Determination of mimosine by a sensitive indirect spectrophotometric method

A simple and sensitive indirect spectrophotometric method is described for the determination of mimosine based on its reaction with diazotized sulfanilamide (DZSAM). DZSAM couples with N-(1-naphthyl)ethylenediamine (NEDA) forming a pink colored azodye, absorbing maximally at 540 nm (ε_max=27 mM⁻¹ cm⁻¹). In the present method, mimosine was first reacted with known excess of DZSAM and the unreacted DZSAM was determined by coupling with NEDA. The reaction of mimosine with DZSAM proceeded optimally at neutral pH. The decrease in absorbance of the DZSAM-NEDA-coupled product obeyed Beer’s law in the concentration range of 0.005-0.15 μg ml⁻¹ of mimosine. The present method was applied to estimate mimosine in plant extracts containing lesser than 0.05 μg ml⁻¹ with recovery at 99±0.41%. The method described is superior to other reported methods in terms of ease of adaptability and sensitivity.     

Innovative stabilization/solidification processes of fly ash from an incinerator plant of urban solid waste

Fly ash samples from an incineration plant of urban solid waste (USW) were submitted to a stabilization/solidification process based on encapsulation with a polyester resin. With this process, a very limited increase of about 25% in weight and a compressive strength as high as 1200 kg/cm² can be obtained. The efficiency of the process to stabilize/solidify the residues and to reduce the pollutant release was evaluated by performing both mechanical and leaching tests following the IRSA–CNR standard method. The leaching test was based on treating the sample with an acetic acid solution adjusted to pH 5.2 for 24 h under magnetic stirring. Toxic metals (Pb, Cd, and Cu) and organic pollutants (PAHs, PCBs, and OCPs) were determined in raw fly ash samples and in the leaching solutions of treated samples. Raw residues showed higher concentrations of trace metals than the regulatory limits, whereas the stabilized/solidified residues showed a concentration of all the pollutants lower than the regulatory limits and a compressive strength much higher than the suggested minimum value. Finally, a critical comparison with conventional stabilization/solidification processes based on the use of Portland cement highlighted that the polyester resin-based process performed much better in terms of the release of both organic and inorganic pollutants, thus substantially lowering the environmental impact of these residues.     

Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties

Toxic metal (Cd²⁺, Hg²⁺, Pb²⁺, and Ag⁺) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN₄, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ⁴N^1,4,7,10)(NO₃)₂)] (1), [Hg([12]ane-κ⁴N^1,4,7,10)(NO₃-κ²O,O`)]NO₃ (2), [Pb₂([12]ane-κ⁴N^1,4,7,10)₂][Pb(NO₃)₆] (3) and one polymeric structure {[Ag₂([12]ane-κ³N^1,4,7)(μ₂-[12]aneN¹⁰)](NO₃)₂?2H₂O)}_n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s² lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd²⁺ and Pb²⁺ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by ¹H NMR. Both methods confirm similar cyclen complexing properties toward Zn²⁺ biometal and Cd²⁺, Pb²⁺ toxic metals.     

Synthesis and characterization of novel optically active poly(amide-imide)s and poly(ester-imide)s containing calix[4]arene and amino acid units with binding ability towards alkali metal and toxic heavy metal cations

<正>A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene.The optically active monomers were synthesized by dehydration of L-leucine(and L-isoleucine) and 3,3',4,4'-benzophenonetetracarboxylic- 3,3',4,4'-dianhydride(3) followed by reaction with thionyl chloride to form 5a and 5b.Two methods,polymerization under microwave irradiation and solution polymerization in CH_2Cl_2/TEA,were then employed to carry out the condensation polymerization of 2 with the optically active monomers 5a and 5b,respectively.The polymerization conditions affected the kind of resulting polymers,poly(amide-imide)s(PAIs) 6a and 6b and poly(ester-imide)s(PEIs) 6a' and 6b' were obtained selectively in good yields and moderate inherent viscosities.Sorption-extraction experiments were carried out using cram picrate extraction method and verified good binding ability of the resulting calixarene-based polymers towards silver,alkali metal and toxic heavy metal cations.Also thermogravimetric analysis indicated that the resulting PAIs and PEIs were thermally stable.     

Sorption of Arsenic Oxyanions from Aqueous Solution on Goethite: a Study of Process Modelling

In the course of researching methods of sampling and monitoring toxic metals (as arsenic ions) in water and wastewaters, we selected the use of sorption for in-depth examination. Among other things, sorption modelling was investigated by the mechanism of surface complexation in order to describe the process or even predict the outcome for the expected rate, and in general, to develop this detection technique for pollutants. This investigation will include the application of goethite mineral as the suitable metal ion sorbent and the use of appropriate computer software. The relative thermodynamic aqueous speciation of the solution, in similar experimental conditions, was also studied.     

凤凰木种子毒蛋白的高效凝胶过滤色谱分析

介绍用ＨＰＧＦＣ（高效凝胶过滤色谱）对凤凰木种子中提取的３种毒蛋白分别进行色谱分析。并对分离的蛋白峰进行紫外光谱扫描来确认蛋白的纯度。根椐标准相对分子质量曲线,分别得到它们的相对分子质量并与ＳＤＳ－ＰＡＧＦ（十二烷基磺酸钠－聚丙烯酰胺凝胶电泳）所得结果进行比较,用柱后衍生法测定了３个蛋白各自的氨基酸组成。     

Biotransformation,multifunctional recycling mechanism of nanostructures,and evaluation of the safety of nanoscale materials

Current evidence of concept analyses recommending nanotechnology for biomedical uses abounds in recent research. The area of biotechnology interfaces with nanostructures, reconfigures their composition, and alters their characteristics; which influences the dispersion of the particles, the biotransformation they cause, and their potential toxic effect. It is vital to link the idea of the lifecycle of nanostructures to the biological impacts and use methodologies to identify, estimate, and track the gradual bioprocessing of nanostructures in vivo, from a body-wide level to a nanoscopic size. This is necessary because understanding how nanostructures processing, degradation, persistence, and recycling predict potential exposure risks. The safe implementation of nanotechnology-based products in biomedical applications necessitates an extensive understanding of the recycling and transformations of nanomaterials in a living organism. Long-term fate in the body is crucial, as it governs potential environmental risks to human health. Strategies may be used to manage the long-term outcome of nanostructures in an organism since, in addition to composition, their design also affects how long they last and how easily they degrade. The lifespan of nanoparticles, a flexible and biocompatible category of nanostructures that have made it into clinical trials, is the subject of this article. Strategies may be used to manage the long-term outcome of nanoparticles in an organism since, in addition to composition, their design also affects how long they last and how easily they degrade. This review explained the safety of nanoscale materials, biotransformation, and the multifunctional recycling mechanism of nanostructures.     

A Comparative Toxicity Study of TiO2 Nanoparticles in Suspension and Adherent Culture Under the Dark Condition

The present study focused on the different acute toxicity of TiO₂ nanoparticles(TiO₂ NPs) towards the bacteria in suspension culture and adherent culture under the dark conditions. The study investigated the bacteria toxicity with TiO₂ NPs at different concentrations(1—2000 mg/L), sizes(10 nm, 35 nm) and specific surface areas in unit volume solution(0—224 m²/L) characterized by the cell viability, extracellular polymeric substances(EPS) release and biofilm formation. The bacteria in adherent culture was found to be more resistant against the toxicity of TiO₂ NPs compared to that in suspension culture. An NP dose and surface area dependent(rather than the size) bacterial viability was observed in suspension culture, specifically the surface area positively correlated with the toxicity of TiO₂ NPs. The size of TiO₂ NPs, however, played a more critical role in toxicity of TiO₂ NPs in adherent culture. Therefore, the surface area dependent toxicity of TiO₂ NPs is a comprehensive parameter describing the dose and size dependent toxicity of TiO₂ NPs. The electron microscopic(SEM, TEM, EDX) observations suggested the EPS release and biofilm formation, during aggregation of TiO₂ NPs on the bacteria after 12 h cultivation in adherent culture under the dark condition. A possible toxic mechanism could be that “effective surface areas” that directly contact with the bacterial membrane greatly contributed to the toxicity of TiO₂ NPs in both suspension culture and adherent culture. Therefore, as for the possible resistance mechanism, EPS secretion and subsequent biofilm formation may protect the bacteria against the toxicity of TiO₂ NPs.     

An XPS analytical approach for elucidating the microbially mediated enargite oxidative dissolution

In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu₃AsS₄) was studied on powdered samples exposed to 9K nutrient solution (pH 2.3) inoculated by Acidithiobacillus ferrooxidans initially adapted to arsenopyrite. These conditions simulate the acid mine environment. The redox potential of the inoculated solutions increased up to +0.72 V vs normal hydrogen electrode (NHE), indicating the increase of the Fe³⁺ to Fe²⁺ ratio, and correspondingly the pH decreased to values as low as 1.9. In the sterile 9K control, the redox potential and pH remained constant at +0.52 V NHE and 2.34, respectively. Solution analyses showed that in inoculated medium Cu and As dissolved stoichiometrically with a dissolution rate of about three to five times higher compared to the sterile control. For the first time, X-ray photoelectron spectroscopy (XPS) was carried out on the bioleached enargite powder with the aim of clarifying the role of the microorganisms in the dissolution process. XPS results provide evidence of the formation of a thin oxidized layer on the mineral surface. Nitrogen was also detected on the bioleached surfaces and was attributed to the presence of an extracellular polymer substance layer supporting a mechanism of bacteria attachment via the formation of a biofilm a few nanometers thick, commonly known as nanobiofilm. Figure SEM image of enargite is in the background of the figure; in foreground the scheme of the dissolution mechanism in presence of microorganisms showing a sulphur enriched layer; the mechanism is supported by the presence of the high binding energy signal in the S2p photoelectron spectrum (upper-right).     

Quality Assessment of Honey Using Modern Analytical Tools

The quality of eighteen honey samples collected from the Western district of Saudi Arabia was assessed according to the International Honey regulatory standards using modern analytical methods. A number of quality criteria were measured to determine the botanical and geographical origin of honey. Hydroxymethylfurfural (HMF) as an adulteration marker was analyzed and detected quantitatively via high performance liquid chromatography (HPLC). The moisture content was assessed by Karl Fisher coulometric method using an automatic potentiometric titrator. While, mineral content and toxic heavy metal ions were determined using an inductively coupled plasma-atomic emission spectrometry (ICP-AES) technique after microwave digestion. All the investigated honey samples were of good quality. The elements with the highest frequency were K, Se, and Cd. High content of Cd and Se were found in samples (7 and 9). The maximum residues limit of the most dangerous metal for the human health lead was below European Standards.