The so-called internally channeled tube (ICT) is an innovative heat exchanger design proposed in our recent publications based on a channels-in-tube principle. A general, three-dimensional numerical ...model was suggested to describe fluid dynamics and heat transfer in the ICT. This model has already been validated for turbulent flow. The current paper presents an experimental investigation of the ICT and the model validation under laminar flow conditions. The experimental set-up and measurement procedure are given in detail and the maldistribution issue is addressed. The deviation between simulated and measured values is below 11% for the pressure drop and below 8% for the wall and bulk temperatures. Furthermore, the ICT performance was evaluated using performance evaluation criterion (PEC) including both heat transfer rate and pressure drop. Enhanced heat transfer in the ICT surpasses the associated pressure drop increase, yielding a PEC greater than one.
Ballasted aggregation, a process using the addition of a ballasting agent to improve the settling performance of flocs, appears particularly appropriate for the treatment of humic rich waters that ...leads to low-density aggregates. In that context, using an aquagenic humic acid coagulated by ferric chloride in the presence of pozzolana particles as ballasting agent, we show that the origin of improved floc settling in ballasted aggregation is not simply related to an increased specific weight of flocs, but also to a significant restructuring of flocs to a more compact structure induced by the added particles. The floc restructuring is evidenced from the increased lag time before measurable floc growth in the presence of the ballasting agent, the higher fractal dimension of flocs above the micron scale range after incorporation of the particles into the aggregates, and a much smaller sediment volume after settling. A simple model of floc compaction based on the turbulent viscous effects that act on an elastic floc, is described.
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•Ballast particles induce a significant floc compaction during ballasted aggregation.•Floc restructuring is revealed by an increased lag time before measurable floc growth.•The fractal dimension of flocs increases above the micron scale range.•Floc compaction is modelled from the turbulent viscous effects on an elastic floc.
Attempts at removal of drinking water biofilms rely on various preventive and curative strategies such as nutrient reduction in drinking water, disinfection or water flushing, which have demonstrated ...limited efficiency. The main reason for these failures is the cohesiveness of the biofilm driven by the physico-chemical properties of its exopolymeric matrix (EPS). Effective cleaning procedures should break up the matrix and/or change the elastic properties of bacterial biofilms. The aim of this study was to evaluate the change in the cohesive strength of two-month-old drinking water biofilms under increasing hydrodynamic shear stress τw (from ∼0.2 to ∼10 Pa) and shock chlorination (applied concentration at T0: 10 mg Cl2/L; 60 min contact time). Biofilm erosion (cell loss per unit surface area) and cohesiveness (changes in the detachment shear stress and cluster volumes measured by atomic force microscopy (AFM)) were studied.
When rapidly increasing the hydrodynamic constraint, biofilm removal was found to be dependent on a dual process of erosion and coalescence of the biofilm clusters. Indeed, 56% of the biofilm cells were removed with, concomitantly, a decrease in the number of the 50–300 μm3 clusters and an increase in the number of the smaller (i.e., <50 μm3) and larger (i.e., >600 μm3) ones. Moreover, AFM evidenced the strengthening of the biofilm structure along with the doubling of the number of contact points, NC, per cluster volume unit following the hydrodynamic disturbance. This suggests that the compactness of the biofilm exopolymers increases with hydrodynamic stress.
Shock chlorination removed cells (−75%) from the biofilm while reducing the volume of biofilm clusters. Oxidation stress resulted in a decrease in the cohesive strength profile of the remaining drinking water biofilms linked to a reduction in the number of contact points within the biofilm network structure in particular for the largest biofilm cluster volumes (>200 μm3). Changes in the cohesive strength of drinking water biofilms subsequent to cleaning/disinfection operations call into question the effectiveness of cleaning-in-place procedures. The combined alternating use of oxidation and shear stress sequences needs to be investigated as it could be an important adjunct to improving biofilm removal/reduction procedures.
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•Drinking water biofilm cohesion relates to 106 contact points/μm3 within EPS matrix.•Increase in hydrodynamic shear stress determines erosion and collapsing of biofilm.•Chlorination reduces biofilm density, cluster volume and EPS contact points.
Aim: To produce and analyze mupirocin nanomicelle (MP-NM) in insulin-based gel. Procedures: MP-NM was prepared using solvent evaporation with Tween 80 as a surfactant. HPMC polymer prepared gel. ...MP-NM was characterized by globular diameter, polydispersity index (PDI), pH, entrapment efficiency (EE), and transmission electron microscopy (TEM). NM MP release was studied in vitro. Results: The revolutionary MP-NM in insulin-based gel dissolves MP completely without precipitation due to its unique physical and chemical properties. MP had 8.64 ± 0.2 nm globular diameter, high EE (98.85 ± 0.01%), and normal homogeneous dispersion (PDI, 0.143 ± 0.003) in NM. MP's formula showed rapid first-order kinetics release. Conclusion: To our knowledge, this is the first MP-NM nano-drug delivery system employing insulin-based gel. It has promising pre-clinical and clinical uses.
The present study was aimed at designing and optimizing a rotating disk reactor simulating high hydrodynamic shear rates (γ), which are representative of cooling circuits. The characteristics of the ...hydrodynamic conditions in the reactor and the complex approach used to engineer it are described. A 60 l tank was filled with freshwater containing free-living amoebae (FLA) and bacteria. Adhesion of the bacteria and formation of a biofilm on the stainless steel coupons were observed. FLA were able to establish in these biofilms under γ as high as 85,000 s
−1
. Several physical mechanisms (convection, diffusion, sedimentation) could explain the accumulation of amoeboid cells on surfaces, but further research is required to fully understand and model the fine mechanisms governing such transport under γ similar to those encountered in the industrial environment. This technological advance may enable research into these topics.
The viscoelastic properties of yield stress fluids are difficult to measure outside the linear viscoelastic regime, in particular above their yield stress. These properties are investigated for ...several common yield stress fluids using inertio-elastic oscillations. From this coupling between the instrument’s inertia and the viscoelasticity of the materials, the complete simple shear rheology can be determined, including viscoelasticity under flow. Findings show that the tested materials have an almost constant elasticity below and above the yield stress, even for applied stresses several times larger than the yield stress. Moreover, the temporal behavior of the materials is unambiguously determined. Concentrated Xanthan is shown to be thixotropic, while Ketchup mainly shows retarded viscoelasticity. Carbopol does not show long-term temporal dependance but apparently exhibits fracturation.
The aim of this research project was to predict the sound pressure above a wall facing composed of N parallel rectangular cavities. The diffracted acoustic field is processed by generalizing the ...Kobayashi Potential (KP) method used for determining the electromagnetic field diffracted by a rectangular cavity set in a thick screen. This model enables the diffracted field to be expressed in modal form. Modal amplitudes are subsequently calculated using matrix equations obtained by enforcing boundary conditions. Solving these equations allows the determination of the total reflected acoustic field above the wall facing. This model was compared with experimental results obtained in a semi-anechoic room for a single cavity, a periodic array of three rectangular cavities and an aperiodic grating of nine rectangular cavities of different size and spacing. These facings were insonified by an incident spherical acoustic field, which was decomposed into plane waves. The validity of this model is supported by the agreement between the numerical and experimental results observed.
Chitosan obtained from isolated chitin of shrimp shells by a modified chemical method with a high degree of deacetylation to improve its solubility. This was undergoing a graft copolymerization ...process to prepare acetyl chitosan (NACS), acetyl chitosan grafted polylactide (NACS-g-PLA), chitosan grafted polylactide (CS-PLA), and polylactide chitosan grafted poly(ethylene glycol) (CS- PLA-g-PEG) nanoparticles. They characterized by FT-IR and 1HNMR. Chitosan and its derivative nanoparticles morphology examined using SEM and average nanoparticle size counted by ImageJ program. After treatment with chitosan derivative nanoparticles (1 mg/mL) at various time intervals (24, 48 and 72 hour) for three different models of human breast cancer cell lines which are BT, MCF-7 and SKBR3 cell lines, the cell proliferation, cell viability percentage, and genotoxicity as a DNA fragmentation index (%DFI) were analysed by MTT assay, and flow cytometry techniques. The results displayed that CSNPs and its derivatives NACS-g-PLA, CS-g-PLA NPs, and CS- PLA-g-PEG, have strong antitumor activities by inducing in vitro treated BT, MCF-7, and SKBR3 cell lines as a highly significant effect, (p < 0.001) on cell proliferation growth as observed with untreated control cells in a different pattern. Furthermore, it can be said since genotoxicity results that prepared polymers NPs were considered as slight /or no effect on the nucleic material of the BT cell lines, as demonstrated as %DFI in compare with positive and negative control samples.
Geometric or acoustical irregularities induces acoustic scattering. In this paper, a generalization of the model proposed by Khanfir et al. 8 (Journal of Sound and Vibration 332 (4) (2013)) to ...determine the scattered acoustic field above gratings of parallel rectangular cavities is developed, addressing the case of gratings of non-parallel rectangular cavities. The results provided by the model were compared both to numerical results, obtained with the finite element method, and to experimental ones. The observed agreement between the analytical predictions and the numerical and experimental results supports the validity of the proposed model. The coupling between the different cavities was investigated, in order to attain an explanation for its dependence on frequency and on the spacing between cavities.
Building Information Modeling (BIM), in the last couple of decades, has emerged as a technology that can be used in combination with different methodologies in the fields of architecture, ...engineering, and construction industry as a digital model to facilitate the planning and design process, construction and maintenance. Using the tools of BIM, the stakeholders generate the digital models that can help them to identify the problems. A total of 24 conference papers, referenced journal articles, and other academic sources were analyzed based on their relevance and research focus areas. This article provides a review on the integration of building information modeling with different methodologies for seismic retrofitting of both structural and non-structural components of buildings. Pre-seismic and post-seismic applications of Building Information Modeling with the integration of different methodologies have been reviewed overbuilding life cycles with a view of addressing the challenges and recommending the future research perspectives. In the end, by stating the possibilities of integration of BIM tools with different methodologies mainly using Performance-Based Earthquake Engineering as a paradigm which is fully probabilistic, this paper concludes that the implication of the Building Information Modeling with the integration of different methodologies isnt merely the inclusion of the certain conditions, but also of the numerical integration of all the possible uncertainties.
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