No abstract

Natural resins were frequently employed in the past as adhesives or as components of oleo-resinous media in paintings. The identification of vegetable resins is still an open problem. The aim of this paper is to analyse by GC-MS some vegetable resins frequently employed in paintings, such as Venice turpentine, dammar, copal, elemi, in order to identify their main components in samples both raw and aged. Some molecules are proposed as chemical markers to identify these natural resins. Two samples scraped off from XV and XVII century paintings were used to test the reliability of proposed method.

CRONO is a new portable and easy reconfigurable macro X-ray fluorescence scanner based on the energy dispersive X-ray fluorescence technique, which has been specifically designed for in-situ, fast, and non-invasive elemental mapping of polychrome surfaces. The main components are fully integrated into the detection head which includes an X-ray tube, a large area silicon drift detector, a microscope camera, two pointing lasers, a Helium gas purging set, and fast acquisition electronics. This very compact detection head is mounted on motorized stages (with a linear speed up to 45 mm/s) that allow the scanning of areas up to 450 × 600 mm 2 . Three collimators (0.5, 1, and 2-mm diameter) are software selectable to obtain different spot sizes on the sample. The typical measurement time for the full scanned area ranges from 1 h with the 2-mm collimator to about 9 h with the 0.5-mm collimator using a dwell time of 30 ms. Technical details and achievable performances of the instrument are presented and discussed along with an example of application which illustrates the value of the developed instrument in the investigation of paintings.

In this paper, we propose a new metaheuristic to solve the Risk constrained Cash-in-Transit Vehicle Routing Problem (rctvrp). The rctvrp is a variant of the well-known capacitated vehicle routing problem and models the problem of routing vehicles in the cash-in-transit sector. In the rctvrp, the risk associated with a robbery represents a critical aspect that is treated as a limiting factor instead of the vehicle capacity which is typical of capacitated vehicle routing problems. The risk of being robbed is assumed to be proportional both to the amount of cash being transported and the time/distance covered by the vehicle carrying the cash. The maximum vehicle exposure to risk limited by a certain risk threshold.A new metaheuristic, called aLNS (Ant colony heuristic with Large Neighbourhood Search), is described. The aLNS metaheuristic combines the ant colony heuristic for the travelling salesman problem and a large neighbourhood search heuristic within an iterated local search heuristic framework.A new library of rctvrp instances with known optimal solutions is proposed, and split in two sets named set O and set S respectively. The aLNS algorithm is extensively tested on small, medium and large benchmark instances and compared with all existing solution approaches for the rctvrp problem.

Smalt is a blue pigment used by many European artists in mural and easel paintings, mainly in the period from the XV to XVIII century. It is a potassium glass where cobalt is added to the glassy matrix to get the blue hue. The pigment deteriorates with age, changing its colour from an intense blue to a grey-yellowish hue, causing severe problems in the conservation of the paintings. In this study a set of specimens of smalt dispersed in linseed oil was prepared and artificially aged to simulate the progressive deterioration of the pigment in a painting on canvas. The artificially aged smalt specimens were compared with some samples of naturally aged smalt taken from a banner painted at the end of XV century by Luca Signorelli, the “Baptism of Jesus”. A multi-technique approach, including SEM-EDX, spectro-colorimetry, X-ray absorption spectroscopy and ab initio calculations, was used to understand the progressive discoloration and to reveal its correlation with changes occurring in the pigment structure