There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

Contamination of soils by heavy metals is of widespread occurrence as a result of human, agricultural and industrial activities. Among heavy metals, lead is a potential pollutant that readily accumulates in soils and sediments. Although lead is not an essential element for plants, it gets easily absorbed and accumulated in different plant parts. Uptake of Pb in plants is regulated by pH, particle size and cation exchange capacity of the soils as well as by root exudation and other physico-chemical parameters. Excess Pb causes a number of toxicity symptoms in plants e.g. stunted growth, chlorosis and blackening of root system. Pb inhibits photosynthesis, upsets mineral nutrition and water balance, changes hormonal status and affects membrane structure and permeability. This review addresses various morphological, physiological and biochemical effects of Pb toxicity and also strategies adopted by plants for Pb-detoxification and developing tolerance to Pb. Mechanisms of Pb-detoxification include sequestration of Pb in the vacuole, phytochelatin synthesis and binding to glutathione and aminoacids etc. Pb tolerance is associated with the capacity of plants to restrict Pb to the cell walls, synthesis of osmolytes and activation of antioxidant defense system. Remediation of soils contaminated with Pb using phytoremediation and rhizofiltration technologies appear to have great potential for cleaning of Pb-contaminated soils.

/pdf/lead-toxicity-in-plants-3nclmzsfwp.pdf

Lead toxicity in plants

Copper is an essential metal for normal plant growth and development, although it is also potentially toxic. Copper participates in numerous physiological processes and is an essential cofactor for many metalloproteins, however, problems arise when excess copper is present in cells. Excess copper inhibits plant growth and impairs important cellular processes (i.e., photosynthetic electron transport). Since copper is both an essential cofactor and a toxic element, involving a complex network of metal trafficking pathways, different strategies have evolved in plants to appropriately regulate its homeostasis as a function of the environmental copper level. Such strategies must prevent accumulation of the metal in the freely reactive form (metal detoxification pathways) and ensure proper delivery of this element to target metalloproteins. The mechanisms involved in the acquisition of this essential micronutrient have not been clearly defined although a number of genes have recently been identified which encode potential copper transporters. This review gives a briefly overview of the current understanding of the more important features concerning copper toxicity and tolerance in plants, and brings information of recent findings on copper trafficking including copper detoxification factors, copper transporters and copper chaperones.

Copper in plants

Plants for the future

In this study, a series of twenty-two ring-substituted naphthalene-1-carboxanilides were prepared and characterized. Primary in vitro screening of the synthesized carboxanilides was performed against Mycobacterium avium subsp. paratuberculosis. N-(2-Methoxyphenyl)naphthalene-1-carboxamide, N-(3-methoxy-phenyl)naphthalene-1-carboxamide, N-(3-methylphenyl)naphthalene-1-carboxamide, N-(4-methylphenyl)naphthalene-1-carboxamide and N-(3-fluorophenyl)naphthalene-1-carboxamide showed against M. avium subsp. paratuberculosis two-fold higher activity than rifampicin and three-fold higher activity than ciprofloxacin. The most effective antimycobacterial compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. The testing of biological activity of the compounds was completed with the study of photosynthetic electron transport (PET) inhibition in isolated spinach (Spinacia oleracea L.) chloroplasts. The PET-inhibiting activity expressed by IC50 value of the most active compound N-[4-(trifluoromethyl)phenyl]naphthalene-1-carboxamide was 59 μmol/L. The structure-activity relationships are discussed.

/pdf/preparation-and-biological-properties-of-ring-substituted-iwwtes8nrj.pdf

Preparation and Biological Properties of Ring-Substituted Naphthalene-1-Carboxanilides

A set of N,N'-diarylalkanediamides was synthesized. The compounds were tested for their antimycobacterial and antialgal activity. The antimycobacterial activity of N,N'-diarylalkanediamides depends on the lipophilicity of the respective acid. Antimycobacterially active substances were found only in the series of N,N'-diarylethanediamides and N,N'-diarylbutanediamides. Other compounds (derivatives of pentane-, hexane-, octane- and nonanediamide) were inactive against various strains of mycobacteria. The compounds inhibited growth and chlorophyll production in Chlorella vulgaris. Their relatively low antialgal activity is probably connected with their lowered aqueous solubility, and hence by a restricted passage of the inhibitor through the hydrophilic regions of thylakoid membranes.

https://www.mdpi.com/1420-3049/5/5/714/pdf

Synthesis of N,N’-Diarylalkanediamides and Their Antimycobacterial and Antialgal Activity

The inhibitory effect of 14 aqua(aryloxyacetato) copper(II) complexes on oxygen evolution rate in spinach chloroplasts has been investigated. The in­ hibitory effect of these effectors on photosynthesi s was confirmed by Hill reaction as well as by EPR and fluorescence spectroscopies. The results of the EPR study showed that the sites of action of the studied effectors are Z+ and Y+ interme­ diates at the donor side of the photosystem (PS) 2. The EPR study also showed that another site of action is the oxygen evolving complex, namely its manganese cluster. The above suggestions were supported by the results of the fluorescence study as well. Based on the restoring of the photosynthetic electron transport to 2,6-dichlorophenol-indophenol in chloroplasts inhibited by the studied Cu(II) com­ plexes using sym-diphenylcarbazide it can be assumed that the own core of PS2 (P680) and a part of the electron transport chain - at least up to plastoquinone - remain intact.

/pdf/effects-of-cu-ii-complexes-on-photosynthesis-in-spinach-4nytdbts4y.pdf

Katarina Kralova

Papers

Plants for the future

Preparation and Biological Properties of Ring-Substituted Naphthalene-1-Carboxanilides

Synthesis of N,N’-Diarylalkanediamides and Their Antimycobacterial and Antialgal Activity

Effects of Cu(II) complexes on photosynthesis in spinach chloroplasts. Aqua(aryloxyacetato)copper(II) complexes.

Antimycobacterial N-alkoxyphenylhydroxynaphthalenecarboxamides affecting photosystem II.