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1.
Plant J ; 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-32808386

RESUMO

Brassica napus is currently cultivated as an important ornamental crop in China. Flower color has attracted much attention in rapeseed genetics and breeding. Here, we characterize an orange-flowered mutant of B. napus that exhibits an altered carotenoid profile in its petals. As revealed by map-based cloning, the change in color from yellow to orange is attributed to the loss of BnaC09.ZEP (zeaxanthin epoxidase) and a 1,695-bp deletion in BnaA09.ZEP. HPLC analysis, genetic complementation and the CRISPR/Cas9 experiments demonstrated that BnaA09.ZEP and BnaC09.ZEP have similar functions, and the abolishment of both genes led to a substantial increase in lutein content and a sharp decline in violaxanthin content in petals but not leaves. BnaA09.ZEP and BnaC09.ZEP are predominantly expressed in floral tissues, whereas their homologs, BnaA07.ZEP and BnaC07.ZEP mainly function in leaves, indicating redundancy and tissue-specific diversification of BnaZEPs function. Transcriptome analysis in petals revealed the differences in expression of carotenoid and flavonoid biosynthesis-related genes between the mutant and its complementary lines. Flavonoid profiles in the petals of complementary lines were greatly altered compared to the mutant, indicating a potential crosstalk between the regulatory networks underlying the carotenoid and flavonoid pathways. Additionally, our results indicated that there is functional compensation by BnaA07.ZEP and BnaC07.ZEP in the absence of BnaA09.ZEP and BnaC09.ZEP. Cloning and characterization of BnaZEPs provide insights into the molecular mechanisms underlying flower pigmentation in B. napus and would facilitate breeding of B. napus varieties with higher ornamental value.

2.
Small ; : e2002856, 2020 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-32797720

RESUMO

A highly electrically conductive film-type current collector is an essential part of batteries. Apart from the metal-based current collectors, lightweight and highly conductive carbon materials such as reduced graphene oxide (RGO) and carbon nanotubes (CNTs) show great potential as current collectors. However, traditional RGO manufacturing usually requires a long time and high energy, which decreases the product yielding rate and manufacturing efficiency. Moreover, the performance of the manufactured RGO needs to be further improved. In this work, CNT and GO are evenly mixed into GO-CNT, which can be directly reduced into RGO-CNT by Joule heating at 2936 K within less than 1 min. The fabricated RGO-CNT achieves a high electrical conductivity of 2750 S cm-1 , and realizes a 106 -fold increase. The assembled flexible aqueous Al-ion battery with RGO-CNT as the current collector exhibits impressive electrochemical performance in terms of superior cycling stability and exceptional rate capability, and excellent mechanical ability regarding the tolerance to mechanical damage such as bending, folding, piercing, and cutting without detrimental consequences.

3.
J Neuroinflammation ; 17(1): 191, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32546267

RESUMO

BACKGROUND: The regulation of vascular smooth muscle cell (VSMC) phenotype plays an important role in intracranial aneurysm (IA) formation and progression. However, the underlying mechanism remains unclear. Metformin is a 5' AMP-activated protein kinase (AMPK) agonist that has a protective effect on vasculature. The present study investigated whether metformin modulates VSMC phenotype switching via the AMPK/acetyl-CoA carboxylase (ACC) pathway during IA pathogenesis. METHODS: Adult male Sprague-Dawley rats (n = 80) were used to establish an elastase-induced IA model. The effects of metformin on AMPK activation and VSMC phenotype modulation were examined. We also established a platelet-derived growth factor (PDGF)-BB-induced VSMC model and analyzed changes in phenotype including proliferation, migration, and apoptosis as well as AMPK/ACC axis activation under different doses of metformin, AMPK antagonist, ACC antagonist, and their combinations. RESULTS: Metformin decreased the incidence and rupture rate of IA in the rat model and induced a switch in VSMC phenotype from contractile to synthetic through activation of the AMPK/ACC pathway, as evidenced by upregulation of VSMC-specific genes and decreased levels of pro-inflammatory cytokines. AMPK/ACC axis activation inhibited the proliferation, migration, and apoptosis of VSMCs, in which phenotypic switching was induced by PDGF-BB. CONCLUSIONS: Metformin protects against IA formation and rupture by inhibiting VSMC phenotype switching and proliferation, migration, and apoptosis. Thus, metformin has therapeutic potential for the prevention of IA.

4.
Biomed Pharmacother ; 128: 110246, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32447210

RESUMO

BACKGROUND: Dysregulated microRNAs (miRNAs/miRs) directly modulate the biological functions of gastric cancer (GC) cells and contribute to the initiation and progression of GC. MiR-17-5p and runt-related transcription factor 3 (RUNX3) have been reported to be related to GC progression; however, the specific interaction between miR-17-5p and RUNX3 in GC require further investigation. METHODS: Western blotting, real-time PCR and immunohistochemistry were used to study the expression level of miR-17-5p and RUNX3 in gastric cancer tissues and plasma. The biological function of miR-17-5p was examined by measuring cell proliferation, apoptosis and cell invasion in vitro; the target gene of miR17-5p was identified by luciferase reporter assays, RNA Binding protein immunoprecipitation (RIP) and western blotting. In vivo animal study was conducted to confirm the role of miR-17-5p during tumorigensis of gastric cancer. RESULTS: This study showed that miR17-5p was upregulated in the plasma and tissues of patients with GC, while RUNX3 was downregulated in GC tissues. Functional experiments indicated that miR-17-5p mimics promoted the proliferation and invasion of GC via suppressing apoptosis in vitro. Furthermore, bioinformatics prediction, luciferase reporter assays, reverse transcription quantitative polymerase chain reaction assays, RIP and western blotting analysis demonstrated that RUNX3 was a direct target gene of miR-17-5p in GC. In addition, overexpression of RUNX3 suppressed the proliferation and invasiveness of GC cells. In vivo data indicated miR-17-5p agomir significantly promoted tumor growth. In contrast, miR-17-5p antagomir notably decreased tumor volume compared with control group. CONCLUSIONS: MiR-17-5p promoted the progression of GC via directly targeting RUNX3, suggesting that miR-17-5p and RUNX3 could be considered as diagnostic and therapeutic targets for patients with GC.

5.
Nanoscale ; 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32458941

RESUMO

Carbon materials are widely used in numerous fields, thus changing our lives. With the increasing consumption of carbon-based products, the disposal of consequent wastes has become a challenge due to their inert nature, which is hard to degrade, burn, or melt. Here, a recyclable strategy is proposed to deal with the explosive growth of carbon wastes. Through a fast and clean electrochemical method, carbon wastes are converted into functional building blocks of high value, such as graphene and graphene quantum dots (GQDs). For typical polyimide-pyrolyzed carbon (PPC), we establish the relationship between the chemical structure of raw materials and the characteristics of graphene products, including size and yield. The size-tunable graphene ranging from 3 nm to tens of micrometers is prepared by tuning the sp3/sp2 carbon ratio of PPC from 0.5 to 0 at adjustable temperatures (800 °C-2800 °C). Significantly, PPC with a bicontinuous structure (comprising sp2 and sp3) was efficiently cut into GQDs in 2 h with a high yield of 98%. Our protocol offers great potential for the scale-up preparations and applications of GQDs. Besides, we demonstrate that the GQDs performed well as dispersants to disperse hydrophobic carbon nanotubes (0.6 mg mL-1) in water and improved the gravimetric capacitance of graphene-based supercapacitors by 79.4% with 3% GQDs added as nano-fillers.

6.
Environ Sci Technol ; 54(11): 6751-6760, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32379430

RESUMO

Measurements by semivolatile thermal desorption aerosol gas chromatography (SV-TAG) were used to investigate how semivolatile organic compounds (SVOCs) partition among indoor reservoirs in (1) a manufactured test house under controlled conditions (HOMEChem campaign) and (2) a single-family residence when vacant (H2 campaign). Data for phthalate diesters and siloxanes suggest that volatility-dependent partitioning processes modulate airborne SVOC concentrations through interactions with surface-laden condensed-phase reservoirs. Airborne concentrations of SVOCs with vapor pressures in the range of C13 to C23 alkanes were observed to be correlated with indoor air temperature. Observed temperature dependencies were quantitatively similar to theoretical predictions that assumed a surface-air boundary layer with equilibrium partitioning maintained at the air-surface interface. Airborne concentrations of SVOCs with vapor pressures corresponding to C25 to C31 alkanes correlated with airborne particle mass concentration. For SVOCs with higher vapor pressures, which are expected to be predominantly gaseous, correlations with particle mass concentration were weak or nonexistent. During primary particle emission events, enhanced gas-phase emissions from condensed-phase reservoirs partitioned to airborne particles, contributing substantially to organic particulate matter. An emission event related to oven-usage was inferred to deposit siloxanes in condensed-phase reservoirs throughout the house, leading to the possibility of reemission during subsequent periods with high particle loading.

7.
J Cell Mol Med ; 2020 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-32462812

RESUMO

Correlation between periodontitis and atherosclerosis is well established, and the inherent mechanisms responsible for this relationship remain unclear. The biological function of growth arrest-specific 6 (gas6) has been discovered in both atherosclerosis and inflammation. Inhibitory effects of gas6 on the expression of inflammatory factors in human umbilical vein endothelial cells (HUVECs) stimulated by Porphyromonas gingivalis lipopolysaccharide (P. gingivalis-LPS) were reported in our previous research. Herein, the effects of gas6 on monocytes-endothelial cells interactions in vitro and their probable mechanisms were further investigated. Gas6 protein in HUVECs was knocked down with siRNA or overexpressed with plasmids. Transwell inserts and co-culturing system were introduced to observe chemotaxis and adhering affinity between monocytes and endothelial cells in vitro. Expression of gas6 was decreased in inflammatory periodontal tissues and HUVECs challenged with P. gingivalis-LPS. The inhibitory effect of gas6 on chemotaxis and adhesion affinity between monocytes and endothelial cells was observed, and gas6 promoted Akt phosphorylation and inhibited NF-κB phosphorylation. To our best knowledge, we are first to report that gas6 inhibit monocytes-endothelial cells interactions in vitro induced by P. gingivalis-LPS via Akt/NF-κB pathway. Additionally, inflammation-mediated inhibition of gas6 expression is through LncRNA GAS6-AS2, rather than GAS6-AS1, which is also newly reported.

8.
Environ Sci Technol ; 54(10): 5980-5991, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32271021

RESUMO

Anthropogenic emissions alter secondary organic aerosol (SOA) formation chemistry from naturally emitted isoprene. We use correlations of tracers and tracer ratios to provide new perspectives on sulfate, NOx, and particle acidity influencing isoprene-derived SOA in two isoprene-rich forested environments representing clean to polluted conditions-wet and dry seasons in central Amazonia and Southeastern U.S. summer. We used a semivolatile thermal desorption aerosol gas chromatograph (SV-TAG) and filter samplers to measure SOA tracers indicative of isoprene/HO2 (2-methyltetrols, C5-alkene triols, 2-methyltetrol organosulfates) and isoprene/NOx (2-methylglyceric acid, 2-methylglyceric acid organosulfate) pathways. Summed concentrations of these tracers correlated with particulate sulfate spanning three orders of magnitude, suggesting that 1 µg m-3 reduction in sulfate corresponds with at least ∼0.5 µg m-3 reduction in isoprene-derived SOA. We also find that isoprene/NOx pathway SOA mass primarily comprises organosulfates, ∼97% in the Amazon and ∼55% in Southeastern United States. We infer under natural conditions in high isoprene emission regions that preindustrial aerosol sulfate was almost exclusively isoprene-derived organosulfates, which are traditionally thought of as representative of an anthropogenic influence. We further report the first field observations showing that particle acidity correlates positively with 2-methylglyceric acid partitioning to the gas phase and negatively with the ratio of 2-methyltetrols to C5-alkene triols.


Assuntos
Poluentes Atmosféricos , Hemiterpenos , Aerossóis/análise , Brasil , Butadienos , Pentanos , Sudeste dos Estados Unidos
9.
Exp Cell Res ; 388(1): 111839, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31935381

RESUMO

Endothelial progenitor cell (EPC) recruitment and angiogenesis play crucial roles in aneurysm neck endothelialization, but the mechanisms of EPC recruitment and angiogenesis are still unclear. Recent studies have shown that long noncoding RNAs (lncRNAs) can regulate the function and differentiation of cells in various ways. LncRNA TUG1 is involved in liver cancer and glioma-mediated angiogenesis. The aim of this study was to investigate the role of lncRNA TUG1 in regulating EPC migration and differentiation. Overexpression and knockdown of lncRNA TUG1 with lentivirus, scratch assays, Transwell assays and tube formation assays using EPCs isolated from rat bone marrow showed that lncRNA TUG1 overexpression promoted EPC migration, invasion and differentiation. Moreover, ELISAs showed that lncRNA TUG1 overexpression increased VEGF expression. Bioinformatics prediction, luciferase assays, Western blots and RIP assays indicated that lncRNA TUG1 functions as a ceRNA (competing endogenous RNA) for miR-6321 and that miR-6321 inhibits EPC migration and differentiation through its target, ATF2. As a potential therapeutic target, lncRNA TUG1 may play a vital role in the pathogenesis of aneurysms.

10.
Glia ; 68(2): 345-355, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31518022

RESUMO

Microglia play vital roles in the health and diseases of the central nervous system. Loss of microglia homeostatic state is a key feature of brain aging and neurodegeneration. However, the mechanisms underlying the maintenance of distinct microglia cellular states are largely unclear. Here, we show that NG2 glia, also known as oligodendrocyte precursor cells, are essential for maintaining the homeostatic microglia state. We developed a highly efficient and selective NG2 glia depletion method using small-molecule inhibitors of platelet-derived growth factor (PDGF) signaling in cultured brain slices. We found that loss of NG2 glia abolished the homeostatic microglia signature without affecting the disease-associated microglia profiles. Similar findings were also observed in vivo by genetically depleting NG2 glia or conditionally inhibiting NG2 glia PDGF signaling in the adult mouse brain. These data suggest that NG2 glia exert a crucial influence onto microglia cellular states that are relevant to brain aging and neurodegenerative diseases. In addition, our results provide a powerful, convenient, and selective tool for the investigation of NG2 glia function.


Assuntos
Homeostase/fisiologia , Microglia/metabolismo , Neuroglia/metabolismo , Oligodendroglia/metabolismo , Animais , Encéfalo/metabolismo , Sistema Nervoso Central/metabolismo , Camundongos Endogâmicos C57BL , Células Precursoras de Oligodendrócitos
11.
J Neuroinflammation ; 16(1): 185, 2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31585542

RESUMO

BACKGROUND: Oxidative stress and vascular smooth muscle cell (VSMC) phenotypic modulation influence intracranial aneurysm (IA) formation and progression. Oxidative stress plays an important role in phenotype switching, and nuclear factor erythroid 2-related factor 2 (Nrf-2) is one of the main antioxidant systems. Unfortunately, little is known about how Nrf-2 signaling influences VSMC phenotype switches during IA pathogenesis. METHODS: We examined the effect of Nrf-2 activation IA on formation and progression in an elastase-induced rat IA model. We also developed a hydrogen peroxide (H2O2)-induced VSMC oxidative damage model. Then, we analyzed VSMC phenotype changes in the setting of Nrf-2 activation or inhibition in vitro. The proliferation, migration ability, and apoptosis rate of VSMCs were tested. Lastly, we measured the expression levels of antioxidant enzymes and inflammatory cytokines downstream of Nrf-2. RESULTS: Nrf-2 activation suppressed IA formation and progression in vivo. We confirmed Nrf-2 nuclear translocation and a VSMC switch from the contractile to synthetic phenotype. Nrf-2 activation inhibited the proliferation, migratory ability, and apoptosis rate enhanced by H2O2. Quantitative real-time polymerase chain reaction (PCR) and western blot analysis revealed that Nrf-2 activation promoted antioxidant enzymes and VSMC-specific marker gene expressions but decreased pro-inflammatory cytokine levels. CONCLUSION: These results suggest that Nrf-2 exerts protective effects against IA development by preventing VSMCs from changing to a synthetic phenotype.


Assuntos
Aneurisma Intracraniano/metabolismo , Aneurisma Intracraniano/patologia , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Animais , Progressão da Doença , Masculino , Fenótipo , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/fisiologia
12.
Rev Sci Instrum ; 90(7): 074704, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31370469

RESUMO

A high power microwave source based on energy storage switching pulse compression technology can produce a high power microwave pulse with good repeatability and frequency stability for a long time and has a good development prospect. In order to improve the power gain, this paper studies the working characteristics of the energy extraction structure of the X-band energy storage switching pulse compression device. The theoretical analysis results show that the impedance mismatch exists in the traditional energy extraction structure after the pulse compression is transferred to the energy extraction stage and the energy extraction efficiency is not high, which results in the power gain limitation. Therefore, through theoretical calculation and simulation, an improved scheme based on output inductance diaphragm is proposed in this paper. The scheme has high power capacity and can achieve impedance matching without changing the resonant frequency of the energy storage cavity, so as to improve the power gain of the pulse compression device. The high power experimental results show that the power gain of the pulse compression device can be increased from 6.24 times to 7.22 times and the energy extraction efficiency can be increased by 17.5% by placing 17 mm slot spacing inductance diaphragm at 45 mm of the H-T arm of the waveguide, which verifies the feasibility of the improved scheme.

13.
J Neurosurg ; : 1-9, 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31398705

RESUMO

OBJECTIVE: Emerging evidence shows that frequent recurrence of intracranial aneurysms (IAs) after endovascular coiling is attributable to the lack of endothelialization across the aneurysm neck. Recently, much attention has been given to the role of microRNAs (miRs) in vascular disease, although their contributory role to IA is poorly understood. METHODS: Adult male Sprague-Dawley rats were subjected to microsurgery to create a coiled embolization aneurysm model, and were injected with miR-31a-5p agomir or a negative control agomir via the tail vein at a dose of 10 mg/kg per week for 4 weeks after IA induction. H & E staining, scanning electron microscopy, and flow cytometry were performed to evaluate the effects of miR-31a-5p agomir on endothelialization and the number of circulating endothelial progenitor cells (EPCs). The effects of miR-31a-5p on the viability and functioning of EPCs were also determined using Cell Counting Kit-8, wound-healing assay, and tube formation assays. RESULTS: The authors tested the ability of miR-31a-5p to promote EPC-induced endothelialization in a model of coiled embolization aneurysm. miR-31a-5p agomir improved endothelialization and elevated the number of circulating EPCs in the peripheral blood compared to a negative control agomir-treated group. In addition, the number of vWF- and KDR-positive cells in the aneurysm neck was increased in the miR-31a-5p agomir-treated group. Furthermore, upregulation of miR-31a-5p promoted EPC proliferation, migration, and tube formation and enhanced the expression of the proangiogenic factor vascular endothelial growth factor in vitro. Mechanistically, miR-31a-5p directly targeted the 3' untranslated region (3'UTR) of Axin1 messenger RNA and repressed its expression. Besides, miR-31a-5p exerted its effect on EPCs by regulating the Axin1-mediated Wnt/ß-catenin pathway. CONCLUSIONS: Collectively, these results indicate that miR-31a-5p is an important regulator of EPC mobilization and endothelialization and may have a positive effect on aneurysm repair.

14.
Environ Sci Technol ; 53(13): 7337-7346, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31180211

RESUMO

Phthalate esters, commonly used as plasticizers, can be found indoors in the gas phase, in airborne particulate matter, in dust, and on surfaces. The dynamic behavior of phthalates indoors is not fully understood. In this study, time-resolved measurements of airborne phthalate concentrations and associated gas-particle partitioning data were acquired in a normally occupied residence. The vapor pressure and associated gas-particle partitioning of measured phthalates influenced their airborne dynamic behavior. Concentrations of higher vapor pressure phthalates correlated well with indoor temperature, with little discernible influence from direct occupant activity. Conversely, occupant-related behaviors substantially influenced the concentrations and dynamic behavior of a lower vapor pressure compound, diethylhexyl phthalate (DEHP), mainly through production of particulate matter during cooking events. The proportion of airborne DEHP in the particle phase was experimentally observed to increase under higher particle mass concentrations and lower indoor temperatures in correspondence with theory. Experimental observations indicate that indoor surfaces of the residence are large reservoirs of phthalates. The results also indicate that two key factors influenced by human behavior-temperature and particle mass concentration-cause short-term changes in airborne phthalate concentrations.


Assuntos
Poluição do Ar em Ambientes Fechados , Dietilexilftalato , Ácidos Ftálicos , Humanos , Plastificantes
15.
Nanoscale ; 11(24): 11730-11735, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31180401

RESUMO

Thermal dissipation and thermal insulation are important for maintaining the normal operation of devices, extending the service life of instruments, ensuring efficient energy utilization, and improving temperature-related human comfort. Yet it is difficult to achieve both the functions of thermal dissipation and thermal insulation in a single material with a specific thermal conductivity under specific conditions. In this work, based on the huge difference in thermal conductivity between air and reduced graphene oxide (rGO), a pressure-induced mechanism is used to regulate the amount of air inside an rGO foam, so that a periodic reversible change of thermal conductivity can be realized, achieving the dual functions of thermal dissipation and thermal insulation to meet the requirements of different application scenarios. Further fitting calculations suggest that the thermal conductivity of rGO foam is positively and negatively associated with the applied pressure and temperature, respectively, and it can be calculated for given pressure and temperature conditions. The pressure-induced reversible regulation of thermal conductivity in rGO foam provides a new design construct for smart thermal-management devices, and a new direction of application for 2D materials.

16.
Indoor Air ; 29(4): 645-655, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31004533

RESUMO

Semivolatile organic compounds (SVOCs) emitted from building materials, consumer products, and occupant activities alter the composition of air in residences where people spend most of their time. Exposures to specific SVOCs potentially pose risks to human health. However, little is known about the chemical complexity, total burden, and dynamic behavior of SVOCs in residential environments. Furthermore, little is known about the influence of human occupancy on the emissions and fates of SVOCs in residential air. Here, we present the first-ever hourly measurements of airborne SVOCs in a residence during normal occupancy. We employ state-of-the-art semivolatile thermal-desorption aerosol gas chromatography (SV-TAG). Indoor air is shown consistently to contain much higher levels of SVOCs than outdoors, in terms of both abundance and chemical complexity. Time-series data are characterized by temperature-dependent elevated background levels for a broad suite of chemicals, underlining the importance of continuous emissions from static indoor sources. Substantial increases in SVOC concentrations were associated with episodic occupant activities, especially cooking and cleaning. The number of occupants within the residence showed little influence on the total airborne SVOC concentration. Enhanced ventilation was effective in reducing SVOCs in indoor air, but only temporarily; SVOCs recovered to previous levels within hours.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Habitação , Compostos Orgânicos Voláteis/análise , California , Materiais de Construção , Culinária , Monitoramento Ambiental/métodos , Humanos , São Francisco , Ventilação
17.
Indoor Air ; 29(4): 630-644, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31004537

RESUMO

We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single-family house in California utilizing time- and space-resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8 weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time-resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short-term enhancements (spikes) well above the indoor baseline. Compounds were categorized as "high-baseline" or "spike-dominated" based on indoor-to-outdoor concentration ratio and indoor mean-to-median ratio. Short-term spikes were associated with occupants and their activities, especially cooking. High-baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high-baseline species, quantified with 2-hour resolution, exhibited strong temperature dependence and were affected by air-change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high-baseline species.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Materiais de Construção , Decoração de Interiores e Mobiliário , Compostos Orgânicos Voláteis/análise , California , Materiais de Construção/efeitos adversos , Culinária , Monitoramento Ambiental , Feminino , Habitação , Humanos , Masculino , Pessoa de Meia-Idade , Estações do Ano
18.
ACS Nano ; 13(5): 5549-5558, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31013425

RESUMO

Shape memory polymers (SMPs) change shapes as-designed through altering the chain segment movement by external stimuli, promising wide uses in actuators, sensors, drug delivery, and deployable devices. However, the recovery speed of SMPs is still far slower than the benchmark shape memory alloys (SMAs), originating from their intrinsic poor heat transport and retarded viscoelasticity of polymer chains. In this work, monolithic nanocomposite aerogels composed of bicontinuous graphene and SMP networks are designed to promote the recovery time of SMP composites to a record value of 50 ms, comparable to the SMA case. The integration of a stretchable graphene framework as a fast energy transformation grid with ultrathin polycaprolactone nanofilms (tunable at 2.5-60 nm) enables the rapid phase transition of SMPs under electrical stimulation. The graphene-SMP nanocomposite aerogels, with a density of ∼10 mg cm-3, exhibit a fast response (175 ± 40 mm s-1), large deformation (∼100%), and a wide response bandwidth (0.1-20 Hz). The ultrafast response of SMP nanocomposite aerogels confers extensive uses in sensitive fuses, micro-oscillators, artificial muscles, actuators, and soft robotics. The design of bicontinuous ultralight aerogels can be extended to fabricate multifunctional and multiresponsive hybrid materials and devices.

20.
J Exp Med ; 216(4): 743-756, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30842236

RESUMO

SARM1 (sterile α and HEAT/armadillo motif-containing protein) is a member of the MyD88 (myeloid differentiation primary response gene 88) family, which mediates innate immune responses. Because inactivation of SARM1 prevents various forms of axonal degeneration, we tested whether it might protect against prion-induced neurotoxicity. Instead, we found that SARM1 deficiency exacerbates the progression of prion pathogenesis. This deleterious effect was not due to SARM1-dependent modulation of prion-induced neuroinflammation, since microglial activation, astrogliosis, and brain cytokine profiles were not altered by SARM1 deficiency. Whole-transcriptome analyses indicated that SARM1 deficiency led to strong, selective overexpression of the pro-apoptotic gene XAF1 (X-linked inhibitor of apoptosis-associated factor 1). Consequently, the activity of pro-apoptotic caspases and neuronal death were enhanced in prion-infected SARM1 -/- mice. These results point to an unexpected function of SARM1 as a regulator of prion-induced neurodegeneration and suggest that XAF1 might constitute a therapeutic target in prion disease.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Reguladoras de Apoptose/genética , Apoptose/genética , Proteínas do Domínio Armadillo/deficiência , Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , Proteínas do Citoesqueleto/deficiência , Proteínas do Citoesqueleto/metabolismo , Scrapie/metabolismo , Regulação para Cima/genética , Animais , Proteínas do Domínio Armadillo/genética , Encéfalo/metabolismo , Proteínas do Citoesqueleto/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Degeneração Neural , Isoformas de Proteínas/metabolismo , Scrapie/patologia
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