Manufacture of Industrial Refractory Crucibles Based on Clays from Burkina Faso

In Burkina Faso, one of the three largest gold producers in West Africa, foundry activity is often paralyzed when basic equipment such as crucibles and cups are not available or should be imported. However, previous studies have shown the availability of kaolinite-rich clay resources that could be used for the local manufacture of silico-aluminous ceramic crucibles. This work allowed to manufacture industrial ceramic crucibles with local clays and then they were tested in foundry industry. The materials were manufactured from three (03) raw materials including two clays (SAB and ROU) and sand. The chemical and mineral analysis has shown that the raw materials are suitable for the formulation of refractory materials. The results of characterization of the materials formulated showed that the properties of use are appreciable. The porosity of the materials is relatively low (23 - 28 vol%) with a diametral compressive strength between 0.61 and 1.34 MPa. Crucibles sintered at 1250˚C with a stay of 2 hours have a mechanical strength capable of supporting the weight of the ores contained. These crucibles have a refractoriness under load (T0.5) above 1141˚C and resist chemical attacks. Tests were carried out in the industry at 1100˚C, and the results were satisfactory.

Investigation of Pollution Level of Traces Metals Elements in Agricultural Soil of Oubritenga Province of Burkina Faso

The purpose of this study was to investigate the pollution level of trace metals As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se and Zn in agricultural soil around the water reservoir. A total of 36 soil samples were collected both during off-season agriculture and pluvial agriculture from April to October 2022. The samples were analyzed for trace metals according to the standard methods of the US EPA 2007 with a microwave plasma atomic emission spectrometer (MP-AES), Agilent Model 4210. The pollution level was assessed using contamination factor (Cf) and modified contamination degree (mCd). During the off-season, the concentration of trace metals followed in descending order as Mn > Cr > Cu > Pb > Zn. As, Cd, Co, Hg, Ni, Sb and Se were below the detectable limits. In pluvial season, the concentration of traces of metal follows the order Mn > Cr > Zn > Cu > Ni > Pb > Hg > As. Cd, Co, Sb and Se remain below the detectable limits. The concentrations of Cr, Mn and Zn were lower in the off-season agriculture than in pluvial agriculture. For Cu and Pb, the concentrations were higher in the off-season than in pluvial agriculture. The Cf ranges from 0.24 to 11.70 depending on the considered trace metal. The Cf values of As, Ni, Pb, Zn and Mn indicated that the agricultural study soil was lowery contaminated by these trace metals. The agricultural study soil was moderately contaminated by Cr and Cu, and highly contaminated by Hg. Globally the agricultural study soil presents a moderate degree of contamination (mCd 2.25) by the eight trace metals studied. This result provides information on understanding the risks of trace metal contamination of agricultural soil. It is important to anticipate the control of soil contamination through regular monitoring of toxic metals in agricultural soils, control the quality of chemicals used in agriculture and regulate their use.

Synthesis, Crystal Structure and Biological Activity of(3S,8a R)-3-((1-Allyl-1H-3-indolyl)methyl)-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione

A derivative of Brevianamide F,(3 S,8 a R)-3-((1-allyl-1 H-3-indolyl)methyl)-hexahy-dropyrrolo[1,2-a]pyrazine-1,4-dione, was synthesized and characterized by 1 H NMR, 13 C NMR and confirmed by X-ray crystal structure analysis. This compound crystallizes in orthorhombic system, space group P212121 with a = 9.59590(10), b = 12.70430(10), c = 14.5425(2)A, V = 1772.86(3)A^3, Z = 4, μ(CuK α) = 0.712 mm^-1, Dc = 1.279 g/cm^3, 16019 reflections measured(9.24°≤2θ≤147.28°), 3524 unique(Rint = 0.0309, Rsigma = 0.0175) which were used in all calculations. The final R = 0.0567(I > 2σ(I)) and wR = 0.1411(all data). The structure exhibits intermolecular hydrogen bonds typed O–H…O, leading to the formation of one-dimensional chains. The title compound was tested for inhibitory activity toward B-16, C6, RM-1 and BV-2 cancer cell lines.

The Compatibility of Groups Used to Protect Phenolic Functionality during Oxone-Mediated Oxidative Esterification

Protecting groups often play an essential role in organic synthesis, particularly for multi-step synthesis or natural product total synthesis. Various protecting groups areavailable to mask the vulnerable functionality;phenolic hydroxy groups are noteworthy examples, but their stability differs when protected. Herein, the compatibility of protective phenolic functionality was investigated with the implementation of indium (III) triflate-catalyzed oxidative esterification using Oxone in methanol. A wide range of protective moieties was selected and subjected to Oxone-mediated oxidative esterification. For example, sulfonates were found to be sufficiently stable and inert whereas acetals were susceptible to reaction conditions. The details of this investigation are provided.

Optimization of Contents of Three Raw Clay Materials in Formulation of a Porcelain

Formulation of traditional hard porcelain generally requires 50% kaolin, 25% silica and 25% feldspar. Four porcelains formulation using the casting method, were prepared with different percentages of kaolinitic clay, sand and pegmatite referenced respectively NONG, SAB and PEG. The physico-chemical, mechanical and mineralogical characteristics were evaluated on specimens formulated and sintered at different temperatures from 1200˚C to 1300˚C. X-ray diffraction has revealed the presence of mullite and quartz as essentially crystalline phases. The specimen formulated with 55% NONG, 25% PEG and 20% SAB and sintered at 1240˚C gives better performance (water absorption: 0.17%, density: 2.42, open porosity: 0.42% and flexural strength: 53.54 MPa).

Evaluation of Combined Landscape Restoration Practices on Soil Organic Carbon Stocks in Semiarid Regions of Burkina Faso

Forest and landscape restoration (FLR) practices have been reported to improve soil organic carbon stocks (SOCs) and contributing to climate change mitigation. This study aims to evaluate the impact of combined FLR practices, mainly developed in semiarid regions, on SOCs. The SOCs, soil texture, bulk density (ρ), pH, CO2 emissions, and herbaceous biomass were determined at a 0 - 30 cm depth. The experimental design comprised degraded land without FLR practices and three sets of combined FLR practices. These practices included “zaï” + stone bunds + organic manure + assisted natural regeneration (ANR) used to convert degraded land into forest (GF) and cropland (PARL);“zaï” + stone bunds + crop rotation + crop/fallow successions + ANR used to convert degraded land into cropland (OARL) and “zaï”+ stone bunds + organic manure used to convert degraded land into cropland (KARL). SOCs were highest (20.02 t C ha−1) under OARL compared with the other combinations of FLR practices. SOCs increased by 99% (+0.2 t C ha−1⋅yr−1), 58% (+0.3 t C ha−1⋅yr−1) and 13% (+0.2 t C ha−1⋅yr−1) under GF, OARL and KARL, respectively, and decreased by 15% (−0.1 t C ha−1⋅yr−1) under PARL. This study provides additional information explaining SOC variation in restored degraded land through the implementation of a combination of FLR practices. This is useful for recommending the combination “zaï” + stone bunds + crop rotation + crop/fallow successions + ANR to improve SOCs in the semiarid agroecosystem.

Investigation into Protective Groups for Anilino Functionality upon Oxone-Mediated Oxidative Esterification

In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.

Electrochemiluminescence of metal-organic complex nanowires based on graphene-Nafion modified electrode for biosensing application

In this work, we chose tris(2,2′-bipyridyl)ruthenium(II)hexafluorophosphate(Ru(bpy)3(PF6)2), a metal-organic complex material,to prepare nanowires, which were subsequently applied for the construction of electrochemiluminescence(ECL) biosensor by immobilizing them onto a glassy carbon electrode(GCE) with graphene-Nafion composite films. The graphene therein, being a two-dimensional carbon nanomaterial with outstanding electronic properties, can obviously improve the conductivity of the Nafion film, as well as enhance the electrochemical signal and ECL intensity of the Ru(bpy)3(PF6)2 nanowires(RuNWs) at low graphene concentration. The developed biosensor exhibited excellent ECL stability with tripropylamine(TPrA) as co-reactant. The ECL biosensor exhibited high sensitive ECL response in a wide linear range and low detection limit for the detection of proline. It is considered that the oxidation products of proline would be responsible for the ECL enhancement. The large electro-active area of the nanowires and the enhancement effect of the graphene played critical roles in the high detection performance of the ECL biosensor. The results demonstrated herein may provide a useful enlightenment for the design of more sensitive ECL biosensors.

Design, Synthesis and Antitumor Activity of Novel Indolin-2-one Derivatives Containing 4-Thiazolidinone Moiety

A series of novel indolin-2-one derivatives containing 4-thiazolidinone moiety（7a--7r） were synthesized and evaluated for their in vitro antitumour activities against MDA-MB-231 （human breast cancer）, H460（human lung cancer） and HT-29（human colon cancer） cell lines by standard 3-（4,5-dimethylthiazae-2-yl）-2,5-diphenyltetrazo- lium bromide（MTT） assay. Representative compounds（Td, 7k, 7m, 7p） with higher cytotoxicity were further examined against one normal cell line（WI-38, human fetal lung fibroblasts）. The preliminary investigation shows that most of the compounds display moderate to excellent potency and high selectivity against different human cancer cell lines. In particular, the most potent compound 7m shows promising cytotoxicity against MDA-MB-231, H460 and HT-29 cell lines with IC5o values of 0.78, 0.056 and 0.018 μmol/L, respectively. The potency is much higher than that of Sunitinib（IC50=3.46 μmol/L against MDA-MB-231, IC50=2.59 μmol/L against H460, IC50=1.50 μmol/L against HT-29） by 4.4, 46.3 and 83.3 fold.

Targeted mutagenesis in Arabidopsis thaliana using CRISPR-Casi2b/C2ci^°°

Casi2b/C2ci is a newly identified class 2 CRISPR endonuclease that was recently engineered for targeted genome editing in mammals and rice.To explore the potential applications of the CRISPR-Casi2b system in the dicot Arabidopsis thaliana,we selected BvCasi2b and BhCasi2b v4 for analysis.We successfully used both endonucleases to induce mutations,perform multiplex genome editing,and create large deletions at multiple loci.No significant mutations were detected at potential off-target sites.Analysis of the insertion/deletion frequencies and patterns of mutants generated via targeted gene mutagenesis highlighted the potential utility of CRISPRCasi2b systems for genome editing in Arabidopsis.