Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices. This work reports the preparation of amorphous TiO2 nanopowders, which were obtained through the anodization of titanium in ethaline media. The obtained amorphous TiO2 was used to obtain TiO2-decorated carbon (obtained through the carbonization of glycogen precursor from mussel cooking wastewater, under N2 atmosphere) composites through three different methods: electrochemical in-situ attachment of TiO2 nanopowders to the carbon matrix using ultrasounds and sonication in ethaline. Commercial TiO2 was used as the comparison material. Morphology, composition, and structure analysis were performed, followed by the electrochemical analysis in ethaline electrolyte. The in-situ attachment of amorphous TiO2 to the carbon matrix shows the most promising electrochemical performance of 956 F g-1 at 1 A g-1 for the three-electrode cell setup, with 100%  and 98% capacitance retention after 1000 and 10000 cycles. On a two-electrode symmetric solid-state electrolyte cell, the gravimetric capacitance is 1251 F g-1, at 1 A g-1, with 90% and 78% capacitance retention after 1000 and 10000 cycles, respectively.

Fabrication of Co-Sb Junction Nanowires by Galvanostatic Electrodeposition

This work presents the synthesis of CoSb3 one-dimensional (1D) thermoelectric nanomaterials using electrodeposition under galvanostatic conditions and polycarbonate membranes as a template (50 nm diameter pores). Cyclic voltammetry measurements have been performed to get preliminary information on the electrochemical reduction process of the involved species. Different current density values in the range 1-4 mA cm-2 have been applied, leading to the formation of nanowires (NWs) and micro- and nanomushroom caps, as evidenced by the scanning electron microscopy and scanning transmission electron microscopy investigations. Through fine-tuning of the current density the desired Co/Sb atomic ratio could be achieved. Energy-dispersive X-ray spectroscopy analysis showed the formation of CoSb3 at 1.4 mA cm-2, and it has also been confirmed by high-resolution transmission electron microscopy and micro-Raman spectroscopy. In this work, we present for the first time the fabrication of a CoSb3-CoxSby heterojunction on the same NW exhibiting Sb-rich and Co-rich alloy segments, prepared by electrodeposition from the same electrolyte by simply varying the applied current density.

The Influence of Reflowing Process on Electrodeposited Sn-Cu-Ni Lead-Free Solder Alloy

Sn-Cu-Ni lead-free solder alloy electrodeposited on copper substrate from a deep eutectic solvent (DES)-based electrolyte under direct current (DC) and pulsed current (PC) was subjected to a reflowing process at the industrial company MIBATRON S.R.L. (Otopeni, Romania). The alteration of the alloy's composition and anti-corrosive properties upon exposure to the reflow process were investigated via Scanning Electron Microscopy (SEM-EDX), X-ray diffraction (XRD), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Corrosion studies conducted in sodium chloride solution revealed that the system obtained under the DC plating mode (Sn-Cu-Ni-DC) exhibited enhanced anti-corrosive properties compared to the system obtained under PC (Sn-Cu-Ni-PC) after reflowing. However, prior to reflowing, the opposite effect was observed, with Sn-Cu-Ni-PC showing improved anti-corrosive properties. These changes in anti-corrosive behavior were attributed to the modification of the alloy's composition during the reflowing process.

Renewable Carbon Materials as Electrodes for High-Performance Supercapacitors: From Marine Biowaste to High Specific Surface Area Porous Biocarbons

Waste, in particular, biowaste, can be a valuable source of novel carbon materials. Renewable carbon materials, such as biomass-derived carbons, have gained significant attention recently as potential electrode materials for various electrochemical devices, including batteries and supercapacitors. The importance of renewable carbon materials as electrodes can be attributed to their sustainability, low cost, high purity, high surface area, and tailored properties. Fish waste recovered from the fish processing industry can be used for energy applications and prioritizing the circular economy principles. Herein, a method is proposed to prepare a high surface area biocarbon from glycogen extracted from mussel cooking wastewater. The biocarbon materials were characterized using a Brunauer-Emmett-Teller surface area analyzer to determine the specific surface area and pore size and by scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman analysis, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical characterization was performed using a three-electrode system, utilizing a choline chloride-based deep eutectic solvent (DES) as an eco-friendly and sustainable electrolyte. Optimal time and temperature allowed the preparation of glycogen-based carbon materials, with a specific surface area of 1526 m² g^-1, a pore volume of 0.38 cm³ g^-1, and an associated specific capacitance of 657 F g^-1 at a current density of 1 A g^-1, at 30 °C. The optimal material was scaled up to a two-electrode supercapacitor using a DES-based solid-state electrolyte (SSE@DES). This prototype delivered a maximum capacitance of 703 F g^-1 at a 1 A g^-1 of current density, showing 75% capacitance retention over 1000 cycles, delivering the highest energy density of 0.335 W h kg^-1 and power density of 1341 W kg^-1. Marine waste can be a sustainable source for producing nanoporous carbon materials to be incorporated as electrode materials in energy storage devices.

Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure

Activated carbons have been previously produced from a huge variety of biomaterials often reporting advantages of using certain precursors. Here we used pine cones, spruce cones, larch cones and a pine bark/wood chip mixture to produce activated carbons in order to verify the influence of the precursor on properties of the final materials. The biochars were converted into activated carbons with extremely high BET surface area up to ∼3500 m² g^-1 (among the highest reported) using identical carbonization and KOH activation procedures. The activated carbons produced from all precursors demonstrated similar specific surface area (SSA), pore size distribution and performance to electrodes in supercapacitors. Activated carbons produced from wood waste appeared to be also very similar to "activated graphene" prepared by the same KOH procedure. Hydrogen sorption of AC follows expected uptake vs. SSA trends and energy storage parameters of supercapacitor electrodes prepared from AC are very similar for all tested precursors. It can be concluded that the type of precursor (biomaterial or reduced graphene oxide) has smaller importance for producing high surface area activated carbons compared to details of carbonization and activation. Nearly all kinds of wood waste provided by the forest industry can possibly be converted into high quality AC suitable for preparation of electrode materials.

Chitins from Seafood Waste as Sustainable Porous Carbon Precursors for the Development of Eco-Friendly Supercapacitors

Carbon materials derived from marine waste have been drawing attention for supercapacitor applications. In this work, chitins from squid and prawn marine wastes were used as carbon precursors for further application as electrodes for energy storage devices. Chitins were obtained through a deproteinization method based on enzymatic hydrolysis as an alternative to chemical hydrolysis as commonly presented in the literature. The obtained porous carbons were characterized using a BET surface area analyzer to determine the specific surface area and pore size, as well as scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Raman spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), to characterize their morphology, composition, and structure. The electrochemical characterization was performed using a glassy carbon (GC) electrode modified with marine waste-based porous carbons as the working electrode through cyclic voltammetry and galvanostatic charge/discharge using ethaline, a choline chloride-based deep eutectic solvent (DES), as an eco-friendly and sustainable electrolyte. Squid and prawn chitin-based carbons presented a surface area of 149.3 m² g^-1 and 85.0 m² g^-1, pore volume of 0.053 cm³ g^-1 and 0.029 cm³ g^-1, and an associated specific capacitance of 20 and 15 F g^-1 at 1 A g^-1, respectively. Preliminary studies were performed to understand the effect of -OH groups on the chitin-based carbon surface with DES as an electrolyte, as well as the effect of aqueous electrolytes (1 mol L^-1 sulphuric acid (H₂SO₄) and 1 mol L^-1 potassium hydroxide (KOH)) on the capacitance and retention of the half-cell set up. It is provided, for the first time, the use of chitin-based carbon materials obtained through a one-step carbonization process combined with an eco-friendly DES electrolyte for potential application in energy storage devices.

Synthesis of Copper Nanostructures for Non-Enzymatic Glucose Sensors via Direct-Current Magnetron Sputtering

In this paper, Cu nanocolumnar structure electrodes are synthetized using a clean and easy-to-scale-up direct-current magnetron sputtering (DC-MS) technique for non-enzymatic glucose sensing. The nanocolumnar structure increases the active surface area of the deposit, with the nanocolumns showing a mean size diameter of 121.0 nm ± 27.2 and a length of 2.52 µm ± 0.23. A scanning transmission electron (STEM) analysis shows the presence of Cu and a small amount of Cu₂O. The behavior of the electrodes in alkaline environments and the electrochemical affinity of the Cu nanocolumns (CuNCs) towards the electro-oxidation of glucose are investigated using cyclic voltammetry (CV). After performing CV in NaOH solution, the columnar structures present corrosion products containing Cu₂O, as revealed by STEM and X-ray diffraction (XRD) analyses. The amperometric responses of the CuNCs to the successive addition of glucose show a linear range up to 2 mM and a limit of detection of 5.2 µM. Furthermore, the electrodes are free from chloride poisoning, and they are insensitive to dopamine, uric acid, ascorbic acid, and acetaminophen at their physiological concentrations.

Synthesis and Characterization of Coordination Compound [Eu(µ2-OC2H5)(btfa)(NO3)(phen)]2phen with High Luminescence Efficiency

A high-luminescent, blue-light excitable europium(III) coordination complex, [Eu(µ₂-OC₂H₅)(btfa)(NO₃)(phen)]₂phen (1) {btfa = benzoyl trifluoroacetone, phen = 1,10-phenantroline}, has been synthesized and investigated. The complex was characterized by infrared (IR) and photoluminescence (PL) spectroscopy. The PL emission spectra of powder samples registered in a range of 10.7-300 K exhibit characteristic metal-centered luminescence bands, assigned to internal radiative transitions of the Eu³⁺ ion, ⁵D₁→⁷F_j and ⁵D₀→⁷F_j (j = 0-4). The high-resolution spectrum of the transition ⁵D₀→⁷F₀ shows that it consists of two narrow components, separated by 0.96 meV, which indicates the presence in the matrix of two different sites of the Eu³⁺ ion. The splitting pattern of ⁵D₀→⁷F_j (j = 0-4) transitions indicates that europium ions are located in a low-symmetry environment. The absolute quantum yield and the sensitization efficiency were determined to be 49.2% and 89.3%, respectively. The complex can be excited with low-cost lasers at around 405 nm and is attractive for potential applications in optoelectronics and biochemistry.

Interaction of Mg Alloy with PLA Electrospun Nanofibers Coating in Understanding Changes of Corrosion, Wettability, and pH

A modified biodegradable magnesium alloy (AZ31, 96 wt% Mg, 3 wt% Al, and 1 wt% Zn) with polylactic acid (PLA) nanofibers was obtained by the electrospinning technique. The presence of PLA nanofibers was evidenced using Fourier transform infrared spectroscopy (FT-IR) and using an scanning electronic microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDX) module. The degradation behavior of an uncoated Mg alloy and a Mg alloy coated with PLA was evaluated through hydrogen evolution, pH, and electrochemical measurements in simulated body fluid. Contact angle measurements showed a shift from hydrophilic towards the hydrophobic character of the alloy after its coating with PLA nanofibers. Furthermore, the electrochemical measurement results show that the Mg based alloy coated with PLA inhibits hydrogen evolution, thus being less prone to degradation. The aim of this research is not only to reduce the corrosion rate of Mg alloy and to improve its properties with the help of polylactic acid coating, but also to provide a study to understand the hydrophilic–hydrophobic balance of biodegradable magnesium based on surface energy investigations. Taking into account corrosion rate, wettability, and pH changes, an empiric model of the interaction of Mg alloy with PLA nanofibers is proposed.

The Water-Based Synthesis of Platinum Nanoparticles Using KrF Excimer Laser Ablation

Our work presents, for the first time, a comprehensive study of the synthesis of fully metallic platinum nanoparticles (Pt-NPs) involving the ablation process in double distilled water using a KrF excimer laser. To obtain detailed information on Pt-NP morphology and optical properties, prepared colloids were characterized using High Resolution Scanning Transmission Electron Microscopy (HR-STEM) with advanced capabilities for Energy Dispersive X-ray Analysis (EDX), UV/Vis optical spectroscopy, and Direct Analysis in Real Time—Mass Spectrometry (DART-MS). The influence of the applied laser fluence and laser repetition rate (RR) values on the characteristics of the obtained Pt-NPs and the ablation process, respectively, were also analyzed. Spherical and spherical-like nanoparticles exhibiting aggregation were produced. The Pt-NP mean size values were between 2.2 ± 1.2 nm and 4.0 ± 1.0 nm, while their interplanar distance measurements showed a face-centered cubic (FFC) Pt lattice (111), as revealed by HR–STEM measurements, for all investigated samples. The smallest mean size of 2.2 nm of the Pt-NPs was obtained using a 2.3 J cm⁻² laser fluence at a 10 Hz RR, and the narrowest size distribution of the NPs was obtained with a 2.3 J cm⁻² laser fluence at a 40 Hz RR. A linear dependence of the Pt-NP diameters versus the laser repetition rate was found at a constant fluence of 2.3 J cm⁻². The proposed eco-friendly synthesis route of Pt-NPs, because of its relative simplicity, has the potential for use in industrial production.

Characterization of Carbon Nanomaterials Dispersions: Can Metal Decoration of MWCNTs Improve Their Physicochemical Properties?

A suitable dispersion of carbon materials (e.g., carbon nanotubes (CNTs)) in an appropriate dispersant media, is a prerequisite for many technological applications (e.g., additive purposes, functionalization, mechanical reinforced materials for electrolytes and electrodes for energy storage applications, etc.). Deep eutectic solvents (DES) have been considered as a promising "green" alternative, providing a versatile replacement to volatile organic solvents due to their unique physical-chemical properties, being recognized as low-volatility fluids with great dispersant ability. The present work aims to contribute to appraise the effect of the presence of MWCNTs and Ag-functionalized MWCNTs on the physicochemical properties (viscosity, density, conductivity, surface tension and refractive index) of glyceline (choline chloride and glycerol, 1:2), a Type III DES. To benefit from possible synergetic effects, AgMWCNTs were prepared through pulse reverse electrodeposition of Ag nanoparticles into MWCNTs. Pristine MWCNTs were used as reference material and water as reference dispersant media for comparison purposes. The effect of temperature (20 to 60 °C) and concentration on the physicochemical properties of the carbon dispersions (0.2-1.0 mg cm^-3) were assessed. In all assessed physicochemical properties, AgMWCNTs outperformed pristine MWCNTs dispersions. A paradoxical effect was found in the viscosity trend in glyceline media, in which a marked decrease in the viscosity was found for the MWCNTs and AgMWCNTs materials at lower temperatures. All physicochemical parameters were statistically analyzed using a two-way analysis of variance (ANOVA), at a 5% level of significance.

Preliminary Study on Light-Activated Antimicrobial Agents as Photocatalytic Method for Protection of Surfaces with Increased Risk of Infections

Preventing and controlling the spread of multidrug-resistant (MDR) bacteria implicated in healthcare-associated infections is the greatest challenge of the health systems. In recent decades, research has shown the need for passive antibacterial protection of surfaces in order to reduce the microbial load and microbial biofilm development, frequently associated with transmission of infections. The aim of the present study is to analyze the efficiency of photocatalytic antimicrobial protection methods of surfaces using the new photocatalytic paint activated by light in the visible spectrum. The new composition is characterized by a wide range of analytical methods, such as UV-VIS spectroscopy, electron microscopy (SEM), X-ray powder diffraction (PXRD) or X-ray photoelectron spectroscopy (XPS). The photocatalytic activity in the UV-A was compared with the one in the visible light spectrum using an internal method developed on the basis of DIN 52980: 2008-10 standard and ISO 10678—2010 standard. Migration of metal ions in the composition was tested based on SR EN1186-3: 2003 standard. The new photocatalytic antimicrobial method uses a type of photocatalytic paint that is active in the visible spectral range and generates reactive oxygen species with inhibitory effect against all tested microbial strains.

Swelling-Based Distributed Chemical Sensing with Standard Acrylate Coated Optical Fibers

Distributed chemical sensing is demonstrated using standard acrylate coated optical fibers. Swelling of the polymer coating induces strain in the fiber’s silica core provoking a local refractive index change which is detectable all along an optical fiber by advanced distributed sensing techniques. Thermal effects can be discriminated from strain using uncoated fiber segments, leading to more accurate strain readings. The concept has been validated by measuring strain responses of various aqueous and organic solvents and different chain length alkanes and blends thereof. Although demonstrated on a short range of two meters using optical frequency-domain reflectometry, the technique can be applied to many kilometer-long fiber installations. Low-cost and insensitive to corrosion and electromagnetic radiation, along with the possibility to interrogate thousands of independent measurement points along a single optical fiber, this novel technique is likely to find applications in environmental monitoring, food analysis, agriculture, water quality monitoring, or medical diagnostics.

Liquid Flow Meter by Fiber-Optic Sensing of Heat Propagation

Monitoring fluid flow rates is imperative for a variety of industries including biomedical engineering, chemical engineering, the food industry, and the oil and gas industries. We propose a flow meter that, unlike turbine or pressure-based sensors, is not flow intrusive, requires zero maintenance, has low risk of clogging, and is compatible with harsh conditions. Using optical fiber sensing, we monitor the temperature distribution along a fluid conduit. Pulsed heat injection locally elevates the fluid’s temperature, and from the propagation velocity of the heat downstream, the fluid’s velocity is determined. The method is experimentally validated for water and ethanol using optical frequency-domain reflectometry (OFDR) with millimetric spatial resolution over a 1.2 m-long conduit. Results demonstrate that such sensing yields accurate data with a linear response. By changing the optical fiber interrogation to time-domain distributed sensing approaches, the proposed technique can be scaled to cover sensing ranges of several tens of kilometers. On the other extreme, miniaturization for instance by using integrated optical waveguides could potentially bring this flow monitoring technique to microfluidic systems or open future avenues for novel “lab-in-a-fiber” technologies with biomedical applications.

Nanomechanical properties of zirconium anodized in a mixture of electrolytes with fluoride ions

The present work introduces nanostructured Zr as a possible choice of metallic implant biomaterial in competition with titanium and its new alloys. The paper reports on the preparation of anodized zirconium in a mixture of electrolytes with fluoride ions, 1 M (NH₄)2SO₄ + 0.15 M NH₄F + distilled water, at 20 V. The obtained nanostructures were investigated by SEM, EDX, XRD and AFM techniques. The SEM - EDX longitudinal and cross sectional analysis revealed the morphology of the formed oxide layers and their thicknesses, which were found to be 7.45 ± 0.18 μm. The mean nanopores' diameter was calculated as 15.8 ± 3.3 nm. The XRD investigations enabled the evaluation of crystallite sizes and texture coefficients for zirconium and zirconium oxide containing samples. The inhibition effect against Escherichia coli and Streptococcus Aureus bacteria was evaluated and discussed as well. The AFM studies revealed that the nano-porous Zr has similar hardness parameter as the uncoated Zr, but lower surface adhesion force that could be translated into improved properties in terms of antimicrobial effects, as confirmed by its inhibition index, which makes it a very promising material for bio-medical applications.

Electrochemical Non-Enzymatic Detection of Glucose Based on 3D Electroformed Copper on Ni Foam Nanostructures

Despite the fact that the electrochemical biosensors based on glucose oxidase represent the golden standard for the management of diabetes, the elaboration of nonenzymatic sensors became extensively studied as an out-of-the-box concept that aims to simplify the existing approach. An important point of view is represented by the low price of the sensing device that has positive effects for both end-users and healthcare systems. The enzyme-free sensors based on low-cost materials such as transition metals have similar analytical properties to the commercial ones while eliminating the issues associated with the presence of the enzyme, such as the stability issues and limited shelf-life. The development of nanoporous nanomaterials for biomedical applications and electrocatalysis was referred to as an alternative to the conventional methods due to their enlarged area, electrical properties, ease of functionalization and not least to their low cost. Herein, we report the development of an electrochemical nonenzymatic sensor for glucose based on 3D copper nanostructures with Ni foams as promotor of the enhanced nanoporous morphology. The sensors were successfully tested in the presence of the designated target, even in the presence of common interference agents found in biological samples.

Band tail state related photoluminescence and photoresponse of ZnMgO solid solution nanostructured films

A series of Zn1- x Mg x O thin films with the composition range x = 0.00-0.40 has been prepared by sol-gel spin coating on Si substrates with a post-deposition thermal treatment in the temperature range of 400-650 °C. The morphology of the films was investigated by scanning electron microscopy and atomic force microscopy while their light emission properties were studied by photoluminescence spectroscopy under excitation at 325 nm. It was found that annealing at 500 °C leads to the production of macroscopically homogeneous wurtzite phase films, while thermal treatment at higher or lower temperature results in the degradation of the morphology, or in the formation of ZnO particles embedded into the ZnMgO matrix, respectively. Local compositional fluctuations leading to the formation of deep band tails in the gap were deduced from photoluminescence spectra. A model for the band tail distribution in the bandgap is proposed as a function of the alloy composition. Thin films were also prepared by aerosol spray pyrolysis deposition using the same sol-gel precursors for the purpose of comparison. The prepared films were tested for photodetector applications.

Eighteen Months Follow-Up with Patient-Centered Outcomes Assessment of Complete Dentures Manufactured Using a Hybrid Nanocomposite and Additive CAD/CAM Protocol

Abstract: The present study aimed to assess the eighteen month follow-up patient-centered outcomes of a simple and predictable protocol for 3D-printed functional complete dentures manufactured using an improved poly(methyl methacrylate) (PMMA)-nanoTiO2. A detailed morphological and structural characterization of the PMMA-TiO2 nanocomposite, using SEM, EDX, XRD, and AFM, after 3D-printing procedure and post-wearing micro-CT, was also performed.

METHODS

A total of 35 fully edentulous patients were enrolled in this prospective study. A 0.4% TiO2-nanoparticle-reinforced PMMA composite with improved mechanical strength, morphologically and structurally characterized, was used according to an additive computer-aided design and computer-aided manufacturing (CAD/CAM) protocol for complete denture fabrication. The protocol proposed involved a three-step appointment process. Before denture insertion, 1 week, 12 month, and 18-month follow up patients were evaluated via the Visual Analogue Scale (VAS, 0-10) and Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT), with a higher score meaning poor quality of life.

RESULTS

A total of 45 complete denture sets were inserted. OHIP-EDENT scored significantly better after 18 months of denture wearing, 20.43 (±4.42) compared to 52.57 (±8.16) before treatment; mean VAS was improved for all parameters assessed.

CONCLUSIONS

Within the limitations of this study, we can state that the proposed workflow with the improved material used is a viable treatment option for patients diagnosed with complete edentulism.

Mass Flow Monitoring by Distributed Fiber Optical Temperature Sensing

We developed a novel method to monitor mass flow based on distributed fiber optical temperature sensing. Examination of the temporal and spatial temperature distribution along the entire length of a locally heated fluidic conduit reveals heat flow under forced convection. Our experimental results are in good agreement with two-dimensional finite element analysis that couples fluid dynamic and heat transfer equations. Through analysis of the temperature distribution bidirectional flow rates can be measured over three orders of magnitude. The technique is not flow intrusive, works in harsh conditions, including high-temperatures, high pressures, corrosive media, and strong electromagnetic environments. We demonstrate a first experimental implementation on a short fluidic system with a length of one meter. This range covers many applications such as low volume drug delivery, diagnostics, as well as process and automation technology. Yet, the technique can, without restrictions, be applied to long range installations. Existing fiber optics infrastructures, for instance on oil pipelines or down hole installations, would only require the addition of a heat source to enable reliable flow monitoring capability.

Eco-Friendly Push-Coated Polymer Solar Cells with No Active Material Wastes Yield Power Conversion Efficiencies over 5.5

Push-coating is a simple process that can be employed for extremely low-cost polymer electronic device production. Here, we demonstrate its application to the fabrication of poly(2,7-carbazole- alt-dithienylbenzothiadiazole) (PCDTBT):[6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) active layers processed in air, yielding similar photovoltaic performances as thermally annealed spin-coated thin films when used in inverted polymer solar cells (PSCs). During push-coating, the polydimethylsiloxane layer temporarily traps the deposition solvent, resulting in simultaneous film formation and solvent annealing effect. This removes the necessity for a postdeposition thermal annealing step which is required for spin-coated PSCs to produce high photovoltaic performances. Optimized PSC active layers are produced with a push-coating time of 5 min at room temperature with 20 times less hazardous solvent and 40 times less active material than spin-coating. Annealed spin-coated active layers and active layers push-coated for 5 min both produce average power conversion efficiencies (PCEs) of 5.77%, while those push-coated for a shorter time of 1 min yield a slightly lower value of 5.59%. We demonstrate that, despite differences in their donor:acceptor vertical concentration gradients, unencapsulated PCDTBT:PC₇₁BM active layers push-coated for 1 min produce PSCs with similar operational stability and upscaling capacity as thermally annealed spin-coated ones. As fast device fabrication can be achieved with short-time push-coating, we further demonstrate the potential of this deposition technique by manufacturing push-coated PSC-based semitransparent photovoltaic devices with a PCE of 4.23%, relatively neutral colors and an average visible transparency of 40.2%. Our work thus confirms that push-coating is not limited to the widely employed poly(3-hexylthiophene-2,5-diyl) but can also be used with low band gap copolymers and opens the path to low-cost and eco-friendly, yet efficient and stable PSCs.

Activated graphene as a material for supercapacitor electrodes: effects of surface area, pore size distribution and hydrophilicity

Activated reduced graphene oxide (a-rGO) is a material with a rigid 3D porous structure and high specific surface area (SSA). Using variation of activation parameters and post-synthesis mechanical treatment we prepared two sets of materials with a broad range of BET (N2) SSA ∼1000-3000 m2 g-1, and significant differences in pore size distribution and oxygen content. The performance of activated graphene as an electrode in a supercapacitor with KOH electrolyte was correlated with the structural parameters of the materials and water sorption properties. a-rGO is a hydrophobic material as evidenced by the negligibly small BET (H2O) SSA determined using analysis of water vapor sorption isotherms. However, the total pore volume determined using water vapor sorption and sorption of liquid water is almost the same as the one found by analysis of nitrogen sorption isotherms. Ball milling is found to provide an improved bulk density of activated graphene and collapse of all pores except the smallest ones (<2 nm). A decrease in the activation temperature from 850 °C to 550 °C is found to result in materials with a narrow micropore size distribution and increased oxygen content. Elimination of mesopores using ball milling or a lower activation temperature provided materials with better specific capacitance despite a significant decrease (by ∼30%) of the BET (N2) SSA. The best gravimetric and volumetric capacitances in KOH electrolyte were achieved not for samples with the highest value of the BET (N2) SSA but for materials with 80-90% of the total pore volume in micropores and an increased BET (H2O) SSA. Comparing the performance of electrodes prepared using rGO and a-rGO shows that a more hydrophilic surface is favorable for charge storage in supercapacitors with KOH electrolyte.

Hybrid Materials Based on Multi-walled Carbon Nanotubes with Antimicrobial Properties

In the present paper were prepared four types of sample consisting of multi-walled carbon nanotubes functionalized with carboxyl groups (MWCNT-COOH being the reference sample) and further functionalized with ZnCl2, MgCl2, AgNO3 and CuCl2. The samples were submitted to scanning electron microscopy (SEM), Raman microscopy, scanning transmission electron microscopy (STEM), and determined the antimicrobial character.

AFM and SEM Characterization of Chemically Modified Electrodes Based on 5-[(azulen-1-yl) methylene]-2-thioxothiazolidin-4-one

Preparation and microscopy characterization of polymer modified glassy carbon electrodes based on (5-[(azulen-1-yl) methylene]-2-thioxothiazolidin-4-one (L) were reported. Atomic Force Microscopy was used to investigate the morphological and mechanical properties of the deposited polyL films onto glassy carbon. The topography images of the analyzed samples exhibited the presence of some columnar shape features onto the layer surfaces. The surface roughness of the layers deposited at constant charge calculated from topography images, increased with the more positive applied potential for controlled potential electrolysis. At different charges, the roughness parameter showed the same behavior for the layers obtained applying a constant potential without having a noticeable influence on the adhesion properties on the substrate. Analysis using scanning electron microscopy shows a relatively uniform surface arrangement of the polymer and the presence of some clusters which are disturbing the planarity. PolyL chemically modified electrodes have been used for heavy metal ions detection with best results for lead.

New sensor based on membranes with magnetic nano-inclusions for early diagnosis in periodontal disease

A series of sodium selective membranes with magnetic nano-inclusions using p-tertbutyl calix[4]arene as ionophore and polymeric matrix (polyvinyl chloride) have been developed, and the corresponding sodium selective sensors were obtained for the first time. A linear range was registered between 3.1 × 10^-5 and 10^-1moldm^-3 and near Nernstian electrochemical answer: 55.73mV/decade has been recoreded for PVC (polyvinyl chloride) - based sodium selective sensor, with a response time of 45s. Due to their small dimensions, sensors could be used for measuring ions from the gingival crevicular fluid directly into the peri-odontal pocket, avoiding the difficulties of collecting an appropriate amount of fluid for analysis. Alterations in the inorganic ions level could be evidenced with this new device, assisting the early diagnosis and prevention of periodontal disease.

Hydrogen Chemical Configuration and Thermal Stability in Tungsten Disulfide Nanoparticles Exposed to Hydrogen Plasma

The chemical configuration and interaction mechanism of hydrogen adsorbed in inorganic nanoparticles of WS₂ are investigated. Our recent approaches of using hydrogen activated by either microwave or radiofrequency plasma dramatically increased the efficiency of its adsorption on the nanoparticles surface. In the current work we make an emphasis on elucidation of the chemical configuration of the adsorbed hydrogen. This configuration is of primary importance as it affects its adsorption stability and possibility of release. To get insight on the chemical configuration, we combined the experimental analysis methods with theoretical modeling based on the density functional theory (DFT). Micro-Raman spectroscopy was used as a primary tool to elucidate chemical bonding of hydrogen and to distinguish between chemi- and physisorption. Hydrogen adsorbed in molecular form (H₂) was clearly identified in all the plasma-hydrogenated WS₂ nanoparticles samples. It was shown that the adsorbed hydrogen is generally stable under high vacuum conditions at room temperature, which implies its stability at the ambient atmosphere. A DFT model was developed to simulate the adsorption of hydrogen in the WS₂ nanoparticles. This model considers various adsorption sites and identifies the preferential locations of the adsorbed hydrogen in several WS₂ structures, demonstrating good concordance between theory and experiment and providing tools for optimizing of hydrogen exposure conditions and the type of substrate materials.

AMS analyses of I-129 from the Fukushima Daiichi nuclear accident in the Pacific Ocean waters of the Coast La Jolla--San Diego, USA

This paper presents the results of an experimental study we performed by using the Accelerator Mass Spectrometry (AMS) method with iodine 129 (T1/2 = 15.7 My), to determine the increase of the radionuclide content in the USA West Pacific Coast waters, two years after the March 2011 Fukushima Daiichi nuclear power plant accident. The collection of the water samples took place between April and July 2013 at regular intervals of time, from the Pacific Ocean, at the cove of La Jolla, San Diego, USA. The results of the experiments showed a significant increase of the radionuclide concentration during the late spring of 2013. Compared to the isotopic ratio (129)I/(127)I, measured at a 40 km distance, offshore of Fukushima and immediately after the accident, our results show an increase on the USA West Coast that was more than a 2.5 factor higher. Also, compared with the pre-Fukushima background values, our results show an isotopic ratio of about two orders of magnitude higher. A distinct feature of the reconstructed radioactive plume was that it traveled with a speed of 12 cm s(-1), which we estimated and is consistent with the zonal speed in the Pacific. We coupled our (129)I results with the measurements from the June 2011 KOK cruise and we derived the levels of activity for (3)H and (137)Cs. On the USA West Coast, they did not exceed the international regulatory limits.

Nanostructures: a platform for brain repair and augmentation

Nanoscale structures have been at the core of research efforts dealing with integration of nanotechnology into novel electronic devices for the last decade. Because the size of nanomaterials is of the same order of magnitude as biomolecules, these materials are valuable tools for nanoscale manipulation in a broad range of neurobiological systems. For instance, the unique electrical and optical properties of nanowires, nanotubes, and nanocables with vertical orientation, assembled in nanoscale arrays, have been used in many device applications such as sensors that hold the potential to augment brain functions. However, the challenge in creating nanowires/nanotubes or nanocables array-based sensors lies in making individual electrical connections fitting both the features of the brain and of the nanostructures. This review discusses two of the most important applications of nanostructures in neuroscience. First, the current approaches to create nanowires and nanocable structures are reviewed to critically evaluate their potential for developing unique nanostructure based sensors to improve recording and device performance to reduce noise and the detrimental effect of the interface on the tissue. Second, the implementation of nanomaterials in neurobiological and medical applications will be considered from the brain augmentation perspective. Novel applications for diagnosis and treatment of brain diseases such as multiple sclerosis, meningitis, stroke, epilepsy, Alzheimer's disease, schizophrenia, and autism will be considered. Because the blood brain barrier (BBB) has a defensive mechanism in preventing nanomaterials arrival to the brain, various strategies to help them to pass through the BBB will be discussed. Finally, the implementation of nanomaterials in neurobiological applications is addressed from the brain repair/augmentation perspective. These nanostructures at the interface between nanotechnology and neuroscience will play a pivotal role not only in addressing the multitude of brain disorders but also to repair or augment brain functions.

Making, Breaking and Sliding of Nanometer-Scale Contacts

The contact between an atomic force microscope tip and a sample surface can form an ideal single asperity of nanometer dimensions, where the interaction forces can be measured with sub- nanoNewton force resolution. Studies of contact, adhesion and friction for these nano-asperities have been carried out for a variety of tips and single crystal sample surfaces. The major result is the observation of proportionality between friction and true contact area for a variety of systems, and an impressive agreement with continuum mechanics models for contact area even at the nanometer scale. The relevant continuum models can in fact be understood in the framework of fracture mechanics.

Sensing dipole fields at atomic steps with combined scanning tunneling and force microscopy

The electric field of dipoles localized at the atomic steps of metal surfaces due to the Smoluchowski effect were measured from the electrostatic force exerted on the biased tip of a scanning tunneling microscope. By varying the tip-sample bias the contribution of the step dipole was separated from changes in the force due to van der Waals and polarization forces. Combined with electrostatic calculations, the method was used to determine the local dipole moment in steps of different heights on Au(111) and on the twofold surface of an Al-Ni-Co decagonal quasicrystal.