The glacial-terrestrial-fluvial pathway: A multiparametrical analysis of spatiotemporal dissolved organic matter variation in three catchments of Lake Nam Co, Tibetan Plateau.

The Tibetan Plateau (TP) is a sensitive alpine environment of global importance, being Asia's water tower, featuring vast ice masses and comprising the world's largest alpine grasslands. Intensified land-use and pronounced global climate change have put pressure on the environment of the TP. We studied the tempo-spatial variability of dissolved organic matter (DOM) to better understand the fluxes of nutrients and energy from terrestrial to aquatic ecosystems in the TP. We used a multiparametrical approach, based on inorganic water chemistry, dissolved organic carbon (DOC) concentration, dissolved organic matter (DOM) characteristics (chromophoric DOM, fluorescence DOM and δ13C of DOM) in stream samples of three catchments of the Nam Co watershed and the lake itself. Satellite based plant cover estimates were used to link biogeochemical data to the structure and degradation of vegetation zones in the catchments. Catchment streams showed site-specific DOM signatures inherited from glaciers, wetlands, groundwater, and Kobresia pygmaea pastures. By comparing stream and lake samples, we found DOM processing and unification by loss of chromophoric DOM signatures and a change towards an autochthonous source of lake DOM. DOM diversity was largest in the headwaters of the catchments and heavily modified in terminal aquatic systems. Seasonality was characterized by a minor influence of freshet and by a very strong impact of the Indian summer monsoon on DOM composition, with more microbial DOM sources. The DOM of Lake Nam Co differed chemically from stream water samples, indicating the lake to be a quasi-marine environment in regards to the degree of chemical modification and sources of DOM. DOM proved to be a powerful marker to elucidate consequences of land use and climatic change on biogeochemical processes in High Asian alpine ecosystems.

Graphene Oxide and Graphene Oxide-TiO2 Nanocomposites: Synthesis, Characterization, and Rhodamine B Photodegradation Investigation.

In this study, graphene oxide (GO) sheets were successfully synthesized using two routes: conventional Hummers' (HGO) and modified Hummers' (or Marcano's) (MGO) methods. GO sheets were then assembled with TiO2 nanoparticles to form nanocomposites (i.e., HGO-TO and MGO-TO). The properties of HGO and MGO and their nanocomposites with TiO2 were evaluated by Fouriertransform infrared (FTIR), Raman, ultraviolet-visible (UV-Vis) adsorption, and diffuse reflectance (DRS) spectroscopies, X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The specific surface area, pore volume, and pore size of MGO, determined by Brunauer-Emmett-Teller (BET) equation, were 565 m²g-1, 376 cm³ g-1, and 30 nm, respectively; all of these parameters decreased after MGO was combined with TiO2. In addition, compared with HGO, MGO possessed higher oxidation level and more stable bonding with TiO2 nanoparticles. The morphology of HGO and MGO, which were characterized by scanning electron (SEM) and transmission electron microscopies (TEM), together with energy-dispersive X-ray (EDX) spectroscopy and elemental mapping technique, was determined to consist of TiO2 nanoparticle-assembled GO sheets. All GO-TiO2 nanocomposite samples exhibited a very high activity (˜100%) toward rhodamine B (RhB) dye photodegradation under natural sunlight exposure within 60 min. The obtained results for the GO-TiO2 nanocomposite showed the potential of its application in wastewater purification and other environmental aspects.

Evolution and present scenario of multifunctionalized mesoporous nanosilica platform: A mini review.

The development of nanomaterials in the field of biomedical has attracted much attention in the past decades. New mesoporous nanosilica (MNS) generation, called multi functionalized MNS, presents the promising applications for efficient encapsulation, controlled release, and intracellular delivery of therapeutic agents due to their unique physiochemical properties, such as large surface area and pore volume, tunable particle size, biocompatibility, and high loading capacity. In this review, we intensively discussed the multi functionalized MNSs that respond to the demand of physical stimuli (thermo, light, magnetic field, ultrasound, and electricity), chemical stimuli (pH, redox, H2O2), and biological stimuli (enzyme, glucose, ATP), individual or in combination. Moreover, the recent applications of multi functionalized MNSs, focusing on drug and other therapeutic agents delivery, diagnostic imaging, and catalysis are also summarized in order to promote the further development of MNSs as a universal platform in the bright upcoming future.

Preparation, Characterization and Antifungal Properties of Chitosan-Silver Nanoparticles Synergize Fungicide Against Pyricularia oryzae.

Rice (Oryza sativa L.) is one of the major staple food crops of nearly two-third of the world's population. However, rice blast caused by fungus Pyricularia oryzae is generally considered the most serious disease of cultivated rice worldwide due to its extensive distribution and destructiveness under favourable climatic conditions. In this report, the combination between chitosan (CS) and silver (Ag), Ag@CS, was introduced for antifungal activity against Pyricularia oryzae extracted from blast-infected leaves. In detail, Ag@CS nanoparticles (NPs) were first synthesized and further mixed with Trihexad 700 WP (Tri), Ag@CS-Tri, against the fungus by agar diffusion method. The prepared Ag@CS-Tri NPs were characterized by Fourier transform infrared (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). In aqueous condition, Ag@CS-Tri NPs were successfully prepared and existed as spherical NPs with particle size of 17.26 ± 0.89 nm, which is an ideal size for their uptake into plant cells, indicating that the size of their parentally Ag@CS NPs is small enough to combine Tri, and their diameter is large enough to effectively penetrate the cellular membrane and kill fungi. More importantly, the antifungal property of Ag@CS-Tri NPs was significantly increased with inhibition zone around 25 nm compared with only around 12 nm of Ag@CS at the same concentration of Ag (2 ppm) and CS (4000 ppm). These results demonstrated that the synergistic effect of Tri and Ag@CS NPs can be a potential candidate with high antifungal activity for the use of antibiotics in agriculture.

Low systemic toxicity nanocarriers fabricated from heparin-mPEG and PAMAM dendrimers for controlled drug release.

In this report, poly(amide amine) (PAMAM) dendrimer and Heparin-grafted-monomethoxy polyethylene glycol (HEP-mPEG) were synthesized and characterized. In aqueous solution, the generation 4 PAMAM dendrimers (G4.0-PAMAM) existed as nanoparticles with particle size of 5.63nm. However, after electrostatic complexation with HEP-mPEG to form a core@shell structure G4.0-PAMAM@HEP-mPEG, the size of nanoparticles was significantly increased (73.82nm). The G4.0-PAMAM@HEP-mPEG nanoparticles showed their ability to effectively encapsulate doxorubicin (DOX) for prolonged and controlled release. The cytocompatibility of G4.0-PAMAM@HEP-mPEG nanocarriers was significantly increased compared with its parentally G4.0-PAMAM dendrimer in both mouse fibroblast NIH3T3 and the human tumor HeLa cell lines. DOX was effectively encapsulated into G4.0-PAMAM@HEP-mPEG nanoparticles to form DOX-loaded nanocarriers (DOX/G4.0-PAMAM@HEP-mPEG) with high loading efficiency (73.2%). The release of DOX from DOX/G4.0-PAMAM@HEP-mPEG nanocarriers was controlled and prolonged up to 96h compared with less than 24h from their parentally G4.0-PAMAM nanocarriers. Importantly, the released DOX retained its bioactivity by inhibiting the proliferation of monolayer-cultured cancer HeLa cells with the same degree of fresh DOX. This prepared G4.0-PAMAM@HEP-mPEG nanocarrier can be a potential candidate for drug delivery systems with high loading capacity and low systemic toxicity in cancer therapy.

Clinical Application of the QRS-T Angle for the Prediction of Ventricular Arrhythmias in Patients with the Fontan Palliation.

Fontan palliation patients are at risk for ventricular arrhythmias post-operatively. This study aimed to evaluate whether differences in the spatial QRS-T angle can reliably predict ventricular arrhythmias in patients who had undergone Fontan palliation. A total of 117 patients who had the Fontan palliation and post-Fontan catheterization were included. Ventricular arrhythmias were identified in nine patients. Measurements of ECG parameters including QRS vector magnitude, QRS duration, corrected QT interval, and spatial peaks QRS-T angles were performed, and compared between those with and without ventricular arrhythmias. The only ECG parameter to distinguish those with versus those without VA was the SPQRS-T angle (p < 0.001), which at a cut-off value of 102.9° gave sensitivity, specificity, positive and negative predictive values of 100.0, 57.0, 17.6 and 100.0%, respectively. Only the spatial peaks QRS-T angle differentiated those with and without ventricular arrhythmia development with a univariate HR 1.237 (95% CI 1.021-1.500) and a multivariate HR of 1.032 (1.009-1.056) when catheter measured parameters were taken into account. In Fontan patients, the spatial peaks QRS-T angle is a significant independent predictor of ventricular arrhythmias. Clinical usefulness of this parameter remains to be seen and should be tested prospectively.

Hierarchical self-assembly of heparin-PEG end-capped porous silica as a redox sensitive nanocarrier for doxorubicin delivery.

Porous nanosilica (PNS) has been attracting a great attention in fabrication carriers for drug delivery system (DDS). However, unmodified PNS-based carriers exhibited the initial burst release of loaded bioactive molecules, which may limit their potential clinical application. In this study, the surface of PNS was conjugated with adamantylamine (A) via disulfide bonds (PNS-SS-A) which was functionalized with cyclodextrin-heparin-polyethylene glycol (CD-HPEG) for redox triggered doxorubicin (DOX) delivery. The modified PNS was successfully formed with spherical shape and diameter around 50nm determined by transmission electron microscopy (TEM). DOX was efficiently trapped in the PNS-SS-A@CD-HPEG and slowly released in phosphate buffered saline (PBS) without any initial burst effect. Importantly, the release of DOX was triggered due to the cleavage of the disulfide bonds in the presence of dithiothreitol (DTT). In addition, the MTT assay data showed that PNS-SS-A@CD-HPEG was a biocompatible nanocarrier and reduced the toxicity of DOX. These results demonstrated that PNS-SS-A@CD-HPEG has great potential as a novel nanocarrier for anticancer drug in cancer therapy.