The forest biorefinery and its implementation in the pulp and paper industry: Energy overview

Incorporating a biorefinery unit to an operating Kraft pulping process has significant technological, economic and social advantages over the construction of a grassroot biorefinery. Also, the conversion of a Kraft mill from total pulp making to complete biorefinery can be done in a stepwise fashion and so give a company that envisages such transformation the opportunity to master the new technologies, evaluate options and develop an appropriate business plan. In all cases however, the road to conversion presents serious challenges. As components of the wood such as lignin or hemicelluloses are withdrawn from the Kraft pulp line, the heat production capacity from the recovery boiler where they are currently burnt is diminished. At the same time the operation of the added biorefinery unit increases the steam demand. In order to avoid fossil fuel dependency, the total site must be highly integrated and optimized. The application of an intensive and innovative energy optimization methodology to actual case studies has shown that the green, low GHG emissions biorefinery is feasible. The economics can be attractive for a site combining specialty wood pulp and bio-product, biomass gasification, power cogeneration and heat upgrading by optimally positioned and designed absorption heat cycles. The methodology has been applied to biorefining technologies for lignin and hemicelluloses extraction and valorisation, both technologies being coupled with gasification of wood residue.     

Diffuse and point sources of silica in the Seine River watershed

Dissolved silica (DSi) is believed to enter aquatic ecosystems primarily through diffuse sources by weathering. Point sources have generally been considered negligible, although recent reports of DSi inputs from domestic and industrial sources suggest otherwise. In addition, particulate amorphous silica (ASi) inputs from terrestrial ecosystems during soil erosion and in vegetation can dissolve and also be a significant source of DSi. We quantify here both point and diffuse sources of DSi and particulate ASi to the Seine River watershed. The total per capita point source inputs of Si (DSi + ASi) were found to be 1.0 and 0.8 g Si inhabitant(-1) d(-1) in raw and treated waters of the Achères wastewater treatment plant, in agreement with calculations based on average food intake and silica-containing washing products consumption. A mass balance of Si inputs and outputs for the Seine drainage network was established for wet and dry hydrological conditions (2001 and 2003, respectively). Diffuse sources of Si are of 1775 kg Si km(-2) y(-1) in wet conditions and 762 kg Si km(-2) y(-1) in dry conditions, with the proportion of ASi around 6%. Point sources of Si from urban discharge can contribute to more than 8% of the total Si inputs at the basin scale in hydrologically dry years. An in-stream retention of 6% of total inputs in dry conditions and 12% in wet conditions is inferred from the budget.     

Characterization and Modeling of Precipitation Kinetics in a Fe-Si-Ti Alloy

In this article, we present a systematic study of precipitation kinetics in a Fe-Si-Ti alloy in the temperature range 723?K to 853?K (450?°C to 580?°C), combining complementary tools (transmission electron microscopy (TEM), atom probe tomography (APT), and small-angle neutron scattering (SANS)). We show that the Heusler phase Fe₂SiTi dominates the precipitation process in the investigated time and temperature range, regardless of the details of the initial temperature history. A numerical model based on the evolution of precipitate size classes gives very good agreement with the experimental results, and its application to different alloy compositions provides directions for future alloy optimization.     

Contribution of encapsulation on the biodisponibility of retinol

To show the benefits of retinol encapsulation in cosmetic industry, we compared the diffusion of two different retinol preparations through skin:oil-in-water (o/w) emulsions of retinol, also called 'free retinol', and suspension of Cylasphere including retinol, also called 'encapsulated retinol'. Two methods were used: Franz cell elucidated retinol release and storage in a hairless mouse skin according to time for the two types of preparations. The dosage of retinol by high performance liquid chromatography (HPLC) showed that encapsulated retinol was maintained into the skin for a longer time than free retinol. Raman microspectrometry measurements established a spectral image of the skin and determined the localization of retinol. Maps were collected according to time. They detailed the shifts of free and encapsulated retinol in the epidermis of a human biopsy. Spheres were smaller than droplets and they moved two times faster at this level of the skin.     

Dendrimers or Nanoparticles as Supports for the Design of Efficient and Recoverable Organocatalysts?

The Jørgensen–Hayashi catalyst [(S)‐α,α‐diphenylprolinol trimethylsilyl ether] was grafted onto the surface of two different supports: phosphorus dendrimers (generations 1 to 3) and magnetic, polymer‐coated cobalt/carbon (Co/C) nanobeads. These new supported catalysts displayed high activities and selectivities in the Michael additions of a wide range of aldehydes to different nitroolefins. Moreover, the dendrimer of the third generation displayed excellent recycling abilities since it could be recovered and reused in 7 consecutive runs without loss of activity.     

The process dynamics of filler retention in paper using a CPAM/bentonite retention aid system

In an effort to develop robust control strategies for the wet‐end of papermaking, an experimental program was carried out to model the dynamic behaviour of the filler retention in paper using a Fourdrinier pilot paper machine and a cationic poly(acrylamide)/bentonite retention aid system. A dynamic simulation model of the pilot paper machine was developed from first‐principles. To describe the wet‐end chemistry effect, the first‐pass retention was included in the model as a new independent variable. The important factors affecting the dynamics of the wet‐end are first‐pass retention and the parameters related to the white water circulation.     

A physical explanation of the gas flow diode effect

Gas flow properties in channels with slightly varying cross section have a dependency on the direction of channel perfusion when the gas is in the slip and transitional flow regimes. In the past, it was observed that the flow rate in converging direction is higher compared to the case where the channel diverges alongside. This gas flow diode effect does neither exist in the continuum regime nor in the free molecular regime, and it has its maximum at the same level of gaseous rarefaction as the well-known Knudsen minimum. However, no comprehensive study on the physics of this diode effect is carried out yet. In order to overcome this knowledge gap, the current paper proceeds our previous works by an appropriate experimental study. Here we can show that the diode effect crucially depends on the proportion of inclined walls to the overall channel inner surface. Also the inclination of the wall itself determines the strength of the diode effect meaning that the diodicity increases with the opening angle. Furthermore, we found indication that the diodicity also depends on the molar mass and the internal structure of the impinging gas molecules. Finally, we propose an explanation of the diode effect that is mainly based on the tangential reflection process of gas molecules colliding with the inclined walls of a tapered channel.