Sustainable manufacturing: evaluation and modeling of environmental impacts in additive manufacturing

Cleaner production and sustainability are of crucial importance in the field of manufacturing processes where great amounts of energy and materials are being consumed. Nowadays, additive manufacturing technologies such as direct additive laser manufacturing allow us to manufacture functional products with high added value. Insofar as environmental considerations become an important issue in our society, as well as legislation regarding environment become prominent (Normalization ISO 14 044), the environmental impact of those processes have to be evaluated in order to make easier its acceptance in the industrial world. Some studies have been conducted on electric consumption of machine tools (standby consumption, in process consumption, etc.) but only a few studies take into account the whole existing environmental flows (material, fluids, electricity). This paper presents a new methodology where all flows consumed (material, fluids, electricity) are considered in the environmental impact assessment. This method coupled a global view required in a sustainable approach and an accurate evaluation of flow consumption in the machine. The methodology developed is based on a predictive model of flow consumption defined from the manufacturing path and CAD model of the part which will be produce. In order to get an accurate model of the process, each feature of the machine is modeled. The goal of this work is to integrate this model into the design loop for additive manufacturing parts.     

Chiral Phosphoric Acid‐Catalyzed Enantioselective Aza‐Friedel–Crafts Alkylation of Indoles with γ‐Hydroxy‐γ‐lactams

An enantioselective aza‐Friedel–Crafts reaction of indoles with γ‐hydroxy‐γ‐lactams using a chiral phosphoric acid catalyst is reported. The approach described herein provides an efficient access to 5‐indolylpyrrolidinones in good to quantitative yields and excellent enantioselectivities (up to >99% ee). The results suggest that the reaction may proceed via N‐acyliminium intermediates associated with the chiral phosphoric acid anion.     

汽巴精化PVC行业用新型添加剂

PVC是最重要的热塑性聚合物之一,每年的产量和加工量接近2500万t。PVC的应用范围广,能和多种聚合物共混改进自身的物理机械性能。酚类产品,特别是受阻酚广泛用于PVC行业。新近开发的高效光稳定剂和其他功能性添加剂(抗菌、抗静电、防雾和荧光增白剂等)增强了PVC制品的品质,因此强化了PVC应用在市场中的地位。1受阻酚抗氧剂1.1PVC聚合中的链终止剂和抗氧剂理想的链终止剂必须能完全终止聚合反应,猝灭任何催化剂残留(自由基) ,以防止在生产中的过度聚合。从而,减少了停机清理的时间,提高了生产率。IRGANOX1141是两种受阻酚的协效复…     

Determination of pre-impact occupant postures and analysis of consequences on injury outcome--part II: biomechanical study

This paper considers pre-impact vehicle maneuvers and analyzes the resulting driver motion from their comfort seating position. Part I of this work consisted of analyzing the driver behavior during a simulated crash in a car driving simulator. The configuration of the virtual accident led to an unavoidable frontal crash with a truck. The typical response to this type of emergency event was to brace rearward into the seat and to straighten the arms against the steering wheel, or, to swerve to attempt to avoid the impacting vehicle. In a turn crossover maneuvers, the forearm is directly positioned on the airbag module at time of crash. This position represents a potential injurious situation and is investigated in this Part II.Static airbag-deployment tests were realized in collaboration with Zodiac using conventional airbag (sewn cushion, pyrotechnical system and open event) and a Hybrid III 50th Male Dummy seated with the left arm positioned in the path of the deploying airbag. These experiments were numerically reproduced with Madymo^® and the ellipsoid Hybrid III dummy model. The dummy arm interaction with airbag was correlated with experiments. Then, a numerical simulation of a frontal collision at 56 km/h was realized. The results of the computational runs put forward injurious situations when the driver's arm was in front of the steering wheel. Indeed, in this case, the arm could hit the head under airbag deployment and induced serious neck bending and violent head launching.To mitigate head and neck trauma in this out-of-position situation, an airbag prototype (bonded cushion, two pure helium cold gas generators allowing mono- or multi-stage inflating, patented silicone membrane) was proposed by Zodiac. The results of static airbag-deployment tests with conventional and prototype airbags showed a significant reduction of the maximum linear head acceleration and neck bending with airbag prototype when a dual stage inflating was ignited, due to a reduced ‘flinging’ of the arm.     

Toughening of epoxy matrices with reduced single-walled carbon nanotubes

Reduced single-walled carbon nanotubes (r-SWCNT) are shown to react readily at room temperature under inert atmosphere conditions with epoxide moieties, such as those in triglycidyl p-amino phenol (TGAP), to produce a soft covalently bonded interface around the SWCNT. The soft interface is compatible with the SWCNT-free cross-linked cured matrix and acts as a toughener for the composite. Incorporation of 0.2 wt % r-SWCNT enhances the ultimate tensile strength, toughness and fracture toughness by 32, 118, and 40%, respectively, without change in modulus. A toughening rate (dK(IC)/dwt(f)) of 200 MPa m(0.5) is obtained. The toughening mechanism is elucidated through dynamic mechanical analyses, Raman spectroscopy and imaging, and stress-strain curve analyses. The method is scalable and applicable to epoxy resins and systems used commercially.     

Internal microdosimetry of inhaled radon progeny in bronchial airways: advantages and limitations

The objective of the present study was to identify advantages and limitations of the application of microdosimetric concepts for inhaled radon progeny activities in the lungs. The methods employed for this analysis were a recently developed Monte-Carlo microdosimetry code for the calculation of energy deposition in bronchial target cells and the Probability Per Unit Track Length (PPUTL) model, which relates these microdosimetric parameters to cellular radiation effects. The major advantages of internal microdosimetry of radon progeny in bronchial airways are: (i) quantitative characterisation of non-uniform dose distributions and identification of target sites with enhanced carcinogenic potential, (ii) quantification of low doses of alpha particles by the number of cells hit and the dose received by those cells, (iii) illustration of the random variations of cellular doses by specific energy distributions and (iv) establishment of a direct link to cellular radiobiological effects. At present, a major limitation of microdosimetry is the extrapolation of the response of individual cells to the resulting tissue response, which is still not fully explored.     

Fabrication of functional nano-patterned surfaces by a combination of plasma processes and electron-beam lithography

This work presents a method for the fabrication of well defined chemically active nano-patterned surfaces. Electron-beam lithography has been combined with plasma-based processes in order to create sub-micron carboxylic functional areas over a non-bio-adhesive matrix. Characterization of the patterned surface by several surface analysis techniques reveals that this patterning technique is compatible with the plasma polymerization process in order to fabricate chemically active features with lateral size down to 300?nm. Moreover, experiments with a model protein (bovine serum albumin) on the patterned surfaces show preferential adhesion on the active region indicating the ability of this method for the design of biosensing platforms.