Transcriptional Analysis of Lactobacillus brevis to N-Butanol and Ferulic Acid Stress Responses

The presence of anti-microbial phenolic compounds, such as the model compound ferulic acid, in biomass hydrolysates pose significant challenges to the widespread use of biomass in conjunction with whole cell biocatalysis or fermentation. Currently, these inhibitory compounds must be removed through additional downstream processing or sufficiently diluted to create environments suitable for most industrially important microbial strains. Simultaneously, product toxicity must also be overcome to allow for efficient production of next generation biofuels such as n-butanol, isopropanol, and others from these low cost feedstocks.This study explores the high ferulic acid and n-butanol tolerance in Lactobacillus brevis, a lactic acid bacterium often found in fermentation processes, by global transcriptional response analysis. The transcriptional profile of L. brevis reveals that the presence of ferulic acid triggers the expression of currently uncharacterized membrane proteins, possibly in an effort to counteract ferulic acid induced changes in membrane fluidity and ion leakage. In contrast to the ferulic acid stress response, n-butanol challenges to growing cultures primarily induce genes within the fatty acid synthesis pathway and reduced the proportion of 19:1 cyclopropane fatty acid within the L. brevis membrane. Both inhibitors also triggered generalized stress responses. Separate attempts to alter flux through the Escherichia coli fatty acid synthesis by overexpressing acetyl-CoA carboxylase subunits and deleting cyclopropane fatty acid synthase (cfa) both failed to improve n-butanol tolerance in E. coli, indicating that additional components of the stress response are required to confer n-butanol resistance.Several promising routes for understanding both ferulic acid and n-butanol tolerance have been identified from L. brevis gene expression data. These insights may be used to guide further engineering of model industrial organisms to better tolerate both classes of inhibitors to enable facile production of biofuels from lignocellulosic biomass

Luminescence properties of pHEMA-TiO2TiO_2 gels based hybrids materials

International audiencePhotoluminescence (PL) of photochromic pHEMA-TiO2 gels-based hybrids was studied by means of time- and energy-resolved spectroscopy at temperatures between 300 K and 10 K. The PL band at 485 nm is assigned to S0←T1 transition of methoxyphenol (organic molecule added to the commercial monomer hydroxyethyl methacrylate, HEMA and used as an inhibitor of spontaneous polymerisation) in the polymer environment, while the PL band at 600 nm is assigned to the self-trapped exciton onto octahedral TiO6 site of the inorganic component. The mechanisms of the excited states population are discussed. In particular it is shown that both singlet-triplet energy transfer in methoxyphenol and methoxyphenol–TiO2 charge transfer are strongly affected by the material composition and temperature. The hypothesis about the photoexcited holes annihilation with the trapped electrons is confirmed to be one of main mechanisms limiting the Ti3+ centres concentration

Construction and first tests of a PET-like detector for hadrontherapy beam ballistic control

International audienceWe present the first results obtained with a detector, called Large Area Pixelized Detector (LAPD), dedicated to the beam ballistic control in the context of hadrontherapy. The purpose is to control the ballistics of the beam delivered to the patient by in-beam and real time detection of secondary particles, emitted during its irradiation. These particles could be high energy photons (γ prompt), or charged particles like protons, or 511 keV γ from the annihilation of a positron issued from the β+ emitters induced in the patient tissues along the beam path. These methods require being able to detect with a huge efficiency, and with a minimum dead time, these secondary particles emitted when the beam hits the patient.The LAPD is similar to a conventional Positron Emission Tomography camera. The 511 keV γ are detected and the reconstructed line of responses allow to measure the β+ activity distribution. Nevertheless, when trying to use γ from positron annihilations for the ballistic control in hadrontherapy, the large γ prompt background should be taken into account and properly rejected.This detector is made of two half-rings of 120 channels each. Each channel consists of a 13*13*15 mm3 LYSO crystal glued to a PMT. The PMT signal is sent to an Analog Sampling Module (ASM board). This VME 6U board is based on the DRS4 chip technology (Switch Capacitor Array) from the Paul Sherrer Institute and was specially designed for the LAPD detector. This board receives up to 24 differential analog input signals, with maximum amplitude of 600 mV, digitized by 12 bits - 33 MHz ADC. The sampling rate varies between 1 and 5 GHz, for a maximum buffer size of 1024 samples.The first part of the talk is devoted to the description of the detector and its electronics. Then, we describe the various trigger strategy, and the on-going upgrade of the VME-based acquisition system to a μTCA-based technology. The selection of the coincident 511 keV γ is also discussed, and the reconstruction using an iterative MLEM algorithm is presented. In the last part of the talk, few results from an experiment with one third of the detector, using proton and carbon ion beams at the Heidelberg Ion-Beam Therapy Center in 2014, are also described, and the Coincidence Resolution Time and energy resolution are given. First reconstruction results, obtained with a phantom filled with a high intensity FDG source at the cancer research center of Clermont- Ferrand in 2015 are also shown.This detector is now characterized, and will be installed at the Lacassagne hadrontherapy center (Nice, France), on the 65 MeV line (Medicyc) in December 2015 first, and on the future 230 MeV line (S2C2 from IBA) in 2016. The capability of this detector and its associated electronics to measure the ballistic of the proton beam in real clinical conditions with a sufficient precision will be evaluated

Trigger optimization for in-beam PET dedicated to particle therapy range verification

International audiencePurpose: Proton and carbon ion therapies are a very attractive treatment modality thanks to their well-defined range in matter and specific depth dose characteristics. However, it is very hard to precisely predict the exact location of the depth dose steep fall-off in the patient. This is mainly due to inaccuracies and non-uniqueness in the conversion from the Hounsfield Unit into ion stopping power, anatomical changes, patient positioning and movement. Because of these uncertainties, in-vivo ion range verification would be a key issue which would allow improvement in the precision of such methods of treatment delivery

Alkoxysilane effect in hybrid material: A comparison of pHEMA-TiO2 and pMAPTMS-TiO2 nanoparticulate hybrids

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Construction and tests of an in-beam PET-like demonstrator for hadrontherapy beam ballistic control

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