On the influence of gamma prime upon machining of advanced nickel based superalloy

Whilst gamma prime (γ′) phase is the strengthening phase in Ni-based superalloys its influence on machining has been seldom investigated. This paper reports for the first time on the effect of γ′ upon machining of Ni-based superalloys when cutting with parameters yielding different cutting temperature intervals which lead to strengthening/softening effects on the workpiece (sub)surface. In-depth XRD, SEM/FIB, EBSD analysis and unique micro-pillar testing in the workpiece superficial layers indicated that with the increase of γ′ fraction the grain plastic deformation significantly decreased, while specific cutting energy can switch from low to high values influenced by the real cutting temperature.     

Performance of 60 GHz Virtual Cellular Networks Using Multiple Receiving Antennas

During the past years, research covering propagation, channelcharacterization and wireless systems performance have yield asubstantial knowledge of the 60 GHz channel. The unlicensed 60 GHzfrequency band presents many attractive properties for wirelesscommunications. The environments in which the 60 GHzinfrastructure are to be designed are typically propagation- andcoverage-limited. This paper describes the important factors thatmust be taken into account when designing a wireless local areanetwork (WLAN) architecture operating in this frequency band.Therefore, we motivate the reasons of using distributedtransmitting antennas and multiple receiving antennas (MRA) inorder to mitigate the poor Direction of Arrival (DoA) diversityand to exploit the spatial diversity at the receiver. Such asystem can be considered as a multiple input multiple output(MIMO) system. We investigate the advantages of combining aVirtual Cellular Network (VCN) (using single frequency network anddistributed antennas) and MRA for the downlink. Several ways tocombine the signals with different levels of complexity arepresented. In the most complex case using Singular ValueDecomposition (SVD), it is possible to add coherently thecontribution of each antenna in a virtual cell while retaining thepath diversity inherent to the VCN infrastructure. The schemesyield several advantages: symbol diversity is improved, pathdiversity is still present, antenna gain using multiplebeamformers is increased and the multipath can be reduced. Theconcept is applicable to most types of single frequency networksbut it is especially well appropriate for the 60 GHz VCN/WLANusing orthogonal frequency division multiplexing (OFDM).Simulations give a realistic performance for QPSK, 8-PSK, and16-QAM baseband modulations with a 256-subcarrier OFDM using arate 1/2–convolutional code for a 2 ×2 VCN system.Results show a E_b/N₀ improvement of up to 6.2 dB usingthesingular value decomposition method with 16-QAM compared to thesingle input single output (SISO) coded reference.     

Nebulized Gadolinium‐Based Nanoparticles: A Theranostic Approach for Lung Tumor Imaging and Radiosensitization

Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium‐based ultra‐small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo‐time magnetic resonance imaging (UTE‐MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non‐invasively using fluorescence tomography or UTE‐MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization.     

Fate of N-nitrosodimethylamine, trihalomethane and haloacetic acid precursors in tertiary treatment including biofiltration

The presence of disinfection by-products (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and N-nitrosamines in water is of great concern due to their adverse effects on human health. In this work, the removal of N-nitrosodimethylamine (NDMA), total THM and five HAA precursors from secondary effluent by biological activated carbon (BAC) is investigated at full and pilot scale. In the pilot plant two filter media, sand and granular activated carbon, are tested. In addition, we evaluate the influence of ozonation prior to BAC filtration on its performance. Among the bulk of NDMA precursors, the fate of four pharmaceuticals containing a dimethylamino moiety in the chemical structure are individually investigated. Both NDMA formation potential and each of the studied pharmaceuticals are dramatically reduced by the BAC even in the absence of main ozonation prior to the filtration. The low removal of NDMA precursors at the sand filtration in comparison to the removal of NDMA precursors at the BAC suggests that adsorption may play an important role on the removal of NDMA precursors by BAC. Contrary, the precursors for THM and HAA formation are reduced in both sand filtration and BAC indicating that the precursors for the formation of these DBPs are to some extent biodegradable.     

Meaningful electronic signatures based on an automatic indexing method

Legal information certification and secured storage combined with documents electronic signature are of great interest when digital documents security and conservation are in concern. Therefore, these new and evolving technologies offer powerful abilities, such as identification, authentication and certification. The latter contribute to increase the global security of legal digital archives conservation and access. However, currently used cryptographic and hash coding concepts cannot intrinsically enclose cognitive information about both the signer and the signed content. Indeed, an evolution of these technologies may be necessary to achieve full text researches within hundreds or thousands of electronically signed documents. This article aims at describing a possible model along with associated processes to create and make use of these new electronic signatures called “meaningful electronic signatures” as opposed to traditional electronic signatures based on bit per bit computation.     

乙炔羰基化合成丙烯酸甲酯的研究

以乙炔、一氧化碳和甲醇为原料,卤化镍为主催化剂,羰基化合成丙烯酸甲酯,考察其在不同的反应温度、反应初始压力、原料配比、反应时间和催化剂用量下对反应结果的影响,确定最优的工艺条件。实验表明：以甲醇为溶剂,在185℃左右和5．2～5．5MPa的条件下,n（甲醇）：n（乙炔）：n（CO）=5．5～6．2：1：1,催化剂用量0．85wt％～0．9wt％,反应4～5h,丙烯酸甲醣的收率（相对乙炔）达到90％以上。     

Low dose powdered activated carbon addition at high sludge retention times to reduce fouling in membrane bioreactors

The addition of a low concentration of PAC (0.5 g L⁻¹ of sludge, i.e. a dose of 4 mg L⁻¹ of wastewater), in combination with a relatively long SRT (50 days), to improve membrane filtration performance was investigated in two pilot-scale MBRs treating real municipal wastewater. Continuous filterability tests at high flux showed the possibility to run for 18 h at 72 L m⁻² h⁻¹ and 180 h at 50 L m⁻² h⁻¹, while significant fouling occurred without PAC. In addition, measurements of the critical flux showed an increase of 10% for this strategy. Low dosage and high retention time makes it feasible and cost effective. Further advantages with regard to permeate quality and possible micropollutants removal are currently under investigation.     

Effect of Co,Pd and Pt ultra-thin films on the Ni-silicide formation: investigating the sandwich configuration

The effect of Co, Pd and Pt ultrathin films on the kinetics of the formation of Ni-silicide by reactive diffusion is investigated. 50 nm Ni/1 nm X/ 50 nm Ni (X?=?Co, Pd, Pt) deposited on Si(100) substrates are studied using in-situ and ex-situ measurements by X-ray diffraction (XRD). The presence of Co, Pd or Pt thin films in between the Ni layers delays the formation of the metal rich phase compared to the pure Ni/Si system and thus these films act as diffusion barriers. A simultaneous silicide formation (δ-Ni₂Si and NiSi phases) different from the classic sequential formation is found during the consumption of the top Ni layer for which Ni has to diffuse through the barrier. A model for the simultaneous growth in the presence of a barrier is developed, and simulation of the kinetics measured by XRD is used to determine the permeability of the different barriers. Atom probe tomography (APT) of the Ni/Pd/Ni system shows that the Pd layer is located between the Ni top layer and δ-Ni₂Si during the silicide growth, in accordance with a silicide formation controlled by Ni diffusion through the Pd layer. The effect of the barrier on the silicide formation and properties is discussed.