scholarly journals CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM

1946 ◽  
Vol 29 (6) ◽  
pp. 419-427 ◽  
Author(s):  
Jack Myers ◽  
Keyword(s):  
Light Intensity ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Chlorophyll Concentration ◽  
Dry Weight ◽  
Chlorella Pyrenoidosa ◽  
Cell Number ◽  
Culture Conditions ◽  
Photosynthetic Unit ◽  
Incandescent Lamps

1. Chlorella pyrenoidosa has been grown in a continuous-culture apparatus under various light intensities provided by incandescent lamps, other conditions of culture being maintained constant. The harvested cells were analyzed for cell number, dry weight, nitrogen, and chlorophyll per unit cell volume. 2. Cell nitrogen and cell volume are parallel measures of cellular material over the range of light intensity studied. 3. The dry weight per cell volume increases slowly with light intensity, showing about a 20 per cent variation. 4. Chlorophyll concentration and cell number show a concomitant decrease with increasing light intensity, varying in such a way that there are always about the same number of chlorophyll molecules per cell. It is considered that this phenomenon has bearing on the interpretation of data which has led to the theory of the photosynthetic unit.

Effect of Certain Quinones, Diquat, and Diuron on Chlorella pyrenoidosa Chick. (Emerson strain)

Weed Science ◽  
1968 ◽  
Vol 16 (1) ◽  
pp. 69-73 ◽  
Author(s):  
G. Zweig ◽  
J. E. Hitt ◽  
R. McMahon
Keyword(s):  
Chlorophyll Content ◽  
Oxygen Evolution ◽  
Physiological Activity ◽  
Chlorophyll Concentration ◽  
Chlorella Pyrenoidosa ◽  
Inhibitory Effect ◽  
Cell Number ◽  
Drastic Decrease ◽  
Oxygen Evolving

The effect of 1,4-naphthoquinone, 1,4-benzoquinone, and several CI and NH2-substituted quinones has been studied on growth, chlorophyll concentration, and oxygen evolution in Chlorella pyrenoidosa Chick. (Emerson strain). Drastic decrease of the studied parameters usually was noted after 24 to 48 hr treatment at 3×10–5 M concentration. The effect of the quinones was compared with that of 6,7-dihydrodipyrido [l,2-a:2,l-c-]pyrazidinium salt (diquat) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron). Diuron inhibited oxygen evolution immediately after addition, but could be washed out and the effect was reversible. Diquat had no inhibitory effect on oxygen evolution and chlorophyll content but caused a slight decrease in cell number. Although some quinones have an almost immediate effect on the oxygen-evolving mechanism, it seems more likely that the overall effect of the quinones is on the total physiological activity of the algal cells. Oxygen evolution seems to affected earlier than chlorophyll destruction, and the observed long-term damage is irreversible. Most of the compounds studied could be classified as algicidal, with the exception of diuron, diquat, and 1,4-benzoquinone which may be considered to be algistatic.

scholarly journals Light Intensity Affects Growth, Photosynthetic Capability, and Total Flavonoid Accumulation of Anoectochilus Plants

HortScience ◽  
2010 ◽  
Vol 45 (6) ◽  
pp. 863-867 ◽  
Author(s):  
Zengqiang Ma ◽  
Shishang Li ◽  
Meijun Zhang ◽  
Shihao Jiang ◽  
Yulan Xiao
Keyword(s):  
Light Intensity ◽  
Chlorophyll Concentration ◽  
Dry Weight ◽  
Total Flavonoid ◽  
Stem Length ◽  
Photon Flux ◽  
Low Light ◽  
Four Levels ◽  
Anoectochilus Formosanus ◽  
Flavonoid Accumulation

Anoectochilus formosanus, a medicinal plant used to treat hypertension, lung disease, and liver disease, was grown to maximize biomass and secondary metabolite production in a controlled environment under four levels of photosynthetic photon flux (PPF), namely, 10, 30, 60, or 90 μmol·m−2·s−1, that is L10, L30, L60, and L90 treatments, respectively. On Day 45, all growth values were greatest for the L30 plants. Dry weight was lowest for the L10 plants. Leaf area, stem length, and fresh weight were lowest for the L90 plants. The chlorophyll concentration was highest in the L10 treatment and decreased with increasing PPF. Electron transport ratios of leaves were highest in the L30 treatment and lowest in the L90 for the second leaf (counted down from the apex) and in the L10 for the third leaf. An increase in light intensity from 10 to 60 μmol·m−2·s−1 increased the superoxide dismutase activity and was associated with an increase in the total flavonoid concentration. The total flavonoid concentration (mg·g−1 DW) was greatest in the L60 and lowest in the L90. However, the total flavonoid content (mg/plant) was highest in the L30 plants as a result of great biomass. The results indicated that A. formosanus is a typical shade plant suitable to grow under low light intensity at PPF of 30 to 50 μmol·m−2·s−1 for both growth and production of total flavonoid. A light intensity of 90 μmol·m−2·s−1 induced stress on plant growth and reduced photosynthetic capability and the flavonoid accumulation.

Cadmium toxicity on synchronous populations of Chlorella ellipsoidea

1980 ◽  
Vol 58 (16) ◽  
pp. 1780-1788 ◽  
Author(s):  
H. Lue-Kim ◽  
P. C. Wozniak ◽  
R. A. Fletcher
Keyword(s):  
Cell Division ◽  
Toxic Effect ◽  
Cadmium Toxicity ◽  
Chlorophyll Concentration ◽  
Membrane Integrity ◽  
Dry Weight ◽  
Cell Number ◽  
Dark Phase ◽  
Chlorella Ellipsoidea ◽  
Synchronous Cultures

The primary phycotoxic effects of various concentrations (5–50 μM) of cadmium sulfate (CdSO4) on synchronous cultures of Chlorella ellipsoidea were determined during a 14-h light and a 10-h dark incubation cycle. At a concentration of 5 μM CdSO4 there was a slight stimulation in cell number, chlorophyll level, and dry weight whereas at higher concentrations (10–40 μM) a linear decrease in these parameters was evident. At even higher concentrations, 50 μM and above, cytolysis occurred. Inhibition of chlorophyll concentration and dry weight was greater the longer the cultures were exposed to cadmium. Cell division was completely arrested when toxic levels of cadmium were administered any time throughout the duration of the light phase. However, the severity of toxicity of cadmium, when applied during the dark phase, increased with the length of time of exposure. Cadmium toxicity also resulted in disturbances in cell division. Treated cells became larger than control cells. Unequal sporulation, microcolony and incipient microcolony formation, swelling, increased photolucence, and disruption of mitochondria occurred following treatment of cultures with toxic levels of cadmium. A further toxic effect of cadmium might relate to an increase in membrane permeability. Treatment of cultures with increasing concentrations of cadmium resulted in intracellular cadmium exceeding extracellular cadmium levels. The primary toxic effect of cadmium on synchronous cultures of C. ellipsoidea was attributed to a lack of cell division probably related to insufficient synthesis of chlorophyll and dry weight components as well as to a disruption of membrane integrity.

The interrelation of susceptibility to breakdown, cell size, and nitrogen and phosphorus levels in Jonathan apple fruits

1965 ◽  
Vol 16 (4) ◽  
pp. 617 ◽  
Author(s):  
D Martin ◽  
NS Stenhouse ◽  
TL Lewis ◽  
J Cerny
Keyword(s):  
Nitrogen Content ◽  
Cell Volume ◽  
Negative Relationship ◽  
Dry Weight ◽  
Cell Number ◽  
Nitrogen And Phosphorus ◽  
Individual Tree ◽  
Phosphorus And Potassium ◽  
Low Incidence ◽  
Nitrogen Phosphorus

A block of Jonathan apple trees were treated for 4 years as individual tree plots with nil, nitrogen, nitrogen + phosphorus, and nitrogen + potassium applied as sprays during two periods, either in spring before bud differentiation or after bud differentiation in mid January. The treatments had no effect on the levels of phosphorus or potassium in the fruit. Spring applications had no significant effect on the nitrogen content, but summer applications a marked one, though there was no evidence of a cumulative build-up or any effect on cell number per fruit. These increases in nitrogen content were accompanied by small increases in breakdown level, but only when an inherent seasonal susceptibility existed. Only a diminishing proportion of the additional nitrogen was incorporated into the protein fraction, and the preclimacteric respiration rate was not affected significantly by the increase in protein. Except for percentage dry matter, there was a wide variation in the values between trees of the variables, which permitted a multiple regression analysis. The regression of breakdown and cell volume was positive and highly significant in all years. Except for the year of very low incidence, there was a significant positive relationship between breakdown and nitrogen level, and a consistent negative relationship between breakdown and phosphorus level which was significant in the years of high breakdown incidence. No relationship could be shown between breakdown and potassium. Similar results were obtained by using a percentage fresh weight or percentage dry weight basis for the nitrogen, phosphorus, and potassium contents, or by using actual values or a log (x + 1) transformation for the variables, though there were some advantages in using the latter. The results suggest an important physiological interaction between breakdown and cell volume, nitrogen, and phosphorus.

Cell Size and Pretransplant Nutritional Conditioning Influences Early Vine Growth and Yield of Transplanted Watermelon

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 594e-594
Author(s):  
Charles J. Graham
Keyword(s):  
Cell Volume ◽  
Significant Influence ◽  
Field Performance ◽  
Dry Weight ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Average Weight ◽  
Shoot Dry Weight ◽  
Solids Concentration ◽  
Soluble Solids Concentration

Research is needed to better understand the influence of cell volume and fertility on watermelon transplant size and field performance in order to determine the most economic production practices. `Jubilee' watermelon transplants were grown using a 4 x 4 factorial experimental design consisting of 4 cell volumes (30.7, 65.5, 147.5, and 349.6 cm3) and 4 fertility rates (0, 1/4, 1/2, and full-strength Hoagland's solution). Transplant shoot dry weight significantly increased as cell volume and fertility increased. Increasing cell volume linearly increased watermelon number/ha and tons/ha for early and total harvest in 1995. The average weight per watermelon significantly increased for early-harvested fruit but not for total harvest as cell volume increased in 1995. Soluble solids concentration linearly increased with increasing cell volume for early and total harvests in 1995. Cell volume had no significant influence on the harvest parameters measured in 1997. In 1995, increasing fertility linearly increased watermelon number/ha and tons/ha for early harvests. Increasing fertility increased the soluble solids concentration linearly for early-harvested watermelons in 1997 but not in 1995. Fertility rate had no significant influence on any of the other harvest parameters measured in 1995 and 1997. The growing conditions and disease pressure in 1997 reduced melons/ha, yield, and soluble solids content when compared to 1995 values. The half-strength Hoagland's solution produced the greatest number of watermelons/ha, tons/ha, and the highest soluble solids concentration in 1995 and 1997. Pretransplant nutritional conditioning had no significant effect on total `Jubilee' watermelon production in Louisiana for 1995 and 1997.

scholarly journals Negative thermal expansion in YbMn2Ge2 induced by the dual effect of magnetism and valence transition

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yongqiang Qiao ◽  
Yuzhu Song ◽  
Andrea Sanson ◽  
Longlong Fan ◽  
Qiang Sun ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Intermetallic Compound ◽  
Cell Volume ◽  
Valence State ◽  
Unit Cell Volume ◽  
Negative Thermal Expansion ◽  
Combined Effect ◽  
Dual Effect ◽  
Valence Transition ◽  
Magnetovolume Effect

AbstractNegative thermal expansion (NTE) is an intriguing property, which is generally triggered by a single NTE mechanism. In this work, an enhanced NTE (αv = −32.9 × 10−6 K−1, ΔT = 175 K) is achieved in YbMn2Ge2 intermetallic compound to be caused by a dual effect of magnetism and valence transition. In YbMn2Ge2, the Mn sublattice that forms the antiferromagnetic structure induces the magnetovolume effect, which contributes to the NTE below the Néel temperature (525 K). Concomitantly, the valence state of Yb increases from 2.40 to 2.82 in the temperature range of 300–700 K, which simultaneously causes the contraction of the unit cell volume due to smaller volume of Yb3+ than that of Yb2+. As a result, such combined effect gives rise to an enhanced NTE. The present study not only sheds light on the peculiar NTE mechanism of YbMn2Ge2, but also indicates the dual effect as a possible promising method to produce enhanced NTE materials.

scholarly journals Variability in Macro- and Micronutrients of 15 Commercially Available Microalgae Powders

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 310
Author(s):  
Fabian Sandgruber ◽  
Annekathrin Gielsdorf ◽  
Anja C. Baur ◽  
Benjamin Schenz ◽  
Sandra Marie Müller ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Dunaliella Salina ◽  
Haematococcus Pluvialis ◽  
Saturated Fatty Acids ◽  
Dry Weight ◽  
Chlorella Pyrenoidosa ◽  
Essential Amino Acids ◽  
Arthrospira Platensis ◽  
Omega 3 ◽  
Tetraselmis Chuii

The nutrient composition of 15 commercially available microalgae powders of Arthrospira platensis, Chlorella pyrenoidosa and vulgaris, Dunaliella salina, Haematococcus pluvialis, Tetraselmis chuii, and Aphanizomenon flos-aquae was analyzed. The Dunaliella salina powders were characterized by a high content of carbohydrates, saturated fatty acids (SFAs), omega-6-polyunsaturated fatty acids (n6-PUFAs), heavy metals, and α-tocopherol, whereas the protein amounts, essential amino acids (EAAs), omega-3-PUFAs (n3-PUFAs), vitamins, and minerals were low. In the powder of Haematococcus pluvialis, ten times higher amounts of carotenoids compared to all other analyzed powders were determined, yet it was low in vitamins D and E, protein, and EAAs, and the n6/n3-PUFAs ratio was comparably high. Vitamin B12, quantified as cobalamin, was below 0.02 mg/100 g dry weight (d.w.) in all studied powders. Based on our analysis, microalgae such as Aphanizomenon and Chlorella may contribute to an adequate intake of critical nutrients such as protein with a high content of EAAs, dietary fibers, n3-PUFAs, Ca, Fe, Mg, and Zn, as well as vitamin D and E. Yet, the nutritional value of Aphanizomenon flos-aquae was slightly decreased by high contents of SFAs. The present data show that microalgae are rich in valuable nutrients, but the macro- and micronutrient profiles differ strongly between and within species.

scholarly journals Allanite at high temperature: effect of REE on the thermal behaviour of epidote-group minerals

2021 ◽  
Vol 48 (9) ◽  
Author(s):  
G. Diego Gatta ◽  
Francesco Pagliaro ◽  
Paolo Lotti ◽  
Alessandro Guastoni ◽  
Laura Cañadillas-Delgado ◽  
...  
Keyword(s):  
Cell Volume ◽  
Thermal Behaviour ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Atomic Scale ◽  
Elastic Behaviour ◽  
Positive Trend ◽  
Cell Parameters ◽  
Thermal Anisotropy ◽  
Different Temperatures

AbstractThe thermal behaviour of a natural allanite-(Ce) has been investigated up to 1073 K (at room pressure) by means of in situ synchrotron powder X-ray diffraction and single-crystal neutron diffraction. Allanite preserves its crystallinity up to 1073 K. However, up to 700 K, the thermal behaviour along the three principal crystallographic axes, of the monoclinic β angle and of the unit-cell volume follow monotonically increasing trends, which are almost linear. At T > 700–800 K, a drastic change takes place: an inversion of the trend is observed along the a and b axes (more pronounced along b) and for the monoclinic β angle; in contrast, an anomalous increase of the expansion is observed along the c axis, which controls the positive trend experienced by the unit-cell volume at T > 700–800 K. Data collected back to room T, after the HT experiments, show unit-cell parameters significantly different with respect to those previously measured at 293 K: allanite responds with an ideal elastic behaviour up to 700 K, and at T > 700–800 K its behaviour deviates from the elasticity field. The thermo-elastic behaviour up to 700 K was modelled with a modified Holland–Powell EoS; for the unit-cell volume, we obtained the following parameters: VT0 = 467.33(6) Å3 and αT0(V) = 2.8(3) × 10–5 K−1. The thermal anisotropy, derived on the basis of the axial expansion along the three main crystallographic directions, is the following: αT0(a):αT0(b):αT0(c) = 1.08:1:1.36. The T-induced mechanisms, at the atomic scale, are described on the basis of the neutron structure refinements at different temperatures. Evidence of dehydroxylation effect at T ≥ 848 K are reported. A comparison between the thermal behaviour of allanite, epidote and clinozoisite is carried out.

scholarly journals Study of Structural, Magnetic, and Mossbauer Properties of Dy2Fe16Ga1−xNbx (0.0 ≤ x ≤ 1.0) Prepared via Arc Melting Process

2021 ◽  
Vol 7 (3) ◽  
pp. 42
Author(s):  
Jiba N. Dahal ◽  
Kalangala Sikkanther Syed Ali ◽  
Sanjay R. Mishra
Keyword(s):  
Isomer Shift ◽  
Cell Volume ◽  
Intermetallic Compounds ◽  
Unit Cell Volume ◽  
Rietveld Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Nb Content

Intermetallic compounds of Dy2Fe16Ga1−xNbx (x = 0.0 to 1.00) were synthesized by arc melting. Samples were investigated for structural, magnetic, and hyperfine properties using X-ray diffraction, vibration sample magnetometer, and Mossbauer spectrometer, respectively. The Rietveld analysis of room temperature X-ray diffraction data shows that all the samples were crystallized in Th2Fe17 structure. The unit cell volume of alloys increased linearly with an increase in Nb content. The maximum Curie temperature Tc ~523 K for x = 0.6 sample is higher than Tc = 153 K of Dy2Fe17. The saturation magnetization decreased linearly with increasing Nb content from 61.57 emu/g for x = 0.0 to 42.46 emu/g for x = 1.0. The Mössbauer spectra and Rietveld analysis showed a small amount of DyFe3 and NbFe2 secondary phases at x = 1.0. The hyperfine field of Dy2Fe16Ga1−xNbx decreased while the isomer shift values increased with the Nb content. The observed increase in isomer shift may have resulted from the decrease in s electron density due to the unit cell volume expansion. The substantial increase in Tc of thus prepared intermetallic compounds is expected to have implications in magnets used for high-temperature applications.

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