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1.
J Am Chem Soc ; 146(22): 15428-15437, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38795044

RESUMO

Chemical recycling to monomers (CRM) offers a promising closed-loop approach to transition from current linear plastic economy toward a more sustainable circular paradigm. Typically, this approach has focused on modulating the ceiling temperature (Tc) of monomers. Despite considerable advancements, polymers with low Tc often face challenges such as inadequate thermal stability, exemplified by poly(γ-butyrolactone) (PGBL) with a decomposition temperature of ∼200 °C. In contrast, floor temperature (Tf)-regulated polymers, particularly those synthesized via the ring-opening polymerization (ROP) of macrolactones, inherently exhibit enhanced thermodynamic stability as the temperature increases. However, the development of those Tf regulated chemically recyclable polymers remains relatively underexplored. In this context, by judicious design and efficient synthesis of a biobased macrocyclic diester monomer (HOD), we developed a type of Tf -regulated closed-loop chemically recyclable poly(ketal-ester) (PHOD). First, the entropy-driven ROP of HOD generated high-molar mass PHOD with exceptional thermal stability with a Td,5% reaching up to 353 °C. Notably, it maintains a high Td,5% of 345 °C even without removing the polymerization catalyst. This contrasts markedly with PGBL, which spontaneously depolymerizes back to the monomer above its Tc in the presence of catalyst. Second, PHOD displays outstanding closed-loop chemical recyclability at room temperature within just 1 min with tBuOK. Finally, copolymerization of pentadecanolide (PDL) with HOD generated high-performance copolymers (PHOD-co-PPDL) with tunable mechanical properties and chemical recyclability of both components.

2.
Angew Chem Int Ed Engl ; 63(22): e202404179, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38488293

RESUMO

Chemical recycling of polymers to monomers presents a promising solution to the escalating crisis associated with plastic waste. Despite considerable progress made in this field, the primary efforts have been focused on redesigning new monomers to produce readily recyclable polymers. In contrast, limited research into the potential of seemingly "non-polymerizable" monomers has been conducted. Herein, we propose a paradigm that leverages a "chaperone"-assisted strategy to establish closed-loop circularity for a "non-polymerizable" α, ß-conjugated lactone, 5,6-dihydro-2H-pyran-2-one (DPO). The resulting PDPO, a structural analogue of poly(δ-valerolactone) (PVL), exhibits enhanced thermal properties with a melting point (Tm) of 114 °C and a decomposition temperature (Td,5%) of 305 °C. Notably, owing to the structural similarity between DPO and δ-VL, the copolymerization generates semi-crystalline P(DPO-co-VL)s irrespective of the DPO incorporation ratio. Intriguingly, the inherent C=C bonds in P(DPO-co-VL)s enable their convenient post-functionalization via Michael-addition reaction. Lastly, PDPO was demonstrated to be chemically recyclable via ring-closing metathesis (RCM), representing a significant step towards the pursuit of enabling the closed-loop circularity of "non-polymerizable" lactones without altering the ultimate polymer structure.

3.
J Mater Chem B ; 12(6): 1569-1578, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38252543

RESUMO

Antimicrobial peptide-mimicking antibacterial polymers represent a practical strategy to conquer the ever-growing threat of antimicrobial resistance. Herein, we report the syntheses and antibacterial performance of degradable amphiphilic cationic polyesters containing pendent quaternary ammonium motifs and hydrophobic alkyl or fluoroalkyl groups. These polyesters were conveniently prepared from poly(3-methylene-1,5-dioxepan-2-one) via highly efficient one-pot successive thiol-Michael addition reactions. The antibacterial activity of these polyesters against S. aureus and E. coli and their hemolytic activity toward red blood cells were evaluated; some of them showed moderate antibacterial activity and selectivity against Gram-positive S. aureus. The membrane disruption mechanism of these cationic polyesters was briefly explored by monitoring the bacteria killing kinetics and SEM observations. Moreover, the effects of cationic/hydrophobic ratio and the incorporation of fluoroalkyl groups on the antibacterial activity and selectivity of the polyesters were demonstrated.


Assuntos
Escherichia coli , Poliésteres , Poliésteres/química , Staphylococcus aureus , Polímeros/química , Antibacterianos/farmacologia
4.
Sensors (Basel) ; 23(20)2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37896482

RESUMO

To better improve the ride comfort and handling stability of vehicles, a new two-stage ISD semi-active suspension structure is designed, which consists of the three elements, including an adjustable damper, spring, and inerter. Meanwhile, a new semi-active ISD suspension control strategy is proposed based on this structure. Firstly, the fuzzy neural network's initial parameters are optimized using the grey wolf optimization algorithm. Then, the fuzzy neural network with the optimal parameters is adjusted to the PID parameters. Finally, a 1/4 2-degree-of-freedom ISD semi-active suspension model is constructed in Matlab/Simulink, and the dynamics simulation is carried out for the three schemes using PID control, fuzzy neural network PID control, and improved fuzzy neural network PID control, respectively. The results show that compared with adopting PID control and fuzzy neural network PID control strategy, the vehicle body acceleration and tire dynamic loads are significantly reduced after using the grey wolf optimized fuzzy neural network PID control strategy, which shows that the control strategy proposed in this paper can significantly improve the vehicle smoothness and the stability of the handling.

5.
Artigo em Inglês | MEDLINE | ID: mdl-37855295

RESUMO

Cyclic adenosine monophosphates (cAMP) and cyclic guanosine monophosphate (cGMP) are two essential second messengers, which are hydrolyzed by phosphodiesterase's (PDEs), such as PDE-2. Pharmacological inhibition of PDE-2 (PDE2A) in the central nervous system improves cAMP and cGMP signaling, which controls downstream proteins related to neuropsychiatric, neurodegenerative, and neurodevelopmental disorders. Considering that there are no specific treatments for these disorders, PDE-2 inhibitors' development has gained more attention in the recent decade. There is high demand for developing new-generation drugs targeting PDE2 for treating diseases in the central nervous and peripheral systems. This review summarizes the relationship between PDE-2 with neuropsychiatric, neurodegenerative, and neurodevelopmental disorders as well as its possible treatment, mainly involving inhibitors of PDE2.

6.
Sci Rep ; 13(1): 15656, 2023 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-37730828

RESUMO

A novel composite hydrogel (AM/CMC/B) synthesized from peanut shell biochar effectively adsorbs heavy metal Cd in water and reduces its toxicity to tobacco seedlings. The hydrogel, prepared via hydrothermal polymerization using acrylamide (AM), carboxymethyl cellulose (CMC), and peanut shell biochar (B), exhibited a maximum adsorption capacity of 164.83 mg g-1 for Cd2+ and followed a pseudo-second-order kinetic model. In pot experiments, the application of exogenous AM/CMC/B mitigated the inhibitory effects of Cd-contaminated soil on tobacco seedling growth. Addition of 10 mg kg-1 Cd resulted in improved phenotype, root system development, enhanced photosynthetic capacity, stomatal conductance (Gs), stomatal number, and increased antioxidant activity while reducing MDA content and leaf cell death. These findings highlight the potential of AM/CMC/B as an environmentally friendly adsorbent for Cd removal from water and for reducing Cd stress toxicity in tobacco and other plants.


Assuntos
Cádmio , Metais Pesados , Cádmio/toxicidade , Plântula , Nicotiana , Hidrogéis , Água , Metais Pesados/toxicidade , Acrilamida , Arachis , Carboximetilcelulose Sódica
8.
Int J Neuropsychopharmacol ; 26(6): 415-425, 2023 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-37208298

RESUMO

BACKGROUND: Phosphodiesterase 2A (PDE2A) represents a novel target for new therapies addressing psychiatric disorders. To date, the development of PDE2A inhibitors suitable for human clinical evaluation has been hampered by the poor brain accessibility and metabolic stability of the available compounds. METHODS: Corticosterone (CORT)-induced neuronal cell lesion and restraint stress mouse model were used to measure the neuroprotective effect in cells and antidepressant-like behavior in mice. RESULTS: The cell-based assay showed that both Hcyb1 and PF were potent in protecting cells against stress hormone CORT insults by stimulating cAMP and cGMP signaling in hippocampal cells (HT-22). Administration of both compounds before treatment of CORT to cells increased cAMP/cGMP, VASP phosphorylation at Ser239 and Ser157, cAMP response element binding protein phosphorylation at Ser133, and brain derived neurotrophic factor BDNF expression. Further in vivo study showed that both Hcyb1 and PF displayed -antidepressant- and anxiolytic-like effects against restraint stress as indicated by reduced immobility time in the forced swimming and tail suspension tasks as well as increased open arm entries and time spent in open arms and holes visit in elevated plus maze and hole-board tests, respectively. The biochemical study confirmed that these antidepressant- and anxiolytic-like effects of Hcyb1 and PF were related to cAMP and cGMP signaling in the hippocampus. CONCLUSIONS: The results extend the previous studies and validate that PDE2A is a tractable target for drug development in the treatment of emotional disorders such as depression and anxiety.


Assuntos
Ansiolíticos , Inibidores de Fosfodiesterase , Camundongos , Humanos , Animais , Inibidores de Fosfodiesterase/farmacologia , Depressão/psicologia , Ansiolíticos/farmacologia , Antidepressivos/uso terapêutico , Ansiedade/tratamento farmacológico , Ansiedade/induzido quimicamente , Hipocampo , Diester Fosfórico Hidrolases/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Comportamento Animal , Modelos Animais de Doenças
9.
Phys Chem Chem Phys ; 25(8): 6142-6152, 2023 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-36752130

RESUMO

The olivine phosphate family has been widely utilized as cathode materials for high-performance lithium-ion batteries. However, limited energy density and poor rate performance caused by low electronic and ionic conductivities are the main obstacles that need to be overcome for their widespread application. In this work, atomic simulations have been performed to study the effects of lattice strains on the Li+ ion migration energy barrier in olivine phosphates LiMPO4 (M = Mn, Fe, Co) and (LiFePO4)n(LiMnPO4)m superlattices (SLs). The (LiFePO4)n(LiMnPO4)m superlattices include three ratios of LFP/LMP, namely SL3 + 1, SL1 + 1 and SL1 + 3, each of which is along three typical (100), (010) and (001) orientations. We mainly discuss two migration paths of Li+ ions: the low-energy path A channel parallel to the b-axis and the medium-energy path B channel parallel to the c-axis. It is found that the biaxial tensile strain perpendicular to the migration path is most beneficial to reduce the migration energy barrier of Li+ ions, and the strain on the b-axis has a dominant effect on the energy barrier of Li+ ion migration. For path A, SL3 + 1 alternating periodically along the (010) orientation can obtain the lowest Li ion migration energy barrier. For path B, SL1 + 3 is the most favorable for Li+ ion migration, and there is no significant difference among the three orientations. Our work provides reference values for cathode materials and battery design.

10.
Chem Asian J ; 18(7): e202201238, 2023 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-36756897

RESUMO

A fully renewable bio-based bicyclic lactone containing a five-membered cyclic ketal moiety, 7-methyl-3,8,10-trioxabicyclo[5.2.1]decan-4-one (TOD), was synthesized through a two-step acid-catalyzed process from glycerol and levulinic acid. The ring-opening polymerization (ROP) of TOD at 30°C with benzyl alcohol (BnOH) as the initiator and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst can afford high molar mass PTOD with a cis-2.4-disubstitued 2-methyl 1,3-dioxolane moiety in its repeating unit. PTOD is an amorphous polymer with a glass transition temperature (Tg ) of 13°C. It can be hydrolyzed into structurally defined small molecules under acidic or basic conditions by the selective cleavage of either the cyclic ketal or the ester linkage respectively. The TBD-catalyzed copolymerization of L-lactide (L-LA) and TOD at -20°C was investigated. It was confirmed that L-LA polymerized quickly with racemization to form PLA, followed by a slow incorporation of TOD into the formed PLA chains via transesterification. By varying the feed ratios of L-LA to TOD, a series of random copolymers (PLA-co-PTOD) with different TOD incorporation ratios and tunable Tg s were obtained. Under acidic conditions, PLA-co-PTOD degrades much faster than PLA via the selective cleavage of the cyclic ketal linkages. This work provides insights for the development of more sustainable and acid-accelerated degradable alternatives to aliphatic polyesters.

11.
Ann Transl Med ; 11(2): 123, 2023 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-36819540

RESUMO

Background: To explore the key genes, biological functions, and pathways of empagliflozin in the treatment of type 2 diabetes mellitus (T2DM) through network pharmacology. Methods: The TCMSP (a traditional Chinese medicine system pharmacology database and analysis platform) was used to screen empagliflozin's active components and targets. The target genes of T2DM were screened according to the GeneCards and OMIM databases, and a Venn diagram was constructed to obtain the target for T2DM treatment. Cytoscape 3.7.2 software was adopted to construct the drug-component-target-disease network. Functional annotation of Gene Ontology (GO) and enrichment analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were performed using R software. Results: Target genes with a probability >0 were selected, among which Compound 012, Compound 060, Compound 093, Compound 111, and Compound 119 Swiss Target Prediction suggested that no similar active substances or predictable target genes were found. A "compound-target gene-disease" network was constructed, in which SLC5A2, SLC5A1, SLC5A4, SLC5A11, ADK, and ADORA2A were the core genes of T2DM. The key factors of the GO summary map included chemical reaction, membrane organelle, protein binding, and so on. The KEGG pathway summary map included the AMPK pathway, insulin resistance, the MAPK pathway, longevity-related pathway regulation, and so on. The top 10 pathways were endocrine resistance, the NF-κB signaling pathway, the HIF-1 signaling pathway, apoptosis, cell senescence, the Ras signaling pathway, the MAPK signaling pathway, the FoxO signaling pathway, the P13K-Akt signaling pathway, and the p53 signaling pathway. The binding of active compounds to key proteins was verified based on the Swiss Dock database, and the molecular docking of 193 bioactive compounds was finally verified. Among them, SLC5A2, SLC5A1, LDHA, KLK1, KLF5, and GSTP1 had better binding to the protein molecules. Conclusions: Empagliflozin may regulate the targets of SLC5A2, SLC5A1, LDHA, KLK1, KLF5, and GSTP1. There are numerous ways of treating T2DM with empagliflozin, including by regulating apoptosis, cell aging, as well as the NF-κB, HIF-1HIF-1, Ras, MAPK, FoxO, P13K-Akt, and p53 pathways.

12.
Macromol Rapid Commun ; 44(6): e2200888, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36583944

RESUMO

Polymer dielectrics with high energy density are of urgent demand in electric and electronic devices, but the tradeoff between dielectric constant and breakdown strength is still unsolved. Herein, the synthesis and molar mass control of three alternating [1.1.1]propellane-(meth)acrylate copolymers, denoted as P-MA, P-MMA, and P-EA, respectively, are reported. These copolymers exhibit high thermal stability and are semi-crystalline with varied glass transition temperatures and melting temperatures. The rigid bicyclo[1.1.1]pentane units in the polymer backbone promote the orientational polarization of the polar ester groups, thus enhancing the dielectric constants of these polymers, which are 4.50 for P-EA, 4.55 for P-MA, and 5.11 for P-MMA at 10 Hz and room temperature, respectively. Moreover, the high breakdown strength is ensured by the non-conjugated nature of bicyclo[1.1.1]pentane unit. As a result, these copolymers show extraordinary energy storage performance; P-MA exhibits a discharge energy density of 9.73 J cm-3 at 750 MV m-1 and ambient temperature. This work provides a new type of promising candidates as polymer dielectrics for film capacitors, and offers an efficient strategy to improve the dielectric and energy storage properties by introducing rigid non-conjugated bicyclo[1.1.1]pentane unit into the polymer backbone.


Assuntos
Metanfetamina , Pentanos , Acrilatos , Polímeros
13.
Biomacromolecules ; 23(12): 5213-5224, 2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36382861

RESUMO

Poly(α-methylene ester)s are an attractive type of functional aliphatic polyesters that represent a platform for the fabrication of various biodegradable and biomedical polymers. Herein, we report the controlled ring-opening polymerization (ROP) of a seven-membered α-methylene lactone (3-methylene-1,5-dioxepan-2-one, MDXO) that was synthesized based on the Baylis-Hillman reaction. The chemoselective ROP of MDXO was catalyzed by diphenyl phosphate (DPP) at 60 °C or stannous octoate (Sn(Oct)2) at 130 °C, generating α-methylene-containing polyester (PMDXO) with a linear structure and easily tunable molar mass. The ring-opening copolymerization of MDXO with ε-caprolactone or 1,5-dioxepan-2-one was also performed under the catalysis of DPP or Sn(Oct)2 to afford copolymers with different compositions and sequence structures that are influenced by the kinds of monomers and catalysts. PMDXO is a slowly crystallizable polymer with a glass transition temperature of ca. -33 °C, and its melting temperature and enthalpy are significantly influenced by the thermal history. The thermal properties of the copolymers are dependent on their composition and sequence structure. Finally, the post-modification of PMDXO based on the thiol-Michael addition reaction was briefly explored using triethylamine as a catalyst. Given the optimized condition, PMDXO could be dually modified to afford biodegradable polyesters with different functionalities.


Assuntos
Materiais Biocompatíveis , Ésteres , Materiais Biocompatíveis/química , Poliésteres/química , Polímeros/química
14.
Neuropharmacology ; 213: 109128, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35588859

RESUMO

Our previous study suggested that inhibition of Phosphodiesterase 2 ameliorates memory loss upon exposure to oxidative stress. While whether memory enhancing effects of PDE2 inhibition on Alzheimer's disease mouse model are involved in antioxidant defense and neuronal remodeling, are largely unexplored. The present study addressed whether and how PDE2 inhibitor Bay 60-7550 rescued Aß oligomers (Aßo)-induced neuronal damage and memory impairment. The results suggested that exposure of primary cortical neurons to Aßo induced neuronal cells damage and increased PDE2 expression, which were paralleled to an increase in the oxidative parameter malondialdehyde (MDA) level and cellular apoptosis. However, this Aßo-induced oxidative damage was blocked by pre-treatment with protein kinase A or G (PKA or PKG) inhibitor, suggesting the involvement of cAMP/cGMP signaling. Moreover, microinjection of Aßo into the prefrontal cortex of mice increased the MDA level; while Bay 60-7550 reversed this effect and increased antioxidant and anti-apoptotic factors, i.e. increased trolox-equivalent-antioxidant capacity and Bcl-2/Bax ratio. Bay 60-7550 also rescued Aßo-induced synaptic atrophy and memory deficits, as evidenced by the increased synaptic proteins' levels and spine density in the prefrontal cortex, and improved cognitive behaviors by decreased working memory errors in the eight-arm maze and increased discrimination index in the novel object recognition test. These findings suggest that inhibition of PDE2 contributes to antioxidant defense and neuronal remodeling by regulation of cAMP/cGMP signaling, which provide a theoretical basis for the future use of PDE2 inhibitors as the anti-AD drugs.


Assuntos
Doença de Alzheimer , Inibidores de Fosfodiesterase , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Antioxidantes/farmacologia , GMP Cíclico/farmacologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2 , Hipocampo , Transtornos da Memória/tratamento farmacológico , Camundongos , Camundongos Endogâmicos ICR , Neurônios , Fragmentos de Peptídeos , Inibidores de Fosfodiesterase/farmacologia , Inibidores de Fosfodiesterase/uso terapêutico
15.
Sensors (Basel) ; 22(9)2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35591227

RESUMO

To ensure the safe operation of highway traffic lines, given the imperfect feature extraction of existing road pit defect detection models and the practicability of detection equipment, this paper proposes a lightweight target detection algorithm with enhanced feature extraction based on the YOLO (You Only Look Once) algorithm. The BIFPN (Bidirectional Feature Pyramid Network) network structure is used for multi-scale feature fusion to enhance the feature extraction ability, and Varifocal Loss is used to optimize the sample imbalance problem, which improves the accuracy of road defect target detection. In the evaluation test of the model in the constructed PCD1 (Pavement Check Dataset) dataset, the mAP@.5 (mean Average Precision when IoU = 0.5) of the BV-YOLOv5S (BiFPN Varifocal Loss-YOLOv5S) model increased by 4.1%, 3%, and 0.9%, respectively, compared with the YOLOv3-tiny, YOLOv5S, and B-YOLOv5S (BiFPN-YOLOv5S; BV-YOLOv5S does not use the Improved Focal Loss function) models. Through the analysis and comparison of experimental results, it is proved that the proposed BV-YOLOv5S network model performs better and is more reliable in the detection of pavement defects and can meet the needs of road safety detection projects with high real-time and flexibility requirements.


Assuntos
Algoritmos , Redes Neurais de Computação
16.
ACS Appl Mater Interfaces ; 14(9): 11663-11671, 2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35195983

RESUMO

Broad-band near-infrared (NIR) phosphors are essential to assembling portable NIR light sources for applications in spectroscopy technology. However, developing inexpensive, efficient, and thermally stable broad-band NIR phosphors remains a significant challenge. In this work, a phosphate, KAlP2O7, with a wide band gap and suitable electronic environment for Cr3+ equivalent substitution was selected as the host material. The synthesized KAlP2O7:Cr3+ material exhibits a broad-band emission covering 650-1100 nm with a peak centered at 790 nm and a full width at half-maximum (fwhm) of 120 nm under 450 nm excitation. The internal quantum efficiency (IQE) was determined to be 78.9%, and the emission intensity at 423 K still maintains 77% of that at room temperature, implying the high efficiency and excellent thermal stability of this material. Finally, a NIR phosphor-converted light-emitting diode (pc-LED) device was fabricated by using the as-prepared material combined with a 450 nm blue LED chip, which presents a high NIR output power of 32.1 mW and excellent photoelectric conversion efficiency of 11.4% under a drive current of 100 mA. Thus, this work not only provides an inexpensive broad-band NIR material with high performance for applications in NIR pc-LEDs but also highlights some strategies to explore this class of materials.

17.
Exp Mol Med ; 53(9): 1366-1378, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34548615

RESUMO

PD-L1 is abnormally regulated in many cancers and is critical for immune escape. Fully understanding the regulation of PD-L1 expression is vital for improving the clinical efficacy of relevant anticancer agents. TGF-ß plays an important role in the low reactivity of PD-1/PD-L1 antibody immunotherapy. However, it is not very clear whether and how TGF-ß affects PD-L1 expression. In the present study, we show that TGF-ß upregulates the expression of the transcriptional coactivator MRTF-A in non-small-cell lung cancer cells, which subsequently interacts with NF-κB/p65 rather than SRF to facilitate the binding of NF-κB/p65 to the PDL1 promoter, thereby activating the transcription and expression of PD-L1. This leads to the immune escape of NSCLC cells. This process is dependent on the activation of the TGF-ß signaling pathway. In vivo, inhibition of MRTF-A effectively suppresses the growth of lung tumor syngrafts with enrichment of NK and T cells in tumor tissue. Our study defines a new signaling pathway that regulates the transcription and expression of PD-L1 upon TGF-ß treatment, which may have a significant impact on research into the application of immunotherapy in treating lung cancer.


Assuntos
Antígeno B7-H1/genética , Carcinoma Pulmonar de Células não Pequenas/etiologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Evasão da Resposta Imune/genética , Neoplasias Pulmonares/etiologia , Neoplasias Pulmonares/metabolismo , Transativadores/metabolismo , Fator de Transcrição RelA/metabolismo , Animais , Biomarcadores , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Suscetibilidade a Doenças , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Xenoenxertos , Humanos , Neoplasias Pulmonares/patologia , Camundongos , Modelos Biológicos , Complexo de Endopeptidases do Proteassoma/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Ubiquitina/metabolismo
18.
ACS Appl Mater Interfaces ; 13(27): 31835-31842, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34185499

RESUMO

Broadband near-infrared (NIR) emitting materials are in great demand as next-generation smart NIR light sources. In this work, a Cr3+-substituted phosphor capable of efficiently converting visible to NIR light is developed through the solid solution, Ga2-xInxO3:Cr3+ (0 ≤ x ≤ 0.5). The compounds were prepared using high-temperature solid-state synthesis, and the crystal and electronic structure, morphology, site preference, and photoluminescence properties are studied. The photoluminescence results demonstrate a high quantum yield (88%) and impressive absorption efficiency (50%) when x = 0.4. The NIR emission is tunable across a wide range (713-820 nm) depending on the value of x. Moreover, fabricating a prototype of a phosphor-converted NIR light-emitting diode (LED) device using 450 nm LED and the [(Ga1.57Cr0.03)In0.4]O3 phosphor showed an output power that reached 40.4 mW with a photoelectric conversion efficiency of 25% driven by a current of 60 mA, while the resulting device was able to identify damaged produce that was undetectable using visible light. These results demonstrate the outstanding potential of this phosphor for NIR LED imaging applications.

19.
Macromol Rapid Commun ; 42(18): e2100169, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34028933

RESUMO

Self-immolative polymers are a special kind of degradable polymers that depolymerize into small molecules through a cascade of reactions upon stimuli-triggered cleavage of the polymer chain ends. This work reports the design and synthesis of a fluoride-triggered self-immolative polyester. A 2,4-disubstitued 4-hydroxy butyrate is first confirmed to quickly cyclize in solution to form a γ-butyrolactone derivative. Then, the Passerini three component reaction (P-3CR) of an AB dimer (A: aldehyde, B: carboxylic acid) with tert-butyl isocyanide or oligo(ethylene glycol) isocyanide affords two poly(2,4-disubstitued 4-hydroxybutyrate) derivatives (P2 and P3). Two silyl ether end-capped polymers (P4 and P5) are abtained from P2 and P3, and their degradation in solution is examined by NMR spectrum and size exclusion chromatography. Polymers P4 and P5 are stable in the absence of tetrabutylammonium fluoride (TBAF), while in the presence of TBAF, the molar masses of P4 and P5 gradually decrease with time together with the increase of the amount of formed 2,4-disubstitued γ-butyrolactone. The depolymerization mechanism is proposed. The first step is the fast removal of the silyl ether by fluoride. Then, the released hydroxyl group initiates the quick head-to-tail depolymerization of the polyester via intramolecular cyclization.


Assuntos
Fluoretos , Polímeros , Hidroxibutiratos , Poliésteres
20.
Toxicol Rep ; 8: 896-907, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33996503

RESUMO

Animal models are essential for evaluating the toxicity of chemical warfare nerve agents (CWNAs) to extrapolate to human risk and are necessary to evaluate the efficacy of medical countermeasures. The Göttingen minipig is increasingly used for toxicological studies because it has anatomical and physiological characteristics that are similar to those of humans. Our objective was to determine whether the minipig would be a useful large animal model to evaluate the toxic effects of soman (GD). We determined the intramuscular (IM) median lethal dose (LD50) of GD in adult male Göttingen minipigs using an up-and-down dosing method. In addition to lethality estimates, we characterized the observable signs of toxicity, blood and tissue cholinesterase (ChE) activity and brain pathology following GD exposure. The 24 h LD50 of GD was estimated to be 4.7 µg/kg, with 95 % confidence limits of 3.6 and 6.3 µg/kg. As anticipated, GD inhibited ChE activity in blood and several tissues. Neurohistopathological analysis showed neurodegeneration and neuroinflammation in survivors exposed to 4.7 µg/kg of GD, including in the primary visual cortex and various thalamic nuclei. These findings suggest that the minipig will be a useful large animal model for assessing drugs to mitigate neuropathological effects of exposure to CWNAs.

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