Modification of Surface Bond Au Nanospheres by Chemically and Plasmonically Induced Pd Deposition

In this work we investigated methods of modifying gold nanospheres bound to a silicon surface by depositing palladium onto the surfaces of single nanoparticles. Bimetallic Au-Pd nanoparticles can thus be gained for use in catalysis or sensor technology. For Pd deposition, two methods were chosen. The first method was the reduction of palladium acetate by ascorbic acid, in which the amounts of palladium acetate and ascorbic acid were varied. In the second method we utilized light-induced metal deposition by making use of the plasmonic effect. Through this method, the surface bond nanoparticles were irradiated with light of wavelengths capable of inducing plasmon resonance. The generation of hot electrons on the particle surface then reduced the palladium acetate in the vicinity of the gold nanoparticle, resulting in palladium-covered gold nanospheres. In our studies we demonstrated the effect of both enhancement methods by monitoring the particle heights over enhancement time by atomic force microscopy (AFM), and investigated the influence of ascorbic acid/Pd acetate concentration as well as the impact of the irradiated wavelengths on the enhancement effect. It could thus be proven that both methods were valid for obtaining a deposition of Pd on the surface of the gold nanoparticles. Deposition of Pd on the gold particles using the light-assisted method could be observed, indicating the impact of the plasmonic effect and hot electron for Pd acetate reduction on the gold particle surface. In the case of the reduction method with ascorbic acid, in addition to Pd deposition on the gold nanoparticle surface, larger pure Pd particles and extended clusters were also generated. The reduction with ascorbic acid however led to a considerably thicker Pd layer of up to 54 nm in comparison to up to 11 nm for the light-induced metal deposition with light resonant to the particle absorption wavelength. Likewise, it could be demonstrated that light of non-resonant wavelengths was not capable of initiating Pd deposition, since a growth of only 1.6 nm (maximum) was observed for the Pd layer.

Platelet Desialylation As a Predictive Marker in Childhood Immune Thrombocytopenia (ITP)

Background and aim: Immune thrombocytopenia (ITP) is the most common bleeding condition in children. Its prognosis is mostly superior, however, severe refractory disease remains diagnostic and therapeutic challenge. Low platelet counts (<100× 109/L) are associated with increased platelet clearance by two parallel mechanisms: classical antibody-mediated pathway and a novel lectin-carbohydrate mediated pathway. The latter is based on platelet desialylation, where terminal sialic acids are cleaved from glycoconjugates, mainly glycoproteins (GPs), on the platelet surface. The loss of sialic acid enhances bond of the penultimate β-galactose to asialoglycoprotein receptors (ASGPRs, also called Ashwell-Morell receptors) on hepatocytes. Desialylated platelets are then captured and phagocytosed by ASGPR-expressing hepatocytes. Desialylation has been shown to be responsible for platelet destruction in many contexts, e.g., infection-related thrombocytopenia or clearance of senescent platelets. Loss of T-cell tolerance is another underlying mechanism in ITP; CD8+ regulatory T cells (Tregs) are able to inhibit overactive immune response and maintain immune homeostasis. Forkhead box P3 (FOXP3) and GATA3 are transcription factors crucial for development and proper function of Tregs limiting the Th2-type inflammatory response. Our aims were to distinguish contribution of the mentioned processes to ITP development and to characterize immune response in children with ITP during the course of disease (diagnosis, ongoing therapy, remission, refractory/persistent ITP). Patients and Methods: We examined 30 samples from 20 children with ITP (12 males, 8 females, age 3-17 years; 3 acute ITP, 17 chronic ITP) and 10 healthy controls (age 4-15). The degree of desialylation was determined by flow cytometry using FITC-labeled Ricinus communis agglutinin (RCA-I) specific for terminal galactose or N-acetylgalactosamine. Expression of platelet surface markers was given quantitatively as mean fluorescence intensity (MFI). Presence of platelet surface-bond antibodies (IgG, IgA and IgM) was examined by flow cytometry. Subpopulations of CD4+ and CD8+ T-cells were characterized based on intracellular expression of transcription factors T-bet (Th1 cells), GATA3 (Th2 cells), ROR gamma T (Th17 cells) and FOXP3 (for Tregs) using multicolor flow cytometry. Results: Patients with ITP showed significant increase in RCA-I reactivity in comparison with healthy controls (p<0.001). Patients with newly diagnosed ITP showed the most aberrant sialylation (i.e., maximum desialylation) of platelet surface proteins. A decrease in desialylation intensity was noticeable as soon as at three days after therapy initiation. Sialylation levels returned to normal after one month of successful treatment and were similar to healthy controls in children with ITP remission. Platelet surface-bond immunoglobulins were increased in 10 (50%) patients independently on their sialylation level. We observed significant changes in T-cell subpopulations in ITP: T lymphocytes producing T-bet were decreased within both CD4+ and CD8+ populations. Percentage of CD4+ cells expressing ROR gamma T was also reduced. Proportions of cells expressing FOXP3 and GATA3 were decreased within the CD8+ but not within the CD4+ population. Conclusion: Our results highlight the importance of Fc-independent hepatic platelet clearance in ITP. Interindividual differences in ITP pathophysiology are reflected by treatment response and may improve therapeutic management and prognostication. E.g., intravenous immunoglobulins or splenectomy will be ineffective in patients with prevalent Fc-independent mechanisms, and contrarily, possibilities for novel targeted treatment (neuraminidase inhibitors) arise. Better understanding of immune-mediated processes involved in ITP pathogenesis may reduce adverse effects of immunosuppressive therapy and considerably improve quality of life in patients with ITP. Supported by: MH CZ - DRO (FNOl, 00098892), Project ENOCH (No. CZ.02.1.01/0.0/0.0/16_019/0000868) and Ministry of Education, Youth and Sports OPVVV CEREBIT CZ.02.1.01/0.0/0.0/16_025/0007397. Disclosures No relevant conflicts of interest to declare.

Effect of Sand Coating with Solution on Bond Strength of Bamboo

In a developing country like India, there is an increasing demand for RCC. The major component of RCC is steel. Steel is an alloy of carbon. In manufacturing processes of steel lots of energy is required. For such energy, lots of natural energy sources are used which can adversely affect the environment. For sustainable development, Bamboo may be a proper replacement for steel. Bamboo is fast growing grass which easily cultivated in any types of land. For replacement of bamboo, the bond between bamboo and concrete must be strong. The bond strength of bamboo and concrete is a major concern in the use of bamboo. The surface of the bamboo is naturally coated and has a smooth surface. Due to smooth surface bond strength is decreasing. For increasing bond strength there must be the proper coating for bamboo. In this paper, a solution is used for coating. For roughness, the surface is coated with sand with a solution. For comparing bond strength of different coated surface pull out the test is carried out. For pull out, test samples with the various coated surfaces are cast and tested after 7, 14 and 28 days. The result shows an increase in bond strength of the coated surface.

A Review of Direct Shear Testing Configurations for Bond between Fiber-Reinforced Polymer Sheets on Concrete and Masonry Substrates

The surface bond characteristics of Fiber-Reinforced Polymer (FRP) sheets have been subject to research for more than two decades. These sheets generally exhibit brittle performance during direct shear and often delaminate prematurely before they attain the full strength of the material. This paper reviews the experimental testing configurations to investigate the direct shear bond surface characteristics of FRP sheets on concrete and masonry substrates. Additionally, it summarizes the data acquisition methods and the observed behavior for surface bond of FRP sheets on concrete and masonry. This review aims to serve as a source for future experimental research studies in the field. Further, an innovative testing configuration is suggested to measure bond strength of FRP sheets on concrete and masonry surfaces in direct shear.