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1.
Proc Natl Acad Sci U S A ; 120(12): e2219950120, 2023 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-36913567

RESUMO

High areal capacitance for a practical supercapacitor electrode requires both large mass loading and high utilization efficiency of electroactive materials, which presents a great challenge. Herein, we demonstrated the unprecedented synthesis of superstructured NiMoO4@CoMoO4 core-shell nanofiber arrays (NFAs) on a Mo-transition-layer-modified nickel foam (NF) current collector as a new material, achieving the synergistic combination of highly conductive CoMoO4 and electrochemical active NiMoO4. Moreover, this superstructured material exhibited a large gravimetric capacitance of 1,282.2 F/g in 2 M KOH with a mass loading of 7.8 mg/cm2, leading to an ultrahigh areal capacitance of 10.0 F/cm2 that is larger than any reported values of CoMoO4 and NiMoO4 electrodes. This work provides a strategic insight for rational design of electrodes with high areal capacitances for supercapacitors.

2.
Proc Natl Acad Sci U S A ; 119(20): e2202202119, 2022 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-35533280

RESUMO

SignificanceIn recent years, lithium-ion batteries (LIBs) have been widely applied in electric vehicles as energy storage devices. However, it is a great challenge to deal with the large number of spent LIBs. In this work, we employ a rapid thermal radiation method to convert the spent LIBs into highly efficient bifunctional NiMnCo-activated carbon (NiMnCo-AC) catalysts for zinc-air batteries (ZABs). The obtained NiMnCo-AC catalyst shows excellent electrochemical performance in ZABs due to the unique core-shell structure, with face-centered cubic Ni in the core and spinel NiMnCoO4 in the shell. This work provides an economical and environment-friendly approach to recycling the spent LIBs and converting them into novel energy storage devices.

3.
Small ; : e2400652, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38552224

RESUMO

Designing a reasonable heterojunction is an efficient path to improve the separation of photogenerated charges and enhance photocatalytic activity. In this study, Cu2-xS@NiFe-LDH hollow nanoboxes with core-shell structure are successfully prepared. The results show that Cu2-xS@NiFe-LDH with broad-spectrum response has good photothermal and photocatalytic activity, and the photocatalytic activity and stability of the catalyst are enhanced by the establishment of unique hollow structure and core-shell heterojunction structure. Transient PL spectra (TRPL) indicates that constructing Cu2-xS@NiFe-LDH heterojunction can prolong carrier lifetime obviously. Cu2-xS@NiFe-LDH shows a high photocatalytic hydrogen production efficiency (5176.93 µmol h-1 g-1), and tetracycline degradation efficiency (98.3%), and its hydrogen production rate is ≈10-12 times that of pure Cu2-xS and NiFe-LDH. In situ X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) provide proofs of the S-scheme electron transfer path. The S-scheme heterojunction achieves high spatial charge separation and exhibits strong photoredox ability, thus improving the photocatalytic performance.

4.
Small ; : e2401335, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38693088

RESUMO

Exploration of multifunctional integrated catalysts is of great significance for photocatalysis toward practical application. Herein, a 1D confined nanoreactor with a heterogeneous core-shell structure is designed for synergies of efficient catalysis and temperature monitoring by custom encapsulation of Z-scheme heterojunction CuS quantum dots/BiVO4 (CuS QDs/BiVO4) and Y2O2S-Er, Yb. The dispersed active sites created by the QDs with high surface energy improve the mass transfer efficiency, and the efficient electron transport channels at the heterogeneous interface extend the carrier lifetime, which endows the nanoreactor with excellent catalytic performance. Meanwhile, real-time temperature monitoring is realized based on the thermally coupled levels 2H11/2/4S3/2→4I15/2 of Er3+ using fluorescence intensity ratio, which enables the monitorable photocatalysis. Furthermore, the nanoreactor with a multidimensional structure increases effective intermolecular collisions to facilitate the catalytic process by restricting the reaction within distinct enclosed spaces and circumvents potential unknown interaction effects. The design of multi-space nanoconfined reactors opens up a new avenue to modulate catalyst function, providing a unique perspective for photocatalytic applications in the mineralization of organic pollutants, hydrogen production, and nitrogen fixation.

5.
Small ; 20(24): e2306447, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38152988

RESUMO

Due to their anisotropy, 1D semiconductor nanorod-based materials have attracted much attention in the process of hydrogen production by solar energy. Nevertheless, the rational design of 1D heterojunction materials and the modulation of photo-generated electron-hole transfer paths remain a challenge. Herein, a ZnxCd1-xS@ZnS/MoS2 core-shell nanorod heterojunction is precisely constructed via in situ growth of discontinuous ZnS shell and MoS2 NCs on the Zn─Cd─S nanorods. Among them, the Zn vacancy in the ZnS shell builds the defect level, and the nanoroelded MoS2 builds the electron transport site. The optimized photocatalyst shows significant photocatalytic activity without Platinum as an auxiliary catalyst, mainly due to the new interfacial charge transfer channel constructed by the shell vacancy level, the vertical separation and the de-accumulation process of photo-generated electrons and photo-generated holes. At the same time, spectral analysis, and density functional theory (DFT) calculations fully prove that shortening difference of speed between the photogenerated electron and hole movement process is another key factor to enhance the photocatalytic performance. This study provides a new path for the kinetic design of enhanced carrier density by shortening the carrier retention time of 1D heterojunction photocatalysts with improved photocatalytic performance.

6.
Small ; 20(23): e2310040, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38150619

RESUMO

Constructing composite catalysts with refined geometric control and optimal electronic structure provides a promising route to enhance electrocatalytic performance toward the oxygen evolution reaction (OER). Herein, a composite catalyst is prepared with multiple components using chemical vapour deposition method to transform crystalline NiFe2O4 into crystalline NiFe2O4@amorphous S-NiFe2O4 with core-shell structure (C-NiFe2O4@A-S-NiFe2O4), and Fe-NiOOH nanoparticles are subsequently in situ generated on its surface during the process of electrocatalytic OER. The C-NiFe2O4@A-S-NiFe2O4 catalyst exhibits a low overpotential of 275 mV while possessing an excellent stability for 500 h at 10 mA cm-2. The anion exchange membrane water electrolyzer with C-NiFe2O4@A-S-NiFe2O4 anode catalyst obtains a current density of 4270 mA cm- 2 at 2.0 V. Further, in situ Raman spectroscopy result demonstrates that in situ generated Fe-NiOOH nanoparticles are revealed to act as the catalytic active phase for catalyzing the OER. Besides, introducing A-S-NiFe2O4 in C-NiFe2O4@A-S-NiFe2O4 facilitates the formation of Fe-NiOOH nanoparticles with high-valency Ni, thus increasing the proportion of lattice oxygen-participated OER. This work not only provides an alternative strategy for the design of high-performance catalysts, but also lays a foundation for the exploration of catalytic mechanisms.

7.
Small ; 20(23): e2310318, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38183374

RESUMO

Low-cost and high-efficiency non-precious metal-based oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalysts are the key to promoting the commercial application of metal-air batteries. Herein, a highly efficient catalyst of Fe0.18Co0.82 alloy anchoring on the nitrogen-doped porous carbon hollow sphere (FexCo1-x/N-C) is intelligently designed by spray pyrolysis (SP). The zinc in the SP-derived metal oxides and metal-organic framework volatilize at high temperature to construct a hierarchical porous structure with abundant defects and fully exposes the FeCo nanoparticles which uniformly anchor on the carbon substrate. In this structure, the coexistence of Fe0.18Co0.82 alloy and binary metal active sites (Fe-Nx/Co-Nx) guarantees the Fe0.2Co0.8/N-C catalyst exhibiting an excellent half-wave potential (E1/2 ═ 0.84 V) superior to 20% Pt/C for ORR and a suppressed overpotential (280 mV) than RuO2 for OER. Assembled rechargeable Zn-air battery (RZAB) demonstrates a promising specific capacity of 807.02 mAh g-1, peak power density of 159.08 mW cm-2 and durability without electrolyte circulation (550 h). This work proposes the design concept of utilizing an oxide core to in situ consume the porous carbon shell for anchoring metal active sites and construct defects, which benefits from spray pyrolysis in achieving precise control of the alloy structure and mass preparation.

8.
Small ; 20(26): e2310970, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38243848

RESUMO

Hypergolicity is a highly desired characteristic for hybrid rocket engine-based fuels because it eliminates the need for a separate ignition system. Introducing hypergolic additives into conventional fuels through physical mixing is a feasible approach, but achieving highly reliable hypergolic ignition and energy release remains a major challenge. Here, the construction of core-shell Al@metal organic framework (MOF) heterostructures is reported as high-performance solid hypergolic propellants. Upon contact with the liquid oxidizer the uniformly distributed hypergolic MOF (Ag-MOF) shell can induce the ignition of hypergolic-inert fuel Al, resulting in Al combustion. Such a synthetic strategy is demonstrated to be favorable in hotspot generation and heat transfer relative to a simple physical mixture of Al/Ag-MOF, thus producing shorter ignition delay times and more efficient combustion. Thermal reactivity study indicated that the functionalization of the Ag-MOF shell changes the energy release process of the inner Al, which is accompanied by a thermite reaction. The synergistic effect of implantation of hypergolic MOF and high energy Al contributes to high specific impulses of 230-270 s over a wide range of oxidizer-to-fuel ratios.

9.
Small ; : e2400518, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38747079

RESUMO

Motivated by the increasing cost, environmental concerns, and limited availability of Co, researchers are actively seeking alternative cathode materials for lithium-ion batteries. A promising strategy involves structure-modified materials, such as a NiMn core/shell system. This design leverages the high energy density of a Ni-rich core while employing an Mn-rich shell to enhance interfacial stability by suppressing unwanted reactions with the electrolyte. This approach offers improved cycling stability and reduced reliance on Co. However, the interdiffusion of Mn ions between the core and shell remains a significant challenge during synthesis. This work presents a facile approach to address the issue of Mn interdiffusion in core/shell cathode materials. The study demonstrates that partial oxidation of the precursor during the drying stage effectively enhances the Mn oxidation state. This strategy successfully suppresses Mn interdiffusion during subsequent calcination, leading to the preservation of the core/shell architecture in the final cathode material. This optimized structure mitigates interfacial reactions, enhances chemomechanical properties, and reduces crosstalk, a major contributor to rollover failure. This work presents a novel approach for synthesizing high-performance core/shell cathode materials for next-generation lithium-ion batteries.

10.
Small ; 20(28): e2309750, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38299490

RESUMO

Nanoarchitectonics of semiconductors shed light on efficient photocatalytic hydrogen evolution by precisely controlling the surface microenvironment of cocatalysts. Taking cadmium zinc sulfide (CZS) nanoparticles as a target, the spontaneous modifications are conducted by interactions between surface Cd2+/Zn2+ atoms and thiol groups in thioglycolic acid. The capping ligand impacts the semiconductor surface with a negative electronic environment, contributing to the full coverage of CZS by nickel-cobalt hydroxides (NiCo-LDHs) cocatalysts. The obtained core-shell CZS@NiCo-LDHs, possessing a shell thickness of ≈20 nm, exhibits a distinguished topology (SBET = 87.65m2 g-1), long surface carrier lifetime, and efficient charge-hole separation. Further photocatalytic hydrogen evaluation demonstrates an enhanced H2 evolution rate of 18.75 mmol g-1 h-1 with an apparent quantum efficiency of 16.3% at 420 nm. The recorded catalytic performance of the core-shell sample is 44.6 times higher than that of pure CZS nanospheres under visible light irradiation. Further density functional theory simulations indicate that sulfur atoms play the role of charge acceptor and surface Ni/Co atoms are electron donors, as well as a built-in electric field effect can be established. Altogether, this work takes advantage of strong S affinity from surface metal atoms, revealing the interfacial engineering toward improved visible-light-driven photocatalytic hydrogen evolution (PHE) activity.

11.
Small ; : e2311504, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38412431

RESUMO

Herein, guided by the results of density functional theory prediction, the study rationally designs a hollow core-shell FeNi2 S4 @ZnIn2 S4 (FNS@ZIS) Step-scheme (S-scheme) heterojunction for photocatalytic H2 evolution with photothermal-assisted. The hollow FNS spheres offered substrate for coating the ZIS nanosheets, which can inhibit ZIS nanosheets from agglomerating into pellet, enrich the active site, increase specific surfaces, and raise the light absorption. Notably, due to its excellent photothermal properties, FNS core generated heat unceasingly inside under visible-light irradiation and effectively prevent the heat loss of the reaction system, which increased the local temperature of photocatalysts and thus accelerated the charge migration. In addition, the S-scheme heterojunction construction via in situ growth has a tight interface, which can facilitate the separation and transfer of carriers and achieve high redox potential. Owning to the distinctive construction, the hollow core-shell FNS@ZIS S-scheme heterojunction show extraordinary stability and photocatalytic H2 evolution rate with 7.7 mmol h-1  g-1 , which is ≈15.2-fold than pristine ZIS. Based on the double evidence of theoretical predictions and experimental confirmations, the photothermal effect and electron transfer mechanism of this innovative material are investigated in depth by the following infrared thermography technology and deep DFT calculations.

12.
Small ; : e2311312, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38566552

RESUMO

The exploitation of multicomponent composites (MCCs) has become the main pathway for obtaining advanced microwave absorption materials (MAMs). Herein, a metal valence state modulation strategy is proposed to tune the electromagnetic (EM) parameters and improve microwave absorption performances. Core@shell hollow carbon microspheres@MoSe2 and hollow carbon microspheres@MoSe2/MoOx MCCs with various mixed-valence states content are well-designed and produced by a simple hydrothermal reaction or/and heat treatment process. The results reveal that the thermal treatment of hollow carbon microspheres@MoSe2 in Ar and Ar/H2 leads to the in situ formation of MoOx and multivalence state, respectively, and the enhanced content of Mo4+ in the designed MCCs greatly boosts their impedance matching characteristics, polarization, and conduction loss capacities, which lead to their evidently improved EM wave absorption properties. Amongst, the as-prepared hollow carbon microspheres@MoSe2/MoOx MCCs achieve an effective absorption bandwidth of 5.80 GHz under a matching thickness of 1.97 mm and minimum reflection loss of -21.49 dB. Therefore, this work offers a simple and universal method to fabricate core@shell hollow carbon microspheres@MoSe2/MoOx MCCs, and a novel and feasible metal valence state modulation strategy is proposed to develop high-efficiency MAMs.

13.
Chembiochem ; : e202400406, 2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38850275

RESUMO

The use of traditional Ag-based antibacterial agents is usually accompanied by uncontrollable silver release, which makes it difficult to find a balance between antibacterial performance and biosafety. Herein, we prepared a core-shell system of ZIF-8-derived amorphous carbon-coated Ag nanoparticles (Ag@C) as an ideal research model to reveal the synergistic effect and structure-activity relationship of the structural transformation of carbon shell and Ag core on the regulation of silver release behavior. It is found that Ag@C prepared at 600 °C (AC6) exhibits the best ion release kinetics due to the combination of relatively simple shell structure and lower crystallinity of Ag core, thereby exerting stronger antibacterial properties (> 99.999%) at trace doses (20 µg mL-1) compared with most other Ag-based materials. Meanwhile, the carbon shell prevents the metal Ag from being directly exposed to the organism and thus endows AC6 with excellent biocompatibility. In animal experiments, AC6 can effectively promote wound healing by inactivating drug-resistant bacteria while regulating the expression of TNF-α and CD31. This work provides theoretical support for the scientific design and clinical application of controllable ion-releasing antibacterial agents.

14.
Nanotechnology ; 35(22)2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38470062

RESUMO

In this study, S-CCO@Co(OH)2('CCO' representing CuCo2O4/Cu2O; 'S-'representing sulfur doping) was synthesized by hydrothermal method followed by electrodeposition. The multiple effects of S doping were studied by S doping and constructing 3D core-shell structure. S doping induced the reduction of Cu2+and Co3+to Cu+and Co2+, respectively. Also, S partially replaces O and creates oxygen vacancies, which increases a number of active sites for the redox reaction enhancing the redox reaction activity. After the electrodeposition, S-Co bond is formed between the Co(OH)2shell and the S-CCO core, which suggests a synergistic effect between S doping and core-shell structure. The formation of S-Co bond is conducive to electron and ion transport, thus improving electrochemical performance. After modification, the specific capacitance of S-CCO@Co(OH)2is 4.28 times higher than CCO, up to 1730 Fg-1. Furthermore, the assembled S-CCO@Co(OH)2//activated carbon supercapacitor exhibits an energy density of 83.89 Whkg-1at 848.81 Wkg-1and a retention rate of 98.48% after 5000 charge and discharge cycles. Therefore, S doping and its mutual effect with the utilization of the core-shell structure considerably enhanced the electrochemical performance of the CCO-based electrodes, endowing its potential in further application.

15.
Nanotechnology ; 35(12)2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38096572

RESUMO

Due to the unique physicochemical properties of gold nanoparticles (AuNPs) decorated silica nanostructures (SiO2@AuNPs), they show great potential for applications in catalysis, biosensing, optical devices and medicine. It is essential to explore the catalytic effect of SiO2@AuNPs and the understanding of the essential process of catalytic reactions. We have prepared SiO2@AuNPs by loading small-sized AuNPs on surface-modified silica nanospheres. SiO2@AuNPs was used as a catalyst for the catalytic reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4, and the results showed that with the increase of the amount of catalyst from 30 to 100µl, the corresponding rate constantKappwas increased from 6.44 × 10-3to 1.45 × 10-2s-1, and its TOF was as high as 1.326 × 103h-1, and the catalytic rate could still be maintained at 87% after five cycles. By analyzing the morphology and size of the SiO2supported AuNPs before and after the catalytic reaction, it can be seen that the atoms on the surface of small-sized AuNPs supported by silica have migrated during the catalytic process, which subsequently affects the catalytic efficiency of the structure. This study proves the good catalytic effect of SiO2@AuNPs structure and lays the foundation for its wider application.

16.
Nanotechnology ; 35(33)2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38763132

RESUMO

Novel nanocomposites of poly (ether-ketone) (PEK) reinforced with carbon-coated Nickel nanoparticles (CCNi) were synthesized through a sequential process involving cost-effective ball milling and hot compaction. Scanning electron microscopy revealed an excellent dispersion and a three-dimensional network of CCNi nanoparticles in the matrix, causing a significant improvement in the electrical conductivity and electromagnetic interference shielding effectiveness (SE). Carbon coating of about 5 nm thick over Ni nanoparticle probably helps in uniform dispersion, avoids its oxidation and reduces its agglomeration in the matrix. An exceptionally low percolation threshold of 2.1 vol.% CCNi was found, and eight-orders of magnitude enhancement in the dc-electrical conductivity was achieved. The highest dc- and ac-electrical conductivities achieved were more than 0.01 S cm-1at 5.89 vol.% CCNi nanoparticles content which were the highest values amongst reported Ni-filled polymer composites and comparable with those of carbon nanotubes filled PEK nanocomposites. Electromagnetic interference SE of the CCNi/PEK nanocomposites was measured in the X-band, and a total SE (SET) of 17.52 dB was obtained for 5.89 vol.% CCNi reinforced PEK nanocomposite.

17.
J Sep Sci ; 47(11): e2300915, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38847294

RESUMO

In this work, core-shell material with a special structure was designed and applied in solid-phase extraction (SPE) for non-steroidal anti-inflammatory drugs (NSAIDs) combined with high-performance liquid chromatography. Based on the advantages of core-shell ZIF-8@ZIF-67 (Zeolite imidazole ester framework materials [ZIFs]), effective derivatization treatment was carried out to partially vulcanize the original ZIFs, resulting in a special and new double-core-shell structural material CoS/ZIF-67/ZnS/ZIF-8 (ZIFs@ZnS@CoS) with porous surface and center hollow. The multiple forces caused by the rich chemical structure, the large specific surface area caused by the special pore structure, and the effective protection of the ZIFs core by sulfide shell make the designed material have higher extraction efficiency and longer service life, compared with ZIF-8@ZIF-67 and ZIF-8. At the same time, the established analytical method for non-steroidal drugs had a high recovery rate (98.93%-102.10%), low detection limit (0.11-0.27 µg/L), and wide linear range (1-200 µg/L) within a good correlation coefficient R2 (0.9978-0.9993). Satisfactory results were also obtained from the extraction of NSAIDs from the Yellow River water samples. These results indicate that the designed double-core-shell structure material can effectively exert its structural advantages and become a promising extraction material.


Assuntos
Anti-Inflamatórios não Esteroides , Extração em Fase Sólida , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/isolamento & purificação , Anti-Inflamatórios não Esteroides/análise , Extração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão , Propriedades de Superfície , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/análise , Tamanho da Partícula , Estruturas Metalorgânicas/química , Estrutura Molecular , Porosidade , Zeolitas/química , Adsorção , Imidazóis/química
18.
Molecules ; 29(8)2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38675517

RESUMO

It is imperative to develop an efficient catalyst to reduce the energy barrier of electrochemical water decomposition. In this study, a well-designed electrocatalyst featuring a core-shell structure was synthesized with cobalt sulfides as the core and molybdenum disulfide nanosheets as the shell. The core-shell structure can prevent the agglomeration of MoS2, expose more active sites, and facilitate electrolyte ion diffusion. A CoS2/MoS2 heterostructure is formed between CoS2 and MoS2 through the chemical interaction, and the surface chemistry is adjusted. Due to the morphological merits and the formation of the CoS2/MoS2 heterostructure, CoS2@MoS2 exhibits excellent electrocatalytic performance during the oxygen evolution reaction (OER) process in an alkaline electrolyte. To reach the current density of 10 mA cm-2, only 254 mV of overpotential is required for CoS2@MoS2, which is smaller than that of pristine CoS2 and MoS2. Meanwhile, the small Tafel slope (86.9 mV dec-1) and low charge transfer resistance (47 Ω) imply the fast dynamic mechanism of CoS2@MoS2. As further confirmed by cyclic voltammetry curves for 1000 cycles and the CA test for 10 h, CoS2@MoS2 shows exceptional catalytic stability. This work gives a guideline for constructing the core-shell heterostructure as an efficient catalyst for oxygen evolution reaction.

19.
AAPS PharmSciTech ; 25(3): 58, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38472689

RESUMO

Hydrocortisone (HC) is the optimal drug for adolescents diagnosed with congenital adrenal hyperplasia (CAH). Because traditional dosage regimens HC are inconvenient, our study used fused deposition modeling (FDM) three-dimensional (3D) printing technology to solve the problems caused by traditional preparations. First, we designed a core-shell structure tablet with an inner instant release component and an outer delayed release shell. The instant release component was Kollicoat IR: glycerol (GLY): HC = 76.5:13.5:10. Then, we used Affinisol® HPMC 15LV to realize delayed release. Furthermore, we investigated the relationship between the thickness of the delayed release shell and the delayed release time, and an equation was derived through binomial regression analysis. Based on that equation, a novel triple pulsatile tablet with an innovative structure was devised. The tablet was divided into three components, and the drug was released multiple times at different times. The dose and release rate of the tablets can be adjusted by modifying the infill rate of the printing model. The results indicated that the triple pulsatile tablet exhibited desirable release behavior in vitro. Moreover, the physicochemical properties of the drug, excipients, filaments, and tablets were characterized. All these results indicate that the FDM 3D printing method is a convenient technique for producing preparations with intricate structures.


Assuntos
Hidrocortisona , Impressão Tridimensional , Liberação Controlada de Fármacos , Comprimidos/química , Tecnologia Farmacêutica/métodos
20.
J Environ Sci (China) ; 141: 40-50, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38408833

RESUMO

The Tibetan Plateau, known as the "Third Pole", is currently in a state of perturbation caused by intensified human activity. In this study, 56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS, STXM, and NEXAFS spectroscopy. After careful examination of 3387 single particles, the results showed that Fe should be one of the most frequent metal elements. The Fe-containing single particles in irregular shape and micrometer size was about 7.8% and might be mainly from local sources. Meanwhile, the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide. Interestingly, the core-shell structure of iron-containing particles were about 38.8% and might be present as single-, dual- or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5, 10.5, 2.9 and 1.2, respectively. Meanwhile, iron and manganese were found to coexist with identical distributions in the single particles, which might induce a synergistic effect between iron and manganese in catalytic oxidation. Finally, the solid spherical structure of Fe-containing particles without an external layer were about 53.4%. The elements of Fe and Mn were co-existed, and might be presented as iron oxide-manganese oxide-silica composite. Moreover, the ferrous and ferric forms of iron might be co-existed. Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere.


Assuntos
Compostos Férricos , Ferro , Manganês , Humanos , Ferro/química , Tibet , Microscopia Eletrônica de Transmissão
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