The prevention of spoilage by Alicyclobacillus acidoterrestris is a current challenge for fruit juice and beverage industries worldwide due to the bacterium's acidothermophilic growth capability, ...heat resistance, and spoilage potential. This study examined the effect of storage temperature on A. acidoterrestris growth in hot-filled orange juice. The evolution of the A. acidoterrestris population was monitored under six different storage conditions after pasteurization (at 92°C for 10 s), maintenance at 85°C for 150 s, and cooling with water spray to 35°C in about 30 min and using two inoculum levels: <10¹ and 10¹ spores/ml. Final cooling and storage conditions were as follows: treatment 1, 30°C for the bottle cold point and storage at 35°C; treatment 2, 30°C for 48 h and storage at 35°C; treatment 3, 25°C for the bottle cold point and storage at 35°C; treatment 4, 25°C for 48 h and storage at 35°C; treatment 5, storage at 20°C (control); and treatment 6, filling and storage at 25°C. It was found that only in treatment 5 did the population remain inhibited during the 6 months of orange juice shelf life. By examining treatments 1 to 4, it was observed that A. acidoterrestris predicted growth parameters were significantly influenced (P < 0.05) either by inoculum level or cooling and storage conditions. The time required to reach a 10⁴ CFU/ml population of A. acidoterrestris was considered to be an adequate parameter to indicate orange juice spoilage by A. acidoterrestris. Therefore, hot-filled orange juice should be stored at or below 20°C to avoid spoilage by this microorganism. This procedure can be considered a safe and inexpensive alternative to other treatments proposed earlier.
Surface plasmon resonance (SPR) is a powerful technique for studying biomolecular interactions mainly due to its sensitivity and real-time and label free advantages. While SPR signals are usually ...positive, only a few studies have reported sensorgrams with negative signals. The aim of the present work is to investigate and to explain the observation of negative SPR signals with the hypothesis that it reflects major changes in ligand conformation resulting from target binding. We demonstrated that these negative unconventional signals were due to the negative complex (ligand/analyte) refractive index increment (RII) deviation from the sum of the RII of the individual entities which counterbalanced the theoretical increase of the signal triggered by the target recognition and the ligand folding. We also found that the conformation change of biomolecules can induce a negative or a positive complex RII deviation depending on its sequence and immobilization mode.
A rising global attention to the environmental impact of anthropogenic activities pushes towards a continuous reduction of such impact and a control, through monitoring techniques, of the main ...sources of pollution. The transport sector is involved, as all other field of anthropogenic activities in the efforts towards a drastic abatement of emissions. Shipping activities generate greenhouse effect gases (GHGs), affecting the environment on a global scale, and other pollutants harmful for human health and the ecosystem on a local scale. These latter aspects are particularly relevant in ports where berths are close to densely inhabited areas. Many efforts have been and will be spent to predict and quantify these emissions with the aim of controlling them but direct measurements aimed at the identification and quantification of particularly polluting substances are to be considered a key point to achieve an effective control of emissions. In the context of ports, as in any transportation infrastructure, an identification of polluting vehicles and a quantification in an objective way of their emissions is crucial to implement any control activity of the polluting emissions. The development of optical remote sensing techniques appears to be particularly promising. This work provides a state of the art of the main techniques based on optical sensors (LIDAR, LIDAR DIAL, DOAS, camera UV) possibly applied in the maritime sector, highlighting advantages and potentialities. Results of a preliminary measurement campaign are reported to show the first encouraging feedback for the feasibility of the application.
Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been ...applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.
Lidar measurements were performed in the framework of the EARLINET project during the last eruptions (July–August 2001 and November 2002) of the Etna volcano. Both aerosol backscattering and ...extinction coefficients show the presence of remarkable aerosol layers in central and especially in southern Europe during the Etna eruptions periods. The aerosol layer altitudes ranged from 1 to 6
km. Back-trajectory, lidar ratio and backscatter related Angstrom coefficient analyses show that most of the aerosol layers originated from the Etna eruption and were made of sulfates and small absorbing volcanic ash. Thanks to the EARLINET network, the space and temporal distributions of volcanic aerosol have been studied over continental scale.
The new developed elastic lidar system utilizes two identical elastic lidars, in counter-look configuration, to measure aerosol backscattering and extinction coefficients without any hypotheses. ...Compared to elastic-Raman lidar and high spectral resolution lidar, the proposed counter-look elastic lidar can use low power eyesafe laser and all available wavelengths. With this prototype lidar system, urban aerosol optical properties and their spatial distribution have been directly measured, including backscatter coefficient, extinction coefficient and lidar ratio. The preliminary results show that the low cost and eye-safe counter-look configured elastic lidar system can be used to measure the aerosol optical properties distribution and give the hint of aerosol type.
In order to carry out 4-D (space and time) analysis of the atmospheric aerosol distribution and to make a characterization of their properties and time evolution, a transportable multi-wavelength, ...Elastic/Raman scanning lidar system with angular scanning capability has been realized. The system uses a diode pumped Nd:YAG laser source, specifically designed for this device, and a receiving systems able to detect elastic signals at 355, 532 and 1064 nm and Raman signals at 386, 407 and 607 nm. It also allows to perform aerosol depolarization measurements at both 355nm and 532nm. A first measurement campaign has been carried out in Dunhuang, North-West of China, in the region of the Gobi desert with the aims to study and characterize desert dust at source. Optical properties of aerosol layers developing in the atmosphere have been analyzed and lidar data are discussed in terms of profiles of aerosol backscatter coefficient at 355nm, 532nm, aerosol extinction coefficient at 355nm, aerosol depolarization ratio at 355nm and 532nm and water vapor mixing ratio. Depolarization ratio measured simultaneously at two wavelengths allowed also to study its dependence on the wavelength.
In the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx;
http://charmex.lsce.ipsl.fr/
) initiative, a field campaign took place in the western Mediterranean Basin between 10 June ...and 5 July 2013 within the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project. The scientific objectives of ADRIMED are the characterization of the most common 'Mediterranean aerosols' and their direct radiative forcing (column closure and regional scale). During 15-24 June a multi-intrusion dust event took place over the western and central Mediterranean Basin. Extra measurements were carried out by some EARLINET/ACTRIS (European Aerosol Research Lidar Network /Aerosols, Clouds, and Trace gases Research InfraStructure Network,
http://www.actris.net/
) lidar stations in Spain and Italy, in particular on 22 June in support to the flight over southern Italy of the Falcon 20 aircraft involved in the campaign. This article describes the physical and optical properties of dust observed at the different lidar stations in terms of dust plume centre of mass, optical depth, lidar ratio, and particle depolarization ratio. To link the differences found in the origin of dust plumes, the results are discussed on the basis of back-trajectories and air- and space-borne lidars. This work puts forward the collaboration between a European research infrastructure (ACTRIS) and an international project (ChArMEx) on topics of interest for both parties, and more generally for the atmospheric community.
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