Chlorophyll degradation in heat-treated Chlorella pyrenoidosa. A flow cytometric study

The process of chlorophyll degradation of Chlorella pyrenoidosa was studied by flow cytometry using intrinsic chlorophyll fluorescence as the gauge. The small vegetative cells of a synchronous culture were subjected to a heat pre-treatment (46.5ºC for 1 h in the dark) and cultured again under continuous illumination thereafter. The cellular chlorophylls vanished within about 24 h after the heat pre-treatment in two distinguishable stages, which corresponded to the two major stages of the present model for chlorophyll degradation. It was found that, although both stages were light-dependent, they differed in several aspects. The first stage of degradation, in which the whole cell population uniformly converted its chlorophylls into pheopigments, started immediately after light-on during recultivation, and continued even after light-off for a long period (~60 h), indicating that all cells responded to light without delay, and the process continued once triggered. The second stage of degradation, in which cells opened their chlorophyll macrocycles and lost their green color, did not start until after about 8 h of illumination, and each individual cell actually entered this process at a somewhat different time (8–24 h). In addition, the conversion of each cell was fast, but the process in the population as a whole stopped whenever illumination was off. This indicates that the second stage proceeds in a random mode, and that light must be present during the conversion of each cell. It was also found that the process of pigment breakdown could be turned on by illumination as low as 4 mol m –2 s –1 , but was abolished by a period of dark treatment, suggesting that light played a triggering role, and the ‘signal’ for chlorophyll degradation set up by the heat pre-treatment was automatically canceled after a certain time without light triggering.

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Specific heat-temperature curves of some age-hardening alloys

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1938.0172 ◽

1938 ◽

Vol 168 (933) ◽

pp. 237-264 ◽

Cited By ~ 18

Keyword(s):

Low Temperatures ◽

Lattice Parameter ◽

Age Hardening ◽

Second Stage ◽

Large Numbers ◽

Heat Treated ◽

Or Groups ◽

Set Up ◽

Lower Temperature ◽

Two Stages

In a recent paper Gayler (1937) has dealt with the various theories of age hardening and has put forward the view that ageing takes place in two stages: in the first stage the solute atoms diffuse to planes about which precipitation proper will ultimately take place, and this gives rise to an increase in resistance to deformation and an increase in electrical resistivity without change in lattice parameter. The second stage follows the first and takes place nearly simultaneously. Some of the diffusing atoms will form molecules gradually form groups which will tend to produce a gradual decrease in resistivity and a diminution in the rate of hardening. When the molecular groups have grown to such an extent that the parent solid solution can no longer withstand the stresses set up, release of these stresses is caused by rejection of the groups, i. e. precipitation proper takes place. Once precipitation has set in them, according to Gayler's view, softening should begin. This theory tends to combine the "Knot" theory (Gayler and Preston 1932), which states that age-hardening occurs due to the formation of clusters or groups of atoms inside the parent lattice (the first stage, according to Gayler), and the precipitation theory (Merica and other 1919) which attributed hardening to the presence of large numbers of precipitated particles, probably ultramicroscopic in size, dispersed throughout the material. Naturally the formation of clusters or knots will occur at a lower temperature than precipitation, so that at low temperatures hardening will occur by the mechanism of the first stage. At high temperatures hardening may take place due to precipitation, the first stage being masked entirely. The question as to which of the tow processes is likely to be more effective in any particular alloy when heat-treated to give the maximum hardness obtainable in the hardening range is not specifically dealt with by Gayler, although it is stated that the experimental evidence available suggests that the second stage is, in general, more important. The work of Cohen (1936) on the silver-copper alloy containing 7∙5 % copper supports this contention, since his results show that hardening due to knot formation even at low temperatures (100-150°C) is very small indeed.

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UVA-LED Technology’s Treatment Efficiency and Cost in a Competitive Trial Applied to the Photo-Fenton Treatment of Landfill Leachate

Processes ◽

10.3390/pr9061026 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1026

Author(s):

Javier Tejera ◽

Antonio Gascó ◽

Daphne Hermosilla ◽

Víctor Alonso-Gomez ◽

Carlos Negro ◽

...

Keyword(s):

Landfill Leachate ◽

Mercury Vapor ◽

Cod Removal ◽

Treatment Efficiency ◽

Alternative Source ◽

Effluent Quality ◽

Radiation Sources ◽

Initial Ph ◽

Pre Treatment ◽

Set Up

The objective of this trial was to assess the application of UVA-LED technology as an alternative source of irradiation for photo-Fenton processes, aiming to reduce treatment costs and provide a feasible treatment for landfill leachate. An optimized combination of coagulation with ferric chloride followed by photo-Fenton treatment of landfill leachate was optimized. Three different radiation sources were tested, namely, two conventional high-pressure mercury-vapor immersion lamps (100 W and 450 W) and a custom-designed 8 W 365 nm UVA-LED lamp. The proposed treatment combination resulted in very efficient degradation of landfill leachate (COD removal = 90%). The coagulation pre-treatment removed about 70% of the COD and provided the necessary amount of iron for the subsequent photo-Fenton treatment, and it further favored this process by acidifying the solution to an optimum initial pH of 2.8. The 90% removal of color improved the penetration of radiation into the medium and by extension improved treatment efficiency. The faster the Fenton reactions were, as determined by the stoichiometric optimum set-up reaction condition of [H2O2]0/COD0 = 2.125, the better were the treatment results in terms of COD removal and biodegradability enhancement because the chances to scavenge oxidant agents were limited. The 100 W lamp was the least efficient one in terms of final effluent quality and operational cost figures. UVA-LED technology, assessed as the application of an 8 W 365 nm lamp, provided competitive results in terms of COD removal, biodegradability enhancement, and operational costs (35–55%) when compared to the performance of the 450 W conventional lamp.

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Fast Two-Stage Computation of an Index Policy for Multi-Armed Bandits with Setup Delays

Mathematics ◽

10.3390/math9010052 ◽

2020 ◽

Vol 9 (1) ◽

pp. 52

Author(s):

José Niño-Mora

Keyword(s):

Numerical Study ◽

Arithmetic Operation ◽

Bandit Problem ◽

Index Policy ◽

Two Stage ◽

Second Stage ◽

Whittle Index ◽

Set Up ◽

Computing Method ◽

Special Case

We consider the multi-armed bandit problem with penalties for switching that include setup delays and costs, extending the former results of the author for the special case with no switching delays. A priority index for projects with setup delays that characterizes, in part, optimal policies was introduced by Asawa and Teneketzis in 1996, yet without giving a means of computing it. We present a fast two-stage index computing method, which computes the continuation index (which applies when the project has been set up) in a first stage and certain extra quantities with cubic (arithmetic-operation) complexity in the number of project states and then computes the switching index (which applies when the project is not set up), in a second stage, with quadratic complexity. The approach is based on new methodological advances on restless bandit indexation, which are introduced and deployed herein, being motivated by the limitations of previous results, exploiting the fact that the aforementioned index is the Whittle index of the project in its restless reformulation. A numerical study demonstrates substantial runtime speed-ups of the new two-stage index algorithm versus a general one-stage Whittle index algorithm. The study further gives evidence that, in a multi-project setting, the index policy is consistently nearly optimal.

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Refining the prognostic significance of dna ploidy status in colorectal cancer: A prospective flow cytometric study

International Journal of Cancer ◽

10.1002/ijc.2910410208 ◽

1988 ◽

Vol 41 (2) ◽

pp. 206-210 ◽

Cited By ~ 32

Author(s):

D. J. Jones ◽

M. Moore ◽

P. F. Schofield

Keyword(s):

Colorectal Cancer ◽

Dna Ploidy ◽

Prognostic Significance ◽

Flow Cytometric ◽

Flow Cytometric Study ◽

Ploidy Status

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Prognostic factors in mucoepidermoid carcinomas of major salivary glands: A clinicopathologic and flow cytometric study

European Journal of Cancer Part B Oral Oncology ◽

10.1016/0964-1955(94)90034-5 ◽

1994 ◽

Vol 30 (5) ◽

pp. 329-334 ◽

Cited By ~ 26

Author(s):

M. John Hicks ◽

Adel K. El-Naggar ◽

Robert M. Byers ◽

Catherine M. Flaitz ◽

Mario A. Luna ◽

...

Keyword(s):

Prognostic Factors ◽

Salivary Glands ◽

Flow Cytometric ◽

Major Salivary Glands ◽

Flow Cytometric Study

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Peripheral primitive neuroectodermal tumour and extra-osseous Ewing's sarcoma; a histological, immunohistochemical and DNA flow cytometric study

Virchows Archiv ◽

10.1007/bf00199351 ◽

1995 ◽

Vol 425 (6) ◽

pp. 611-616 ◽

Cited By ~ 28

Author(s):

M. Brinkhuis ◽

L. C. D. Wijnaendts ◽

J. C. van der Linden ◽

J. P. A. Baak ◽

C. J. L. M. Meijer ◽

...

Keyword(s):

Ewing’S Sarcoma ◽

Ewing's Sarcoma ◽

Primitive Neuroectodermal Tumour ◽

Flow Cytometric ◽

Neuroectodermal Tumour ◽

Flow Cytometric Study

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Application of Tailored Heat Treated Blanks under Quasi Series Conditions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.344.383 ◽

2007 ◽

Vol 344 ◽

pp. 383-390 ◽

Cited By ~ 3

Author(s):

Marion Merklein ◽

Uwe Vogt

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Local Heat ◽

Strength Distribution ◽

Process Window ◽

Short Term ◽

Forming Process ◽

Heat Treated ◽

Set Up ◽

The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

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Correlation between germinal vesicle and oocyte development in the adult Japanese quail (Coturnix coturnix japonica). A cytochemical and autoradiographic study

Development ◽

10.1242/dev.29.1.145 ◽

1973 ◽

Vol 29 (1) ◽

pp. 145-157

Author(s):

Marc Callebaut

Keyword(s):

Japanese Quail ◽

Intraperitoneal Injection ◽

Developmental Stages ◽

Germinal Vesicle ◽

Autoradiographic Study ◽

Continuous Illumination ◽

Coturnix Coturnix ◽

Second Stage ◽

Body Complex ◽

Distinct Morphology

Continuity in the various developmental stages of the oocytes in the adult laying Japanese quail may be demonstrated with a method of whole stock labelling of their nuclei by successive applications of [3H]thymidine during their premeiotic period. Before they mature, the intraovarian oocytes of the adult Japanese quail go through three important successive stages. In each of these stages the chromosomes have a distinct morphology and cytochemical behaviour. During the first stage or prelampbrush chromosome stage, the chromosomes are Feulgen-positive or green after Unna, and on the autoradiographs show intense incorporation of [3H]uridine after injection of this RNA precursor into the animal. During the beginning of this period, which is of very variable duration, the oocyte seems to be in a state of structural stability. The most prominent feature found in the ooplasm of oocytes at this stage is the very large paranuclear Balbiani yolk-body complex, which can be found labelled after injection of [3H]thymidine into the animal. During the second stage or lampbrush chromosome stage, the Feulgen nuclear reaction in the chromosomes weakens or becomes negative and the paranuclear Balbiani yolk-body complex disappears. After Unna, the lampbrush chromosomes and their lateral loops are seen to be pyroninophilic. On the autoradiographs after intraperitoneal injection of [3H]uridine rapid and intense RNase-sensitive incorporation of this precursor over the chromosomes and nucleoplasm may be noted. During this stage there is thus both cytochemical and autoradiographic evidence for RNA synthesis in the rapidly enlarging germinal vesicle. During the third or postlampbrush stage activity in the germinal vesicle sharply decreases; the volume of the germinal vesicle no longer increases, the very contracted chromosomes are present in the form of Feulgenpositive vacuolized central spherules, and, after intraperitoneal injection of [3H]uridine into the adult laying quail, incorporation cannot be demonstrated in the chromosomes. By contrast, the fundamental part of the ooplasm derived from the cortex, at that moment shows both cytochemical and autoradiographic evidence of the presence and/or synthesis of nucleic acids. The postlampbrush stage is a characteristic feature of non-mature oocytes with a germinal disc and can only be found in regularly laying Japanese quails exposed to full daytime or continuous illumination.

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