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This paper investigates the validity of distributed-cycling schemes on scaled Flash memory technologies. These schemes rely on the possibility to emulate on-field device operation by increasing the cycling temperature according to an Arrhenius law, but the assessment of the activation energy that has to be used on scaled technologies requires a careful control of the experimental tests, preventing spurious second-order effects to emerge. In particular, long gate-stresses required to gather the array threshold voltage (V T ) map are shown to give rise to parasitic V T -drifts, which add to the V T -loss coming from damage recovery during post-cycling bake. When the superposition of the two phenomena is taken into account, the effectiveness of the conventional qualification schemes relying on a 1.1 eV activation energy is fully confirmed at the 45 nm NOR node.

A multiplex dipstick immunoassay based method for the simultaneous determination of major Fusarium toxins, namely zearalenone, T-2 and HT-2 toxins, deoxynivalenol and fumonisins in wheat, oats and maize has been developed. The dipstick format was based on an indirect competitive approach. Four test lines (mycotoxin-BSA conjugates) and one control line were located on the strip membrane. Labelled antibodies were freeze-dried within the microwell. Two matrix-related sample preparation protocols have been developed for wheat/oats (not containing fumonisins) and maize (containing fumonisins) respectively. The use of a methanol/water mixture for sample preparation allowed recoveries in the range 73-109% for all mycotoxins in all tested cereals, with relative standard deviation less than 10%. The optimized immunoassay was able to detect target mycotoxins at cut off levels equal to 80% of EU maximum permitted levels, i.e. 280, 400, 1400 and 3200 μg kg(-1), respectively, for zearalenone, T-2/HT-2 toxins, deoxynivalenol and fumonisins in maize, and 80, 400 and 1400 μg kg(-1), respectively, for zearalenone, T-2/HT-2 toxins and deoxynivalenol in wheat and oats. Analysis of naturally contaminated samples resulted in a good agreement between multiplex dipstick and validated confirmatory LC-MS/MS. The percentage of false positive results was less than or equal to 13%, whereas no false negative results were obtained. Data on the presence/absence of 6 mycotoxins at levels close to EU regulatory levels were obtained within 30 min. The proposed immunoassay protocol is rapid, inexpensive, easy-to-use and fit for purpose of rapid screening of mycotoxins in cereals.

We investigate atmospheric neutron effects on floating-gate cells in NAND Flash memory devices. Charge loss is shown to occur, particularly at the highest program levels, causing raw bit errors in multilevel cell NAND, but to an extent that does not challenge current mandatory error correction specifications. We discuss the physical mechanisms and analyze scaling trends, which show a rapid increase in sensitivity for decreasing feature size.

The significance of laboratory sample preparation for the determination of two important mycotoxins, ochratoxin A (OTA) and deoxynivalenol (DON), in wheat was investigated by comparing water-slurry mixing and dry-milling procedures. The distribution of OTA and DON in 10 kg samples of naturally contaminated wheat was established by analyzing one hundred 100 g subsamples of each sample. A normal distribution and a good repeatability of DON measurements was observed for both water-slurry mixing (mean 2290 μg/kg, CV 4.6%, median 2290 μg/kg) and dry milling (mean 2310 μg/kg, CV 6.4%, median 2290 μg/kg) procedures. For OTA determinations, reliable results could be obtained only by slurry mixing sample preparation (mean 2.62 μg/kg, CV 4.0%, median 2.62 μg/kg), whereas dry-milling comminution resulted in an inhomogeneous distribution with a high variability (mean 0.83 μg/kg, CV 75.2%, median 0.60 μg/kg) and a positive skewness (2.12). Ad hoc experiments were performed on different size portions of the same sample (10 kg) to assess accuracy and precision of the comminution/homogenization procedures (slurry mixing and dry milling). Very good results were obtained for DON determination with both procedures in terms of accuracy (>98.7% of the “weighted value”) and precision (CV

Ochratoxin A (OTA), a mycotoxin produced by Aspergillus and Penicillium species, is composed of a dihydroisocoumarin ring linked to phenylalanine, and its biosynthetic pathway has not yet been completely elucidated. Most of the knowledge regarding the genetic and enzymatic aspects of OTA biosynthesis has been elucidated in Penicillium species. In Aspergillus species, only pks genes involved in the initial steps of the pathway have been partially characterized. In our study, the inactivation of a gene encoding a nonribosomal peptide synthetase (NRPS) in OTA-producing A. carbonarius ITEM 5010 has eliminated the ability of this fungus to produce OTA. This is the first report on the involvement of an nrps gene product in OTA biosynthetic pathway in an Aspergillus species. The absence of OTA and ochratoxin α, the isocoumaric derivative of OTA, and the concomitant increase of ochratoxin β, the dechloro analog of ochratoxin α, were observed in the liquid culture of transformed strain. The data provide the first evidence that the enzymatic step adding phenylalanine to polyketide dihydroisocoumarin precedes the chlorination step to form OTA in A. carbonarius and that ochratoxin α is a product of hydrolysis of OTA, giving an interesting new insight into the biosynthetic pathway of the toxin.

European intake estimates indicate that the presence of HT-2 and T-2 toxins in cereals, mainly in oats, can be of concern for human health. Therefore, the development of sensitive, rapid and reliable methods for determining these mycotoxins in cereals, in particular oats, has high priority. A rapid ultra-performance liquid chromatographic (UPLC) method has been developed for the simultaneous determination of HT-2 and T-2 toxins in oats and wheat at μg kg(-1) level. Ground samples were extracted with methanol/water (90:10, v/v) and the diluted extracts were cleaned up through immunoaffinity columns. HT-2 and T-2 toxins were separated and quantified by UPLC with photodiode array (PDA) detector (λ=202 nm) in less than 5 min. Mean recoveries from blank oats samples spiked with HT-2 and T-2 toxins at levels of 50-1000 μg kg(-1) ranged from 87 to 96%, with relative standard deviations (RSDs) lower than 7%; mean recoveries from wheat spiked with HT-2 and T-2 toxins at levels of 25-100 μg kg(-1) ranged from 91 to 103%, with RSDs lower than 5%. The limit of detection of the method was 8 μg kg(-1) for both toxins (signal-to-noise ratio 3:1). The method was successfully applied to the analysis of HT-2 and T-2 toxins in naturally contaminated oats and wheat samples. A good correlation was found by comparative analysis of naturally contaminated samples of oats (r=0.9985) and wheat (r=0.9058) using the proposed method or a reliable HPLC method with fluorescence detection after pre-column derivatization with 1-anthroylnitrile.

Acuminatopyrone, a recently described metabolite of Fusarium acuminatum was shown to be produced by several strains of Fusarium chlamydosporum and F. tricinctus isolated from various substrates in different countries. The structure of acuminatopyrone has been revised on the basis of NOEDIF and HETCOR nmr experiments, and shown to be 4-methoxy-7,8-dimethyl-2H-pyrano[4,3-b]pyridin-2-one. This structure is biosynthetically consistent with that of chlamydosporol and related compounds that are produced by the same fungal species

A novel compound, trivially named visoltricin, has been isolated from cultures of Fusarium tricinctum on corn. Its structure has been established by chemical reactions and spectroscopic methods (UV, IR, MS, 1 H NMR, and 13 C NMR) as 3- [1-methyl-4-(3-methyl-2-butenyl)imidazol-5-yl]-2-propenoic acid methyl ester (molecular formula C 13 H 18 N 2 O 2 ; molecular weight 234.297). It is the first imidazole derivative produced by a Fusarium species. About 30% of the tested isolates (33) of F. tricinctum from various substrates and geographic areas produced visoltricin when grown on corn. None of the 14 isolates tested from the United States produced the compound

A liquid chromatographic method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn-based foods for infants and young children was subjected to an interlaboratory validation study involving 11 laboratories. Five blind duplicate sample pairs of each matrix were analyzed to establish the accuracy, repeatability, and reproducibility of the method. Mass fractions in the baby food samples ranged from 89.1 to 384.4 microg/kg FB1 and from 22.5 to 73.6 microg/kg FB2. The method involved a warm extraction with citrate phosphate buffer-methanol-acetonitrile (50 + 25 + 25, v/v/v), a cleanup through an immunoaffinity column, and an end-determination of fumonisins by LC after automated precolumn derivatization with o-phthaldialdehyde reagent. RSDs for within-laboratory repeatability (RSDr) ranged from 6.8 to 23.5% for FB1 and 7.6 to 22.9% for FB2. RSDs for between-laboratory reproducibility (RSDR) ranged from 15.4 to 26.2% for FB1 and 21.6 to 36.3% for FB2. Mean FB1 recoveries from baby foods spiked at 100.0 and 250.0 microg/kg were 89 and 96%, respectively; for FB2 spiked foods at 25.0 and 62.5 microg/kg recoveries were 90 and 85%, respectively. HorRat values ranged from 0.8 to 1.2 for FB1, whereas for FB2 they ranged from 0.9 to 1.4 when calculated according to Horwitz, and from 1.0 to 1.7 when calculated according to Thompson, indicating an acceptable among-laboratory precision for all matrixes (HorRat values2).

A sensitive and robust liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the simultaneous determination of aflatoxins (B(1), B(2), G(1), G(2)), ochratoxin A, deoxynivalenol, zearalenone, T-2 and HT-2 toxins in cereal-based foods. Samples were extracted with a mixture of acetonitrile/water (84:16, v/v) and cleaned up through a polymeric solid-phase extraction column. Detection and quantification of the nine mycotoxins were performed by reversed-phase liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS), using fully (13)C-isotope-labelled mycotoxins as internal standards. The method was validated in-house for five different cereal processed products, namely barley, oat and durum wheat flours, rye- and wheat-based crisp bread. Recoveries and repeatability of the whole analytical procedure were evaluated at contamination levels encompassing the EU maximum permitted levels for each tested mycotoxin. Recoveries ranged from 89 to 108% for deoxynivalenol, from 73 to 114% for aflatoxins, from 85 to 114% for T-2 and HT-2 toxins, from 64 to 97% for zearalenone, from 74 to 102% for ochratoxin A. Relative standard deviations were less than 16% for all tested mycotoxins and matrices. Limits of detection (signal-to-noise ratio 3:1) ranged from 0.1 to 59.2 µg/kg. The trueness of the results obtained by the proposed method was demonstrated by analysis of reference materials for aflatoxins, deoxynivalenol, zearalenone. The use of inexpensive clean-up cartridges and the increasing availability of less expensive LC/MS/MS instrumentation strengthen the potential of the proposed method for its effective application for reliable routine analysis to assess compliance of tested cereal products with current regulation.

We investigate the effects of X-ray exposure in 41-nm single level NAND Flash memories at small doses, comparable to those used in printed circuit board inspections. We analyze both short-term effects, such as cell threshold voltage shifts during irradiation, and retention and endurance performance of devices exposed to x rays. For doses smaller than 1krad(Si), no effect is observed. At higher doses, charge loss is observed after the exposure and a modest read margin degradation is seen during hightemperature retention tests.

The corruption of the information stored in floating gate cells due to heavy-ion strikes is a critical issue for the use of Flash memories in space. In this work we examine how feature size scaling affects the single event upset sensitivity of multi-level floating gate cells with NAND architecture. Both experimental data on heavy-ion irradiation and analytical modeling are used to study how the threshold LET and saturation cross section depend on the cell feature size. A comparison is also carried out between multi-level and single-level floating gate cells.

A rapid fluorescence polarization (FP) immunoassay has been developed for the simultaneous determination of T-2 and HT-2 toxins in naturally contaminated wheat samples. Syntheses of four fluorescein-labelled T-2 or HT-2 toxin tracers were carried out and their binding response with seven monoclonal antibodies was evaluated. The most sensitive antibody-tracer combination was obtained by using an HT-2-specific antibody and a fluorescein-HT-2 tracer. The developed competitive FP immunoassay in solution showed high cross-reactivity for T-2 toxin (CR% = 100%) while a very low CR% for neosolaniol (0.12%) and no cross-reactivity with other mycotoxins frequently occurring in wheat. A rapid extraction procedure using 90% methanol was applied to wheat samples prior to FP immunoassay. The average recovery from spiked wheat samples (50 to 200 μg kg(-1)) was 96% with relative standard deviation generally lower than 8%. A limit of detection of 8 μg kg(-1) for the combined toxins was determined. Comparative analyses of 45 naturally contaminated and spiked wheat samples by both the FP immunoassay and high-performance liquid chromatography/immunoaffinity clean-up showed a good correlation (r = 0.964). These results, combined with the rapidity (10 min) and simplicity of the assay, show that this method is suitable for high throughput screening as well as for quantitative determination of T-2 and HT-2 toxins in wheat.

Flash memories operating in space are subject at the same time to the progressive accumulation of total ionizing dose and to intrinsic aging phenomena. In this work we investigate latent Total Ionizing Dose (TID) effects in 41-nm NAND single level cells that do not display neither floating gate errors nor any apparent kind of degradation after exposure. Retention of irradiated cells is analyzed at room and high temperature as a function of total dose previously received. We found that FG cell retention at room temperature is practically unchanged after a total dose up to 30 krad(Si). On the contrary, TID exposure slightly worsens the cell retention time during high-temperature tests. We attribute this behavior to the removal of compensating electrons from the tunnel oxide at high temperature.

A liquid chromatographic method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn-based foods for infants and young children was subjected to an interlaboratory validation study involving 11 laboratories. Five blind duplicate sample pairs of each matrix were analyzed to establish the accuracy, repeatability, and reproducibility of the method. Mass fractions in the baby food samples ranged from 89.1 to 384.4 μg/kg FB1 and from 22.5 to 73.6 μg/kg FB2. The method involved a warm extraction with citrate phosphate buffer–methanol–acetonitrile (50 + 25 + 25, v/v/v), a cleanup through an immunoaffinity column, and an end-determination of fumonisins by LC after automated precolumn derivatization with-o-phthaldialdehyde reagent. RSDs for within- laboratory repeatability (RSDr) ranged from 6.8 to 23.5% for FB1 and 7.6 to 22.9% for FB2. RSDs for between-laboratory reproducibility (RSDR) ranged from 15.4 to 26.2% for FB1 and 21.6 to 36.3% for FB2. Mean FB1 recoveries from baby foods spiked at 100.0 and 250.0 μg/kg were 89 and 96%, respectively; for FB2 spiked foods at 25.0 and 62.5 μg/kg recoveries were 90 and 85%, respectively. HorRat values ranged from 0.8 to 1.2 for FB1, whereas for FB2 they ranged from 0.9 to 1.4 when calculated according to Horwitz, and from 1.0 to 1.7 when calculated according to Thompson, indicating an acceptable among- laboratory precision for all matrixes (HorRat values

A TaqMan and a SYBR Green real time PCR (rt-PCR) were developed for the reliable identification and quantitative detection of Staphylococcus (S.) aureus strains harbouring the enterotoxin gene cluster (egc) regardless of its variants. Both approaches revealed 100% specificity against a panel of 70 reference strains, including 29 clinical and foodborne S. aureus strains harbouring all the egc variants to date known, 4 egc⁻S. aureus strains and 37 strains of phylogenetically closely and distantly related species. Standard curves made by 10 fold dilutions of either genomic DNA or cells from an egc(+)S. aureus log-phase broth culture showed a good linearity of response (R²≥0.993) for six orders of magnitude, with about 100% relative accuracy and a low inter-assay variability (CV≤3.02). The overall limit of quantification (LOQ) for both rt-PCR assays (about 100% PCR efficiency; running time 30 min) was 10 cfu or 10 genome equivalents per reaction mixture although 1 cfu or 1 genome equivalent was detected with a 33.33% probability. These performances were confirmed in raw milk artificially contaminated with log-phase broth cultures of either a single egc(+)S. aureus strain or a mixture of S. aureus strains harbouring all the egc variants to date known. Similar results were also obtained with a raw milk based standard curve of the S. aureus egc(+) mixture in the presence of 10⁶ cfu/mL of egc⁻S. aureus strains harbouring some of the commonest enterotoxin genes associated to the staphylococcal food poisoning. Nonetheless, the TaqMan based approach resulted in a lower sensitivity (LOQ=100 cfu equivalents per reaction mixture) than the SYBR Green based assay (LOQ=10 cfu equivalents per reaction mixture). When applied to real milk samples, both PCR assays provided a good response with 100% diagnostic specificity and 96-107% relative accuracy, as compared to conventional culture-based PCR approaches. Due to the high specificity, the wide dynamic range of detection and the high sensitivity demonstrated even in a complex and potentially highly contaminated raw milk matrix, the SYBR Green rt-PCR assay is a useful diagnostic tool for quick, high throughput and reliable routine screening of egc(+)S. aureus isolates. Moreover, the SYBR Green based quantitative detection of these pathogens in raw milk could remarkably contribute to clarify their actual role in staphylococcal food poisoning and other clinical syndromes associated with the consumption of milk and milk-based products.

An interlaboratory study of the reproducibility characteristics of a liquid chromatographic method for the determination of fumonisins B1 and B2 in corn was conducted in 11 laboratories in the United States, South Africa, Italy, Japan, United Kingdom, and The Netherlands. Each laboratory was supplied with 12 coded, blind duplicates of 6 samples of naturally contaminated corn containing different amounts of fumonisins B1 and B2 . Samples are extracted with methanol-water (3 + 1), extracts are centrifuged, and supernatants are cleaned up on strong-anion-exchange cartridges, which were supplied to participants. Solutions are derivatized with o-phthaldialdehyde, and individual fumonisins are determined by reversed-phase liquid chromatography with fluorescence detection. Quantitation is by comparison with the supplied fumonisin standards. The within-laboratory repeatability was determined by statistical analysis of data after exclusion of outliers. Relative standard deviations for within-laboratory repeatability varied from 7.7 to 25.5% for fumonisin B1 at concentrations between 200 and 2000 ng/g and from 12.5 to 36.8% for fumonisin B2 at concentrations between 70 and 740 ng/g. Relative standard deviations for betweenlaboratory reproducibility varied from 18.0 to 26.7% for fumonisin B1 and from 28.0 to 45.6% for fumonisin B2 at the concentrations mentioned above. These measures of variability indicate that the method is suitable for adoption as an official method provided that the accuracy characteristics are verified collaboratively.

We studied heavy-ion effects on floating gate memories, focusing on the generation of tails in the threshold voltage distributions after irradiation. Using both experiments and simulations based on the Geant4 toolkit, we provide new insight, distinguishing two types of events, large events and small events, which are responsible for the secondary peak and the intermediate region in the post-rad threshold distribution, respectively. Both are well correlated with the energy deposited in the FG. Implications for error rate predictions are discussed.

This letter investigates the impact of control-gate (CG) and floating-gate (FG) doping and geometry on the electron-injection spread (EIS) of nanoscale NAND Flash memories. Doping of CG polysilicon rules the reduction of the CG-to-FG capacitance when moving from the read to the program conditions, as a result of polysilicon depletion. The capacitance reduction is shown, however, to be nearly negligible for the EIS resulting from incremental step pulse programming, which, for the commonly adopted voltage steps, is mainly determined by the capacitance value in read conditions. Finally, the scaling trend of the CG-to-FG capacitance and of the EIS is addressed, discussing the evolution of the FG polysilicon in terms of geometry and dimensions.

An extensive use of Weissella (W.) confusa is currently being made for the production of a variety of fermented foods and beverages although some strains of this species have emerged as opportunistic pathogens for humans and animals. Nevertheless, no rapid methods are available for the reliable identification of W. confusa. We developed a novel PCR using AFLP (Amplified Fragment Length Polymorphism)-derived primers for the rapid and unequivocal identification of W. confusa. Fluorescent AFLP of 30 strains of W. confusa, Leuconostoc citreum, Lactobacillus (Lb.) brevis, Lb. rossiae, Lb. plantarum and Lb. buchneri allowed us to detect, purify and sequence several W. confusa specific AFLP fragments. The homology search in BLAST of a 303 bp nucleotide sequence revealed a ≤ 77% identity of the purified fragment with the lepA gene of several lactic acid bacteria. A PCR assay targeting 225 bp of this fragment was developed and tested against the DNA of 109 strains, including 34 foodborne and clinical W. confusa and 75 strains of 47 phylogenetically closely and distantly related species, resulting in 100% specificity with a detection limit of 16 pg. Being the first species-specific PCR to date developed for the rapid and unambiguous identification of W. confusa, this novel assay could be a reliable and efficient tool for detecting W. confusa not only in food and beverages, but also in clinical specimens, thus contributing to clarify its real significance in human and animal infections.

International audience; The potential risk of exposure to fumonisin B2 (FB2 ) in the grape-wine chain has been recently pointed out after reporting Aspergillus niger in grapes and its ability to produce FB2 and FB4. The occurrence of these two fumonisins in wine was investigated by LC/MS/MS in fifty-one market samples (45 red, 5 white and one rosè wine) produced in various Italian regions. Nine samples of red wine were found contaminated by fumonisin B2 at levels ranging from 0.4 to 2.4 ng/mL, while FB4 was not detected in any of the tested samples. This is the first report on the natural occurrence of FB2 in wine indicating that, although al low levels, there is a real risk of FB2 exposure for the wine-consumer.

Electronic chips working in the space environment are constantly subject to both single event and total ionizing dose effects. To emulate this scenario for Flash memories, we tested under heavy ions floating gate cells, previously irradiated with x-rays, without performing any erase and program operation in between the two exposures. We observed an increase in the heavy-ion upset cross section in the devices that were submitted to TID irradiations, especially at low LETs. This effect is attributed to the combination of the threshold voltage shifts induced by heavy ions and x-rays. Implications for the hardness assurance of Flash memories are discussed.

This paper presents a detailed experimental investigation of the cycling-induced threshold voltage instability of deca-nanometer NAND Flash arrays, focusing on its dependence on cycling time and temperature. When the array is brought to a programmed state after cycling, instability mainly shows up as a negative shift of its threshold voltage cumulative distribution, increasing with time and resulting from partial recovery of cell damage created in the previous cycling period. The threshold voltage loss displays a strong dependence not only on the tunnel oxide electric field during retention, but also on the cycling conditions. In particular, performing cycling over a longer time interval or at higher temperatures delays the threshold voltage transients on the logarithmic time axis. The delay factor is studied as a function of the cycling duration and temperature on 60 and 41 nm technologies, extracting the parameter values required for a universal damage-recovery metric for NAND.

A method for the determination of fumonisin B1 (FB1) and B2 (FB2) in different commercial maize-based products for infants and young children was developed and tested in a limited validation study involving 3 laboratories. The method used extraction at 55 °C with an acidic mixture of methanol-acetonitrile-phosphate/citrate buffer, clean-up through immunoaffinity column and fumonisin determination by high performance liquid chromatography with automated pre-column derivatisation with o-phthaldialdehyde. Recovery experiments were performed at five spiking levels in the ranges of 80-800 µg/kg FB1 and 20-200 µg/kg FB2. Mean recoveries ranged from 83 to 97% for FB1 and from 61 to 78% for FB2. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 5 to 12% for FB1 and from 8 to 13% for FB2, whereas relative standard deviation for between-laboratory reproducibility (RSDR) ranged from 6 to 10% for FB1 and from 9 to 16% for FB2. The limit of quantification of the method (signal to noise ratio of 6) was 2.8 µg/kg for FB1 and 2.2 µg/kg for FB2. Fumonisins were found in 6 out of 19 maize-based baby foods obtained from the Italian retail market at levels up to 53 µg/kg.

This paper presents a new cell crosstalk effect in deca-nanometer nand Flash memories, making the data retention and erase transients of fresh cells dependent on the threshold-voltage level at which adjacent cells in the array are placed. In particular, a programmed cell is shown to display a larger threshold-voltage loss when its adjacent cells are in the erased than in the programmed state, with cells on the same bit line and word line having a similar impact on the acceleration of the threshold-voltage loss. The effect is explained by means of 3-D TCAD simulations, showing that a low threshold voltage for the adjacent cells increases the discharging tunneling current of the monitored cell for a fixed negative potential of its floating gate. This is due to a change of the electric field profile at the corners of the monitored cell active area when the potential of the floating gate of its neighboring cells is modified.

This letter presents a comparison of two different variability sources for data retention of nanoscale NAND Flash memories: the neutral threshold-voltage spread and the electron-emission statistics from the floating gate. Referring to fresh cells programmed to the same threshold-voltage level, the effect of the previous dispersion contributions on the data retention transients of a memory array is evaluated. Both effects are shown to result into a broadening of the array threshold-voltage distribution with time, but a quantitative assessment clearly shows that the neutral threshold-voltage spread dominates over the electron-emission spread, revealing that cell-to-cell parameter variations represent the major source of variability for data retention in nanoscale NAND Flash memories.

We investigate atmospheric neutron effects on floating gate cells in MLC NAND Flash memories. Loss of information is shown to occur especially at the highest program levels, but to an extent that does not challenge current error correction capabilities. We discuss the physical mechanisms and analyze scaling trends, which show a rapid increase in sensitivity for decreasing feature size. A large spread in the cross section is visible from vendor to vendor for comparable feature size. © 2010 IEEE.

Three new enniatins, B 2 , B 3 , and B 4 , were isolated from the hexane extracts of liquid cultures of Fusarium acuminatum MRC 3308, in addition to the four known enniatins, A, A 1 , B, and B 1 . The different enniatins were purified by reversed-phase semipreparative HPLC and could be detected directly in the extracts by FAB-MS or GC/MS. Enniatin B 2 was characterized as N-demethylenniatin B by its NMR, IR, and mass spectra

A survey, carried out in Southern Italy on fungi colonizing oilseed rape (Brassicae napua L subspoleifera DC) in the field, showedAlternaria alternata (Fries) Keissler as one of the predominant species. 11 strains ofAlternaria alternata isolated from oilseed rape were cultured on rice to test the ability to produce mycotoxins. All strains produced mycotoxins, including tenuazonic acid (up to 12,000mg/kg), alternariol (up to 200mg/kg), alternariol mortomethyl ether (up to 200mg/kg), altertoxin-l (2 to 250mg/kg), and altertoxin-ll (2 to 70mg/kg). Culture extracts containing tenuazonic acid were toxic toArtemia salina and inhibited seedling growth of oilseed rape. Little or no activity with the same bioassays was shown by culture extracts containing the remaining mycotoxins. No mycotoxins were detected in 16 samples of oilseed rape from processing factories.

We discuss the room temperature annealing of Floating Gate errors in Flash memories with NAND and NOR architecture after heavy-ion irradiation. We present the evolution of rough bit errors as a function of time after the exposure, examining the annealing dependence on the particle LET, cell feature size, and for Multi Level Cells, on the program level. The results are explained based on the statistical properties of the cell threshold voltage distributions before and after heavy-ion strikes.

A fluorescence polarization (FP) immunoassay, based on a monoclonal antibody and an ochratoxin A (OTA)-fluorescein tracer, has been developed for rapid screening of OTA in red wine. Wine samples were diluted with methanol and passed through aminopropyl solid-phase extraction columns prior to the FP assay. Average recoveries from samples spiked with OTA at levels of 2.0 and 5.0 ng/mL were 79% with RDS of 11% (n = 6). The limit of detection of the FP immunoassay was 0.7 ng/mL OTA, and the whole analysis was performed in less than 10 min. The assay was tested on 154 red wine samples (naturally contaminated or spiked at level ranging from 0.1 to 5.0 ng/mL) and compared with an high-performance liquid chromatography/immunoaffinity column clean-up method, showing a good correlation (r = 0.9222). Their compliance with the European regulation (2.0 ng/mL OTA maximum permitted level) was correctly assessed for 70% of the analyzed samples of red wine, whereas confirmatory analyses were required for the remaining ones with OTA levels close to the regulatory limit. No false-negative or positive results were observed using the FP immunoassay. The proposed FP assay is a useful screening method for OTA in red wines, when high throughput is required, that could also be used for white and rose wines, which are known to contain less interfering compounds such as polyphenols.

The effectiveness of seven phenolic compounds (esculetin, ferulic acid, quercetin, resveratrol, scopoletin, scoparone and umbelliferone) in controlling Penicillium expansum growth and patulin accumulation was evaluated by both in vitro and in vivo studies. The in vitro screening showed that quercetin and umbelliferone were the most effective compounds in controlling Penicillium growth and patulin accumulation, respectively. Quercetin and umbelliferone, resulted to be effective also in the in vivo screening, were further tested (alone and in combination) on Granny Smith and Golden Delicious apples. The efficacy in controlling Penicillium growth was better expressed on Golden Delicious than on Granny Smith apples, with quercetin providing a better control of both incidence of decay and disease severity as compared to umbelliferone. Both compounds exerted a considerable control of patulin accumulation on the two apple cultivars. Quercetin and umbelliferone can be considered as natural compounds to be used as alternative strategy to chemical fungicides in postharvest control of P. expansum infections on apples.

We discuss new experimental results on the post-radiation annealing of Floating Gate errors in Flash memories with both NAND and NOR architecture. We investigate the dependence of annealing on the program level, linking the reduction in the number of Floating Gate errors to the evolution of the threshold voltage of each single cell. To understand the underlying physics we also discuss how temperature affects the number of Floating Gate errors.

The selective enzymatic deacetylation of T-2 toxin to give HT-2 toxin has been investigated in aqueous crude extracts of different cereals and exploited to develop an analytical method for the determination of the sum of T-2 and HT-2 toxins. The method has been validated for the analysis of total T-2 and HT-2 toxins in maize, wheat, and oats, showing recoveries from 72 to 97% for maize, from 67 to 84% for wheat, and from 61% to 87% for oats, at spiking levels of 20-400 microg/kg, with relative standard deviation lower than 10%. Liquid chromatography-tandem mass spectrometry was used for quantitative toxin determination. The potential biological role of this enzymatic conversion and its perspectives for application in the development of antibody-based analytical techniques are discussed.

This work investigates for the first time chargegranularity effects during channel hot-electron programming of NOR Flash memories, comparing the granular electron injection and the random telegraph noise limitations to the accuracy of the programming algorithm. The spread of the threshold voltage shift that is determined by the electron injection statistics is studied as a function of the channel hot-electron programming conditions, explaining the results by an analytical model accounting for the sub-poissonian nature of the electron transfer to the floating gate. The scaling trend of the injection statistical spread is then investigated on NOR technologies ranging from 180 to 45 nm and its contribution to the width of the threshold voltage distribution in presence of a program verify level is separated from that given by random telegraph noise.

This letter presents a detailed investigation of the random telegraph noise (RTN) effects on the threshold-voltage distribution of flash memory arrays programmed by the staircase algorithm. RTN is shown to introduce an exponential tail above the program verify level when considering the cell threshold voltage that ends the program operation. In addition, when a subsequent read operation is considered, a clear exponential tail is shown to appear even below the program verify level. We present a simple analysis that is able to predict the threshold-voltage distribution width accounting for both these enlargement contributions, defining practical formulas for the programming accuracy as a function of the staircase step amplitude and the RTN distribution.

Atmospheric neutrons can interact with the matter inside a microelectronic chip and generate ionizing particles, which in turn can change the state of one or more memory bits [soft error (SE)]. In this letter, we show that SEs are possible in Flash memories, although with extremely low probabilities. While this problem will increase for future technologies, we do not expect SEs to be the reliability limiting factor for further floating gate scaling.

A liquid chromatographic method for the determination of ochratoxin A in grapes, dried vine fruits, and winery byproducts was developed. A mixture of either acetonitrile/water or acetonitrile/water/methanol was used as an extraction solvent mixture. After immunoaffinity column cleanup, the final extract was analyzed by high-performance liquid chromatography (HPLC) with a fluorometric detector (FLD). Mean recoveries from grapes, grape pomace, and lees samples spiked in the range of 1-200 microg/kg were 78, 86, and 88%, respectively, with a detection limit of 0.1 microg/kg and within-laboratory repeatability ranging from 6 to 15%. Tested on naturally contaminated samples of grapes, grape pomace, and sultanas, the method showed better performances as compared to two other methods also based on immunoaffinity cleanup and HPLC/FLD determination. Ochratoxin A was detected in samples of grape pomace (levels ranging from 34.2 to 456.8 microg/kg) and lees (levels ranging from 48.3 to 602.5 microg/kg) derived from the wine making of red grapes of 2004 and 2005 vintages in southern Italy. After distillation of contaminated grape pomace in a pilot-scale equipment to produce grappa, the toxin remained unchanged in the exhausted pomace and was not detected in any of the distilled fractions (detection limit of 0.02 microg/L).

Single, high energy, high LET, ions impacting on a Floating gate array at grazing or near-grazing angles lead to the creation of long traces of FGs with corrupted information. Every time a FG is crossed by a single ion, it experiences a charge loss which permanently degrades the stored information. If the ion crosses more than one FG, the threshold voltage of all those FGs interested by its track will be degraded.

Field experiments in the high rainfall zone (HRZ) and the medium rainfall zone (MRZ) in Zambia were designed to determine the natural occurrence of fumonisins (FB(1-2)) in Zambian maize hybrids, accumulation of FB(1-2) resulting from artificial inoculation with Fusarium verticillioides and effects of climate and planting time on FB(1-2) in maize. Combined FB(1-2) concentrations varied from 0 to 13,050 ng/g, with an overall mean of 666 ng/g. Maize from the HRZ had low incidences of FB(1-2)-positive samples (mean 41%) which contained FB(1-2) below 500 ng/g. In the MRZ, higher incidences (mean 97%) and concentrations (40% of samples1,000 ng/g) were recorded in two out of three years. There was no correlation between mean location FB(1-2) concentrations in individual years and precipitation, number of rain days or monthly precipitation. Postponing the planting time with 10 or 20 days did not significantly affect FB(1-2) concentration, but it reduced the yields in some years.

Zearalenone (ZEA) is a fusariotoxin naturally occurring in crops with known estrogenic activity in swine, the most sensitive known species. The metabolism by swine of ZEA, principally into alpha-zearalenol (alpha-ZOL), is considered as a bio-activation because of its high affinity with estrogenic receptors. Discordant data on male reproductive failures induced by ZEA in vivo are described. In this study, we evaluated the effects to boar spermatozoa when they are exposed in vitro to ZEA and its derivatives (alpha-ZOL, beta-ZOL). We analyzed viability, apoptosis (terminal deoxynucleotidyltransferase dUTP nick end-labelling (TUNEL)), sperm chromatin stability (sperm chromatin structure assay (SCSA)) and motility (using computer-aided sperm analysis (CASA)). Each mycotoxin influenced a specific function of spermatic cells. alpha-Zearalenol and ZEA, at picomolar levels, negatively influenced chromatin structure stability and viability, respectively, whereas beta-ZOL negatively influenced the sperm motility at micromolar levels. This study is the first using these direct measures of sperm integrity to show the potential for an adverse effect of ZEA exposure on boar fertility.

This paper presents an analytical investigation of the spatial and energetic position of the traps responsible for threshold voltage random telegraph fluctuations in a metal-oxide-semiconductor device. Assuming a stationary trap-filling condition as a result of the application of a constant gate bias, a simple formula is obtained to identify the oxide region where traps having an arbitrary probability to change their state between two subsequent time instants are located. Results are extremely important for the statistical spectroscopic analysis of random telegraph noise sources.

We present a detailed analytical modeling for the constant-current Fowler-Nordheim program operation of NAND flash memories, able to describe both the average transient of the cell threshold voltage and its statistical spread due to the granular nature of the electron current flowing through the cell tunnel oxide. We analytically investigate the electron-injection process, highlighting that the steepness of the tunneling current versus floating-gate voltage characteristics and the control-gate to floating-gate capacitance give the field feedback factor, determining the average number of injected electrons at which the injection process becomes sub-Poissonian. Finally, we show that cell scaling will reduce the achievable accuracy of the program algorithm, due to the reduction in the number of electrons controlling cell state.

We present a thorough investigation of the random telegraph noise scaling trend for both NAND and NOR floating-gate flash memories, including experimental and physics-based modeling results. The statistical distribution of the random telegraph noise amplitude is computed using conventional 3D TCAD simulations, establishing a direct connection with cell parameters. The analysis results in a simple formula for the random telegraph noise amplitude standard deviation as a function of cell width, length, substrate doping, tunnel oxide thickness and drain bias. All the simulation results are in good agreement with experimental data and are of utmost importance to understand the random telegraph noise instability and to control it in the development of next generation flash technologies.