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1.
Adv Mater ; : e1907041, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32449197

RESUMO

Transition metal dichalcogenide (TMDCs) alloys could have a wide range of physical and chemical properties, ranging from charge density waves to superconductivity and electrochemical activities. While many exciting behaviors of unary TMDCs have been demonstrated, the vast compositional space of TMDC alloys has remained largely unexplored due to the lack of understanding regarding their stability when accommodating different cations or chalcogens in a single-phase. Here, a theory-guided synthesis approach is reported to achieve unexplored quasi-binary TMDC alloys through computationally predicted stability maps. Equilibrium temperature-composition phase diagrams using first-principles calculations are generated to identify the stability of 25 quasi-binary TMDC alloys, including some involving non-isovalent cations and are verified experimentally through the synthesis of a subset of 12 predicted alloys using a scalable chemical vapor transport method. It is demonstrated that the synthesized alloys can be exfoliated into 2D structures, and some of them exhibit: i) outstanding thermal stability tested up to 1230 K, ii) exceptionally high electrochemical activity for the CO2 reduction reaction in a kinetically limited regime with near zero overpotential for CO formation, iii) excellent energy efficiency in a high rate Li-air battery, and iv) high break-down current density for interconnect applications. This framework can be extended to accelerate the discovery of other TMDC alloys for various applications.

2.
J Mol Cell Biol ; 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32236479

RESUMO

The islet of Langerhans produces endocrine hormones to regulate glucose homeostasis. The normal function of the islet relies on the homeostatic regulations of cellular composition and cell-cell interactions within the islet microenvironment. Immune cells populate the islet during embryonic development and participate in islet organogenesis and function. In obesity, a low-grade inflammation manifests in multiple organs, including pancreatic islets. Obesity-associated islet inflammation is evident in both animal models and humans, characterized by the accumulation of immune cells and elevated production of inflammatory cytokines/chemokines and metabolic mediators. Myeloid-lineage cells (monocytes and macrophages) are the dominant type of immune cells in islet inflammation during the development of obesity and type 2 diabetes mellitus (T2DM). In this review, we will discuss the role of immune system in islet homeostasis and inflammation and summarize recent findings of the cellular and molecular factors that alter islet microenvironment and ß cell function in obesity and T2DM.

3.
J Inorg Biochem ; 206: 110997, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32169780

RESUMO

Several studies have focused on the antimicrobial effects of cerium oxide nanoparticles (CeO2-NP) but few have focused on their effects on bacteria under initial biofilm formation conditions. Streptococcus mutans is a prolific biofilm former contributing to dental caries in the presence of fermentable carbohydrates and is a recognized target for therapeutic intervention. CeO2-NP derived solely from Ce(IV) salt hydrolysis were found to reduce adherent bacteria by approximately 40% while commercial dispersions of "bare" CeO2-NP (e.g., 3 nm, 10-20 nm, 30 nm diameter) and Ce(NO3)3·6H2O were either inactive or observed to slightly increase biofilm formation under similar in vitro conditions. Planktonic growth and dispersal assays support a non-bactericidal mode of biofilm inhibition active in the initial phases of S. mutans biofilm production. Human cell proliferation assays suggest only minor effects of hydrolyzed Ce(IV) salts on cellular metabolism at concentrations up to 1 mM Ce, with less observed toxicity compared to equimolar concentrations of AgNO3. The results presented herein have implications in clinical dentistry.

4.
J Am Chem Soc ; 141(34): 13487-13496, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31379152

RESUMO

In contrast to molecular systems, which are defined with atomic precision, nanomaterials generally show some heterogeneity in size, shape, and composition. The sample inhomogeneity translates into a distribution of energy levels, band gaps, work functions, and other characteristics, which detrimentally affect practically every property of functional nanomaterials. We discuss a novel synthetic strategy, colloidal atomic layer deposition (c-ALD) with stationary reactant phases, which largely circumvents the limitations of traditional colloidal syntheses of nano-heterostructures with atomic precision. This approach allows for significant reduction of inhomogeneity in nanomaterials in complex nanostructures without compromising their structural perfection and enables the synthesis of epitaxial nano-heterostructures of unprecedented complexity. The improved synthetic control ultimately enables bandgap and strain engineering in colloidal nanomaterials with close to atomic accuracy. To demonstrate the power of the new c-ALD method, we synthesize a library of complex II-VI semiconductor nanoplatelet heterostructures. By combining spectroscopic and computational studies, we elucidate the subtle interplay between quantum confinement and strain effects on the optical properties of semiconductor nanostructures.

5.
ACS Nano ; 13(3): 3730-3738, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30807693

RESUMO

Strain engineering of semiconductors is used to modulate carrier mobility, tune the energy bandgap, and drive growth of self-assembled nanostructures. Understanding strain-energy relaxation mechanisms including phase transformations, dislocation nucleation and migration, and fracturing is essential to both exploit this degree of freedom and avoid degradation of carrier lifetime and mobility, particularly in prestrained electronic devices and flexible electronics that undergo large changes in strain during operation. Raman spectroscopy, high-resolution transmission electron microscopy, and electron diffraction are utilized to identify strain-energy release mechanisms of bent diamond-cubic silicon (Si) and zinc-blende GaAs nanowires, which were elastically strained to >6% at room temperature and then annealed at an elevated temperature to activate relaxation mechanisms. High-temperature annealing of bent Si-nanowires leads to the nucleation, glide, and climb of dislocations, which align themselves to form grain boundaries, thereby reducing the strain energy. Herein, Si nanowires are reported to undergo polygonization, which is the formation of polygonal-shaped grains separated by grain boundaries consisting of aligned edge dislocations. Furthermore, strain is shown to drive dopant diffusion. In contrast to the behavior of Si, GaAs nanowires release strain energy by forming nanocracks in regions of tensile strain due to the weakening of As-bonds. These insights into the relaxation behavior of highly strained crystals can inform the design of nanoelectronic devices and provide guidance on mitigating degradation.

6.
Cell Death Dis ; 9(6): 667, 2018 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-29867111

RESUMO

The liver is an immunological organ with a distinct immune cell profile. Although the composition and function of liver immune cells have been widely investigated, the mechanisms regulating the development and homeostasis of the specialized immune system, especially in humans, remain largely unknown. Herein, we address this question in humanized mice (hu-mice) that were constructed by transplantation of human fetal thymus and CD34+ hematopoietic stem/progenitor cells in immunodeficient mice with or without autologous human hepatocyte engraftment. Although the levels of human immune cell reconstitution in peripheral blood and spleen were comparable between hu-mice with and without human hepatocyte engraftment, the former group showed that human immune cell reconstitution in the liver was significantly improved. Notably, human immune cells, including Kupffer cells, dendritic cells and natural killer cells, were shown to be closely colocalized with human hepatocytes in the liver. Human hepatocytes engrafted in the mouse liver were found to produce IL-3, IL-15, GM-CSF, M-CSF, MCP-1, CXCL-1 and CXCL-10, which are known to be important for immune cell development, differentiation, tissue migration and retention, and have no or poor cross-reaction between humans and mice. Furthermore, human hepatocytes were able to support human immune cell survival and expansion in an in vitro co-culture assay. This study demonstrates an essential role for hepatocytes in the development and maintenance of the liver immune cell profile. The hu-mouse model with human autologous immune cell and hepatocyte reconstitution has potential for use in studies of the pathogenesis of liver immune disorders such as hepatotropic virus infections.


Assuntos
Hepatócitos/metabolismo , Sistema Imunitário/metabolismo , Fígado/imunologia , Animais , Anticorpos/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Quimiocinas/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hematopoese/efeitos dos fármacos , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/transplante , Humanos , Fígado/citologia , Linfopoese/efeitos dos fármacos , Camundongos SCID , Timo/embriologia , Timo/transplante
7.
Oncotarget ; 8(1): 51-63, 2017 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-27980216

RESUMO

During human cytomegalovirus (CMV) infection after umbilical cord blood or HLA-matched hematopoietic stem cell transplantation (HSCT), a population of NKG2C-expressing natural killer (NK) cells expand and persist. The expanded NK cells express high levels of inhibitory killer immunoglobulin-like receptors (KIR) specific for self-HLA and potently produce IFNγ. However, it remains unknown whether similar events would occur after haploidentical HSCT (haplo-HSCT). Here, we demonstrated that IFNγ-producing NK cells were expanded in haplo-HSCT patients with CMV reactivation. We then identified these expanded cells as a subset of CD56dim NK cells that expressed higher levels of both NKG2C and KIR, but lower level of NKG2A. Functionally, the subset of NK cells expressing NKG2C and self-KIR in patients with CMV reactivation accounted for IFNγ production in response to K562 cells. However, these phenomena were not observed in patients without CMV reactivation. We therefore characterized a subset of NK cells with the CD56dim, NKG2C+, and self-KIR+ phenotype that expanded and were responsible for IFNγ production during CMV infection after haplo-HSCT. Together, these findings support a notion that CMV reactivation induces expansion of more mature NK cells with memory-like features, which contributes to long-term control of both CMV infection and leukemia relapse after haplo-HSCT.


Assuntos
Infecções por Citomegalovirus/etiologia , Infecções por Citomegalovirus/metabolismo , Citomegalovirus/imunologia , Transplante de Células-Tronco Hematopoéticas , Interferon gama/biossíntese , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Adolescente , Adulto , Biomarcadores , Criança , Pré-Escolar , Feminino , Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Células K562 , Masculino , Pessoa de Meia-Idade , Subfamília C de Receptores Semelhantes a Lectina de Células NK/genética , Subfamília C de Receptores Semelhantes a Lectina de Células NK/metabolismo , Fenótipo , Canais de Potássio Corretores do Fluxo de Internalização/genética , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Fatores de Tempo , Transplante Homólogo , Ativação Viral/imunologia , Adulto Jovem
8.
Huan Jing Ke Xue ; 24(1): 98-102, 2003 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-12708297

RESUMO

Compared with polyaluminium chloride (PAC), the application efficiency of polyferric chloride (PFC) were investigated by pilot micro-flocculation deep bed filtration. The results show that, under the condition of lower dosage (Fe:Al = 3:5), the headloss cycle of PFC was 63 h, and its output in a cycle was 1504 m3/m2, but PAC headloss cycle was 53 h with its output 1266 m3/m2. It is concluded that PFC was benefit to prolong operation cycle and improve output. The research on particle removal mechanism shows that PFC could enhance the floc growth, and the PFC flocs could be effectively entrapped and dehydrated. Therefore PFC is more suitable for the micro-flocculation deep bed filtration process than PAC.


Assuntos
Compostos Férricos/química , Floculação , Polímeros/química , Purificação da Água/métodos , Cloreto de Alumínio , Compostos de Alumínio , Cloretos , Filtração
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