A Study of the Materials of Pontormo's “Portrait of Alessandro de' Medici”

2004 ◽  
Vol 852 ◽  
Author(s):  
Ken Sutherland ◽  
Beth A. Price ◽  
Irma Passeri ◽  
Mark Tucker

ABSTRACTIn studies of the materials of old master paintings, the characterization of thin and degraded layers often presents unusual challenges for routinely used methods of analysis. This paper discusses analyses performed as part of a study of the materials and techniques of Pontormo's “Portrait of Alessandro de’ Medici” (1534–5) carried out during a recent cleaning and restoration of the painting. Pontormo built up the portrait using a complex sequence of preparation, drawing and paint layers, the analysis of which was complicated further in some areas by the presence of degraded materials on the paint surface. The materials used for the various stages of preparation and painting were characterized by gas chromatography/mass spectrometry (GCMS), Fourier transform infrared microspectroscopy (FTIR) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The focus of this paper will be the particular approaches taken to the characterization of the preparation layers and degraded surface materials.

2017 ◽  
Vol 296 ◽  
pp. 86-94
Author(s):  
Robert Bachliński ◽  
◽  
Małgorzata Galarda ◽  

The article presents a case involving an appearance of an atypical 3,4-methylenedioxymethamphetamine (MDMA) in the form of nitrate on the illicit drug market. This compound can be identified only by using such analytical methods as capillary electrophoresis (CE) or scanning electron microscopy (SEM), which are not routinely applied to forensic analyses of this type of substances. Therefore, particular caution should be exercised whenever a gas chromatography-mass spectrometry (GC-MS) method unambiguously identifies a substance, yet infrared spectroscopy fails to confirm this result.


Holzforschung ◽  
2018 ◽  
Vol 72 (11) ◽  
pp. 951-960 ◽  
Author(s):  
Raziyeh Ghahremani ◽  
John A. Staser

AbstractLignin has been submitted to electrochemical oxidation in the presence of nickel (Ni), cobalt (Co) and Ni-Co bimetallic electrocatalysts, which were prepared by a simple electrochemical deposition process. The composition and morphology of the catalyst were studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA). The effects of the three electrocatalysts on the electrochemical oxidation of lignin were observed by cyclic voltammetry and chronoamperometry. The degradation products were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The rate of electrochemical oxidation of lignin is higher with Ni-Co bimetallic electrocatalyst with higher Co contents and the main products obtained were vanillin, apocynin and 3-methylbenzaldehyde.


2019 ◽  
Vol 12 (2) ◽  
pp. 229-239
Author(s):  
Usep Suhendar ◽  
Sogandi Sogandi

AbstrakKaries gigi adalah penyakit yang umum dialami oleh masyarakat yang terjadi karena buruknya kebersihan mulut. Kebiasaan masyarakat yang kurang menjaga kebersihan mulut mengakibatkan terbentuknya plak. Plak pada gigi terbentuk karena aktivitas dari berbagai macam mikroorganisme di mulut. Mikroorganisme yang diketahui terlibat dalam pembentukan karies gigi adalah Streptococcus mutans. Salah satu bahan alternatif sebagai antibakteri adalah daun cengkeh. Penelitian ini bertujuan untuk mengidentifikasi senyawa bioaktif daun cengkeh dan mengetahui mekanisme aksinya dalam menghambat pertumbuhan Streptococcus mutans. Daun cengkeh (Syzygium aromaticum) yang digunakan dalam penelitian ini dimaserasi menggunakan metanol 96%. Pengujian aktivitas antibakteri dilakukan dengan metode difusi agar, senyawa bioaktif diidentifikasi menggunakan gas chromatography mass spectrometry dan perubahan membran sel bakteri diamati dengan scanning electron microscopy. Hasil penelitian menunjukkan ekstrak metanol daun cengkeh memiliki aktivitas penghambatan terhadap pertumbuhan bakteri Streptococcus mutans dengan zona hambat sebesar ±32 mm serta nilai konsentrasi hambat minimum (KHM) 20% ekstrak. Mekanisme aksi penghambatan ekstrak daun cengkeh terhadap pertumbuhan bakteri diduga dengan membuat lubang pada membran sel bakteri. Hasil penelitian ini juga menunjukkan bahwa daun cengkeh memiliki kandungan senyawa bioaktif 3-allyl-6-methoxyphenol-eugenol, caryophyllene 1,4,7,-cycloundecatriene, 1,5,9,9-tetramethyl, phenol, 2-methoxy-4-(2-propenyl), dan eugenol acetate yang dapat menjadi kandidat penghasil senyawa aktif untuk mengatasi karies gigi.Abstract Dental caries is a common disease experienced by people who do not maintain oral hygiene. Habits of not maintain oral hygiene result in the formation of plaque. The microorganism known to be involved in the formation of dental caries is Streptococcus mutans. Plants that have antibacterial properties, such as clove (Syzygium aromaticum) leaf, can be an alternative for carrying this problem. This study aims to identify the bioactive compounds of clove leaves and to determine the mechanism of its action in inhibiting the growth of Streptococcus mutans. Clove leaves were macerated using 96% methanol for the extraction. Antibacterial activity was examined by agar diffusion method, bioactive compounds were identified using gas chromatography mass spectrometry, and bacterial cell membrane changes were observed by an image captured using scanning electron microscopy. The results showed that the methanol extract of clove leaf had inhibitory activity on Streptococcus mutans growth, with inhibitory zones of ±32 mm and the minimum inhibitory concentration (MIC) of 20% extract. It was suspected that the mechanism of inhibitory action is by making pores in the bacterial cell membrane. The results also showed that the clove leaves contain bioactive compounds of 3-allyl-6-methoxyphenol-eugenol, caryophyllene, 1,4,7, -cycloundecatriene, 1,5,9,9-tetramethyl, phenol, 2 -methoxy-4- (2-propenyl), and eugenol acetate which can be candidates for producing active compounds to overcome dental caries.


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