodation mode being interfacial sliding between the tribotrack formed in the a-C:H:Si:O film and the carbonaceous tribofilm that is formed on the countersurface. The experiments indicated a decrease (increase) in friction and wear with the hydrogen (oxygen) pressure (hydrogen pressures between 50 and 2000 mbar; oxygen pressures between 10 and 1000 mbar). Characterization by X-ray photoelectron and absorption spectroscopies indicated the occurrence of tribologically induced rehybridization of carbon–carbon bonds from sp3to sp2. This mechanically induced structural transformation coincided with the dissociative surface reaction between hydrogen (oxygen) gas molecules and sp2carbon–carbon bonds that are highly strained, which results in the formation of carbon–hydrogen groups (carbonyl or ether groups together with silicon atoms having higher oxidation states). On the basis of variations of the fraction of these surface functional groups with gas pressure, a phenomenological model is proposed for the gas pressure dependence of friction for steel when sliding on a-C:H:Si:O films: while the decrease in friction with hydrogen pressure is induced by an increase in the percentage of carbon–hydrogen groups, the increase in friction with oxygen pressure is caused by a progressive increase in the relative fraction of silicon atoms having higher oxidation states and an increase in surface oxygen concentration.

Biocidal nanothermite composites show great potential in combating biological warfare threats because of their high-energy-release rates and rapid biocidal agent release. Despite their high reactivity and combustion performance, these composites suffer from low-energy density because of the voids formed due to inefficient packing of fuel and oxidizer particles. In this study, we explore the potential of plasma-synthesized ultrafine Si nanoparticles (nSi, ∼5 nm) as an energetic filler fuel to increase the energy density of Al/Ca(IO3)2energetic-biocidal composites by filling in the voids in the microstructure. Microscopic and elemental analyses show the partial filling of mesoparticle voids by nSi, resulting in an estimated energy density enhancement of ∼21%. In addition, constant-volume combustion cell results show that nSi addition leads to a ∼2–3-fold increase in reactivity and combustion performance, as compared to Al/Ca(IO3)2mesoparticles. Oxidation timescale analyses suggest that nSi addition can promote initiation due to faster oxygen transport through the oxide shell of Si nanoparticles. At nSi loadings higher than ∼8%, however, slower burning characteristics of nSi and sintering effects lead to an overall degradation of combustion behavior of the composites.

Inorganic semiconductor nanocrystals interfaced with spin-triplet exciton-accepting organic molecules have emerged as promising materials for converting incoherent long-wavelength light into the visible range. However, these materials to date have made exclusive use of nanocrystals containing toxic elements, precluding their use in biological or environmentally sensitive applications. Here, we address this challenge by chemically functionalizing non-toxic silicon nanocrystals with triplet-accepting anthracene ligands. Photoexciting these structures drives spin-triplet exciton transfer from silicon to anthracene through a single 15 ns Dexter energy transfer step with a nearly 50% yield. When paired with 9,10-diphenylanthracene emitters, these particles readily upconvert 488–640 nm photons to 425 nm violet light with efficiencies as high as 7 ± 0.9% and can be readily incorporated into aqueous micelles for biological use. Our demonstration of spin-triplet exciton transfer from silicon to molecular triplet acceptors can critically enable new technologies for solar energy conversion, quantum information and near-infrared driven photocatalysis.

Silicon-core–carbon-shell nanoparticles have been widely studied as promising candidates for the replacement of graphite in commercial lithium-ion batteries. Over more than 10 years of R&D, the many groups actively working in this field have proposed a profusion of distinctive nanomaterial designs. This broad variety makes it extremely challenging to establish mechanistic insight into how fundamental material structure and properties affect battery performance. In particular, the interplay between the character of the carbon encapsulation layer and the electrochemical performance of the composite is still poorly understood. In this work, we aim to address this lack of knowledge through the development of a modified chemical vapor deposition approach that enables precise control of the degree of graphitization of the carbon coating. We provide a comparison between core–shell structures maintaining identical silicon cores with different types of carbon shells, that is, graphitic carbon and amorphous carbon. A highly graphitic carbon layer is not only characterized by higher electrical conductivity but markedly favors the transport of lithium ions into the silicon core with respect to an amorphous one. This advantageous property confers better cycling stability to the composite material. We also demonstrate that the graphitic-carbon-coated particles display excellent electrochemical performance even when used as a simple “drop-in” additive in graphite-dominant anodes for current generation Li-ion batteries. Replacement of 10% by weight of graphite in the electrode composition results in an increase of 60% in the storage capacity with a first cycle Coulombic efficiency of 91% and capacity retention over 100 cycles of 86%.

Titanium nitride (TiN) offers advantages compared to standardly used plasmonic materials such as gold and silver in terms of thermal stability, cost, and sustainability. While gold and silver nanostructures have played an important role in the rapidly growing field of plasmonic catalysis, the potential of TiN in this application is still underexplored. Here we provide evidence of plasmon-driven chemical activity in TiN by using the photoreduction of platinum ions under visible–near-infrared (vis–NIR) illumination as probe reaction. An aqueous solution of TiN, methanol, and chloroplatinic acid (H2PtCl6) was exposed to vis–NIR radiation (600–900 nm). Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) show nanostructures composed of ∼2 nm metallic platinum clusters decorating ∼10 nm TiN nanoparticles, confirming the plasmon-driven reduction of the Pt4+ions to their metallic state. At the same time, the evolution of CO2resulting from the photooxidation of methanol is monitored via gas chromatography. The molar Pt deposition-to-CO2evolution ratio is in good agreement with the theoretical expectation based on the redox reaction charge balance. We have found that both Pt deposition and CO2evolution are self-limiting. We attribute this to the increasing plasmon dephasing rate during the photoreduction process, likely due to the high optical losses of Pt in the vis–NIR region. In addition, density functional theory (DFT) simulations of a Pt(111)–TiN(111) junction suggest the existence of an energy barrier limiting electron transfer. This work confirms that plasmonic TiN nanoparticles can use visible light to drive photochemical reactions and highlights the potential of TiN as a cost-effective alternative to gold and silver.

Nonthermal plasmas provide a unique approach to electrically driven heterogeneous catalytic processes. Despite much interest from the community, fundamental activation pathways in these processes remain poorly understood. Here, we investigate how exposure to a nonthermal plasma sustained in an argon nonreactive atmosphere affects the desorption of carbon monoxide (CO) from platinum nanoparticles. Temperature-programmed desorption measurements indicate that the plasma reduces the effective binding energy (BE) of CO to Pt surfaces by as much as ∼0.3 eV, with the reduction in the BE scaling linearly with the plasma density. We find that the effective CO BE is most strongly reduced for under-coordinated sites (steps and edges) compared to well-coordinated sites (terraces). Density functional theory calculations suggest that this is due to plasma-induced charging and electric fields at the catalyst surface, which preferentially affect under-coordinated sites. This study provides direct experimental evidence of plasma-induced nonthermal activation of the adsorbate-catalyst couple.

Measuring the contact angle at the solid/liquid/vapor triple point in sessile drop experiments is one of the most popular and simple ways to quantify the wettability of surfaces and determine the surface free energy. Despite decades of technical advancements in contact angle measurements, which allowed for improving the precision of sessile drop measurements below ±1°, an often overlooked source of experimental error in these measurements originates from the camera’s parallax angle (PA) – the angle between the camera optical axis and the sample stage surface. Here, we quantified the systematic errors in the measurement of contact angles due to the acquisition of drop images at finite PA values by simulating sessile drop experiments in which synthetic drops were created using the Young–Laplace equation. The absolute contact angle error induced by imaging drops at nonzero PAs was found to increase as the true contact angle (TCA) deviates from 90° and resulted in an overestimation (underestimation) of the contact angle for drops having TCAs lower (higher) than 90°. The computed absolute contact angle error reaches values as high as −20° (+12.2°) for drops having a TCA of 175° (5°) when imaged with a PA of 10°, thus indicating the importance of considering the PA when accurately quantifying contact angles in sessile drop experiments. The shape and, by extension, volume of the sessile drop was also found to affect the magnitude of the absolute contact angle error as sessile drops with higher apex curvatures exhibited lower absolute error than those with lower curvatures at any given PA. The outcomes of this work provide guidelines for minimizing systematic errors in sessile drop measurements due to the collection of drop images at nonzero PAs.

A non-thermal plasma method is used to synthesize plasmonic TiN nanoparticles with tunable optical properties. Nitrogen and titanium precursor gases (NH3 and TiCl4) are ionized in a quartz tube reactor. The non-equilibrium conditions in the discharge allow for the production of crystalline TiN particles with a narrow particle size distribution. Optical and surface characterizations reveal that the plasmonic performance is dependent on the particles degree of oxidation. This correlation can be controlled by modifying the NH3-to-TiCl4 ratio. We hypothesize that particle production at higher NH3 flow rates leads to a higher vacancy density that facilitates the diffusion of oxygen into the particle core.

In this contribution, we present a high-throughput method for the synthesis of titanium nitride nanoparticles. The technique, based on a continuous-flow nonthermal plasma process, leads to the formation of free-standing titanium nitride particles with crystalline structures and below 10 nm in size. Extinction measurements of the as-synthesized particles show a clear plasmonic resonance in the near-infrared region, with a peak plasmon position varying between 800 and 1000 nm. We have found that the composition can be controllably tuned by modifying the process parameters and that the particle optical properties are strongly dependent upon composition. XPS and STEM/EDS analyses suggest that nitrogen-poor particles are more susceptible to oxidation, and the extinction spectra show a decrease and a red-shift in plasmon peak position as the degree of oxidation increases. The role of oxidation is confirmed by real-time, time-dependent density functional tight binding (RT-TDDFTB) calculations, which also predict a decrease in the localized surface plasmon resonance energy when a single monolayer of oxygen is added to the surface of a titanium nitride nanocrystal. This study highlights the opportunity and challenges presented by this material system. Understanding the processing-properties relationships for alternative plasmonic materials such as titanium nitride is essential for their successful use in biomedical, photocatalytic, and optoelectronic applications.

We have performed a rigorous investigation of the structure and composition of individual grains in copper–zinc–tin–sulfide (CZTS) films realized by sulfurization of a sputtered metal stack. Although on average close to the ideal CZTS stoichiometry, elemental analysis shows significant grain-to-grain variations in composition. High-resolution Raman spectroscopy indicates that this is accompanied by grain-to-grain structural variations as well. The intensity from the 337 cm–1Raman peak, generally assigned to the kesterite phase of CZTS, remains constant over a large area of the sample. On the other hand, signals from secondary phases at 376 cm–1(copper–tin–sulfide) and 351 cm–1(zinc–sulfide) show significant variation over the same area. These results confirm the great complexity inherent to this material system. Moreover, structural and compositional variations are recognized in the literature as a factor limiting the efficiency of CZTS photovoltaic devices. This study demonstrates how a seemingly homogeneous CZTS thin film can actually have considerable structural and compositional variations at the microscale, and highlights the need for routine microscale characterization in this material system.

The hydrogenation of metal nanoparticles provides a pathway toward tuning their combustion characteristics. Metal hydrides have been employed as solid-fuel additives for rocket propellants, pyrotechnics, and explosives. Gas generation during combustion is beneficial to prevent aggregation and sintering of particles, enabling a more complete fuel utilization. Here, we discuss a novel approach for the synthesis of magnesium hydride nanoparticles based on a two-step aerosol process. Mg particles are first nucleated and grown via thermal evaporation, followed immediately by in-flight exposure to a hydrogen-rich low-temperature plasma. During the second step, atomic hydrogen generated by the plasma rapidly diffuses into the Mg lattice, forming particles with a significant fraction of MgH2. We find that hydrogenated Mg nanoparticles have an ignition temperature that is reduced by ∼200 °C when combusted with potassium perchlorate as an oxidizer, compared to the non-hydrogenated Mg material. This is due to the release of hydrogen from the fuel, jumpstarting its combustion. In addition, characterization of the plasma processes suggests that a careful balance between the dissociation of molecular hydrogen and heating of the nanoparticles must be achieved to avoid hydrogen desorption during production and achieve a significant degree of hydrogenation.

Molybdenum disulfide (MoS2) coatings have attracted widespread industrial interest owing to their excellent lubricating properties under vacuum and inert conditions. Unfortunately, the increase in MoS2interfacial shear strength following prolonged exposure to ambient conditions (a process referred to as “aging”) has resulted in reliability issues when MoS2is employed as solid lubricant. While aging of MoS2is generally attributed to physical and chemical changes caused by adsorbed water and/or oxygen, a mechanistic understanding of the relative role of these two gaseous species in the evolution of the surface chemistry of MoS2is still elusive. Additionally, remarkably little is known about the effect of thermally- and tribologically-induced microstructural variations in MoS2on the aging processes occurring in the near-surface region of the coating. Here, we employed three analytical techniques, namely, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and grazing-incidence X-ray diffraction (GIXRD), to gain insights into the aging phenomena occurring in sputtered MoS2coatings before and after tribological testing, while also evaluating the impact of thermally-induced variations in the coating structure on aging. The outcomes of XPS analyses provide evidence that a substantial surface oxidation of MoS2only takes place under humid conditions. Furthermore, the correlation of XPS, ToF-SIMS, and GIXRD results allowed for the development of a qualitative model for the impact of shear-induced microstructural variations in MoS2on the transport of water in the near-surface region of this material and on the extent of surface oxidation. These results add significantly to our understanding of the aging mechanisms of MoS2coatings used in tribological applications and their dependence on environmental conditions.

The t(12;21)(p13;q22) translocation is the most common chromosomal abnormality in pediatric leukemia. Although this rearrangement involves 2 well-characterized transcription factors, TEL and AML1, the molecular pathways affected by the result of the translocation remain largely unknown. Also in light of recent studies showing genetic and functional heterogeneities in cells responsible for cancer clone maintenance and propagation, targeting a single common deregulated pathway may be critical for the success of novel therapies. Here we describe a novel signaling pathway that is essential for oncogenic addiction in TEL-AML1 leukemia. Our data indicate a direct role for TEL-AML1, via increasing the activity of RAC1, in regulating the phosphorylation of signal transducer and activator of transcription 3 (STAT3), which results in transcriptional induction of MYC. We demonstrate that human leukemic cell lines carrying this translocation are highly sensitive to treatment with S3I-201, a specific STAT3 inhibitor, and, more interestingly, that primary human leukemic samples are also responsive to the drug in the same concentration range. Thus, STAT3 inhibition represents a promising possible therapeutic strategy for the treatment of TEL-AML1 leukemia.

Abstract

The surface reactivity of triphenyl phosphorothionate (TPPT) on air-oxidized iron surfaces under tribological conditions in the boundary-lubrication regime has been investigated by in situ attenuated total reflection (ATR) FT-IR tribometry and ex situ X-ray photoelectron spectroscopy (XPS). In situ ATR/FT-IR tribometry allowed the measurement of the friction force during the tribological tests and its correlation with ATR/FT-IR results, providing an insight into the chemical reactions taking place at the buried interface. The TPPT molecule, which did not behave as a friction-modifier additive, reacted at the air-oxidized iron surface upon tribotesting at 423 K to give pyrophosphate, organo-phosphate, and sulfate species. The oxygenated compounds produced by the oxidation of the base oil (poly-α-olefin, PAO) during the tribological tests, adsorbed onto the iron surface and reacted with it to form carbonates and carboxylates. During the tribotests, the iron coating was worn away and corroded by the aggressive species formed during the thermo-oxidative aging of PAO. This resulted in the availability of iron cations necessary for the production of orthophosphate compounds. The ATR/FT-IR results also suggested that the rate of tribofilm formation was lower than that of tribofilm removal. The ex situ XPS analysis corroborated the formation of short-chain iron polyphosphates, organo-phosphates, and iron sulfates, together with carbonates and carboxylates. Long-chain polyphosphates and sulfoxides were also generated in the boundary lubricant layers formed by TPPT at 423 K. The composition of the tribofilms formed by TPPT was found to differ significantly from that of the boundary layers generated by ZnDTP.

The surface reactivity of triphenyl phosphorothionate (TPPT) on air-oxidized iron surfaces has been studied by in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR) and ex situ X-ray photoelectron spectroscopy (XPS). The ATR/FT-IR spectra indicate that a reaction took place at 423 K on the iron-coated germanium ATR crystal with the formation of pyrophosphates, organophosphates, and sulfates. The oxidation of the base oil (poly-α-olefin, PAO) during thermal testing, leading to the production of oxygenated compounds that can adsorb onto the iron surface and react with it, resulted in the presence of carbonates and carboxylates in the film. As the heating time increased, the corrosion of the iron coating by the aggressive species formed during the thermooxidative aging of PAO provided the cations necessary for the formation of orthophosphate compounds. The subsequent ex situ XPS analysis, besides substantiating the formation of short-chain polyphosphates, organophosphates, and sulfates on the air-oxidized iron surface, indicates the presence of oxygenated organic compounds in the outermost part of the reaction layer. Modeling the ATR/FT-IR system allowed the correlation of the changes observed in the experimental ATR/FT-IR spectra with the reflectivity alterations caused by the formation of reaction products on the iron-coated germanium ATR crystal. On the basis of these findings, a mechanism for the reaction of TPPT at the oil/iron oxide interface has been proposed.

Phonon, as a momentum carrier, may play an important role in the photoluminescence of silicon nanocrystals. However, a systematic experimental study on phonon dynamics in spatially confined silicon systems remains limited. We used inelastic neutron scattering to investigate particle size, oxidation, and temperature effects on phonon dynamics of silicon nanocrystals by measuring phonon density of states of 12 and 50 nm silicon nanocrystals with several oxidation levels at different temperatures. We showed that the lattice vibrations of large silicon nanocrystals and bulk silicon are substantially different. We found that transverse acoustic phonon modes have much stronger dependences on particle size, oxidation, and temperature than optical phonon modes. We showed that the changes in phonon dynamics have the largest effect on vibrational entropy and free energy of silicon nanocrystals at intermediate temperatures. Our results shed light on phonon dynamics of silicon-based functional nanomaterials and will facilitate further investigations of electron–phonon interactions in spatially confined silicon systems.

The molecular-level orientation and structure of ionic liquids (ILs) at liquid–solid interfaces are significantly different than in the bulk. The interfacial ordering influences both IL properties, such as dielectric constants and viscosity, and their efficacy in devices, such as fuel cells and electrical capacitors. Here, we report the layered structures of four ILs on unbiased, highly ordered pyrolytic graphite (HOPG) and Pt(111) surfaces, as determined by atomic force microscopy. The ILs investigated are 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), 1-ethyl-3-methylimidazolium perfluorobutylsulfonate ([emim][C4F9SO3]), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene bis(trifluoromethylsulfonyl)imide ([MTBD][Tf2N]), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene perfluorobutylsulfonate ([MTBD][C4F9SO3]). Molecular dynamics simulations provide complementary information on the position and orientation of the ions. These ILs form a cation layer at the IL–solid interface, followed by a layer of anions. [Emim]+and [MTBD]+have similar orientations at the surface, but [MTBD]+forms a thinner layer compared to [emim]+on both HOPG and Pt(111). In addition, [Tf2N]−shows stronger interactions with Pt(111) surfaces than [C4F9SO3]−.

The profile of temperature, reagents, main reaction products, hydrocarbons and polycyclic aromatic hydrocarbons have been determined at different heights along a vertical flow reactor on which cool, blue and yellow flames of a n-heptane/oxygen/nitrogen mixture were stabilized at atmospheric pressureBecause of very large separation introduced by this vertical flow reactor in the different reaction stages and of suitable working conditions, several hydrocarbons - like vinylacetylene, benzene, toluene, xylenes, styrene, ethynylbenzene and methylnaphthalene - have been found in the blue and yellow flames by means of GC - MSThese hydrocarbons can be regarded as intermediate products in the formation of p.c.a.h. according to Badger's study in his pyrolysis experiments of several organic compoundFinally with this type of reactor it was possible to start the study of the deposition process of the polycyclic aromatic hydrocarbons and particularly of the potent carcinogens, like benz(a) anthracene and benz(a) pyrene by examining in which reactor zones, characterized by a given temperature range and by a particular soot morphology, they were collectedIt is our opinion that the physical and chemical considerations presented by this study can become very useful since much effort will have to be devoted in future to the problem of freeing the exhaust gases from polycyclic aromatic hydrocarbons.

Inhibition of stromal cell PKC-β mitigates environment-mediated drug resistance in B cell malignancies.

The aim of this study was to review emerging evidence of novel treatments for anxiety disorders. We searched PubMed and EMBASE for evidence-based therapeutic alternatives for anxiety disorders in adults, covering the past five years. Eligible articles were systematic reviews (with or without meta-analysis), which evaluated treatment effectiveness of either nonbiological or biological interventions for anxiety disorders. Retrieved articles were summarized as an overview. We assessed methods, quality of evidence, and risk of bias of the articles. Nineteen systematic reviews provided information on almost 88 thousand participants, distributed across 811 clinical trials. Regarding the interventions, 11 reviews investigated psychological or nonbiological treatments; 5, pharmacological or biological; and 3, more than one type of active intervention. Computer-delivered psychological interventions were helpful for treating anxiety of low-to-moderate intensity, but the therapist-oriented approaches had greater results. Recommendations for regular exercise, mindfulness, yoga, and safety behaviors were applicable to anxiety. Transcranial magnetic stimulation, medication augmentation, and new pharmacological agents (vortioxetine) presented inconclusive benefits in patients with anxiety disorders who presented partial responses or refractoriness to standard treatment. New treatment options for anxiety disorders should only be provided to the community after a thorough examination of their efficacy.

No relevant conflicts of interest to declare.

Background and significance:The identification of leukemia-initiating cells (LIC) in myeloid leukemias allowed for focused therapeutic approaches to prevent drug-resistance and relapse. In B cell leukemia and lymphoma, LIC occur at a high frequency (Rehe 2013), are phenotypically diverse (Aoki 2015) and can arise from any stage of B cell development (Le Viseur 2008). While self-renewal of HSCs and other organ-stem cells is regulated by a developmental hierarchy, self-renewal in the B cell lineage is induced by positive selection events, i.e. induced by antigen-receptor (BCR) signaling when B cells bind to their cognate antigen.

No relevant conflicts of interest to declare.

The single most frequent chromosomal translocation associated with childhood ALL is the t(12;21) rearrangement that creates a fusion gene between TEL (ETV6)and AML1 (RUNX1). Although TEL-AML1+patients have very good prognoses, relapses occur in up to 20% of patients and many patients face long-term side effects of chemotherapy.

Manganese-copper alloys were pulse plated from a sulfate solution with the addition of ammonium sulfate at pH 6.7. An electrochemical investigation of the Mn–Cu electrodeposition system was conducted by potentiodynamic methods. The effect of pulse-plating on cathodic efficiency, microstructure, and crystallography of the deposits was analyzed and compared with the results from continuous plating. Pulse plated coatings with short off-time were characterized by an uniform and homogeneous morphology, suitable mechanical properties, and low copper content (<5wt%). The codeposition of copper prevented the phase transformation of as-deposited ductile γ-Mnto the brittle and hard α-Mn. All the coatings exhibited a good sacrificial protection for steel in sulfate and chloride media.