Total HCN Research Articles

Interneuron-selective HCN channel knockdown in prelimbic cortex of female rats mimics effects of chronic ethanol exposure

Our laboratory has previously shown that chronic ethanol exposure elicits enhanced working memory performance in female, but not male, adult Sprague–Dawley rats, indicative of a fundamental sex difference in cortical plasticity. Recent studies have furthermore revealed that females display markedly reduced HCN-mediated channel activity in inhibitory Martinotti interneurons after chronic ethanol exposure that is similarly not observed in males. From these observations we hypothesized that alcohol induces facilitated working memory performance via down-regulation of these channels’ activity specifically within interneurons. To test this hypothesis, we employed a Pol-II compatible shRNA expression system to elicit targeted knockdown of HCN channel activity in these cells, and measured performance on a delayed Non-Match-to-Sample (NMS) T-maze test to gauge effects on working memory performance. A significant baseline enhancement of working memory performance with HCN channel knockdown was observed, indicative of a critical role for interneuron-expressed HCNs in maintaining optimal cortical network activity during cognitively-demanding tasks. Consistent with previous observations, ethanol exposure resulted in enhanced NMS T-maze performance, however elevated working memory performance was observed in both scram- and hcn-shRNA infected groups after alcohol administration. We therefore conclude that interneuron-expressed HCN channels, despite representing a minor population of total cortical HCN expression, contribute substantially to maintaining working memory processes. Downregulated HCN channel activity, though, does not alone appear sufficient to manifest alcohol-induced enhancement of working memory performance observed in female rats during acute withdrawal.

Total and Free Hydrogen Cyanide Content and Profile of Bioactive Amines in Commercial Tucupi, a Traditionally Derived Cassava Product Widely Consumed in Northern Brazil.

Tucupi is a broth derived from cassava roots which is produced after the spontaneous fermentation of manipueira (the liquid portion obtained by pressing cassava roots), followed by cooking. This product is widely consumed along with traditional dishes in the Brazilian Amazonia and is already used in different places worldwide. In this study, tucupi obtained from the markets of Belém (Pará, Brazil) and produced using agroindustrial (11 samples) and non-agroindustrial (11 samples) units were investigated to determine their physicochemical characteristics, total and free HCN contents, and free bioactive amine profiles. Most of the samples showed significant variations (p ≤ 0.05) in pH (2.82-4.67), total acidity (0.14-1.36 g lactic acid/100 mL), reducing sugars (up to 2.33 g/100 mL), and total sugars (up to 4.35 g/100 mL). Regarding the amines, four biogenic amines (0.5-4.2 mg/L tyramine, 1.0-23.1 mg/L putrescine, 0.5-66.8 mg/L histamine, and 0.6-2.9 mg/L tryptamine) and one polyamine (0.4-1.7 mg/L spermidine) were identified in the tucupi samples. Even in the tucupi produced using the agroindustrial units, which had quality seals provided by the local regulatory agency, high levels of biogenic amines (4.4-78.2 mg/L) were observed, as well as high dosages of total (8.87-114.66 mg/L) and free (0.80-38.38 mg/L) HCN. These facts highlight the need for better knowledge regarding the product manufacturing process to establish standardization and high-quality conditions for tucupi processing since high contents of biogenic amines and HCN are commonly associated with adverse health effects.

HCN emission from translucent gas and UV-illuminated cloud edges revealed by wide-field IRAM 30 m maps of the Orion B GMC

Context. Massive stars form within dense clumps inside giant molecular clouds (GMCs). Finding appropriate chemical tracers of the dense gas (n(H2) > several 104 cm−3 or AV > 8 mag) and linking their line luminosity with the star formation rate is of critical importance. Aims. Our aim is to determine the origin and physical conditions of the HCN-emitting gas and study their relation to those of other molecules. Methods. In the context of the IRAM 30m ORION-B large program, we present 5 deg2 (~250 pc2) HCN, HNC, HCO+, and CO J =1–0 maps of the Orion B GMC, complemented with existing wide-field [C I] 492 GHz maps, as well as new pointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines. We compare the observed HCN line intensities with radiative transfer models including line overlap effects and electron excitation. Furthermore, we study the HCN/HNC isomeric abundance ratio with updated photochemical models. Results. We spectroscopically resolve the HCN J = 1–0 hyperfine structure (HFS) components (and partially resolved J = 2−1 and 3−2 components). We detect anomalous HFS line intensity (and line width) ratios almost everywhere in the cloud. About 70% of the total HCN J = 1−0 luminosity, L′(HCN J = 1−0) = 110 K km s−1 pc−2, arises from AV < 8 mag. The HCN/CO J = 1−0 line intensity ratio, widely used as a tracer of the dense gas fraction, shows a bimodal behavior with an inflection point at AV < 3 mag typical of translucent gas and illuminated cloud edges. We find that most of the HCN J = 1−0 emission arises from extended gas with n(H2) < 104 cm−3, and even lower density gas if the ionization fraction is χe ≥ 10−5 and electron excitation dominates. This result contrasts with the prevailing view of HCN J = 1−0 emission as a tracer of dense gas and explains the low-AV branch of the HCN/CO J = 1−0 intensity ratio distribution. Indeed, the highest HCN/CO ratios (~ 0.1) at AV < 3 mag correspond to regions of high [C I] 492 GHz/CO J = 1−0 intensity ratios (>1) characteristic of low-density photodissociation regions. The low surface brightness (≲ 1 K km s−1) and extended HCN and HCO+ J = 1−0 emission scale with IFIR – a proxy of the stellar far-ultraviolet (FUV) radiation field – in a similar way. Together with CO J = 1−0, these lines respond to increasing IFIR up to G0 ≃ 20. On the other hand, the bright HCN J = 1−0 emission (> 6 K km s−1) from dense gas in star-forming clumps weakly responds to IFIR once the FUV field becomes too intense (G0 > 1500). In contrast, HNC J = 1−0 and [C I] 492 GHz lines weakly respond to IFIR for all G0. The different power law scalings (produced by different chemistries, densities, and line excitation regimes) in a single but spatially resolved GMC resemble the variety of Kennicutt-Schmidt law indexes found in galaxy averages. Conclusions. Given the widespread and extended nature of the [C I] 492 GHz emission, as well as its spatial correlation with that of HCO+, HCN, and 13CO J = 1−0 lines (in this order), we argue that the edges of GMCs are porous to FUV radiation from nearby massive stars. Enhanced FUV radiation favors the formation and excitation of HCN on large scales, not only in dense star-forming clumps, and it leads to a relatively low value of the dense gas mass to total luminosity ratio, α (HCN) = 29 M⊙/(K km s−1pc2) in Orion B. As a corollary for extragalactic studies, we conclude that high HCN/CO J = 1−0 line intensity ratios do not always imply the presence of dense gas, which may be better traced by HNC than by HCN.

Experimental Evidence for Alloying Effects in Au–Pt-Catalyzed Low-Temperature CH4Activation with NO

The activation of methane with nitric oxide at low temperatures (300–400 °C) and atmospheric pressure was studied on Au–Pt nanoparticles with different Au/Pt ratios supported on alumina. The reaction forms HCN, a valuable chemical intermediate, via concurrent or successive C–H bond cleavage, NO dissociation, and C–N coupling reactions. The catalysts with different Au/Pt ratios had similar particle morphology and bulk properties, as evidenced by scanning transmission electron microscopy imaging and X-ray absorption near-edge structure spectroscopy, respectively. However, they exhibited different electronic and geometric surface properties, according to in situ diffuse reflectance infrared Fourier transform spectra of preadsorbed CO, a likely consequence of Au surface enrichment. These differences had catalytic implications, where the relative proportion of electron-deficient Pt sites on the surface of the catalysts was found to track with activity, expressed as turnover frequency for the total CH4 conversion and HCN formation. Based on the activity trend, kinetic comparison of reaction orders, temperature-programmed desorption experiments, and comparisons to the literature, it is proposed that the CH4–NO catalysis occurred mainly on contiguous Pt sites, that the higher C–H activation activity of electron-deficient Pt species may be related to weaker adsorption of CH4, and that the higher NO dissociation activity of metallic Pt species may have contributed to the complete oxidation of CH4 to CO2. Nonetheless, contact time and in situ spectroscopic studies at isothermal conditions revealed only subtle differences in the reaction scheme by surface modifications, indicating that Au affected the reactivity indirectly.

Genetic analysis using Griffing’s approach for forage yield and components in sorghum

The present study was carried out using seven parental lines including check CSV 46F and their 21 diallel crosses, excluding reciprocal. The experiment was evaluated in randomised block design with three replications during Kharif 2021 at the Centre for Millets Research, Sardarkrushinagar Dantiwada Agricultural University, Deesa. The analysis of variance (mean sum of squares) revealed significant differences for the genotypes, parents, hybrids and parents vs. hybrids among most of the characters, which explained a sufficient amount of heterosis and was reflected in crosses for fodder yield and its attributing characters. The parents SH 1488 and DS 200 recorded maximum mean performance for green forage yield and dry fodder yield per plant. The result of ANOVA for combining ability revealed that the mean sum of squares due to GCA and SCA were found highly significant for studied characters. The ratio ( 2GCA/ 2SCA) of variances for various characters bare standing of non-additive gene action type in the appearance of forage yield and supporting characters. The parent CSV 21F was found to be a good general combiner for green fodder yield per plant. While, parents SH 1488, DS 200 and CSV 21F were found to be good general combiners for dry fodder yield. The parent SSG 59-3 was a very good general combiner for days to flowering, total plant height, stem diameter, crude protein and HCN content. The crosses S 652 × CSV 46F, DS 200 × CSV 21F and SSG 59-3 × S 652 for green fodder yield per plant, while SSG 59-3 × S 652, DS 200 × CSV 21F and SSG 59-3 × CSV 46F for dry fodder yield per plant recorded the highest sca effects. Based on all the genetic parameters, the crosses SSG 59-3 × S 652, SH 1488 × S 652, SH 1488 × DSF 182 and DS 200 × CSV 21F with high mean performance, high sca effects and at least one parent having good to moderate gca effects would increase the frequency of favourable alleles. Therefore, it may be hopeful to select good homozygous lines to ameliorate respective characters in forage sorghum. It can also be used directly in varietal breeding programmes. Keywords: Forage sorghum, Heterosis, GCA, SCA and forage yield.

Functionalizing Ti3C2Tx for enhancing fire resistance and reducing toxic gases of flexible polyurethane foam composites with reinforced mechanical properties

Flexible polyurethane foam (FPUF) is the most used polyurethane, but the highly flammable characteristic limits its widespread usage. In this work, ZIF-8@Ti3C2Txwas synthesized to reduce the heat and toxic gases of FPUF. Flame-retardant FPUF was characterized by cone calorimeter (Cone), thermogravimetric analysis/fourier-transform infrared spectroscopy (TG-FTIR), tensileand compression tests. Compared with pure FPUF, these results showed that the peak of heat release rate (PHRR), total heat release (THR), CO and HCN of FPUF6 decreased by 46%, 69%, 27% and 43.5%, respectively. Moreover, the tensile and compression strength of FPUF6 demonstrated a 52% and 130% increment, respectively. The superior dual metal catalytical charring-forming effect and physical barrier effect of ZIF-8@Ti3C2Tx were achieved. In summary, a simple and reliable strategy for preparing flame-retardant FPUF with reinforced mechanical and fire safety properties was provided.

Multifrequency high spectral resolution observations of HCN toward the circumstellar envelope of Y Canum Venaticorum

High spectral resolution observations toward the low mass-loss rate C-rich, J-type asymptotic giant branch (AGB) star Y CVn were carried out at 7.5, 13.1, and 14.0 μm with the Echelon-cross-echelle Spectrograph mounted on the Stratospheric Observatory for Infrared Astronomy and the Texas Echelon-cross-echelle Spectrograph on the Infrared Telescope Facility. Around 130 HCN and H13CN lines of bandsν2, 2ν2, 2ν2−ν2, 3ν2− 2ν2, 3ν2−ν2, and 4ν2− 2ν2were identified involving lower levels with energies up to ≃3900 K. These lines were complemented with the pure rotational linesJ= 1−0 and 3–2 of the vibrational states up to 2ν2acquired with the Institut de Radioastronomie Millimétrique 30 m telescope, and with the continuum taken with Infrared Space Observatory. We analyzed the data in detail by means of a ro-vibrational diagram and with a code written to model the absorption and emission of the circumstellar envelope of an AGB star. The continuum is mostly produced by the star with a small contribution from dust grains comprising warm to hot SiC and cold amorphous carbon. The HCN abundance distribution seems to be anisotropic close to Y CVn and in the outer layers of its envelope. The ejected gas is accelerated up to the terminal velocity (≃8 km s−1) from the photosphere to ≃3R⋆, but there is evidence of higher velocities (≳9–10 km s−1) beyond this region. In the vicinity of the star, the line widths are as high as ≃10 km s−1, which implies a maximum turbulent velocity of 6 km s−1or the existence of other physical mechanisms probably related to matter ejection that involve higher gas expansion velocities than expected. HCN is rotationally and vibrationally out of local thermodynamic equilibrium throughout the whole envelope. It is surprising that a difference of about 1500 K in the rotational temperature at the photosphere is needed to explain the observations at 7.5 and 13–14 μm. Our analysis finds a total HCN column density that ranges from ≃2.1 × 1018to 3.5 × 1018cm−2, an abundance with respect to H2of 3.5 × 10−5to 1.3 × 10−4, and a12C/13C isotopic ratio of ≃2.5 throughout the whole envelope.

Nutritional and phytochemical profiling of nutracereal finger millet (Eleusine coracana L.) genotypes

Finger millet (Eleusine coracana L.) is gaining popularity as healthy food due to its nutritional and phytochemical properties. This study reports nutritional and phytochemical profile of ten finger millet genotypes. Proximate analysis of finger millet genotypes revealed moisture, total carbohydrate, protein, fat, fiber and ash in the range of 7.50–11.75, 71.90–76.38, 6.7–8.0, 1.2–1.7, 3.1–3.8 and 3.1–3.8 per cent respectively. Micro-nutrient profiling showed Ca, Fe, Zn, P, K and Mn in the range of 2400.00–3400.00, 40.28–47.60, 12.40–17.45, 1600.00–2900.00, 3800.00–5200.00 and 51.33–61.28 mg kg−1 respectively. Phytochemical profiling was done for total phenol, phytic acid, tannins, flavonoids, HCN, oxalate and trypsin inhibitor which were observed in the range of 99.75–112.25, 210.75–302.75, 340.00–500.00, 62.23–74.05, 2.45–2.80, 19.80–26.23 mg 100 g−1 and 207.35–234.23 TIU g−1 respectively. Amino acid profiling showed good amount of essential amino acids. Nutritional and phytochemical profiling of finger millet genotypes showed its potentiality to become source of health promoting food.

Oven drying and hot water cooking processes decrease HCN contents of cassava leaves

The aim of this work was to study the effects of temperature and time of oven drying and hot water cooking processes on HCN (hydrocyanic acid) degradation of cassava leaves as a contribution for obtaining a safe product for human consumption. Nine varieties of cassava leaves collected in the Amazonian region of Brazil (Pará State) were characterized regarding moisture, pH, total acidity, ashes, total lipids, total protein, water activity, carbohydrates, total energetic value and HCN contents. The leaves of the three cassava varieties, which presented the highest HCN contents, were submitted to the thermal degradation of HCN, under drying and boiling conditions. All the leaves presented similar physicochemical characteristics and the HCN contents varied from 90.6 to 560.9 mg HCN/kg fresh leaves (total HCN) and from 16.6 to 59.2 mg HCN/kg fresh leaves (free HCN). Thermal degradation studies on HCN showed that the drying and boiling processes were effective on total HCN removal after 180 min. Furthermore, a remarkable decrease in HCN contents was observed after 20 min of boiling. Regarding free HCN, the drying method was more effective than boiling, showing high degradation percentages: 74.1%–92.2% to 1.1%–72.4%, respectively.

Biochemical changes in spiralling whitefly affected cassava leaves and its impact on eri silkworm Samia cynthia ricini boisduval

Changes in the biochemical constituents including nutritional and anti-nutritional values of the cassava varieties H226 and MVD1 infested by spiralling whitefly, Aleurodicus dispersus Russell and its influence on economic traits of eri silkworm Samia cynthia ricini Boisduval were studied. The moisture, crude protein, total carbohydrate, nitrogen, phosphorus, potassium and total minerals, tannins and HCN of leaves of both varieties were drastically reduced following infestation. The larvae fed with infested leaves from both varieties showed significant adverse effect on economic traits i.e. increase in total larval period and reduction in other traits namely larval weight, effective rate of rearing, cocoon yield, shell yield, shell ratio, fecundity and hatchability compared to those of healthy leaves recording lower larval duration and higher values of other corresponding traits. For all parameters adverse effect was more pronounced in the lot fed with infested MVD1 leaf than the variety H226.

Analysis of Chemical Characteristic of Casava Flour from Klenteng and Casessart (UJ5) Varieties

The technology of cassava flour modification has been researched and developed. Biological change by using BIMO-CF containing lactic acid bacteria is a practical technology that is easy to apply in the production of cassava flour. This research was conducted from May until August 2017 at Agrosains Park Natar with the aim to know the chemical characteristics of cassava flour from Klenteng and Casessart varieties. Observation parameters included analysis of moisture content, ash content, fat content, protein content, fiber content, total carbohydrate content, starch content, HCN content, and white degree at THP Polytechnic State Laboratory of Lampung. The results showed that the highest yield was produced by cassava flour from casessart variety with the addition of BIMO-CF were 23.11%. The water content of cassava flour produced ranged between 8.02-9.19%, by the quality requirements of SNI. The lowest ash content was cassava flour from casessart variety (1.19%) without the addition of starter. The addition of starter increased the protein content of cassava flour both of Klenteng variety (0.47%) and Casessart variety (1.11%), decreasing the fiber content for Klenteng variety (0.67%) and Casessart variety (0.90%). The amount of fat contained in cassava flour produced ranged from 0.69 to 0.87%. Carbohydrate content (Klenteng variety was 88.49%, and Casessart variety was 87,69%) and starch content (Klenteng variety was 85,98%, and Casessart variety was 84,83%), cassava flour with the addition of starter higher than cassava flour without the addition of starter. All of the cassava flour produced has HCN levels below the maximum limit (0.0216-0.0293%), while the degree of white (> 80%) has not met the quality requirements of SNI.

Small functional If current in sinoatrial pacemaker cells of the brown trout (Salmo trutta fario) heart despite strong expression of HCN channel transcripts.

Funny current (If), formed by hyperpolarization-activated cyclic nucleotide-gated channels (HCN channels), is supposed to be crucial for the membrane clock regulating the cardiac pacemaker mechanism. We examined the presence and activity of HCN channels in the brown trout (Salmo trutta fario) sinoatrial (SA) pacemaker cells and their putative role in heart rate (fH) regulation. Six HCN transcripts (HCN1, HCN2a, HCN2ba, HCN2bb, HCN3, and HCN4) were expressed in the brown trout heart. The total HCN transcript abundance was 4.0 and 4.9 times higher in SA pacemaker tissue than in atrium and ventricle, respectively. In the SA pacemaker, HCN3 and HCN4 were the main isoforms representing 35.8 ± 2.7 and 25.0 ± 1.5%, respectively, of the total HCN transcripts. Only a small If with a mean current density of -1.2 ± 0.37 pA/pF at -140 mV was found in 4 pacemaker cells out of 16 spontaneously beating cells examined, despite the optimization of recording conditions for If activity. If was not found in any of the 24 atrial myocytes and 21 ventricular myocytes examined. HCN4 coexpressed with the MinK-related peptide 1 (MiRP1) β-subunit in CHO cells generated large If currents. In contrast, HCN3 (+MiRP1) failed to produce If in the same expression system. Cs+ (2 mM), which blocked 84 ± 12% of the native If, reversibly reduced fH 19.2 ± 3.6% of the excised multicellular pacemaker tissue from 53 ± 5 to 44 ± 5 beats/min (P < 0.05). However, this effect was probably due to the reduction of IKr, which was also inhibited (63.5 ± 4.6%) by Cs+ These results strongly suggest that fH regulation in the brown trout heart is largely independent on If.

Chemical Characteristics of Biscuit Substituted by Modified Cassava Product (Mocap) Flour from High Cyanide Variety of Cassava

Cassava ( Manihot esculenta Cranzt) is easily cultivated and an important source of carbohydrates. Currently, only a certain type of low cyanide cassava has been utilized for food product and intermediate product as flour. Processing of high cyanide cassava through submerged and solid-state fermentation simultaneously into mocap (modified cassava product) flour has successfully lowered the cyanide into a safe level for consumption. The application of mocap flour for biscuit is important to know the characteristic changes that occur due to substitution of mocap flour. Variations of wheat flour: mocap flour of 40:60, 30:70, 20:80, 10:90, and 0:100 were used in the preparation of biscuits. The resulting biscuits were analyzed for their chemical characteristics including moisture, protein, fat, starch, amylose, crude fiber, reducing sugars, and cyanide compounds. The cyanide compounds comprised of total cyanide, HCN, and cyanogenic glycosides. Substitution of wheat flour by mocap flour in biscuit making produced the changes of biscuit characteristics. Protein, moisture, starch, amylose, fat, and reducing sugar content was decreased by increasing substitution of mocap flour. Meanwhile, crude fiber and cyanogenic compounds increased by increasing mocap flour substitution. All biscuits with variation of mocap flour substitution were safe to consume because of low level of cyanides.

Cyanide reduction pattern of cassava (mannihot Esculenta) as affected by variety and air velocity using fluidized bed dryer

Detoxification of two cassava varieties (TMS30572 and TMS98/0581) by varying drying temperature and air velocity to produce cassava chips was studied at the Department of Food Science and Technology, Federal University of Technology Akure, Ondo; State Nigeria. Quantitative determination of total cyanide (HCN) in cassava chips was carried out using alkaline titration method. Results show that varieties and air velocity interactions highly significantly reduced (P≤0.05) the total cyanide content in the dried chips. Drying at temperature of 40 oC, air velocity of 2.03 m/s, 2.25 m/s, 2.45 m/s and 2.75 m/s reduced the cyanide content from 8.19 mg/kg to range between 2.53 mg/kg-1.07 mg/kg; at temperature of 50 oC at same air velocity gave result of 4.05 mg/kg-1.63 mg/kg; at temp of 60 oC same set of air velocity gave 6.75 mg/kg-1.01 mg/kg and temperature of 70 oC at same air velocity of 7.08 mg/kg - 1.87 mg/kg for TMS30572. TMS98/0581 at temperature of 40 oC, 50 oC, 60 oC and 70 oC and air velocity of 2.03 m/s, 2.25 m/s, 2.45 m/s and 2.75 m/s gave result of 7.43 mg/kg-3.04 mg/kg; 0.45 mg/kg-0.67 mg/kg;0.68 mg/kg-0.59 mg/kg and 0.59 mg/kg respectively. It was noted that total HCN content in cassava chips can be substantially reduced by drying at temperature of 70 oC and air velocity of 2.75 m/s for TMS30572 and temperature of 60 oC and 70 oC at air velocity of 2.75 m/s. This study shows

A study of nitrogen conversion and polycyclic aromatic hydrocarbon (PAH) emissions during hydrochar–lignite co-pyrolysis

Nitrogen conversion and polycyclic aromatic hydrocarbon (PAH) formation during rapid pyrolysis of hydrochar, lignite and hydrochar–lignite blends have been investigated within a temperature range of 600–900°C. The results showed that in comparison to lignite, a higher percentage of hydrochar nitrogen was retained in the char, and less NH3 and HCN were formed during pyrolysis. During pyrolysis of the individual hydrochar and lignite components, yields of NH3 and HCN reached a maximum at 800°C and then decreased with increasing temperature. Addition of hydrochar to the lignite increased yields of total HCN and NH3 at low pyrolysis temperatures (⩽700°C), but suppressed their formation at high temperatures (⩾800°C). Synergistic interactions in hydrochar–lignite blends significantly decreased the total nitrogen percentage in the char, and promoted the conversion into N2 at temperatures⩾800°C. These synergistic interactions increased with (but were not linearly proportional to) increasing temperatures and hydrochar ratios in the blends. With regard to PAH emissions, relatively less high-ring PAHs were present in tars from pyrolysis of hydrochar–lignite blends than in tars from pyrolysis of lignite alone. These findings suggest that co-processing of hydrochar–lignite blends for energy production may have the additional benefit of reducing emissions of nitrogen pollutants and PAHs.

Assessment of Cyanide Content in Cassava (Manihot esculenta Crantz) Varieties and Derived Products from Senegal

We investigated cyanide levels in four cassava varieties and some derived products from Senegal. The study was conducted on fresh tubers by sampling in three longitudinal positions (1/4; 1/2; 3/4) and four radials (A, B, C and D). In addition, the sampling of derived products was carried out by product types (chip dried, graded, unpressed and pressed attieke, gari and flour). Cyanide contents were determined using differential pulse polarography. Results showed that whatever the variety considered, there was no significant difference between the total HCN content in cassava slices (1/4; 1/2; 3/4). Similarly, results from different layers (A, B, C and D) did not highlight the radial variability of the total HCN content. We showed a variable cyanide content (mg HCN/kg fresh material) in cassava varieties: 104.3 ± 3.9; 171.6 ± 5.4; 231.2 ± 10.2; 270.8 ± 12.0 for Kombo, Nigeria, Soya and Gniargui respectively. The detoxification processes (attieke, gari and flour) indicated a reduction rate in excess of 80% and may be effective to reduce the cyanide content in cassava root down to a tolerable level (< 50 mg/kg).

Soaking and drying of cassava roots reduced cyanogenic potential of three cassava varieties at Jimma, Southwest Ethiopia

Detoxification of three cassava varieties (NR-44/72, NW-45/72 and NW-44/72) by traditional methods of processing to produce cassava flour was investigated at the college of agriculture, Jimma University during February-May, 2007. Total HCN quantitative determination in cassava flour was carried out using a simple enzymatic picrate paper method developed by Dr. Haward Bradbury. Results showed that varieties, soaking time and their interactions highly significantly reduced (P<0.01) total HCN content (ppm) in the flour. Soaking of cassava chips in water for about 24 hours prior to sun drying reduced the HCN from 108.37 to 10.83 ppm (reduced by 90 %), from 66.45 to 13.33 ppm (reduced by 79.94%) and from 58.63 to 15.0 (reduced by 74.42 %) for varieties NW-44/72, NR-44/72 and NW-45/72, respectively. It was noted that total HCN content in cassava flour can be substantially eliminated (by more than 80%) by soaking of cassava chips in water. The present study highlighted the importance of soaking of cassava chips for at least 24 hours prior to sun drying for a safe level of HCN in the flour. However, it is also important to develop new and improved processing techniques to reduce HCN substantially.

Analysis of cyanogens with resorcinol and picrate

The total cyanogenic potential of various substrates (flax seed, stones of peach, plum, nectarine and apricot as well as apple seeds, and various model compounds) was investigated by using the acid hydrolysis method, picrate method, and a novel method based on the reaction of cyanide liberated from plants with resorcinol and picrate. The hydrocyanic acid liberated from cyanogens was trapped by using a 1% sodium bicarbonate. Then, 1 ml of extract was mixed with 1 ml of working reagent containing 160 μg of resorcinol, 320 μg of picric acid, and 30 mg of sodium carbonate, and heated on a boiling water bath for 10 min. The absorbance was measured at 488 nm in 1 cm glass cuvettes at room temperature. The color system obeys Beer’s law in the range of 0–5 μg ml −1 total HCN. Using model compounds and real samples including replicate analyses on prunasin, the resorcinol method proved to be more accurate, reproducible, and especially more sensitive than the known spectrophotometric methods such as the acid hydrolysis method and the picrate method.

On the HCN and CO 2 abundance and distribution in Jupiter's stratosphere

Observations of Jupiter by Cassini/CIRS, acquired during the December 2000 flyby, provide the latitudinal distribution of HCN and CO 2 in Jupiter's stratosphere with unprecedented spatial resolution and coverage. Following up on a preliminary study by Kunde et al. [Kunde, V.G., and 41 colleagues, 2004. Science 305, 1582–1587], the analysis of these observations leads to two unexpected results (i) the total HCN mass in Jupiter's stratosphere in 2000 was ( 6.0 ± 1.5 ) × 10 13 g , i.e., at least three times larger than measured immediately after the Shoemaker–Levy 9 (SL9) impacts in July 1994 and (ii) the latitudinal distributions of HCN and CO 2 are strikingly different: while HCN exhibits a maximum at 45° S and a sharp decrease towards high Southern latitudes, the CO 2 column densities peak over the South Pole. The total CO 2 mass is ( 2.9 ± 1.2 ) × 10 13 g . A possible cause for the HCN mass increase is its production from the photolysis of NH 3, although a problem remains because, while millimeter-wave observations clearly indicate that HCN is currently restricted to submillibar ( ∼ 0.3 mbar ) levels, immediate post-impact infrared observations have suggested that most of the ammonia was present in the lower stratosphere near 20 mbar. HCN appears to be a good atmospheric tracer, with negligible chemical losses. Based on 1-dimensional (latitude) transport models, the HCN distribution is best interpreted as resulting from the combination of a sharp decrease (over an order of magnitude in K y y ) of wave-induced eddy mixing poleward of 40° and an equatorward transport with ∼ 7 cm s −1 velocity. The CO 2 distribution was investigated by coupling the transport model with an elementary chemical model, in which CO 2 is produced from the conversion of water originating either from SL9 or from auroral input. The auroral source does not appear adequate to reproduce the CO 2 peak over the South Pole, as required fluxes are unrealistically high and the shape of the CO 2 bulge is not properly matched. In contrast, the CO 2 distribution can be fit by invoking poleward transport with a ∼ 30 cm s −1 velocity and vigorous eddy mixing ( K y y = 2 × 10 11 cm 2 s −1 ). While the vertical distribution of CO 2 is not measured, the combined HCN and CO 2 results imply that the two species reside at different stratospheric levels. Comparing with the circulation regimes predicted by earlier radiative-dynamical models of Jupiter's stratosphere, and with inferences from the ethane and acetylene stratospheric latitudinal distribution, we suggest that CO 2 lies in the middle stratosphere near or below the 5-mbar level.

The Distribution of H13CN in the Circumstellar Envelope around IRC+10216

H13CN J = 8 → 7 submillimeter line emission produced in the circumstellar envelope around the extreme carbon star IRC+10216 has been imaged at subarcsecond angular resolution using the SMA. Supplemented by a detailed excitation analysis, the average fractional abundance of H13CN in the inner wind (≲5 × 1015 cm) is estimated to be about 4 × 10-7, translating into a total HCN fractional abundance of 2 × 10-5 using the isotopic ratio 12C/13C = 50. Multitransitional single-dish observations further require the H13CN fractional abundance to remain more or less constant in the envelope out to a radius of ≈4 × 1016 cm, where the HCN molecules are effectively destroyed, most probably, by photodissociation. The large amount of HCN present in the inner wind provides effective line cooling that can dominate over that generated from CO line emission. It is also shown that great care needs to be taken in the radiative transfer modeling where nonlocal, and non-LTE, effects are important and where the radiation field from thermal dust grains plays a major role in exciting the HCN molecules. The amount of HCN present in the circumstellar envelope around IRC+10216 is consistent with predicted photospheric values based on equilibrium chemical models and indicates that any nonequilibrium chemistry occurring in the extended pulsating atmosphere has no drastic net effect on the fractional abundance of HCN molecules that enters the outer envelope. It further suggests that few HCN molecules are incorporated into dust grains.