Single/Dual/Triple Broadband Metasurface Based Polarisation Converter with High Angular Stability for Terahertz Applications

This paper presents design and characterisation of a new compact metasurface based linear polarisation converter for terahertz applications. The metasurface unit cell with periodicity of 0.292λ0 consists of an asymmetrically oriented planar double semicircular goblet-shaped resonators. It is printed on a polydimethylsiloxane (PDMS) dielectric substrate backed by a gold layer that acts as a ground plane. This metasurface structure exhibits a broadband cross-polarisation conversion in the frequency range of 0.72−0.99 THz with a polarisation conversion ratio (PCR) > 95% and angular stability > 40∘ for both TE and TM modes. However, the PCR for the single band is >99% at resonant frequencies of 0.755 and 0.94 THz, while the optimised design shows 100% PCR over a BW of 95 GHz. Furthermore, slight modification and optimisation of the broadband design results in quad-ring and slotted DSGRs that produce dual and triple broadband polarisation conversion, respectively. The quad-ring DSGR performs polarisation conversion for frequency range of 0.70−1.08 and 1.61−1.76 THz while the slotted DSGR shows the triple broadband cross-conversion for frequency range of 0.67−0.85, 1.04−1.11, and 1.62−1.76 THz with PCR > 95%. This design is simple, easy to modify to implement single and multi broadband polarisation conversion with high PCR at terahertz regime. In addition to that, it is easy to fabricate and integrate with other components like multiple-input multiple-output terahertz antennas for mutual coupling reduction.

Alkali-cation-incorporated and functionalized iron oxide nanoparticles for methyl blue removal/decomposition

Enhancing the rate of decomposition or removal of organic dye by designing novel nanostructures is a subject of intensive research aimed at improving waste-water treatment in the textile and pharmaceutical industries. Despite radical progress in this challenging area using iron-based nanostructures, enhancing stability and dye adsorption performance is highly desirable. In the present manuscript alkali cations are incorporated into iron oxide nanoparticles (IONPs) to tailor their structural and magnetic properties and to magnify methyl blue (MB) removal/decomposition capability. The process automatically functionalizes the IONPs without any additional steps. The plausible mechanisms proposed for IONPs incubated in alkali chloride and hydroxide solutions are based on structural investigation and correlated with the removal/adsorption capabilities. The MB adsorption kinetics of the incubated IONPs is elucidated by the pseudo second-order reaction model. Not only are the functional groups of -OH and -Cl attached to the surface of the NPs, the present investigation also reveals that the presence of alkali cations significantly influences the MB adsorption kinetics and correlates with the cation content and atomic polarizability.

An Investigation on the Coinfection of Measles and HSV-1 in Hospitalized Acute Encephalitis Syndrome Patients in Eastern India

Acute encephalitis syndrome (AES) is a clinical condition that occurs due to infectious and noninfectious agents- however, viruses are considered to be the dominant pathogen. agents- however, viruses are considered to be the dominant pathogen. In this study, suspected AES cases were enrolled and tested for viral etiology through serology and polymerase chain reaction (PCR)/reverse transcriptase PCR from August 2012-July 2013. During this period, 820 cases were investigated and 96 cases were diagnosed to have a viral etiology whereas 20 patients had IgM antibodies for measles in serum and HSV-1 DNA in cerebrospinal fluid. All 20 of the patients were children below 14 years of age. The median hospital stay was 15 days (IQR: 14.2-17 days) and median GCS score was 7(IQR: 6-8) and were significantly different with patients with co-infections when comapred with patients having HSV-1 infection only. It may be suspected that the measles infection may have a role in the pathogenesis and thus an impact on the prognosis of the AES when present with HSV-1.

Epidemiological and clinical profile of Influenza A(H1N1) pdm09 in Odisha, eastern India

Epidemic of flu is highly contagious and it spreads through air. In 2009 H1N1 influenza virus emerged after reassortment of North American TRIG and Eurasia Avian like virus of swine and started epidemic in Mexico. The first cases were reported from Hyderabad city on 16th May 2009 in India that spread rapidly within a short span of time. During this period large population of Odisha situated at the eastern side of India was also affected and incidences of H1N1 cases were recorded through state Government surveillance system. In this study real time RT-PCR based diagnosis was conducted for the throat swabs collected from suspected H1N1 cases in Odisha during 2009–2017. A total of 2872 throat swabs were received from 23 different Government and private hospitals and 21.1% positivity was confirmed. The disease affected mostly 46–60 years age group, males (50.6%) being more affected. The clinical features had shown that fever with cough (89.6%) was the most common symptom followed by shortness of breath (72.7%). Post monsoon was the peak season in which most of the cases were reported. Neurological signs, pregnancy, diabetes and hypertension were found to be risk factors for H1N1. The case fatality rate (CFR) was 15%.

Molecular and phylogenetic analysis of the dengue strains circulating in Odisha, India

Dengue has emerged as a major public health challenge in terms of both changing clinical pattern and epidemiological features. The state of Odisha reported first dengue epidemic in the year 2010 and this continued each year in epidemic form during post monsoon period gradually becoming an endemic phenomenon. Present study depicts the changing epidemiological and clinical pattern of dengue with reference to its serotypes and genotypes. The study included 5320 suspected dengue cases from different health facilities of the state during 2010-2017. Dengue NS1 antigen and IgM antibody was done through ELISA. Serotyping was done through RTPCR by amplifying a part of core-pre-membrane gene (CprM) followed by sequencing and phylogenetic analysis. Dengue IgM antibody in 17.7% cases and NS1 antigen in 53.20% cases was detected. Dengue serotype 2 (DEN-2) was the only serotype detected in 2010 and 2011 where as all four serotypes 1, 2, 3, 4 were detected in 2012-2017, DEN-2 being dominant but in 2017 DEN-3 was found to be dominant. Phylogenetic analysis revealed genotype IV of DEN-2 and genotype III of DEN-1 and DEN-3 circulating in this region. In 6 cases involvement of DEN-2 in clinically evident encephalitis cases is an important observation in this region and needs public health attention. High prevalence of dengue was observed without any previous reported outbreaks in the state with increased number of cases from 2010 to 2012 affecting both urban and rural areas. High incidence in 2012 was due to co-circulation of more than one serotype which continued in the following years. Severity in some cases was associated with mixed infection but in most cases it was mild indicating the endemic nature of the virus in most parts of Odisha.

Microwave assisted synthesis of magnetite nanoparticles

Magnetite nanoparticles of size ranging from 7-10 nm are prepared from aqueous solutions of Fe2+ and Fe3+ by microwave irradiation at different reaction temperatures ranging from 50 to 200 °C. The effect of reaction temperature on the structural and magnetic properties of nanoparticles is studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Small angle X-ray scattering (SAXS), Thermo gravimetry (TGA), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR) techniques. The average size of the prepared particles, obtained from SAXS, is found to vary from 11 to 15±1 nm as the reaction temperature is increased from 50 to 200 °C. The weight gain curves under an external magnetic field show slope changes at 300 and 596 °C because of the magnetite to maghemite phase transition and ferri to paramagnetic phase transitions, respectively. The ferromagnetic γ-Fe2O3 to antiferromagnetic α-Fe2O3 phase transition temperature is found to be enhanced by 154 °C for the nanoparticles prepared at 200 °C, due to an enhanced activation energy for the cubic to a more compact hexagonal transition. The increase in the phase stability of nanoparticles prepared at elevated temperature is attributed to the diffusion of Na+ in the spinel structure. These results are useful to tailor magnetic particles with enhanced thermal stability for practical applications.

Effect of cation trapping on thermal stability of magnetite nanoparticles

We investigate the effect of sodium trapping on thermal stability of magnetite (Fe3O4) nanoparticles. The pure magnetite nanoparticles incubated in sodium hydroxide solutions and subsequently washed with water to remove the excess sodium. The amount of sodium in magnetite is measured using atomic absorption spectroscopy. The size distribution obtained from Small angle X-ray scattering measurements show that particles are fairly monodisperse. The FTIR spectra of nanoparticles show transmission bands at 441 and 611 cm(-1) are due to the symmetric stretching vibrations (v) of Fe-O in octahedral and tetrahedral sites respectively. With 500 ppm of sodium ions (Na+) in magnetite, the cubic ferrite structure of maghemite (gamma-Fe2O3) to hexagonal hematite (alpha-Fe2O3) phase transition is enhanced by -150 degrees C in air. The Rietveld analysis of sodium doped magnetite nanoparticles show that above 99% of metastable gamma-Fe2O3 is converted to a thermodynamically stable alpha-Fe2O3 after air annealing at 700 degrees C. A decrease in enthalpy observed in doped magnetite unambiguously confirms that the activation energy for maghemite to hematite transition is increased due to the presence of trapped sodium ions. These results suggest that the trapped cations in ferrite nanoparticles can stabilize them by increasing the activation energy.

Influence of renal impairment on plasma concentrations of conjugated bilirubin in cases ofPlasmodium falciparummalaria

In a study of the influence of malaria-associated renal impairment on plasma concentrations of bilirubin, 111 Indian cases of Plasmodium falciparum malaria who had >34.2 microM total bilirubin/litre plasma were investigated. As the aim was to exclude those cases who had concomitant hepatic or (non-malarial) renal dysfunction, 19 cases who had serum concentrations of alanine aminotransferase (ALT) or alkaline phosphatase (AP) that were at least double the normal mean values were withdrawn. Of the remaining 92 patients, 47 showed evidence of renal impairment, the other 45 having plasma concentrations of creatinine that were <177 microM/litre. Plasma concentrations of the liver enzymes ALT and AP were similar for those with and without renal impairment. The plasma concentration of conjugated bilirubin (P<0.02), that of total bilirubin (P<0.05) and the ratio between the two (P<0.01) were, however, all significantly higher in the 47 patients with renal impairment than in the 45 with apparently normal renal function. The plasma concentration of creatinine was found to be not only positively correlated with the plasma concentrations of total (r=0.34; P<0.01) and conjugated (r=0.41; P<0.001) bilirubin but also negatively correlated with the urinary excretion rate for conjugated bilirubin (r=-0.34; P<0.001). The malaria-associated mortality was significantly higher among the patients with renal impairment than among those with apparently normal renal function, with 12 and three deaths, respectively (P<0.001). With increasing renal impairment there therefore appears to be a fall in the renal excretion of conjugated bilirubin. This leads to a disproportionate rise in the plasma concentration of conjugated bilirubin and this, since bilirubin can be toxic to renal tissue, may further worsen the renal impairment.

Association of msp-1, msp-2 and pfcrt genes with the severe complications of Plasmodium falciparum malaria in children

The pathogenesis of severe malaria is still not clearly understood and there are few substantial data describing the association of specific parasite genotypes with the severity of Plasmodium falciparum infection in humans. The merozoite surface proteins 1 and 2 (MSP-1 and MSP-2) of P. falciparum play a crucial role in the parasite's invasion of the human host and the subsequent manifestation of the complications of severe malaria. Attempts at associating msp-1 and msp-2 genotypes with the severity of P. falciparum malaria therefore appear worthwhile. In the present study, based in the malaria-endemic district of Sundergarh, in the Indian state of Orissa, the msp-1, msp-2 and pfcrt genotypes of P. falciparum infecting children were investigated and compared against the severity of malaria in each donor child. The two major complications seen in the subjects, cerebral malaria and severe anaemia, were each found to be significantly associated with the RO33 subtype of msp-1 and the 3D7 subtype of msp-2. Although the study isolates showed a high degree of multiclonicity (multiplicity of infection = 1.9) and of polymorphism in msp-1 and -2, almost all (95%) of the isolates had the K76T mutation in their pfcrt genes.

Adjuvant therapy in cerebral malaria

Cerebral malaria is the most common cause of non-traumatic encephalopathy in the world. The mainstay of therapy is either quinine or artemisinin, both of which are effective antimalarials. The clinical picture of cerebral malaria may persist or even become worse in spite of the clearance of parasites from blood. The death rate is unacceptably high even with effective antimalarials in tertiary care hospitals. The mortality increases in presence of multi organ failure (renal failure, jaundice, respiratory distress, severe anaemia, lactic acidosis, etc.). The pathogenesis of cerebral malaria is multifactorial and includes clogging, sequestration, rosette formation, release of cytokines, cerebral oedema, increased intracranial hypertension, etc. Attempts are made to use adjuvant therapy which will act through alternate mechanisms and address one or more of the pathogenetic processes. In this review, we have discussed the role of corticosteroids, pentoxifylline, desferrioxamine, mannitol and newer agents in the treatment of cerebral malaria. Though the literature on adjuvant therapy in cerebral malaria is large enough, there are a number of shortcomings in the clinical trials, many being open and non randomized or of very small sample size. Further research is of utmost importance through large multicentric, double-blind controlled trials to show the efficacy of any of these drugs.

The influence of hyperbilirubinaemia on malaria-related mortality: an analysis of 1103 patients

The influence of hyperbilirubinaemia on malaria-related mortality was explored among 1103 cases of acute, Plasmodium falciparum malaria at a referral hospital in Orissa, India. Most (64.3%) of the subjects investigated had > 1.2 mg bilirubin/dl serum and were therefore considered hyperbilirubinaemic. Compared with the other patients, those with hyperbilirubinaemia were much more likely to have cerebral malaria (24.1% v. 9.4%; P < 0.0001) or acute renal failure (9.5% v. 2.3%; P < 0.0001), but not severe anaemia (5.9% v. 4.3%; P < 0.22). Mortality was 7.9% among the patients with hyperbilirubinaemia (all the deaths being attributable to cerebral malaria, acute renal failure and/or severe anaemia) but only 1% among the non-hyperbilirubinaemics. There were no deaths, however, among the 506 hyperbilirubinaemics who did not have cerebral malaria, acute renal failure or severe anaemia, even among those with high serum concentrations of bilirubin. It therefore appears that, in acute, Plasmodium falciparum malaria, hyperbilirubinaemia is not in itself a severe complication, and only appears linked with mortality when associated with at least one other complication.

Comparative evaluation of immunochemical methods for estimation of albumin in microalbuminuria

Three immuno assays namely radioimmunoassay (RIA), radial immunodiffusion (RID) and rocket immunoelectrophoresis (RIE) were compared for their performance and utility. The accuracy limits of the methods were compared and also between methods using RIA as the reference. Urine samples, from known diabetic patients with albumin concentration ranging from 2.5 mg/l to 120 mg/l were analysed by the three methods. The mean differences were only 0.91 mg/dl and 0.5 mg/dl respectively for RID vs RIA and rocket vs RIA which is not statistically significant. Excellent correlation was seen between RIA and RIE (r = 0.98) and also between RIA and RID (r = 0.97). Compared to RID, RIE required less time and was more precise. RIA is suited for assaying large sample loads yet not suited for laboratories receiving samples occasionally. For a small pathological laboratory with limited facility rocket electrophoresis may be the most suitable method taking into consideration accuracy, time and cost.