Study of the composition and size distribution of gold-containing bimetallic nanoparticles synthesized in a spark discharge generator

Nanotechnology is one of the most dynamically growing fields of science, which requires the production of engineered nanoparticles (ENP) for various applications. Chemical synthesis procedures were dominating the field for many years, but physical procedures, that are based on laser or discharge ablation, are becoming more and more popular nowadays. One of these ablation-based methods is spark discharge generation, which is a versatile method for the preparation of mono- or bimetallic nanoparticles. In a spark discharge generator (SDG), a high voltage oscillating discharge is produced between two electrodes made of at least moderately conducting material. The erosion of the electrodes produce an atomic vapor in the spark gap, which is carried away by a gas flow. Nucleation and coagulation processes lead to nano-sized aggregates, which are then compacted to form spherical nanoparticles (NP). This method produces high purity NPs. SDGs can also be run continuously, thus industrial rate production is also possible. Control of the particle properties (e.g. concentration and size) can be achieved by tuning the operating conditions of the generator. The SDG method can also be considered cost-efficient and environmentally friendly. The goal of the present work was to study how the operating parameters of SDGs influence the composition and size distribution NPs in the case of certain bimetallic particles (BNPs). In particular, we intended to study the influence of the electrode polarity, gap size and compaction on Au-Ag and Au-W particles

Assessment of the usefulness of libs and ICP-MS for the characterization of nanoparticles in industrial and environmental samples

The need for analytical techniques capable for the detection and characterization of nanoparticles (NPs) in industrial and environmental matrices also grows along with the quickly expanding use of NPs in various products. Two candidate analytical techniques are laser induced breakdown spectroscopy (LIBS) and inductively coupled plasma mass spectrometry (ICP-MS). Both of these sensitive and versatile techniques provide elemental compositional information. Based on the success of the application of LIBS in aerosol analysis this technique can be expected to be similarly useful in NP monitoring applications, such as the detection of NPs in liquid or gaseous matrices, or for the monitoring of the properties of NPs produced by physical generation methods (e.g. electrical discharges or laser ablation). ICP-MS on the other hand has already proven itself useful in the literature, both in the solution or single particle analysis (spICP-MS) modes, for the characterization of nanoparticles. In recent years we also reported about the successful development of several ICP-MS based analytical methods for the compositional and dimensional analysis of NPs (e.g. [1, 2]). In our study we assessed the potential of LIBS and ICP-MS for nanoparticle detection and characterization both in on-line (only for LIBS) or off-line (following collection on a filter) mode. Dispersions of various types of nanoparticles (e.g. monometallic, bimetallic, oxide) in simulated or real liquid and gaseous industrial and environmental matrices were measured. Some NPs were obtained commercially, while others were generated by inlaboratory developed electrical (spark or arc) discharge generators. Additional and reference characterization of the nanoparticles were performed by electron microscopy (SEM, TEM) and scanning mobility particle sizer (SMPS). Size and mass detection limits were also calculated for on-line LIBS detection of nanoaerosols and for spICP-MS detection of NPs in aqueous nanodispersions

Impaired working speed and executive functions as frontal lobe dysfunctions in young first-degree relatives of schizophrenic patients

The aim of the investigation was to detect neuropsychological markers, such as sustained and selective attention and executive functions, which contribute to the vulnerability to schizophrenia especially in young persons. Performance was assessed in 32 siblings and children of schizophrenic patients and 32 matched controls using Wisconsin Card Sorting Test, Colour-Word-Interference-Test, Trail Making Test, and d2-Concentration-Test. The first-degree relatives showed certain impairments on all four tests, in particular, slower times on all time-limited tests. These results suggest the need for more time when completing neuropsychological tasks involving selected and focused attention, as well as cognitive flexibility, as a possible indicator of genetic vulnerability to schizophrenia

Analysis of pairwise comparison matrices: an empirical research

Pairwise comparison (PC) matrices are used in multi-attribute decision problems (MADM) in order to express the preferences of the decision maker. Our research focused on testing various characteristics of PC matrices. In a controlled experiment with university students (N = 227) we have obtained 454 PC matrices. The cases have been divided into 18 subgroups according to the key factors to be analyzed. Our team conducted experiments with matrices of different size given from different types of MADM problems. Additionally, the matrix elements have been obtained by different questioning procedures differing in the order of the questions. Results are organized to answer five research questions. Three of them are directly connected to the inconsistency of a PC matrix. Various types of inconsistency indices have been applied. We have found that the type of the problem and the size of the matrix had impact on the inconsistency of the PC matrix. However, we have not found any impact of the questioning order. Incomplete PC matrices played an important role in our research. The decision makers behavioral consistency was as well analyzed in case of incomplete matrices using indicators measuring the deviation from the final order of alternatives and from the final score vector

Metformin Attenuates Palmitate-Induced Endoplasmic Reticulum Stress, Serine Phosphorylation of IRS-1 and Apoptosis in Rat Insulinoma Cells

Lipotoxicity refers to cellular dysfunctions caused by elevated free fatty acid levels playing a central role in the development and progression of obesity related diseases. Saturated fatty acids cause insulin resistance and reduce insulin production in the pancreatic islets, thereby generating a vicious cycle, which potentially culminates in type 2 diabetes. The underlying endoplasmic reticulum (ER) stress response can lead to even β-cell death (lipoapoptosis). Since improvement of β-cell viability is a promising anti-diabetic strategy, the protective effect of metformin, a known insulin sensitizer was studied in rat insulinoma cells. Assessment of palmitate-induced lipoapoptosis by fluorescent microscopy and by detection of caspase-3 showed a significant decrease in metformin treated cells. Attenuation of β-cell lipotoxicity was also revealed by lower induction/activation of various ER stress markers, e.g. phosphorylation of eukaryotic initiation factor 2α (eIF2α), c-Jun N-terminal kinase (JNK), insulin receptor substrate-1 (IRS-1) and induction of CCAAT/enhancer binding protein homologous protein (CHOP). Our results indicate that the β-cell protective activity of metformin in lipotoxicity can be at least partly attributed to suppression of ER stress

U-Shaped Relation between Plasma Oxytocin Levels and Behavior in the Trust Game

10.1371/journal.pone.0051095PLoS ONE712

The Shine-Through Masking Paradigm Is a Potential Endophenotype of Schizophrenia

BACKGROUND: To understand the genetics of schizophrenia, a hunt for so-called intermediate phenotypes or endophenotypes is ongoing. Visual masking has been proposed to be such an endophenotype. However, no systematic study has been conducted yet to prove this claim. Here, we present the first study showing that masking meets the most important criteria for an endophenotype. METHODOLOGY/PRINCIPAL FINDINGS: We tested 62 schizophrenic patients, 39 non-affected first-degree relatives, and 38 healthy controls in the shine-through masking paradigm and, in addition, in the Continuous Performance Test (CPT) and the Wisconsin Card Sorting Test (WCST). Most importantly, masking performance of relatives was significantly in between the one of patients and controls in the shine-through paradigm. Moreover, deficits were stable throughout one year. Using receiver operating characteristics (ROC) methods, we show that the shine-through paradigm distinguishes with high sensitivity and specificity between schizophrenic patients, first-order relatives and healthy controls. CONCLUSIONS/SIGNIFICANCE: The shine-through paradigm is a potential endophenotype

Electrophysiological correlates of reinforcement learning in young people with Tourette syndrome with and without co-occurring ADHD symptoms

Altered reinforcement learning is implicated in the causes of Tourette syndrome (TS) and attention-deficit/hyperactivity disorder (ADHD). TS and ADHD frequently co-occur but how this affects reinforcement learning has not been investigated. We examined the ability of young people with TS (n = 18), TS+ADHD (N = 17), ADHD (n = 13) and typically developing controls (n = 20) to learn and reverse stimulus-response (S-R) associations based on positive and negative reinforcement feedback. We used a 2 (TS-yes, TS-no) x 2 (ADHD-yes, ADHD-no) factorial design to assess the effects of TS, ADHD, and their interaction on behavioural (accuracy, RT) and event-related potential (stimulus-locked P3, feedback-locked P2, feedback-related negativity, FRN) indices of learning and reversing the S-R associations. TS was associated with intact learning and reversal performance and largely typical ERP amplitudes. ADHD was associated with lower accuracy during S-R learning and impaired reversal learning (significantly reduced accuracy and a trend for smaller P3 amplitude). The results indicate that co-occurring ADHD symptoms impair reversal learning in TS+ADHD. The implications of these findings for behavioural tic therapies are discussed