Highlights

Abstract

Graphical abstract

Keywords

1. Introduction

2. Apparatus

3. Buffer gas cooling considerations

3.1. Buffer gas cell & pumping requirements

3.2. Diffusion and cooling times

3.3. Buffer gas loading of sublimed molecules

4. Spectrometer sensitivity

5. Conclusion

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgements

References

Abstract

High temperatures and associated poor rotational partition functions have hindered the application of high-resolution rotational spectroscopy for detection of molecules desorbing from an ice substrate. Here, an experimental approach is presented which will enable such investigations through incorporation of a buffer gas cooling cell. We discuss design considerations for this apparatus and the expected performance based upon OC34S measurements made with a related spectrometer in a 14.7 K sampled uniform flow. We highlight specific applications of this technique including chiral sensing of molecules generated in an interstellar ice, and the synthesis of exotic species not amenable to generation in the gas-phase.

I. Introduction

Chemistry taking place in ices profoundly impacts atmospheric chemistry and chemistry in astrochemical environments[1,2]. For example, the synthesis of prebiotic amino acids and sugars, as well as the enantiomeric excess observed on Earth may be attributed to chemistry that took place in ice[3,4]. However, current laboratory studies mainly employ mass spectrometric and Fourier-transform infrared spectroscopic detection and do not take advantage of recent tremendous advances of broadband rotational spectroscopy[5,6]. This is largely because of the disadvantage of the rotational partition function associated with molecules desorbing from these ices at typical temperatures from 80-200 K. A means to cool these molecules offers the advantage of rotational spectroscopy for effective probes of chirality, isomer-specificity, complex mixture analysis, and meaningful relative intensities for product branching ratios. There have been, to our knowledge, two reports on the application of millimeter and submillimeter spectroscopy applied to study interstellar ice chemistry. Widicus-Weaver et al. demonstrated the first such experiments in their detection of thermally desorbed H2O, D2O, and CH3OH originating in a solid film created at ~ 12K[7].

Highlights

Abstract

Graphical abstract

Keywords

1. Introduction

2. Apparatus

3. Buffer gas cooling considerations

3.1. Buffer gas cell & pumping requirements

3.2. Diffusion and cooling times

3.3. Buffer gas loading of sublimed molecules

4. Spectrometer sensitivity

5. Conclusion

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgements

References

Abstract

High temperatures and associated poor rotational partition functions have hindered the application of high-resolution rotational spectroscopy for detection of molecules desorbing from an ice substrate. Here, an experimental approach is presented which will enable such investigations through incorporation of a buffer gas cooling cell. We discuss design considerations for this apparatus and the expected performance based upon OC34S measurements made with a related spectrometer in a 14.7 K sampled uniform flow. We highlight specific applications of this technique including chiral sensing of molecules generated in an interstellar ice, and the synthesis of exotic species not amenable to generation in the gas-phase.

I. Introduction

Chemistry taking place in ices profoundly impacts atmospheric chemistry and chemistry in astrochemical environments[1,2]. For example, the synthesis of prebiotic amino acids and sugars, as well as the enantiomeric excess observed on Earth may be attributed to chemistry that took place in ice[3,4]. However, current laboratory studies mainly employ mass spectrometric and Fourier-transform infrared spectroscopic detection and do not take advantage of recent tremendous advances of broadband rotational spectroscopy[5,6]. This is largely because of the disadvantage of the rotational partition function associated with molecules desorbing from these ices at typical temperatures from 80-200 K. A means to cool these molecules offers the advantage of rotational spectroscopy for effective probes of chirality, isomer-specificity, complex mixture analysis, and meaningful relative intensities for product branching ratios. There have been, to our knowledge, two reports on the application of millimeter and submillimeter spectroscopy applied to study interstellar ice chemistry. Widicus-Weaver et al. demonstrated the first such experiments in their detection of thermally desorbed H2O, D2O, and CH3OH originating in a solid film created at ~ 12K[7].

Introduction

Materials and Methods

Results and Discussion

Conclusions

References

ABSTRACT

RNA molecules perform a variety of biological functions for which the correct three-dimensional structure is essential, including as ribozymes where they catalyze chemical reactions. Metal ions, especially Mg2þ, neutralize these negatively charged nucleic acids and specifically stabilize RNA tertiary structures as well as impact the folding landscape of RNAs as they assume their tertiary structures. Specific binding sites of Mg2þ in folded conformations of RNA have been studied extensively; however, the full range of interactions of the ion with compact intermediates and unfolded states of RNA is challenging to investigate, and the atomic details of the mechanism by which the ion facilitates tertiary structure formation is not fully known. Here, umbrella sampling combined with oscillating chemical potential Grand Canonical Monte Carlo/molecular dynamics simulations are used to capture the energetics and atomic-level details of Mg2þ-RNA interactions that occur along an unfolding pathway of the Twister ribozyme. The free energy profiles reveal stabilization of partially unfolded states by Mg2þ, as observed in unfolding experiments, with this stabilization being due to increased sampling of simultaneous interactions of Mg2þ with two or more nonsequential phosphate groups. Notably, these results indicate a push-pull mechanism in which the Mg2þ-RNA interactions actually lead to destabilization of specific nonsequential phosphate-phosphate interactions (i.e., pushed apart), whereas other interactions are stabilized (i.e., pulled together), a balance that stabilizes unfolded states and facilitates the folding of Twister, including the formation of hydrogen bonds associated with the tertiary structure. This study establishes a better understanding of how Mg2þ-ion interactions contribute to RNA structural properties and stability.

INTRODUCTION

RNA molecules have highly diverse structures ranging from simple helices to highly heterogeneous folded conformations that are essential for their wide range of cellular functions (1–3). Specifically, ribozymes, a distinct class of enzymes, exhibit complex tertiary structures and catalyze self-cleavage or the cleavage of phosphodiester bonds of substrate RNA, with metal ions typically playing a central role in the catalytic activity (4–6). To assume their tertiary structures, RNAs must overcome large unfavorable electrostatic interactions associated with their polyanionic phosphodiester backbone (7). To facilitate this, positively charged ions screen the highly negative potential, allowing the RNA secondary structures to collapse into compact tertiary conformations (8–11). Typically divalent ions, most often Mg2þ, facilitate the formation of tertiary interactions required for the full folding of RNA (12–14). However, the inability to visualize the ions during folding represents a key barrier to understanding the role of divalent ions in folding of RNA (15). Studies have used classical molecular dynamics (MD) or other theoretical approaches to investigate Mg2þ-RNA binding, but they were limited to native conformations because of their inability to overcome the issues associated with the Mg2þ exchange rates (16–22). The exchange rate of water complexed to Mg2þ is on the ms timescale (6.7 105 s 1 ), and the exchange rate of Mg2þ with phosphate is on the ms timescale (0.5–2.5 103 s 1 ) (23), which is beyond the timescale of typical atomistic MD simulations (20,24) such that only limited insights into Mg2þ-RNA interactions are accessible (25). Alternatively, simulations using coarse-grained models of nucleic acids provided insights into how Mg2þ can serve to nucleate the folding of key tertiary interactions with the Mg2þ-RNA interactions being dominated by specific interactions even in unfolded states (19,26).

1- Introduction

2- Calculation details

3- Results and discussion

4- Conclusion

References

Abstract

High spin-polarized materials are expected for the development of spintronic devices. In this work, we are aiming to find new spintronic materials in Mn-based binary, ternary and quaternary Heusler alloys by using the first-principles calculations. We investigated structures, electronic properties, magnetic, tetragonal distortion and mechanic properties of Mn3Ga, Mn2YGa (Y = V, Nb, Ta) and ScMnVGa. The results show that Mn3Ga, ScMnVGa type-I, and type-II have lower energy in antiferromagnetic (AFM) states than ferromagnetic (FM) and paramagnetic (NM). Mn2YGa (Y = V, Nb, Ta) compounds are more stable in FM states. The results of electronic and magnetic properties indicate that Mn3Ga is a gapless half-metallic antiferromagnet (Gapless HM-AFM). Mn2VGa and Mn2NbGa belong to gapless half-metallic ferrimagnets (Gapless HM-FE). Mn2TaGa is ferrimagnets. ScMnVGa type-I is half-metallic antiferromagnets (HM-AFM) and type-II belongs to spin gapless semiconductors with AFM (SGSs-AFM). Inspired by Ferromagnetic shape memory alloys (FAMAs), we performed tetragonal deformation of those compounds, and we predicted that Mn3Ga, Mn2YGa (Y = V, Nb, Ta) have possible martensitic transformations. Finally, the mechanical stability and elastic properties of above-mentioned in both cubic and tetragonal structures were discussed in detail.

Introduction

Spintronics is considered to be one of the most promising subjects in the information age because spintronic devices use not only the state of charge but electronic spin to transfer and store information, which speeds up information transmission and reduces energy losses. The findings of Giant Magnetoresistance (GMR), Colossal Magnetoresistance (CMR) and Tunnel Magnetoresistance (MGR) accelerate the development of spintronics. Despite great potential advantages, spintronics still faces some challenges, such as, generate high spin injectors. However, the discovery of half-metallic ferrimagnet has improved this problem, which is an ideal semiconductor spin-injection source due to it has 100% spin polarizability. Among different halfmetallic materials, Heusler alloys are prominent especially owing to high Curie temperature and flexible electronic structures [1,2]. Since De Groot et al. [3] discovered the half-metallic ferromagnets of NiMnSb, while they were calculating the energy band using the planewave method, this intermetallic materials with unusual electronic structures arouse people’s attention. In the big family of Heusler alloys, Co-based Heusler alloys [4–6] usually show magnetism, and the source of this property is direct interaction between Co-Co atoms. Cu-based Heusler alloys [7–9] are typical representative of non-magnetic elements show ferromagnetic after high-ordered, Pd-based Heusler alloys [10,11] which contain rareearth elements is superconducting, Ni2Mn-based Heusler alloys [12–17] have both ferromagnetic properties and thermoelastic martensitic transformation, which realizing magnetic-field-induced strain, shape memory effect, magnetoresistance effect and other application functions. At present, most research focuses on ternary Mn-based Heusler alloys, and they usually behave ferromagnetic or ferromagnetic [18–21]. Actually, besides half-metallic ferromagnets and ferrimagnets, half-metallic antiferromagnets also worthy of study. Not only it has 100% spin polarizability, but its total magnetic moment is zero. Thus, it means that when HM-AFMs are applied to spintronic devices, and those alloys will get the feature of the low-stray field and low energy loss. HM-AFMs were discovered in Heusler alloys [22] and perovskite compounds [23]. Besides, the martensitic transformation was found in some Mn-based Heusler alloys [24–26].

Owing to the low cost, abundance and high working voltage, graphite cathodes have attracted tremendous attention in rechargeable batteries, especially in aluminum ion batteries (AIBs) and dual-ion batteries (DIBs). In this review, firstly, a general introduction is given to distinguish the working mechanism of graphite from the conventional metal oxide used as cathode in batteries. Secondly, the characterization methods of anion intercalated compounds, theoretical simulation of anion intercalation behavior into the graphitic cathode and the kinetic study of anion diffusion in graphite are discussed. Then, progresses and challenges of AIBs with different types of graphite cathode materials are presented. Next, typical DIBs systems with graphite cathode, a variety of anodes and electrolytes are introduced in detail. Finally, a conclusion for battery systems with anion intercalation graphite cathodes is draw, and a perspective is outlined to address the existing technical barriers that need to be overcome in future research direction.

Introduction

Background

A rechargeable battery is an electrochemical device that can store electrical energy as chemical energy in its anode and cathode during the charging process, and releases the energy as electrical output during the discharging process [1-3]. An ideal rechargeable battery is expected to have high energy density, high power density, long cycle life, excellent environmental compatibility and low cost [4-15]. Metal ion batteries (MIBs), including lithium ion batteries (LIBs), sodium ion batteries (SIBs) and potassium ion batteries (PIBs) et al. are typical rechargeable batteries, which rely on the metal ions shuttling between the anode and cathode to realize charging and discharging. Among them, LIBs, which possess the merits of long cycle life, high energy and power density and no memory effect, have dominated the battery market of portable electronics and electric vehicles for around two decades and are as well widely used in grid-scale energy storage [5, 16-20]. Despite currently enormous successes in portable electronics and electric vehicles (EVs), LIBs are limited in meeting the growing demand for higher energy and power densities [21-40]. In another aspect, LIBs are plagued by the shortage and high cost of resource metals (Li, Co, Ni etc.) needed in the battery manufacture, and the corresponding environmental pollution of abandoned batteries [17, 41, 42]. Therefore, searching for novel electrode materials, especially cathode materials that of resource-abundant and easily recyclable properties, is in great demand [1]. Graphite is a unique layered structure composed of graphene layers stacked together by the van der Waals force. Since its interlayer space are highly tunable, graphite can accommodate a variety of ions and molecules to form graphite intercalation compounds (GICs), which display applications in electrical, electrochemical and chemical industries because of their unique physicochemical properties. For instance, the reversible intercalation/de-intercalation of metal ions (Li+ , Na+ and K+ et al.) into/from the graphite makes it widely used as anodes for MIBs. Although comparatively less developed, graphite, which have also exhibited the reversible intercalation and de-intercalation of anions such as hexafluorophosphate anion (PF6 – ), bis(trifluoromethanesulfonyl)imide anion (TFSI- ) [43-48], is becoming a promising cathode materials in dual-ion batteries (DIBs), hybrid electrochemical capacitors (ECs) [49, 50] and aluminum ion batteries (AIBs). Among these, DIBs and AIBs are gaining more attention since they have obvious advantages over conventional MIBs: 1) lower cost and resource abundance compared to conventional metal oxide cathode in MIBs; 2) higher voltage, which benefits for a higher energy density [51, 52].

1- Introduction

2- Experimental methods

3- Results and discussion

4- Conclusions

References

Abstract

Cu2O-CuO layers were prepared in situ on copper foam substrates by thermal oxidation at 400 °C in air using different pretreatments with acetone, HCl and NaOH. The effect of the pretreatment in the shape and physicochemical properties of the Cu2O-CuO layers, as well as in the growth or inhibition of the copper oxide nanostructures was studied, and a growth mechanism is proposed. It was found that the pretreatment modulates the nucleation and growth of the copper oxide nanostructures, being the process with NaOH the most suitable to promote the formation of well-defined nanoneedles, while in the case of the samples pretreated with acetone and HCl, copper oxide layers with irregular shape microstructures were obtained. The composition, structural, morphological and optical properties of the copper oxide structures were determined by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance and photoluminescence spectroscopy. The results showed that in all cases, the presence of both copper oxides, Cu2O and CuO was observed, with an optical band gap of 1.0 and 1.3 eV. The copper oxide structures exhibited photoluminescence emission centered at 551 nm, related to the recombination of the electron-hole pairs in the samples. The materials prepared with a NaOH pretreatment showed the lower emission and recombination rate.
Moreover, the 3D Cu-Cu2O-CuO based materials were evaluated as photocathodes in a 0.5 M Na2SO4 solution and under Xe lamp illumination. The photoelectrode where 1D nanostructures were grown, exhibited the lower resistance to the charge transference in the Nyquist plots, the highest current density in the linear voltammetry and the highest photoresponse in the on-off light experiments. The improved electrical and physicochemical properties of the samples pretreated with NaOH was related to the particular 1D nanoneedle morphology, which promoted higher conductivity and photoresponse, lower resistance to the charge transference and lower recombination of free charge carriers, demonstrating the potential use of these electrodes for photoelectrochemical applications. Finally, this work proved that it is possible to grow well-defined and highly crystalline CuO nanoneedles on copper foam porous substrates through a simple, fast and clean method.

Introduction

1D nanostructured copper oxides have attracted attention recently due to their potential use in several applications such as cathodes for lithium-ion batteries [1,2], gas sensors [3] and biosensors [4,5], catalysts [6] and photocatalysts [7], as well as photocathodes for hydrogen generation from water [8,9], since cuprous and cupric oxides are usually p-type semiconductors, with a direct band gap of approximately 2.0–2.5 eV and 1.3–1.7 eV, respectively [10]. Moreover, these nanostructures are obtained from copper, an earth-abundant metal, and can be synthesized through facile and scalable methods such as simple thermal oxidation of the copper substrate [3,7,11]. Typically, copper oxide structures in the form of nanowires or nanoneedles are grown on copper substrates by thermal annealing at temperatures between 400 °C and 600 °C in air or oxygen atmospheres [12]. CuO wires, sheets and flower nanostructures have been grown on copper foam substrates and studied as supercapacitors [13], while in other work, highly porous CuO structures for batteries and fuel cells were sculptured tunning the pore sizes through the variation of the deposition conditions [14]. The scalable and facile anodization-calcination process was used also for the preparation of copper oxide anodes for ion-lithium batteries [15]. Moreover, the copper-based nanostructures prepared by this method have exhibited high selectivity, sensitivity and stability for gas sensing applications [16]. The shape of the nanostructures has been also modified through the use of surfactants, such as Triton X-100, for obtaining cabbage rose CuO structures on copper foam substrates [17], and core-shell CuO-NiO hybrid structures with enhanced supercapacitance performance have been prepared [18].

Introduction

Experimental

Results and discussion

Conclusion

References

Abstract

There are proliferation issues with the Plutonium Uranium Redox Extraction process due to the possibility of recovering plutonium. The objective of this research was to evaluate diferent organic extraction ligands that can remove uranium from the nuclear waste and to determine the most efective organic solvent for extracting uranium only, from alkaline media. The results indicate that Alamine 336 in xylene has zero (0%) extraction capability for surrogate fssion products at an optimum extraction time of 15 min. Aliquat 336 in xylene has an extraction percentage of 72% for uranium in 60 min. However, Aliquat 336 in toluene extracted 82% of the uranium from the feed solution after 30 min, decreasing to 76% after 60 min.

Introduction

A large amount of uranium in the environment is caused by human activities such as mining and milling of other minerals and also from operations of reactors, reprocessing of spent nuclear fuel (SNF) and its disposal [1, 2]. It is also of great commercial interest due to its application in the nuclear industry especially in the use and development of new radiopharmaceuticals and radioisotopes [3]. The uranium waste contains insoluble precipitates formed when the target plates uranium–aluminum alloy are dissolved during the production of Mo-99 [4]. The remaining insoluble residue contains about 90% of enriched uranium that is present in the mixture of various oxidation states. A process of ammonium carbonate-based dissolution has been developed for uranium recovery from the waste generated by an alkaline dissolution process used for the production of the medical isotope Mo-99 [5]. Uranium recovery from residue was achieved with three successive ammonium carbonate–peroxide leaches with fnal decontamination factors from low values of 1–10 Cs-137, Ru-106, and Sb-125 to infnity.

1. Overview

2. Properties of CFRP

3. Current Status of CFRP Application in Rail Transit Equipment

4. Principle of electromagnetic shielding

5. Simulation Research

6. Conclusion

7. References

The carbon fiber composite materials have been widely used in the field of rail transit.Carbon fiber body is more advantageous than traditional material especially in weight.This paper introduces main characteristics of carbon fiber composites and outlines the principles of electromagnetic shielding effectiveness.Electromagnetic shielding characteristics of carbon fiber reinforced polymer (CFRP) was studied through electromagnetic shielding simulation technology and test compared with aluminum, aluminum alloy and carbon steel. Some suggestions are provided in terms of the CFRP electromagnetic characteristics. This research sets a foundation for the EMC design for railway vehicles.

Overview

Modern railway vehicles have undertaken improvement and optimization in the aspects of rail transit, intelligence, safety and comfort, especially the high-speed EMU trains. However, speed increase will not only rely on the design of powerful traction system but also on the lightweight design which plays a vital role in this aspect.For the weight, stainless steel is better than weatherproof steel. Aluminum alloy is better than stainless steel. However, carbon fiber reinforced composite has better advantages over aluminum alloy. The application of composites in the high-speed railway vehicles has been gradually enlarged from carbody interior, components and materials of equipment inside vehicles to the carbody structure. Carbon fiber composite will bring rail transit industry into a new stage[1]-[2]. Although CFRP presents excellent properties in various aspects, there are still more aspects of carbody materials to be satisfied for high-speed trains, such as fire performance, thermal insulation properties, corrosion resistance characteristic and electromagnetic properties. Upon comparison with previous car bodies made from steel and aluminum alloy, however less attention is paid to electromagnetic shielding properties of CFRP vehicles.

1- Introduction

2- Experimental

3- Results and discussion

4- Conclusion

References

Abstract

A new cathode material, K2V3O8, is reported reports as a new active material for potassium storage. The K2V3O8 is stabilized into tetragonal structure with P4bm space group, and we verify the unique crystal structure that is coordinated with four hendecahedra of KO11, VO5, and VO4, in which one VO5 shares its four oxygens with four VO4 tetrahedra to produce four penta-shaped voids that allows insertion and extraction of potassium ions. The K2V3O8 modified with carbon exhibits a reversible capacity of 75 mAh (g-oxide)−1, and its electrochemical activity originates from the reversible de-/intercalation of potassium ions into/out of the hendecahedrally coordinated K2V3O8–carbon composite cathode, accompanied by a reversible V5+/4+ redox pair, which is retained for 200 cycles with 80% retention of its initial capacity.

Introduction

Various potassium insertion materials have been introduced and evaluated for their electrochemical performance as cathodes in potassium-ion batteries (KIBs) [1–4]. K-deficient P2- and P3-type KxMO2 (x � 0.7, M ¼ transition metal) layered oxides have been extensively investigated as analogues of sodium-ion batteries (SIBs) [5–12]. They exhibit good electrode performances in terms of specific capacities, although they suffer from detrimental phase transitions resulting from the insertion (and extraction) of the large Kþ ions (1.38 Å) into (and out of) the crystal structure, which, in turn, limit their cycling stability. Vanadium vanadates including oxides have been extensively investigated as cathode materials for rechargeable batteries activated by monovalent and divalent charge carriers (Li, Na, K and Zn ions) because of their diverse structures and outstanding electrochemical activities resulting from the multiple valence states of vanadium [13–16]. Recently, Lu et al. introduced K2V3O8 as an anode material for KIBs [17], presumably activated by conversion process. This unique K2V3O8 structure, arranged with alternating K–O layers and V–O layers along the c-axis, inspires us to adopt it as a cathode material for KIBs. It is thought that de-/intercalation of potassium ions into/out of this crystal structure is possible because hendecahedrally coordinated Kþ-ion layers are located between the edge-sharing VO5 and VO4 assemblies along the c-axis. In this study, we firstly introduce the physical and electrochemical properties of K2V3O8. Due to its poor electrical conductivity, the active material, K2V3O8, is modified by electro-conducting carbon (K2V3O8/C) (Fig. 1a). As per designated, this treatment increases the resulting electrical conductivity to 10 4 S cm 1 at 25 �C, which enables the present K2V3O8 active for Kþ extraction and insertion for 200 cycles, delivering a reversible capacity of 75 mAh (goxide) 1 .

1- Introduction

2- Experimental

3- Results and discussion

4- Conclusions

References

ABSTRACT

Organic-based electrode materials for lithium-ion batteries (LIBs) are promising due to their high theoretical capacity, structure versatility and environmental benignity. However, the poor intrinsic electric conductivity of most polymers results in slow reaction kinetics and hinders their application as electrode materials for LIBs. A binder-free self-supporting organic electrode with excellent redox kinetics is herein demonstrated via in situ polymerization of a uniform thin polyimide (PI) layer on a porous and highly conductive carbonized nanofiber (CNF) framework. The PI active material in the porous PI@CNF film has large physical contact area with both the CNF and the electrolyte thus obtains superior electronic and ionic conduction. As a result, the PI@CNF cathode exhibits a discharge capacity of 170 mAh·g−1 at 1 C (175 mA·g−1 ), remarkable rate-performance (70.5% of 0.5 C capacity can be obtained at a 100 C discharge rate), and superior cycling stability with 81.3% capacity retention after 1,000 cycles at 1 C. Last but not least, a four-electron transfer redox process of the PI polymer was realized for the first time thanks to the excellent redox kinetics of the PI@CNF electrode, showing a discharge capacity exceeding 300 mAh·g−1 at a current of 175 mA·g−1 .

Introduction

Lithium-ion batteries (LIBs) have played an essential role on energy storage for portable electronic devices in recent decades. However, the ever-growing energy storage demands, especially those driven by electrical vehicles and grid-scale storage of renewable electricity, have generated a great concern not only over the energy density and power density, but also the safety, cost, and sustainability of LIBs [1, 2]. Considering the elaborate preparation process, limited resource and environmental and safety issues of the conventional inorganic battery electrode materials, organic materials are intriguing alternatives for sustainable batteries [3, 4] because of the potentially low-cost, high safety, recyclablility, design diversity of molecular structures, and high theoretical capacities due to low formula weight and capability of multiple electron transfer [5–8]. The development of organic compounds as electrode material actually started as early as that of the inorganic materials [9], but the progress is lagging behind due to the tremendous success of inorganic intercalation compounds in the late 1980’s [10]. The main problem of most organic materials is their electronic insulating nature. This means that a large amount of conductive carbon (usually more than 30 wt.%) is normally required for the preparation of an organic electrode using the typical slurry coating method [11]. When the mass of the conductive carbon, the polymer binder and the Al current collector is considered, the practical energy density of organic electrodes is quite low [7]. Besides, uniform distribution and good physical contact of organic active materials and the conductive additive in the electrode is often difficult to achieve with the slurry coating method, resulting in low utilization of the active material and poor rate performance [12]. Polyimide (PI), an important engineering plastic with excellent mechanical strength and outstanding thermal stability, belongs to the category of organic carbonyl compounds, which bear high theoretical capacity for storage of lithium ion [13, 14]. Li ions reversibly that absorb or desorb on oxygen atoms as the carbonyl groups are reduced or oxidized [15]. This process is also known as enolation [15, 16]. Theoretically, PI polymers with 1 mole of repeating units can react to 4 moles of Li ions, resulting in a theoretical capacity of ~ 400 mAh·g−1. However, redox processes beyond two-electron transfer reaction have not been reported for PI electrodes in LIBs. It was predicated that four-electron redox process is nearly impossible to be realized reversibly because deep enolation would damage the molecular structure of PI materials [12, 15]. Furthermore, reaction kinetics of PI electrodes needs to be improved for practical considerations [17].

I- Introduction

II- Device Structure

III- Results And Discussions

IV- Conclusion

References

Abstract

In this work, we have proposed a charge plasma based doping less double gated tunnel FET (DLDGTFET) based biosensor using dielectric modulation with a cavity introduced at the source side for the label free sensing of the biomolecules. These biomolecules are immobilized in the cavity region to induce drain current. The sensing of the biomolecules is based on the drain current of the device while the drain current is based on the dielectric constant and the interfacing charges of the biomolecules. The cavity length is varied between 25 nm and 30 nm and different dielectric constants have been used. The expansion of the cavity length results in slight reduction of the drain current due to lowering of the capacitance. Higher dielectric constants result in better drain current values which leads to an increase in the sensitivity of the device. The maximum sensitivity attained was as high as 1.0×1010. As compared to other transistors, DLDGTFET provides better sensitivity as a biosensor and also the leakage current is low.

INTRODUCTION

LATELY, the field of biosensors has been growing due to its wide range of applications ranging from medical [1] to environmental and agricultural fields. Biosensors based on FETs have been studied due to their various advantages such as low cost and their ability to detect charged biomolecules. FET-based biosensors were popular due to their performance in label-free detection of the biomolecules [2]. Despite being a low cost device, FET based biosensor did not had much applications due to their inability of detecting neutral charged particles. Later on, the dielectrically modulated FET based biosensors were imported to detect both charged and noncharged biomolecules [3]. A cavity was introduced under the gate to immobilize the biomolecules and determine the outcome on the basis of dielectric constant and drain current [4]. The immobilization of the biomolecules causes the electrical parameters to modulate and form a biosensor. However, it has some drawbacks such as scaling, power supply, short channel effects (SCEs) [5, 6], etc.

20-1- Introduction

20-2- Membrane Transport Models

20-3- Concluding Remarks

References

INTRODUCTION

The seawater or brackish water desalination process by reverse osmosis (RO) has been known for many years. Loeb and Sourirajan (1962) developed a method for making asymmetric cellulose acetate membranes, which provide excellent scope for the application of this process for practical purposes due to their relatively high water fluxes and separation efficiency (Williams, 2003). Among the synthetic polymeric membranes on the market is the aromatic polyamide with pendant sulfonic acid group proposed by DuPont (Uemura and Henmi, 2008). It has a high rejection performance, which can be used for single-stage seawater or brackish water desalination. The development of new-generation membranes such as thin-film, composite (with an in situ monomer condensation method), nanostructure, and mixed matrix membranes that can have much higher water flux and solute separation properties has resulted in many additional RO applications such as wastewater treatment, e.g., in the galvanic industry, for water softening, and for food and beverage processing (Bhattacharyya and Williams, 1992). Nowadays, there are growing activities in developing RO membranes from inorganic materials such as ceramic membranes (e.g., a-alumina supported MFI-type zeolite membranes) due to their thermal, mechanical, and chemical properties. Zeolite membranes could be an alternative for polymeric membranes in treating various kinds of water and wastewater, and/or for the separation of organic mixtures (Lee et al., 2011). One of the most important applications of RO is water treatment for producing high-quality water using high-salinity geothermal water, surface water, peat water (natural brown water), as well as wastewater (industrial, municipal water) treatment. RO is capable of removing low concentration bioactive pollutants such as pesticides and hormones from surface water (Hofman et al., 1997). Potential application of the RO process is the concentration of various fruit juices (orange, apple, pear, grape, tomato juices) and preconcentration of sugar juices. This process is also widely applied in the dairy industry for, e.g., recovering protein, defatting whey, and concentrating milk and whey as alternatives to conventional processes (Pouliot, 2008). Other applications of the RO process are, e.g., alcohol removal from fermented beverages and separation of organic mixtures, including alcohols and hydrocarbon (azeotropic, isomeric) mixtures (Koops et al., 2001). Fouling/biofouling is regarded as the most serious problem in the RO process, depending on the water composition used for separation. Reasons for fouling of the RO membrane are chemical (adsorption of organic materials) and biological fouling (microbe adsorption by hydrophobic or electrostatic interaction, deposition of exhaust material of biological metabolism) (Uemura and Henmi, 2008). This is why it is important to produce a low-fouling property membrane with high water flux and stable operation.