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1
Content available Synthesis, Characterization and Thermal Decomposition of a New Energetic Salt of 1H,1′H-5,5′-Bistetrazole-1,1′-diol
Xiao L., Jin B., Shang Y., Liu Q., Guo Z., Peng R.
Central European Journal of Energetic Materials
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2018
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Vol. 15, no. 3
405--419
EN
1,1-Dimethylbiguanidium 1H,1′H-5,5′-bistetrazole-1,1′-diolate (MGBTO), a novel nitrogen-rich energetic salt, was synthesized by cation exchange. Its structure was characterized by elemental analysis, FTIR, NMR, DTA and TG-DTG. Single crystal X-ray diffraction analysis revealed that MGBTO was crystallized in the monoclinic space group C2/c. Thermal analysis demonstrated that its thermal stability extended up to 531.1 K. The nonisothermal kinetic and apparent thermodynamic parameters of the exothermic decomposition of MGBTO were determined by the Kissinger and Ozawa methods. Its detonation velocity and detonation pressure were calculated on the basis of the Kamlet-Jacobs equation and were 6342 m·s–1 and 15.78 GPa, respectively. The impact and friction sensitivities of MGBTO were quantified using standard BAM (10 kg drop hammer) procedures. The results revealed that the salt has good mechanical sensitivity (FS > 120 N, IS > 40 J), thus indicating its potential applications as an energetic material.
2
Content available Investigation and optimization of use of anionic collectors in direct flotation of bauxite ores
Liu C., Feng A., Guo Z.
Physicochemical Problems of Mineral Processing
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2016
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Vol. 52, iss. 2
932--942
EN
Bauxite is the main raw material for the alumina industry. Direct flotation is the most widely used method for bauxite beneficiation. In this study, a large number of direct flotation tests were carried out using several anionic reagents. The testing concluded that vegetable oil acid (VOA), naphthenic acid (NA) and lauryl polyoxyethylene phosphate (AEP12) were the three outstanding collectors for bauxite direct flotation. ZMC collector was mixed and prepared using VOA, NA and AEP12, in which the mass ratio of VOA, NA and AEP12 was 1:1:0.5. When processing the bauxite ores of the mass ratio of Al2O3 to SiO2 (A/S) = 4.99, the A/S of the final concentrate was 7.08 and the recovery of Al2O3 was 90.22%. When processing ores of A/S = 4.5, the A/S of the final concentrate was 7.04 and the recovery of Al2O3 was 92.16%. Thus, it can be seen that properties and behaviors of the ZMC reagent were remarkable and met the demands of the “Lime-Bayer Process”.
3
Content available The Effect of the Energetic Additive Coated MgH2 on the Power of Emulsion Explosives Sensitized by Glass Microballoons
Cheng Y., Wang Q., Liu F., Ma H., Shen Z., Guo Z., Liu R.
Central European Journal of Energetic Materials
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2016
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Vol. 13, no. 3
705--713
EN
Traditional emulsion explosives, in spite of excellent water resistance, safe handling and good storage performance, have low power problems which seriously hinders their use. In order to improve the power of emulsion explosives, a hydrogen based emulsion explosive was devised. Scanning electron microscope pictures and experimental storage results show that the coating effect and stability of coated magnesium hydride (MgH2) are very good. The power of an emulsion explosive sensitized by glass microballoons was significantly increased (24.30 mm compression of lead block) after adding coated MgH2, compared to only 16.10 mm compression when not added. Thus emulsion explosives with coated MgH2 as an energetic additive have many potential applications.
4
Content available Distribution and sources of n-alkanes in surface sediments of Taihu Lake, China
Yu Y., Li Y., Guo Z., Zou H.
Archives of Environmental Protection
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2016
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Vol. 42, no. 1
49--55
EN
The last study on n-alkanes in surface sediments of Taihu Lake was in 2000, only 13 surface sediment samples were analysed, in order to have a comprehensive and up-to-date understanding of n-alkanes in the surface sediments of Taihu Lake, 41 surface sediment samples were analyzed by GC-MS. C10 to C37 were detected, the total concentrations of n-alkanes ranged from 2109 ng g−1 to 9096 ng gg−1 (dry weight). There was strong odd carbon predominance in long chain n-alkanes and even carbon predominance in short chain n-alkanes. When this finding was combined with the analysis results of wax n-alkanes (WaxCn), carbon preference index (CPI), unresolved complex mixture (UCM), hopanes and steranes, it was considered that the long chain n-alkanes were mainly from terrigenous higher plants, and that the short chain n-alkanes mainly originated from bacteria and algae in the lake, compared with previous studies, there were no obvious anthropogenic petrogenic inputs. Terrestrial and aquatic hydrocarbons ratio (TAR) and C21−/C25+ indicated that terrigenous input was higher than aquatic sources and the nearshore n-alkanes were mainly from land-derived sources. Moreover, the distribution of short chain n-alkanes presented a relatively uniform pattern, while the long chain n-alkanes presented a trend that concentrations dropped from nearshore places to the middle of lake.
5
Content available remote The Ecological Amplitude of Acorus calamus Young Shoots Under Water Level Gradient
Cao Y., Guo Z., Yang Y., Wang G., Xie Z.
Polish Journal of Ecology
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2015
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Vol. 63, nr 4
585--592
EN
This paper analysed the influence of the gradient of water levels (-54–120 cm) on Acorus calamus (A. calamus) young shoots in terms of their growth characteristics (germination rate, basal stem, height and biomass), leaf characteristics (number, area and moisture content), chlorophyll (chl) fluorescence parameters (Fv/ Fm, ETR, qP and qN) and other indicators. Based on a Gaussian model, we determined and quantified the response relationship between A. calamus young shoots and water level. The results showed that the ecological amplitude of water level for A. calamus young shoots was -52.3−141.8 cm, and the optimum range was -3.5−69.3 cm; a variety of indicators suggested that the optimum depth for A. calamus young shoots was from18.8 cm to 49.6 cm. The A. calamus seedling growth characteristics which were sensitive to changes in the water level were the germination rate and biomass. The germination rate was more sensitive to the submergence water depth, but the biomass was obviously influenced by the groundwater depth. Therefore, the A. calamus could be a suitable species for ecological restoration of land/inland water ecotones in lakes, rivers and reservoirs.
6
Content available remote Modelling and Spherical Air Bearing Based Levitation Design of a Novel M-DOF Actuator
Li Z., Guo Z.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 11a
288-291
EN
Supporting and levitation control are important for actuators or motors with complicated structures. Based on the presented configuration design, the simplified torque calculation model and non-linear system dynamic model have been proposed, and spherical air bearing levitation mechanism is developed for alleviating the friction and resistance to improve the dynamic performance of this m-DOF actuator. The fluid field model is built in computational fluid dynamics software. Different structure parameters and conditions are computed and compared with the pressure distribution characteristics. Experiment results show that the actuator can effectively implement 3-DOF motion with the designed levitation modes, and that the proposed approach can be applied to m-DOF actuators of the same kind effectively.
PL
W artykule przedstawiono wyniki prac nad mechanizmem lewitacji w powietrznym łożysku kulistym siłownika typu m-DOF, mających na celu zwiększenie dynamiki poprzez zmniejszenie tarcia i rezystancji. Zaproponowano także uproszczoną metodę obliczania momentu mechanicznego oraz model układu w stanach dynamicznych. Opracowane modele lewitacji zostały poddane weryfikacji eksperymentalnej.
7
Patchy nature of cement and concrete revealed by physical discrete element simulation approach
Stroeven P., He H., Guo Z., Stroeven M.
Inżynieria Materiałowa
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2008
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Vol. 29, nr 4
408-412
EN
Microscopy observations have revealed the physical existence of a so-called patch microstructure in concrete. This paper presents some evidence that patchy nature is also exist in meso-level, such as distribution of aggregate grain and fibers in concrete. Systematic experimental research into dispersion characteristics of "particles" would be time-consuming and thus expensive. Physical discrete element computer simulation (DECS) by concurrent algorithm-based SPACE system is an economic and potentially reliable alternative. Compared with experimental results, it demonstrates the reliability of the applied DECS approach for predicting dispersion characteristics exploration of cementitious materials on different levels of the microstructure. Patchy nature has been revealed by this DECS approach in meso-level and micro-level.
PL
Obserwacje mikroskopowe wykazały istnienie tak zwanej niejednorodności mikrostrukturalnej betonu. Niniejsza praca przedstawia dowody przemawiające za występowaniem tego rodzaju niejednorodności także na poziomie mesostruktury, jak to ma miejsce na przykład w przypadku rozkładu ziaren kruszywa i rozproszonych włókien w betonie. Systematyczne badania naukowe nad poznaniem charakterystyk rozproszenia "ziaren" byłoby bardzo czasochłonne, a co za tym idzie kosztowne. Symulacja komputerowa za pomocą metody elementów dyskretnych (DECS) rzeczywistej budowy struktury betonu z wykorzystaniem programu SPACE, jest ekonomiczną i potencjalnie wiarygodną alternatywą. Porównanie z wynikami badań eksperymentalnych wykazuje wiarygodność zastosowanej metody (DECS) do przewidywania charakterystyk rozmieszczenia składników w materiałach cementowych, badanych na różnych poziomach obserwacji mikrostruktury. Niejednorodność budowy została wykazana za pomocą metody DECS zarówno na poziomie meso, jak i mikrostruktury.
8
Discrete element approach to packing of arbitrary-shaped particles in concrete
He H., Guo Z., Stroeven P., Stroeven M.
Inżynieria Materiałowa
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2008
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Vol. 29, nr 4
403-407
EN
The shapes of real particles using in concrete, from coarse aggregate to mineral admixture, are irregular. The influence of particle shape on behavior of packing is enormous, so on the properties of fresh concrete and matured concrete. Definition of actual grain shape as well as simulation in a discrete element simulation (DES) approach is complicated, however. Spherical grain shape is therefore generally adopted in conventional simulation systems, despite imposing serious limitations. In this paper, a simulation strategy is presented for representation of arbitrary-shaped aggregate grains applied in concrete technology. This simulation approach is also incorporated in a concurrent algorithm-based DES system with the acronym HADES. After assessment of properties pertaining to arbitrary shaped particles, such as mass, centre of mass, and moment of inertia, an example of random mono-sized packing with deferent shapes by DES approach is also revealed. The influence of shape on mono-sized packing behavior is also briefly discussed in this paper.
PL
Rzeczywiste kształty ziaren, wykorzystywanych w produkcji betonu, poczynając od żwiru do mineralnych domieszek, są nieregularne. Ponieważ wpływ kształtu ziaren na sposób ich upakowania jest bardzo istotny, ma on również ogromny wpływ zarówno na właściwości świeżej mieszanki betonowej, jak i betonu stwardniałego. Zdefiniowanie rzeczywistego kształtu ziarna, jak i jego zasymulowanie, w opisie dyskretnym (DES) jest skomplikowane. Z tego względu w tradycyjnych metodach symulacyjnych wykorzystywany jest kulisty kształt ziaren, pomimo iż wiąże się to z istotnymi ograniczeniami. W niniejszej pracy przedstawiono propozycję strategii symulacji dla ziaren kruszywa o dowolnym kształcie. Ten sposób symulacji jest także wykorzystywany w zbliżonym algorytmie, bazującym na metodzie DES, znanym pod nazwą HADES. Po określeniu właściwości charakteryzujących ziarna o przyjętym kształcie, takich jak na przykład masa, środek masy oraz moment bezwładności, przedstawiono przykład losowego upakowania za pomocą metody DES ziaren kruszywa, jednorodnych wymiarowo, ale o zróżnicowanym kształcie. W pracy omówiono pokrótce także wpływ kształtu na jednorodny wymiarowo sposób upakowania ziaren kruszywa w strukturze betonu.
9
Content available remote Real-time face detection and pose estimation for driver monitoring
Guo Z., Yan Y., Hua J., Yang J.
Image Processing & Communications
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2006
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Vol. 11, no 2
83-96
EN
For a driver monitoring system, one of the most important problems to solve is face detection rapidly. This paper presents an efficient approach to achieve fast and accurate face detection in gray level videos. Candidates of face at different scales are selected by finding regions based on Mask Transform (MT). To obtain real one, all the face candidates are then verified by using support vector machines (SVMs) based on Multi-scale 2D Walsh-Hadamard features. Head pose is estimated on the basis of accurate face detection. At last, we analyzed the head pose by a kind of Bilateral-projection Matrix Principle Component Analysis (BMPCA) algorithm proposed. Experimental results on many videos show that the algorithm can detect driver's face rapidly and estimate the head pose accurately. The proposed method is robust to deal with illumination changes, glasses wearing and different head pose with moderate rotations. Experimental results demonstrate its effectiveness.
10
A Facile Synthesis of the Fucosylated N-Linked Glycan Core and Its Application to Solid-Phase Synthesis of CD52 Glycopeptide
Shao N., Guo Z.
Polish Journal of Chemistry
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2005
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Vol. 79 / nr 2
297-307
EN
An efficient synthesis of the fucosylated N-linked core hexasaccharide (23) and its asparagine conjugate (26), as well as their applications to the solid-phase synthesis of an extensively protected glycopeptide (1) of CD52 antigen containing the hexasaccharide, is described. The difficult beta-mannosidic and alfa-fucosidic linkages were achieved by the Crich and in situ anomerization protocols respectively, which offered excellent results. An especially acid-sensitive resin, 2-chlorotrityl resin, was used in the solid-phase synthesis, and the target glycopeptide 1 could be released from the resin by 10% HOAc without affecting the acid-labile protecting groups and fucosidic bond.
11
Content available remote Kinetic spectrophotometric determination of total iron by sequential injection analysis
Feng S., Guo Z., Fan J.
Chemia Analityczna
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2005
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Vol. 50, No. 3
615-623
EN
A new, simple and highly sensitive kinetic spectrophotometric method for the determination of total iron by sequential injection analysis (SIA) has been proposed. The determination was based on the catalytic effect of potassium bromate on the oxidation of diamino-ditolyl. The absorbance of the investigated chemical system, measured at the wavelength of 639 nm, was used to determine the amount of total iron. Chemical and physical conditions for the applied SIA method have been optimized and, after that, the calibration plot was constructed in the analyte concentration range of 0.035-0.700 ug mL-1>. Detection limit of iron was 5 ug L-1>. Relative standard deviation for 11 replicate determinations of 0.25 μgmL-1>Fe(III) was 1.1% at a throughput of 27 samples per hour. The method was applied to the determination of total iron in tea, human hair and pharmaceutical formula tion. The results obtained by the proposed method were compared with those obtained by FAAS. The t-test did not reveal any significant differences between the two methods at the confidence level of 95%.
PL
Zaproponowano nową, prostą i wysokoczułą kinetyczną metodę spektrofotometrycznego oznaczania żelaza całkowitego za pomocą sekwencyjnej analizy wstrzykowej (SIA). Podstawą oznaczania jest katalityczne działanie bromianu potasu na utlenianie diaminoditolilu. Do oznaczania żelaza całkowitego wykorzystano absorbancję badanego układu chemicznego, mierzoną przy długości 639 nm. Zoptymalizowano chemiczne i fizyczne warunki SIA i wyznaczono wykres wzorcowy w zakresie stężenia analitu od 0,035 do 0,700 mg mL-1>. Wykrywalność żelaza wynosiła 5 mg L-1>. Względne odchylenie standardowe dla 11 oznaczeń 0,25 mg mL-1> Fe(III) wynosiło 1,1% przy analizie 27 próbek na godzinę. Metodę zastosowano do oznaczania żelaza całkowitego w herbacie, włosach ludzkich i preparatach farmaceutycznych. Wyniki otrzymane zaproponowaną metodą porównano z otrzymanymi metodą FAAS. Test-t, przy poziomie ufności 95%, nie wykazał wyraźnych różnic obu metod.
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