The evolution of Pd/Sn catalytic surfaces in electroless copper deposition

This paper describes the different catalytic surfaces of Pd/Sn formed before electroless copper deposition onto a glass substrate. In this study, silanization of the glass surfaces with (3-aminopropyl) trimethoxysilane was used to provide a surface-coupled layer of functional molecules to assist in the adsorption of Pd/Sn catalyst and the subsequent copper deposition. The composition and microstructure of the modified glass surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry. These showed that catalytic Pd/Sn structures on the surface changed with increasing immersion time in the catalyst bath. The core-level XPS spectrum of Pd indicated that metallic Pd(0) became more significant in the catalyst layer than Pd(II) with the increasing immersion time. A model of the adsorption process is proposed to explain these changes. It was observed that too high a quantity of Pd(0) does not always improve the adhesion of the Cu deposits in the electroless process

Alkali incorporation into solution processed CIGS precursor layers

Solution based ion-exchange reactions offer a simple, non-vacuum route for adding Cu into In- Ga-Se precursor layers as a step in a low-cost process for the preparation of Cu(In, Ga)Se2 (CIGS) solar cells. The chemically treated precursor layers may be converted into CIGS by annealing with Se vapour. Structural and compositional characterisation has shown that the converted layers have good composition, microstructure and crystalline phase content. Nevertheless, photovoltaic cells processed from these layers have failed to produce energy conversion efficiencies greater than ~4% under standard test conditions. The chemical bath used for the incorporation of Cu into the precursor layers includes a complexant for stability and this complexant contains alkali atoms, which are known to strongly influence the properties of CIGS. Low alkali content is highly desirable in CIGS layers but excessive inclusion may be detrimental. This paper reports the results of an investigation into the potential incorporation of excess alkali atoms from the solution into the precursor layers. Whilst no evidence of alkali incorporation is detected by energy dispersive X-ray analysis, clear evidence is seen in time-of-flight secondary ion mass spectrometry measurements. The implications of this are discussed in terms of reported effects on device performance

Improving effect of metal and oxide nanoparticles encapsulated in porous silica on fermentative biohydrogen production by Clostridium butyricum.

peer reviewedaudience: researcher, professional, student, popularizationThis paper investigated the enhancement effect of nanometre-sized metallic (Pd, Ag and Cu) or metallic oxide (Fe(x)O(y)) nanoparticles on fermentative hydrogen production from glucose by a Clostridium butyricum strain. These nanoparticles (NP) of about 2-3nm were encapsulated in porous silica (SiO(2)) and were added at very low concentration (10(-6)molL(-1)) in batch hydrogen production test. The cultures containing iron oxide NP produced 38% more hydrogen with a higher maximum H(2) production rate (HPR) of 58% than those without NP or with silica particles only. The iron oxide NP were used in a 2.5L sequencing-batch reactor and showed no significant effect on the yields (established at 2.2mol(hydrogen)mol(glucose)(-1)) but an improvement of the HPR (+113%, reaching a maximum HPR of 86mL(hydrogen)L(-1)h(-1)). These results suggest an improvement of the electron transfers trough some combinations between enzymatic activity and inorganic materials.Etude de la production d'hydrogène par les bactéries anaérobies chimiotrophes (dark-fermentation

A dual-application poly (DL-lactic-co-glycolic) acid (PLGA)-chitosan composite scaffold for potential use in bone tissue engineering

The development of patient-friendly alternatives to bone-graft procedures is the driving force for new frontiers in bone tissue engineering. Poly (DL-lactic-co-glycolic acid), (PLGA) and chitosan are well-studied and easy-to-process polymers from which scaffolds can be fabricated. In this study, a novel dual-application scaffold system was formulated from porous PLGA and protein-loaded PLGA/chitosan microspheres. Physicochemical and in vitro protein release attributes were established. The therapeutic relevance, cytocompatibility with primary human mesenchymal stem cells (hMSCs) and osteogenic properties were tested. There was a significant reduction in burst release from the composite PLGA/chitosan microspheres compared with PLGA alone. Scaffolds sintered from porous microspheres at 37°C were significantly stronger than the PLGA control, with compressive strengths of 0.846 ± 0.272 MPa and 0.406 ± 0.265 MPa, respectively (p < 0.05). The formulation also sintered at 37°C following injection through a needle, demonstrating its injectable potential. The scaffolds demonstrated cytocompatibility, with increased cell numbers observed over an 8-day study period. Von Kossa and immunostaining of the hMSC-scaffolds confirmed their osteogenic potential with the ability to sinter at 37°C in situ

Three-dimensional principal component scores plot for PC 1, 2 and 3 for the ToF-SIMS spectra (no. m/z peaks = 822) of partially exsheathed L₃ <i>N</i>. <i>americanus</i> in both negative (no. m/z peaks = 429) and positive polarity (no. m/z peaks = 393).

<p>PCA analysis was conducted on 24 different regions of interest (cuticle = 12, sheath = 12).</p

ハナレアイ ツツ トモ ニ イキル チンパンジー

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling <i>in situ</i> grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insights into the <i>in situ</i> grafting of diazonium. We discovered that the connecting bond is a nitro group which is covalently linked to a carbon on the aryl amine. The increased understanding of the surface chemistry gained through these studies enabled us to fabricate surfaces with optimized electron transfer kinetics. The knowledge gained from these studies allows for the rational design and tuning of the electronic properties of ITO-based conducting surfaces important for development of various electronic applications

Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-l-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray photoelectron spectroscopy (XPS) or time-of-flight secondary ion mass spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter representing a 50% relative error for a nominal volume fraction of 0.2. Error was predominantly caused by inadequacy in the ability to compensate for primary ion intensity variations and the matrix effect in SIMS. Matrix effects in these materials appear to be more pronounced as the number of atoms in both the primary analytical ion and the secondary ion increase. Using the participants’ data we show that organic SIMS matrix effects can be measured and are remarkably consistent between instruments. We provide recommendations for identifying and compensating for matrix effects. Finally, we demonstrate, using a simple normalization method, that virtually all ToF-SIMS participants could have obtained estimates of volume fraction that were at least as accurate and consistent as XPS