The photosynthetic pathway of plant species collected at Menyuan, Henan, and Maduo sites, east of Tibetan Plateau, China, during the growing season were studied using stable carbon isotopes in leaves. The 232 samples leaves analyzed belonged to 161 species, 30 families, and 94 genera. The δ13C values (from -24.6 to -29.2 ‰) indicated that all the considered species had a photosynthetic C3 pathway. The absence of plant species with C4 photosynthetic pathway might be due to the extremely low air temperature characterizing the Tibetan Plateau. The average δ13C value was significantly (p<0.05) different between annuals and perennials at the three considered study sites. Hence the longer-lived species had greater water-use efficiency (WUE) than shorter-lived species, that is, longer-lived species are better adapted to the extreme environmental conditions of the Tibetan Plateau. and M. C. Li ... [et al.].
Field experiments were conducted in Sicily (south Italy) during two seasons to characterize by chlorophyll (Chl) fluorescence four genotypes (Spunta, Sieglinde, Daytona, and Ninfa) of potato (Solanum tuberosum L.) for off-season production during plant aging and to analyse the possible relation between Chl parameters and tuber yield. Chl fluorescence parameters [initial fluorescence (F0), maximum fluorescence (Fm), Fv/Fm, time in which maximal fluorescence occurs (Tmax)] gained from Kautsky kinetics and Chl content were measured weekly, from 5th to 6th leaf appearance to beginning of plant senescence in the first season and to full plant senescence in the second season. F0 and Fv/Fm were the most reliable Chl fluorescence parameters for the definition of genotypic differences while Chl content and Tmax were the most reliable Chl parameters to predict plant aging. Tuber yield was highly correlated with Chl content, Tmax, F0, and Fm.
Catalytic test reaction of methylbutynol (MBOH) conversion was applied to investigation of natural clays and non-clay minerals from Jordanian (bentonite, kaolinite, diatomite, zeolit e) and Russian (palygorskite, kaolinite, hydromica) deposits as well as H-ZSM-5. Palygorskite and kaolinite containing samples have shown the highest catalytic activity. Conversionove r Jordanian clay minerals decreased in the order: zeolite > bentonite > red kaolinite > white kaolinite > diatomite that agreed to change of acidity, surface area of samples. Sufficient deactivation was observed for H-ZSM-5, kaolinite and hydromica due to adsorption of secondary product in micropores of raw minerals. Products of both acidic and basic pathways of test reaction were formed indicating the presence of acid and basic sites on clays surface, apart from acidic catalyst H-ZSM-5. Theyield ratio of acidic to basic products was above the unity for zeolite, bentonite, red kaolinite, and palygorskite; equal to unity for diatomite and hydromica, and less then unity for white kaolinite. It was observed for kaolinite containing sample that high activation temperature increased conversion of MBOH owing to fo rmation of additional basic sites as a result of mineral dehydroxylation. Rise of montmorillonite content from 30 to 80 % provided 91-97 % of MBOH conversion., Lyudmila Novikova, Larisa Belchinskaya, Frank Roessner and Murad Alsawalha., and Obsahuje bibliografické odkazy
A total of 23 genotypes belonging to seven tropical food yams and two wild relative species of different origin and coming from two sampling ecological zones (the Republic of Benin in Africa and Guadeloupe in the Caribbean) was analysed for their 13C content. The δ13C values for all yam samples (from -25.39 and -30.07 ‰) indicated that all species had a C3 photosynthetic type. and D. Cornet, J. Sierra, R. Bonhomme.
Carotenoids (Car) regulate energy flow in photosynthesis by a specific Car-chlorophyll (Chl) interaction in the singlet-excited states, leading to a reduction in Chl fluorescence. We studied quenching of Chl a-fluorescence in benzene by trans-β-carotene. Non-linear analysis of the quenching process enables to explain the possible molecular mechanism leading to the de-excitation of Chl a. The fluorescence intensity was measured at 670 nm for excitation wavelengths of 380, 430, 640, and 650 nm. The β -carotene concentrations ranged from 4×10-5 M to 5×10-3 M. When the samples were excited at 640 and 650 nm, the Stern-Volmer plots showed that the quenching process has high rate constants, hence β-carotene is a very efficient quencher. Two different types of quenching process could take place. and D. M. Gazdaru, B. Iorga.
Morphological characteristics of ripples are analyzed considering bed surfaces as two dimensional random fields of bed elevations. Two equilibrium phases are analyzed with respect to successive development of ripples based on digital elevation models. The key findings relate to the shape of the two dimensional second-order structure functions and multiscaling behavior revealed by higher-order structure functions. Our results suggest that (1) the two dimensional second-order structure functions can be used to differentiate the two equilibrium phases of ripples; and (2) in contrast to the elevational time series of ripples that exhibit significant multiscaling behavior, the DEMs of ripples at both equilibrium phases do not exhibit multiscaling behavior.
Decarburization as a common adverse effect at manufacturing and processing steel semiproducts. Loses caused by surface decarburization. Initial basis for solution of GAČR project - magnetic diagnostics of decarburization. Selection of steel, temperature and exposition times at oxidizing atmosphere. Surfaces with oxide layers, after pickling, shot-blasted. Surface diagnostics by x-ray diffraction - crystals, structure, texture, stregthening, internal stress; decarburization evaluation after ČSN EN standard. Intention of project solution. and Oduhličení jako běžný doprovodný nepříznivý jev při výrobě a zpracování ocelových polotvarů. Ztráty z titulu oduhličení povrchů. Výchozí podklady pro řešení projektu GAČR - magnetické diagnostiky oduhličení. Volba oceli, teploty a časy expozice v oxidační atmosféře. Povrchy s vrstvami kysličníků, po moření, upravené tryskáním. Diagnostika povrchu RTG difrakcí - krystaly, struktura, textura, zpevnění, vnitřní pnutí; hodnocení oduhličení podle ČSN EN. Záměr řešení projektu.
Prezentovaný príspevok uvádza hlavné charakteristiky fluorescenčného farbiva merocyanínu 540 (MC 540), jeho interakciu s biologickými membránami a prehĺad jeho biofyzikálnych a biomedicínskych aplikácií. Dôraz je kladený na najnovšie možnosti aplikácií MC 540, a to v cytometrickej detekcii kapacitácie spermií a prokoagulačnej aktivite trombocytov, v elektroforetickej analýze alifatických karboxylových kyselín a peptidov a v optických senzoroch pro stanovenie amónia v pôde a vodných sedimentoch., Libuša Šikurová., and Obsahuje seznam literatury
This work is focused on the laser ablation synthesis of Cu/Ag nanostructures in aqueous solution of acetic acid containing chitosan as capping agent. A two step process taking place in a flowing cell using femtosecond laser pulses was developed to consecutively ablate each metal. As-prepared nanomaterials were morphologically and spectroscopically characterized by transmission electron microscopy, UV-VIS and X-ray photoelectron spectroscopy. Application of Cu/Ag nanomaterials is envisaged as antibacterial materials for food packaging. and Článek se zaměřuje na syntézu Cu/Ag nanostruktur laserovou ablací ve vodném roztoku kyseliny octové obsahujícím chitosan, který plní funkci stabilizačního media. Dvoukroková ablace, probíhající v průtokové cele za použití femtosekundových laserových pulsů, byla navržena tak, aby byla umožněna následná ablace kovů. Takto připravené nanomateriály byly morfologicky a spektroskopicky charakterizovány pomocí transmisní elektronové mikroskopie, UV-VIS a fotoelektronové spektroskopie. Jako případné aplikace Cu/Ag nanostruktur lze uvést antibakteriální obalové materiály potravin.
The microstructure of transparent yttrium-aluminum garnet (YAG) ceramics is characterized using different microstructural descriptors, with special focus on grain size numbers. Both linear and planar grain size numbers are used to describe the dependence of the average grain size on Yb dopant content (0 - 10 at.%),sintering additive (tetraethyl orthosilicate, TEOS) content (0.3 - 0.5 wt.%) and firing time. Although the two grain size numbers are very close for the materials studied (with ratios very close to unity, around 0.987 ± 0.109), these two numbers are principally independent and provide complementary microstructural information. Their relations to other microstructural descriptors (interface density, mean curvature integral density, mean chord length, Jeffries size) are discussed throughout the text. It isfound that Yb doping of more than 3 at.% has a grain-growth-inhibiting effect (after sufficiently long firing times), but differences in the TEOS content between 0.3 and 0.5 wt.% do not have any sensible effect. The largest effect on the microstructure is exerted by the firing time (with prolonged firing times leading to grain growth), but with higher Yb doping the effect of firing time on the grain size becomes less pronounced: for YAG samples without Yb doping, increasing the firing time by a factor of 8 (from 2 h to 16 h), deceases the grain size number by 33.2 - 35.0 %, whereas with a Yb dopant content of 10 at.%, the corresponding decrease in the grain size number is only 8.7 - 10.0 %. These findings are fully corroborated using the other microstructural descriptors. and Mikrostruktura transparentní keramiky YAG (yttrium-aluminium granát) byla charakterizována pomocí různých deskriptorů se zaměřením na velikostní čísla zrn. Jak lineární, tak planární velikostní čísla zrn byla použita k popisu závislosti průměrné velikosti zrn na koncentraci ytterbitého (Yb) dopantu (0 - 10 at. %), koncentraci slinovací přísady - tetraethylorthosilikát, TEOS (0,3 - 0,5 hm. %) a době slinování. Přestože obě tato velikostní čísla zrn mají podobné hodnoty u studovaných materiálů (jejich poměr je téměř jednotkový, 0,987 ± 0,109), jsou principiálně nezávislá a poskytují vzájemně se doplňující informace o mikrostruktuře. Rovněž jejich vztah k dalším mikrostrukturním deskriptorům (hustota rozhraní, hustota integrálu středního zakřivení, střední délka úseků, Jeffriesova velikost) je diskutován. Bylo zjištěno, že obsah Yb větší než 3 at. % potlačuje při delší době slinování růst velikosti zrn. Rozdíly v koncentraci TEOSu v rozmezí 0,3 - 0,5 hm. % nemají žádný prokazatelný vliv na velikost zrn. Nejvýraznější vliv na mikrostrukturu má různá doba slinování, kdy prodloužená doba slinování pochopitelně vede k růstu zrn, nicméně se zvyšujícím se obsahem Yb není tento růst tak výrazný: pro YAG vzorky bez dopování Yb vede osminásobné zvýšení doby slinování (ze 2 h na 16 h) k poklesu velikostních čísel zrn o 33,2 - 35,0 %, kdežto s obsahem Yb 10 at. % je odpovídající snížení velikostních čísel pouze 8,7 - 10,0 %. Tato zjištění odpovídají výsledkům získaným pomocí jiných mikrostrukturních deskriptorů.