Background
Robust data on quality of life (QoL) after different techniques of bariatric surgery are sparse. This RCT compared excess weight loss (EWL) and QoL after sleeve gastrectomy versus ...Roux‐en‐Y gastric bypass (RYGB).
Methods
Obese patients were assigned randomly to RYGB or sleeve gastrectomy. The primary outcome measure was EWL. Secondary outcomes included QoL, co‐morbidity, adverse events, vitamin and glycolipid status. QoL was assessed before and annually after surgery, using the Moorehead–Ardelt Quality of Life Questionnaire II (M‐A‐QoLQII) and Gastrointestinal Quality of Life Index (GIQLI).
Results
One hundred patients were enrolled, 45 in the RYGB group and 55 in the sleeve gastrectomy group. Mean postoperative EWL at 1, 2, 3 and 5 years was 80·4, 79·8, 83·0 and 74·8 per cent respectively after RYGB, and 83·0, 77·8, 66·3 and 65·1 per cent after sleeve gastrectomy (P = 0·017). Mean M‐A‐QoLQII score before surgery and at 1, 2, 3 and 5 years after operation was 0·5, 1·6, 1·7, 2·1 and 1·4 respectively after RYGB, and 0·3, 1·7, 1·5, 1·5 and 1·2 after sleeve gastrectomy. Mean GIQLI score before and at 1, 2, 3, 5 years after RYGB was 96·4, 113·8, 113·3, 113·4, 111·7, compared with 90·7, 113·9, 114·5, 113·1 and 113·0 for sleeve gastrectomy. The improvement was significant compared with preoperative values (P < 0·001 for M‐A‐QoLQII and GIQLI), with no difference between groups (P = 0·418 and P = 0·323 respectively). RYGB resulted in higher readmission rates (P = 0·002) and length of hospital stay (P = 0·006) than sleeve gastrectomy.
Conclusion
RYGB and sleeve gastrectomy resulted in equivalent, long‐standing QoL improvement. RYGB resulted in more stable weight loss but was associated with higher readmission rates. Registration number: NCT02475590.
Bypass better in the long term
► Integrated R-DWC for the eco-efficient synthesis of FAME by FFA esterification. ► Optimal reactive-DWC design based on sequential quadratic programming (SPQ). ► Vapor methanol feed imperative for ...the process dynamics and efficient control. ► Singular value decomposition (SVD) used for inferential temperature control. ► Rigorous steady-state and dynamic simulations in Aspen Plus and Dynamics.
Reactive separation technologies were proposed recently for fatty acid methyl esters (FAME) production, providing significant benefits such as minimal capital and operating cost savings. One approach is to use a reactive dividing-wall column (R-DWC) for the biodiesel production process. However, since the R-DWC is designed for a quaternary reactive system – two reactants (one in excess) and two products – more difficulties concerning the process control may be expected considering the high degree of integration of the process.
This study is among the first to tackle the optimal design, dynamics and control of such an integrated unit and proposes an efficient control structure for a biodiesel process based on reactive DWC technology. AspenTech Aspen Plus and Aspen Dynamics were used as computer aided process engineering (CAPE) tools to perform the rigorous steady-state and dynamic simulations, as well as the optimization of the new R-DWC based biodiesel process. A key finding of this study is that it is imperative to use a vapor feed of alcohol in order to reach the product specifications. Singular value decomposition (SVD) was used to determine the sensitive trays for inferential temperature control. The control structure proposed here demonstrates the excellent performance of the system in the case of industrially relevant disturbances such as production rate changes or catalyst deactivation.
Four kinds of spinel ferrites, MeFe2O4 (Me = Cu, Ni, Zn and Cd), were prepared by so called “selfcombustion method” using nitrates as precursors. The morphological and structural characterization of ...the ferrite powders have been performed with various techniques: X-ray diffraction (XRD), to determine the phase composition, SEM observations to evaluate nanostructure characteristics, EDAX spectroscopy to evaluate the chemical composition and BET analysis to determine the specific surface area. The ferrite powders have been tested catalytically in combustion reaction of three diluted gases: acetone/air, ethanol/air and methanol/air. The results revealed a pronounced decrease in the combustion temperature when Cu- and Ni-ferrites are used as catalysts. A probable cause was ascribed to multiple valences of Cu and Ni ions which favor a rapid increase in the oxygen ion species adsorbed on ferrite surface.
► A simple and low cost method was used for preparation MeFe2O4 (Me = Cu, Ni, Zn, Cd). ► XRD and SEM confirm spinel structure and nanosized of crystallites (33–52 nm). ► The metal-type has a strong influence on the minimum combustion temperature. ► CuFe2O4 and NiFe2O4 ferrites show superior catalytic activity. ► The catalytic activity of ferrites is controlled by the O2 ion vacancies.
•Molecular dynamics of single crystal copper nanowires with silver impurities under tensile stress.•Silver impurities lower the yield strength of the material.•Impurity atoms lower slightly the ...unstable stacking fault energy, promoting the nucleation of partial dislocations.
The transition from elastic to plastic behaviour in single crystal copper nanowires under uniaxial tensile stress at different concentrations of silver (0.0–0.5at.% Ag) and at different temperatures (0.1, 100, and 300K) using the molecular dynamics method is investigated. The tensile stress is applied along 〈100〉 crystallographic orientation and the silver atoms are placed randomly on the surface of the nanowire, as substitutional point defect. The simulations indicate that silver atoms lower slightly the unstable stacking fault energy, making them act as sources of partial dislocation nucleation, due to the local strain field they produce in the lattice structure. The defects generated in the material also act as sources for nucleation, giving rise to a competition of two mechanism. Also, it is observed that the yield point decreases with the temperature and the presence of impurities.
Application of dilational surface rheology, surface tensiometry, ellipsometry, Brewster angle, and transmission electron and atomic force microscopies allowed the estimation of the structure of the ...adsorption layer of a fullerenol with a large number of hydroxyl groups, C60(OH) X (X = 30 ± 2). The surface properties of fullerenol solutions proved to be similar to the properties of dispersions of solid nanoparticles and differ from those of the solutions of conventional surfactants and amphiphilic macromolecules. Although the surface activity of fullerenol is not high, it forms adsorption layers of high surface elasticity up to 170 mN/m. The layer consists of small interconnected surface aggregates with the thickness corresponding to two–three layers of fullerenol molecules. The aggregates are not adsorbed from the bulk phase but formed at the interface. The adsorption kinetics is controlled by an electrostatic adsorption barrier at the interface.
A new type of nanocomposite containing SnO(2) has been obtained by wet impregnation of dehydrated Mg/Al-hydrotalcite-type compounds with ethanolic solutions of SnCl(4).2H(2)O. Tin chloride hydrolysis ...was achieved using NaOH or NH(4)OH aqueous solutions, at pH around 9, followed by the conversion into corresponding hydroxides through calcinations. The powder X-ray diffraction (PXRD) and UV-Vis diffuse reflectance (UV-DR) methods confirmed the structure of as-synthesized solids. The chemical composition and morphology of the synthesized materials were investigated by energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-synthesized materials were used for photocatalytic studies showing a good activity for methylene blue decolourization, which varies with SnO(2) content and used as a hydrolysing agent. The proposed mechanism is based on the shifting of flat band potential of SnO(2) due to the interaction with Mg/Al-LDH, this being energetically favourable to the formation of hydroxyl radicals responsible for methylene blue degradation.
“Wet” and “dry” template methods were used to simultaneously control the pore size, morphology, and graphitization in structurally well-ordered mesoporous carbons. A novel structure has been prepared ...using glycerol as the carbon source. Depending on the loading amount of the glycerol, the structural characteristics of the mesoporous carbon materials can be controlled. The structurally well-ordered carbon materials have been characterized by various techniques such as nitrogen sorption, XRD, Raman spectroscopy, TGA measurements and SEM. They have graphitic character, high BET surface area (ca 1440m2/g) and a tunable pore size. They are likely to be useful in a variety of applications including gas storage, electrode materials or catalyst supports.
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► One step bioethanol concentration and dehydration in an extractive dividing-wall column. ► Energy efficient anhydrous bioethanol production in an integrated 3-in-1 distillation ...unit. ► Ethanol dehydration (from 10 to 99.8%wt) using ethylene glycol as mass separating agent. ► Energy savings of 17% with similar reduction in capital investment costs. ► Rigorous simulations, sensitivity analysis and optimization performed in Aspen Plus.
The large-scale production of bioethanol fuel requires energy demanding distillation steps to concentrate the diluted streams from the fermentation step and to overcome the azeotropic behavior of the ethanol–water mixture. The conventional separation sequence consists of three distillation columns performing several tasks with high energy penalties: pre-concentration of ethanol, extractive distillation and solvent recovery. Despite the novel recent developments in pervaporation and adsorption with molecular sieves, the industrial production of anhydrous bioethanol is still dominated by extractive distillation as the separation method of choice.
This study proposes an innovative distillation setup – based on a novel extractive dividing-wall column (E-DWC) – that is able to concentrate and dehydrate bioethanol in a single step, by integrating all units of the conventional sequence into only one distillation column. In this work, a mixture of 10wt% ethanol (100ktpy plant) is concentrated and dehydrated using ethylene glycol as mass separating agent. Rigorous simulations were carried out in Aspen Plus, and for a fair comparison all alternatives were optimized using the reliable sequential quadratic programming (SQP) method. The results show that energy savings of 17%, and a similar decrease in CapEx, are possible for the novel E-DWC alternative, while using a significantly reduced footprint as compared to the conventional separation process.
n the last years, much attention has been focused on the use of low-cost adsorbents for the removal of Cu(II) and Zn(II) from contaminated waters. In this context, we studied the sorption ...performances of two kinds of by-products resulted from the agriculture: soy bran and mustard husk. The effects of contact time, the initial metal ion concentration, pH, sorbent mass, and temperature on the adsorption capacity of the agricultural by-products as sorbents were investigated. The thermodynamic parameters associated with the adsorption process indicated that the process is spontaneous and endothermic. Modeling of experimental adsorption isotherm data showed that non-linear Langmuir isotherm fits better than other isotherms. The obtained values for the separation factor,
R
L
were less than one which supports that the adsorption process was favorable. The obtained results indicated that the soy bran has a higher sorption capacity toward zinc ions (74.02 mg g
−1
) than mustard husk (63.69 mg g
−1
). Therefore, there is a great requirement for the search of biomaterials that are cheap and easily available for the removal of heavy metal ions from wastewater. The studied sorbents have the advantage of very low cost and great availability for simple operational experiments.
Process intensification techniques were recently proposed to improve the eco‐efficiency of the conventional dimethyl ether (DME) purification and methanol recovery distillation sequence, but they all ...require new specific equipment and hence rather high investment costs leading to several years of payback time. However, the alternative of reusing the existing equipment to revamp the two distillation columns of the downstream processing section into a single‐step separation was so far overlooked in the open literature. To solve the problem of costly DME separation, a novel single‐step DME separation taking place in a dividing‐wall column (DWC) is proposed that effectively integrates in one shell the tasks of DME purification and methanol recovery. The new process is optimized in terms of minimal energy requirements, taking into account the restrictions caused by reusing one distillation column like, such as limited diameter or reboiler/condenser heat duty. The results demonstrate that the DWC alternative is feasible and has better performances as compared to the classic sequence, i.e., 28 % lower operating costs and 20 % less capital investment.
For the first time it is demonstrated that the conventional dimethyl ether DME purification and methanol recovery distillation sequence can be effectively converted into a single‐step separation based on the dividing‐wall column (DWC) technology. The novel proposed DWC alternative decreases the energy requirements by 28 % and the equipment costs by 20 %.
