Comment on “The diatomic dication CuZn2+ in the gas phase” [J. Chem. Phys. 135, 034306 (2011)]

In this Comment, the density functional theory (DFT) calculations carried out by Diez et al. [J. Chem. Phys. 135, 034306 (2011)10.1063/1.3613624] are revised within the framework of the coupled-cluster single double triple method. These more sophisticated calculations allow us to show that the 2Σ+ electronic ground state of CuZn2+, characterized as the metastable ground state by DFT calculations, is a repulsive state instead. The 2Δ and 2Π metastable states of CuZn2+, on the other hand, should be responsible for the formation mechanism of the dication through the near-resonant electron transfer CuZn+ + Ar+ → CuZn2+ + Ar reaction.Fil: Pis Diez, Reinaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Franzreb, Klaus. Arizona State University; Estados UnidosFil: Alonso, Julio A.. Universidad de Valladolid; Españ

A comparison of quality, value, histological and palatability characteristics of pork carcasses of varying weights

Forty-eight barrow and forty-eight gilt carcasses (n=96). ranging from 66 to 102 kg hot carcass weight and 1.52 to 4.32 cm average backfat thickness with moderately thick being the minimum acceptable muscling score, were selected from a local Knoxville, Tennessee packing plant, identically fabricated and evaluated for various quality, value, histological and palatability characteristics. Mean longissimus areas measured at the second, fifth and tenth ribs were all significantly greater (P\u3c.01) for the trimmer carcasses (1.52 to 2.29 cm) and gilts had significantly larger (P\u3c.01) longissimus areas at the second and tenth ribs than barrows. Mean marbling and lean firmness scores were nonsignificant with respect to average backfat thickness and hot carcass weight, but marbling scores were higher (P\u3c.01) for barrows and displayed a significant interaction (P\u3c.01) between hot carcass weight x sex. Lean firmness scores had significant interactions (P\u3c.05) for backfat x hot carcass weight and backfat x sex. Visual lean color scores were highly significant with respect to Hunter L color-difference values (P\u3c.0001) and Hunter b values (P\u3c.01) but nonsignificant with respect to Hunter a^ values. Percents ham, loin, picnic shoulder and belly as well as per cent of the four lean cuts, percent primal cuts and percent ham-loin were all nonsignificant with respect to hot carcass weight and sex condition with the exception of percent lean cuts where gilts had significantly higher (P\u3c.05) percentages than barrows. Heavier carcasses (P\u3c.01) and trimmer carcasses (P\u3c.001) were significantly greater with respect to Boston butt. Percentage lean in various bacon slices decreased significantly (P\u3c.05) only as average backfat thickness increased. Mean percentages of water and fat (on both a wet and dry basis) were not significantly different (P\u3c.01) with respect to hot carcass weight or sex condition. Fatter carcasses had significantly lower (P\u3c.01) water percentages and trimmer carcasses had significantly lower (P\u3c.01) fat percentages. Percents volatile, nonvolatile and total cooking losses were not significantly different (P\u3c.01) with respect to hot carcass weight or sex condition, but nonvolatile cooking losses were significantly lower (P\u3c.001) for trimmer carcasses (1.52 to 2.29 cm). Mean fiber diameters were significantly different (P\u3c.05) only with respect to the backfat x sex interaction. Mean scores for flavor, juiciness, tenderness and overall acceptability of pork loin chops were nonsignificant (P\u3c.01) with respect to hot carcass weight and sex condition but were significantly lower (P\u3c001) for loin chops from trimmer carcasses (1.52 to 2.29 cm) across all hot carcass weight groups. Although small, R-squared values for Warner-Bratzler Shear, muscle fiber diameter, fat percentage (wet basis) and volatile, non volatile and total cooking losses were highly significant (P\u3c.0001) with respect to all palatability traits. Mean weights for all wholesale cuts increased in a linear fashion with increasing hot carcass weights with no differences attributed to sex condition (P\u3c.01). Loin and belly weights were not significantly different (P\u3c.01) with respect to average backfat thickness, while ham, Boston butt and picnic shoulder weights were significantly lower (P\u3c.01) for fatter (3.56 to 4.32 cm) carcasses. Mean cooking losses for hams decreased with increased carcass fatness (P\u3c.001) but increased with increasing hot carcass weights (P\u3c.001). Mean cooking losses for bellies significantly decreased (P\u3c.001) with increased carcass fatness but were not significantly different (P\u3c.01) with respect to hot carcass weight. Hams were nonsignificant and bellies were significant (P\u3c.05) with respect to cooking losses and sex condition with gilts having greater belly cooking losses than barrows. It was concluded that carcass quality and cutability is at least maintained or possibly improved with respect to increased slaughter weights as long as backfat deposition is adequately controlled with trimmer carcasses generally having greater total values. This would indicate that it would be beneficial for packers to pay producers premiums for heavier hogs that yield carcasses of superior merit

Simulation-based evaluation of single pass continuous diafiltration with alternating permeate flow direction

In the framework of modern bioprocessing continuous ultrafiltration/diafiltration (UF/DF) is getting increasingly popular. However, while continuous UF can be easily implemented using a so-called single pass tangential flow filtration (SPTFF) module, continuous DF requires a more complicated setup including several SPTFF modules and intermittent dilution steps. Recently, we introduced a novel module design for continuous DF allowing simultaneous delivery of fresh buffer while withdrawing the permeate, thus achieving high degrees of buffer exchange within a single unit. In addition, the system allows to cyclically switch the flow direction of DF buffer through the membranes. Those uncommon features, however, also make it more difficult to determine an operation optimum experimentally by means of trial and error. Therefore, here a detailed finite element model of the physical processes within the module is presented, predicting key figures such as the obtained diafiltration efficiency and the resulting pressures. Because within the module all flow channels are filled by a 3D-printed porous grid supporting the membranes from both sides, the modified Brinkman equation was used to simulate the hydrodynamics, while common mass balance differential equations including accumulation, convection, and an anisotropic dispersion term were used for the simulation of concentration profiles of dissolved species. The predicted key figures are in good agreement with experimental results, obtained for feed solutions including up to 50 g/L of protein and being operated with and without switching the flow direction of the diafiltration buffer. A thorough parameter study reveals that the module shows the best performance for unidirectional flow of the diafiltration buffer, reaching diafiltration efficiencies independence to the applied diavolumes which are comparable to the ones of a conventional multi-stage setup using three SPTFF modules. Therefore, the simulation-based evaluation of optimum operation conditions reveals that the new module design has the potential to realize truly continuous diafiltration setups with high efficiency, requiring only one unit and no extra external piping for returning diafiltration in counterflow. Such simplified setups should be especially useful in small, flexible processing plants as they are increasingly demanded in the biopharmaceutical industry

Continuous ultrafiltration/diafiltration using a 3D‐printed two membrane single pass module

A 3D printed ultrafiltration/diafiltration (UF/DF) module is presented allowing the continuous, simultaneous concentration of retained (bio-)molecules and reduction or exchange of the salt buffer. Differing from the single-pass UF concepts known from the literature, DF operation does not require the application of several steps or units with intermediating dilution. In contrast, the developed module uses two membranes confining the section in which the molecules are concentrated while the sample is passing. Simultaneously to this concentration process, the two membranes allow a perpendicular in and outflow of DF buffer reducing the salt content in this section. The module showed the continuous concentration of a dissolved protein up to a factor of 4.6 while reducing the salt concentration down to 47% of the initial concentration along a flow path length of only 5 cm. Due to single-pass operation the module shows concentration polarization effects reducing the effective permeability of the applied membrane in case of higher concentration factors. However, because of its simple design and the capability to simultaneously run UF and DF processes in a single module, the development could be economically beneficial for small scale UF/DF applications

Simulative Minimization of Mass Transfer Limitations Within Hydrogel-Based 3D-Printed Enzyme Carriers

In biotechnology, immobilization of functional reactants is often done as a surface immobilization on small particles. Examples are chromatography columns and fixedbed reactors. However, the available surface for immobilization is directly linked to particle diameter and bed porosity for these systems, leading to high backpressure for small particle sizes. When larger molecules, such as enzymes are immobilized, physical entrapment within porous materials like hydrogels is an alternative. An emerging technique for the production of geometrically structured, three-dimensional and scalable hollow bodies is 3D-printing. Different bioprinting methods are available to produce structures of the desired size, resolution and solids content. However, in case of entrapped enzymes mass transfer limitations often determine the achievable reactivities. With increasing complexity of the system, for example a fixed-bed reactor, 3D-simulation is indispensable to understand the local reaction conditions to be able to highlight the optimization potential. Based on experimental data, this manuscript shows the application of the dimensionless numbers effectiveness factor and Thiele modulus for the design of a 3D-printed flow-through reactor. Within the reactor, enzymes are physically entrapped in 3D-printed hydrogel lattices. The local reaction rate of the enzymes is directly dependent on the provided substrate amount at the site of reaction which is limited by the diffusion properties of the hydrogel matrix and the diffusion distance. All three parameters can be summed up by one key figure, the Thiele modulus, which, in short, quantifies mass transfer limitations of a catalytic system. Depending on the rate of the enzymatic reaction in correlation to the diffusional transport, mass transfer limitations will shift the optimum of the system, favoring slow enzyme kinetics and small diffusion distances. Comparison with the enzymatic reaction rate in solution yields the effectiveness factor of the system. As a result, the optimization potential of varying the 3D-printed geometries or the reaction rate within the experimentally available design space can be estimated

Configurable 3D Printed Microfluidic Multiport Valves with Axial Compression

In the last decade, the fabrication of microfluidic chips was revolutionized by 3D printing. It is not only used for rapid prototyping of molds, but also for manufacturing of complex chips and even integrated active parts like pumps and valves, which are essential for many microfluidic applications. The manufacturing of multiport injection valves is of special interest for analytical microfluidic systems, as they can reduce the injection to detection dead volume and thus enhance the resolution and decrease the detection limit. Designs reported so far use radial compression of rotor and stator. However, commercially available nonprinted valves usually feature axial compression, as this allows for adjustable compression and the possibility to integrate additional sealing elements. In this paper, we transfer the axial approach to 3D-printed valves and compare two different printing techniques, as well as six different sealing configurations. The tightness of the system is evaluated with optical examination, weighing, and flow measurements. The developed system shows similar performance to commercial or other 3D-printed valves with no measurable leakage for the static case and leakages below 0.5% in the dynamic case, can be turned automatically with a stepper motor, is easy to scale up, and is transferable to other printing methods and materials without design changes

Predicting the potential of capacitive deionization for the separation of pH‐dependent organic molecules

One of the main steps in the biotechnological production of chemical building blocks, such as, e.g. bio-based succinic acid which is used for lubricants, cosmetics, food, and pharmaceuticals, is the isolation and purification of the target molecule. A new approach to isolate charged, bio-based chemicals is by electrosorption onto carbon surfaces. In contrast to ion exchange, electrosorption does not require additional chemicals for elution and regeneration. However, while the electrosorption of inorganic salts is well understood and in commercial use, the knowledge about electrosorption of weak organic acids including the strong implications of the pH-dependent dissociation and their affinity towards physical adsorption must be expanded. Here, we show a detailed discussion of the main pH-dependent effects determining the achievable charge efficiencies and capacities. An explicit set of equations allows the fast prediction of the named key figures for constant voltage and constant current operation. The calculated and experimental results obtained for the electrosorption of maleic acid show that the potential-free adsorption of differently protonated forms of the organic acid play a dominating role in the process. At pH 8 and a voltage threshold of 1.3 V, charge efficiencies of 25% and capacities around 40 mmol/kg could be reached for a constant current experiment. While this capacity is clearly below that of ion exchange resins, the required carbon materials are inexpensive and energy costs are only about 0.013 €/mol. Therefore, we anticipate that electrosorption has the potential to become an interesting alternative to conventional unit operations for the isolation of charged target molecules

Practical Insights into the Impedance Response of Interdigitated Electrodes: Extraction of Relative Static Permittivity and Electrolytic Conductivity

This work aims to provide a detailed understanding of the challenges related to the computation of the relative static permittivity and electrolytic conductivity of a sample medium from its impedance response recorded with interdigitated electrode (IDE) geometries. Within the scope of the study, impedance data has been measured and evaluated for a total of nine sample media using two distinct IDE geometries. Particular emphasis is laid upon the compensation of parasitic influences affecting the impedance response. With the raw data supporting this study fully disclosed, the reader is offered the opportunity to comprehensively retrace the evaluation procedure proposed in the text