Selective, Ultra-sensitive and Rapid Detection of Serotonin by Optimized ZnO Nanorod FET Biosensor

BACKGROUND

Fluctuation in serotonin (5-HT) level is an essential manifestation of several neurological disorders. In view of such importance, it is necessary to monitor the levels of 5-HT with good sensitivity, selectivity, affordability and low response time. Zinc oxide (ZnO) based field effect transistors (FET) with attributes like minimized noise levels and large on-off ratio are regarded as emerging high performance biosensor platforms. However, their response is significantly non-linear and there has been no appreciable endeavor for improving the non-linearity.

METHOD

In this paper, we have introduced embedded gate electrode encompassing the channel of the FET which improves the uniformity in electric field line distribution through the electrolyte and proportionately enhances the capture of target biomolecule at ultra low concentrations, thereby increasing the linearity. Further, we have incorporated the optimized parameters of ZnO nanorods reported previously, for rapid and selective detection of 5-HT.

RESULTS

It has been observed that the fabricated ZnO FET biosensor lowers the detection limit down to 0.1fM which is at least one order of magnitude lower than the existing reports. The sensor also has wide linear range from 0.1fM to 1nM with a detection time of about 20 minutes.

CONCLUSION

The proposed zinc oxide nanorod-based sensor can be used as an excellent tool for future diagnosis of neurological disorders.

Experiment and FEM Analysis of Silica Nanoparticle-Based Impedance Immunosensor for Sensitivity Enhancement

This article investigates the impact of incorporating silica nanoparticles of varying diameters in label free impedance immunosensor. It has been observed that even if the surface area improvement has been adjusted to be similar for all the diameters, the sensitivity is enhanced by five times at a particular diameter of 100 nm due to the optimum combination of intersection with electric field lines and surface convexity. This study has enabled the detection of 0.1 fM Hep-B surface antigen with a reliable sensitivity of around 75%. Further, it has been observed that the SNR corresponding to 0.1 fM is 20 dB only for 100 nm particle. This SNR is comparable to a recent report on Hep-B virus detection but the limit of detection in the proposed sensor is lowered by more than three orders of magnitude.

A musculoskeletal ultrasound program as an intervention to improve disease modifying anti-rheumatic drugs adherence in rheumatoid arthritis: a randomized controlled trial

Objectives: To evaluate the effect of a musculoskeletal ultrasound programme (MUSP) applying real-time ultrasonography with reinforcement of findings by a rheumatologist on improving disease-modifying anti-rheumatic drugs (DMARDs) adherence in rheumatoid arthritis (RA).Method: Eligible RA patients with low adherence score (< 6) on the 8-item Morisky Medication Adherence Scale (MMAS-8) were randomized to either an intervention group (receiving MUSP at baseline) or a control group (no MUSP), and followed up for 6 months. Adherence measures (patient-reported and pharmacy dispensing records) and clinical efficacy data were collected. The MUSP's feasibility and acceptability were assessed.Results: Among 132 recruited RA patients, six without baseline visits were excluded; therefore, 126 patients were analysed (62 intervention and 64 control). The primary outcome (proportion of patients with 1 month MMAS-8 score < 6) was significantly smaller (p = 0.019) in the intervention (35.48%) than the control group (56.25%). However, 3 and 6 month adherence and clinical efficacy outcomes were not significantly different between the two groups (all p > 0.05). All 62 patients completed the MUSP (mean time taken, 9.2 min), with the majority reporting moderately/very much improved understanding of their joint condition (71%) and the importance of regularly taking their RA medication(s) (79%). Most patients (90.3%) would recommend the MUSP to another RA patient.Conclusions: The MUSP improved RA patients' DMARDs adherence in the short term and was feasible and well accepted by patients. Future studies could evaluate whether repeated feedback using MUSP could help to sustain the improvement in DMARD adherence in RA patients, and whether this may be clinically impactful and cost-effective.

Label free, electric field mediated ultrasensitive electrochemical point-of-care device for CEA detection

Developing point-of-care (PoC) diagnostic platforms for carcinoembryonic antigen detection is essential. However, thefew implementations of transferring the signal amplification strategies in electrochemical sensing on paper-based platforms are not satisfactory in terms of detection limit (LOD). In the quest for pushing down LOD, majority of the research has been targeted towards development of improved nanostructured substrates for entrapping more analyte molecules and augmenting the electron transfer rate to the working electrode. But, such approaches have reached saturation. This paper focuses on enhancing the mass transport of the analyte towards the sensor surface through the application of an electric field, in graphene-ZnO nanorods heterostructure. These hybrid nanostructures have been deposited on flexible polyethylene terephthalate substrates with screen printed electrodes for PoC application. The ZnO nanorods have been functionalized with aptamers and the working sensor has been integrated with smartphone interfaced indigenously developed low cost potentiostat. The performance of the system, requiring only 50 µl analyte has been evaluated using electrochemical impedance spectroscopy and validated against commercially available ELISA kit. Limit of detection of 1 fg/ml in human serum with 6.5% coefficient of variation has been demonstrated, which is more than three orders of magnitude lower than the existing attempts on PoC device.

Differentiation of hypertensive heart disease and hypertrophic cardiomyopathy with myocardial stiffness measurements: a shear wave imaging study using ultra-high frame rate echocardiography

Background

Recently, cardiac shear wave (SW) elastography, based on high frame rate (HFR) echocardiography, has been proposed as new non-invasive technique for assessing myocardial stiffness. As myocardial stiffness increases with increasing wall stress, differences in measured operating myocardial stiffness do not necessarily reflect differences in intrinsic myocardial properties, but can also be caused by mere changes in loading or chamber geometry. This complicates myocardial stiffness interpretation for different types of pathologic hypertrophy.

Purpose

To explore the relationship between myocardial stiffness and underlying pathological substrates for cardiac hypertrophy.

Methods

We included 20 patients with hypertension (HT) and myocardial remodelling (59±14 years, 75% male), 20 patients with hypertrophic cardiomyopathy (HCM) (59±16 years, 60% male) and 20 healthy controls (56±14 years, 75% male). Left ventricular (LV) parasternal long axis views were acquired with an experimental HFR scanner at 1293±362 frames per seconds. Propagation velocity of SW occurring after mitral valve closure in the interventricular septum (IVS) served as measure of operating myocardial stiffness (Figure A). To compare myocardial stiffness among hearts with differing loading conditions and chamber geometry, SW velocities were normalized to end-diastolic wall stress, estimated at IVS from regional wall thickness, longitudinal and circumferential regional radii of curvature, and non-invasively estimated LV end-diastolic pressure (EDP).

Results

SW velocities differed significantly between groups (p&lt;0.001). The controls had the lowest SW velocities (4.02±0.97 m/s), whereas values between HT and HCM group were comparable (6.46±0.99 m/s vs. 7.00±2.10 m/s; p=0.738). Considering end-diastolic wall stress, HCM patients had the same SW velocity at lower wall stress compared to HT (Figure B), indicating higher myocardial stiffness in the HCM group. SW velocities normalized for wall stress indicated significantly different myocardial stiffness among all groups (p&lt;0.001) (Figure C). In a multiple linear regression model, the underlying pathological substrate independently influenced SW velocity (beta 1.37, 95% CI (0.78–1.96); p&lt;0.001), while wall stress did not significantly affect its value (p=0.479).

Conclusions

Our study demonstrated that SW elastography can detect differences in myocardial stiffness in hypertensive heart and hypertrophic cardiomyopathy. Additionally, our results suggest that SW velocity is dominated by underlying myocardial tissue properties. We hypothesize that differential changes in cardiomyocytes and/or the extracellular matrix contribute to the differential myocardial stiffening in different pathologic entities of LV hypertrophy. Thus, SW elastography could provide useful novel diagnostic information in the evaluation of LV hypertrophy.

Figure A, B, C

Funding Acknowledgement

Type of funding source: None

National Clinical Guidance for the Management of Cardiovascular Intervention in the COVID-19 Pandemic: From Bangladesh Society of Cardiovascular Interventions (BSCI)

Since the first recorded case of SARS-CoV-2 in Bangladesh on 8th March 2020, COVID-19 has spread widely through different regions of the country, resulting in a necessity to re-evaluate the delivery of cardiovascular services, particularly procedures pertaining to interventional cardiology in resource-limited settings. Given its robust capacity for human-to-human transmission and potential of being a nosocomial source of infection, the disease has specific implications on healthcare systems and health care professionals faced with performing essential cardiac procedures in patients with a suspected or confirmed diagnosis of COVID-19. The limited resources in terms of cardiac catheterization laboratories that can be designated to treat only COVID positive patients are further compounded by the additional challenges of unavailability of widespread rapid testing on-site at tertiary cardiac hospitals in Bangladesh. This document prepared for our nation by the Bangladesh Society of Cardiovascular Interventions (BSCI) is intended to serve as a clinical practice guideline for cardiovascular health care professionals, with a focus on modifying standard practice of care during the COVID-19 pandemic, in order to ensure continuation of adequate and timely treatment of cardiovascular emergencies avoiding hospital-based transmission of SARS-COV-2 among healthcare professionals and the patients. This is an evolving document based on currently available global data and is tailored to healthcare systems in Bangladesh with particular focus on, but not limited to, invasive cardiology facilities (cardiac catheterization, electrophysiology & pacing labs). This guideline is limited to the provision of cardiovascular care, and it is expected that specific targeted pharmaco-therapeutics against SARS-CoV-2 be prescribed as stipulated by the National Guidelines on Clinical Management of Corona virus Disease 2019 (COVID-19) published by the Director General of Health Services, Ministry of Health and Family Welfare of Bangladesh.

156 Shear wave propagation velocity after aortic valve closure could be a novel parameter for myocardial contractility

Funding Acknowledgements

Research Foundation (FWO) Flanders grant

Background

Shear wave imaging is a novel ultrasound technique based on the detection of transverse waves travelling through the myocardium by using high frame rate (HFR) echocardiography. These waves can be induced by an external or internal stimulus, such as aortic valve closure (AVC). The propagation velocity of shear waves is directly dependent on myocardial stiffness. It has been previously suggested in animals that the shear wave propagation velocity at AVC might be related to myocardial contractility.

Aim

The aim of this study was to validate if the shear wave propagation velocity after AVC (end-systole) is related to myocardial contractility.

Methods

Firstly, 11 healthy volunteers (age: 25 ± 4 years; male: n = 11) performed a supine bicycle exercise test. Images were taken at rest and during 25%, 50% and 66% of maximal workload, as determined by previous upright bicycle exercise testing. Secondly, 9 patients (age: 63 ± 10 years; male: n = 7) underwent a dobutamine stress echocardiography. The stress echo was negative in all patients. Images were taken at rest and after a dobutamine administration of 10µg/kg/min and 40µg/kg/min. Left ventricular (LV) parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) (average frame rate: 1217 ± 233fps). Apical 4-chamber views were acquired with a conventional ultrasound machine. Non-invasive single beat end-systolic elastance (Ees) was used as a measure of contractility. Acceleration maps were created from HFR-datasets by drawing a M-mode line along the midline of the interventricular septum. Shear wave propagation speed at AVC (end-systole) was calculated by measuring the slope of the wave front on the acceleration maps (Figure A).

Results

During the bicycle exercise, heart rate (61 ± 11bpm vs. 146 ± 13bpm; p &lt; 0.001), systolic blood pressure (125 ± 12mmHg vs. 173 ± 15mmHg; p &lt; 0.001), LV ejection fraction (55 ± 3% vs. 70 ± 5%; p &lt; 0.001), Ees (1.8 ± 0.3mmHg/ml vs. 3.6 ± 1.0mmHg/ml; p &lt; 0.001) and propagation velocity of the shear waves (3.3 ± 0.5m/s vs. 6.2 ± 1.7m/s; p &lt; 0.01) (Figure B) increased significantly from rest to exercise. Likewise, dobutamine administration significantly increased the heart rate (68 ± 10bpm vs. 131 ± 14bpm; p &lt; 0.001), LV ejection fraction (57 ± 5% vs. 74 ± 7%; p &lt; 0.001), as well as the shear wave velocity after AVC (4.4 ± 0.6m/s vs. 7.2 ± 1.7m/s; p &lt; 0.01) (Figure C) and Ees (2.1 ± 0.4mmHg/ml vs. 3.3 ± 0.8mmHg/ml; p &lt; 0.001). Independent from the stressor, shear wave propagation velocity had a good and significant correlation with Ees (Figure D).

Conclusion

Shear wave propagation velocity after AVC increases with increasing level of exercise or dobutamine dose. Shear wave velocities at AVC show a good correlation with Ees. Our data indicate that end-systolic shear wave velocity is related to myocardial contractility and might therefore be a potential novel parameter for the non-invasive assessment of myocardial function.

Abstract 156 Figure.

417 Can myocardial stiffness measurements distinguish the underlying pathology in hearts with thick walls? A shear wave imaging study using ultra-high frame rate echocardiography

Background

Different pathophysiologic pathways in the development of left ventricular (LV) hypertrophy may alter passive myocardial stiffness differently. Recently, cardiac shear wave (SW) elastography has been proposed as new non-invasive technique for assessing myocardial stiffness.

Purpose

To explore the relationship between myocardial stiffness and the underlying pathological substrates for cardiac hypertrophy.

Methods

We included 17 patients with cardiac amyloidosis (AML) (69 ± 10 years, 41% male), 17 patients with hypertrophic cardiomyopathy (HCM) (59 ± 16 years, 65% male) matched for interventricular septum (IVS) thickness and 17 hypertensive patients (HT) with prominent myocardial remodelling (56 ± 15 years, 71% male). LV parasternal long axis views were acquired with an experimental ultrasound scanner at 1255 ± 354 frames per seconds. Myocardial acceleration maps were created from the HFR-datasets and an anatomical M-mode line was drawn along the midline of the IVS (Figure A). The propagation velocity of natural SWs occurring at mitral valve closure (MVC) was measured on these M-modes in order to assess operating myocardial stiffness. To compare myocardial stiffness among hearts with differing loading conditions and chamber geometry, SW velocities were normalized to operating end-diastolic wall stress. The end-diastolic wall stress was estimated at the IVS from regional wall thickness, longitudinal and circumferential regional radii of curvature, and noninvasively estimated left ventricular end-diastolic pressure (EDP).

Results

IVS thickness was significant different among groups (AML: 1.63 ± 0.33 cm, HCM: 1.69 ± 0.21 cm, HT: 1.48 ± 0.14 cm; p = 0.037). HT patients had significant higher septal radius of curvature compared to other two groups (p &lt; 0.05), while the AML patients had the highest estimated EDP (p &lt; 0.05). All groups had comparable, elevated SW velocities at MVC (AML: 6.49 ± 1.00 m/s, HCM: 6.46 ± 1.45 m/s, HT: 6.22 ± 0.96 m/s; p = 0.752). Considering end-diastolic wall stress, HT patients had the same SW velocity at higher wall stress compared to AML and HCM (Figure B), indicating lower myocardial stiffness in the HT group. SW velocities normalized for wall stress indicated significantly different myocardial stiffness among groups (p = 0.003) (Figure C). The HT group had the lowest normalized myocardial stiffness, whereas values of the AML group overlapped with the HCM group (p = 1.00).

Conclusions

Our study demonstrated that shear wave elastography can detect differences in myocardial stiffness in hearts with thick walls. Considering the effect of wall stress, our results suggest that factors other than chamber geometry and loading condition mediate myocardial stiffness in hearts with thick walls. We hypothesize that differential changes in cardiomyocytes and/or the extracellular matrix contribute to the differential myocardial stiffening in different pathologic entities of LV hypertrophy.

Abstract 417 Figure.

Nonergodicity in silo unclogging: Broken and unbroken arches

We report an experiment on the unclogging dynamics in a two-dimensional silo submitted to a sustained gentle vibration. We find that arches present a jerking motion where rearrangements in the positions of their beads are interspersed with quiescent periods. This behavior occurs for both arches that break down and those that withstand the external perturbation: Arches evolve until they either collapse or get trapped in a stable configuration. This evolution is described in terms of a scalar variable characterizing the arch shape that can be modeled as a continuous-time random walk. By studying the diffusivity of this variable, we show that the unclogging is a weakly nonergodic process. Remarkably, arches that do not collapse explore different configurations before settling in one of them and break ergodicity much in the same way than arches that break down.

P1501Can we measure the stiffening of hypertensive hearts non-invasively? A shear wave imaging study using ultra-high frame rate echocardiography

Background

Cardiac shear wave (SW) elastography is a novel technique based on high-frame-rate (HFR) echocardiography which has been shown to be related to myocardial stiffness. In this study we explore the relation between myocardial SW velocity and myocardial remodelling in remodelled hearts of patients with arterial hypertension (AH).

Methods

We prospectively included 33 treated AH patients with hypertrophic left ventricular (LV) remodelling (59±14 years, 55% male) and 26 aged matched healthy controls (55±15 years, 77% male). AH patients were further divided according to their LV geometric pattern into a concentric remodelling (CR) group (13 patients) and a concentric hypertrophy (CH) group (20 patients). LV parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) at 1266±317 frames per seconds. Myocardial acceleration maps were created from the HFR-datasets and an anatomical M-mode line was drawn along the midline of the interventricular septum (IVS). The propagation velocity of natural SWs occurring at mitral valve closure (MVC) was measured on these M-modes (Figure A) in order to assess passive myocardial stiffness. Standard echocardiography using a commercial scanner was performed to evaluate LV remodelling.

Results

SW velocities at MVC differed significantly between AH patients and controls (5.83±1.20 m/s vs. 4.04±0.96 m/s; p<0.001). Within the patient group, patients with CH had highest SW velocities at MVC (p<0.001), whereas values between controls and patients with CR were comparable (p=0.075) (Figure B). In AH patients, significant positive correlations were found between SW velocity at MVC and parameters of LV remodelling (IVS thickness: r=0.728, p<0.001; LV mass index: r=0.780, p<0.001, LV end-diastolic volume: r=0.604, p=0.008) (Figure C) and also parameters of diastolic function (E/e': r=0.495, p=0.005, left atrium diameter: r=0.866, p<0.001, left atrium volume index: r=0.661, p<0.001).

Figure A, B, C

Conclusions

SW velocity – and therefore myocardial stiffness – is higher in AH patients compared to healthy controls and increases with increasing severity of hypertensive heart disease. Patients with concentric remodelling have still close-to-normal passive myocardial properties while patients with concentric hypertrophy show significant stiffening. Echocardiographic shear wave elastography is a promising new technique for the non-invasive assessment of myocardial stiffness and might provide valuable new insights into myocardial function and the pathophysiology of myocardial disease.

Biology of Oral Streptococci

Bacteria belonging to the genus Streptococcus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of the oral microbiota. In this article, we discuss the different oral environments inhabited by streptococci and the species that occupy each niche. Special attention is given to the taxonomy of Streptococcus, because this genus is now divided into eight distinct groups, and oral species are found in six of them. Oral streptococci produce an arsenal of adhesive molecules that allow them to efficiently colonize different tissues in the mouth. Also, they have a remarkable ability to metabolize carbohydrates via fermentation, thereby generating acids as byproducts. Excessive acidification of the oral environment by aciduric species such as Streptococcus mutans is directly associated with the development of dental caries. However, less acid-tolerant species such as Streptococcus salivarius and Streptococcus gordonii produce large amounts of alkali, displaying an important role in the acid-base physiology of the oral cavity. Another important characteristic of certain oral streptococci is their ability to generate hydrogen peroxide that can inhibit the growth of S. mutans. Thus, oral streptococci can also be beneficial to the host by producing molecules that are inhibitory to pathogenic species. Lastly, commensal and pathogenic streptococci residing in the oral cavity can eventually gain access to the bloodstream and cause systemic infections such as infective endocarditis.

Liquid gated ZnO nanorod FET sensor for ultrasensitive detection of Hepatitis B surface antigen with vertical electrode configuration

Detection of the Hepatitis-B surface antigen at the attomolar level is demonstrated using antibody functionalized liquid gated ZnO nanorods field effect transistor (FET) biosensor with vertical electrode configuration. The sensor is operated in heterodyne mode at high frequency to overcome the problem of Debye screening effect in physiological analyte. Enhanced penetration of the electric field lines through the nanorods enables significant improvement in the limit of detection and sensitivity compared to that of the conventional lateral electrode configuration. The combined effect of the probable change in the threshold voltage and the carrier mobility for vertical electrode configuration lead to a sensitivity of around 75% at 1 fM (which is an enhancement by 200%) and a detection limit of 20 aM with a dynamic range from 20 aM to 1 pM. The detection limit which is achieved with the proposed label free sensor in physiological analyte using antibodies is lowered by more than three orders of magnitude compared to the existing reports.

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction to a_{μ}^{HVP} for the first time with physical values of m_{u} and m_{d} and dynamical u, d, s, and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δa_{μ}^{HVP,m_{u}≠m_{d}}=+1.5(7)%, in agreement with estimates from phenomenology.

Desorption of water from hydrophilic MCM-41 mesopores: positron annihilation, FTIR and MD simulation studies

The desorption mechanism of water from the hydrophilic mesopores of MCM-41 was studied using positron annihilation lifetime spectroscopy (PALS) and attenuated total reflection Fourier transform infrared spectroscopy supplemented with molecular dynamics (MD) simulation. PALS results indicated that water molecules do not undergo sequential evaporation in a simple layer-by-layer manner during desorption from MCM-41 mesopores. The results suggested that the water column inside the uniform cylindrical mesopore become stretched during desorption and induces cavitation (as seen in the case of ink-bottle type pores) inside it, keeping a dense water layer at the hydrophilic pore wall, as well as a water plug at both the open ends of the cylindrical pore, until the water was reduced to a certain volume fraction where the pore catastrophically empties. Before being emptied, the water molecules formed clusters inside the mesopores. The formation of molecular clusters below a certain level of hydration was corroborated by the MD simulation study. The results are discussed.

Assessment of phenol infiltration resilience in soil media by HYDRUS-1D transport model for a waste discharge site

The movement of contaminants through soil imparts a variety of geo-environmental problem inclusive of lithospheric pollution. Near-surface aquifers are often vulnerable to contamination from surface source if overlying soil possesses poor resilience or contaminant attenuation capacity. The prediction of contaminant transport through soil is urged to protect groundwater from sources of pollutants. Using field simulation through column experiments and mathematical modeling like HYDRUS-1D, assessment of soil resilience and movement of contaminants through the subsurface to reach aquifers can be predicted. An outfall site of effluents of a coke oven plant comprising of alarming concentration of phenol (4-12.2 mg/L) have been considered for studying groundwater condition and quality, in situ soil characterization, and effluent characterization. Hydrogeological feature suggests the presence of near-surface aquifers at the effluent discharge site. Analysis of groundwater of nearby locality reveals the phenol concentration (0.11-0.75 mg/L) exceeded the prescribed limit of WHO specification (0.002 mg/L). The in situ soil, used in column experiment, possess higher saturated hydraulic conductivity (KS  = 5.25 × 10(-4) cm/s). The soil containing 47 % silt, 11 % clay, and 1.54% organic carbon content was found to be a poor absorber of phenol (24 mg/kg). The linear phenol adsorption isotherm model showed the best fit (R(2) = 0.977, RMSE = 1.057) to the test results. Column experiments revealed that the phenol removal percent and the length of the mass transfer zone increased with increasing bed heights. The overall phenol adsorption efficiency was found to be 42-49%. Breakthrough curves (BTCs) predicted by HYDRUS-1D model appears to be close fitting with the BTCs derived from the column experiments. The phenol BTC predicted by the HYDRUS-1D model for 1.2 m depth subsurface soil, i.e., up to the depth of groundwater in the study area, showed that the exhaustion point was reached within 12 days of elapsed time. This clearly demonstrated poor attenuation capacity of the soil to retard migration of phenol to the groundwater from the surface outfall site. Suitable liner, based on these data, may be designed to inhibit subsurface transport of phenol and thereby to protect precious groundwater from contamination.

Isolation, culture optimization and physico-chemical characterization of laccase enzyme from Pleurotus fossulatus

Pleurotus fossulatus (Cooke) Sace is member of oyster mushroom can produced extracellular laccase (benzenediol: oxygen oxidoreductase; EC 1.10.3.2) in submerged fermentation. To analyze the optimum production for laccase P. fossulatus was cultured both in stationary and shaking condition in different media. Partial purification of laccase was done after 0-80% ammonium sulphate precipitation, followed by DEAE (Diethylaminoethyl) Sephadex (A-50) anion exchange chromatography. Potato-sucrose peptone (PSP) medium and Potato-dextrose (PD) medium showed highest laccase production in shaking and stationary conditions, respectively. Though the time required for optimum laccase production in stationary condition was much more than the shaking condition but the amount of laccase was about 2.75t greater in former condition. The laccase produced in stationary condition was more stable than the enzyme produced in shaking condition. The partially purified enzyme showed highest affinity towards o-dianisidine than guaiacol and ABTS (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) as evidenced by their K(m). The physico-chemical properties of the laccase suggested the significance of this enzyme in industrial applications.

A novel normalization technique for unsupervised learning in ANN

Unsupervised learning is used to categorize multidimensional data into a number of meaningful classes on the basis of the similarity or correlation between individual samples. In neural-network implementation of various unsupervised algorithms such as principal component analysis (PCA), competitive learning or self-organizing map (SOM), sample vectors are normalized to equal lengths so that similarity could be easily and efficiently obtained by their dot products. In general, sample vectors span the whole multidimensional feature space and existing normalization methods distort the intrinsic patterns present in the sample set. In this work, a novel method of normalization by mapping the samples to a new space of one more dimension has been proposed. The original distribution of the samples in the feature space is shown to be almost preserved in the transformed space. Simple rules are given to map from original space to the normalized space and vice versa.

Enteric fever in an HIV/AIDS patient: Atypical manifestations

Bloodstream infections with Salmonella typhi, is uncommon in human immunodeficiency virus (HIV)-infected persons. The symptoms in such patients are often non-specific and have a rather insidious onset and progression. We report a patient with sepsis and lower limb gangrene due to Salmonella typhi infection in an HIV-infected patient.

Excitable patterns in active nematics

We analyze a model of mutually propelled filaments suspended in a two-dimensional solvent. The system undergoes a mean-field isotropic-nematic transition for large enough filament concentrations, and the nematic order parameter is allowed to vary in space and time. We show that the interplay between nonuniform nematic order, activity, and flow results in spatially modulated relaxation oscillations, similar to those seen in excitable media. In this regime the dynamics consists of nearly stationary periods separated by "bursts" of activity in which the system is elastically distorted and solvent is pumped throughout. At even higher activity, the dynamics becomes chaotic.