Nanostructured Diatom-ZrO2 composite as a selective and highly sensitive enzyme free electrochemical sensor for detection of methyl parathion

In the current work we report a simple and scalable technique for synthesis of ordered nanoporous Si-ZrO₂ composite derived from the diatom Phaeodactylum tricornutum. The composite was well characterized using SEM, TEM-EDX, FTIR, TGA, BET and DLS. The diatom-ZrO₂ was found to have a specific surface area of 140 m²/g, Si:Zr ratio of 1:4 and a particle size of 80 ± 2 nm. This composite was evaluated as an enzyme free electrochemical sensor towards the detection of methyl parathion (MP) and showed excellent sensing ability at extremely low detection limits of 54.3 pM and a linear concentration range of 3.4 nM to 64 μM. The diatom-ZrO₂ composite was also found to be highly selective towards MP as shown by its response even in the presence of high concentrations of other interfering molecules and ions.

Low Surface Energy and pH Effect on SnO₂ Nanoparticles Formation for Supercapacitor Applications

The SnO₂ nanoparticles formation by hydrothermal method at different experimental conditions such as temperature, pH, reaction time, and capping agent (cetyltrimethylammonium bromide), was studied. X-ray diffraction results confirmed regular rutile crystal structure of SnO₂. The characteristic Raman peak observed at 635 cm^-1 corresponded to A_1g modes of Sn-O vibrations. The study of optical property using photoluminescence confirmed the emissive spectra of SnO₂. The infrared peak observed at 618 cm^-1 corresponded to E_u modes of Sn-O vibrations of TO phonon because of E_⊥ to c-axis. Scanning electron microscope images clearly revealed the formation of complete SnO₂ nanoparticles. The unique SnO₂ nanoparticles stacked together to form microspheres at pH-5 showed high specific capacitance of 274.8 F/g at a current density of 0.5 A/g. The observed results confirmed the feasibility of SnO₂ nanoparticles being used as appropriate positive electrode candidate for supercapacitor applications.

An unusual case of femoral head perforation following fixation with proximal femoral nail antirotation (PFNA-II) for an unstable intertrochanteric fracture: Case report and literature review

The proximal femoral nail antirotation (PFNA-II) is designed for fixation of unstable proximal femoral fractures in Asian patients due to its superior biomechanical properties. The helical blade achieves purchase through bone compaction and requires less removal of bone than a screw. Medial migration of the helical blade with perforation into the hip joint without loss of reduction is a rare problem noted with PFNA. Past literature reporting the migration of the helical blade medially, perforating the femoral head has been addressed as a characteristic complication of the PFNA. A review of literature suggests various reasons for the same such as fresh trauma, fracture settlement and failure of lateralization of the blade. We report a case of postoperative medial migration of the helical blade perforating the femoral head due to loosening of the locking bolt of the helical blade without any signs of rotational or varus displacement of the fracture.

A cholesterol based imidazolium ionic liquid crystal: synthesis, characterisation and its dual application as an electrolyte and electrode material

Dual application of a new cholesterol containing imidazolium ionic liquid crystal as an electrolyte for hybrid flexible supercapacitor and an electrode material in combination with carbon paste.

Structural, Optical and Magnetic Properties of NiO Nanopowders

Nickel oxide (NiO) nanopowders were synthesized without using surfactant by chemical reduction technique. NaBH4 influence on structural, optical and magnetic properties of NiO product was investigated. XRD results revealed the formation of dominant single phase, cubic face centered nickel oxide. Raman peaks depicts the characteristic first-order transverse optical (TO) phonon, two phonon excitation (TO + LO), excitation (2LO) Raman mode vibrations of face centered cubic NiO. PL studies revealed the presence of strong emission band which is in good agreement with the intrinsic NiO product. FTIR studies explored metal oxygen vibrations of the obtained product. TEM results revealed the nanoscale product with spherical shape structures. VSM studies explored weak ferromagnetic behavior of the obtained product. High concentration of NaBH4 increases magnetization value and exhibits the typical weak ferromagnetic curve. Reducing agent played a vital role in the structural, optical and magnetic properties of the obtained NiO product.

Crystal growth and characterization of second- and third-order nonlinear optical chalcone derivative: (2E)-3-(5-bromo-2-thienyl)-1-(4-nitrophenyl)prop-2-en-1-one

Experimental and computational studies of linear and nonlinear optical (NLO) properties of (2E)-3-(5-bromo-2-thienyl)-1-(4-nitrophenyl)prop-2-en-1-one (5B2SNC) single crystals are reported. Good-quality and large-sized single crystals of 5B2SNC were successfully grown and characterized by powder X-ray diffraction and high-resolution X-ray diffractometry techniques. 5B2SNC was found to crystallize in the monoclinic noncentrosymmetric space group Cc and possesses moderately good crystalline perfection. The linear optical properties were investigated using the absorption spectrum, which reveals a direct optical band gap of 3.1 eV. The thermal stability was studied with thermogravimetric analysis/differential thermal analysis. The powder second harmonic generation efficiency was evaluated by the Kurtz and Perry method, and 5B2SNC was found to be 26 times more efficient than urea standard. Third-order NLO properties were studied by the z-scan technique with a femtosecond laser. The second hyperpolarizability was obtained to be ∼1.45 × 10−31 e.s.u. The molecule reveals a strong reverse saturation absorption and negative nonlinear refraction. The molecule exhibited good optical limiting properties, and its limiting threshold was measured to be ∼3.2 mJ cm−2. In addition, static electric dipole moments, linear polarizabilities, and first- and second-order hyperpolarizabilities were calculated by density functional theory (DFT). Highest occupied molecular orbital/lowest unoccupied molecular orbital band gaps were also evaluated by DFT calculations. The experimental and theoretical results showed that 5B2SNC exhibits excellent second- and third-order nonlinear optical properties.

Vertical Alignment of Liquid Crystals Over a Functionalized Flexible Substrate

A simple and effective approach for vertical alignment of liquid crystals (LCs) over a functionalized transparent flexible substrate is described. Surface characterization of this commercially available plastic substrate through X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared spectroscopy (ATR-IR) indicated that cellulose acetate is main component of the transparent substrate. This substrate was chemically functionalized with a suitable LC compound. A trimethoxysilane terminated new rod-shaped mesogen is synthesized and covalently attached to the pre-treated film through silane condensation reaction. LC functionalization of the polymer film is confirmed through contact angle (CA), atomic force microscopy (AFM), XPS and ATR-IR spectroscopy studies. Versatility of the LC modified flexible substrates for the alignment of bulk LC sample at substrate-LC interface was assessed for nematic (N) and smectic A (SmA) phases. Remarkably, LC functionalized cellulose acetate films were found to be highly efficient in assisting a perfect homeotropic alignment of LCs (for both, a room temperature N and a high temperature SmA phase) over the entire area of the LC sample under observation indicating their superior aligning ability in comparison to their unmodified and octadecyltrimethoxysilane (OTS) modified counterparts. The demonstrated method of surface modification of flexible polymer film is easy, surface modified substrates are stable for several months, retained their aligning ability intact and more importantly they are reusable with maximum delivery.

Five-year Retrospective Study on Primary Hyperparathyroidism in South India: Emerging Roles of Minimally Invasive Parathyroidectomy and Preoperative Localization with Methionine Positron Emission Tomography-Computed Tomography Scan

BACKGROUND

Primary hyperparathyroidism (PHPT) is a common endocrine disease with a variable clinical presentation. PHPT is usually symptomatic at presentation in majority of the patients, especially in developing countries. As the accessibility to investigations, advanced imaging methods and surgical procedures are improving, the clinical profile of the patients with PHPT has undergone a palpable change compared to the earlier description. Hence we decided to look for a change in clinical, imaging and surgical outcomes of PHPT patients from South India.

METHODS

We collected the data on clinical presentation, biochemistry, radiological features and operative findings of patients with PHPT treated in our hospital from 2011-2015. Cases of PHPT were identified from the laboratory values using the biochemical criteria, after the exclusion of secondary and tertiary hyperparathyroidism cases.

RESULTS

Our study identified 54 patients (19 males and 35 females) with age ranging from 16 to 71 years. A Significant proportion(38.9%) of the patients were asymptomatic. Musculoskeletal symptoms (40.7%), renal manifestations (27.7%) and gastrointestinal system involvement (27.7%) constituted the other common modes of presentation. CNS involvement was seen in 3 patients. A palpable nodule in the neck was detected in 4 patients. Interestingly 4 patients were managed for parathyroid crisis at presentation. Biochemical features included hypercalcaemia (100%) and hypophosphatemia (59%) with a mean intact PTH level of 602.0±721.3 pg/ml. Sensitivity of Ultrasonography and Tc99M Sestamibi was 72% and 70.6% respectively for detecting a parathyroid adenoma. Sensitivity of C11 methionine PET-CT was 71.4% in those patients who were negative for other imaging modalities. Forty three patients (79.6%) underwent minimally invasive parathyroidectomy.

CONCLUSION

In South India we have a notable change in the clinical presentation of PHPT from a symptomatic to an asymptomatic state. C11 Methionine PET - CT is an emerging modality for preoperative localisation especially when other imaging modalities are negative and when a minimally invasive parathyroidectomy is desired.

Treatment Outcomes in Male Breast Cancer: A Retrospective Analysis of 161 Patients

AIMS

Male breast cancer is a rare disease with limited evidence-based guidelines for treatment. This study aimed to identify demographic, pathological and clinical factors associated with its prognosis.

MATERIALS AND METHODS

A retrospective review of 161 male breast cancer patients diagnosed at a single institution from 1987 to June 2017 was conducted. Patient demographics, disease characteristics, treatment and outcome were extracted and included in competing-risk analysis and the univariate Cox proportional hazard model for univariate analysis. Factors with P < 0.10 were included in multivariable analysis.

RESULTS

The mean age at diagnosis was 67 years (standard deviation = 11.2) and the median follow-up duration was 5.3 years (range 0-25 years). There were 48 deaths, including 23 cancer-specific deaths. The actuarial median survival was 19.9 years. In multivariable analysis, factors associated with overall survival were size of tumours (hazard ratio 2.0; 95% confidence interval 1.4-2.7, P < 0.0001) and diagnosis of metastatic disease (hazard ratio 8.7; 95% confidence interval 1.9-40.6; P = 0.006). Of 138 patients without metastases at diagnoses, 11 had local-regional recurrence and 26 had distant metastases. In the multivariable model for local-regional recurrence, a more recent year of diagnosis was associated with reduced risk (hazard ratio 0.9, 95% confidence interval 0.8-1.0, P = 0.008), whereas more positive lymph nodes was associated with higher risk (hazard ratio 2.2, 95% confidence interval 1.2-4.0, P = 0.01). A higher risk of metastases was associated with more positive lymph nodes (hazard ratio 1.9; 95% confidence interval 1.1-3.3; P = 0.03) and tumour size (hazard ratio 1.8; 95% confidence interval 1.1-2.9; P = 0.01). A higher risk of any recurrence or metastases was associated with the number of positive nodes (hazard ratio 1.9; 95% confidence interval 1.2-3.0; P = 0.005) and tumour size (hazard ratio 1.6; 95% confidence interval 1.1-2.2; P = 0.01).

CONCLUSION

In general, tumour size and more positive lymph nodes were associated with worse prognosis. Larger powered studies are needed to identify prognostic factors with smaller effect sizes.

Effect of phenol red dye on monocrystal growth, crystalline perfection, and optical and dielectric properties of zinc (tris) thiourea sulfate

In this work, the growth of large size (∼25 × 29 × 5 mm and ∼25 × 24 × 6 mm) colorful single crystals of zinc (tris) thiourea sulfate (ZTS) in the presence of 0.05–2 wt% phenol red (PR) dye was achieved using a simple and low-cost technique. Powder X-ray diffraction patterns confirm the presence of PR dye, which is indicated by an enhancement of the Raman peak intensities, a shift in their position and the appearance of a few extra peaks. The quality of the grown crystals was assessed by high-resolution X-ray diffraction, which shows that the crystalline perfection of 1 wt% PR-dyed ZTS crystals is better than that of 2 wt% PR-dyed crystals. The measured UV–vis absorbance spectra show two additional, strong absorption bands at ∼430 and 558 nm in the dyed crystals, due to the presence of PR dye, along with a band at ∼276 nm which is present for all crystals but is slightly shifted for the dyed crystals. Photoluminescence spectra were recorded at two excitation wavelengths (λexc= 310 and 385 nm). The luminescence intensity is found to be enriched in dyed crystals, with some extra emission bands. An enhancement in the value of the dielectric constant and a.c. electrical conductivity was also observed in the dyed ZTS crystals.

Controlled Growth of Gold Nanostars: Effect of Spike Length on SERS Signal Enhancement

Two different types of gold nanostars (Au NS), namely, short-spiked nanostars (SSNS) and long-spiked nanostars (LSNS), are prepared by using a hexagonal lyotropic liquid-crystalline (LLC) phase as a template. The formation, size and length of spikes or arms of the resultant Au NS are controlled by preparation in either a hexagonal LLC phase or an isotropic phase. These NS are anchored onto indium tin oxide (ITO) electrodes through a self-assembled monolayer of 3-mercaptopropyltrimethoxysilane, which acts as a linker molecule. Structural and morphological characterisations of SSNS- and LSNS-anchored ITO electrodes are performed by means of microscopic and spectroscopic analyses. Further electrochemical techniques, namely, cyclic voltammetry and electrochemical impedance spectroscopy, are also used to confirm the immobilisation of these Au NS on ITO electrodes and to study the electrochemical characteristics. These studies clearly reveal the formation of star-shaped, branched, anisotropic nanostructures of gold during the template preparation method and these Au NS are successfully anchored onto ITO electrodes through a covalent immobilisation strategy. Furthermore, the SERS activity of these Au NS is analysed by using glutathione and crystal violet as analytes and by employing glass and ITO as substrates. It is interesting to note that SSNS show a significant enhancement in SERS signals relative to those of LSNS.