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1

Effects of hole perpendicularity error on load distribution in single-lap double-bolt composite joints

Li R., Xiao R., Ge E., Gao H., Bao Y., Liu X.

Engineering Transactions

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2018

|

Vol. 66, iss. 1

3--19

EN

Although automated machines are widely used in composite structure manufacturing, manually drilled holes are usually necessary due to spatial constrains and holes with perpendicularity errors are occasionally generated as a result. Considering the anisotropic properties of composite material, the influences of hole perpendicularity error on mechanical performances of composite joints are different from those of isotropic material. In this study, the effects of hole perpendicularity error on load distribution in single-lap double-bolt composite joints are discussed. A finite element model is first developed and verified both by analytical and experimental results. Parametric studies are then carried out taking into consideration bolt torque and hole perpendicularity error, represented by hole tilting direction and tilting angle. It is found that the hole tilting direction significantly affects on load distribution in composite joints. Although the loads taken by bolts are not significantly affected, it may make one composite plate take more than 60% of total loads. In addition, the influences of tilting angle on load distribution can be ignored in most cases, and as for the bolt torque, it is to enhance the influence of hole tilting direction.

2

Linear genetic programming control for strongly nonlinear dynamics with frequency crosstalk

Li R., Noack B., Cordier L., Borée J., Kaiser E., Harambat F.

Archives of Mechanics

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2018

|

Vol. 70, nr 6

505--534

EN

We advance Genetic Programming Control (GPC) for turbulence flow control application building on the pioneering work of [1]. GPC is a recently proposed model-free control framework which explores and exploits strongly nonlinear dynamics in an unsupervised manner. The assumed plant has multiple actuators and sensors and its performance is measured by a cost function. The control problem is to find a control logic which optimizes the given cost function. The corresponding regression problem for the control law is solved by employing linear genetic programming as an easy and simple regression solver in a high-dimensional control search space. This search space comprises open-loop actuation, sensor-based feedback and combinations thereof — thus generalizing former GPC studies [2, 3]. This new methodology is denoted as linear genetic programming control (LGPC). The focus of this study is the frequency crosstalk between unforced, unstable oscillation and the actuation at different frequencies. LGPC is first applied to the stabilization of a forced nonlinearly coupled three-oscillator model comprising open- and closed-loop frequency crosstalk mechanisms. LGPC performance is then demonstrated in a turbulence control experiment, achieving 22% drag reduction for a simplified car model. In both cases, LGPC identifies the best nonlinear control achieving the optimal performance by exploiting frequency crosstalk. Our control strategy is suited to complex control problems with multiple actuators and sensors featuring nonlinear actuation dynamics. Significant further performance enhancement is envisioned in the more general field of machine learning control [4].

3

Compressive optical image encryption using phase-shifting interferometry on a joint transform correlator

Li J., Jia B., Dai X., Lei M., Yang C., Li J., Li H., Li R.

Optica Applicata

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2017

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Vol. 47, nr 2

245--256

EN

A compressive optical image encryption method, which combines compressive sensing with phase-shifting interferometry on a joint transform correlator, is proposed in the fully optical domain. The object image is first permutated using a binary scrambling method. Next, the permutated object field is encrypted and registered as the holograms by phase-shifting interferometry on the joint transform correlator setup. Then, the encrypted images and the key are compressed to the compressed data using single-pixel compressive imaging. The original image can be reconstructed and decrypted using the specified algorithm. The simulations demonstrate that the method is effective and suitable for image security transmission.

4

Removal of uranium(VI) from aqueous solution by rice husk

Xia L., Li R., Xiao Y., Zheng W., Tan K.

Environment Protection Engineering

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2017

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Vol. 43, nr 4

41--53

EN

Basic aspects of uranium adsorption by rice husk have been investigated. The influences of various experimental parameters such as pH, time, adsorbent dosage, rice husk size, temperature and various concentrations of uranium on uptake were evaluated. The thermodynamics and kinetics of adsorption were analyzed by FT-IR and SEM. The adsorption capacity for uranium on rice husk increased upon increasing initial concentration of uranium and temperature, while decreased with the increase of the amount of rice husk. Maximum uranium adsorption was observed at pH = 3 and particle size between 120 μm and 150 μm. Adsorption equilibrium was achieved within 60 min. At 25 °C, the saturated adsorption capacity qmax was up to 15.14 mg/g when the initial concentration of uranium ranged from 10 to 400 mg/dm3. The adsorption of uranium followed Langmuir adsorption isotherm and according to quasi-second order kinetic equation. The calculated values of ΔH°, ΔS°, and ΔG° indicated that the biosorption process was endothermic and spontaneous. Based on FT-IR spectra it may be concluded that hydroxyl, carbonyl, P–O and Si=O groups are the main active sites.

5

Effects of hole-perpendicularity error on joint stiffness of single-lap double-bolt composite joints

Liu X., Yang Y., Gao H., Bao Y., Li R., Chen L.

Engineering Transactions

|

2017

|

Vol. 65, iss. 2

289--305

EN

To investigate the influence of hole-perpendicularity error on stiffness of single-lap doublebolt composite joints, a finite element model was first created and validated by using the analogical mass-spring based model proposed by McCarthy et al. The model was then modified by introducing hole-perpendicularity error, with which the influences of hole-perpendicularity error, which is represented by hole-titling angle, hole-tilting direction, and bolt torque on the joint stiffness are studied. It is found that the hole-tilting direction causes the joint stiffness to either increase or decrease, which depends on the relation between the hole-tilting direction and the loading orientation. In addition, the hole-tilting angle strengthens the influence of hole-tilting direction and the bolt torque plays the most important role among the three factors in affecting the joint stiffness.

6

Friction and Wear Behavior of 201HT Cast Aluminum Alloy with Various Competitive Material

Li R., Chen L. J., Su M., Zeng Q., Li H., Liu Y.

Archives of Foundry Engineering

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2017

|

Vol. 17, iss. 2

55--62

EN

The friction and wear properties of 201HT aluminum alloys and the corresponding competitive coupons were tested on an electro-hydraulic servo face friction and wear testing machine (MM-U10G). The microstructures of the competitive coupons were investigated by scanning electron microscopy (SEM) and consequently the corresponding friction and wear mechanisms were studied. The results demonstrated that: (1) the best competitive material of friction and wear performance of the 201HT was the 201HTC. (2) the 201HTC modified by carbon following the initial mill for oil storage of the micro-groove to be produced, increased the corresponding lubrication performance reduced the friction coefficient and wear rate effectively. (3) the 201HT-201HTC could obtain both better friction and wear mainly due to the initial process of grinding following the 201HT plastic deformation occurred in the surface and the formation of a series of re-melting welding points, whereas the 201HT material hardness would be similar to the 201HTC material hardness, which led into the competitive material friction and wear performance improvement.

7

Vertical distribution of nearshore flow velocity

Li Ch., Fu X., Li R., Dai L., Chen P.

Polish Maritime Research

|

2016

|

S 1

104--108

EN

In this paper, a new exponential formed vertical distribution of nearshore flow velocity is constructed, which is simpler in form and more suitable for engineering application. The physical meaning of the new formula is more specific than that of Soulsby. Compared with those logarithmic formed ones, the new one does not need the maximum velocity and only needs the mean velocity in vertical, which gives it better engineering practicability. Apply the new formula to Jiangsu coastal area and compare the results with that of Soulsby whose results show the new formula agrees better with the measured flow velocity, which reasonably reflects the basic principles of vertical distribution of flow velocity.

8

Biomechanical and fluid flowing characteristics of intervertebral disc of lumbar spine predicted by poroelastic finite element method

Guo L.-X, Li R., Zhang M.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 2

19--29

EN

Purpose: This study is to reveal the deformation of intervertebral disc (IVD), the stress distribution of solid phase and liquid phase, the variation of fluid flux and flow velocity in lumbar spine and the influence of different permeability parameters on them under intermittent compressive loading. Methods: A poroelastic FEM of L4-L5 is assigned with different permeability parameters to analyze the deformation, stress distribution and fluid convection under intermittent compressive loads. Results: The results show that the pore pressure of IVD decreases with time, but the effective stress increases under intermittent compressive loads. The axial and radial strain will increase and fluid loss will recover at a more rapid rate if the permeability of endplate increases during unloading period. The velocity vectors show that most of the liquid in the disc flows into vertebrae through endplates and only a small quantity of liquid flows through the annulus fibrosus at the loading step, however, at the unloading step, almost all the liquid flowing into IVD is through the endplates. Conclusions: The changing rate of pore pressure and effective stresses of nucleus pulposus and annulus fibrosus with higher permeability is smaller than that with smaller permeability. The degenerated endplate (with low permeability) yields high flow velocity decreasing gradient, which might impede liquid inflowing/outflowing smoothly through the endplates. The fluid flowing velocity in loading phase is faster than that in unloading phase, so a short resting time can relieve fatigue, but could not recover to the original liquid condition in IVDs.

9

A delay reliability estimation method for Avionics Full Duplex Switched Ethernet based on stochastic network calculus

Wu Z., Huang N., Li R., Zhang Y.

Eksploatacja i Niezawodność

|

2015

|

Vol. 17, no. 2

288--296

EN

The delay reliability estimation is required in order to guarantee the real-time communication for avionics full duplex switched Ethernet (AFDX). Stochastic network calculus (SNC) can be applied to estimate the reliability with a delay upper bound. However, only linear deterministic traffic envelope function is used to bound its traffic, which cannot represent the traffic randomness and is far from practice. In this paper, a stochastic traffic envelope function, which randomizes the input of SNC, is proposed to solve the problem. A new probabilistic algorithm is derived to estimate the delay reliability based on stochastic envelope functions. A test was conducted to demonstrate our method on an AFDX testbed, and the test results verify that the estimation of delay reliability via our algorithm is much closer to the empirical estimation.

PL

Ocena niezawodności czasu transmisji (czasu opóźnienia) jest niezbędną procedurą gwarantującą komunikację w czasie rzeczywistym za pośrednictwem przełączanej pokładowej sieci ethernetowej typu AFDX (Avionics Full Duplex Switched Ethernet), która umożliwia równoczesną transmisję dwukierunkową. Stochastyczny rachunek sieciowy (SNC) można stosować do oceny niezawodności przy zadanej górnej granicy opóźnienia. Do tej pory jednak, do ograniczania ruchu telekomunikacyjnego stosowano tylko liniową deterministyczną funkcję obwiedni (traffic envelope), która nie oddaje losowości ruchu telekomunikacyjnego i odbiega dalece od rzeczywistości. W niniejszej pracy zaproponowano rozwiązanie tego problemu wykorzystujące stochastyczną funkcję obwiedni ruchu telekomunikacyjnego. Wyprowadzono nowy algorytm probabilistyczny, który pozwala ocenić niezawodność czasu transmisji na podstawie funkcji obwiedni. Przeprowadzono badanie, w ramach którego testowano zaproponowaną metodę w środowisku testowym AFDX; wyniki testu pokazują, że ocena niezawodności czasu transmisji z wykorzystaniem zaproponowanego przez nas algorytmu jest znacznie bardziej zbliżona do estymacji empirycznej.

10

EMD Method Applied to Identification of Logging Sequence Strata

Zhao N., Li R.

Acta Geophysica

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2015

|

Vol. 63, no. 5

1256--1275

EN

In this work, we compare Fourier transform, wavelet transform, and empirical mode decomposition (EMD), and point out that EMD method decomposes complex signal into a series of component functions through curves of local mean value. Each of Intrinsic Mode Functions (IMFs - component functions) contains all the information on the original signal. Therefore, it is more suitable for the interface identification of logging sequence strata. Well logging data reflect rich geological information and belong to non-linear and non-stationary signals and EMD method can deal with non-stationary and non-linear signals very well. By selecting sensitive parameters combination that reflects the regional geological structure and lithology, the combined parameter can be decomposed through EMD method to study the correlation and the physical meaning of each intrinsic mode function. Meanwhile, it identifies the stratigraphy and cycle sequence perfectly and provides an effective signal treatment method for sequence interface.

11

An Online Monitoring System of Corona Loss of High Voltage Transmission Lines Based on Metalized Membrane Method

Luo Y., Liu H., Wang M., Xin X., Zhang Y., Li R., Wang G., Wu J., Bai X.

Przegląd Elektrotechniczny

|

2013

|

R. 89, nr 10

217-220

EN

An online monitoring system of corona loss of high voltage transmission lines based on metalized membrane method is developed in this paper. The system includes 3 components: the upper computer, the conductor voltage acquisition module and the corona leakage current acquisition module. The corona leakage current acquisition module is set on the high voltage line. The transmission line is covered by a certain length of thin metalized membrane . The sampling resistance is put paralleling between metal layer and bundle conductor. The conductor voltage acquisition module is set in transformer substation. The two modules are synchronized by the rising edge of Pulse Per Second (PPS) emitted by Global Position System (GPS), and the data is sent to the public port of mobile telephone network by General Packet Radio Service (GPRS). The remote upper computer gets the data and calculates corona loss of each bundle conductor by visiting public port. The experiment results show that the system can monitor the corona loss accurately. The whole study is helpful in the further research of UHV transmission line’s corona in different environment and weather.

PL

Zaprezentowano metodę monitorowania strat powodowanych ulotem (wyładowaniem koronowym) w liniach transmisyjnych wysokiego napięcia. Do tego celu wykorzystano metalizowaną membranę. Układ składa się z trzech modułów: komputera, systemu akwizycji napia) ęcia i systemu akwizycji prądu ulotu. Linia transmisyjna jest pokryta na pewnej długości cienką metalizowaną membraną. Do lokalizacji ulotu zastosowano moduł GPS a do transmisji danych moduł GPRS.

12

Multidimensional independent subspace analysis by natural gradient

Wang F., Zhang L., Li R., Zhou Y., Liu N.

Przegląd Elektrotechniczny

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2012

|

R. 88, nr 9b

51-54

EN

Multidimensional Independent Subspace Analysis (MISA) as an extended Independent Component Analysis (ICA) method has been considered. The general and detailed definition, existence, uniqueness, separability of the MISA model are given and the relationships between ICA and MISA are also discussed. The natural gradient separation algorithm and corresponding simulation results for MISA are constructed based on the maximum likelihood theory and natural gradient method.

PL

W artykule zaprezentowano metodę MISA – multidimensional independent subspace analysis. Przedstawiono też metode IOCA – independent component analysis. Opracowano algorytm separacji – natural gradient separation algorithm.

13

Effects of saline-alkaline stress on early growth strategy and colonization success of Flaveria bidentis ( L.) Kuntze (Asteraceae ) - a new exotic plant in Northern China

Chai M., Shi F., He K., Li R., Cao D., He Z.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

559-565

EN

Flaveria bidentis, an annual grass native to South America, has invaded into many countries all over the world, including South Africa and Egypt in Africa, Britain and France in Europe, Japan in Asia, and Australia. In China, this plant species has been widely distributed in Hebei province since 2001 of its first discovery in Tianjin. In salinized soil of northern China, F. bidentis has formed mono dominant communities owing to its opportunistic characteristics. In this study, we investigated germination rate, germination energy, germination index and vigor index in response to different saline-alkaline stresses. Lengths of seedling, hypocotyl, and radicle were also examined. During germination process, germination rate, germination energy, germination index, and vigor index decreased due to higher salinity and alkalinity (pH). Hypocotyl elongation was stimulated at low salinity and alkalinity, but decreased with increasing salinity and alkalinity. The lengths of radicle and seedling were inhibited sharply with increasing salinity and alkalinity. These results suggest that a reciprocal enhancement between salt stress and alkaline stress was a characteristic feature during seed germination of F. bidentis. Ungerminated seeds resumed to germinate after transferred to distilled water, indicating that seeds remained viable during their exposure to saline-alkaline stresses. Stepwise regression analysis indicated that the effects of salinity, alkalinity (pH), and buffer capacity on seed germination and seedling growth were significantly different in magnitude. Salinity and alkalinity (pH) were the dominant factors in seed germination and seedling growth of F. bidentis respectively. Further, the results of this study suggest that F. bidentis has developed excellent adaptative strategy in its early stage of life cycle which partially explains its current invasion success in northern China.

14

Analytic bending solutions of rectangular cantilever thin plates

Tian B., Zhong Y., Li R.

Archives of Civil and Mechanical Engineering

|

2011

|

Vol. 11, no 4

1043-1052

EN

Analytic bending solutions of rectangular cantilever thin plates subjected to arbitrary loads are derived using the double finite integral transform method. Since only the basic governing equations of the plates are used and there are no predetermined functions, the present method overcomes the deficiency of the conventional semi-inverse methods thus serves as a completely rational model in solving plate bending problems. The method can be extended to more boundary value problems of plates such as buckling and vibration.

PL

W pracy sformułowano analityczne rozwiązania dotyczące zginania prostokątnych, wspornikowych płyt cienkich poddanych dowolnym obciążeniom przy zastosowaniu metody podwójnej, skończonej transformaty całkowej. Ponieważ zastosowano tylko podstawowe równania płyt, zaprezentowana metoda przezwycięża niedobór konwencjonalnych metod semi-odwrotnych i może służyć jako całkowicie wymierny model przy rozwiązywaniu problemów zginania płyt. Zaprezentowana metoda może być rozszerzona na dalszą klasę problemów brzegowych płyt w zakresie ich wyboczenia oraz drgań.

15

Praktyczne podejście do oceny niezawodności aplikacji sieciowych

Li R., Kang R., Huang N., Chen W., Chen Y.

Eksploatacja i Niezawodność

|

2009

|

nr 4

17-27

PL

Wiele różnych aplikacji może być obsługiwanych przez tę samą sieć. Wymagania użytkowników i kryteria uszkodzeń mogą być odmienne dla różnych aplikacji. Ocena sieci winna być przeprowadzana z punktu widzenia aplikacji. W niniejszym artykule, zaproponowano metodologię oceny niezawodności aplikacji sieciowych opartą na indeksach warstwowych (layered indices). Pierwszym krokiem w omawianej metodzie jest osobne obliczenie niezawodności poszczególnych aplikacji w sieci. Następnie ocenia się niezawodność sieci biorąc pod uwagę związki pomiędzy różnymi aplikacjami. Jako swój wkład niniejszy artykuł (1) przedstawia naukową i praktyczną metodę oceny niezawodności aplikacji sieciowych; (2) tworzy hierarchiczną strukturę do oceny niezawodności aplikacji sieciowych; (3) proponuje i analizuje cztery kluczowe technologie-doboru komponentów, upraszczania sieci, modelowania profilu aplikacji oraz oceny niezawodności aplikacji; (44) ilustruje proponowany proces oceny na przykładzie sieci komputerowej.

EN

Many different applications may be handled by the same network. For different applications, the user requirements and failure criterions may be different. The network reliability assessment needs to be conducted from the "application" point of view. In this paper, a methodology for network application reliability assessment based on layered indices is proposed. Firstly, the individual application reliability is calculated for each application on the network. Then the network reliability is evaluated considering the relationships among different applications. The contributions of this paper are: (1) a scientific and practical network application reliability assessment method is proposed based on network applications; (2) a hierarchical structure for network application reliability assessment is constructed; (3) four key technologies, component selection, network simplification, application profile modeling, and application reliability assessment, are proposed and analyzed; (44) a computer network is used to illustrate the proposed assessment process.

16

Thermodynamics of denaturation of proteins in metal chelate chromatography

Li R., Chen G., Wang Y.

Chemia Analityczna

|

2008

|

Vol. 53, No. 2

253-261

EN

Thermal behavior and thermodynamics of denaturation of proteins in metal chelate chroma-tography (MCC) were investigated at 15-85°C. The experimental results showed that there is a fixed thermal transition temperature for each protein in a chromatographic process. At this temperature a protein changes its conformation. The standard enthalpy change (ΔH") and the standard entropy change (ΔS0) accompanying thermal denaturation of proteins in a chromatographic system were determined using van't Hoff relationship (In k vs 1/T). It was proposed that the conformational change of a protein can be judget using AS" and the standard free energy change (ΔG°). Linear relationship between ΔH" and ΔS0 can be used to determine protein's retention mechanism in MCC. Based on the values of the compensation temperature (p) and entropy of the conformational change (Δ(ΔS°)), thermostability of proteins in cation-exchange chromatography (CEC) and MCC was discussed.

PL

Badano zachowanie się i termodynamikę denaturacji białek w chromatografii na chelatach metali (MCC) w zakresie temperatur 15-85°C. Badania wykazały, że dla każdego białka w procesie chromatograficznym istnieje ustalona temperatura przejścia, w której białko zmienia konformację. Wyznaczono zmiany standardowej entalpii (ΔH°) i standardowej entropii (ΔS") towarzyszące termicznej denaturacji białek w układzie chromatograficznym, przy użyciu zależności van't Hoffa (In k vs l/T). Zaproponowano ilościowe określenie zmian konformacyjnych za pomocą AS" oraz standardowej zmiany energii swobodnej (ΔG").Mechanizm retencji białka w MCC można określić posługując się liniową zależnością między ΔH° i ΔS". Przedyskutowano problem odporności termicznej białek w chromatografii kationowymiennej (CEC) oraz w MCC w oparciu o wartości temperatury kompensacji (P) i entropii zmian konformacyjnych (Δ(ΔS°)).

17

Determination of trace amount of nitrite by fluorescent quenching method with phenosafranine enhanced by ß-cyclodextrin and its derivatives

Jiang Z. T., Guo Y. X., Li R.

Chemia Analityczna

|

2008

|

Vol. 53, No. 4

569-582

EN

A new fluorescent quenching method has been developed for the determination of nitrite in food and water samples. The method is based on the reaction between nitrite and pheno-safranine (PS), which is used as an emission reagent and can react with nitrite to form a weakly-fluorescent compound in 0.02 mol L-1 hydrochloric acid. The sensitivity is largely enhanced in the presence of cyclodextrins (CDs) because of complexation. The effect of β-cyclodextrin (β-CD) and its three derivatives was compared and HP-p-cyclodextrin (HP-p-CD) was most effective. The excitation and emission of fluorescence were at wavelengths 530 and 608 nm, respectively. In the presence of HP-β-CD, the relationship between the fluorescence intensity and nitrite concentration was obtained up to 2.2 μg ml-1. The detection limit was 0.90 ng ml-1. hi the presence of 20 coexistent ions no serious interferences for most ions were observed. The method has been applied to determine nitrite in meat products, potato and water samples with satisfactory results.

PL

Opracowano nową metodę polegającą na tłumieniu fluorescencji azotanów(III) w próbkach wody i żywności. Metoda polega na reakcji azotanów(IH) z fenosafraniną (PS), która jest stosowana jako odczynnik powodujący fluorescencję reagujący z azotanami(III) osłabiającymi fluorescencję w 0,02 mol L-1 roztworze kwasu chlorowodorowego. Czułość reakcji znacznie się zwiększa w obecności cyklodekstryn (CD) w wyniku reakcji kompleksowania. Porównano efekt działania β-cyklodekstryny (β-CD), i trzech jej pochodnych. Najskuteczniejsze działanie zaobserwowano w obecności hydroksypropylo-p-cyklodekstryny (HP-β-CD). Długość fali promieniowania wzbudzającego i emitowanego wynosiła odpowiednio 539 i 608 nm. W obecności HP-β-CD uzyskano liniową zależność natężenia fluorescencji od stężenia azotanów(III) w zakresie do 2,2 μg. Granica wykrywalności wynosiła 0,9 ng mL-1. Nie obserwowano interferencji w obecności większości obcych jonów. Metodę zastosowano z powodzeniem do oznaczania azotanów (III) w próbkach produktów mięsnych, ziemniaków i wody.

18

Determination of manganese in food by polymer-phase fluorescence quenching method with eosin in the presence of phenanthroline

Jiang Z. T., Li R.

Chemia Analityczna

|

2008

|

Vol. 53, No. 5

659-671

EN

A sensitive and selective polymer-phase fluorescence quenching method for determination of trace amounts of manganese in food samples has been developed. The method is based on the reaction between manganese and eosin in the presence of phenanthroline to form a weak-fluorescence compound at pH 8.2. The fluorescence intensity was measured in 5 mm quartz cells at excitation and emission wavelengths of 533 and 550 nm, respectively. There was a satisfactory linear relationship between the fluorescence quenching and concentration of manganese in the range 0.2-3.5 μg in 25 mL of sample solution (i.e. 8-140 μg L-1). Detection limit was 0.03 μg for 25 mL of sample solution and RSD was 1.9%. Coexisting ions did not interfere with the reaction of eosin with manganese. The proposed method was applied to the determination of trace amounts of manganese in millet, black rice, and tea with satisfactory results.

PL

Opracowano czułą i selektywną metodę gaszenia fluorescencji w fazie polimerowej do oznaczania śladowych ilości manganu w żywności. W metodzie wykorzystano reakcję manganu z eozyną w obecności renantroliny. w wyniku której powstaje przy pH 8,2 słabo fluoryzujący związek. Intensywność fluorescencji mierzono w 5 mm komórce kwarcowej przy dł. fal wzbudzenia i emisji wynoszących odpowiednio 533 i 550 nm. Otrzymano dobrą zależność liniową między gaszeniem fluorescencji i stężeniem manganu w zakresie 0.2-3.5 μg w 25 mL roztworu próbki (czyli 8-140 μ g L-1).Wykrywalność wynosiła 0.03 μ g w 25 mL roztworu próbki, a względne odchylenie standardowe - l ,9%. Współ-występujące jony nie przeszkadzały w reakcji eozyny z manganem. Zaprapowaną metodę zastosowano do oznaczania śladowych ilości manganu w prosie, czarnym ryżu i w herbacie uzyskując dobre rezultaty.

19

Quantum Chemistry Studies on Bis(p-aminobenzoato)–lead(II) Complex [Pb(C6H4NH2COO)2]

Zhao P., Xu J., Li R., Zhang W., Cai Z.

Polish Journal of Chemistry

|

2007

|

Vol. 81, nr 1

85-93

EN

The title complex, bis(p-aminobenzoato)–lead(II) [Pb(C6H4NH2COO)2], has been optimized at B3LYP/LANL2DZ level of theory and the calculated results show that the lead(II) ion adopts a four-coordinate geometry. The analyses of NPA and Mulliken atomic charge distributions indicate that during the process of the formation of this compound, both aminobenzoato ligands transfer their negative charges to the lead(II) ion. The lead atom and oxygen atoms form covalent bonds by using their 6p and 2p orbitals, respectively. The calculations of electronic spectra of the title complex show that there exist four absorption bands and the electronic transitions are mainly derived from the contributions ofboth an intraligand* transition and ligand-to-metal charge transfer (LMCT) transitions. The thermodynamic properties of the studied compound at different temperatures have been calculated and the corresponding relations between the properties and temperatures have also been obtained. The calculation of the second order optical nonlinearity has been carried out, and the molecular hyperpolarizability of the title complex is 7.61379x10–30 esu.

20

Experimental and Theoretical Study on 3-Benzyl-4-phenyl-1,2,4-triazole-5-thione

Zhao P., Li R., Xu J., Zhang W.

Polish Journal of Chemistry

|

2007

|

Vol. 81, nr 8

1495-1503

EN

The 3-benzyl-4-phenyl-1,2,4-triazole-5-thione was synthesized and examined by elementary analysis, IR and electronic spectra. Density functional theory calculations of the structure, natural bond orbitals and thermodynamic functions of the title compound were performed at B3LYP/6-311G** level of theory. Vibrational frequencies were predicted, assigned and compared with the experimental data, and they are supported by the experimental data. Electronic absorption spectrawere calculated by the time-dependent density functional theory (TD-DFT), which indicates that the two absorption bands are mainly derived from the contribution of bands *. The calculation of the second order optical nonlinearity was carried out, giving value of molecular hyperpolarizability equal to 4.025ź10–30 esu. These calculated results were also compared with results obtained for a similar molecule, 4-phenyl-3-[(1,2,4-triazol-1-yl)methyl]-triazole-5-thione, reported earlier by this group.