Weak Reduction Research Articles

Behavioral Changes of Multipotent Mesenchymal Stromal Cells in Contact with Synthetic Calcium Phosphates in vitro

Migration, proliferation, and osteogenic differentiation of human adipose-derived (AD) multipotent mesenchymal stromal cells (MMSCs) during in vitro modeling of indirect contact with calcium phosphate (CP) or nanoparticles of synthetic hydroxyapatite (HA) have been studied. The results were registered with electrode (real-time cell analysis, RTCA) or visual (Cell-IQ) systems of long-term observation of cell cultures. Bulk specimens were use in a Cell-IQ® v2 MLF device as pure titanium substrates (10 × 10 × 1 mm3) covered by a CP relief (roughness index Ra = 2.4–4.4 μm) bilateral coating that was prepared by the micr-arc method from an aqueous solution of orthophosphoric acid (20 wt %), calcium carbonate (9 wt %), and synthetic HA (6 wt %). HA crystallites (1 mg/mL) were fabricated by mechanochemical synthesis and served as an irritant in RTCA investigation. The Cell-IQ system identified a 3.5- to 10-fold decrease in cell number at the interface with CP coatings with differing roughness during 14-day cell culturing. After 21 days, it was accompanied by a weak reduction of MMSC antigen expression (CD73, CD90, and CD105) as opposed to an increase in MMSC osteogenic differentiation and intercellular-matrix mineralization. In turn, HA nanodispersion reduced the speed of MMSC migration by 1.5 times (P < 0.001) during 25-h RTCA recording, which simulated cell invasion through the microporous membrane (8-μm diameter). Inhibition of migration and cell division with increased osteogenic differentiation of MMSCs has been suggested to be a possible effect of biodegradation products of synthetic CP materials.

Spectroscopic ellipsometry studies on microstructure evolution of a-Si:H to nc-Si:H films by H2 plasma exposure

This paper presents the influence of hydrogen plasma treatment on the growth of nano crystalline silicon phase in a-SiH films. Series of hydrogenated amorphous silicon films were prepared by PECVD technique with intermittent hydrogen plasma treatment for 5 min each time followed by silane plasma, keeping the total silane plasma time fixed at 60 min. The evolution of nanocrystalline Si phase due to intermittent hydrogen plasma treatment is studied through Spectroscopic Ellipsometry(SE), Raman and FTIR absorption spectroscopy. Dielectric function obtained from the SE measurements was used to determine the optical constant, thickness and band gap of the films. The hydrogen plasma treated films have less void fraction and higher density. The growth of nanocrystalline phase is enhanced due to etching of weak SiSi bonds and reduction in bonding disorder during hydrogen plasma. Hydrogen plasma treatment results in nc-Si:H films at high deposition rate and low substrate temperature.

EUV Bragg reflectors with photonic superlattices

The basic properties in the extreme ultraviolet (EUV) of one-dimensional photonic crystals (Bragg reflectors) with incorporated superlattices are investigated by a numerical study using the multiple scattering method. The superlattice is realized in the “standard” Mo/Si system by periodically replacing certain Mo layers by Si layers. At 13.5 nm–the wavelength of interest for EUV lithography–the superlattice sharpens the reflection peak at normal incidence with only weak reduction of the peak value. Between normal incidence and total reflection at large angles, additional reflection peaks appear at certain angles where the reflection is zero for the “standard” Mo/Si system. By combining different superlattices and depth grading, the range of additional reflection peaks is extended towards all-angle reflection. The effect of interface imperfections is considered for the case of the interdiffusion of Mo and Si. The extension to other frequency ranges is addressed via band structure calculations.

The Atypical Guanylate Kinase MoGuk2 Plays Important Roles in Asexual/Sexual Development, Conidial Septation, and Pathogenicity in the Rice Blast Fungus.

Guanylate kinases (GKs), which convert guanosine monophosphate into guanosine diphosphate (GDP), are important for growth and mannose outer chain elongation of cell wall N-linked glycoproteins in yeast. Here, we identified the ortholog of Saccharomyces cerevisiae GK Guk1, named MoGuk1 and a novel family of fungal GKs MoGuk2 in the rice blast fungus Magnaporthe oryzae. MoGuk1 contains 242 aa with an C-terminal GuKc domain that very similar to yeast Guk1. MoGuk2 contains 810 amino acids with a C-terminal GuKc domain and an additional N-terminal efThoc1 domain. Expression of either MoGuk1 or MoGuk2 in heterozygote yeast guk1 mutant could increase its GDP level. To investigate the biological role of MoGuk1 and MoGuk2 in M. oryzae, the gene replacement vectors were constructed. We obtained the ΔMoguk2 but not ΔMoguk1 mutant by screening over 1,000 transformants, indicating MoGuk1 might be essential for M. oryzae. The ΔMoguk2 mutant showed weak reductions in vegetative growth, conidial germination, appressorial formation, and appressorial turgor, and showed significant reductions in sporulation and pathogenicity. Moreover, the ΔMoguk2 mutant failed to produce perithecia and was sensitive to neomycin and a mixture of neomycin-tunicamycin. Exogenous GDP and ATP partially rescued the defects in conidial germination, appressorial formation, and infectious growth of the mutant. Further analysis revealed that intracellular GDP and GTP level was decreased, and GMP level was increased in the mutant, suggesting that MoGuk2 exhibits enzymatic activity. Structural analysis proved that the efThoc1, GuKc, and P-loop domains are essential for the full function of MoGuk2. Taken together, our data suggest that the guanylate kinase MoGuk2 is involved in the de novo GTP biosynthesis pathway and is important for infection-related morphogenesis in the rice blast fungus.

Indication of rare earth element characteristics to dolomite petrogenesis—A case study of the fifth member of Ordovician Majiagou Formation in the Ordos Basin, central China

Abstract Rare earth elements (REEs), as important geochemical tracers, can well reflect the information carried by diagenetic fluids. In this paper, petrological and REE characteristics are studied to investigate diagenetic fluid information and dolomite petrogenesis using samples from the fifth member of Ordovician Majiagou Formation (Ma5) in the Ordos Basin based on the comprehensive analysis of C, O, and Sr isotopes. Three types of dolomites are identified in the study area, namely the dolomicrite, micrite-silty dolomite, and silty dolomite. Different types of dolomites have distinct total REE contents, among which the dolomicrite has the highest average total REE content and that could be possibly attributed to the abundant algal and argillaceous materials. All the three types of dolomites are featured by lower total contents of REEs than marine micrite, enriched light rare earth elements (LREEs) and deficit heavy rare earth elements (HREEs), which could result from the constant diffusion of REEs in the late diagenetic environment as well as the stronger complexing capacity of HREEs than LREEs. REE partition patterns in three types of dolomites are similar to those in marine micrite, which indicate the dolomitization fluids to be seawater or marine-origin fluids. In the dolomicrite, an obvious negative Eu anomaly (average value 0.63) and a faint negative Ce anomaly (average value 0.94) suggest that the sedimentary environment should be featured by low temperature and weak oxidation. Meanwhile, negative δ13C excursion (average value - 1.23‰), positive δ18O excursion (average value −7.59‰), and high mean 87Sr/86Sr ratios (average value 0.70992) along with petrological characteristics demonstrate the dolomicrite to originate from penecontemporaneous dolomitization. In the micrite-silty dolomite, the obvious negative Eu anomaly (average value 0.69) and the medium negative Ce anomaly (average value 0.72) indicate such kind of dolomites should be formed in the sedimentary environment characterized by low temperature and weak oxidation-weak reduction. The negative δ13C excursion (average value −0.43‰), positive δ18O excursion (average value −7.29‰), and relatively low mean 87Sr/86Sr ratios (average value 0.70955) identify the micrite-silty dolomite to be product of seepage reflux dolomitization in the supratidal zone. In the silty dolomite, the weakened negative Eu anomaly (average value 0.75) indicates relatively high temperature, and the obvious negative Ce anomaly (average value 0.66) implies reducing environment. Based on analysis of values of δ13C (average value −0.65‰) and δ18O (average value −6.46‰) as well as ratios of 87Sr/86Sr (average value 0.70958), silty dolomite is regarded to form due to burial dolomitization.

Reconfigurable band‐rejection antenna for ultra‐wideband applications

A low-profile, low cost reconfigurable antenna with on-demand single- or dual-band rejection capability for ultra-wideband (UWB) applications is presented. A modified monopole structure is integrated with an arc-shaped slot and two open-ended L-shaped stubs to realise the band rejection. The antenna operates in four modes: a full UWB (3.1-10.6 GHz) coverage antenna, a UWB antenna with a single-band WiMax or wide local area network (WLAN) rejection, and a UWB antenna with dual-band WiMax/WLAN rejection. On-demand individual and simultaneous band-rejections are implemented by controlling the arc-slot and L-stubs using three PIN diodes. Thus, the adopted control technique is quite easy and requires low operational power (approximately 40 mW max.). Details of the design process and reconfiguration mechanism are presented. The band-rejection function is explained using equivalent circuits and surface current distribution at each mode. A prototype is built on the FR4 substrate and tested to validate the performances. The antenna exhibits stable radiation characteristics and almost flat gain (average 4 dBi) responses across the whole band, while significantly weak radiation and gain reduction (;7 dB) are achieved at the rejected bands. Therefore, this antenna is suitable for high-performance UWB systems in WiMax/WLAN dense environments with the aim to improve signal quality, system capacity, and communication link efficiency.

Some Features of the Environmental Strategy of Tulipa gesneriana L. (Liliaceae, Liliopsida)

The vitality of 31 natural populations of Tulipa gesneriana is based on our field surveys that were conducted in several parts of European Russia from 2013 to 2015. The basic factors that affect the vitality of the T. gesneriana population were revealed according to the results of the analysis of 14 morphological parameters of T. gesneriana. Cattle grazing was the most essential factor. The effect of other negative factors is much lower. On the whole, the mixed stress-tolerant and ruderal ecological cenotic strategy is characteristic of the species. For instance, an increase in the stress level leads to a decrease in the size of all aboveground organs, which is accompanied by considerable variations in the height and diameter of plants. However, most of the parameters, on the contrary, have a weak reduction in their variability under stress. All these features indicate a comparatively narrow ecological amplitude of the species investigated.

Children with Williams syndrome make music: A community-based care model in the Czech Republic

Abstract The Williams syndrome (WS) is a multifactorial genetic disorder that results from a deletion on location 7q11.23 and is characterized by a broad spectrum of pathological features. The strong affinity of affected individuals to music inspires promising therapeutic and community-based activities with instruments and the voice. Children with WS display an extraordinarily creative behaviour and have an eyecatching, outgoing personality. On the basis of a short review of research dedicated to music processing and music-associated benefits in WS, this article presents community-based music therapeutic approaches in Prague/Czech Republic. Taking sociocultural aspects of acculturation into account, it also discusses the multifaceted role of music therapists. Professional community music (CM) practice with WS encompasses manifold benefits such as social inclusion, developmental progress and personal growth, reduction of symptom-associated weakness, and subjective wellbeing through cultural participation.

Structure and Affinity of Cu(I) Bound to Human Serum Albumin.

Human serum albumin (HSA) is a major Cu carrier in human blood and in cerebrospinal fluid. A major assumption is that Cu bound to HSA is in the Cu(II) oxidation state; thus, interactions between HSA and Cu(II) have been intensely investigated for over four decades. HSA has been reported previously to support the reduction of Cu(II) to the Cu(I) oxidation state in the presence of the weak reductant, ascorbate; however, the interactions between HSA and Cu(I) have not been explicitly investigated. Here, we characterize both the apparent affinity of HSA for Cu(I) using solution competition experiments and the coordination structure of Cu(I) bound to HSA using X-ray absorption spectroscopy and in silico modeling. We find that HSA binds to Cu(I) at pH 7.4 with an apparent conditional affinity of KCu(I):HSA = 1014.0 using digonal coordination in a structure that is similar to the bis-His coordination modes characterized for amyloid beta (Aβ) and the prion protein. This high affinity and familiar Cu(I) coordination structure suggests that Cu(I) interaction with HSA in human extracellular fluids is unappreciated in the current scientific literature.

In situ Weak Magnetic-Assisted Thermal Stress Field Reduction Effect in Laser Welding

For decades, post-welding magnetic treatment has been used to reduce residual stress of welds by improving the crystal structure of solid-state welds. In this paper, we propose a new magnetic treatment method, which can reduce the time-dependent thermal stress field in situ and reduce the final residual stress of welds by simply exerting an assisted weak magnetic field perpendicular to the welding direction and workpiece during laser welding. A new finite-element model is developed to understand the thermal–mechanical physical process of the magnetic-assisted laser welding. For the widely used 304 austenite stainless steel, we theoretically observed that this method can reduce around 10 pct of the time-dependent thermal stress field, and finally reduce approximately 20 MPa of residual stress near the heat-affected zone with a 415-mT magnetic field for typical welding process parameters. A new mechanism based on magneto-fluid dynamics is proposed to explain the theoretical predications by combining high-speed imaging experiments of the transient laser welding process. The developed method is very simple but surprisingly effective, which opens new avenues for thermal stress reduction in laser welding of metals, particularly heat-sensitive metallic materials.

Extraction chromatography–electrodeposition (EC–ED) process to recover palladium from high-level liquid waste

The extraction chromatography–electrodeposition (EC–ED) process was proposed for the quantitative recovery of palladium from high-level liquid waste (HLLW) in this study. The process coupled the extraction chromatography method to obtain the decontamination of Pd(II) from HLLW with the electrochemical method to recover metallic palladium from the concentrated solution. Separation of Pd(II) from a nitric acid medium by extraction chromatography using isoBu-BTP/SiO2-P adsorbent and the electrochemical behavior of Pd(II) in nitric acid solution in the presence of thiourea (TU) were investigated. isoBu-BTP/SiO2-P exhibited a high selectivity for Pd(II) over other fission products (FPs), and Pd(II) could be desorbed by TU from loaded BTP/SiO2-P. The adsorbent performed good stability against HNO3 because the adsorption performance kept Pd(II) after extended contact with HNO3 solution. The column experiment achieved the separation of Pd(II) from simulated HLLW successfully. The electrochemical behavior of Pd(II) in palladium desorption solution containing TU and nitric acid was investigated at a platinum electrode by cyclic voltammetry. A weak reduction wave at − 0.4 V was due to the reduction in Pd(II) to Pd(0), and the deposition process was irreversible. In electrowinning experiments, a maximum of 92% palladium could be obtained.

Herpes simplex virus-1 entrapped in Candida albicans biofilm displays decreased sensitivity to antivirals and UVA1 laser treatment

BackgroundRecently, we published data suggesting a mutualistic relationship between HSV-1 and Candida. albicans; in particular: (a) HSV-1 infected macrophages are inhibited in their anti-Candida effector function and (b) Candida biofilm protects HSV-1 from inactivation. The present in vitro study is aimed at testing the effects of Candida biofilm on HSV-1 sensitivity to pharmacological and physical stress, such as antiviral drugs (acyclovir and foscarnet) and laser UVA1 irradiation. We also investigated whether fungus growth pattern, either sessile or planktonic, influences HSV-1 sensitivity to antivirals.MethodsMature Candida biofilms were exposed to HSV-1 and then irradiated with laser light (UVA1, 355 λ). In another set of experiments, mature Candida biofilm were co-cultured with HSV-1 infected VERO cells in the presence of different concentrations of acyclovir or foscarnet. In both protocols, controls unexposed to laser or drugs were included. The viral yield of treated and untreated samples was evaluated by end-point titration. To evaluate whether this protective effect might occur in relation with a different growth pattern, HSV-1 infected cells were co-cultured with either sessile or planktonic forms of Candida and then assessed for susceptibility to antiviral drugs.ResultsUVA1 irradiation caused a 2 Log reduction of virus yield in the control cultures whereas the reduction was only 1 Log with Candida biofilm, regardless to the laser dose applied to the experimental samples (50 or 100 J/cm2). The presence of biofilm increased the IC90 from 18.4–25.6 J/cm2. Acyclovir caused a 2.3 Log reduction of virus yield in the control cultures whereas with Candida biofilm the reduction was only 0.5 Log; foscarnet determined a reduction of 1.4 Log in the controls and 0.2 Log in biofilm cultures. Consequently, the ICs50 for acyclovir and foscarnet increased by 4- and 12-folds, respectively, compared to controls. When HSV-1 was exposed to either sessile or planktonic fungal cells, the antiviral treatments caused approximately the same weak reduction of virus yield.ConclusionsThese data demonstrate that: (1) HSV-1 encompassed in Candida biofilm is protected from inactivation by physical (laser) and pharmacological (acyclovir or foscarnet) treatments; (2) the drug antiviral activity is reduced at a similar extent for both sessile or planktonic Candida.

Iron geochemistry and organic carbon preservation by iron (oxyhydr)oxides in surface sediments of the East China Sea and the south Yellow Sea

Abstract In marine sediments factors that influence iron (Fe) geochemistry and its interactions with other elements are diverse and remain poorly understood. Here we comparatively study Fe speciation and reactive Fe-bound organic carbon (Fe-OC) in surface sediments of the East China Sea (ECS) and the south Yellow Sea (SYS). The objectives are to better understand the potential impacts of geochemically distinct sediment sources and depositional/diagenetic settings on Fe geochemistry and OC preservation by Fe (hydr)oxides in sediments of the two extensive shelf seas around the world. Contents of carbonate- and acid-volatile-sulfide (AVS)-associated Fe(II) (FeAVS + carb) and magnetite (Femag) in the ECS sediments are about 5 and 9 times higher, respectively, than in the SYS. This could be ascribed to the ferruginous conditions of the ECS sediments that favor the formation/accumulation of Fecarb and Femag, a unique feature of marine unsteady depositional regimes. Much lower total Fe(II) contents in the SYS than in the ECS suggest that lower availability of highly reactive Fe (FeHR) and/or weak Fe reduction is a factor limiting Fe(II) formation and accumulation in the SYS sediments. The ratio of FeHR to total Fe is, on average, markedly higher (2.4 times) in the ECS sediments than in the SYS, which may be a combined result of several factors relevant to different sediment sources and depositional/diagenetic settings. In comparison with many other marine sediments, the percent fractions (fFe-OC) of Fe-OC to total organic carbon (TOC) in the ECS and the SYS are low, which can be ascribed to surface adsorption of OC rather than coprecipitation or organic complexation as the dominant binding mechanisms. Based on the fFe-OC in this study, total Fe-OC estimated for global continental shelves is equivalent to 38% of the atmospheric CO2 pool, which indicates the important role of sorptive stabilization of Fe-OC in continental shelf sediments for buffering CO2 release to the atmosphere. In the SYS, consistently less 13C-depleted Fe-OC relative to 13C of non-Fe-bound OC (13Cnon-Fe-OC) suggests selective sequestration of labile marine OC in the marine OC-dominated sediments of the central SYS. In the ECS, however, efficient oxidation of OC and frequent redox cycling of Fe in the unsteady depositional regimes may complicate the isotopic compositions of Fe-OC. A combination of our results and literature data demonstrates that Fe-OC contents are strongly dependent on the availability of TOC and reactive Fe, but the fFe-OC is primarily controlled by the processes of Fe redox cycling in the sediments.

PCR Identification of Aspergillus niger with Using Natural Additives for Controlling and Detection of Malformins and Maltoryzine Production by HPLC

Nowadays, it has been difficult to control exposure of humans to fungal toxic metabolites, because these metabolites naturally occur in the environment. Therefore, the use of natural compounds like essential oils, besides biocontrol than that of synthetic products, can be a good alternative for addressing this problem. Seven fungal species belonging to four genera were isolated from ten samples of wheat grains randomly collected from Jazan Region, Saudi Arabia, with using the direct plating technique. Because Aspergillus niger was the most distributed and the most frequent fungus in wheat grains, therefore their identification was confirmed by PCR and tested for production of malformin A, malformin C, and maltoryzine in synthetic and natural media, besides using safe additive essential oils (EOs) for controlling these toxic metabolites production. Productivities of malformin A, malformin C, and maltoryzine were 13.4 ± 0.00, 9.6 ± 0.05, and 0.37 ± 0.00 μg/l synthetic medium compared with 17.4 ± 0.18, 11.9 ± 0.05, and 0.49 ± 0.01 μg/l natural medium, respectively. Malformin A, malformin C, and maltoryzine production was suppressed by neem oil, where production inhibition percent were 45.98, 47.89, and 51.01 on natural compared to 29.85, 29.16, and 35.13% on synthetic media for malformin A, malformin C, and maltoryzine, respectively, at 7.50% (v/v) neem oil. With using oregano EO 7.50% (v/v), inhibitions of malformin A, malformin C, and maltoryzine production were 44.77, 46.88 and 67.57% on synthetic growth medium, and 45.98, 38.65 and 51.02%, respectively, on natural medium. A weak remarkable reduction of these toxin syntheses was observed with using fenugreek EO compared with the other used oils.

Antiproliferative Properties Against Human Breast, Cervical and Ovarian Cancer Cell Lines, and Antioxidant Capacity of Leaf Aqueous Ethanolic Extract from Cotinus coggygria Scop.

Abstract Cotinus coggygria Scop. leaf aqueous ethanolic extract was examined for its in vitro antiproliferative and antioxidant activity. Antiproliferative effect was assessed on four human gynecological cancer cell lines: breast (MCF7, T47D), cervical (HeLa) and ovarian (A2780) and compared to the cell growth inhibitory effect on non-cancerous breast epithelial cell line MCF10A using MTT cell proliferation assay. Radical scavenging assay with DPPH was applied to evaluate antioxidant potential of the extract. The obtained results showed that the herb inhibited cell growth of all of the tested cancer cell lines and the highest was the cytostatic effect on A2780 cells with a half maximal inhibitory concentration (IC50) value of 30.8 μg/ml. For the other cell lines the IC50 values were in the range of 55-122.7 μg/ml. Additionally, the extract exerted considerably weaker reduction in cell proliferation of the non-cancerous cell line MCF10A compared to cancer cells, which indicates for antiproliferative selectivity. C. coggygria extract showed high free radical scavenging activity with an IC50 value of 11.2 μg/ml. The obtained data provide evidence for pharmacological potential of the tested extract and future more detailed studies concerning the molecular mechanisms of the anticancer effect of the herb are needed.

Numerical simulation of heat and mass transfer in a 3D model of a loop heat pipe evaporator

The article presents results of 3D numerical simulation of flow and conjugate heat and mass transfer in a model of the TacSat-4 satellite loop heat pipe evaporator. The mathematical model includes the Reynolds-averaged Navier–Stokes equations describing the flow in the liquid and vapor regions, Darcy's law for filtration modeling in the wicks and the energy equation with accurate coupling of connected sub-domains including effects of evaporation on interfaces between the porous and vapor regions. According to the simulation results, the evaporation localizes mainly at the vapor groove corners near the evaporator body. The vapor grooves operate under essentially different conditions, as a result, the flow rates differ by several times. Significant thickening of the evaporator body yields only weak reduction in a level of the grooves’ flow rate non-uniformity.

Influence of the preparation conditions ofPd‐ZrO2andAuPd‐ZrO2nanoparticle–decorated functionalisedMWCNTs: Electron spectroscopy study aided with theQUASES

The Pd, AuPd, and ZrO2nanoparticle–decorated functionalised multiwalled carbon nanotubes (f‐MWCNTs) were reported as efficient catalysts of formic acid (FA) electro‐oxidation. Different preparation conditions influence their chemical and structural properties analysed by X‐ray photoelectron spectroscopy aided with the quantitative analysis of surfaces by electron spectroscopy. Different reduction procedures such as NaBH4, a polyol microwave‐assisted method (PMWA), and a high pressure microwave reactor (HPMWR) were applied for decorating ZrO2/f‐MWCNTs with Pd and AuPd nanoparticles. The ZrO2nanoparticles are attached through oxygen groups to the surface of f‐MWCNTs. In NaBH4and HPMWR procedures, Pd nanoparticles precipitate predominantly on ZrO2of nearly nominal stoichiometry, whereas in PMWA procedure, Pd and AuPd nanoparticles precipitate predominantly on the surface of f‐MWCNTs, bridging with oxygen groups and ZrOx(x &lt; 2) and leading to Pd‐O‐Zr phase formation. Strong reducing procedures (NaBH4and FA) led to smaller Pd nanoparticle size, Pd oxide content, and PdOxoverlayer thickness in contrary to weak reduction procedures (HPMWR and PMWA). The highest content of Pd‐O‐Zr phase appeared for Pd predominant precipitation on ZrO2nanoparticles (HPMWR) in contrary to Pd and AuPd predominant precipitation on surface of f‐MWCNTs (NaBH4 ~ FA &gt; PMWA). Larger content of Pd‐O‐Zr phase in AuPd‐decorated ZrO2/f‐MWCNTs in contrary to Pd‐decorated sample (PMWA) could be justified by different electronic properties of nanoparticles. The FA treatment of Pd and AuPd‐ZrO2/f‐MWCNTs samples provided decreasing Pd oxide content, overlayer thickness, nanoparticle size, increasing nanoparticle surface coverage and density, amount of Pd‐O‐Zr, what results from reduction of oxygen groups bridging with Pd and ZrOxnanoparticles, also through Pd‐O‐Zr phase.

The Effects of Silica Nanoparticles on Apoptosis and Autophagy of Glioblastoma Cell Lines.

Silica nanoparticles (SiNPs) are one of the most commonly used nanomaterials in various medical applications. However, possible mechanisms of the toxicity caused by SiNPs remain unclear. The study presented here provides novel information on molecular and cellular effects of SiNPs in glioblastoma LBC3 and LN-18 cells. It has been demonstrated that SiNPs of 7 nm, 5–15 nm and 10–20 nm induce time- and dose-dependent cytotoxicity in LBC3 and LN-18 cell lines. In contrast to glioblastoma cells, we observed only weak reduction in viability of normal skin fibroblasts treated with SiNPs. Furthermore, in LBC3 cells treated with 5–15 nm SiNPs we noticed induction of apoptosis and necrosis, while in LN-18 cells only necrosis. The 5–15 nm SiNPs were also found to cause oxidative stress, a loss in mitochondrial membrane potential, and changes in the ultrastructure of the mitochondria in LBC3 cells. Quantitative real-time PCR results showed that in LBC3 cells the mRNA levels of pro-apoptotic genes Bim, Bax, Puma, and Noxa were significantly upregulated. An increase in activity of caspase-9 in these cells was also observed. Moreover, the activation of SiNP-induced autophagy was demonstrated in LBC3 cells as shown by an increase in LC3-II/LC3-I ratio, the upregulation of Atg5 gene and an increase in AVOs-positive cells. In conclusion, this research provides novel information concerning molecular mechanisms of apoptosis and autophagy in LBC3 cells.

Enriching Silver Nanocrystals with a Second Noble Metal

Noble-metal nanocrystals have received considerable interests owing to their fascinating properties and promising applications in areas including plasmonics, catalysis, sensing, imaging, and medicine. As demonstrated by ample examples, the performance of nanocrystals in these and related applications can be augmented by switching from monometallic to bimetallic systems. The inclusion of a second metal can enhance the properties and greatly expand the application landscape by bringing in new capabilities. Seeded growth offers a powerful route to bimetallic nanocrystals. This approach is built upon the concept that preformed nanocrystals with uniform, well-controlled size, shape, and structure can serve as seeds to template and direct the deposition of metal atoms. Seeded growth is, however, limited by galvanic replacement when the deposited metal is less reactive than the seed. The involvement of galvanic replacement not only makes it difficult to control the outcome of seeded growth but also causes degradation to some properties. We have successfully addressed this issue by reducing the salt precursor(s) into atoms with essentially no galvanic replacement. In the absence of self-nucleation, the atoms are preferentially deposited onto the seeds to generate bimetallic nanocrystals with controlled structures. In this Account, we use Ag nanocubes as an example to demonstrate the fabrication of Ag@M and Ag@Ag-M (M = Au, Pd, or Pt) nanocubes with a core-frame or core-shell structure by controlling the deposition of M atoms. A typical synthesis involves the titration of Mn+ (a precursor to M) ions into an aqueous suspension containing Ag nanocubes, ascorbic acid, and poly(vinylpyrrolidone) under ambient conditions. In one approach, aqueous sodium hydroxide is introduced to increase the initial pH of the reaction system. At pH = 11.9, ascorbic acid is dominated by ascorbate monoanion, a much stronger reductant, to suppress the galvanic replacement between Mn+ and Ag. In this case, the M atoms derived from the reduction by ascorbate monoanion are sequentially deposited on the edges, corners, and side faces to generate Ag@M core-frame and then core-shell nanocubes. The other approach involves the use of ascorbic acid as a relatively weak reductant while Mn+ is cotitrated with Ag+ ions in the absence of sodium hydroxide. At pH = 3.2, when the molar ratio of Ag+ to Mn+ is sufficiently high, the added Ag+ ions can effectively push the galvanic reaction backward and thus inhibit it. As a result, coreduction of the two precursors by ascorbic acid produces Ag and M atoms for the generation of Ag@Ag-M core-frame nanocubes with increasingly thicker ridges. The Ag@Ag-Pd core-frame nanocubes can serve as a dual catalyst to promote the stepwise reduction of nitroaromatics to aminoaromatics and then oxidation to azo compounds. The consecutive reactions can be monitored using surface-enhanced Raman scattering (SERS). The Ag@Au core-shell nanocubes with Au shells of three or six atomic layers exhibit plasmonic peaks almost identical to those of the Ag nanocubes while the chemical stability and SERS activity are substantially augmented. For both types of bimetallic nanocubes, the Ag cores can be selectively removed to generate nanoframes and nanoboxes.

Effect of anthropogenic aerosol emissions on precipitation in warm conveyor belts in the western North Pacific in winter – a model study with ECHAM6-HAM

Abstract. While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global climate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and amount of precipitation can be detected in North Pacific warm conveyor belts. Warm conveyor belts are the strongest precipitation-producing airstreams in extratropical cyclones and are identified here with a Lagrangian technique, i.e. by objectively identifying the most strongly ascending trajectories in North Pacific cyclones. These conveyor belts have been identified separately in 10-year ECHAM6-HAM simulations with present-day and pre-industrial aerosol conditions. Then, the evolution of aerosols and cloud properties has been analysed in detail along the identified warm conveyor belt trajectories. The results show that, under present-day conditions, some warm conveyor belt trajectories are strongly polluted (i.e. high concentrations of black carbon and sulfur dioxide) due to horizontal transport from eastern Asia to the oceanic region where warm conveyor belts start their ascent. In these polluted trajectories a weak delay and reduction of precipitation formation occurs compared to clean warm conveyor belt trajectories. However, all warm conveyor belts consist of both polluted and clean trajectories at the time they start their ascent, and the typically more abundant clean trajectories strongly reduce the aerosol impact from the polluted trajectories. The main conclusion then is that the overall amount of precipitation is comparable in pre-industrial conditions, when all warm conveyor belt trajectories are clean, and in present-day conditions, when warm conveyor belts consist of a mixture of clean and polluted trajectories.