Fine particles (PM2.5) were collected using filter‐based high‐volume samplers during summer‐winter 2008 at a rural site in the central Pearl River Delta (PRD), south China, to determine typical ...secondary organic aerosol (SOA) tracers from significant biogenic (isoprene, monoterpenes, and sesquiterpenes) and anthropogenic (aromatics) precursors. Average isoprene SOA tracers were significantly higher during summer (126 ng m−3) than during fall‐winter (25.1 ng m−3), owing largely to the higher isoprene emission and reaction rates in summer. Average monoterpene SOA tracers during summer (11.6 ng m−3) and fall‐winter (16.4 ng m−3) showed much less difference compared to isoprene SOA tracers, probably resulting from the counteracting effects of temperature on the precursor emission/tracer formation and on gas/particle partitioning. The concentrations of the aromatics' SOA tracer (2,3‐dihydroxy‐4‐oxopentanoic acid) ranged from 1.70 to 52.0 ng m−3 with an average of 15.1 ng m−3, which was the highest reported in ambient air. The secondary organic carbon (SOC) estimated by the SOA‐tracer method averaged 3.07 μg C m−3 in summer and 2.00 μg C m−3 in fall‐winter, contributing 38.4% and 8.7% to OC, respectively. During summer, aromatics‐SOC and isoprene‐SOC reached 2.25 ± 1.5 μg C m−3 and 0.64 ± 0.7 μg C m−3 and accounted for 76% and 18% of the estimated SOC, respectively, while during fall‐winter, aromatics‐SOC (1.64 ± 1.4 μg C m−3) was dominant with a share of 79% in total estimated SOC. These results indicated that anthropogenic aromatics were dominant SOC precursors in the highly industrialized and urbanized PRD region. During summer, SOC levels estimated by elemental carbon (EC) tracer method were not only consistent with but also correlated well with those by SOA‐tracer method. During fall‐winter, however, SOC by SOA‐tracer method was only about one third of that by EC‐tracer method. Their gaps were significantly correlated with the biomass burning tracer levoglucosan, indicating that input from biomass burning emission with very high ratios of OC/EC during fall‐winter would result in an overestimate of SOC by EC‐tracer method. Therefore cautions should be taken when estimating SOC by EC‐tracer method, especially when biomass burning exhibits significant influences.
Key Points
Distinct seasonal trend observed for isoprene SOA tracers, but not so for others
Aromatics were dominant SOA precursors in the PRD region
EC‐tracer method overestimated SOC due to input from biomass burning aerosols
Mixed‐matrix membranes (MMMs) have the potential for energy‐efficient gas separation by matching the superior mass transfer and anti‐plasticization properties of the fillers with processability and ...scaling up features of the polymers. However, construction of high‐performance MMMs has been prohibited due to low filler‐loading and the existence of interfacial defects. Here, high MOF‐loaded, i.e., 55 wt %, MMMs are developed by a ‘dormancy and double‐activation’ (DDA) strategy. High MOF precursor concentration suppresses crystallization in the membrane casting solution, realizing molecular level mixing of all components. Then, the polymeric matrix was formed with uniform encapsulation of MOF nutrients. Subsequently, double‐activation was employed to induce MOF crystallization: the alkali promotes MOFs nucleation to harvest small porous nanocrystals while excessive ligands activate the metal ions to enhance the MOFs conversion. As such, quasi‐semi‐continuous mass transfer channels can be formed in the MMMs by the connected MOFs nanocrystals to boost the gas permeability. The optimized MMM shows significantly ameliorated CO2 permeability, i.e., 2841 Barrer, five‐fold enhancement compared with pristine polymer membrane, with a good CO2/N2 selectivity of 36. Besides, the nanosized MOFs intensify their interaction with polymer chains, endowing the MMMs with good anti‐plasticization behaviour and stability, which advances practical application of MMMs in carbon capture.
A facile and efficient ‘dormancy and double‐activation’ strategy was demonstrated to construct highly ZIF‐8‐loaded MMM with quasi‐semi‐continuous channels for rapid CO2 transportation.
Mesenchymal stem cells (MSCs) are promising candidates for cell-based therapies. Human platelet lysate represents an efficient alternative to fetal bovine serum for clinical-scale expansion of MSCs. ...Different media used in culture processes should maintain the biological characteristics of MSCs during multiple passages. However, bone marrow-derived MSCs and adipose tissue-derived MSCs have not yet been directly compared with each other under human platelet lysate conditions. This study aims to conduct a direct head-to-head comparison of the biological characteristics of the two types of MSCs under human platelet lysate-supplemented culture conditions for their ability to be used in regenerative medicine applications.
The bone marrow- and adipose tissue-derived MSCs were cultured under human platelet lysate conditions and their biological characteristics evaluated for cell therapy (morphology, immunophenotype, colony-forming unit-fibroblast efficiency, proliferation capacity, potential for mesodermal differentiation, secreted proteins, and immunomodulatory effects).
Under human platelet lysate-supplemented culture conditions, bone marrow- and adipose tissue-derived MSCs exhibited similar fibroblast-like morphology and expression patterns of surface markers. Adipose tissue-derived MSCs had greater proliferative potential than bone marrow-derived MSCs, while no significantly difference in colony efficiency were observed between the two types of cells. However, bone marrow-derived MSCs possessed higher capacity toward osteogenic and chondrogenic differentiation compared with adipose tissue-derived MSCs, while similar adipogenic differentiation potential wase observed between the two types of cells. There were some differences between bone marrow- and adipose tissue-derived MSCs for several secreted proteins, such as cytokine (interferon-γ), growth factors (basic fibroblast growth factor, hepatocyte growth factor, and insulin-like growth factor-1), and chemokine (stem cell-derived factor-1). Adipose tissue-derived MSCs had more potent immunomodulatory effects than bone marrow-derived MSCs.
Adipose tissue-derived MSCs have biological advantages in the proliferative capacity, secreted proteins (basic fibroblast growth factor, interferon-γ, and insulin-like growth factor-1), and immunomodulatory effects, but bone marrow-derived MSCs have advantages in osteogenic and chondrogenic differentiation potential and secreted proteins (stem cell-derived factor-1 and hepatocyte growth factor); these biological advantages should be considered systematically when choosing the MSC source for specific clinical application.
Dye sensitizers play an important role in dye-sensitized solar cells (DSSCs). As a promising strategy for the design of novel porphyrin sensitizers, the asymmetric modification of the porphyrin ring ...to meso-link porphyrin sensitizer has emerged in recent years, which can improve the light-harvesting properties and enhance the electron distribution. In this work, in order to reveal the essence of the effect of unsymmetrical substitution on the performance of β-link porphyrin dyes in DSSCs, four kinds of common β-link porphyrin dyes with different structures are calculated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The electronic structures and optical properties of these studied dyes in dimethylformamide (DMF) are also investigated. The key parameters of the short-circuit current density (J
), including light harvesting efficiency (LHE), electron injection driving force (ΔG
), and intra-molecular charge transfer (ICT) are discussed in detail. In addition, the periodic DFT calculations in the dye-TiO
systems are also employed to investigate the geometrical and electronic injection process of the different connection types of these studied dyes adsorbed on the periodic TiO
model with an exposed anatase (101) surface. We expect the present study would deepen the understanding of the alternative function of unsymmetrical substitution and may contribute to future DSSC design.
Two-dimensional (2D) materials have been widely used to construct efficient molecular sieving and transport channels in membrane separation. However, controlling the architecture and properties of ...the separation channel is still a great challenge. In this study, we propose a facile and feasible approach to prepare layered double hydroxide (LDH) composite membranes on tubular ceramic substrates by using amino acids (glycine, serine and alanine) as intercalation molecules. The interlayer spacing formed in the stacked LDH nanosheets provides transport channels for water molecules, and is modified through in situ intercalation of amino acid molecules with different molecular size and hydrophilic properties. The amino acid-intercalated LDH membranes exhibited high permeance without sacrificing rejection compared with pristine LDH membranes. Particularly, the glycine-intercalated LDH composite membrane with expanded hydrophilic transport channels shows a permeance of 566 L m −2 h −1 MPa −1 and a rejection of about 98.5% towards Eriochrome Black T (EBT) molecules. The permeance is 2.2-fold higher than that of the pristine LDH membrane. Moreover, molecular simulation was also used to interpret the intercalation and separation mechanism of the LDH membranes. We anticipate that this study may extend the materials and methods to regulate and control the transport channels in membranes.
Idiopathic hypereosinophilic syndrome (IHES) is associated with various organ system dysfunctions. Neurologic abnormalities have been previously noted in this syndrome. Cerebral infarction secondary ...to occlusion of large cerebral artery is rarely reported. Here we described a patient with IHES presented progressive multiple cerebral infarctions caused by bilateral middle cerebral artery occlusion.
A 55-year-old Chinese woman presented to our hospital with acute onset of right limbs weakness and slurred speech. Laboratory tests showed a significant eosinophilia of 5.29 × 10
/L (normal, < 0.5), 49.9% of leukocytes. Brain magnetic resonance imaging (MRI) revealed multiple acute cerebral ischemic lesions. Magnetic resonance angiography (MRA) demonstrated stenosis in horizontal segment of right middle cerebral artery. A pretibial skin biopsy revealed eosinophilic infiltration around the capillaries in deep dermis and adipose tissue. The patient was given oral dual anti platelet agents and intravenous methylprednisolone. However, one week later, the patient presented significant neurological deterioration with right-sided hemiparesis and totally motor aphasia. Brain MRI and computed tomography perfusion (CTP) demonstrated new acute cerebral ischemia in left hemisphere. Digital subtraction angiography (DSA) revealed left middle cerebral artery completely occluded. The patient received a high-dose of intravenous methylprednisolone 500 mg per day and the eosinophil count quickly fell to normal within 2 days. She was transferred to a rehabilitation center and her neurological symptoms improved with modified Ranking Scale from 4 to 2.
IHES is one of the rare causes of acute ischemic stroke with large cerebral artery occlusion. An early high-dose of corticosteroids therapy should be considered in cases of IHES patients. Our case study is benefit to clinical diagnosis and treatment of cerebral infarction with IHES.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hepatitis B virus X (HBx) protein is implicated in hepatitis B virus (HBV)‐associated liver carcinogenesis. However, it remains unclear whether HBx‐expressing hepatic progenitor cells (HPCs) are ...attributed to liver tumor formation. In this study, by using HBx transgenic mice and a 3,5‐diethoxycarbonyl‐1,4‐dihydrocollidine (DDC)‐induced liver injury model, the relationship between HBx expression and tumorigenicity of HPCs was analyzed. Compared with control mice, an elevated number of EpCAM+ cells with characteristics of HPCs was observed in HBx mice after 1 month and 4 months of DDC diet feeding. All HBx transgenic mice developed liver tumors characterized by histological features of both hepatocellular carcinoma (HCC) and cholangiocarcinoma after 7 months of DDC feeding. Notably, EpCAM+ HPCs isolated from premalignant HBx mice exposed to a DDC diet for 4 months formed subcutaneous mixed‐lineage tumors (four out of six) in nonobese diabetic/severe‐combined immunodeficient (NOD/SCID) mice, and none of the cells from wildtype (WT) induced tumor, indicating that HBx may induce malignant transformation of HPCs that contributes to tumorigenesis. We also found higher titers of circulating interleukin (IL)‐6, activities of IL‐6/STAT3, and Wnt/β‐catenin signaling pathways in HBx transgenic mice, suggesting HBx may induce intrinsic changes in HPCs by way of the above signaling that enables HPCs with tumorigenicity potential. Finally, clinical evidence showed that high HBx expression in human HBV‐related HCC was statistically associated with expansion of EpCAM+ or OV6+ tumor cells and aggressive clinicopathologic features. Conclusion: HBx induces intrinsic cellular transformation promoting the expansion and tumorigenicity of HPCs in DDC‐treated mice, which may be a possible origin for liver cancer induced by chronic hepatitis infection. (HEPATOLOGY 2012)
This study delineates the role of peroxiredoxin 3 (Prx3) in hair cell death induced by several etiologies of acquired hearing loss (noise trauma, aminoglycoside treatment, age). In vivo, Prx3 ...transiently increased in mouse cochlear hair cells after traumatic noise exposure, kanamycin treatment, or with progressing age before any cell loss occurred; when Prx3 declined, hair cell loss began. Maintenance of high Prx3 levels via treatment with the radical scavenger 2,3-dihydroxybenzoate prevented kanamycin-induced hair cell death. Conversely, reducing Prx3 levels with Prx3 siRNA increased the severity of noise-induced trauma. In mouse organ of Corti explants, reactive oxygen species and levels of Prx3 mRNA and protein increased concomitantly at early times of drug challenge. When Prx3 levels declined after prolonged treatment, hair cells began to die. The radical scavenger p-phenylenediamine maintained Prx3 levels and attenuated gentamicin-induced hair cell death. Our results suggest that Prx3 is up-regulated in response to oxidative stress and that maintenance of Prx3 levels in hair cells is a critical factor in their susceptibility to acquired hearing loss.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background & Aims Due to its anatomic connection, the liver is constantly exposed to gut-derived bacterial products or metabolites. Disruption of gut homeostasis is associated with many human ...diseases. The aim of this study was to determine the role of gut homeostasis in initiation and progression of hepatocellular carcinoma (HCC). Methods Disruption of intestinal homeostasis by penicillin or dextran sulfate sodium (DSS) and its restoration by probiotics were applied in a diethylnitrosamine (DEN) model of rat hepatocarcinogenesis. Results Patients with liver cirrhosis and HCC had significantly increased serum endotoxin levels. Chronic DEN treatment of rats was associated with an imbalance of subpopulations of the gut microflora including a significant suppression of Lactobacillus species, Bifidobacterium species and Enterococcus species as well as intestinal inflammation. Induction of enteric dysbacteriosis or intestinal inflammation by penicillin or DSS, respectively, significantly promoted tumor formation. Administration of probiotics dramatically mitigated enteric dysbacteriosis, ameliorated intestinal inflammation, and most importantly, decreased liver tumor growth and multiplicity. Interestingly, probiotics not only inhibited the translocation of endotoxin, which bears pathogen-associated molecular patterns (PAMPs) but also the activation of damage-associated molecular patterns (DAMPs) such as high-mobility group box 1 (HMGB1). As a result, the production of pro- and anti-inflammatory cytokines was skewed in favor of a reduced tumorigenic inflammation in the liver. Conclusions The data highlights the importance of gut homeostasis in the pathogenesis of HCC. Modulation of the gut microbiota by probiotics may represent a new avenue for therapeutic intervention to treat or prevent HCC development.
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•A novel NF membrane building block PEC NPs armed with sulfated groups was fabricated.•Hydrophilicity and water permeability of SPECMs were enhanced.•SPECMs possessed good salt/dye ...separation and antifouling properties in a long-term process.
Polysaccharide nanofiltration (NF) membrane with traditional modification normally suffers from poor water permeability as a result of its tight packing of polymeric chains. In this work, a novel membrane building block, polyelectrolyte complex (PEC) nanoparticles (NPs) armed with adjustable content of sulfated groups was developed using chitosan and dextran sulfate sodium. The sulfated polyelectrolyte complex membranes (SPECMs) were first prepared by solution-casting and glutaraldehyde crosslinking process, and their structural characteristics and surface properties were systematically investigated. Intrinsic aggregation structure combined with numerous sulfate groups attenuates packing density of polymeric chains and promotes hydrophilicity, endowing SPECMs with high flux and perm-selectivity. SPECMs achieved a water permeability of 6.71Lm−2h−1bar−1, which was ∼2.3 times higher than pristine sulfated chitosan membrane. The selectivity for NaCl/Na2SO4 separation and NaCl/methyl blue dye separation were as high as 13.1 and 850.0, respectively. Moreover, SPECMs featured efficient dye antifouling property with low flux decline ratio (6.8%) and high recovery ratio (96.8%), which was primarily attributed to its hydrophilicity and smooth surface. The prominent perm-selectivity associated with antifouling property suitably position SPECMs for practical small organic molecule/inorganic salt mixture separation in a long-term process.
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