Hierarchical self-assembling and helical structure in focal conic domains in meniscus of ferroelectric liquid crystal.

We investigate experimentally the formation of focal conic domains of the ferroelectric phase of a liquid crystal, chiral smectic C (SmC^{*}), in the meniscus geometry. The meniscus geometry is formed in the gap between two glass plates which are placed on a common substrate. This gap is called here a physical cavity.

Technological advancements in bio-recognition using liquid crystals: Techniques, applications, and performance.

The application of liquid crystal (LC) materials has undergone a modern-day renaissance from its classical use in electronics industry as display devices to new-fangled techniques for optically detecting biological and chemical analytes. This review article deals with the emergence of LC materials as invaluable material for their use as label-free sensing elements in the development of optical, electro-optical and electrochemical biosensors. The property of LC molecules to change their orientation on perturbation by any external stimuli or on interaction with bioanalytes or chemical species has been utilized by many researches for the fabrication of high sensitive LC-biosensors.

A Randomized Control Trial of 3 IU IV Oxytocin Bolus with 7 IU Oxytocin Infusion versus 10 IU Oxytocin Infusion During Cesarean Section for Prevention of Postpartum Hemorrhage.

Purpose: Oxytocin is the preferred choice for prophylaxis and treatment of postpartum hemorrhage. Intravenous infusion has been a widely accepted route for Oxytocin administration. However, intravenous bolus route is not a readily preferred route due to apprehensions regarding hypotension that it may cause.

Menstrual Morbidities, Menstrual Hygiene, Cultural Practices during Menstruation, and WASH Practices at Schools in Adolescent Girls of North Karnataka, India: A Cross-Sectional Prospective Study.

Background: Issues of menstrual morbidities, menstrual hygiene, and cultural practices are rarely discussed by adolescents. The burden of menstruation and cultural practices which the adolescent girls have to face has been less quantified. This study aims to assess the issues related to menstruation in school girls.

Correlation between alignment geometries and memory effect in a surface-stabilized ferroelectric liquid crystal.

Memory effect in weakly aligned surface stabilized ferroelectric liquid crystal (SSFLC) material has been investigated by electro-optical and dielectric spectroscopy in three configurations of alignment: antiparallel, 90^{∘} twisted, and unaligned planar samples. It has been observed that two types of molecular dynamics exist in antiparallel rubbed cell in which memory effect is observed for longer duration than in other samples. One dielectric relaxation process is near the surface of the electrode and a second is in the bulk of the SSFLC.

Collective dielectric processes at the transition temperature of the Sm-C^{*} and Sm-A^{*} phase in a ferroelectric liquid crystal.

An anomalous dielectric relaxation process, called the partially unwound helical mode (p-UHM), is a collective dielectric process apart from the well known Goldstone and soft mode process; it is studied in the smectic C^{*} (Sm-C^{*}) phase and at the transition temperature of the Sm-C^{*}-Sm-A^{*} phase in the ferroelectric liquid crystal (FLC) material. To avoid the surface effect, a thick cell of 40 μm thickness was prepared with highly rubbed surfaces of the ITO substrates. It has been observed that the dielectric properties in Sm-C^{*} and at the T_{c} temperature are dominated by the p-UHM process which is dependent on an applied oscillating field in the Sm-C^{*} phase.

Interfacial behavior of confined mesogens at smectic-C*-water boundary.

In this paper, we have investigated the behavior of mesogens at smectic-C*-water interface confined in a liquid crystal (LC) cell with interfacial geometry. Polarized optical microscopy was used to probe the appearance of various smectic-C* domain patterns at water interface owing to the reorientation of mesogens. The undulated stripe domains observed at the air interface of smectic-C* meniscus vanished as the water entered into the smectic layers and focal conical domain patterns appeared at smectic-C*-water boundary.

Dielectric relaxation process of a partially unwound helical structure in ferroelectric liquid crystals.

The fluctuations of unwound helical structure have been observed in deformed helix ferroelectric liquid crystal (DHFLC) and conventional FLC sample cells. The helix is partially unwound by strong anchoring on the substrates. In such sample cells, the helical decarlization lines are not observed in the texture under crossed polarized microscope.

Tyrosinase conjugated reduced graphene oxide based biointerface for bisphenol A sensor.

We have fabricated a nanocomposite of reduced graphene oxide (rGO) sheets and chitosan (Cn) polymer based highly sensitive electrochemical biosensor for detection of bisphenol A (BPA). The two-dimensional structure and chemical functionality of rGO and Cn provide an excellent electrode surface for loading of tyrosinase enzyme molecules. This rGO-Cn nanocomposite is capable of effectively utilizing their superior conductivity, larger effective surface area and superior electrochemical performance due to its synergistic effect between rGO and Cn.

Self assembled DC sputtered nanostructured rutile TiO₂ platform for bisphenol A detection.

A novel biosensor platform comprising of the functionalized sputtered rutile nanostructured titanium dioxide (nTiO2) for rapid detection of estrogenic substance (bisphenol A) has been proposed. The direct current (DC) sputtering of titanium (Ti) on glass substrate has been converted to ordered nanostructured TiO2 film via oxidation. The nanostructured TiO2 surface was functionalized with self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde.

Probing the dynamics of geometrically confined ferroelectric mesogens at the air interface.

This article focuses on the alignment and dynamics of mesogens at the ferroelectric liquid crystal (FLC)/air interface in a confined geometry. The interface has been systematically prepared and characterised with provision for applying an electric field separately to the bulk and air interface of the FLC. Polarizing optical microscopy (POM) investigations done at the FLC/air interface have exposed the concave geometry, cell thickness dependent boundary width and phase dependent optical textures of the FLC meniscus at the interface.

Pearl shaped highly sensitive Mn3O4 nanocomposite interface for biosensor applications.

An electrochemical biosensor based on manganese oxide (Mn3O4) and chitosan (Cn) nanocomposite has been fabricated for fish freshness detection. The electrophoretic deposition of Mn3O4 nanoparticles (15-20 nm) with Cn has changed their morphological arrangement leading to pearl shaped of Mn3O4-Cn nanocomposite on indium tin oxide substrate. Size and morphology of nanocomposite have been confirmed by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Advances in gold nanoparticle-liquid crystal composites.

We present the advancement in the research of the dispersion of gold nanoparticles (GNPs) in thermotropic calamitic liquid crystals. The formation/behavior of surface plasmon resonance (SPR) in GNPs is briefly described. The uniform dispersion of GNPs into liquid crystals along with two important aspects, i.

Ultrasensitive electrochemical immunosensor based on Pt nanoparticle-graphene composite.

We report a protein antibody, Ab-CRP, functionalized Pt nanoparticle-decorated chemical vapor deposition (CVD)-grown graphene on glassy carbon electrode, as a bioelectrode, for the quantitative analysis of human C-reactive protein (CRP). Chemical vapor deposition was used to grow a polycrystalline graphene film on copper and was mounted over a glassy carbon electrode after copper etching through π-π stacking. Ab-CRP was covalently immobilized on mercaptopropionic acid (MPA)-capped Pt nanoparticles that were covalently anchored over the graphene to form a bioelectrode.

Liquid-crystal phase-shifting lateral shearing interferometer with improved fringe contrast for 3D surface profilometry.

We report the development of a common-path and nonmechanical scanning phase-shifting lateral shearing interferometer based on a homogeneous gap and wedge-shaped gap liquid-crystal (LC) cell. The modified cell consists of semi-reflecting and fully reflecting glass plates with LC material sandwiched between them so that the amount of reflected light from both the surfaces is nearly equal, thus generating high contrast interference fringes. The thickness of the LC cell was maintained at ~3 μm uniformly for a homogeneous gap and a varying wedge gap was also introduced between two glass plates.

Microstructural and electrochemical impedance characterization of bio-functionalized ultrafine ZnS nanocrystals-reduced graphene oxide hybrid for immunosensor applications.

We report a mercaptopropionic acid capped ZnS nanocrystals decorated reduced graphene oxide (RGO) hybrid film on a silane modified indium-tin-oxide glass plate, as a bioelectrode for the quantitative detection of human cardiac myoglobin (Ag-cMb). The ZnS nanocrystals were anchored over electrochemically reduced GO sheets through a cross linker, 1-pyrenemethylamine hydrochloride, by carbodiimide reaction and have been characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The transmission electron microscopic characterization of the ZnS-RGO hybrid shows the uniform distribution of ultra-fine nanoparticles of ZnS in nano-sheets of GO throughout the material.

Enzyme-modified indium tin oxide microelectrode array-based electrochemical uric acid biosensor.

We fabricated a miniaturized electrochemical uric acid biosensor with a 3-aminopropyltriethoxysilane (APTES)-modified indium tin oxide (ITO) microelectrode array (μEA). The ITO-μEA on a glass plate was immobilized with the enzyme uricase, through a cross-linker, bis[sulfosuccinimidyl]suberate (BS). The enzyme-immobilized electrode (uricase/BS/APTES/ITO-μEA/glass) was characterized by atomic force microscopy and electrochemical techniques.

Electrochemical impedance spectroscopy characterization of mercaptopropionic acid capped ZnS nanocrystal based bioelectrode for the detection of the cardiac biomarker--myoglobin.

3-Mercaptopropionic acid (MPA) capped ZnS nanocrystals (ZnS(MPA)) are covalently attached to a self assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) on an indium-tin-oxide (ITO) coated glass plate. The protein antibody, anti-myoglobin (Ab-Mb), is covalently linked to free carboxyl groups present on ZnS(MPA) nanocrystals via carbodiimide coupling reaction to form a bioelectrode (Ab-Mb(BSA)/ZnS(MPA)/APTES/ITO-glass). This bioelectrode has been characterized using atomic force microscopy (AFM), contact angle measurements, cyclic voltammetry and electrochemical impedance spectroscopy (EIS).

Immobilization of uricase enzyme on self-assembled gold nanoparticles for application in uric acid biosensor.

An enzyme immobilization matrix is described by preparing a self-assembly of gold nanoparticles (GNPs) over a self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) on an indium-tin-oxide (ITO) coated glass plate. The surface of the GNPs was modified with a mixed (1:9) SAM of 11-mercaptoundecanoic acid (MUA) and 3-mercapto-propionic acid (MPA). The enzyme, uricase was covalently immobilized to the carboxyl groups of the mixed SAM of MUA/MPA through carbodiimide coupling reaction.

Effect of cadmium telluride quantum dots on the dielectric and electro-optical properties of ferroelectric liquid crystals.

We present here the dielectric and electro-optical studies of cadmium telluride quantum dots (CdTe QDs) doped ferroelectric liquid crystals (FLCs). It has been observed that the doping of CdTe QDs not only induced a pronounced memory effect but also affected the physical parameters of FLC material (LAHS19). The modifications in the physical parameters and memory effect of LAHS19 are found to depend on the concentration ratio of CdTe QDs.

Anisotropic behavior of water in ferroelectric liquid crystals.

The outcome of water addition in ferroelectric liquid crystal (FLC) has been investigated in uniform and defect-free homogeneous and homeotropically aligned monodomain sample cells from electro-optical and dielectric spectroscopic measurements. The lagging in optical response between nonconducting (spatially variable switching) and conducting (conventional switching) portions of water added FLC sample cell has been observed by frequency-dependent electro-optical studies. The bias-dependent water related new relaxation peak near the conventional Goldstone mode relaxation process has been observed only in the homogeneous alignment and not in the homeotropic one.

Effect of carbon nanotubes on response time of ferroelectric liquid crystals.

We present the results of the fast electro-optic response of multiwalled carbon nanotubes (MWCNTs)-doped deformed helix ferroelectric liquid crystal (DHFLC). The fastening of the response in MWCNTs-doped DHFLC has been attributed to the decrease in rotational viscosity and increase in anchoring energy. The decrease in the former is due to the experience of the torque both by MWCNTs and DHFLC and perturbation of order parameter of the DHFLC while the increase in the latter is due to the pi-pi electrons stacking between the MWCNTs, DHFLC molecules, and alignment layers.

Memory effect in weakly anchored surfaces of deformed helix ferroelectric liquid crystals.

A wide-range memory effect in deformed helix ferroelectric liquid crystals (DHFLCs) has been investigated by electro-optical and textural methods. A comparative study has been performed on strongly and weakly anchored surfaces of DHFLC cells. The saturation voltage has been compared in both types of cells by studying the variation of tilt angle and spontaneous polarization with applied voltage.

Optical memory effect in a deformed helix ferroelectric liquid crystal.

Optical memory in a deformed-helix ferroelectric liquid crystal is proposed by deforming the helix under the application of a square-voltage pulse of known magnitude and frequency. This effect is based on the electromechanical effect of helix deformation due to the electric field. When the interaction between the electric field and the dipole is sufficiently strong, all of the dipoles align along the electric field.