bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibody-Free Electrochemical Detection of Cortisol Using Molecularly Imprinted Polymer
Authors: Manickam Pandiaraj , Pasha Syed Khalid , Bhansali Shekhar
Published: February 2020

Cortisol, an important steroid hormone in the body plays a key role in several stress related diseases including post-traumatic stress disorder [1-2]. Its continuous detection at room temperature still remains a challenge for providing timely health care to patients suffering from such diseases. We report here a novel, highly sensitive, and selective electrochemical cortisol sensor using molecularly imprinted polymer (MIP). MIP are synthetic polymers having highly specific recognition sites selective towards the target analyte and considered to be the versatile, stable and cost-effective alternatives for the natural antibodies. The cortisol specific MIP film was prepared by in situ electropolymerization of pyrrole [3] monomer onto the electrode surface in the presence of cortisol as a template. After removing the cortisol by electrochemical over-oxidation, the specific imprinted sites created on the polymer matrix were used to detect cortisol using ferrocyanide/ferricyanide (K3[Fe(CN)6]/K4[Fe(CN)6]) as a redox mediator. The imprinted sites on the electrode were characterized by cyclic voltammetry and scanning electron microscopy. The effect of experimental variables on the current response such as, electro-polymerization cycles, template/monomer ratio, elution condition for target removal, pH of the supporting electrolyte, and rebinding time were also investigated and optimized. The MIP based cortisol sensor exhibited a good detection limit of 1 pM mL-1cortisol. Moreover, the sensor showed a good reusability, i.e., the sensitivity remained >90% after 6 cycles of elution/rebinding, while the sensitivity only decreased to 90% after 4 weeks of storage at room temperature.  Simplicity in preparation, high affinity towards cortisol, and stability superior to antibodies makes the MIP technology, a potential candidate for commercializing the cortisol sensor for point-of-care diagnosis.

References:

[1]   Rachel Yehuda, Sarah L Halligan, Robert Grossman, Childhood trauma and risk for PTSD: Relationship to intergenerational effects of trauma, parental PTSD, and cortisol excretion. Development and Psychopathology 13 (2001) 733–753.

[2]   Syed Khalid Pasha, Ajeet Kaushik, Abhay Vasudev, Shedra Amy Snipes, Shekhar Bhansali, Electrochemical Immunosensing of Saliva Cortisol, Journal of Electrochemial Society 161 (2014) B3077–B3032.

[3]   Manickam Pandiaraj, Niroj Kumar Sethy, Kalpana Bhargava, Vepa Kameswararao, Chandran Karunakaran, Designing label-free electrochemical immunosensors for cytochrome c using nanocomposites functionalized screen printed electrodes, Biosensors and Bioelectronics 54 (2014) 115–121.
Pattern Recognition of HER-2 in Whole Blood Samples Using Stochastic Sensors
Authors: Moldoveanu Iuliana , Stefan-van Staden Raluca-Ioana
Published: February 2020

Chitosan and maltodextrin based diamond paste sensors were design, and characterized for the assay of HER-2 a biomarker for breast cancer.

The “signatures” of HER-2 were recorded for each stochastic sensor, and further used to identify these analytes on the patterns obtained when whole blood was screened. Quantitative analysis was also performed using these sensors. The results obtained using the proposed sensors were correlating very well with those obtained using the standard methods used in clinical analysis (e.g., ELISA).

Acknowledgements This work was supported by UEFISCDI PNII Program Ideas 2011-2014, Contract nr. 123/05.10.2011 and by ERC-like-3/07.2012 program.
(Invited) A Chemiresistive Glucose Sensor Based on Polyaniline Nanowire Network
Authors: Song Edward , Choi Jin-Woo
Published: February 2020

A simple fabrication technique of a low cost and disposable glucose sensor is proposed and demonstrated.  The sensor consists of an inkjet-printed polyaniline nanowire network pattern as a chemiresistive sensing material and glucose oxidase with metallic nanoparticles as enzyme and catalyst for detecting glucose.

In this work, we propose the use of catalytic nanoparticles and glucose oxidase (GOx) in conjunction with polyaniline nanowires for the development of a printable glucose sensor that is simple, low cost and manufacturable on a large scale.  The working principle is as follows: glucose oxidase converts glucose into to gluconolactone and in the process releases hydrogen peroxide as a byproduct.  Hydrogen peroxide reacts with the catalytic nanoparticles to produce hydroxide ion resulting in an increase in pH.  Since the conductivity of polyaniline is pH sensitive, any production of hydrogen peroxide will lead to an increase in resistance of the polyaniline.  Hence the concentration of glucose can be determined by observing the change in the conduction current through the polyaniline-based chemiresistor.

Polyaniline nanowires were chemically synthesized and printed on a PET film by inkjet printing.  Subsequently, catalytic nanoparticles and glucose oxidase were deposited and dried on the patterned polyaniline nanowires.  The printed sensor was tested with glucose and the conduction current change was observed.  The concept demonstrated in this work can potentially lead to a fully printed biosensor.

Figure 1
Nanostructured Sensors for Determination of 3-(3,4-Dichlorophenyl)-1,1-Dimethylurea Based in Molecularly Imprinted Polymers (MIPs) Deposited in Screen Printed Carbon Nanotubes
Authors: Morales Gomero Juan Carlos , Fernández Cori Rey , Huayhuas Chipana Bryan Carlos , Taboada Sotomayor Pilar
Published: February 2020

A selectivity sensor based on molecularly imprinted polymers (MIP) was developed for determination of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (diuron) in environmental samples. The molecularly imprinted polymers (MIP) were synthesized using non-covalent interactions and they were selected based on computer modeling. For the construction of the sensor, screen-printed carbon nanotubes electrodes were modified with Nafion® and MIP/NIP (not imprinted polymer). We used cyclic voltammetry to monitor the electrochemical response and Square Voltammetry Wave, Chronoamperometry and Differential Pulse Voltammetry to quantification of diuron in a range of response 0 - 1.1 V in a phosphate buffer solution (pH=8). All parameters affecting the sensor were optimized. The system showed a linear response at concentrations of 0.1 ppm to 15.0 ppm in phosphate buffer solution 0.1 mol L-1 (pH=8) and the detection limit of 0.05 ppm. The sensor was applied in water samples obtained promising results.
Graphene Based Materials for Arsenic Sensing and Removal from Contaminated Water
Authors: Assirelli Alessandra , Ieffa Simona , Bernasconi Roberto , Nobili Luca , Magagnin Luca
Published: February 2020

Environmental pollution especially toxic gases, heavy metal ions and organic pollutants in air and water, caused by industry and agricultural activities, severely threaten ecological balance and human health, and have received extensive attention worldwide. Arsenic contamination of groundwater is a critical problem that aﬀects millions of people across the world and results in severe diseases such as skin or lung cancer and bladder cancer. Widespread arsenic contamination of groundwater has led to a massive epidemic of arsenic poisoning in Asia and America, especially such as India, Bangladesh, Vietnam, Cambodia, Thailand, southwest USA, Canada, Chile, and neighboring countries.

Graphene has become a promising material for many different applications, such as nanoelectronic devices, physical, chemical and biochemical sensors, transparent conductive films, clean energy devices, or nanocomposite formulation. Sensing applications using graphene sheets as transducers have experienced a surge in the last few years, especially for gas sensing platforms, or electrochemical sensors, because of the high electrical conductivity of graphene.

In this work, we investigate the synthesis of graphene by methane decomposition at 1000 °C onto free standing electrodeposited substrates, studying the effects of the electrochemical synthesis onto graphene quality. The growth of good quality graphene layers is also discussed in terms of the role played by grain boundaries and diffusion at the grain boundaries. As an advance of graphene studies, 2D graphene nanomaterials have been applied to arsenic sensing and removal from contaminated water. The work will discuss our latest studies and progresses on the application of graphene-based materials in the environmental protection and detection for arsenic contaminated waters. The work will present the use of graphene based electrodes for electrochemical sensing of arsenic; a similar approach will be discuss for arsenic removal, discussing kinetics and performances of the process.
The Effect of Distribution of Uvlight on Elastic Modulus of UV Cured Film in Roll-to-Roll Nanoimprint Process
Authors: Kondo Shunsuke , Taki Kentaro , Ito Hiroshi
Published: February 2020

The Roll-to-Roll UV nanoimprint process (R2RUVNIP) is a promising technology to fabricate nanostructure on flexible films. In nanoimprint process, there is an issue how to find a feasible operating condition to peel-off the UV resin from the mold. To produce a desired nanostructure by the R2RUVNIP, the conversion and surface elasticity of UV-cured resin in

the process are needed to be known precisely to optimize the UV intensity and line speed. In this study, a UV curable resin (1,6-bis(acryloyloxy)hexane) was cured in the roll-to-roll nanoimprint process. Then the conversion and surface elastic modulus of UV resin were measured with FT-IR and nano indenter, respectively. The effect of distribution of UV light on the roller mold was investigated. The sharp distribution of UV light was effective to increase surface elastic modulus at a given conversion of monomer.
Effects of Pt-Based Electrode Compositions on CO Sensing Properties of NASICON-Based Solid Electrolyte Gas Sensors
Authors: Shimizu Yasuhiro , Takeda Hirotaka , Ueda Taro , Kamada Kai , Hyodo Takeo
Published: February 2020

We have reported recently the potential of planar-type NASICON-based solid electrolyte gas sensors equipped with Pt mixed with Bi2O3as a sensing electrode and pristine Pt as a reference electrode [1].  This type of sensors could be operated at room temperature with sufficiently high CO response and selectivity.  The present study was directed to investigating the effects of the addition of various kinds of metal oxides to both the Pt sensing and reference electrodes on the CO sensing properties. 

  Pt paste (Tanaka Corp., TR-7907) mixed with an appropriate amount (n wt%) of a metal oxide (MO), which is denoted as Pt(nMO), and just Pt paste or another kind of Pt(nM’O) were applied on the same surface of the NASICON disc as a sensing and a counter electrode, respectively, and then were fired at 700ºC for 30 min in air. The sensor thus fabricated was denoted as Pt(nMO)/Pt or Pt(nMO)/Pt(nM’O).  The metal oxides tested were Bi2O3, La2O3, In2O3, V2O5, WO3 and CeO2.  The magnitude of gas response was defined as the difference in EMF (ΔEMF) measured between in a sample gas and in base air. 

  CO response properties of the sensors equipped with the pristine Pt reference electrode were found to depend on the kind of metal oxides added to the Pt sensing electrode.  CO response with a EMF change to a positive direction was observed with a Pt(15Bi2O3)/Pt sensor, whereas a Pt(15CeO2)/Pt sensor showed a EMF change to a negative direction, as shown in Fig. 1.  The operating temperature dependence of the CO response of sensors was also affected by the kind of the metal oxides added (see Fig. 2).  By referring such CO response properties of these Pt(15MO)/Pt sensors, a Pt(15Bi2O3)/Pt(15CeO2) sensor was fabricated and then its CO response properties were further investigated in detail.  The CO sensing performance of the Pt(15Bi2O3)/Pt(15CeO2) sensor in both dry and wet air atmosphere, including interferences from 300 ppm CO2, CH4, C3H6 and H2, will be reported in the presentation.

Reference

[1] H. Takeda, T. Ueda, T. Hyodo, Y. Shimizu, Abstract of the 10th Asian Conference on Chemical Sensors, Chiang Mai, Thailand, Nov. 11-14, p. 110 (2013).

Figure 1
(Invited) Ionic Liquids and Gas Sensor Applications
Authors: Zeng Xiangqun
Published: February 2020

This presentation will discuss the notable contributions to the sensor fields using ionic liquids from our laboratory. Ionic liquids (ILs) are excellent solvents that have wide varying gas solubility for common gases    and volatile organic molecules which have been demonstrated for the storage and delivery of gases that are flammable, and/or reactive. Ionic liquids also have good ionic conductivity and have been explored as nonvolatile and nonflammable electrolytes for many electrochemical device developments.  In the past ten years,   our laboratory has systematically investigated the redox mechanisms of common gases (i.e. CH4, NO2, SO2, H2, CO, CO2, O2)  and small organic molecules (methanol, ethanol, formaldehyde, formic acid etc.) in ILs and we have identified new reaction mechanisms for ionic liquid based gas sensor development which uniquely overcome many sensor performance challenges, especially those related to sensing capability and miniaturized sensor system implementation.  By synergistically utilizing the unique ionic liquid interface electrochemistry as well as molecular design and control of ionic liquid/conductive polymer composites, we have demonstrated new ionic liquid gas sensors enabling multiple gas detections with multiple modes detection principles via low cost and low power piezoelectric/QCM and electrochemical transducers that yields forward-thinking solutions to many gas sensors challenges, especially miniaturization and robustness.   The simplicity of the demonstrated detection principles allows for easy integration with engineering advancements such as portable electronics, networked sensing and next-generation monolithic implementation of autonomous sensors with the performance, cost, power, and operational lifetime characteristics to suit a broad range of applications.
Control of the Microstructure and the Magnetic and Magnetostrictive Properties of Electrodeposited Fe-Co-B Thin Films for Sensor Applications
Authors: Sheng Zhizhi , Zhang Kewei , Cheng Z.-Y.
Published: February 2020

Magnetostrictive materials with a soft magnetic response are the fundament for the development of some high performance sensors and actuators. Fe-Co-B was identified as a potential candidate for the development of high-frequency sensors and actuators. The key for using it is the preparation of Fe-Co-B thin film in proper microstructure and composition. In this study, electrochemical process is used to prepare the Fe-Co-B thin film under different conditions. The microstructure, magnetic and magnetostrictive properties of the thin film were characterized. The influence of the deposition condition and the solution concentration on the microstructure of the film was determined. Thin films with similar thickness deposited under low current density exhibited different structure from those deposited at higher current densities. It was due to the different elemental deposition rate at different current densities. At same current density, the thin films showed similar structure. Fe-Co-B thin films were soft magnetic materials. The hysteresis loop exhibited very slim indicating a novel soft magnetic property. It is known that the detection sensitivity of sensor depends on the size the sensor. The smaller the sensor is, the higher the sensitivity is. Additionally, the smaller the size, the higher the resonance frequency is. To get the sensor with higher sensitivity for higher frequency application, the micro/nano size sensors are needed. By combining the microfabrication method with electrochemical process, the miniaturized magnetostrictive sensors and actuators are prepared. The magnetostrictive thin film with a high sensor performance was obtained. Recently, micro strips with size of about 500 µm (lengh) × 100 µm (with) × (2~10 µm) (thickness) have been synthesized. The strips exhibited strong resonance frequency.
Electrochemical Characterization of Electrode Materials for Mixed-Potential Sensors
Authors: Reynolds Jonathan M. , Brown Shanice C. , Brosha Eric L. , Mukundan Rangachary , Garzon Fernando H , Kreller Cortney R
Published: February 2020

The Sensors and Electrochemical Devices group at LANL along with Electro-Science Laboratories (ESL) have developed a reproducible mixed potential NOx sensor for application in automotive emission control systems. The pre-commercial sensor has a perovskite working electrode (La1-xSrxCrO3) and a platinum counter electrode, and an Yttrium Stabilized Zirconium (YSZ) electrolyte layer on one side; with a resistive platinum heater on the other side. While the planar sensor that was developed has been extensively studied, several fundamental questions still need to be answered. This study will attempt to answer the question as to how the performance of the sensor changes as the composition of the working electrode is varied. This study uses a button cell in place of the stick sensor. This cell is constructed using the same materials and processes that formed the stick sensors except that it uses a dense YSZ disk with the electrodes on printed on opposite sides. The rationale for using the button cell is so that there is a reference electrode, in this case the platinum electrode, exposed to a controlled reference gas. In this study, we will investigate the change in the sensitivity and selectivity when the Strontium content of the perovskite electrode is changed. The changes will be characterized by using various electrochemical techniques. Information obtained from characterizing varying electrode materials in the button cell configuration will provide insight for tuning selectivity and sensitivity of future planar mixed-potential sensors.
Polypyrrole-Coated Carbon Nanotubes for Low Temperature Gas Sensor
Authors: Kim Anna , Lim Hana , Lee Ho-Nyun , Jae-Young Park , Yoo Bongyoung , Kim Hyun-Jong
Published: February 2020

Simple, low cost and energy efficient gas sensors for toxic gas measurements are in great demand for applications in industries and for environmental analysis. And, almost half a century ago, it has been already realized that semiconducting metal oxides have great potential as gas sensing materials, owing to the fact that chemical interaction of gas molecules with the semiconductor’s surface leads to changes in the electrical conductivity. Especially, SnO2 has been the most frequently used n-type semiconducting material for gas sensing. However, most of those inorganic sensors inherently suffer from some problems such as low selectivity, reduced life time, and relatively high operable temperature leading to increased power consumption which limit their versatility.

Recently, the conducting polymers have shown great promise in sensory applications. Delocalized electronic states combined with the restriction on the extent of delocalization leads to the formation of a large energy gap making most conductive polymers behave like p-type semiconductors. Advantages of using conducting polymers as sensing materials are ease of synthesis, fast response, low cost, and room temperature response.

In this study, polypyrrole-coated carbon nanotube(CNT) was prepared by chemical oxidation polymerization of pyrrole on the surface-functionalized carbon nanotube in the presence of FeCl3. As increasing the concentration of pyrrole, the thickness of polypyrrole layer on the surface of CNT was gradually increased. The obtained material was mixed with a solution containing gold(Au), platinum(Pt), silver(Ag) ion and simultaneously reduced by adding NaBH4 solution. The detection of carbon monoxide, toluene, and formaldehyde was systematically examined. Based on the gas sensing results, the thickness of polypyrrole, operating temperature, and concentration of metal catalyst were roughly optimized. Finally, the polypyrrole-coated CNT showed considerably promising gas sensing characteristics as compared to conventional SnO2 powder.
Citrus Limon Peel As a Component of Modified Carbon Paste Electrode for Voltammetric Determination of Cd(II)
Authors: Rajawat Deepak Singh , Satsangee Soami Piara
Published: February 2020

In the present communication a carbon paste electrode modified with Citrus limon peel was presented which shows enhanced activity toward metal determination in aqueous samples. Carbon Paste Electrode was prepared by mixing Graphite Powder, Nujol and Citrus Limon Peel. Prepared Carbon Paste Electrode was characterized using Cyclic Voltammetry, Electrochemical impedance study, Atomic Force Microscopy. Stripping voltammetry using differential pulse as input wave was used for metal determination. The performance of this new metal sensor was optimized for different preparation and experimental conditions. Different experimental conditions optimized are 12.5 % modifier, Acetate buffer as supporting electrolyte with pH 6, HCl as stripping solvent and 15 min accumulation time. The effect of surface active macro molecules was also studied. Enhancement in metal determination has been observed with the modified electrode for Pb (II) and Cd (II) as compared to the bare CPE. The limit of detection values observed are 64.4 ppb for Cd (II).
A Graphene-Zinc Nanorods Nano-Composite Film Sensor for Sensitive Determination of Tizanidine in Solubilized System
Authors: Jain Rajeev , Sinha Ankita
Published: February 2020

Abstract

A novel graphene/zinc nanorods nano-composite modified glassy carbon electrode (GR/ZnRs/GCE) based electrochemical sensor has been developed for the sensitive determination of a muscle relaxant drug tizanidine (TZ) in a solubilized system of cetyltrimethyl ammonium bromide (CTAB). The developed sensor was characterized by scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. It was found that the nanocomposite film of GR/ZnRs on GCE exhibits excellent electrocatalytic activity towards tizanidine reduction in britton robinson buffer at pH 6.5. Addition of CTAB to the solution containing drug enhanced the peak current and also lowers the reduction overpotential. Various kinetic parameters affecting the monitored electrocatalytic response were investigated and optimized for tizanidine determination. Under optimized conditions the developed sensor shows linear response over the concentration range of 1 ng mL-1 to 10 µg mL-1. The applicability of proposed sensor is further extended to in vitro determination of the drug in pharmaceutical formulation with an acceptable recovery from 99.63% to 100.98%. The fabricated (GR/ZnRs/GCE) sensor holds great promise for simple and sensitive quantification of tizanidine using electroanalytical techniques.

Keywords: Tizanidine (TZ), Graphene/Zinc nanorods modified glassy carbon electrode (GR/ZnRs/GCE), CTAB, Voltammetry.
Effects of Electrode Compressibility in Vanadium Redox Flow Batteries
Authors: Park Su Mi , Kim Hyun-Jong , Kim Haekyoung
Published: February 2020

Vanadium redox flow batteries (VRFBs) have been investigated for their potential utility as large energy storage systems due to their advantageous performances in terms of long cycle life, high energy efficiency, low cost, and flexible design. Carbon materials are typically used as electrodes in redox reactions and as a liquid electrolyte support. The activities, surface areas, and surface morphologies of carbon materials must be optimized to increase the redox flow battery performance. Here, the compressibility of carbon electrode was controlled with the thickness of carbon felts for the same thickness of electrode. The efficiencies with discharging current of VRFB were measured and characterized. The cyclic performances were also characterized with various flow rates. VRFB-2F has the lower compressibility than VRFB-3F. VRFB-2CF has the 5 mm thickness of carbon felt in 5 mm of electrode and VRFB3F has the 8 mm thickness of carbon felt in 5 mm of electrode thickness, which were compressed in VRFB flow cells.

Form the performance measurement with discharging current, VRFB-2CF exhibited 88.7 % of columbic efficiency (CE) and 63 % of energy efficiency (EE) at discharging current of 25mA/cm2, which are higher than those of VFRB-3CF (82.5 % of CE, 57.6 % of EE). VRFBs were tested for cyclic performances with 20 times under 50mA/cm2 of charging current and 50mA/cm2 of discharging current. VRFB-2CF exhibited over 90% of columbic efficiencies;  VRFB-3CF shows 80% of CE.  Energy efficiencies of VFRB-2CF are 63 %, 61.3 % and 56.8 % at 18cc/min, 36cc/min, and 54cc/min, respectively which are higher values than those of VRFB-3CF (55.3%, 50.7% and 52.3% at 18cc/min, 36cc/min, and 54cc/min, respectively).

The compactness of VRFB-3CF is higher than that if VRFB-2CF, which are concerned with the electrolyte-coupled mass transport. The effects of compactness of electrode will be discussed in terms of the mass and charge transfer polarization.
Carbon Nanotubes Grown on Metal Microelectrodes for Dopamine Detection
Authors: Yang Cheng , Venton Barbara Jill
Published: February 2020

Directly growing of carbon nanotubes (CNTs) on microelectrodes using chemical vapor deposition (CVD) can provide a dense and vertically aligned CNT film. Vertically-aligned CNTs grown on carbon fibers microelectrodes can detect dopamine, but the low conductivity of the carbon fiber may lead to slow electron transfer kinetics and the intrinsic electrochemical activity of carbon fibers makes evaluating the effect of CNT enhancement difficult.  In this study, we compared vertically-aligned CNTs gown on metal wires and carbon fibers as microelectrodes. Scanning electron microscopy shows that aligned CNTs can be grown on metal wires, particularly Tantalum and Niobium wires.  Using fast-scan cyclic voltammetry, CNT-coated niobium (CNT-Nb) microelectrodes had higher sensitivity and lower DEp values compared to CNTs grown on carbon fibers or other metal wires.  The limit of detection for dopamine at CNT-Nb microelectrodes is 11±1 nM, which is approximately five times lower than CNT grown CFMEs. Using Langmuir isotherms to model adsorption/desorption processes revealed that dopamine oxidation is more reversible at CNT based microelectrodes than that for CFMEs.  CNT-Nb microelectrodes were useful for monitoring stimulated dopamine release in anesthetized rats. Other neurochemicals could also be detected, including ascorbic acid, DOPAC, serotonin, adenosine, and histamine and the enhancement for dopamine was greater than ascorbic acid at CNT-Nb electrodes.  This study demonstrates that CNT-grown metal microelectrodes, especially CNTs grown on Nb are useful for sensitive monitoring of neurotransmitters.

Figure 1
Thermally Stable, Coke-Resistant Ni Nanoparticle Catalysts Prepared By Atomic/Molecular Layer Deposition for Dry Reforming of Methane
Authors: Shang Zeyu , Liang Xinhua
Published: February 2020

Dry reforming of methane (DRM) represents a promising approach for carbon dioxide utilization and syngas generation, and the syngas could be used for Fischer-Tropsch synthesis. Ni catalysts are more commercially attractive for DMR than noble metal catalysts. However, the stability of Ni catalysts is poor caused by sintering of the Ni particles and coking. Ni catalysts can be prepared by traditional method such as incipient wetness method; however, the Ni particle size is pretty large and not controllable. Previous studies indicated that coking could be decreased by using smaller Ni particles. In this study, we prepared Ni catalysts using atomic layer deposition (ALD) in a fluidized bed reactor. The Ni particles size is pretty small (3-5 nm). To increase the thermal stability of the nanoparticles, an ultra-thin porous alumina shell is coated on Ni nanoparticle surface. The porous alumina film is obtained by oxidation of molecular layer deposited aluminum alkoxide films. The core-shell catalysts exhibit excellent catalytic performance toward dry reforming of methane with carbon dioxide at 850 °C.
Activity of Nafion
Authors: Rathuwadu Nadeesha , Leddy Johna
Published: February 2020

The activity of protons and water content in Nafion films are considered for different electrolytes and electrolyte concentrations in the solution.  A model of activity effects in Nafion will allow optimization of operating conditions for systems such as fuel cells and sensors where proton exchange membranes and films significantly impact system response.  Cyclic voltammetry (CV) experiments were undertaken for Nafion films on electrodes with tris(2,2ʹ–bipyridyl)dichloro–ruthenium(II) hexahydrate (Ru(bpy)3
2+) as the redox probe.  The probe was equilibrated into Nafion from the electrolyte solution that contain different inert electrolytes at various concentrations.  The glassy carbon working electrode was modified with a recast Nafion film made by drop casting Nafion suspension and then evaporation of the casting solvents.  Terahertz spectroscopy experiments are used to find the dielectric constant of the recast Nafion film.  The dielectric constant in Nafion is needed to calculate activity coefficients in Nafion.

From the data obtained at the Nafion modified electrodes, ip (ip is peak current) varies with inert electrolyte cation.  For plots of ip versus v
1/2 (v is scan rate), inert electrolytes with the same cation had similar slopes where the observed peak currents ranked as H+ > Na+ > K+.  Cations with smaller hydration energies are more easily exchanged into Nafion.  The redox probe had no voltammetric response with high concentrations of the smaller cation electrolytes, consistent with little probe in the film.  However, even for small cation electrolytes, at sufficiently low electrolyte concentrations, Ru(bpy)3
2+ yields a voltammetric response. From the slopes of ip versus v
1/2, Cfilm Dfilm
1/2 is found, where Cfilm and Dfilm are the concentration and the diffusion coefficient of Ru(bpy)3
2+
 in the film. Cfilm Dfilm
1/2 does not change with the electrolyte concentration.  Convolution will further refine determination of Cfilm Dfilm
1/2 and the dielectric constant will allow further evaluation of activity effects in Nafion.
Comparisons in Voltammetry of Phenylenediamine Based Ureas on Platinum and Glassy Carbon Working Electrodes
Authors: Cedano Mario , Smith Diane K.
Published: February 2020

“Proton-coupled electron transfer” (PCET) reactions are essential to many of the fundamental chemical processes of biological systems. PCET has been studied for some time, but it is only recently that the role of H-bonding intermediates has been explored. One such H-bonding system under investigation consists of a phenylenediamine based urea that undergoes an apparent self-PCET reaction where one urea is oxidized by two electrons to the quinoidal cation, followed by the transfer of a proton and deactivation of the other half of the ureas. Reversibility of this process is due to the second electron transfer and proton transfer occurring through a H-bond complex between the oxidized urea and the dimethylamino group on an electroinactive urea.

In this study it was sought to observe possible differences in voltammetry of the phenylenediamine based urea system using different working electrode surfaces, in this case: platinum and glassy carbon working electrodes. Differences in voltammetry were observed between platinum and glassy carbon in methylene chloride. These differences appear to be due to faster heterogeneous electron transfer on glassy carbon than on platinum. In order to further explore this faster rate of electron transfer that is observed on glassy carbon, the working electrode surface was methylated, intentionally disrupting the electrode surface. The resulting voltammetric behavior of the phenylenediamine based urea system using this compromised electrode was similar to that of platinum, suggesting that the rate of electron transfer on glassy carbon was slowed down.

Further voltammetric experiments are being conducted in other solvents due to the solvent-dependence of the phenylenediamine based urea system. Possible differences in voltammetry between platinum and glassy carbon electrodes are currently being explored in dimethyl sulfoxide.
Pgs Synthesis with the Sulfated Titania Catalyst for the Esterificaiton
Authors: Hsu Sung Nien , Chou Kan-Sen
Published: February 2020

Biodegradable materials are more essential in the near future, specifically in the ECO issue. PSG is one of the biodegradable materials and also developed in the recently decade. PGS synthesis reacted with different loadings of Sulfated Titania that resulted in the esterification and shorten the reaction time efficiently. 0.3~0.5 g Sulfated Titania (TOS) could reach 6~7 hours for the PGS synthesis. Conversion of glycerol and sbacica acid is 82%, selectivity is 99%. Sulfated Titania and PGS characterized by the ICP-AEX, FT/IR, XRD, BET, TPA and GC-MS.
Nanoscale Investigation of Anodization Process of Titanium
Authors: He Kun , Lu Yu-Peng , Tolou Shokuhfar Tolou , Shahbzian-Yassar Reza
Published: February 2020

Titanium dioxide is one of the most versatile materials with applications ranging from biomedical and solar cells to photo catalysts. The main method to fabricate titanium dioxide is anodization. Numerous research works have been performed to determine the appropriate processing parameters for anodization such as electrolyte concentrations, voltage, anodization time, and so forth. During this research, a lab-on chip electrochemical setup was used to study the anodization process of the titanium in real time. The anodization process can be divided into three stages based on the current-time transient in aqueous electrolytes. In Stage I, oxide barrier layer forms and the electrical current decreases quickly. In stage II, electrical current subsequently rises and porous layer forms. In stage III, current becomes stable and the nanoscale TiO2 forms. For the anodization using fluoride containing electrolytes, the stage I and stage II can be finished in 20 minutes. Using the in situ setup, the current-time characteristics and the real time morphology evolution of the anode can be observed. The results provide fundamental insights of the mechanisms related to the nanoscale TiO2 formation and structure evolution in real time. The morphology of the nanotubes changes with different concentrations of fluoride ions and different amount of waters (0.1-5 wt%) in the electrolyte. The nanotubes change from smooth to ribbed when the water concentration is above a critical threshold. In this research, by applying different amount of water and concentration of fluoride ions, the effect of fluoride ion concentration and water on the morphology of nanotubes can be investigated.
Solid-State Reaction Assisted Synthesis of Co-Doped MnO2 Nano-Composite Materials for Supercapacitor
Authors: Feng Wanru , Zhang Guangli , He Ping , Lei Wen , Wen Jianwu , Wang Fu
Published: February 2020

Electrochemical supercapacitors are charge–storage devices that have greater power density and longer cycle life than batteries, and they possess higher energy density compared with conventional capacitors.  Based on the different operation mechanisms, supercapacitors can be classified into two different categories: double-layer capacitors and pseudocapacitors [1,2].  Recently, relatively cheap oxide alternatives with similar characteristics have been developed to replace ruthenium oxide as electrode materials for use in pseudo-capacitors due to their low cost and no-toxicity.  MnO2 has been used as one of the promising electrode materials for supercapacitor mainly because of its abundance in nature, low price, environment friendliness, wide charge/discharge potential range and large specific area [3].

In this work, a mechanically assisted solid-state reaction method was employed to prepare Co-doped MnO2 nanocomposites for supercapacitor electrode materials.  It was found that the specific capacitance of 2.3 wt% Co doped MnO2 composite electrode was up to 340.1 F g-1 in 1.0 M KCl solution (Figure 1).  Additionally, as prepared Co doped MnO2 composite electrode showed other desirable electrochemical properties, including good stable electrochemical properties, excellent reversibility and the long cycle life (Figure 2), demonstrating that it had potential advantages for the fabrication of electrochemical capacitor.

 

References

[1] Wen Lei, Ping He, Susu Zhang, Faqin Dong, Yongjun Ma. One-step triple-phase interfacial synthesis of polyaniline-coated polypyrrole composite and its application as electrode materials for supercapacitors. Journal of Power Sources, 2014, 266: 347-352.

[2] Wen Lei, Ping He, Yuhao Wang, Susu Zhang, Faqin Dong HongTao Liu. Soft template interfacial growth of novel ultralong polypyrrole nanowires for electrochemical energy storage. Electrochimica Acta, 2014, 132: 112-117.

[3] X Lang, A Hirata, T Fujita, M Chen. Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors. Nature Nanotechnology, 2011, 6: 232-236.

Figure 1
Exploration of Chemical Bonding Transformation Mapping to Assist Low-k Dielectric Nanostructure Fabrication
Authors: Chyan Oliver , Rimal Sirish , Mukherjee Tamal , Goswami Arindom , Ross Nick
Published: February 2020

In leading edge integrated circuit manufacture, reduction of RC time delay by incorporation of porous ultra-low k (ULK) interlayer dielectrics (ILD) into Cu interconnect nanostructure continues to pose major integration challenges. The main challenge is porosity induced to lower the dielectric constant of the ILD has the undesirable side effect of compromising its mechanical and chemical stability. As a result, these materials are more susceptible to the damages caused by RIE plasma etching processes. Besides the challenge of handling weak porous ULK materials, a lack of sensitive metrology to guide systematic development of plasma etching, restoration and cleaning processes is the major stumbling block. To assist in the overall integration effort, we have been actively exploring Multiple Internal Reflection Infrared Spectroscopy (MIR-IR) and associated IR spectroscopic techniques as a sensitive (sub-5nm) characterization tool to assist the fabrication process of ULK nanostructure with targeted critical dimension. In this paper, we will report new findings obtained on chemical bonding modification across fluorocarbon etch residues and low-k dielectric interface after manufacture relevant processing treatments including plasma etching, ashing, UV curing and post-etch cleaning. MIR-IR metrology showed useful spectroscopic details of chemical bonding transformations taking place during plasma etch and strip processing on both blanket and dielectric trench structures. The observed increase of Si-OH and C=O and the decrease of Si-CH3 IR absorption bands correlated well with increasing plasma induced damage, K increases verified by MIS structure, especially for more aggressive stripping process. With functional group-specific chemical derivatization, chemical bonding structure of 1-2 nm post-etch residue on porous low-k trench structure was established. UV-induced modification of fluorocarbon polymer residue to improve its subsequent wet cleaning removal was studied by FTIR, XPS and SEM.  The overall goal is to apply new insights on chemical bonding transformation mapping to achieve cleans-friendly plasma etches on creating ULK dielectric nanostructures with minimal dielectric damages.
Proton Channels on Molecular Electrocatlaysts for Hydrogenase Mimics
Authors: Shaw Wendy , Dutta Arnab , Roberts John
Published: February 2020

Hydrogenases interconvert H2 and protons at high rates and with high energy efficiencies, providing inspiration for the development of molecular catalysts.  Studies designed to determine how the protein scaffold can influence a catalytically active site have led to the synthesis of amino acid derivatives of [Ni(PR
2NR'
2)2]2+ complexes, [Ni(PCy
2NAmino acid
2)2]2+ (CyAA).  It is shown that these CyAA derivatives can electrochemically catalyze fully reversible H2 production/oxidation, a feature reminiscent of enzymes.  The reversibility is achieved in acidic aqueous solutions, 1 atm 25% H2/Ar, and elevated temperatures (tested up to 70 ¢ªC) for the glycine (CyGly), arginine (CyArg), and arginine methyl ester (CyArgOMe) derivatives. At pH=1 and 70 C, rates of up to ~300 s-1 H2 production and 20 s-1 H2 oxidation 348 K are observed.  The effect of higher pressure and the behavior of complexes without an outer coordination sphere will be discussed. These observations demonstrate that outer coordination sphere amino acids work in synergy with the active site in and can play an equally important role for synthetic molecular electrocatalysts as the protein scaffold does for redox active enzymes.
(Invited) Biological Applications of Nanoparticles for Reactive Oxygen Species (ROS) Scavenging and Sensing
Authors: Boghossian Ardemis Anoush , Sen Fatih , Gibbons Brenna , Sen Selda , Faltermeier Sean , Giraldo Juan Pablo , Zhang Cathy , Zhang Jingqing , Heller Daniel , Strano Michael S
Published: February 2020

Cerium oxide nanoparticles, or nanoceria (NC), offer a regenerative approach to scavenging reactive oxygen species (ROS). NC have been used to prevent retinal and neuronal degeneration, protecting cells against ROS and radiation damage. Unlike most scavengers, which undergo a depletion in activity upon ROS consumption, NC are regenerative; theoretically, they are able to scavenge for ROS indefinitely so long as a physiological pH is maintained. Our recent work has extended NC applications beyond the human body towards other biological systems, such as plants and chloroplasts. Like retinal cells, plant organelles undergo photodamage caused by ROS generation under continuous illumination. We have demonstrated that NC can regeneratively protect plant-extracted chloroplasts from ROS-induced photodamage to prolong extracellular activity for light-harvesting, energy applications. By engineering the polymeric wrapping around the NC particles, we have demonstrated the ability to tune nanoparticle uptake into the plant chloroplast. This platform has been extended to in vivo applications, where single-walled carbon nanotube (SWCNT)-based complexes have been used to monitor and image ROS flux inside intact plant leaves, enabling not only a photonic chemical sensor, but also a novel, nanobionic approach to augmenting photosynthesis and enhancing plant efficiency.

Figure 1
Porphyrin-Fullerene Based Donor-Acceptor Conjugates for Photocontrol of Cell Membrane Potentials
Authors: Takano Yuta , Numata Tomohiro , Fujishima Kazuto , Murakami Tatsuya , Kengaku Mineko , Mori Yasuo , Imahori Hiroshi
Published: February 2020

Optical control of cellular functions is a promising approach for therapeutic application because it can realize precise control with resolutions of submicrosecond temporally and submicrometer spatially.1 Among various key factors for controlling cellular functions, cell membrane potential is one of the most important ones because it triggers various biological events such as neuron fire and cell signaling. For maintaining membrane potentials, ion channels play crucial roles to keep or to change cell membrane potentials. Therefore, artificial control of cell membrane potential and selective inhibition/activation of ion channels are considered to be promising therapeutic approach.2

   Meanwhile, in electron donor-acceptor linked molecules, photoirradiation triggers intramolecular electron transfer and then charge separated (CS) state is generated. The molecules in CS state demonstrate high oxidizing and reducing abilities, and may induce large dipole which can generate large electric field in nanometer scale. Our group has focused on the photoinduced CS states in the donor-acceptor linked molecules because it may perturb an environment in the cell membrane and may influence function of the proteins therein. Recently, we have reported that such molecules can induce depolarization in the membrane potential of PC12 cells as well as inhibition of the potassium ion flow across the membrane by illumination.3

   In this study, a series of amphiphilic electron donor-acceptor linked molecules based on fullerene and porphyrin were systematically designed, synthesized and investigated for photocontrol on cell membrane potentials. Their molecular structures and unique aggregate structures revealed their characteristic photoinduced excited states of the molecules. Utilizing fullerene moiety was found to be a key for formation of the unique aggregates in highly polar solvent and introduction of porphyrin moiety provides a benefit for using light energy efficiently. Successful design of a CS molecule was found to suppress photocytotoxicity of the molecule remarkably and demonstrated its ability for modulation on the membrane potentials which can increase the frequency of the action potential and trigger neuron firing in rat hippocampal neurons by photo irradiation.

References:

[1] (For a review) Briele, C. et al. Angew. Chem. Int. Ed.
2012, 51, 8446.

[2] (For a review) Wulff, H. et al. Nat. Rev.
2009, 8, 982.

[3] Takano, Y. et al. J. Am. Chem. Soc.
2012, 134, 6092.

Figure 1
Playing with Fullerene, Carbon Nanotubes, Nanodiamonds and Other Carbon Nanostructures
Authors: DaRos Tatiana , Armuzza Valentina , Gonzalez Dominguez Jose Miguel , Gajewska Agnieszka , Carini Marco
Published: February 2020

In the last 20sh years the Carbon Nanostructures’ family grew and attract the attention of many researchers working in different fields. Many efforts in the studies of functionalization have been done, especially struggling with the necessity of an easy way to manipulate these structures. Solubility and orthogonal multiple functionalization are the main goals to be achieved when these materials have to be used for biological applications, as oligonucleotides vector, potential antiviral derivatives, or gene expression modulators.

In this communication, an overview of the recent achievements will be presented.

Figure 1