Modeling and analysis of the removal of an organic pollutant from a water body using fungi

In this paper, a non linear mathematical model for removing an organic pollutant such as a dye from a water body is proposed and analyzed. In the modeling process four variables are considered, namely, (i) the concentration of the dye, (ii) the density of fungus population, (iii) the concentration of a nutrient and (iv) the concentration of dissolved oxygen (DO). It is assumed that an organic pollutant is present in water with given concentration or discharged with a constant rate in water. It is assumed further that fungus population is kept alive and active due to supply of a nutrient. It is considered that nutrient and oxygen are supplied to the water body from outside with constant rates. The model is analyzed by using the stability theory of differential equations. The model analysis shows that organic pollutant can be removed from the water body by fungus population and the level of degradation depends upon the concentration of organic pollutant, the density of fungal population and the interaction processes involved.The simulation analysis of the proposed model confirms the analytical results. It is also found that these results are qualitatively in line with the experimental observations of one of the authors (Sanghi).     

Quality assessment of Cortex Phellodendri by high‐performance liquid chromatography coupled with electrospray ionization mass spectrometry

A simple method based on liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (LC‐DAD‐ESI‐MS) was developed for the quality assessment of Cortex Phellodendri (CP), which was mainly derived from two species of Phellodendron chinense Schneid and Phellodendron amurense Rupr. Total 41 compounds, including 14 phenols, 24 alkaloids and three liminoidal triterpenes were identified or tentatively characterized from the 75% methanol extract of CP samples by online ESI‐MSⁿ fragmentation and UV spectra analysis. Among them, two phenols and six alkaloids were simultaneously quantified using HPLC‐DAD method. The validated HPLC‐DAD method showed a good linearity, precision, repeatability and accuracy for the quantification of eight marker compounds. Furthermore, the plausible fragmentation pathway of the representative compounds were proposed in the present study. The differences of the chemical constituents content and the comprehensive HPLC profiles between the two CP species using LC‐DAD‐ESI‐MS method are reported for the first time, indicating that the CP drugs from different resources should be used separately in the clinic. Copyright © 2009 John Wiley & Sons, Ltd.     

Understanding the interaction of multi-walled carbon nanotubes with mutagenic organic pollutants using computational modeling and biological experiments

Carbon nanotubes (CNTs) are very promising materials to remove pollutants from the environment. To develop safe, efficient technologies, it is necessary to understand the mechanisms of interaction between CNTs and pollutants. This requires innovative, interdisciplinary approaches. Detailed chemical analysis of the CNTs along with computational modeling can provide important information about the mechanisms of interaction. If biological experiments are included in these studies, useful complementary information is obtained. To exemplify the use of this approach, we present a case study in which detailed calculations and the Salmonella mutagenicity assay were applied to elucidate how multi-walled CNTs interact with 1-nitropyrene, an important mutagenic pollutant.     

Priority rule-based heuristic for multi-mode resource-constrained project scheduling problems with resource vacations and activity splitting

This paper presents a priority rule-based heuristic for the multi-mode resource-constrained project scheduling problem with the splitting of activities around unavailable resources allowed. All resources considered are renewable and each resource unit may not be available at all times due to resource vacations, which are known in advance. A new concept called moving resource strength is developed to help identify project situations where activity splitting is likely to be beneficial during scheduling. The moving resource strength concept is implemented in priority rule-based heuristics to control activity splitting when scheduling. Multiple comparisons of the performance of combination of activity–mode priority rules used in the heuristics are provided. Computational experiments demonstrate the effectiveness of the heuristic in reducing project makespan, and minimizing activity splitting.     

A chi-square method for obtaining a priority vector from multiplicative and fuzzy preference relations

Decision makers (DMs)’ preferences on decision alternatives are often characterized by multiplicative or fuzzy preference relations. This paper proposes a chi-square method (CSM) for obtaining a priority vector from multiplicative and fuzzy preference relations. The proposed CSM can be used to obtain a priority vector from either a multiplicative preference relation (i.e. a pairwise comparison matrix) or a fuzzy preference relation or a group of multiplicative preference relations or a group of fuzzy preference relations or their mixtures. Theorems and algorithm about the CSM are developed. Three numerical examples are examined to illustrate the applications of the CSM and its advantages.     

Photocyclization of 2-azido-1-(4-<Emphasis Type="Italic">tert</Emphasis>-butylphenoxy)-9,10-anthraquinone in the presence of substituted phenols

New types of phototransformations in the quinone series, viz., photocyclizations of 1-aryloxy-2-azido-9,10-anthraquinone in the presence of phenols, were studied. The photolysis affords mainly 5H-naphtho[2,3-c]phenoxazine-8,13-diones, in which the nitrogen atom is covalently bound to the phenyl ring of the attached phenol. As a result, complex polycyclic derivatives of phenoxazines were prepared in high yields in one step. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1089–1093, June, 2007.     

三角模糊数互补判断矩阵的一种排序方法

给出三角模糊数互补判断矩阵的概念及三角模糊数相互比较的可能度公式 ,提出一种基于可能度的三角模糊数互补判断矩阵排序方法 ,通过算例说明该方法的可行性和有效性。     

有机物在水/双阳离子有机膨润土界面的吸附贡献率研究

在长、短碳链表面活性剂总量恒定条件下制备了一系列双阳离子有机膨润土，研究了其对水中苯胺，对硝基苯酚2，4－二氯酚的吸附行为，结果表明双阳离子有机膨润土对有机物的分配系数（Kd）与有机碳含量（f∝)、辛醇－水分配系数（lgKow)成线性正相关，与溶解度（lgS)成线性负相关，通过数学模拟，首次描述了表面吸附和分配作用两种吸附机制的相对贡献率和改性表面活性剂配比的关系；结果表明双阳离子有机膨润土对水中有机物两种吸附机制的主导地位与有机物本身性质有关，其主导作用发生变化的拐点与长碳链表面活性剂所占比重相关。     

Recent Advances in Common Transition Metal-Based Single-Atom Nanozymes and Their Applications in Pollutant Detection and Degradation

Nanozymes can be used as favorable substitutes for natural enzymes because of their strong catalytic activity and good stability. At the same time, research on single-atom catalysts (SACs) with isolated metal atoms as active centers is also in full swing, showing excellent performance in a variety of catalytic reactions. With the in-depth study of SACs, people have a comprehensive understanding of them and put forward the concept of single-atom nanozymes (SAzymes) by combining nanozymes with SACs. As a new type of nanomaterial, SAzymes have attracted great interest due to their remarkable catalytic activity and rapid energy conversion. However, most applications of SAzymes are mainly in the fields of biomedicine and biosensing, and less research has been done in the field of the environment. Based on the amazing ability of nanozymes to detect and degrade pollutants, SAzymes are also used in the environmental field, and even they will show better capabilities. This review mainly analyses common transition metal-based SAzymes and describes their applications in the field of environmental pollutants.