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1.
J Microsc ; 295(2): 177-190, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38415368

RESUMEN

Long-term placement of facial implants requires avoiding the formation of fibrous tissue capsules around the artificial material by creating osteoconductive properties of the surface. Most promising approach is the deposition coatings made of materials very similar to bone mineral components, that is, calcium phosphates such as hydroxyapatite (HAp). As part of the research work, an innovative, cost-effective atmospheric pressure plasma deposition (APPD) system was used as a low-temperature coating technology for generating the HAp coatings deposition. Full microstructural characterisation of the coatings using SEM and TEM techniques was carried out in the work. It has been shown that the fully crystalline HAp powder undergoes a transformation during the coatings deposition and the material had a quasi-sintered structure after deposition. The crystalline phase content increased at the coating/substrate interface, while the surface of the HAp was amorphous. This is a very beneficial phenomenon due to the process of bioresorption. The amorphous phase undergoes much faster biodegradation than the crystalline one. In order to increase the bioactivity of the HAp, Zn particles were introduced on the surface of the coating. The TEM microstructural analysis in conjunction with the qualitative analysis of the EDS chemical composition showed that the binding of the Zn particles within the HAp matrix had diffusive character, which is very favourable from the point of view of the quality of the adhesion and the bioactivity of the coating. In the case of such a complex structure and due to its very porous nature, micromechanical analysis was carried out in situ in SEM, that is, by microhardness measurements of both the HAp matrix and the Zn particle. It was shown that the average value of HAp microhardness was 4.395 GPa ± 0.08, while the average value of Zn microhardness was 1.142 GPa ± 0.02.

2.
Environ Sci Technol ; 58(20): 8724-8735, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38717952

RESUMEN

Building and protecting soil organic carbon (SOC) are critical to agricultural productivity, soil health, and climate change mitigation. We aim to understand how mechanisms at the organo-mineral interfaces influence SOC persistence in three contrasting soils (Luvisol, Vertisol, and Calcisol) under long-term free air CO2 enrichment conditions. A continuous wheat-field pea-canola rotation was maintained. For the first time, we provided evidence to a novel notion that persistent SOC is molecularly simple even under elevated CO2 conditions. We found that the elevated CO2 condition did not change the total SOC content or C forms compared with the soils under ambient CO2 as identified by synchrotron-based soft X-ray analyses. Furthermore, synchrotron-based infrared microspectroscopy confirmed a two-dimensional microscale distribution of similar and less diverse C forms in intact microaggregates under long-term elevated CO2 conditions. Strong correlations between the distribution of C forms and O-H groups of clays can explain the steady state of the total SOC content. However, the correlations between C forms and clay minerals were weakened in the coarse-textured Calcisol under long-term elevated CO2. Our findings suggested that we should emphasize identifying management practices that increase the physical protection of SOC instead of increasing complexity of C. Such information is valuable in developing more accurate C prediction models under elevated CO2 conditions and shift our thinking in developing management practices for maintaining and building SOC for better soil fertility and future environmental sustainability.


Asunto(s)
Dióxido de Carbono , Carbono , Suelo , Dióxido de Carbono/química , Suelo/química , Cambio Climático
3.
Angew Chem Int Ed Engl ; 63(22): e202403421, 2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38533686

RESUMEN

Adsorptive separation of propyne/propylene (C3H4/C3H6) is a crucial yet complex process, however, it remains a great difficulty in developing porous materials that can meet the requirements for practical applications, particularly with an exceptional ability to bind and store trace amounts of C3H4. Functionalization of pore-partitioned metal-organic frameworks (ppMOFs) is methodically suited for this challenge owing to the possibility of dramatically increasing binding sites on highly porous and confined domains. We here immobilized Lewis-basic (-NH2) and Lewis-acidic (-NO2) sites on this platform. Along with an integrated nature of high uptake of C3H4 at 1 kPa, high uptake difference of C3H4-C3H6, moderated binding strength, promoted kinetic selectivity, trapping effect and high stability, the NH2-decorated ppMOF (NTU-100-NH2) can efficiently produce polymer-grade C3H6 (99.95 %, 8.3 mmol ⋅ g-1) at room temperature, which is six times more than the NO2-decorated crystal (NTU-100-NO2). The in situ infrared spectroscopy, crystallographic analysis, and sequential blowing tests showed that the densely packed amino group in this highly porous system has a unique ability to recognize and stabilize C3H4 molecules. Moving forward, the strategy of organic functionalization can be extended to other porous systems, making it a powerful tool to customize advanced materials for challenging tasks.

4.
Angew Chem Int Ed Engl ; 63(38): e202409435, 2024 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-38945832

RESUMEN

In situ analysis of Li plating/stripping processes and evolution of solid electrolyte interphase (SEI) are critical for optimizing all-solid-state Li metal batteries (ASSLMB). However, the buried solid-solid interfaces present a challenge for detection which preclude the employment of multiple analysis techniques. Herein, by employing complementary in situ characterizations, morphological/chemical evolution, Li plating/stripping dynamics and SEI dynamics were directly detected. As a mixed ionic-electronic conducting interface, Li|Li10GeP2S12 (LGPS) performed distinct interfacial morphological/chemical evolution and dynamics from ionic-conducting/electronic-isolating interface like Li|Li3PS4 (LPS), which were revealed by combination of in situ atomic force microscopy and in situ X-ray photoelectron spectroscopy. Though Li plating speed in LGPS was higher than LPS, speed of SSE decomposition was similar and ~85 % interfacial SSE turned into SEI during plating and remained unchanged in stripping. To leverage strengths of different SSEs, an LPS-LGPS-LPS sandwich electrolyte was developed, demonstrating enhanced ionic conductivity and improved interfacial stability with less SSE decomposition (25 %). Using in situ Kelvin probe force microscopy, Li-ion behavior at interface between different SSEs was effectively visualized, uncovering distribution of Li ions at LGPS|LPS interface under different potentials.

5.
Angew Chem Int Ed Engl ; 63(13): e202316837, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38315104

RESUMEN

The interfacial processes, mainly the lithium (Li) plating/stripping and the evolution of the solid electrolyte interphase (SEI), are directly related to the performance of all-solid-state Li-metal batteries (ASSLBs). However, the complex processes at solid-solid interfaces are embedded under the solid-state electrolyte, making it challenging to analyze the dynamic processes in real time. Here, using in situ electrochemical atomic force microscopy and optical microscopy, we directly visualized the Li plating/stripping/replating behavior, and measured the morphological and mechanical properties of the on-site formed SEI at nanoscale. Li spheres plating/stripping/replating at the argyrodite solid electrolyte (Li6 PS5 Cl)/Li electrode interface is coupled with the formation/wrinkling/inflating of the SEI on its surface. Combined with in situ X-ray photoelectron spectroscopy, details of the stepwise formation and physicochemical properties of SEI on the Li spheres are obtained. It is shown that higher operation rates can decrease the uniformity of the Li+ -conducting networks in the SEI and worsen Li plating/stripping reversibility. By regulating the applied current rates, uniform nucleation and reversible plating/stripping processes can be achieved, leading to the extension of the cycling life. The in situ analysis of the on-site formed SEI at solid-solid interfaces provides the correlation between the interfacial evolution and the electrochemical performance in ASSLBs.

6.
J Virol ; 96(16): e0070322, 2022 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-35920658

RESUMEN

We have established a mouse papillomavirus (MmuPV1) model that induces both cutaneous and mucosal infections and cancers. In the current study, we use this model to test our hypothesis that passive immunization using a single neutralizing monoclonal antibody can protect both cutaneous and mucosal sites at different time points after viral inoculation. We conducted a series of experiments involving the administration of either a neutralizing monoclonal antibody, MPV.A4, or control monoclonal antibodies to both outbred and inbred athymic mice. Three clinically relevant mucosal sites (lower genital tract for females and anus and tongue for both males and females) and two cutaneous sites (muzzle and tail) were tested. At the termination of the experiments, all tested tissues were harvested for virological analyses. Significantly lower levels of viral signals were detected in the MPV.A4-treated female mice up to 6 h post-viral inoculation compared to those in the isotype control. Interestingly, males displayed partial protection when they received MPV.A4 at the time of viral inoculation, even though they were completely protected when receiving MPV.A4 at 24 h before viral inoculation. We detected MPV.A4 in the blood starting at 1 h and up to 8 weeks postadministration in some mice. Parallel to these in vivo studies, we conducted in vitro neutralization using a mouse keratinocyte cell line and observed complete neutralization up to 8 h post-viral inoculation. Thus, passive immunization with a monoclonal neutralizing antibody can protect against papillomavirus infection at both cutaneous and mucosal sites and is time dependent. IMPORTANCE This is the first study testing a single monoclonal neutralizing antibody (MPV.A4) by passive immunization against papillomavirus infections at both cutaneous and mucosal sites in the same host in the mouse papillomavirus model. We demonstrated that MPV.A4 administered before viral inoculation can protect both male and female athymic mice against MmuPV1 infections at cutaneous and mucosal sites. MPV.A4 also offers partial protection at 6 h post-viral inoculation in female mice. MPV.A4 can be detected in the blood from 1 h to 8 weeks after intraperitoneal (i.p.) injection. Interestingly, males were only partially protected when they received MPV.A4 at the time of viral inoculation. The failed protection in males was due to the absence of neutralizing MPV.A4 at the infected sites. Our findings suggest passive immunization with a single monoclonal neutralizing antibody can protect against diverse papillomavirus infections in a time-dependent manner in mice.


Asunto(s)
Infecciones por Papillomavirus , Animales , Anticuerpos Monoclonales , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Femenino , Inmunización Pasiva , Masculino , Ratones , Ratones Endogámicos BALB C , Papillomaviridae , Infecciones por Papillomavirus/prevención & control
7.
Electrophoresis ; 44(9-10): 784-792, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36640139

RESUMEN

Sample injection is a critical step in a capillary electrophoresis (CE) analysis. Electrokinetic injection is the simplest approach and is often selected for implementation in portable CE instruments. However, in order to minimize the effect of sample matrix upon the results of a CE analysis, hydrodynamic injection is preferred. Although portable CE instruments with hydrodynamic injection have been reported, injection has always been performed at the grounded end of the capillary. This simplifies fluidic handling but limits coupling with electrochemical detectors and electrospray ionization-mass spectrometry (ESI-MS). We demonstrated previously that injection at the high-voltage (HV) end of the capillary could be performed using an HV-compatible rotary injection valve (fixed-volume injection). However, the mismatch between the bore sizes of the channels on the rotor-stator valve and the separation capillary caused peak tailing and undesired mixing, impairing analytical performance. In this work, we present an HV-compatible hydrodynamic injection approach that overcomes the issues associated with the fixed-volume injection approach reported previously. The performance of the CE instrument was demonstrated by analyzing a mixture of 13 amino acids by CE coupled to laser-induced fluorescence, which showed relative standard deviations for peak area and migration time below 5% and 1%, respectively, for triplicate analysis. Additionally, replicate measurements of a mixture of amino acids, peptides, nucleobases, and nucleosides by CE coupled to electrospray ionization-mass spectrometry (CE-ESI-MS) were performed to evaluate peak tailing, and results were similar to those obtained with a commercial CE-ESI-MS setup.


Asunto(s)
Hidrodinámica , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa por Ionización de Electrospray/métodos , Electroforesis Capilar/métodos , Péptidos , Aminoácidos
8.
Electrophoresis ; 44(1-2): 10-14, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-35569140

RESUMEN

Capillary electrophoresis (CE) systems have undergone extensive development for spaceflight applications. A flight-compatible high voltage power supply and the necessary voltage isolation for other energized components can be large contributors to both the volume and mass of a CE system, especially if typical high voltage levels of 25-30 kV are used. Here, we took advantage of our custom CE hardware to perform a trade study for simultaneous optimization of capillary length, high voltage level, and separation time, without sacrificing method performance. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4 D) method recently developed by our group to target inorganic cations and amino acids relevant to astrobiology was used as a test case. The results indicate that a 50 cm long capillary with 15 kV applied voltage (half of that used in the original method) can be used to achieve measurement goals while minimizing instrument size.


Asunto(s)
Electroforesis Capilar , Cationes/análisis , Electroforesis Capilar/métodos , Conductividad Eléctrica
9.
J Microsc ; 289(1): 3-19, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36150069

RESUMEN

As a result of loading with an external force during the wear process, coating deforms uniformly. After a certain limit load is exceeded, coating deformation is localised through the formation of the so-called shear bands. It has been showed experimentally the process of shear bands formation. The microstructural characterisation before and after the mechanical tests was performed using scanning and transmission electron microscopy (SEM and TEM) on cross-sections of the samples. The analysis indicated that in the case of multilayer coatings where the ratio of the metallic to the ceramic phase is 1:1, the shear bands are formed at an angle of 45°. With a greater proportion of the ceramic phase to metallic (ratio 1:2), the shear band changed the shear angle from ∼45° to ∼90°. Mechanical in situ tests were carried out in the chambers of SEM and TEM. The scratch tests in the SEM were done with the simultaneous observation of the phenomena occurring on the surface of the tested materials showed that at a scratch force of 0.04 N, the additional outer a-C:H layer was damaged, which was shown in the form of a fault in the force-displacement diagram, and in the form of splits visible in the SEM image. However, the application of this additional layer had a positive effect on the wear mechanism of the entire coating structure. The test also indicated that in the case of coatings with phases ratio 1:2 and 1:4 (metallic to ceramic), the characteristics of the brittle material were demonstrated, unlike the coating with a 1:1 phase ratio, where plastic properties predominated. However, for the 1:2 phase ratio coating, the chip was more ductile than for the chip formed when testing a 1:4 phase ratio coating. For in situ mechanical testing in the TEM, a straining holder was used. The test showed that the shear band angle for a 1:1 ratio coating has changed from 45° to 90° due to the different direction of force interaction.

10.
Anal Bioanal Chem ; 415(4): 627-637, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36504285

RESUMEN

Planar monolayer microreactor arrays (PMMRAs) make droplet-based numerical measurements and statistical analysis cheap and easy. However, PMMRAs are typically produced in complex microfluidic devices and, moreover, still requires stringent control to reduce droplet loss during heating. In this paper, a simple, reliable, and flexible method for fabricating PMMRAs in a 96-well plate is described in detail by using simple materials and low-cost equipment. The partitioned droplets spontaneously assemble into PMMRAs in the plates, and this distribution is maintained even after incubation. This is advantageous for in situ analysis based on an individual droplet in droplet digital loop-mediated isothermal amplification (ddLAMP) and does not require the transfer of positive droplets. Precise and reproducible quantification of classical swine fever virus (CSFV) extracts was executed in these PMMRAs to verify its availability. Our results demonstrate that the proposed approach not only provides a flexible and controllable execution scheme for droplet-based nucleic acid quantification in resource-limited laboratories but also opens new perspectives for numerous analytical and biochemical applications using droplets as versatile plastic microreactors.


Asunto(s)
Técnicas Analíticas Microfluídicas , Dispositivos Laboratorio en un Chip , Proyectos de Investigación
11.
Mikrochim Acta ; 190(4): 124, 2023 03 09.
Artículo en Inglés | MEDLINE | ID: mdl-36894729

RESUMEN

A surface-enhanced Raman scattering (SERS)/fluorescence dual-mode nanoprobe was proposed to assess anti-diabetic drug actions from the expression level of the epidermal growth factor receptor (EGFR), which is a significant biomarker of breast cancers. The nanoprobe has a raspberry shape, prepared by coating a dye-doped silica nanosphere with a mass of SERS tags, which gives high gains in fluorescence imaging and SERS measurement. The in situ detection of EGFR on the cell membrane surfaces after drug actions was achieved by using this nanoprobe, and the detection results agree with the enzyme-linked immunosorbent assay (ELISA) kit. Our study suggests that rosiglitazone hydrochloride (RH) may be a potential drug for diabetic patients with breast cancer, while the anti-cancer effect of metformin hydrochloride (MH) is debatable since MH slightly promotes the EGFR expression of MCF-7 cells in this study. This sensing platform endows more feasibility for highly sensitive and accurate feedback of pesticide effects at the membrane protein level.


Asunto(s)
Neoplasias de la Mama , Femenino , Humanos , Neoplasias de la Mama/tratamiento farmacológico , Ensayo de Inmunoadsorción Enzimática , Receptores ErbB , Imagen Óptica , Fluorescencia
12.
Molecules ; 28(21)2023 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-37959759

RESUMEN

Paper spray ionization mass spectrometry (PSI MS) has emerged as a notable method for the rapid analysis of biological samples. However, the typical cellulose-based paper tip is incompatible with protein detection due to the strong interaction between cellulose hydroxyl groups and proteins. In this study, we utilized a commercially available polyolefin-based synthetic paper, Teslin®, as an alternative PSI substrate for simple protein analysis. We have named this method "droplet PSI" MS, as the aqueous protein solution droplet retains its shape on the Teslin® paper tip. For droplet PSI, no further chemical pretreatment was necessary for the Teslin® substrate; the only required preparation was shaping the Teslin® paper into a triangular tip. In droplet PSI MS, protein ion signals were instantly detected from a protein solution droplet upon applying a spray solvent in situ along with high voltage (HV). When compared with conventional PSI MS, our method demonstrated superior sensitivity. The droplet PSI MS utilizing Teslin® also showcased flexibility in real-time observation of protein alterations induced by an acid additive. Additionally, the effects of spray solvent composition and the application method were discussed.


Asunto(s)
Celulosa , Papel , Espectrometría de Masas/métodos , Solventes/química , Proteínas , Espectrometría de Masa por Ionización de Electrospray/métodos
13.
Molecules ; 28(3)2023 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-36770888

RESUMEN

A novel, inexpensive and simple experimental setup for collecting µ-Raman spectra of volatile liquids in very small quantities was developed. It takes advantage of capillary forces to detain minute volatile liquid volumes. Spectra of volatile and even scattering or absorbing media can be measured more effectively. The method is used to facilitate the collection of intensity-consistent Raman spectra from a series of reference compounds present in Origanum essential oils, in order to quantify their constituents by multiple linear regression. Wild grown Origanum plants, collected from five different regions in Greece and taxonomically identified as O. onites, O. vulgare subsp. hirtum and O. vulgare subsp. vulgare, were appropriately distilled to acquire their essential oils. Comparison of the Raman results with those from headspace gas chromatography-mass spectrometry (HS GC-MS) confirmed the successful relative quantification of the most abundant essential oil constituents, highlighting the similarities and differences of the three Origanum taxa examined. Finally, it is demonstrated that directly measuring the leaf peltate glandular hairs yields exploitable results to identify the main components of the essential oil they contain, underlining the potential of in situ (field or industry) measurements utilizing microscope-equipped portable Raman spectrometers.


Asunto(s)
Aceites Volátiles , Origanum , Origanum/química , Aceites Volátiles/química , Cromatografía de Gases y Espectrometría de Masas , Hojas de la Planta/química , Grecia
14.
Sensors (Basel) ; 22(17)2022 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-36081142

RESUMEN

Reactive oxygen species (ROS) are key drivers of biogeochemical cycling while also exhibiting both positive and negative effects on marine ecosystem health. However, quantification of the ROS superoxide (O2-) within environmental systems is hindered by its short half-life. Recently, the development of the diver-operated submersible chemiluminescent sensor (DISCO), a submersible, handheld instrument, enabled in situ superoxide measurements in real time within shallow coral reef ecosystems. Here, we present a redesigned and improved instrument, DISCO II. Similar to the previous DISCO, DISCO II is a self-contained, submersible sensor, deployable to 30 m depth and capable of measuring reactive intermediate species in real time. DISCO II is smaller, lighter, lower cost, and more robust than its predecessor. Laboratory validation of DISCO II demonstrated an average limit of detection in natural seawater of 133.1 pM and a percent variance of 0.7%, with stable photo multiplier tube (PMT) counts, internal temperature, and flow rates. DISCO II can also be optimized for diverse environmental conditions by adjustment of the PMT supply voltage and integration time. Field tests showed no drift in the data with a percent variance of 3.0%. Wand tip adaptations allow for in situ calibrations and decay rates of superoxide using a chemical source of superoxide (SOTS-1). Overall, DISCO II is a versatile, user-friendly sensor that enables measurements in diverse environments, thereby improving our understanding of the cycling of reactive intermediates, such as ROS, across various marine ecosystems.


Asunto(s)
Ecosistema , Superóxidos , Arrecifes de Coral , Especies Reactivas de Oxígeno , Agua de Mar
15.
Sensors (Basel) ; 22(17)2022 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-36080913

RESUMEN

Inertial motion capture (IMC) has gained popularity in conducting ergonomic studies in the workplace. Because of the need to measure contact forces, most of these in situ studies are limited to a kinematic analysis, such as posture or working technique analysis. This paper aims to develop and evaluate an IMC-based approach to estimate back loading during manual material handling (MMH) tasks. During various representative workplace MMH tasks performed by nine participants, this approach was evaluated by comparing the results with the ones computed from optical motion capture and a large force platform. Root mean square errors of 21 Nm and 15 Nm were obtained for flexion and asymmetric L5/S1 moments, respectively. Excellent correlations were found between both computations on indicators based on L5/S1 peak and cumulative flexion moments, while lower correlations were found on indicators based on asymmetric moments. Since no force measurement or load kinematics measurement is needed, this study shows the potential of using only the handler's kinematics measured by IMC to estimate kinetics variables. The assessment of workplace physical exposure, including L5/S1 moments, will allow more complete ergonomics evaluation and will improve the ecological validity compared to laboratory studies, where the situations are often simplified and standardized.


Asunto(s)
Ergonomía , Postura , Fenómenos Biomecánicos , Humanos , Fenómenos Mecánicos , Rango del Movimiento Articular
16.
Sensors (Basel) ; 22(23)2022 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-36502218

RESUMEN

The project Lunar Volatiles Mobile Instrumentation-Extended (LUVMI-X) developed an initial system design as well as payload and mobility breadboards for a small, lightweight rover dedicated for in situ exploration of the lunar south pole. One of the proposed payloads is the Volatiles Identification by Laser Analysis instrument (VOILA), which uses laser-induced breakdown spectroscopy (LIBS) to analyze the elemental composition of the lunar surface with an emphasis on sampling regolith and the detection of hydrogen for the inference of the presence of water. It is designed to analyze targets in front of the rover at variable focus between 300 mm and 500 mm. The spectrometer covers the wavelength range from 350 nm to 790 nm, which includes the hydrogen line at 656.3 nm as well as spectral lines of most major rock-forming elements. We report here the scientific input that fed into the concept and design of the VOILA instrument configuration for the LUVMI-X rover. Moreover, we present the measurements performed with the breadboard laboratory setup for VOILA at DLR Berlin that focused on verifying the performance of the designed LIBS instrument in particular for the detection and quantification of hydrogen and other major rock forming elements in the context of in situ lunar surface analysis.


Asunto(s)
Rayos Láser , Luna , Análisis Espectral/métodos , Agua , Hidrógeno
17.
Nano Lett ; 21(6): 2487-2496, 2021 Mar 24.
Artículo en Inglés | MEDLINE | ID: mdl-33661650

RESUMEN

Hot-injection synthesis is renowned for producing semiconductor nanocolloids with superb size dispersions. Burst nucleation and diffusion-controlled size focusing during growth have been invoked to rationalize this characteristic yet experimental evidence supporting the pertinence of these concepts is scant. By monitoring a CdSe synthesis in-situ with X-ray scattering, we find that nucleation is an extended event that coincides with growth during 15-20% of the reaction time. Moreover, we show that size focusing outpaces predictions of diffusion-limited growth. This observation indicates that nanocrystal growth is dictated by the surface reactivity, which drops sharply for larger nanocrystals. Kinetic reaction simulations confirm that this so-called superfocusing can lengthen the nucleation period and promote size focusing. The finding that narrow size dispersions can emerge from the counteracting effects of extended nucleation and reaction-limited size focusing ushers in an evidence-based perspective that turns hot injection into a rational scheme to produce monodisperse semiconductor nanocolloids.

18.
Angew Chem Int Ed Engl ; 61(21): e202117270, 2022 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-35128778

RESUMEN

Mechanochemical transformations offer environmentally benign synthesis routes, whilst enhancing both the speed and selectivity of reactions. In this regard, mechanochemistry promises to transform the way in which chemistry is done in both academia and industry but is greatly hindered by a current lack of mechanistic understanding. The continued development and use of time-resolved in situ (TRIS) approaches to monitor mechanochemical reactions provides a new dimension to elucidate these fascinating transformations. We here discuss recent trends in method development that have pushed the boundaries of mechanochemical research. New features of mechanochemical reactions obtained by TRIS techniques are subsequently discussed, which sheds light on how different TRIS approaches have been used. Emphasis is placed on the strength of combining complementary techniques. Finally, we outline our views on the potential of TRIS methods in mechanochemical research, towards establishing a new, environmentally benign paradigm in the chemical sciences.

19.
Angew Chem Int Ed Engl ; 61(47): e202212676, 2022 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-36193684

RESUMEN

Electrochemical nitrogen reduction reaction (NRR) under ambient conditions has attracted considerable scientific and engineering interest as a green alternative route for NH3 production. Molybdenum is a promising candidate as an electrocatalyst for NRR as it has a suitable binding strength with N species. However, the design of an efficient Mo-based catalyst remains elusive. To enhance the selectivity of NRR toward NH3 , we have developed a carbon nanofiber catalyst embedded with molybdenum and cobalt (Co-Mo-CNF). Co with a strong ability to dissociate water enhances local proton source near Mo, where the hydrogenation step of the NRR occurs. A NH3 formation rate of 72.72 µg h-1 mg-1 and a Faradaic efficiency of 34.5 % were obtained at -0.5 V vs. RHE. We also attempted to provide a mechanistic understanding of the NRR via in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and isotopic labeling experiments using 15 N2 and D2 O.

20.
Small ; 17(38): e2101857, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34350696

RESUMEN

Although organosulfur compounds can protect lithium anodes, participate in the redox reaction, and suppress the shuttle effect, the sluggish electrochemical dynamics of their bulk structure and the notorious shuttle effect of covalent long-chain sulfurs largely impede their actual applications. Herein, sulfurized carbon nanotube@aminophenol-formaldehyde (SC@A) with covalently linked short-chain sulfurs is firstly synthesized by in situ polymerization of aminophenol-formaldehyde (AF) on the surface of carbon nanotubes (CNTs) followed by acetone etching and inverse sulfurization processes, forming mesoporous yolk-shell organosulfur nanotubes with abundant internal joints between the yolk of CNTs and the shell of sulfurized AF for the first time. In situ Raman spectra, in situ XRD patterns, and ex situ XPS spectra verify that the covalent short-chain sulfurs bring about a reversible solid-solid conversion process of sulfur, thoroughly avoiding the shuttle effect. The mesoporous yolk-shell structure with abundant internal joints can effectively accommodate the volume change, fully expose active sites and efficiently improve the transport of electrons and lithium ions, thus highly promoting the solid-solid electrochemical reaction kinetics. Therefore, the SC@A cathode exhibits a superior specific capacity of 841 mAh g-1 and a capacity decay of 0.06% per cycle within 500 cycles at a large current density of 5.0 C.

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