Mycoflora and absence of aflatoxin contamination of commercialized cassava chips in Benin, West Africa

Studies conducted in Benin, in which the main staple foods are maize, cassava, groundnuts and yams, showed high levels of aflatoxin residues in blood of the exposed population. The natural contamination with fungi and aflatoxins in cassava chips sold at markets in Benin, West Africa was investigated. A total of sixty samples were sampled from open markets in 11 districts of 3 agroecological zones and analyzed for the presence of mycoflora and aflatoxin B₁, B₂, G₁ and G₂. Fourteen genera of fungi were associated with marketed dried cassava chips. Within these, twenty- two isolates were identified to species level, whereas four were identified only to genus. The dominating fungal species isolated were Rhizopus oryzae, Nigrospora oryzae, Chrysonilia sitophila, Cladosporium resinae, Cladosporium herbarum, Apergillus niger and Aspergillus flavus. Fifty-four out of sixty samples were contaminated with A. flavus. The rate of occurrence in CFU/g of A. flavus fungi was lower than for all other fungal species together. Aflatoxin was not detected in any of the samples analyzed using HPLC with post-column photochemical derivatization and fluorescence detection. The limit of detection (LOD) was 0.1 μg/kg. Results from this study suggest cassava chips are unlikely to be a source of aflatoxin in Benin, and that other staples such as maize and groundnuts are more important in aflatoxin exposure. Therefore it can be speculated that staples like maize and groundnut are more important in aflatoxin exposure.     

Enzyme studies during the production of agadagidi Part 1. Amylase activities

Amylase activities in fermenting agadagidi is reported. Highest amounts of reducing sugars produced by amylase activities in fermenting plantain chips, agadagidi samples and associated microorganisms were obtained at 30 and 35 °C. The best pH range for enzyme activity was 5.1–7.2.     

Single coil pair transcutaneous energy and data transceiver for low power bio-implant use

A transcutaneous energy and data transceiver built from low-cost offthe- shelf components, employing a single pair of planar air-cored coils fabricated on standard PCB substrates, is presented. The transceiver powers the receiver continuously via the parallel-tuned coil pair. The latter is then able to sample audio at 8000 bytes/s and send the bitstream to a digital-to-analogue convertor in the transmitter by amplitude modulating the transmitted power carrier signal.     

Studies in the process optimization and characterization of low formaldehyde emission urea‐formaldehyde resin by response surface methodology

Stringent control of formaldehyde emission standards the world over has intensified research and development effort to explore several paths for reducing formaldehyde release. A new generation of low odour resins is currently being developed and some resin manufacturers are now programming formaldehyde and urea additions at two or more stages in the overall reaction. This article reports on the studies conducted on a four‐stage condensation process consisting of the first stage involving a high acid environment followed by an alkaline condensation, a condensation under a pH 6, and finally neutralization to pH 7. A programmed variation consisting of changing “the number of additions” and “the duration between additions” of urea to formaldehyde was considered as an effective method to control the molecular weight, molecular weight distribution, and the oligomeric structures. Response surface methodology was employed to optimize the above conditions to produce particle boards with minimum formaldehyde emission and maximum internal bond strength. The studies showed that sequential addition of urea [“the duration between additions” and the “number of additions”] improved the internal bond strength and reduced formaldehyde emission of the particleboards. Detailed resin characterization in terms of the number and weight average molecular weights, molecular weight distribution, polydispersity, percentages of reactive moieties, and interlinking units present in the oligomer could be stipulated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2709–2719, 2007     

Dissolution of steelmaking slags in acetic acid for precipitated calcium carbonate production

A promising option for long-term storage of CO₂ is to fixate carbon dioxide as magnesium- and calcium carbonates. Slags from iron and steel works are potential raw materials for carbonation due to their high contents of calcium silicates. Precipitated calcium carbonate (PCC) is used as filler and coating materials in paper. If slag could be used instead of limestone for producing PCC, considerable energy savings and carbon dioxide emissions reductions could be achieved. In this paper, the leaching of calcium from iron and steel slags using acetic acid was investigated. Thermodynamic equilibrium calculations at atmospheric gas pressures showed that extraction of calcium is exothermic and feasible at temperatures lower than 156 °C, while the precipitation of calcium carbonate is endothermic and feasible at temperatures above 45 °C. The formation of calcium- and magnesium acetate in the solution was found to be thermodynamically possible. Laboratory-scale batch experiments showed that iron and steel slags rapidly dissolve in acetic acid in a few minutes and the exothermic nature of the reaction was verified. While silicon was successfully removed by filtration using solution temperatures of 70–80 °C, further separation methods are required for removing iron, aluminum and magnesium from the solution.     

Carbonation of calcium-containing mineral and industrial by-products

The use of carbon dioxide (CO₂) and calcium-containing by-products from industrial activities is receiving increasing interest as a route to valuable carbonate materials while reducing CO₂ emissions and saving natural resources. In this work, wet-chemical experimental data was assessed, which involved the carbonation of three types of materials in aqueous solutions, namely, 1) wollastonite, a calcium silicate mineral, 2) steelmaking slag, a by-product of steel production, and 3) paper bottom ash (PBA) from waste paper incineration. Aims were to achieve either a high carbonation degree and/or a pure carbonate product with potential commercial value. Producing a pure precipitated calcium carbonate (PCC) material that may find use in paper industry products puts strong requirements on purity and brightness. The parameters investigated were particle size, CO₂ pressure, temperature, solid/liquid ratio, and the use of additives that affect the solubilities of CO₂ and/or calcium carbonate. Temperatures and pressures were varied up to 180°C and 4 Mpa. Data obtained with the wollastinite mineral allowed for a comparison between natural resources and the industrial by-product materials, the latter typically being more reactive. With respect to temperature and pressure trends reported by others were largely confirmed, with temperatures above 150°C introducing thermodynamic limitations depending on CO₂ pressure. The influence of additives showed some promise, although costs may make recycling and reuse of additives a necessity for a large-scale process. When using steelmaking slag, magnetic separation may remove some iron-containing material from the process (although this is far from perfect), while the addition of bicarbonate supported the removal of phosphorous, aside from improving calcium extraction. The experiments with paper bottom ash (PBA) gave new data, showing that its reactivity resembles that of steelmaking slag, while its composition results in relatively pure carbonate product. Also, with PBA no additives were needed to achieve this.     

Derivatization of surface-bound peptides for mass spectrometric detection via threshold single photon ionization

Chemical derivatization of peptides allows efficient F2 laser single photon ionization (SPI) of Fmoc-derivatized peptides covalently bound to surfaces. Laser desorption photoionization mass spectrometry using 337-nm pulses for desorption and 157.6-nm pulses for threshold SPI forms large ions identified as common peptide fragments bound to either Fmoc or the surface linker. Electronic structure calculations indicate the Fmoc label is behaving as an ionization tag for the entire peptide, lowering the ionization potential of the complex below the 7.87-eV photon energy. This method should allow detection of many molecular species covalently or electrostatically bound to surfaces.     

Nutritional studies on agadagidi

The analysis showed a gradual fall of the sugar content as fermentation period increased. Ascorbic acid content decreased while nitrogen and crude protein increased during fermentation. The predominant amino acids are leucine, lysine, valine, asparagine and glutamic acid, methionine, phenylalanine.     

基于视频采集系统的肢体运动模型

为满足人体关节运动模型研究的需要,设计了一种基于机器视觉的肢体运动模式采集系统,系统由PCI-1411视频采集卡和LabVIEW数字图像处理平台构成。通过对采集到的肢体运动状态视频分帧进行处理,建立了肢体关节运动的相关数学模型,获得了较为准确的肢体运动参数。研究结果表明,采用视频采集技术建立的运动模型较传感器采集技术建立的模型有精确度高、处理速度快、系统误差小、数据易分析处理等优势。     

Improved Locomotor Recovery in a Rat Model of Spinal Cord Injury by BioLuminescent-OptoGenetic (BL-OG) Stimulation with an Enhanced Luminopsin

Irrespective of the many strategies focused on dealing with spinal cord injury (SCI), there is still no way to restore motor function efficiently or an adequate regenerative therapy. One promising method that could potentially prove highly beneficial for rehabilitation in patients is to re-engage specific neuronal populations of the spinal cord following SCI. Targeted activation may maintain and strengthen existing neuronal connections and/or facilitate the reorganization and development of new connections. BioLuminescent-OptoGenetics (BL-OG) presents an avenue to non-invasively and specifically stimulate neurons; genetically targeted neurons express luminopsins (LMOs), light-emitting luciferases tethered to light-sensitive channelrhodopsins that are activated by adding the luciferase substrate coelenterazine (CTZ). This approach employs ion channels for current conduction while activating the channels through treatment with the small molecule CTZ, thus allowing non-invasive stimulation of all targeted neurons. We previously showed the efficacy of this approach for improving locomotor recovery following severe spinal cord contusion injury in rats expressing the excitatory luminopsin 3 (LMO3) under control of a pan-neuronal and motor-neuron-specific promoter with CTZ applied through a lateral ventricle cannula. The goal of the present study was to test a new generation of LMOs based on opsins with higher light sensitivity which will allow for peripheral delivery of the CTZ. In this construct, the slow-burn Gaussia luciferase variant (sbGLuc) is fused to the opsin CheRiff, creating LMO3.2. Taking advantage of the high light sensitivity of this opsin, we stimulated transduced lumbar neurons after thoracic SCI by intraperitoneal application of CTZ, allowing for a less invasive treatment. The efficacy of this non-invasive BioLuminescent-OptoGenetic approach was confirmed by improved locomotor function. This study demonstrates that peripheral delivery of the luciferin CTZ can be used to activate LMOs expressed in spinal cord neurons that employ an opsin with increased light sensitivity.