Fold Enhancement Research Articles

Contribution of O2 plasma treatment and amine modified GOs on film properties of conductive PEDOT:PSS: Application in indium tin oxide free solution processed blue OLED

Primary (n-propyl amine, n-PRYLA), secondary (dipropyl amine, DPRYLA) and alcohol (propanol amine, PRPOHA) amine derivatives were used as amine sources in graphene oxide (GO) modification and obtained samples were named as nPRYLA-GO, DPRYLA-GO and PRPOHA-GO, respectively. Modified graphene oxide (mGO) derivatives were doped in poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PH1000) and O2 plasma treatment (70W, 3 min) was applied on the spin casted films. PH1000:mGO films presented high optical transparency values (>90%) and low resistivity (177–183 Ω/sq). The roughness values were increased especially when the hydrophobic alkyl chain containing DPRYLA-GO and nPRYLA-GO were doped in PH1000. Prepared films were utilized as anode in solution processed blue organic light emitting diode. PH1000:PRPOHA-GO anode presented more than 30 nm of decrement in full with at half maximum and 1.6, 1.5 and 1.9 fold enhancements in current, power and external quantum efficiency values, compared to those of ITO anode, respectively.

In situ observation of NiS nanoparticles depositing on single TiO2 mesocrystal for enhanced photocatalytic hydrogen evolution activity

For photocatalysis, clarifications of charge carrier migration route and kinetics on individual particles by photoluminescence (PL) are of great importance because they play significant roles on unveiling the precise information of structure-activity relationships and closely relate to the photocatalytic activities of those semiconductors on targeted functions. Here, photodeposition process of NiS nanoparticles on single TiO2 mesocrystal (TMC) as co-catalyst is in situ monitored by PL images and spectra using a confocal single-particle PL microscopy, which provides straightforward results on understanding the photoexcited electrons transfer in both individual TMC and TMC/NiS nanoparticles. Through the changes in PL intensity and decay lifetime, preferential trapping site for NiS nanoparticles on TMC is identified and efficient electron interfacial migration from TMC to NiS nanoparticles is demonstrated, which lead to an almost 71 folds enhancement on the photocatalytic H2 evolution under 365-nm photoirradiation compared to pure TMC particles.

Preparation of luliconazole nanocrystals loaded hydrogel for improvement of dissolution and antifungal activity

Superficial fungal infection in immunocompromised patients can lead to many disorders and complications. Currently, new topical treatment options are critically needed to treat these fungal infections. Luliconazole (LZL) is a topical antifungal medicine used for fungal infection treatment. The purpose of this paper was to develop a new topical luliconazole nanocrystal (LNC) incorporated hydrogel. This study suggested the potential benefits of LNC embedded in a gel as a drug delivery system for topical antifungal treatments. Preliminary experiments were therefore carried out to characterize the LNC in comparison with raw drug. Prepared gel was homogeneous for human use with about 88 percent trapping, non-irritant and safe. Nano-systems showed an overall 5 fold enhancement in solubility, 4 fold increase in dissolution velocity, higher skin retention and better antifungal activity. Drugs retained from LNC hydrogel (N-GEL) in different skin layers within 8 h were the highest, i.e. 62.17% compared to coarse suspension (41.87%), nanosuspension (49.77%), D-GEL (55.76%). In addition, LNC and N-GEL had higher ZOI (41.20 ± 0.61mm and 44.25 ± 0.57mm respectively) than LZL and D-GEL (35.98 ± 0.81mm and 36.83 ± 0.83mm respectively). Therefore, it was observed that LNC loaded hydrogel was more effective in killing the fungus. Consequently, hydrogel incorporated with LNC could be a new approach with improved activity and increased dermal delivery for drugs with poor aqueous solubility rather than coarse drug containing gel.

(Invited) sp3 Defects of Single Walled Carbon Nanotubes: Photonic and Electronic Integration

Single walled carbon nanotubes with covalently functionalized sp3 defects have been rapidly emerging as a new class of transformational optical materials. Particularly, recent demonstration of room temperature, 1.55 µm single photon generation establish these covalent defects of SWCNTs as promising fundamental building blocks for defect driven quantum information technologies such as quantum key distribution. Defects also provide a significant boost in photoluminescence quantum yield (from <1% to ~28%) and emission stability, making envisioned applications of SWCNTs in optoelectronics, sensing, and imaging technologies more feasible. The key to full exploitation of these technological potentials lie in the ability to integrate these SWCNTs with defects into plasmonic/photonic cavities for enhancement of light matter interactions and into nano-electronic devices for electrical stimulation. Here in this talk I will report recent progresses we made together with our collaborators toward achieving this critical photonic and electronic integration. We have successfully integrated the SWCNTs with sp3 defects into 2D slab photonic crystals1 and metallo-dielectric antenna arrays.2 In case of coupling with 2D photonic crystal, we were able to demonstrate room temperature single photon generation with 3meV linewidth defined by the cavity quality factor and 50 fold enhancement in emission.1 We achieved narrowest low temperature emission linewidth of 35 µeV by coupling the defects with metallo-dielectric antennas.2 We were also successful in fabricating single SWCNT field effect transistors using dielectrophoresis and attained electroluminescence from the sp3 defects. Ishii, A.; He, X.; Hartmann, N. F.; Machiya, H.; Htoon, H.; Doorn, S. K.; Kato, Y. K. Enhanced Single-Photon Emission from Carbon-Nanotube Dopant States Coupled to Silicon Microcavities. Nano Lett. 18 , 3873-3878 (2018).Shayan, K.; He, X.; Luo, Y.; Rabut, C.; Li, X.; Hartmann, N.F.; Blackburn, J.L.; Doorn, S.K.; Htoon, H.; Strauf, S.; “Suppression of Pump-Induced Exciton Dephasing in Sidewall-Functionalized Single-Walled Carbon Nanotubes”, Nanoscale 10 , 12631 (2018).

Trichoderma-Azotobacter biofilm inoculation improves soil nutrient availability and plant growth in wheat and cotton.

Microbial biofilms are gaining importance in agriculture, due to their multifaceted agronomic benefits and resilience to environmental fluctuations. This study focuses on comparing the influence of single inoculation-Azotobacter chroococcum (Az) or Trichoderma viride (Tv) and their biofilm (Tv-Az), on soil and plant metabolic activities in wheat and cotton grown under Phytotron conditions. Tv-Az proved superior to all the other treatments in terms of better colonisation, plant growth attributes and 10-40% enhanced availability of macronutrients and micronutrients in the soil, over control. Confocal and scanning electron microscopy showed that the cells attached to the root tips initially, followed by their proliferation along the surface of the roots. Soil polysaccharides, proteins and dehydrogenase activity showed several fold enhancement in Tv-Az biofilm inoculated samples. Time course studies revealed that the population of Az and Tv in the rhizoplane and rhizosphere was significantly higher with a 0.14-0.31 log colony-forming unit (CFU) increase in the biofilm-inoculated treatment in both crops. Enhancement in soil biological activities was facilitated by the improved colonisation of the biofilm, due to the synergistic association between Tv and Az. This demonstrates the utility of Tv-Az biofilm as a multifunctional plant growth promoting and soil fertility enhancing option in agriculture.

A novel strategy for markedly enhancing the green upconversion emission in Er3+/Yb3+ co-doped VO2

There is a growing interest in developing upconversion nanocrystals at the forefront of promising applications. However, insufficient energy transfer between lanthanide ions still limited the practical application. In this work, a new class of welded-structure upconversion nanoparticles which emits bright green emission upon 980 nm near-infrared (NIR) laser excitation is presented. Importantly, this unique welded-structure arrangement enables the high-efficient energy transfer between different nanocrystals, leading to 65-folds enhancement for green upconversion emission. A continuous wave 980 nm laser is used to reduce interparticle distance followed by structure welding. The experiment findings show that the controlling distance of nanosheets enables readily manipulation the intensity ration of green and red emission, thereby allowing us to achieve the emission color purity tuning from pea green to bright green. And the green and red ratio achieved 11 folds enhancement, leading to a purer green light emission. The result not only provide an upfront experimental design for constructing welded-nanostructures with efficient energy transfer and color purity tunability, but also suggests a new pathway to build high-efficiency upconversion systems.

Plasmon resonance enhanced WS2 photodetector with ultra-high sensitivity and stability

Tungsten disulfide (WS2) has been demonstrated for optoelectronic devices due to its favorable semiconducting band gaps, high stability and higher carrier mobility than other transition metal dichalcogenides (TMDs). However, the photoresponsivity of WS2-based photodetector is low due to the poor optical absorbance, which limits its application in high-performance photodetection. Here, we show an easy realized method to improve the responsivity of WS2 detectors by Au nanospheres (NPs). The Au NPs concentrate free space electromagnetic wave efficiently by localized surface plasmon resonances (LSPR), strongly enhance the electric field on WS2 films. As a result, more carriers are excited with the assistant of LSPR. With optimized design, the detector exhibited several times to ten folds enhancement from near infrared to visible spectrum region, and reach an excellent high responsivity of 1050 A/W at the wavelength of 590 nm. Furthermore, the photodetector showed an excellent temperature stability after annealing at 300 °C on air environment. The work provides a new way for high-performance and stable photodetector for extreme and harsh environment.

Optoelectrical anisotropy in graphene oxide supported polythiophene thin films fabricated by floating film transfer

A facile method for the fabrication of highly oriented hybrid thin films of conjugated polymer (CP) with graphene oxide (GO) as 2D nano-filler over the high surface tension liquid substrate by floating film transfer is being reported. Formation of the self-assembled oriented hybrid thin film has been validated using multiple characterization techniques. Hybrid thin films thus prepared have been used for the fabrication of organic field effect transistors (OFETs) followed by investigation of anisotropic charge carrier transport. OFETs made with hybrid films oriented in channel direction exhibited the superior device performance with >6 fold augmentation in field effect mobility (μ) and one order improvement in on/off ratio as compared to that of devices based on pristine CP. However, pristine polymer shows 2.2 fold enhancement in mobility and one order augmentation in on/off ratio in parallel orientation as compared to the corresponding perpendicularly oriented films. Thus, our study has elucidated a path to obtain oriented, aligned, and self - assembled hybrid films for further improvement in the device performance aiming towards the applications in organic electronics.

Enhanced sustained release of furosemide in long circulating chitosan-conjugated PLGA nanoparticles.

Furosemide (FSM) is commonly used in the treatment of edema associated with congestive cardiac failure, cirrhosis of the liver, renal disease, including the nephrotic syndrome and hypertension. However, in ascites, it is clinically limited due to its frequent dosing and short biological half-life and its prolonged-release preparations are not available. Therefore, the main objective behind the present research work is to develop chitosan coated and conjugated poly (lactic-co-glycolic acid) (PLGA) nanocarriers, to sustain the delivery of FSM with improved systemic circulation. Emulsion-solvent evaporation technique was used for the preparation of nanoparticles. In-vivo pharmacokinetic study showed 2.6, 3.10, and 4.30 folds enhancement in relative availability of FSM for FSM-PLGA, FSM-chitosan-coated-PLGA and FSM-chitosan-conjugated- PLGA nanoparticles, respectively than FSM. The present research work concluded that FSM loaded chitosan conjugated PLGA nanoparticles could enhance the systemic circulation of FSM with improved pharmacokinetics parameters.

Use of the fluorogenic Al3+–quinolinyl-azo-naphtholato complex for the determination of F− in aqueous medium by visible light excitation and application in ground water fluoride analysis

Quinolinyl-azo-naphthol (HL) is a selective turn-on chemosensor for Al3+ in the presence of other ions and the excitation at visible light (537 nm) shows a 750 fold enhancement of emission at 612 nm.

Micellar catalysed and heteroaromatic base promoted rate enhancement of oxidation of an alicyclic alcohol in aqueous medium

Under pseudo 1st order reaction condition cyclohexanol, an alicyclic alcohol produces cyclohexanone with a moderate rate of oxidation. Promoters and surfactants enhanced the rate of oxidation with chromic acid. The product is confirmed by melting point study; 2, 4 DNP test; IR and NMR study. Among the three micellar catalyst SDS shows higher rate where as phen promoted reaction shows smaller half life. Combination of SDS and bpy shows a 600 fold enhancement in the rate of the reaction. NMR study is also carried out to confirm the interaction between the surfactants and cyclohexanol.

Enhancement of luminescence intensity and spectroscopic analysis of Eu3+ activated and Li+ charge-compensated Bi2O3 nanophosphors for solid-state lighting

The present work reports the synthesis, characterization, photoluminescence and photocatalytic activity of Eu3+ (1 mol%–11 mol%) doped and Li+ (0.5 mol%–5 mol%) co-doped Bi2O3 nanophosphors (NPs) by sonochemical method. The average particle size was estimated using powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) and is found to be in the range of 30–35 nm. The scanning electron microscopy (SEM) images were highly dependent on sonication time and concentration of epigallocatechin gallate (EGCG) bio-surfactant. The energy gap of doped and co-doped Bi2O3 nanophosphors was estimated using Kubelka-Munk (K-M) function and is found to be in the range of 2.9–3.08 eV. The effect of Li+ co-doping on luminescence of optimized Bi2O3:Eu3+ was studied and is found about more than 3 fold enhancement of emission intensity. Judd-Ofelt parameters (Ω2, Ω4 and Ω6), transition probabilities (AT), quantum efficiency (η), luminescence lifetime (τrad), color chromaticity coordinates (CIE) and correlated color temperature (CCT) values were estimated from the emission spectra and are discussed in detail. The estimated CIE chromaticity co-ordinates are very close to the NTSC (National Television Standard Committee) standard value of red emission. The synthesized NPs show excellent photocatalytic activity of acid red-88 under UV-light irradiation, which can degrade 98.1% in 60 min. The decreasing electron–hole pair recombination rate with quick electron transfer ability is predominantly ascribed to the balance between crystallite size, morphology, band gap, defects, surface area, etc. These results show a light for the use of sonochemical route of Bi2O3:Eu3+:Li+ in solid state display and photocatalytic applications.

Enhancement of carbon detection sensitivity in laser induced breakdown spectroscopy with low pressure ambient helium gas

Carbon detection is usually difficult to carry out with high sensitivity and minimally destructive effect. While the conventional laser induced breakdown spectroscopy (LIBS) method operated with atmospheric ambient air is well known as a powerful and versatile analytical tool, it suffers nevertheless from the low sensitivity of C detection when measured in both atmospheric and low pressure ambient air with the more adverse effect found in the former case. This was shown to have its origin in the serious time mismatching effect between the formation of the shock wave plasma by the ablated major host elements and the premature fast passage of the much lighter ablated C atom. However, this study shows the result of high sensitivity C analysis of stone samples using LIBS technique with relatively low laser pulse energy of 60 mJ and low pressure He ambient gas without showing visible surface damage. The helium gas provides the additional delayed excitation by the He metastable excited states through the Penning-like ionization process. The C emission intensities measured from the jasper and black stone in 2.6 kPa He ambient gas are in general significantly higher than those measured in 0.5 kPa ambient air. The enhancement is shown to increase reaching an 8 fold enhancement with increased laser energy up to 60 mJ before undesirable surface damage is created. A further measurement of C emission using pelletized KBr mixtures with various CaCO3 concentrations reveals a straight calibration line of rather large slope with extrapolated zero intercept and estimated detection limit of around 0.6 ppm, demonstrating its potential application for highly sensitive quantitative analysis of C with minimal destructive effect.

A genetically-encoded synthetic self-assembled multienzyme complex of lipase and P450 fatty acid decarboxylase for efficient bioproduction of fatty alkenes

We develop an efficient and economic cascade multienzymes for fatty alkene bioproduction based on the lipase hydrolysis coupled to the P450 decarboxylation in the form of multiple enzyme complex. One step preparation of a multienzyme complex was based on a mixture of cell extracts including dockerin-enzyme fusions and one cohesin-cellulose binding module (CBM) fusion through high specific interaction of dockerin and cohesin. Simultaneously, the CBM was bound to cellulose carrier to form co-immobilized multienzyme. The key factors affecting overall efficiency of alkene bioproduction including substrate channeling of hydrolysis and decarboxylation, the ratio and position of two enzymes, stability were all addressed by genetically engineering of the synthetic CBM-cohesin fusions. The multienzymes exhibited more than 9.2 fold enhancement in initial reaction rate and much higher conversion yields (69%–72%) compared to mixture of free enzyme counterpart. The enzymatic cascade based multienzymes could efficiently convert renewable triglycerides to alkenes.

Conformation Specific Binding of [Ru(phen)2(dppz)]2+ with Mono‐ and Cluster Arylamine‐DNA Adducts

AbstractThe development of any probe to detect cluster adducts requires an in depth understanding on the binding affinity of probes to these adducts. In this context, we attempted to study the interaction of known DNA molecular switch [Ru(phen)2(dppz)]2+ with mono‐ and cluster DNA adducts in 16‐mer NarI sequence (5′‐CTCTCG1G2CG3CCATCAC‐3′) where guanine bases are modified with N‐acetyl‐2‐aminofluorene(AAF). Luminescence studies show that [Ru(phen)2(dppz)]2+ (phen: 1,10‐phenanthroline and dppz: dipyrido[3,2‐a:2′,3′‐c]phenazine) binds to AAF adduct at G1 and G3 which possesses minor‐groove(W) and stacked conformation(S) exhibit two fold enhancement while G2 with major groove B‐conformer exhibit 1.6 fold enhancement when compared to control. In diadducts, RuII binds to G2G3 AAF adduct lower than that of other two diadducts G1G3 and G1G2. With triadducts, phenazine moiety of RuII complex adopts canted geometry to the DNA due to the very unstable structure at the adducted site. From microscale thermophoretic data, the kd of RuII was determined and found to be consistent with luminescence data. The present study provides an overall insight of role of conformation of AAF structure embedded in different sequence context that dictates the sensitivity of the DNA molecular light switch, in turn, facilitates in developing highly efficient probe to distinguish these cluster adducts.

Carbon nanotubes enhance permeability of ultrathin polyamide rejection layers

Membranes with ultrathin rejection layers can effectively achieve high water permeability. In the current study, we report a single-step fabrication of carbon nanotubes (CNTs)-loaded ultrathin film composite (uTFC) polyamide membranes using an electrospray-assisted interfacial polymerization method. In this method, amine and acyl chloride monomer solutions were electrosprayed into micro-droplets to allow a controlled growth of the polyamide rejection layer. At the same time, CNTs were uniformly dispersed under the action of the electrical field. The loading of CNTs in the polyamide rejection layer markedly enhance the water permeability of the membrane with a 2–6 folds enhancement. The simple and versatile electrospray-assisted interfacial polymerization method, which allows simultaneous control of rejection layer thickness and dispersion of nanomaterials, paves a new dimension for the preparation of high performance ultrathin nanocomposite membranes.

Iridium substitution in nickel cobaltite renders high mass specific OER activity and durability in acidic media

Oxygen evolution reactions being kinetically sluggish and highly expensive remains bottleneck in high pressure hydrogen production from acidic solution water electrolysis. Process economization is mostly affected due to larger consumption of precious iridium as an anodic catalyst. Therefore, effective utilization of noble metal remains a major challenge to be overwhelmed. Comprehensive theoretical and experimental studies show electronic dependency on different structural motifs of IrOx. However, due to lack of suitable non-noble host structures for iridium substitution there is hindrance in implementation. In current study, we explored inverse spinel, nickel cobaltite, as a host structure that provides OER beneficial structural motif to iridium sites on account of relatively higher IrO6 edge sharing than in rutile IrO2. Compact presence of octahedras in host structure reduces IrIr bond length for neighboring IrO6 octahedral units in it that further intrinsically improves the iridium sites due to electronic modulations. Specifically, composite comprising 20 mol% iridium in NiCo2-xO4 rendered acid stable 15 folds enhancement in mass specific OER activity relative to IrO2 resulting in substantial reduction of iridium content. Fabricated composite displayed an onset potential and tafel slope of 1.425 V and 40.4 mV dec−1, respectively in relative to 1.475 V and 68.1 mV dec−1 for pure IrO2. Current approach for effectively utilizing precious metal will lead in future for economizing hydrogen production via water splitting.

Nuanced superconductivity in endohedral gallide Mo8Ga41

We report on synthesis and characterization of gallide cluster based Mo8Ga41 superconductor. Transport and magnetization measurements confirm the superconducting transition temperature to be 9.8 K. The upper critical field (Hc2), lower critical field (Hc1), Ginzburg–Landau coherence length ( ξGL) and penetration depth(λ) are estimated to be 11.8 T, 150 G, 5.28 nm, 148 nm respectively. The electronic band structure, density of states and phonon dispersion curve calculations are obtained by using Density Functional Theory. The core level x-ray Photoelectron Spectroscopy (XPS) reveals the binding energy information of the constituting elements Mo and Ga in Mo8Ga41. The valence band spectra from XPS are in good agreement with calculated density of states (DOS). The zero field critical current density (Jc) at T = 2 K is ∼3 × 105 A/cm2 which is indicative of efficient flux pinning in the as grown compound. About two fold enhancement in critical current density with application of external pressure (1.1 GPa) is observed with marginal decrease in transition temperature. The fitting of current density to double exponential model confirms possibility of two gap superconductivity in Mo8Ga41.

Pivotal role of fluxes in BaTiO3:Eu3+ nano probes for visualization of latent fingerprints on multifaceted substrates and anti-counterfeiting applications

In the present work, various fluxes, namely NaCl, NH4F and NaBr assisted solution combustion route was employed to synthesize novel BaTiO3:Eu3+ (5 mol%) nanophosphors. The influence of the fluxes on structural, morphological and photoluminescence properties of the prepared nanophosphors was investigated in detail. The powdered X-ray diffraction results confirm the cubic structure of the products. The morphological studies reveal that the prepared samples were spherical in shape with agglomeration. The photoluminescence investigation exhibits considerable enhancement in the red emission intensity due to incorporation of fluxes. It was found that, the NH4F (3 wt%) was considered to be appropriate flux that reduce the forming temperature, improve the morphology and two - fold enhancement in the photoluminescence intensity. The photometric properties of the samples were estimated and were well matched with commercial BaTiO3: Eu3+ phosphor. The optimized BaTiO3:Eu3+ (5 mol%), NH4F (3 wt%) nanophosphors were used as a labeling agent for visualization of latent fingerprints on various porous, semi porous and non-porous surfaces employed by powder dusting method. The visualized fingerprints display highly sensitive, better contrast and small background hindrance. The aforementioned results showcase that the optimized sample was created a new avenue for the facile visualization of latent fingerprints in advanced forensic sciences, anti-counterfeiting and WLED's applications.

Triggered parallel discharge in laser-ablation spark-induced breakdown spectroscopy and studies on its analytical performance for aluminum and brass samples

In laser-ablation spark-induced breakdown spectroscopy (LA-SIBS), the discharge channel is an important factor to affect both analytical sensitivity and lateral resolution on the sample surface. In order to study this effect, a gated pulsed high-voltage power supply was selected as the power source of the spark discharge, the dependence of the discharge channel on the time delay between the high voltage pulse and the laser pulse was studied in this work. It was demonstrated that under suitable laser pulse energy and geometrical arrangement of the electrodes, it was possible to change V-shape discharge to parallel discharge by increasing this time delay. In the V-shape discharge, the spark discharge could ablate more samples and increase the diameters and depths of the craters; however, in the parallel discharge, the spark discharge hardly ablated new samples, to make sure that the spatial resolution in LA-SIBS was only determined by the laser ablation. Under parallel discharge, the intensity of the atomic emission of the plasma decreases with the increasing of time delay but increases with the increasing of the discharge voltage. 4–10 folds enhancement factors have been achieved in the detection limits of the analytes in the employed targets under current experimental conditions. It is suggested that spark discharge under external trigger mode should be selected to realize parallel discharge if high spatial resolution elemental analysis of solid samples is required.