Comparing human and automatic thesaurus mapping approaches in the agricultural domain

Knowledge organization systems (KOS), like thesauri and other controlled vocabularies, are used to provide subject access to information systems across the web. Due to the heterogeneity of these systems, mapping between vocabularies becomes crucial for retrieving relevant information. However, mapping thesauri is a laborious task, and thus big efforts are being made to automate the mapping process. This paper examines two mapping approaches involving the agricultural thesaurus AGROVOC, one machine-created and one human created. We are addressing the basic question "What are the pros and cons of human and automatic mapping and how can they complement each other?" By pointing out the difficulties in specific cases or groups of cases and grouping the sample into simple and difficult types of mappings, we show the limitations of current automatic methods and come up with some basic recommendations on what approach to use when.Comment: 10 pages, Int'l Conf. on Dublin Core and Metadata Applications 200

Toward Environmentally Benign Electrophilic Chlorinations:From Chloroperoxidase to Bioinspired Isoporphyrins

Recent desires to develop environmentally benign procedures for electrophilic chlorinations have encouraged researchers to take inspiration from nature. In particular, the enzyme chloroperoxidase (CPO), which is capable of electrophilic chlorinations through the umpolung of chloride by oxidation with hydrogen peroxide (H2O2), has received lots of attention. CPO itself is unsuitable for industrial use because of its tendency to decompose in the presence of excess H2O2. Biomimetic complexes (CPO active-site mimics) were then developed and have been shown to successfully catalyze electrophilic chlorinations but are too synthetically demanding to be economically viable. Reported efforts at generating the putative active chlorinating agent of CPO (an iron hypochlorite species) via the umpolung of chloride and using simple meso-substituted iron porphyrins were unsuccessful. Instead, a meso-chloroisoporphyrin intermediate was formed, which was shown to be equally capable of performing electrophilic chlorinations. The current developments toward a potential method involving this novel intermediate for environmentally benign electrophilic chlorinations are discussed. Although this novel pathway no longer follows the mechanism of CPO, it was developed from efforts to replicate its function, showing the power that drawing inspiration from nature can have

The role of salicylic acid, L-ascorbic acid and oxalic acid in promoting the oxidation of alkenes with H(2)O(2) catalysed by [Mn(IV) (2)(O)(3)(tmtacn)(2)](2+)

The role played by the additives salicylic acid, L-ascorbic acid and oxalic acid in promoting the catalytic activity of [Mn(IV) (2)(O)(3)(tmtacn)(2)](PF(6))(2) {1(PF(6))(2), where tmtacn = N, N ', N ''-trimethyl-1,4,7-triazacyclononane} in the epoxidation and cis-dihydroxylation of alkenes with H(2)O(2) and in suppressing the catalysed decomposition of H2O2 is examined. Whereas aliphatic and aromatic carboxylic acids effect enhancement of the catalytic activity of 1 through the in situ formation dinuclear carboxylato bridged complexes of the type [ Mn(III) (2)(mu-O)(mu-RCO(2))(2)(tmtacn)(2)](2+), for L-ascorbic acid and oxalic acid notable differences in reactivity are observed. Although for L-ascorbic acid key differences in the spectroscopic properties of the reaction mixtures are observed compared with carboxylic acids, the involvement of carboxylic acids formed in situ is apparent. For oxalic acid the situation is more complex with two distinct catalyst systems in operation; the first, which engages in epoxidation only, is dominant until the oxalic acid additive is consumed completely at which point carboxylic acids formed in situ take on the role of additives to form a second distinct catalyst system, i.e. that which was observed for alkyl and aromatic carboxylic acids, which yield both cis-diol and epoxide products

Synthesis and characterisation of ruthenium complexes containing a pendent catechol ring

A series of [Ru(bipy)₂L]⁺ and [Ru(phen)₂L]⁺ complexes where L is 2-[5-(3,4-dimethoxyphenyl)-4H-1,2,4-triazol-3-yl]pyridine (HL1) and 4-(5-pyridin-2-yl-4H-1,2,4-triazol-3-yl)benzene-1,2-diol (HL2) are reported. The compounds obtained have been characterised using X-ray crystallography, NMR, UV/Vis and emission spectroscopies. Partial deuteriation is used to determine the nature of the emitting state and to simplify the NMR spectra. The acid-base properties of the compounds are also investigated. The electronic structures of [Ru(bipy)₂L1]⁺ and Ru(bipy)₂HL1]²⁺ are examined using ZINDO. Electro and spectroelectrochemical studies on [Ru(bipy)₂(L2)]⁺ suggest that proton transfer between the catechol and triazole moieties on L2 takes place upon oxidation of the L2 ligand

The role of carboxylato ligand dissociation in the oxidation of chrysin with H2O2 catalysed by [Mn-2 (III, IV)(mu-CH3COO)(mu-O)(2)(Me(4)dtne)](PF6)(2)

The aqueous and non-aqueous chemistry of the complex [Mn-2 (III,IV)(mu-CH3COO)(mu-O)(2)(Me(4)dtne)](PF6)(2) (where Me(4)dtne = 1,2-bis(4,7-dimethyl- 1,4,7-triazacyclonon-1-yl) ethane), which has been demonstrated as an exceptionally active catalyst in the bleaching of raw cotton and especially wood pulp at high pH (&gt;11), is explored by UV/vis absorption, Raman and EPR spectroscopies and cyclic voltammetry. The data indicate that dissociation of the mu-acetato bridge is essential to the catalyst activity and rationalises the effect of sequestrants such as DTPA on its performance.</p

Lewis versus Brønsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation

Lewis acid (LA) activation by coordination to metal oxido species has emerged as a new strategy in catalytic oxidations. Despite the many reports of enhancement of performance in oxidation catalysis, direct evidence for LA-catalyst interactions under catalytically relevant conditions is lacking. Here, we show, using the oxidation of alkenes with H2O2 and the catalyst [Mn2(μ-O)3(tmtacn)2](PF6)2 (1), that Lewis acids commonly used to enhance catalytic activity, e.g., Sc(OTf)3, in fact undergo hydrolysis with adventitious water to release a strong Brønsted acid. The formation of Brønsted acids in situ is demonstrated using a combination of resonance Raman, UV/vis absorption spectroscopy, cyclic voltammetry, isotope labeling, and DFT calculations. The involvement of Brønsted acids in LA enhanced systems shown here holds implications for the conclusions reached in regard to the relevance of direct LA-metal oxido interactions under catalytic conditions

Supplementary data for the article: Steen, J. D.; Stepanovic, S.; Parvizian, M.; De Boer, J. W.; Hage, R.; Chen, J.; Swart, M.; Gruden, M.; Browne, W. R. Lewis versus Brønsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation. Inorganic Chemistry 2019, 58 (21), 14924–14930. https://doi.org/10.1021/acs.inorgchem.9b02737

Supplementary material for: [https://doi.org/10.1021/acs.inorgchem.9b02737]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3691

Detection of Melanoma Metastases in Resected Human Lymph Nodes by Noninvasive Multispectral Photoacoustic Imaging

Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads to an increased survival in node-positive patients. However, frozen section analysis of the sentinel node is not reliable and definitive histopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging can evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared multispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the present study is to examine the potential of multispectral photoacoustic imaging to identify melanoma metastasis in human lymph nodes. Methods. Three metastatic and nine benign lymph nodes from eight melanoma patients were scanned ex vivo using a Vevo LAZR multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology as gold standard. Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to identify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The penetration depth of the photoacoustic signal was up to 2 cm. Conclusion. Multispectral three-dimensional photoacoustic imaging allowed for selective identification of melanoma metastases in human lymph nodes