List of Scientific Publications

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Bromine and iodine determination in human saliva: Challenges in the development of an accurate method

Date: 2019
Authors: Novo, DR;Mello, JE;Rondan, fS;Henn, AS;Mello, PA;Mesko, Mf;
References: Talanta 191 415-421
Keywords/Products: Concentric;Concentric nebulizer;ICP;ICP-MS;Meinhard;NexION;
In this work, an analytical method for bromine and iodine determination in human saliva was proposed. A simple protocol based on centrifugation and direct analysis of supernatant by inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Although this method was feasible for bromine determination, iodine was partially present in the supernatant and an agreement about 54% with reference value was obtained. In addition, microwave-induced combustion (MIC) and microwave-assisted dissolution were also evaluated. Using MIC, 0.2?mL of saliva added on 300?mg of microcrystalline cellulose were efficiently digested. A diluted solution (50?mmol?L-1 NH4OH) was used for analytes absorption, and a reflux step of 5?min was applied to ensure quantitative recoveries of Br and I. Accuracy was evaluated by analyte recovery experiments, and recoveries between 94% and 98% were obtained. Microwave-assisted dissolution was evaluated for 2.0?mL of saliva using also a diluted alkaline solution (25?mmol?L-1 NH4OH) and a microwave irradiation program of 35?min (including the cooling step). Results for this method agreed with those obtained using MIC. Although MIC has also been appropriated for further determination of Br and I in saliva, microwave-assisted dissolution can be considered a simpler sample preparation method and it was effective for high amount of sample (up to 2.0?mL). Moreover, final solutions were compatible with ICP-MS analysis, allowing the quantification of Br and I in human saliva at ultra-trace concentrations (limits of quantification were 0.052?µg?mL-1 for Br and 0.022?µg?mL-1 for I).

Monitoring and Risk Assessment of Lead and Cadmium in Various Agricultural Products Collected from the Korean Market

Date: 2018
Authors: Chang, E;Park, S;Lee, K;Choe, J;Kim, M;
References: J. fd Hyg. Safety 33 240-247
Keywords/Products: ELAN;ICP;ICP-MS;Meinhard;
This study was carried out to determine the levels of lead and cadmium as found in nine agricultural products (n = 578) sold in Korea, and to estimate the risk to human health that is summarily associated with their intake. The concentrations of Pb and Cd were measured using an ICP-MS after microwave digestion in this study. The average contents of Pb and Cd were measured as 0.014 and 0.017 mg/kg for barley, 0.006 and 0.005 mg/kg for mung bean, 0.008 and 0.007 mg/kg for kidney bean, 0.010 and 0.004 mg/kg for green bean, 0.008 and 0.001 mg/kg for pineapple, 0.016 and 0.002 mg/kg for apricot, 0.015 and 0.002 mg/kg for Japanese apricot, 0.021 and 0.002 mg/kg for plum and 0.019 and 0.003 mg/kg for jujube, respectively. The levels of Pb and Cd in the study samples were less than the maximum residual levels established by the European Union (EU), CODEX, and the Korea food Code. As we have seen, the daily dietary exposures of Pb and Cd from these agricultural products for the general population were noted as 0.067% of PTWI (25µg/kgb.w./week) and 0.28% of PTMI (25 µg/kg b.w./month), respectively. In line with the study conclusions, these results suggest that the current dietary intakes of Pb and Cd from these agricultural products in Korea have no appreciable risk effects on health for humans as noted in this experiment.

Occurrence of metals in vegetables and fruits from areas near landfill in Southern Italy and implications for human exposure

Date: 2018
Authors: Melai, V;Giovannini, A;Chiumiento, f;Bellocci, M;Migliorati, G;
References: foodContamination 5
Keywords/Products: ICP;ICP-AES;ICP-MS;Meinhard;sample introduction;
Background This paper describes the activities and the results obtained from a monitoring of contamination levels of some metals: lead (Pb), cadmium (Cd), mercury (Hg), total arsenic (Astot), vanadium (V), chromium (Cr), antimony (Sb), manganese (Mn) and aluminium (Al) in vegetable food cultivated or sold in local market, near Resit landfill in Giugliano (Campania region, Italy). This area, once well known like Campania felix for abundance and quality of food farming, supplies local, national and community markets. Unfortunately, in the last twenty years, this region has been involved in lots of illegal dumpings of hazardous and urban wastes, that have been periodically set to fire with possible health impact. for this reason it has been renamed as "Terra dei fuochi" ("Land of fires"). The aim of this study was the evaluation of the consumers exposure level to metals coming from the intake of likely contaminated vegetables and fruits. Results Vegetable and fruit samples was collected in November 2013 on fields and in february 2014 in local markets. One hundred and thirty-nine samples (peppers, eggplants, lettuces, strawberries and turnip greens) were analysed for metals: fifty-six samples from fields near Resit dump and eighty-three from local markets situated in neighboring provinces and in the southern Lazio. Metal concentrations in the investigated samples were determined by inductively coupled plasma - mass spectrometry (ICP-MS) or inductively coupled plasma - atomic emission spectrometry (ICP-AES) techniques applying validated and accredited analytical methods. Conclusions In all analysed matrices, the level of each investigated metal, highlighted a very low health risk for consumers.

Abiotic dissolution rates of 24 (nano) forms of 6 substances compared to macrophage-assisted dissolution and in vivo pulmonary clearance: Grouping by biodissolution and transformation

Date: 2018
Authors: Koltermann-Jully, J;Keller, J;Vennemann, A;Werle, K;Muller, P;Ma-Hock, L;Landsiedel, R;Wiemann, M;Wohlleben, W;
References: NanoImpact 12 29-41
Keywords/Products: ICP;ICP-MS;Meinhard;
Numerous recent reviews have highlighted the urgent need for methods to determine the biodissolution of nanomaterials in relevant lung fluids, and to validate the results against the bioprocessing in vivo. Moreover, it is largely unknown to what extent (nano)forms of a substance that differ in size, shape, or coating also differ in biodissolution. Here we apply a previously optimized abiotic flow-through method to 24 (nano)forms of 6 substances and compare the results with alveolar macrophage-assisted biodissolution of a subset of these nanomaterials in vitro and short-term inhalation results in vivo. As a main result we found that the results obtained with the flow-through method for the lung were consistent to the results of in vivo studies and were not improved by measuring alveolar macrophage-assisted biodissolution for up to 48h. Based on selected benchmark materials we propose four groups of materials according to quantitative biodissolution rates (1ng/cm2/h to 100ng/cm2/h cutoffs) and qualitative transformation parameters, as detected by TEM analysis. These groups were also reflected by different lung clearance rates, as previously determined in short term inhalation studies. Biodissolution was similar within substance (nano)forms of fe2O3, SiO2, CeO2, ZnO, though slightly varied upon surface area/coating. But the difference of biodissolution between the substances was in some cases >1000-fold. Among the Cu-containing materials, the behavior of the two CuPhthalocyanin nanoforms was similar with each other, but completely different than the dissolution and transformation of Cu salts. Different production routes and/or surface coatings significantly modulated biodissolution, whereas effects of shape or size were limited. In summary, we refined a protocol for the abiotic determination of biodissolution along with an integrated assessment of nanomaterial transformation. The protocol is suggested as tier 2 methodology for grouping and read-across purposes.

Study of the uptake and bioaccumulation of palladium nanoparticles by Sinapis alba using single particle ICP-MS

Date: 2018
Authors: Kinska, K;Jimenez-Lamana, J;Kowalska, J;Krasnodebska-Ostrega, B;Szpunar, J;
References: Science of The Total Environment 615 1078-1085
Keywords/Products: ICP;ICP-MS;Meinhard;NexION;Perkin Elmer;
In recent years, increased palladium content has been found in the environment, due to its wide use in various fields, especially as catalytic converters. Palladium can be emitted as a range of soluble and insoluble compounds and in the form of palladium nanoparticles (PdNPs). The level of toxicity is equally dependent on concentration and form of palladium and hence, it is important to determine not only the total content of this element, but also its forms of occurrence. This study for the first time investigates the uptake degree and distribution of PdNPs by model plant Sinapis alba, in comparison with a platinum salt (Pd(NO3)2). An enzymatic digestion method which allows the extraction of PdNPs from the different plant tissues without altering their properties was applied. After extraction, samples were analysed by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) to provide information about the presences of palladium in nanoparticulated or dissolved form, the nanoparticle size and the nanoparticle number concentration. Significant amounts of PdNPs were found even in aboveground organs, but no significant changes in plant morphology were observed. Size distributions of PdNPs found in all tissues presented lower diameters than size distribution of the PdNPs stock suspension, suggesting that bigger nanoparticles are not taken up by the plant. The average size found is in good agreement between the different organs. Moreover, dissolved palladium was found in all samples, with the biggest contribution, in relative terms, observed in leaves followed by stems and roots.

Differentiating Rice Varieties by Inductively Coupled Plasma Mass Spectrometry Chemical Profiling with Singular Value Decomposition Background Correction

Date: 2018
Authors: Wang, X;Harrington, P;
References: J. Anal. Test. 2 138-148
Keywords/Products: ICP;Meinhard;
As a global staple, rice has an increasing demand for differentiation and authentication, considering both fraud and health aspects for consumers. The complexity of rice urges a rapid, labor-saving, effective, and economical rice differentiation method. A semi-quantitative method using inductively coupled plasma mass spectrometry (ICP-MS) for fast and high-throughput analysis of rice entire elements with singular value decomposition (SVD) background correction (BC) was developed. The SVD BC method is the first time that it has been used with ICP-MS to minimize the effect of instrumental drift. Other data preprocessing methods, normalization (NM), error scaling (ES), and standard normal variate (SNV) were evaluated by principal component analysis (PCA) and projected difference resolution (PDR). A fuzzy rule-building expert system (fuRES), super partial least squares discriminant analysis (sPLS-DA), support vector machine (SVM), and SVM classification tree (SVMTreeG) classifiers gave 98.1±0.0, 99.8±0.4, 99.8±0.4, and 100.0±0.0% prediction rates with all of the data preprocessing methods (NM, SVD BC with one component to reconstruct the background, ES, and SNV) for the differentiation of the nine rice-digested samples, respectively.

Additive Printing of Gold Nanoparticles on Paper Substrate Through Office Ink-Jet Printer

Date: 2018
Authors: Shariq, M;Dixit, A;Kargl, R;Chattopadhyaya, S;Sridutt, M;Vardhan, P;Rudolf, R;
References: Advances in Manufacturing Engineering and Materials 220-228
Keywords/Products: Agilent;ICP;ICP-OES;Meinhard;
The article reports the synthesis of the concentrated Gold Nanoparticles (AuNPs) ink and its printing on the paper substrate through Office Ink Jet printer. Initially, AuNPs were synthesized from the precursor Gold (III) Acetate through Ultrasonic Spray Pyrolysis. Ellipsoidal shaped AuNPs with a size distribution of below 50 nm were confirmed through TEM and DLS measurement. Maximum absorbance wavelength of AuNPs measured through UV-vis spectroscopy was 532 nm. further, the AuNPs ink was prepared through the rotavapour and filtered upto the Au concentration of 600 ppm determined through ICP-OES. The AuNPs printed patterns on the photo paper substrate were successfully printed and further analyzed with SEM.


Date: 2018
Authors: Rudolf, R;Shariq, M;Veselinovic, V;Adamovic, T;
References: 106-112
Keywords/Products: Agilent;ICP;Meinhard;
This work presents a review of Ultrasonic Spray Pyrolysis (USP) as a technique for the synthesis of gold nanoparticle (AuNPs). The synthesis mechanism involved the preparation of the precursor solution from Au (III) Acetate and the study of the process parameters. AuNPs were characterized with different techniques, such as DLS, UV-vis and SEM-EDX analyses. In the second step, the AuNPs ink was prepared with the following procedure: (i) Concentration of the AuNPs through Rotavapor, (ii) filtration of the concentrated AuNPs through Amicon Ultra 15 Centrifugal filters. Then, it was used directly for printing on an Ag plate. In the final part, we present some information about AuNPs future applications, which could be in printed electronics with conducted patterns.

Propagation of sub-atmospheric methyl formate flames

Date: 2018
Authors: Lee, DJ;Burrell, RR;Egolfopoulos, FN;
References: Combustion and Flame 189 24-32
Keywords/Products: Meinhard;TR-50-A3;
Laminar flame speeds of methyl formate/air mixtures were measured at sub-atmospheric pressures for which limited data exist. The experiments were carried out in the counterflow configuration at an unburned mixture temperature of 333 K. The flow velocities were measured using particle image velocimetry. Particle phase slip correction was applied to low-pressure data sets for which the density disparity between the flow tracers and the gaseous phase is notable. The data were modeled using two recently developed kinetic models of methyl formate oxidation, and significant disagreements were realized at all pressures especially under fuel-rich conditions. Additionally, the computed species profiles of CO and CO2 in the burner-stabilized flame configuration using the two models were found to differ significantly. Reaction path analysis revealed that the kinetics of CH2OCHO that is produced directly from the fuel affects the overall reactivity, and the attendant rate constants differ between the two models. The variation of laminar flame speed with pressure revealed also a different behavior between experiments and simulations. Further insight into the sources causing the observed discrepancies were investigated and it was determined that reactions involving formyl radical, methanol, and formaldehyde could also be responsible for the reduction in reactivity specifically under fuel-rich conditions.

Analysis of Cerium Dioxide Nanoparticles in Soil Using Single Particle ICP-MS

Date: 2018
Authors: Liu, W;Shi, H;Stephan, C;Monitoring, SM;
References: Product 1 1-52
Keywords/Products: ICP;ICP-MS;Meinhard;NexION;Type C;
Over the past few decades, engineered nanoparticles (ENPs) have been increasingly used in many commercial products. 1,2 As a result, more and more ENPs have been released into the environment, which raises concerns over their fate, toxicity and transport therein. 3 Cerium dioxide nanoparticles (CeO2 NPs) are widely used in industry, and once they are released into the environment, soils are likely to be their primary repository. Nevertheless, given their relatively low concentrations and high natural background of Ce-containing minerals in the environment, it still remains a challenge to detect and characterize the CeO2 NPs in environmental samples. Single particle ICP-MS (SP-ICP-MS) has proven to be a powerful technique to detect and characterize ENPs, especially at very low concentrations (as expected in environmental samples), owing to its capability to quickly provide information about particle size, size distribution and particle number concentration. 4-6 Since its development, SP-ICP-MS has been successfully utilized to investigate ENPs in various matrices. 7-16 This work demonstrates a robust method using SP-ICP-MS technology to detect CeO2 NPs which were extracted from soil samples with tetrasodium pyrophosphate (TSPP).

Development of a multi-collector inductively coupled plasma massspectrometry method for measurement of stable sulphur isotope ratios in aerosol sulphate

Date: 2018
Authors: Rodiouchkina, K;
References: Thesis 1 1-52
Keywords/Products: Aerosol;Aridus;ICP;ICP-MS;Meinhard;Neptune;Thermo;
Sulphur stable isotope ratios are useful tracers in geological and environmental studies. They can for example be used to trace the origin of atmospheric sulphate aerosols, because anthropogenic sulphate and natural sulphate have distinguishable δ34S-values (δ34S value of approximately +0 to +8 ‰ for anthropogenic and approximately +12 to +19 ‰ for natural). This is useful for climate modelling research, due to the net cooling effect of aerosol sulphate. In the present study a Nu Plasma II (Nu Instruments) multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) method for measuring stable sulphur isotope ratios in low sulphur content samples, such as sulphate aerosols, was developed. The method was then applied to a sulphate aerosol sample collected in the Maldives.Most of the measurements were performed at high resolution, due to the interferences on 33S. Heated spray chamber coupled to a desolvating membrane, Aridus II (Cetac), increased the sensitivity and reduced interferences notably compared to wet plasma mode. Aridus II gave more stable measurements than DSN-100 (Nu Instruments). Determinations of δ34S for IAEA S1, S3, and S4 were accurate and the determined δ34S-value of the CIT #39 seawater standard (21.05 ± 0.36 ‰, 2SD, n=42) was comparable with published data. In general, Si internal standardization correction increased precision ~2.5 times compared to non-corrected values. The δ34S-value for the sulphate aerosol sample was determined to 3.82 ±0.41 ‰ (2SD, n=40). Repeatability of ~62 nmol introduced sulphur (2 µg/mL) was generally 0.15 ‰ (2SD, n=5) for the SW and 0.19 ‰ (2SD, n=5) for the sulphate aerosol sample. Comparable results for the SW (20.61±0.09 ‰, 2SD, n=4) and sulphate aersosol sample (3.77 ± 0.08 ‰, 2SD, n=8) were obtained with the method applied to Neptune Plus (Thermo fischer Scientific) MC-ICP-MS in a different laboratory. The determined aerosol sulphate δ34S-value indicated that the sampled sulphate aerosol originated from anthropogenic sources.

Quantification of Gold Nanoparticle Uptake into Cancer Cells using Single Cell ICP-MS

Date: 2018
Authors: Wilhelm, S;Bensen, RC;Kothapalli, NR;Burgett, AWG;
References: Product 1 1-4
Keywords/Products: HEN;High Efficiency Nebulizer;ICP;ICP-MS;Meinhard;
Cancer is a disease that is characterized by the uncontrolled growth and spread of abnormal cells. According to the American Cancer Society, cancer is the second most common cause of death in the US. 1 Current treatments for various cancers include surgery, radiation, immunotherapy, and chemotherapy. Although these conventional therapies may improve patients' overall survival and quality of life, they also have several limitations. for example, in conventional cancer chemotherapy, small-molecule-based cancer therapeutics distribute non-specifically throughout the entire human body. The consequence is that these drugs do not only kill cancer cells but also destroy healthy cells in the body causing severe side effects for cancer patients, 2 leading to a need for new therapies that can target diseased cells. Nanoparticles (NPs) have been of significant interest over the last two decades as they offer attractive benefits for drug delivery to overcome limitations in conventional chemotherapy. 3 Nanoparticles can be engineered to carry both drugs and imaging probes to simultaneously detect and treat cancer. They may also be designed to specifically target diseased tissues and cells in the body. A number of nanoparticlebased cancer therapeutics have been approved for clinical use and/or are currently under development. 4,5 Advantages that rationally engineered nanoparticles may offer over conventional small-molecule drugs include: (i) prolonged circulation time in the body; (ii) reduction of nonspecific cellular uptake and undesirable off-target and side effects; and (iii) improvement in cellular interactions through specific cancer cell targeting moieties.

(Metodologie analitiche per la determinazione di contaminanti da materiali a contatto con gli alimenti) Analytical methods for the determination of contaminants from materials in contact with food

Date: 2018
Authors: Zoani, C;Pucci, E;Zappa, G;
References: Thesis 1 1-53
Keywords/Products: Meinhard;
This work reports about an experimental study aimed to characterize a film of PolyLactic Acid functionalised with silver (Ag-PLA) for use as packaging, performing some comparisons with a PolyLactic Acid film as it is (PLA-TQ). In order to determine total content of Ag on PLA functionalised with Ag (Ag-PLA), make preliminary evaluations on the presence of element potentially migrant (considering those elements for which the EU Regulation establishes Specific Migration Limits - SML: Ba, Co, Cu, fe, Li, Mn and Zn) on PLA-TQ and Ag-PLS, and to evaluate eventual differences between the elemental contacts in the pellets used as raw material, in both PLA-TQ and PLA-Ag, a analytical methods to determine the total elemental content by ICP-AES has been set up. The method foresees a pre-treatment procedure of sample total dissolution by a high-pressure microwave digestion system. The methodologies to perform the overall and specific migration tests have been set up with different food simulants, at different temperatures and with different contact times, according to Reg. (UE) n 10/2011 (consolidated version 2014). Overall Migration (OM) has been evaluated gravimetrically, while Specific Migration (SM) of Ag in the simulant solutions collected at the different conditions (different t and T) has been determined by ICP-MS. furthermore, dry residue obtained from the different solutions collected at the different conditions (different t and T) has been determined gravimetrically. for a wider evaluation and a better interpretation of the effects induced by food simulants at the different exposure conditions (t and T), PLA and Ag-PLA films have been submitted to thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). In order to more widely characterize the material and evaluate the antibacterial effectiveness of Ag-PLA, microbiological tests have been performed using E. Coli C2984 in Luria-Bertani (LB) medium and LB broth. Static growth has been evaluated and the conditions for the dynamic growth have been established. finally, with the aim to study in detail the eventual release of Ag nanoparticles from Ag-PLA, a methodology based on flow field fractionation (fff) is under set up for detecting and characterizing nanoparticles in the extraxìcts obtained from migration tests.

Growth, structure and characterization of physico-chemical and magnetic properties of CdCr2Se4: Mn single crystals

Date: 2018
Authors: Jendrzejewska, I;Gron, T;Kusz, J;Goraus, J;Kita, A;Barsova, Z;Slebarski, A;Fijalkowski, M;Pietrasik, E;Zajdel, P;Duda, H;
References: Journal of Alloys and Compounds 735 480-488
Keywords/Products: Concentric;Meinhard;
Crystal structure, magnetic and specific heat measurements, electrical conductivity, as well as DSC/TG measurements for single-crystalline CdxMnyCrzSe4 (where x + y + z ≈ 3) spinels are presented. The electrical conductivity and dc magnetic susceptibility measurements exhibit thermally activated semiconducting properties and ferromagnetic (FM) order for all compositions below the Curie temperature TC = 130 K, respectively. The long-range FM interactions, defined by the Curie temperature, do not substantially depend on the manganese content, and the nearest neighbour FM interactions, represented by the positive value of the Curie-Weiss temperature, decrease from 183 K to 156 K. Hysteresis loops of all crystals have a very small coercive field (˜18 Oe) and remanence (˜0.09 µB/f.u.) with full saturation above 10 kOe. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including spin defects.

Ion-pairing reversed-phase chromatography coupled to inductively coupled plasma mass spectrometry as a tool to determine mercurial species in freshwater fish

Date: 2018
Authors: Cheng, H;Chen, X;Shen, L;Wang, Y;Xu, Z;Liu, J;
References: J Chromatogr A 1531 104-111
Keywords/Products: Concentric;Concentric nebulizer;ICP;ICP-MS;Meinhard;Thermo;TR-30-A1;
Most of analytical community is focused on reversed phase high performance liquid chromatography (RP-HPLC) for mercury speciation by employing mobile phases comprising of high salts and moderate amounts of organic solvents. This study aims at rapid mercury speciation analysis by ion-pairing RP-HPLC with inductively coupled plasma mass spectrometry (ICP-MS) detection only using low salts for the sake of green analytical chemistry. Two ion-pairing HPLC methods were developed on individual usage of positively and negatively charged ion-pairing reagents (tetrabutylammonium hydroxide -TBAH and sodium dodecylbenzene sulfonate -SDBS), where sodium 3-mercapto-1-propysulfonate (MPS) and l-cysteine (Cys) were individually added in mobile phases to transform mercury species into negative and positive Hg-complexes for good resolution. Addition of phenylalanine was also utilized for rapid baseline separation in combination of short C18 guard columns. Optimum mobile phases of 2.0mM SDBS+2.0mM Cys+1.0mM Phe (pH 3.0) and 4.0mM TBAH+2.0mM MPS+2.0mM Phe (pH 6.0) both achieved baseline separation of inorganic mercury (Hg2+), methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) on two consecutive 12.5-mm C18 columns. The former mobile phase was selected for mercury speciation in freshwater fish because of short separation time (3.0min). Detection limits of 0.015 for Hg2+, 0.014 for MeHg, 0.028 for EtHg and 0.042 gL-1 for PhHg were obtained along with satisfactory precisions of peak height and area (1.0-2.8% for 5.0 gL-1 Hg-mixture standard). Good accordance of determined values of MeHg and total mercury in certified reference materials of fish tissue (GBW 10029) and tuna fish (BCR-463) with certified values as well as good recoveries (91-106%) proved good accuracy of the proposed method. An example application to freshwater fish indicated its potential in routine analysis, where MeHg was presented at 3.7-20.3 gkg-1 as the dominate species.

Benchmarking high surface area electrocatalysts in a gas diffusion electrode: measurement of oxygen reduction activities under realistic conditions

Date: 2018
Authors: Inaba, M;Jensen, A;Sievers, G;Escudero-Escribano, M;Zana, A;Arenz, M;
References: Energy Environ. Sci. 11 988-994
Keywords/Products: Meinhard;TR-30-K1;
In this work, we introduce the application of gas diffusion electrodes (GDE) for benchmarking the electrocatalytic performance of high surface area fuel cell catalysts.

Evolving affinity between Coulombic reversibility and hysteretic phase transformations in nano-structured silicon-based lithium-ion batteries

Date: 2018
Authors: Ogata, K;Jeon, S;Ko, DS;Jung, IS;Kim, JH;Ito, K;Kubo, Y;Takei, K;Saito, S;Cho, YH;Park, H;Jang, J;Kim, HG;Kim, JH;Kim, YS;Choi, W;Koh, M;Uosaki, K;Doo, SG;Hwang, Y;Han, S;
References: Nat Commun 9 479
Keywords/Products: Meinhard;
Nano-structured silicon is an attractive alternative anode material to conventional graphite in lithium-ion batteries. However, the anode designs with higher silicon concentrations remain to be commercialized despite recent remarkable progress. One of the most critical issues is the fundamental understanding of the lithium-silicon Coulombic efficiency. Particularly, this is the key to resolve subtle yet accumulatively significant alterations of Coulombic efficiency by various paths of lithium-silicon processes over cycles. Here, we provide quantitative and qualitative insight into how the irreversible behaviors are altered by the processes under amorphous volume changes and hysteretic amorphous-crystalline phase transformations. Repeated latter transformations over cycles, typically featured as a degradation factor, can govern the reversibility behaviors, improving the irreversibility and eventually minimizing cumulative irreversible lithium consumption. This is clearly different from repeated amorphous volume changes with different lithiation depths. The mechanism behind the correlations is elucidated by electrochemical and structural probing.

From a Au-rich core/PtNi-rich shell to a Ni-rich core/PtAu-rich shell: an effective thermochemical pathway to nanoengineering catalysts for fuel cells

Date: 2018
Authors: Lu, A;Wu, Z;Chen, B;Peng, D;Yan, S;Shan, S;Skeete, Z;Chang, F;Chen, Y;Zheng, H;Zeng, D;Yang, L;Sharma, A;Luo, J;Wang, L;Petkov, V;Zhong, C;
References: J. Mater. Chem. A 6 5143-5155
Keywords/Products: ICP;ICP-OES;Meinhard;
A major challenge for the design of noble metal nanocatalysts is the ability of surface engineering to enhance the activity and stability with minimum use of the noble metals.

The impacts of phosphorus deficiency on the photosynthetic electron transport chain

Date: 2018
Authors: Carstensen, A;Herdean, A;Schmidt, SB;Sharma, A;Spetea, C;Pribil, M;Husted, S;
References: Plant Physiol.
Keywords/Products: Agilent;ICP;ICP-OES;Meinhard;
Phosphorus (P) is an essential macronutrient, and P deficiency limits plant productivity. Recent work showed that P deficiency affects electron transport to photosystem I (PSI), but the underlying mechanisms are unknown. Here, we present a comprehensive biological model describing how P deficiency disrupts the photosynthetic machinery and the electron transport chain through a series of sequential events in barley (Hordeum vulgare). Phosphorus deficiency reduces the orthophosphate (Pi) concentration in the chloroplast stroma to levels that inhibit ATP synthase activity. Consequently, protons accumulate in the thylakoids and cause lumen acidification, which inhibits linear electron flow. Limited plastoquinol (PQH2) oxidation retards electron transport to the cytochrome (Cyt) b6f complex, yet the electron transfer rate of PSI is increased under steady-state growth light and is limited under high light conditions. Under P deficiency, the enhanced electron flow through PSI increases the levels of NADPH, whereas ATP production remains restricted and hence reduces CO2 fixation. In parallel, lumen acidification activates the qE component of the non-photochemical quenching (NPQ) mechanism and prevents over-excitation of photosystem II (PSII) and damage to the leaf tissue. Consequently, plants can be severely affected by P deficiency for weeks without displaying any visual leaf symptoms. All of the processes in the photosynthetic machinery influenced by P deficiency appear to be fully reversible and can be restored in less than 60 min after resupply of Pi to the leaf tissue.

Gold core-labeled TiO2 nanoparticles for tracking behavior in complex matrices: synthesis, characterization, and demonstration

Date: 2018
Authors: Deline, A;Young, W;Nason, J;
References: Environ. Sci.: Nano 5 956-968
Keywords/Products: ICP;ICP-MS;Meinhard;NexION;Perkin Elmer;Type C;
Titanium dioxide nanoparticles (TiO2 NPs) are increasingly entering natural systems due to their widespread production and use. It is critical that TiO2 NP behavior is studied in real-world systems, but experimental work is complicated by the high levels of background titanium present in every environmental compartment. To assist in distinguishing between engineered NPs and background titanium, labeled particles with gold nanoparticle cores and TiO2 shells (Au@TiO2 NPs) were developed and the properties and behavior compared to unlabeled TiO2 NPs. Both particle types had primary particle diameters of approximately 200 nm and were stable in solutions at ionic strengths up to 500 mM due to a polyvinylpyrrolidone surface coating. To demonstrate utility, the Au@TiO2 NPs were used in several spike-and-recovery experiments in complex matrices such as activated sludge and a river water-sunscreen mixture. Au@TiO2 NPs were accurately quantified at using instrumental neutron activation analysis and inductively coupled plasma optical emission spectrometry.

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