نتایج جستجو برای: silica boron

تعداد نتایج: 55027  

Journal: :The Plant cell 2014
Mithu Chatterjee Zara Tabi Mary Galli Simon Malcomber Amy Buck Michael Muszynski Andrea Gallavotti

Although boron has a relatively low natural abundance, it is an essential plant micronutrient. Boron deficiencies cause major crop losses in several areas of the world, affecting reproduction and yield in diverse plant species. Despite the importance of boron in crop productivity, surprisingly little is known about its effects on developing reproductive organs. We isolated a maize (Zea mays) mu...

2004
B. S. Dear

Boron deficiency was first recorded in Australia in the 1930s in apple trees growing in Tasmania and New South Wales. Subsequently the deficiency was found in a wide range of pasture and crop plants. Crops with higher boron requirements such as lucerne, sunflowers, rapeseed, cauliflower and apples are most likely to respond to boron. Pine trees, which are commonly used in tree lots and as windb...

2017
Katie M. Cergol Peter Turner Mark J. Coster

The first examples of the directed, boron-mediated aldol reaction between different ketones are presented. Transformation of a variety of ketones to their corresponding boron enolates with Chx2BCl/Et3N, followed by reaction with acceptor ketones in diethyl ether, and oxidation of the resultant boron aldolate (H2O2, MeOH/pH 7 buffer), provided the aldol addition products. The reaction was most f...

2012
Chaitanya K. Narula Heinrich Nöth

The chemistry of boron cations was a field long neglected [2]. Meanwhile, many cations containing tetracoordinated boron have been reported [3] and their chemistry has been explored. In addition there exists scattered information relating to tri[4-8] and dicoordinated [9, 10] boron cations. Unlike carbenium ion chemistry their role in boron chemistry is not yet well understood. This situation, ...

2004
P. J. Vaughan P. J. Shouse J. E. Ayars

THERE is a restricted range of boron concentration in soil water that is beneficial to plants. At lower concentrations, plants exhibit boron deficiency, whereas at higher concentration, phytotoxicity occurs. The specific range of favorable response varies by species but has been characterized as 0.028 to 0.093 mmol L 1 for sensitive crops and 0.37 to 1.39 mmol L 1 for tolerant crops (Keren and ...

Journal: :Environmental toxicology and chemistry 2001
G Loewengart

From the large data set available on the toxicity of boron to aquatic organisms, the toxicity of boron to the early life stages of rainbow trout (Oncorhyncus mykiss) is the seminal issue relative to setting water quality criteria and effluent standards. Issues associated with the early life stage studies are the flat concentration-response curve, the low threshold of toxicity, and teratogenic e...

Introduction: Boron neutron capture therapy (BNCT) is a method of cancer treatment and potentially, two borono-L-phenylalanine (BPA) and sodium borocaptate (BSH) are used in BNCT as common boron carriers. Some previous studies have shown that the dose rate is directly related to boron concentration in the tissue. This study aimed to simulate the structure of boron carriers and brain tumor compo...

Journal: :Plant physiology 2000
C Dordas M J Chrispeels P H Brown

Boron is an essential micronutrient for plant growth and the boron content of plants differs greatly, but the mechanism(s) of its uptake into cells is not known. Boron is present in the soil solution as boric acid and it is in this form that it enters the roots. We determined the boron permeability coefficient of purified plasma membrane vesicles obtained from squash (Cucurbita pepo) roots and ...

2016
Laurentia Gales

25 Laurentia Gales 258 Șos.Fundeni, 2nd District, Bucharest, Romania e-mail: [email protected] Abstract. Boron neutron capture theory (BNCT) is a binary therapy applied in malignant tumours, resistant to other treatment methods, namely chemotherapy and radiotherapy. One of the main components is Bor-10, a stable isotope that can be inserted in the tumour cells by using specific transpor...

Journal: :Clinical chemistry 2001
J Laakso M Kulvik I Ruokonen J Vähätalo R Zilliacus M Färkkilä M Kallio

BACKGROUND Boron neutron-capture therapy (BNCT) is a drug-targeted binary radiotherapy for cancer. The (10)B capture of thermal neutrons induces secondary radiation within cells during irradiation. The most widely used boron carrier is 4-dihydroxyborylphenylalanine (BPA). The duration and timing of the irradiation is adjusted by monitoring (10)B concentrations in whole blood. METHODS We devel...

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