A novel fluorescent probe based on rhodamine hydrazone derivatives bearing a thiophene group for Al3+

In the present work, a novel 5‐methyl‐thiophene‐carbaldehyde‐functionalized rhodamine 6G Schiff base (RA) was designed and easily prepared as an Al³⁺ fluorescent and colorimetric probe, which could selectively and sensitively detect Al³⁺ by showing enhanced fluorescence emission. Meanwhile distinct color variation from colorless to pink also provided ‘naked eye’ detection of Al³⁺, due to the ring spirolactam opening of the rhodamine derivative. Other metal ions (including K⁺, Mg²⁺, Na⁺, Ba²⁺, Mn²⁺, Cd²⁺, Fe²⁺, Ni²⁺, Pb²⁺, Zn²⁺, Hg²⁺, Co²⁺, Li⁺, Sr²⁺ and Cu²⁺) could only induce limited interference. The detection limit of the fluorescent probe was estimated to be 4.17 × 10^?6 M, the binding constant of the RA–Al³⁺ complex was 1.4 × 10⁶ M^?1. Moreover, this fluorescent probe RA possessed high reversibility. As aluminum is a ubiquitous metal in nature and plays vital roles in many biological processes, this chemosensor could be explored for biological study applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Memory Deficit in Mice Administered Aluminum–maltolate Complex

Recently, aluminum (Al) has been identified as one of the environmental factors responsible for cause certain nerve degeneration diseases, particularly, Alzheimer’s disease (AD). However, the relationship between Al and AD is controversial. We previously examined whether Al induced neurotoxin in the brain of mice when aluminum–maltolate complex (ALM) was administered daily for 120 days. Our results revealed that Al accumulated in the brain induced oxidative stress, and the nerve degeneration was detected in the brain of the ALM-treated group. On the basis of these results, we have tried to examine whether the incorporated Al affects memory in mice with regard to an indicator of spatial memory deficits depending on the chemical forms of Al, namely, as an ion (AlCl₃) and in the form of a complex (ALM). We administered saline, AlCl₃, and ALM at a concentration of 40 μmol Al/kg body weight to mice by daily ip injections for 60 days. We assessed spatial memory by a water maze task and determined the Al levels in the brain of the mice by the neutron activation analysis method. Spatial memory deficit as an indicator of the swimming time was related to Al accumulation in the brain of mice; the chemical form of the Al compound was important in order to exhibit the memory deficit in mice; the uptake of Al is higher in mice when it is administered in a complex form than in an ionic form.     

The Physiology, Genetics and Molecular Biology of Plant Aluminum Resistance and Toxicity

Aluminum (Al) toxicity is the primary factor limiting crop production on acidic soils (pH values of 5 or below), and because 50% of the world’s potentially arable lands are acidic, Al toxicity is a very important limitation to worldwide crop production. This review examines our current understanding of mechanisms of Al toxicity, as well as the physiological, genetic and molecular basis for Al resistance. Al resistance can be achieved by mechanisms that facilitate Al exclusion from the root apex (Al exclusion) and/or by mechanisms that confer the ability of plants to tolerate Al in the plant symplasm (Al tolerance). Compelling evidence has been presented in the literature for a resistance mechanism based on exclusion of Al due to Al-activated carboxylate release from the growing root tip. More recently, researchers have provided support for an additional Al-resistance mechanism involving internal detoxification of Al with carboxylate ligands (deprotonated organic acids) and the sequestration of the Al-carboxylate complexes in the vacuole. This is a field that is entering a phase of new discovery, as researchers are on the verge of identifying some of the genes that contribute to Al resistance in plants. The identification and characterization of Al resistance genes will not only greatly advance our understanding of Al-resistance mechanisms, but more importantly, will be the source of new molecular resources that researchers will use to develop improved crops better suited for cultivation on acid soils.     

Effect of Enhanced Calcium Supply on Aluminum Toxicity in Relation to Cell Wall Properties in the Root Apex of Two Wheat Cultivars Differing in Aluminum Resistance

The present study was conducted to investigate the effects of enhanced Ca supply on Al toxicity in relation to cell wall properties in two wheat (Triticum aestivum L.) cultivars differing in Al resistance. Seedlings of Al-tolerant Inia66 and Al-sensitive Kalyansona cultivars were grown in complete nutrient solutions for 4 days then subjected to treatment solutions containing Al (0, 50 μM) and Ca (500, 2500 μM) at pH 4.5 for 24 h. Root elongation was affected greatly by Al treatment in the Al-sensitive cultivar and a significant improvement in root growth was observed with enhanced Ca supply during Al stress. Pectin and hemicellulose contents in the root cell walls increased with Al stress, and this increase was more conspicuous in the Al-sensitive cultivar. The molecular mass of hemicellulosic polysaccharides increased with Al treatment in the Al-sensitive cultivar and decreased with enhanced Ca supply. The increase in the molecular mass of hemicellulosic polysaccharides was attributed to increased content of glucose, arabinose and xylose in neutral sugars. Enhanced Ca supply slightly decreased the content of these components with Al stress. Aluminum treatment increased the contents of ferulic and p-coumaric acid, especially in the Al-sensitive cultivar, by increasing peroxidase (POD, EC 1.11.1.7) and phenylalanine ammonia lyase (PAL, EC 4.3.1.5) activity, whereas enhanced Ca supply during Al stress decreased the content of these components by decreasing POD and PAL activity. These results suggest that the increased molecular mass of hemicellulosic polysaccharides and phenolic compounds in the Al-sensitive cultivar with Al stress might have inhibited root elongation associated with cell wall stiffening related to cross-linking among cell-wall polymers and lignin. Enhanced Ca supply might maintain the normal synthesis of these materials even with Al stress.     

小麦根系对铝毒的反应及其与根细胞壁组分和细胞壁对铝的吸附-解吸性能的关系

研究了小麦根系对铝毒的反应与不同根段细胞壁的组分及细胞壁对铝的吸附解吸性能的关系。结果表明,30μmol/LAlCl3可迅速抑制根系伸长,在铝处理30h时其根长仅为对照的30.2%;小麦根系相对伸长率随着铝浓度的提高而急剧降低,30μmol/LAlCl3处理24h对根系伸长的抑制率高达70.9%。小麦根系中距根尖0~10mm根段的铝含量和细胞壁中果胶糖醛酸含量明显高于距根尖10~20mm根段;距根尖0~10mm根段细胞壁对铝的吸附量明显大于距根尖10~20mm根段,而前者吸附态铝的解吸率低于后者;铝浓度从10μmol/L提高到20μmol/L时细胞壁对铝的吸附量增加,但对铝的解吸没有明显影响。采用1.0mol/LNH3·H2O对细胞壁预处理2h降低果胶甲基酯化程度后,铝吸附量降低了20.9%,但对铝解吸率没有影响。由此可见,小麦根尖是铝毒的主要位点,细胞壁果胶含量和果胶甲基酯化程度对小麦不同根段细胞壁对铝的吸附、积累具有重要作用,铝与细胞壁的结合是根系对铝毒胁迫反应的重要原因。     

An assessment of alternative diesel fuels: microbiological contamination and corrosion under storage conditions

Experiments were designed to evaluate the nature and extent of microbial contamination and the potential for microbiologically influenced corrosion of alloys exposed in a conventional high sulfur diesel (L100) and alternative fuels, including 100% biodiesel (B100), ultra-low sulfur diesel (ULSD) and blends of ULSD and B100 (B5 and B20). In experiments with additions of distilled water, all fuels supported biofilm formation. Changes in the water pH did not correlate with observations related to corrosion. In all exposures, aluminum 5052 was susceptible to pitting while stainless steel 304L exhibited passive behavior. Carbon steel exhibited uniform corrosion in ULSD and L100, and passive behavior in B5, B20, and B100.     

Cu/PAA的制备及其抗菌性能研究

采用两步阳极氧化法制备出孔径为75nm的多孔阳极氧化铝(PAA75),并使用交流电沉积技术在PAA75孔道内装载纳米Cu。采用场发射扫描电镜(FESEM)观察样品微观形貌,进一步采用X射线衍射(XRD)、X射线光电子能谱分析(XPS)对材料化学组成及晶型进行了表征和分析。选用大肠杆菌(E.coli ATCC 8099)和金黄色葡萄球菌(S.aureus ATCC6538)测试Cu/PAA的抗菌性能。研究结果表明,本方法制备的Cu/PAA中Cu主要以Cu0存在,并且Al和Cu所占原子比为17.77∶0.71。体外抗菌测试表明,Cu(10s)/PAA对E.coli的1d、2d和3d抑菌率分别为82%±11%、78%±7%和45%±4%,对S.aureus的1d、2d和3d抑菌率分别为89%±4%、75%±8%和56%±11%。     

Aluminum: a pH-dependent inhibitor of NADP-isocitrate dehydrogenase from porcine heart

Aluminum showed a pH-dependent inhibitory effect on NADP-isocitrate dehydrogenase from porcine heart. Aluminum ions (Al³⁺) acted as a partial competitive inhibitor of the enzyme with respect to the substratethreo-Ds-isocitrate and inhibited the enzyme non-competitively with respect to NADP at pH 6.85. Fractional velocity plot analysis showed theK _i of the enzyme for aluminum ions to be 0.88m. When pH was elevated to 8.0, aluminum ions, which occur as a form of the Al(OH)₄ ^– anion, acted as partial uncompetitive and non-competitive inhibitors of the enzyme with respect to the substrates isocitrate and NADP, respectively. TheK _i of the enzyme was determined to be 5.64 m at pH 8.0 by fractional velocity plot analysis. The inhibition of NADP-isocitrate dehydrogenase by two forms of aluminum ions may explain aluminum toxicity in various tissues and organs.     

Evaluation of the electro-ultrafiltration technique (EUF) as a measure of the K supplying power of Quebec soils

The electro-ultrafiltration (EUF) method has been used to evaluate the short-term and long-term supplying power of soils for many essential plant nutrients. The objective of this study was to compare the capacity of EUF with other extraction techniques to predict the plant availability of soil K and K fertilizer responsiveness by 10 cuts of alfalfa (Medicago sativa L.) growing over a 366-day period. Increasingly higher average concentrations of soil K were extracted by EUF at 50 V and 20°C (29 mg kg^-1), EUF at 200 V and 20°C (48 mg kg^-1), 0.002 M SrCl₂ (55 mg kg^-1), EUF at 200 V and 80°C (85 mg kg^-1), 0.1 M HCl (105 mg kg^-1), Mehlich 3 (119 mg kg^-1), 1 M NH₄OAc (120 mg kg^-1) and boiling 1 M HNO₃ (601 mg kg^-1). The large content of vermiculitic minerals in the silt and clay fractions is responsible for EUF desorbing more K in 55 minutes than NH₄OAc in 29 out of 30 soils. The total amount of K desorbed by EUF at 80°C was as effective as Mehlich 3-extractable K in predicting K uptake for the first three cuts and was best among the extracting procedures after boiling 1 M HNO₃ in predicting the long-term K supply, the uptake of K from non-exchangeable sources and the relative yield of alfalfa over 10 cuts. The desorption of soil K with EUF provides a better evaluation of the K-supplying power of Quebec soils than the extractants currently used, especially on a long-term basis.Contribution no. 396.