Ayanavaram, India
Ayanavaram, India

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PubMed | International Crops Research Institute for the Semi Arid Tropics ICRISAT, ICRISAT, Indian International Crops Research Institute for the Semi Arid Tropics, Zambia Agriculture Research Institute and NRC Group
Type: Journal Article | Journal: Journal of food protection | Year: 2016

A 3-year comprehensive analysis of aflatoxin contamination in peanut butter was conducted in Zambia, sub-Saharan Africa. The study analyzed 954 containers of 24 local and imported peanut butter brands collected from shops in Chipata, Mambwe, Petauke, Katete, and Nyimba districts and also in Lusaka from 2012 to 2014. For analysis, a sample included six containers of a single brand, from the same processing batch number and the same shop. Each container was quantitatively analyzed for aflatoxin B1 (AFB1) in six replicates by using competitive enzyme-linked immunosorbent assay; thus, aflatoxin contamination level of a given sample was derived from an average of 36 test values. Results showed that 73% of the brands tested in 2012 were contaminated with AFB1 levels >20 g/kg and ranged up to 130 g/kg. In 2013, 80% of the brands were contaminated with AFB1 levels >20 g/kg and ranged up to 10,740 g/kg. Compared with brand data from 2012 and 2013, fewer brands in 2014, i.e., 53%, had aflatoxin B1 levels >20 g/kg and ranged up to 1,000 g/kg. Of the eight brands tested repeatedly across the 3-year period, none consistently averaged 20 g/kg. Our survey clearly demonstrates the regular occurrence of high levels of AF B1 in peanut butter in Zambia. Considering that some of the brands tested originated from neighboring countries such as Malawi, Zimbabwe, and South Africa, the current findings provide a sub-Saharan regional perspective regarding the safety of peanut butter.


PubMed | University of Malawi, University for Development Studies, National Institute for Scientific and Industrial Research NISIR, International Crops Research Institute for the Semi Arid Tropics ICRISAT and NRC Group
Type: Journal Article | Journal: Mycotoxin research | Year: 2016

This study assessed knowledge, attitude, and practices (KAP) of the public in Malawi on issues related to molds in foodstuffs. A survey involving structured questionnaire was conducted with 805 respondents from seven districts of Malawi. Descriptive statistics, t tests, and analyses of variance were calculated. A majority of respondents recognized that molds were dangerous to human health (88%); however, about 50% of respondents were not informed that mold toxins are thermally stable and that they are not destroyable by normal cooking processes. About 33% of the respondents asserted that they buy moldy maize, while approximately 20% of respondents reported that they consume moldy fruits having discarded moldy fraction. There were significant differences in knowledge scores among different demographic groups. Females had significantly (p<0.05) lower knowledge scores on issues related to molds in foods. Additionally, the respondents location had a significant effect. However, respondents education had subtle effect on knowledge score and the overall populations knowledge score was generally low (3.551.32 score out of 9). Results of the study underline the need to raise publics knowledge about health risks associated with spoilage molds in food and prevention and management options.


Pokrass M.,NRC Group | Pokrass M.,Tel Aviv University | Azulay D.,Hebrew University of Jerusalem | Balberg I.,Hebrew University of Jerusalem | And 4 more authors.
Journal of Sol-Gel Science and Technology | Year: 2014

Electrical properties of multi-walled carbon nanotubes (MWNTs)/hybrid-glass nanocomposites prepared by the fast-sol-gel reaction were investigated in light of percolation theory. A good correlation was found between the experimental results and the theory. We obtained a percolation threshold c = 0.22 wt%, and a critical exponent of t = 1.73. These values are reported for the first time for a silica-based system. The highest conductivity measured on the MWNT/hybrid-glass nanocomposites was σ ≈ 10-3(Ω cm)-1 for 2 wt% carbon nanotube (CNT) loading. The electrical conductivity was at least 12 orders of magnitude higher than that of pure silica. Electrostatic force microscopy and conductive-mode atomic force microscopy studies demonstrated conductivity at the micro-level, which was attributed to the CNT dispersed in the matrix. It appears that the dispersion in our MWNT/hybrid-glass system yields a particularly low percolation threshold compared with that of a MWNT/silica-glass system. Materials with electrical conductivities described in this work can be exploited for anti-static coating. © 2014 Springer Science+Business Media New York.


Pokrass M.,NRC Group | Burshtein Z.,Ben - Gurion University of the Negev | Gvishi R.,NRC Group
Optical Materials | Year: 2010

We have investigated the effect of organic content in hybrid organic/inorganic glasses prepared by the sol-gel process on the thermo-optic coefficient dn/dT. The organic phase consisted of homogeneously dispersed methyl groups within an inorganic silica matrix. Analysis of Fresnel reflectance temperature dependence of an optically polished sample-surface yielded the desired value, with an accuracy of 10 5/°C. A negative linear dependence of the thermo-optic coefficient on the volumetric thermal expansion coefficient β was obtained, dn/dT[10 4/°C] = -1.1-0.45β[10 4/°C]. Using Prod'homme's model, a negative value was derived for the electronic polarizability coefficient Φ = (-1.8 ± 0.3) × 10 4/°C. The negative sign of Φ is attributed to isolation of the silica matrix sections by the methyl groups, causing the sections to distance upon increase in temperature. © 2010 Elsevier B.V. All rights reserved.


Pokrass M.,NRC Group | Pokrass M.,Tel Aviv University | Burshtein Z.,Ben - Gurion University of the Negev | Gvishi R.,NRC Group | Nathan M.,Tel Aviv University
Optical Materials Express | Year: 2012

The saturated optical absorption of multi-walled carbon nanotube (MWNT)-doped hybrid-glass composites was studied at 1064 nm with nanosecond long pulses using the Z-scan technique. Increased transmission was demonstrated for high intensity pulses. The results were modeled for the limiting cases of a slow or a fast saturable absorber, both referring to a three-level system. The ground-state absorption cross section was estimated as 2.3x10-18 cm2, in good agreement with that of a single carbon atom. The excited state absorption cross section for carbon nanotubes (CNTs) was estimated for the first time as 6.9x10-19 cm3. The absorber's density of 2.8x1018 cm-3 is smaller by approximately a factor of 5 compared to the nominal density of carbon atoms incorporated into the glass. This could be a result of the broad band-like states formation in the MWNTs. The above figures were obtained by assuming that the excited state decay time was longer than the pulse duration of ~1 ns. © 2012 Optical Society of America.


Sheinker A.,NRC Group | Ginzburg B.,NRC Group | Salomonski N.,NRC Group | Frumkis L.,Ben - Gurion University of the Negev | Kaplan B.-Z.,Ben - Gurion University of the Negev
Measurement Science and Technology | Year: 2014

Low frequency magnetic fields feature high penetration ability, whichallowscommunication, localization, and tracking in environments where radio or acoustic waves are blocked or distorted by multipath interferences. In the present work, we propose a method for tracking a magnetic receiver using beacons of low frequency magnetic field, where the receiver includes a tri-axial search-coil magnetometer. Measuring the beacons' magnetic fields and calculating the total-field signals enables localization without restrictions on magnetometer orientation, allowing on-the-move tracking. The total-field signals are used by a global search method, e.g., simulated annealing (SA) algorithm, to localize the receiver. The magnetic field produced by each beacon has a dipole structure and is governed by the beacon's position and magnetic moment. We have investigated two different methods for estimating beacons' magnetic moments prior to localization. The first method requires directional measurements, whereas for the second method the total-field signal is used.Effectiveness of these methods has been proved in numerous field tests. In the present work, we introduce a method for tracking a moving receiver by successive localizations. Using previous localization as a starting point of the search method for the next localization can reduce execution time and chances for divergence. The proposed method has been tested using numerous computer simulations. Successful system operation has been verified in field conditions. The good tracking capability together with simple implementation makes the proposed method attractive for real-time, low power field applications, such as mobile robots navigation. © 2014 IOP Publishing Ltd.


Matsuoka T.,University of Michigan | McGuffey C.,University of Michigan | Cummings P.G.,University of Michigan | Horovitz Y.,University of Michigan | And 10 more authors.
Physical Review Letters | Year: 2010

Stimulated Raman side scattering of an ultrashort high power laser pulse is studied in experiments on laser wakefield acceleration. Experiments and simulations reveal that stimulated Raman side scattering occurs at the beginning of the interaction, that it contributes to the evolution of the pulse prior to wakefield formation, and also that it affects the quality of electron beams generated. The relativistic shift of the plasma frequency is measured. © 2010 The American Physical Society.


Berkovic G.,NRC Group | Zilberman S.,NRC Group | Shafir E.,NRC Group
IEEE SENSORS 2013 - Proceedings | Year: 2013

We show, both theoretically and experimentally, the effect of changes in temperature on measurements of distance and displacement by a typical commercial chromatic confocal sensor. A temperature change of even 1°C can lead to an error which is larger than the specified absolute accuracy of the sensor. The dominant factor in this effect is the change of the refractive index of the optics with temperature. A correction procedure is described which yields high accuracy (better than 5μm) over a temperature range from -5 to 55 oC. © 2013 IEEE.


Berkovic G.,NRC Group | Zilberman S.,NRC Group | Shafir E.,NRC Group
Optics InfoBase Conference Papers | Year: 2012

We report and explain anomalous results obtained when using small core optical fibers to probe the distance to some scattering surfaces, such as machined metal surfaces. Large intensity variations occur when different sections of the surface are probed at constant distance. This is explained using a model which includes ray tracing and reflection from a surface structure exhibiting a variable surface normal vector. When the collection fiber size is increased, a larger portion of the reflected light field is sampled, and the signal intensity variations weaken. © 2012 OSA.


Berkovic G.,NRC Group | Shafir E.,NRC Group
Advances in Optics and Photonics | Year: 2012

This tutorial reviews various noncontact optical sensing techniques that can be used to measure distances to objects, and related parameters such as displacements, surface profiles, velocities and vibrations. The techniques that are discussed and compared include intensity-based sensing, triangulation, time-of-flight sensing, confocal sensing, Doppler sensing, and various kinds of interferometric sensing with both high- and low-coherence sources. © 2012 Optical Society of America.

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