Monomodal Curves Research Articles

千岛湖次生林优势种植物光合生理生态特性

The main factors that influence community succession in an evergreen broadleaf forest are differences in the ecological adaptability and eco-physiological traits of the various dominant plant species.Studies of the eco-physiological traits of these dominant species allow researchers to better understand the physiological demands and ecological traits of dominant species in their forest habitat and these studies also help researchers to recognize and understand the intrinsic mechanisms involved in forest regeneration and the mechanisms driving ecological succession in an evergreen broadleaf forest at the individual species level.In this study,we used a portable photosynthesis system to determine various physiological parameters associated with plant growth.We investigated the seasonal dynamics of the diurnal variations of photosynthesis,the responses to both light and CO2,and the relative chlorophyll content of the dominant plant species in the secondary forest surrounding Qiandao Lake,Zhejiang,China.The species included Pinus massoniana,Castanopsis sclerophylla,Lithocarpus glaber and Cyclobalanopsis glauca.The results showed the following.(1) Diurnal variations of the net photosynthesis rate(Pn) of P.massoniana exhibited a monomodal curve in all four seasons,while the variations in PnforC.sclerophylla were bimodal in August but had a single curve in the other three time seasons investigated.Diurnal variations of Pnof L.glaber and C.glauca exhibited a typical bimodal curve with obvious "midday depression"in May,August and November but had a monomodal curve in February.(2) The diurnal integral values of Pnof P.massoniana and C.sclerophylla were significantly higher in August than those in the other three seasons,while those of L.glaber and C.glauca were significantly higher in November than those in the other three time periods investigated.The average value of the diurnal integral value of Pnin the four dominant species differed significantly in all four seasons and was ranked in the order of:P.massoniana C.sclerophylla L.glaber C.glauca;(3) Compared with the other three dominant species,for P.massoniana,the light saturation point(LSP),light compensation point,maximum net photosynthetic rate,dark respiration rate(Rd),maximum rate of carboxylation and maximum rate of electron transport were highest in all four seasons,while the apparent quantum yield(AQY) was the lowest.The LSP and Rdof C.glauca were the lowest,while the AQY of C.glauca was the highest in the four seasons.Photosynthetic characteristics of C.sclerophylla and L.glaber were moderate among the four species.(4) In all four seasons,the relative chlorophyll content of C.glauca was the highest among the four dominant species,while that of P.massoniana was the lowest.All these results indicate that P.massoniana and C.sclerophylla are shade intolerant species and moderately shade intolerant species,respectively,while L.glaber and C.glauca are strongly shade tolerant species,although C.glauca is more strongly shade tolerant when compared with L.glaber.Based on these findings,we concluded that P.massoniana and C.sclerophylla will withdraw from the community during the succession.L.glaber and C.glauca will become the dominant species in the secondary forest surrounding Qiandao Lake as these forests mature.

QMRI relaxometry of mandibular bone marrow: A monomodal distribution in sickle cell disease

To identify and characterize sickle cell disease (SCD)-related changes in the composition of mandibular bone marrow using qMRI relaxometry histograms. Thirteen SCD patients and 17 controls underwent brain MR imaging with the mixed turbo spin-echo (TSE) pulse sequence at 1.5T. The mandible was manually segmented and divided into body, angle, ramus, and condyle. T1 and T2 histograms of each mandible were modeled with Gaussian functions. The relaxation time histogram peaks were calculated, and the number of monomodal versus bimodal curves was compared. SCD patients exhibited monomodal distributions on both T1 and T2 histograms, consistent with a composition of predominantly red hematopoietic marrow. Eighty-eight percent of mandibles in control subjects exhibited a bimodal distribution in T1 and all showed a bimodal distribution in T2, indicating mixed but predominantly yellow marrow composition. The second peak in control subjects was shorter in T1 and longer in T2, consistent with yellow marrow composition. Instead of physiological fatty replacement, SCD patients exhibit red marrow persistence in the mandible, likely due to the increased demand for hematopoiesis. This phenomenon can be manifested by a monomodal curve in both T1 and T2 relaxometric histograms.

Investigation on CO 2-induced plasticization in polycarbonate membrane using positron annihilation lifetime spectroscopy

In this study, the microstructural changes in polycarbonate (PC) membranes induced by the CO 2 sorption were investigated using the CO 2 sorption isotherm data and the positron annihilation lifetime spectroscopy (PALS). The effects of the PC exposure to CO 2 at different temperatures and gas pressures on the free-volume distribution were discussed. The distribution at ambient conditions or 5 atm He pressure displayed a monomodal curve, whereas that at different CO 2 pressures showed a bimodal curve, indicating the presence of small and big free-volume sizes due to the serious plasticization caused by CO 2.

Solid acid clay mediated copolymerization of methyl acrylate and 1‐octene: 2D NMR substantiation of predominant alternating comonomer sequence

AbstractMontmorillionite K10 powder presence during radically initiated copolymerization of methyl acrylate (M) and 1‐octene (O) gave copolymers with higher incorporation of alkene unit. Highly viscous and transparent copolymers showed alternation irrespective of the copolymer composition. Increasing the amount of K10 powder increased the total percentage conversion, as well as 1‐octene incorporation. The monomodal curves obtained in gel permeation chromatography (GPC) substantiated that true copolymers were formed. The alternation in the copolymers was authenticated through Heteronuclear Multiple Quantum Correlation (HMQC) experiments in conjugation with Total Correlated Spectroscopy (TOCSY). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2156–2162, 2009

Titanium tetrachloride supported on atom transfer radical polymerized poly(methyl acrylate‐co‐1‐octene) as catalyst for ethylene polymerization

AbstractEthylene polymerizations were performed using catalyst based on titanium tetrachloride (TiCl4) supported on synthesized poly(methyl acrylate‐co‐1‐octene) (PMO). Three catalysts were synthesized by varying TiCl4/PMO weight ratio in chlorobenzene resulting in incorporation of titanium in different percentage as determined by UV‐vis spectroscopy. The coordination of titanium with the copolymer matrix was confirmed by FTIR studies. The catalysts morphology as observed by SEM was found to be round shaped with even distributions of titanium and chlorine on the surface of catalyst. Their performance was evaluated for atmospheric polymerization of ethylene in n‐hexane using triethylaluminum as cocatalyst. Catalyst with titanium incorporation corresponding to 2.8 wt % showed maximum activity. Polyethylenes obtained were characterized for melting temperature, molecular weight, morphology and microstructure. The polymeric support utilized for TiCl4 was synthesized using activators regenerated by electron transfer (ARGET) Atom Transfer Radical Polymerization (ATRP) of methyl acrylate (MA) and 1‐octene (Oct) with Cu(0)/CuBr2/tris(2‐(dimethylamino)ethyl)amine (Me6TREN) as catalyst and ethyl 2‐bromoisobutyrate (EBriB) as initiator at 80 °C. The copolymer poly(methyl acrylate‐1‐octene; PMO) obtained showed monomodal curve in Gel Permeation Chromatography (GPC) with polydispersity of 1.37 and copolymer composition (1H NMR; FMA) of 0.75. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7299–7309, 2008

Atom transfer radical polymerization of N‐vinyl carbazole: Optimization to characterization

AbstractThe homopolymerization of N‐vinylcarbazole was performed with atom transfer radical polymerization (ATRP) with Cu(I)/Cu(II)/2,2′‐bipyridine (bpy) as the catalyst system at 90 °C in toluene. N‐2‐Bromoethyl carbazole was used as the initiator, and the optimized ratio of Cu(I) to Cu(II) was found to be 1/0.3. The resulting homopolymer, poly(N‐vinylcarbazole) (PVK), was formed after a monomer conversion of 76% in 20 h. The molecular weight as well as the polydispersity index (PDI) showed a linear relation with the conversion, which showed control over the polymerization. A semilogarithmic plot of the monomer conversion with time was linear, indicating the presence of constant active species throughout the polymerization. The initiator efficiency and the effect of the variation of the initiator concentration on the polymerization were studied. The effects of the addition of CuBr2, the variation of the catalyst concentration with respect to the initiator, and CuX (X = Br or Cl) on the kinetics of homopolymerization were determined. With Cu(0)/CuBr2/bpy as the catalyst, faster polymerization was observed. For a chain‐extension experiments, PVK (number‐average molecular weight = 1900; PDI = 1.24) was used as a macroinitiator for the ATRP of methyl methacrylate, and this resulted in the formation of a block copolymer that gave a monomodal curve in gel permeation chromatography. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1745–1757, 2006

Estimation of Seed Dispersal in an Old-Growth Population of Longleaf Pine (Pinus palustris) Using Maternity Exclusion Analysis

In this study, we used multilocus allozyme markers and maternity exclusion analysis to estimate dispersal distances in an old-growth population of a wind-dispersed conifer, Pinus palustris. Of 2,618 seeds analyzed, 11.3% did not have maternal parents within 75 m, 7.8% had a single possible maternal parent, and 80.9% had more than one possible maternal parent within 75 m. Using a variety of methods, a consensus dispersal curve was obtained and can be described as a broad mono-modal curve with peak dispersal at a distance of 35–60 m from the parent. Total gene flow beyond 75 m was calculated to be 54%, suggesting that a substantial percentage of gametes dispersed beyond 75 m. Results indicate that seeds of longleaf pine have the potential to disperse greater distances than previously reported, which may explain, in part, the low levels of genetic structure in this old-growth population.

The effect of orally administered melatonin on the seasonality of deer pelage exchange, antler development, LH, FSH, prolactin, testosterone, T3, T4, cortisol and alkaline phosphatase.

Five milligrams of melatonin (M) per day was administered orally to four male white-tailed deer on a schedule that mimicked first decreasing and then increasing lengths of natural photoperiod. The following seasonal phenotypic and hormonal responses were observed: Pelage exchange, antler mineralization, velvet shedding, and rutting behavior of experimental animals were advanced by 50-55 days. Prolactin (PRL) levels exhibited a bimodal curve with peaks in May and August, as compared to a monomodal curve of controls (peak in June). Peak FSH levels of M-fed deer were advanced 2 months as compared to controls (June vs August). LH concentrations of both groups reached maxima in July; however, in the experimental group, LH levels declined much faster than in controls and then rose again in October-November. Testosterone (T) concentrations of M-fed bucks were elevated 2 months ahead of controls. Melatonin treatment had no significant effect on seasonal variation of T3, or T4. No seasonal rhythm of cortisol was seen in either group and no detectable effect of M was evident. No statistical differences in levels of alkaline phosphatase were seen between groups, although concentrations in experimental bucks sharply dropped to basal levels two months ahead of controls.

Size distribution of atmospheric aerosols in seoul

Urban aerosol particle size distributions over the size range 0.01–1.0 μm have been determined by using an electrical aerosol analyzer at the Hanyang University in Seoul from May through to October 1984. The results indicate that the total average number distribution in the size range of 0.1–1.0 μm can be represented as the Junge distribution with dN/ d( log D p ) = 28.9 D p −3.1. The total average surface distribution is characterized by a monomodal curve with its maximum in the vicinity of 0.13 μm, while the maximum of the total average volume distribution appears to be shifted to a larger size than that of the surface distribution showing an almost flat line for D p 0.5 μm, which implies that a secondary maximum may exist for D p 1.0 μm. The time development of the number size distributions for the total size range shows the minimum number in the early morning before 4 a.m. followed by a rapid increase by the morning rush hour. This development in the 0.1–1.0 μm range is characterized by the maximum numbers in the morning and evening rush hours when dense traffic and a low mixing depth coexist with high relative humidity. The photochemical production of small particles in the 0.01–0.1 μm range is verified from monthly variation of number concentration and duration of sunshine. In general the monthly development of the surface and volume distributions shows the highest values to be in spring with the lowest in summer.

Studies on Fructification in the Peanut as Related to the Position on the Plant.

1) Both the total Weight and the average weight of seeds in the pulse were found heavier at the nodes nearer to the base of the plant and became lighter in accordance to the height of the position. The total seed weight for single node were often found heaviest at the third or fourth node ; the relation of seed weights to the order of nodes might be represented by a monomodal curve. 2) The increasing rate of the total weight or the average one of the seeds are shown in Fig. 1 and 2. Trans location of nutrients into seed grains seems to be faster at the lower nodes on the branch. 3) The grain of the first flower in a cluster became heavier than those of the second or third flower, though they bloomed on the same day.

The blooming and maturing of red bean as related to various sowing times

I observed the habitude of plooming and maturing of red bean in the various sowing times and contemplated the relation between the yield of climatic elements and the above habitude. The results obtained are as follows. (1), The number of flower has the tendency to decrease as the sowing time delays. The flowering-date distribution in the case of early or proper sowing time shows the bi- or tri- modal curve, and in the delayed sowing shows mono-modal curve. The blooming period in the early or delayed sowing is shortet than the period in the proper sowing. (2), The blooming of every flower on a plant bigins from the middle node to the upper and lower nodes. On the branch, the flower of basal node blooms earlier than the top one. (3), The each period from 50 % blooming to maturing needs about 30 days. (4), The maturing-date distribution have the same tendency as the flowering one. (5), The seed number per pod seems to easily controlled by the environment, and have the tendency to decrease as the sowing time delays. When the sowing time delays and the maturing time prolongs, the seed becomes bigger. (6), The yield (seed weight) decreased as the sowing time delays in spite of the exaggerated vegetative growth. (7), It seems that the favourable air temperature on blooming are higher than 30°C maximum, 20°C minimum, 26°C average and the additional temperature from sowing to blooming needs more than about 1000°C.