Establish Design Criteria Research Articles

Research on the Jet Distance Enhancement Device for Blueberry Harvesting Robots Based on the Dual-Ring Model

In China, most blueberry varieties are characterized by tightly clustered fruits, which pose challenges for achieving precise and non-destructive automated harvesting. This complexity limits the design of robots for this task. Therefore, this paper proposes adding a jetting step during harvesting to separate fruit clusters and increase the operational space for mechanical claws. First, a combined approach of flow field analysis and pressure-sensitive experiments was employed to establish design criteria for the number, diameter, and inclination angle parameters of two types of nozzles: flat tip and round tip. Furthermore, fruit was introduced, and a fluid–structure coupling method was employed to calculate the deformation of fruit stems. Simultaneously, a mechanical analysis was conducted to quantify the relationship between jet characteristics and separation gaps. Simulation and pressure-sensitive experiments show that as the number of holes increases and their diameter decreases, the nozzle’s convergence becomes stronger. The greater the inclination angle of the circular nozzle holes, the more the gas diverges. The analysis of the output characteristics of the working section indicates that the 8-hole 40° round nozzle is the optimal solution. At an air compressor working pressure of 0.5 MPa, force analysis and simulation results both show that it can increase the picking space for the mechanical claw by about 5–7 mm without damaging the blueberries in the jet area. The final field experiments show that the mean distance for Type I (mature fruit) is 5.41 mm, for Type II (red fruit) is 6.42 mm, and for Type III (green fruit) is 5.43 mm. The short and curved stems of the green fruit are less effective, but the minimum distance of 4.71 mm is greater than the claw wall thickness, meeting the design requirements.

Advancing Ion Separation: Covalent-Organic-Framework Membranes for Sustainable Energy and Water Applications.

ConspectusMembranes are pivotal in a myriad of energy production processes and modern separation techniques. They are essential in devices for energy generation, facilities for extracting energy elements, and plants for wastewater treatment, each of which hinges on effective ion separation. While biological ion channels show exceptional permeability and selectivity, designing synthetic membranes with defined pore architecture and chemistry on the (sub)nanometer scale has been challenging. Consequently, a typical trade-off emerges: highly permeable membranes often sacrifice selectivity and vice versa. To tackle this dilemma, a comprehensive understanding and modeling of synthetic membranes across various scales is imperative. This lays the foundation for establishing design criteria for advanced membrane materials. Key attributes for such materials encompass appropriately sized pores, a narrow pore size distribution, and finely tuned interactions between desired permeants and the membrane. The advent of covalent-organic-framework (COF) membranes offers promising solutions to the challenges faced by conventional membranes in selective ion separation within the water-energy nexus. COFs are molecular Legos, facilitating the precise integration of small organic structs into extended, porous, crystalline architectures through covalent linkage. This unique molecular architecture allows for precise control over pore sizes, shapes, and distributions within the membrane. Additionally, COFs offer the flexibility to modify their pore spaces with distinct functionalities. This adaptability not only enhances their permeability but also facilitates tailored interactions with specific ions. As a result, COF membranes are positioned as prime candidates to achieve both superior permeability and selectivity in ion separation processes.In this Account, we delineate our endeavors aimed at leveraging the distinctive attributes of COFs to augment ion separation processes, tackling fundamental inquiries while identifying avenues for further exploration. Our strategies for fabricating COF membranes with enhanced ion selectivity encompass the following: (1) crafting (sub)nanoscale ion channels to enhance permselectivity, thereby amplifying energy production; (2) implementing a multivariate (MTV) synthesis method to control charge density within nanochannels, optimizing ion transport efficiency; (3) modifying the pore environment within confined mass transfer channels to establish distinct pathways for ion transport. For each strategy, we expound on its chemical foundations and offer illustrative examples that underscore fundamental principles. Our efforts have culminated in the creation of groundbreaking membrane materials that surpass traditional counterparts, propelling advancements in sustainable energy conversion, waste heat utilization, energy element extraction, and pollutant removal. These innovations are poised to redefine energy systems and industrial wastewater management practices. In conclusion, we outline future research directions and highlight key challenges that need addressing to enhance the ion/molecular recognition capabilities and practical applications of COF membranes. Looking forward, we anticipate ongoing advancements in functionalization and fabrication techniques, leading to enhanced selectivity and permeability, ultimately rivaling the capabilities of biological membranes.

The Impact of Administrative Buildings on the Psychology of Users and Its Relationship to Increasing Productivity for Occupants

This study aimed to investigate the overall impact of administrative building design on the psychology of users and its effect on the work environment and employee productivity. It also aimed to establish design criteria for creating a work environment that aligns with the physiological and psychological needs of employees. The deductive approach was adopted in this study, and a questionnaire was used to gather the necessary data. One of the key findings was the relationship between the built environment of the workplace and the psychology of users on employee productivity. As a result, several recommendations were made, including urging engineers to pay attention to implementing the necessary design standards that consider the physiological and psychological needs of employees, making them fundamental design principles for creating a high-quality work environment that not only enhances employee productivity but also has a positive impact on their physical and mental health, as well as their relationships with the surroundings, which, in turn, has a consequential effect on society as a whole.

Exploring the effect of axial wall conduction on the heat transfer mechanism of hourglass microchannels: Design guidelines for maintaining a constant wall temperature

To accurately estimate the heat transfer mechanisms of microscale thermal devices, it is essential to quantify the effects of axial wall conduction, which can significantly alter the thermal boundary conditions. This study focuses on exploring the effect of axial wall conduction on the thermal mechanism of hourglass microchannels, a topology that has proven useful in several engineering applications. However, there is a lack of research on the impact of axial wall conduction on the heat transfer mechanism of hourglass microchannels, and their potential for maintaining constant temperatures in biological applications has not been explored. To address this issue, a three-dimensional numerical analysis is conducted to investigate the impact of various design variables on the thermal mechanics of hourglass microchannels. An experiment has also been performed to validate the numerical approach employed in the study. The results show that the axial wall conduction effect is insignificant for modified Maranzana number below 0.01. It is further noted that the Nusselt number attains a maximum at an intermediate thermal conductivity ratio. This ratio ranges from 27 to 246 and is moderately dependent on the convergence-divergence angle, width ratio, and thickness ratio. Interestingly, an hourglass shape can maintain a near-isothermal boundary condition with a temperature difference of 1.4K at a lower width ratio. This work also establishes the design criteria for achieving a nearly isothermal condition within prescribed limits for important parameters, such as convergence-divergence angle (8°-16°), width ratio (1–2), thermal conductivity ratio (>646), thickness ratio (>10), and Reynolds number (>300). The established design criteria will pave the way for developing lab-on-chip devices for biological applications, such as PCR, that require the maintenance of constant wall temperature.

Characterization of the Temporomandibular Joint Disc Complex in the Yucatan Minipig.

The temporomandibular joint (TMJ) disc complex (i.e., the TMJ disc and its six attachments) is crucial to everyday functions such as mastication and speaking. The TMJ can be afflicted by many conditions, including disc displacement and defects. Pathologies of the TMJ disc complex most commonly present first as anterior disc displacement, which the field hypothesizes may implicate the two posterior attachments. As a result of anterior disc displacement, defects may develop in the lateral disc complex. Tissue engineering is poised to improve treatment paradigms for these indications of the TMJ disc complex by engineering biomimetic implants, but, first, gold-standard design criteria for such implants should be established through characterization studies. This study's objective was to characterize the structural, mechanical, biochemical, and crosslinking differences among the two posterior attachments and the lateral disc in the Yucatan minipig, a well-accepted TMJ animal model. In tension, it was found that the posterior inferior attachment (PIA) was significantly stiffer and stronger by 2.13 and 2.30 times, respectively, than the posterior superior attachment (PSA). It was found that collagen in both attachments was primarily aligned mediolaterally; however, the lateral disc was much more aligned and anisotropic than either attachment. Among the three locations, the PSA exhibited the greatest degree of heterogeneity and highest proportion of fat vacuoles. The PIA and lateral disc were 1.93 and 1.91 times more collagenous, respectively, by dry weight (DW) than the PSA. The PIA also exhibited 1.78 times higher crosslinking per DW than the PSA. Glycosaminoglycan per DW was significantly higher in the lateral disc by 1.48 and 5.39 times than the PIA and PSA, respectively. Together, these results establish design criteria for tissue-engineering of the TMJ disc complex and indicate that the attachments are less fibrocartilaginous than the disc, while still significantly contributing to the mechanical stability of the TMJ disc complex during articulation. These results also support the biomechanical function of the PIA and PSA, suggesting that the stiffer PIA anchors the disc to the mandibular condyle during articulation, while the softer PSA serves to allow translation over the articular eminence. Impact Statement Characterization of the temporomandibular joint (TMJ) disc complex (i.e., the disc and its attachments) has important implications for those aiming to tissue-engineer functional replacements and can help elucidate its biomechanical function. For example, the findings shown here suggest that the stiffer posterior inferior attachment anchors the disc during articulation, while the softer posterior superior attachment allows translation over the articular eminence.

Intrinsic ion transport of highly charged sub-3-nm boron nitride nanotubes

Debate regarding the transport mechanisms of water and ions in highly charged one-dimensional (1D) nanochannel continues because of a lack of available experimental data. Here, we present a nanofluidic platform consisting of ≈2.7-nm-diameter boron nitride nanotubes (BNNTs) as a model system, and report the experimental ion transport in these sub-3-nm BNNTs. We elucidate that strong electrostatic interactions between the highly charged tube walls and ions, stemming from the high surface-charge density (378 mC/m2) of BNNTs, play important roles in defining the ion transport mechanism in BNNT pores. Experimental analysis of ion transports supported by numerical the Donnan steric pore model with dielectric exclusion (DSPM-DE) and Derjaguin–Landau–Verwey–Overbeek (DLVO) model elucidate the relationship of the ionic charge density and surface-charge density of the BNNT wall to electrostatic interaction, steric, and dielectric effects. We also demonstrate that BNNTs exhibit higher NaCl separation (≈90%) than commercial reverse-osmosis (≈80%) and nanofiltration (≈60%) membranes under the same experimental conditions, despite having a larger pore size. Our results establish design criteria for developing highly efficient ion-selective membranes for various practical applications.

Predicting Fuel Cell Ink Aggregation

Polymer-electrolyte fuel cells (PEFCs) provide multisector decarbonization solutions including in transportation, manufacturing, and long-term energy storage. They have become increasingly popular in these areas due to their high efficiency, power density, and low (or zero) emissions compared to traditional fossil-fuel dependent processes. The PEFC catalyst layer is the most complex and key part of the cell, and is critical for optimizing PEFC performance. Several studies have explored the structure/function relationships of PEFC catalyst layers, yet the physics and interactions controlling its in-situ formation remain a mystery. PEFC catalyst layers are traditionally fabricated out of a catalyst supported on a carbon nanoparticle with an ionomer, traditionally perfluorosulfonic acids (PFSAs) such as Nafion, as a binder, which stabilizes the carbon suspensions in the ink dispersion. Recent studies demonstrated the importance of pH as an experimental parameter for both comparison and characterization of such systems.1 In this talk, we explore the interactions in the colloidal inks through detailed mathematical modeling. We propose a kinetics-based model representing species aggregation with pointwise interacting spheres that vary in charge through buried side chains for predicting the aggregation behavior of Nafion and carbon in solutions under varying conditions, such as solvent, Nafion wt% and carbon wt%. To demonstrate the accuracy and robustness of the model, we compare the results against a range of pH conditions and size distributions. The insights from the model help establish design criteria and guide future ink and process conditions.AcknowledgementsThis study was conducted under the Million Miles Fuel Cell Truck Consortium (M2FCT) funded by the Hydrogen and Fuel Cell Technologies Office in the Energy Efficiency and Renewable Energy Office of the U.S. Department of Energy under contract DE-AC02-05CH11231.References S. A. Berlinger, B. D. McCloskey, and A. Z. Weber, J. Phys. Chem. B, 122, 7790–7796 (2018).

A novel approach to interpret quasi-collimated beam results to support design and scale-up of vacuum UV based AOPs

UV-C at 254 nm and vacuum UV (VUV) at 185 nm are the two major emission lines of a low-pressure mercury lamp. Upon absorption of VUV photons, water molecules and selected inorganic anions generate hydroxyl (HO.) and other redox radicals, both capable of degrading organic micropollutants (OMPs), thereby offering the opportunity to reduce H2O2 and energy consumption in UV-based advanced oxidation process (AOP). To be successfully scaled-up, the dual-wavelength VUV+UV/H2O2 AOP requires laboratory-scale experiments to establish design criteria. The figures of merit typically used for reporting and interpreting quasi-collimated beam results for UV-based AOPs (time, dose, absorbed energy and EEO) are insufficient and inaccurate when employed for dual-wavelength AOP such as the VUV+UV/H2O2 AOP, and do not support system scale-up. In this study, we introduce a novel figure of merit, useful absorbed energy (uAE), defined as fraction of absorbed energy that results in the generation of oxidative radicals. Here, results of quasi-collimated beam VUV+UV/H2O2 AOP experiments on four different water matrices are used to introduce 2D plots that employ both uAEUV and uAEVUV as a novel method to represent laboratory-scale experiments of VUV+UV/H2O2 AOP and demonstrate how the 2D plots sufficiently support scale-up of the AOP.

Cognitive Accessibility in Rural Heritage: A New Proposal for the Archaeological Landscape of Castulo

The long-lost Ibero-Roman citadel of Castŭlō, or Castulo as it is known today, has been revealed to be one of the most important centers of the southern Iberian Peninsula due to its size and its geographical position. The ancient walled holdfast occupies an area of about 50 hectares, with overlapping vestiges from different historical stages. During the last intervention in the northwest city walls, a set of important findings was revealed, notably a Roman high-quality relief depicting a lion which holds a human head between its paws. This article, in addition to contextualizing and presenting the archaeological site, focuses on the latest work carried out in the northern area of the city’s Punic wall. Based on the data obtained, an urban interpretation is also provided on the use and function of this walled city area and how it was attuned to the surroundings to configure a new kind of landscape project. Relevant endeavours have been undertaken by the authors in order to render the restoration feasible, and prominently to introduce a more innovative issue of cognitive accessibility for the visitors who are allowed to enjoy this significant piece of heritage despite the hindrances of the terrain. This is the fundamental objective of a former research project by the authors, and it was extended to offer a key to sustainable archaeology, establishing design criteria for the planning of spaces that fulfil the experience of visiting heritage for groups of people with cognitive problems: among them, those with Alzheimer’s disease. By addressing these pending requirements, the sustainable qualities of the archaeological sites would be significantly enhanced.

Design engineering approach to ensuring specified dependability. Case study of unique, highly critical systems with short operation life

Aim. To examine the design engineering approach to ensuring specified dependability on the basis of engineering disciplines and design engineering methods of quality and dependability assurance using the case of unique, highly critical products with short operation life. Such approach, unlike the statistical procedures of modern dependability, allows associating the dependability indicator calculations with the calculated operability parameters and established design criteria that are to be met in order to confirm the specified dependability indicators for products with an indefinite number of critical elements, each of which operates according to a functional principle that is different in its nature. Methods. The paper examined the prerequisites for the implementation of the design engineering approach to dependability, such as the distinctive features of ensuring the dependability of unique, highly critical products with short operation life, the applicability of design engineering approach to dependability, the effect of the genesis on the assurance of design engineering dependability, behavioural models of technical products in terms of dependability and specifics of highly critical product calculation. It was identified that, for items with high specified probability of no failure exceeding three-sigma random value variation interval, dependability is to be calculated not by identifying the dependability function, but rather by proving that undependability function is below the acceptable value, which ultimately ensures the specified dependability. Such approach enables the development of methods of early failure prevention using procedures of design engineering analysis of dependability for the purpose of achieving the required parameters of functionality, operability and dependability of products on the basis of a generalised parametric functional model. Results. The design engineering analysis of dependability allows substantiating the criteria for error-free design (selection of sound principles of operability and validation of engineering solutions for achieving the required dependability indicators). The effect of the error-free engineering criteria combined with the criteria for defect-free engineering (observance of the generally accepted principles, rules, requirements, norms and standards of drawing generation) and defect-free manufacture (strict adherence to the requirements of drawings with no deviation permits) enables a designer to achieve the specified dependability values without using the statistical methods of the modern dependability theory. Conclusion. Dependability as a comprehensive property is characterised by a probability that, on the one hand, determines the rate of possible failures, and, on the other hand, indicates the number of errors that were made by engineers during the design, manufacture and operation of products and can lead to failures. Additionally, the failure rate is determined by the engineers’ efforts to eliminate or mitigate the consequences of possible failures at each life cycle stage. The greater and earlier are such efforts adopted, the higher the product’s dependability will be. Ultimately, dependability is determined by consistent and rigorous implementation of error-free design, defect-free design and defect-free manufacture procedures whose efficiency is in no way associated with the number of manufactured products. Their efficiency and effectiveness are determined by specific decisions and actions by the engineers who make sure that the product performs the required functions with the specified dependability in the established modes and conditions of operation. Ensuring that only takes using engineering disciplines, as well as design engineering methods for quality and dependability assurance.

The distribution, type, popularity, size and availability of river-run gravel and crushed stone for use in land drainage systems and their suitability for mineral soils in Ireland

The performance of land drainage systems installed in mineral soils in Ireland is highly variable, and is dependent on, amongst other factors, the quality and suitability of the aggregate used. In Ireland, aggregate for land drainage systems is usually river-run gravel and crushed stone. This study classified the distribution, type, popularity, size and availability of aggregates for land drainage systems throughout Ireland and quantified their suitability for use in mineral soils. Eighty-six quarries were surveyed. Limestone and river-run gravel (80% of lithologies) are widespread throughout the country. The quarry aggregate sizes (“Q sizes”), reported by the quarries as either a single size, that is, “50 mm”, or a graded size, that is, 20–40 mm, were variable, changed across lithology and region and were, in most cases, larger than what is currently recommended. A particle size distribution analysis of 74 samples from 62 quarries showed that individual Q sizes increased in variability with increasing aggregate size. In some regions, the aggregate sold does not meet current national regulations, which specify an aggregate size ranging from 10 to 40 mm. The suitability of these aggregates for drainage in five soils of different textures was compared using three established design criteria. It was found that the aggregate in use is too large for heavy soil textures and is therefore unsuitable as drainage envelope material. Guidance for contractors, farmers and quarry owners will be required, and investment may be needed by quarries to produce aggregate that satisfies design criteria. An aggregate size, based on one or a combination of established aggregate design criteria, where an analysis of the soil texture is conducted and an appropriate aggregate is chosen based off its 15% passing size, is required.

Intraoperative hyperspectral label-free imaging: from system design to first-in-patient translation

Despite advances in intraoperative surgical imaging, reliable discrimination of critical tissue during surgery remains challenging. As a result, decisions with potentially life-changing consequences for patients are still based on the surgeon’s subjective visual assessment. Hyperspectral imaging (HSI) provides a promising solution for objective intraoperative tissue characterisation, with the advantages of being non-contact, non-ionising and non-invasive. However, while its potential to aid surgical decision-making has been investigated for a range of applications, to date no real-time intraoperative HSI (iHSI) system has been presented that follows critical design considerations to ensure a satisfactory integration into the surgical workflow. By establishing functional and technical requirements of an intraoperative system for surgery, we present an iHSI system design that allows for real-time wide-field HSI and responsive surgical guidance in a highly constrained operating theatre. Two systems exploiting state-of-the-art industrial HSI cameras, respectively using linescan and snapshot imaging technology, were designed and investigated by performing assessments against established design criteria and ex vivo tissue experiments. Finally, we report the use of our real-time iHSI system in a clinical feasibility case study as part of a spinal fusion surgery. Our results demonstrate seamless integration into existing surgical workflows.

Parametric and experiment studies of 3D auxetic lattices based on hollow shell cuboctahedron

As a kind of mechanical metamaterials with negative Poisson’s ratio (NPR), auxetic lattices possess unusual mechanical responses such as higher sensitivity to strain and reversibility after large deformation. Therefore, they are regarded as a potential candidate to sensors, actuators, and optics. Here, we designed four types of auxetic lattices with long stress plateau based on the assembly of hollow shell cuboctahedron. To begin with, experiments along with finite element simulations were performed to probe their auxetic behaviors under uniaxial compression, which give an excellent qualitative and quantitative agreement. To establish design criteria on specific applications, we systematically investigated the mechanical properties of the four kinds of lattices with different volume fractions, including critical stresses, strain–stress curves, strain energy densities, strain-dependent Poisson’s ratios, and the length of stress plateau. The results demonstrate that these lattices can suffer from buckling with NPR in an extended range of volume fractions, and high reversibility was observed in several compressive loadings, which provides insight into energy absorption such as the body protection equipments and smart packaging material

Probabilistic observational method for design of surcharges on vertical drains

Preloading with a surcharge is today commonly used together with prefabricated vertical drains for embankment construction on clayey soil to accelerate primary consolidation and increase strength. Because of considerable uncertainty related mainly to the rate of consolidation, there is a need to account for this in the vertical drain and surcharge design to ensure quality in the embankment construction. Addressing this issue, the paper presents a novel probabilistic design methodology that is compatible with the observational method. The procedure evaluates the suitable surcharge load to be used in combination with a vertical drain design in order to ensure that the established design criteria are satisfied with acceptable probability.

A New Approach to the Consideration and Analysis of Critical Factors in Robotic Machining

The relative low stiffness of industrial robots is a major limitation on the development of flexible and reconfigurable systems in applications in which process forces and vibration lead into significant tool path deviations with respect to the programmed path as in the case of robotic machining. This paper presents a novel factorial procedure that allows for the preliminary study of the main conditions in robotic machining operations and it determines the critical factors that are affecting the machining path of any robotic cell in order to obtain the process conditions with lower path deviations. In this procedure the most influential robotic machining constraints were identified and classified, the factorial design of experiments was used to enable the execution of the experimental tests and the machining tool path deviation predictive methodology (PREMET) was used to determine the cutting tool path deviation between the programmed and the experimental path as a function of the process variables. Experimental trials have been carried out in order to determine the main factors that affect the robotic machining and influence the main constraints of the process, showing a reduction greater than a 36% of the cutting tool path deviation in groove milling of aluminum. The critical factors identified in order of importance are: hardness of the material, location of the workpiece, orientation of milling head relative to working direction and cutting conditions. This procedure can be extended to future factorial studies to improve the precision of robotic machining (in operations such as face milling, contouring, pocketing) and to establish design criteria for machining robotic cells.

Observations of wave attenuation, scour, and subsurface pore pressures acrossbthree marsh restoration sill structures on a sandy bed

With rising sea levels and more frequent exposure to extreme storms, coastlines worldwide are vulnerable to increased erosion and loss of natural marsh lands. In an effort to lessen these impacts, there is a growing practice of adapting hard or “gray” coastline protection techniques to more nature-based features that promote habitat and ecosystem health. Living shoreline marsh restorations utilize natural and naturebased materials to protect marsh shores from erosion while also allowing intertidal flushing to promote the health and diversity of the marsh. Our study investigates three types of living shoreline sill designs exposed to average and storm-energy wave conditions at varying water levels. The sills were designed to mimic constructed sills in practice (rock, oyster shell, tree root wads), but more generally vary in structure porosity and material dissipation potential. Large-scale laboratory experiments were conducted in the large wave flume at the O.H. Hinsdale Wave Research Laboratory. Wave transmission and reflection are used to demonstrate wave attenuation capability of each sill structure. Scour of the sill, bedload sediment transport rates on the seaward and shoreward sides of the sill, and sediment pore-water vertical hydraulic gradients were used to demonstrate the potential for sediment transport and liquefaction. Results will contribute to understanding the effect of sill material porosity and mass on structure stability, and the effectiveness of using green living shoreline sill structures in the continued effort to establish design criteria for living shoreline implementation.

Análisis comparativo de suelo de campo y laboratorio para la medición de su capacidad portante con ensayos de Valor de Soporte de California (CBR) y Cono Dinámico de Penetración (DCP) en la Universidad Técnica de Manabí.


 The purpose of this investigation is to determine direct correlations by means of laboratory tests for the index of resistance to the cut of the Dynamic Cone of Penetration (DCP), with the resistance to cut California Bearing Ratio (CBR) of the soil, where it presents an alternative to establish Design criteria for pavement structures, based on physical and mechanical tests, taking samples by means of soil exploration, they were subsequently processed in the laboratory demonstrating their properties where silts and clays with a high degree of plasticity predominate.
 Correlations proposed by (Van Vuuren, 1969) were taken, which experimentally mentions an equation suitable for all types of soils and the most accurate according to its reliability, the Dynamic Cone developed by (Scala, 1956), which, experimentally presents the following results in the field: The N°1 poll a 4.7% CBR, the N°2 poll a 3.61% CBR and the N°3 poll a 3.37% CBR, these mentioned parameters were obtained in a corresponding way from the DCP index of 40 mm/stroke, 50 mm/stroke, and 54 mm/stroke, in addition to laboratory tests that a more conservative parameter results were obtained for the poll N°1 a CBR of 3.98% the Poll, N°2 a CBR of 3.40% and the Poll N°3 a CBR of 3.20%.
 
 Index Terms— Dynamic Cone of Penetration (DCP), California Bearing Ratio (CBR), Poll, Correlations, Test.

Bone ‘spackling’ paste: Mechanical properties and in vitro response of a porous ceramic composite bone tissue scaffold

Bone defects are treated with bone grafts, replacing damaged or diseased bone tissue with either natural bone or bone substitutes. This study investigates the structure, mechanical properties, and in vitro response of an all-ceramic composite designed for use as a bone ‘spackling’ paste: a formable synthetic bone graft paste used to repair bone defects in place, reacting with CO2 gas in ambient conditions to become a void-filling, rigid scaffold. The composite is comprised of bioactive glass frit and a soluble liquid silicate precursor combined to form an air-setting, open porous scaffold with compressive strength within the low range for trabecular bone (1.3-4.4 MPa). Characterization of scaffolds, with varying amounts of binder, was executed in accordance with established design criteria of porosity, load-bearing capacity, and bioactivity. Bioactivity was assessed via morphological, structural, and chemical changes in surface mineralization that occurred during in vitro immersion in simulated body fluid. All phases of composite specimens were observed to form calcium phosphate minerals, indicating that a chemical change occurred between the bioactive glass and sodium silicate binder phase. Ion exchange between the two phases was likely, as sodium silicate (control) was not found to produce calcium phosphate in the absence of bioactive glass. Of the selected compositions, composites with 7.4 vol% sodium silicate binder were observed to possess the highest open porosity (44 vol%), highest rate of calcium phosphate mineralization, most uniform surface mineral distribution, and largest amount of hydroxycarbonate apatite formation. The structure, mechanical properties, and in vitro response of the composite scaffolds analyzed in this research signify their potential success as bone tissue scaffolds.

Process design of batch reactors using multi-objective optimization for synthesis of butylated urea formaldehyde resins

Butylated urea formaldehyde resins are amino resins that are key intermediates for manufacturing water-resistant paints and coating materials. Owing to the complex kinetics involved in their synthesis, it has been a challenge to establish design criteria for optimum reactor operations. For instance, for better water-resistant properties and for synthesizing specialty nanocomposites, from BUF, maximum butylation and maximum X-condensates (-CH2-O-CH2- linkages) are respectively required, along with minimum free formaldehyde. We, therefore, harness multi-objective optimization approach to establish optimal trade-offs among various mutually conflicting objectives. In particular, we establish process design criteria by performing 2 and 3 objective optimizations and demonstrate that the latter, provides wider range of choices and better trade-offs for reactor operation compared to the former. Further, we also calculate optimal temperature trajectories and reaction times to achieve these objectives. Our findings can be utilized to determine operating conditions for optimizing resin quality of particular specifications.

Insensitivity of Magnetic Coupling to Ligand Substitution in a Series of Tetraoxolene Radical-Bridged Fe2 Complexes.

The elucidation of magnetostructural correlations between bridging ligand substitution and strength of magnetic coupling is essential to the development of high-temperature molecule-based magnetic materials. Toward this end, we report the series of tetraoxolene-bridged FeII2 complexes [(Me3TPyA)2Fe2(RL)]n+ (Me3TPyA = tris(6-methyl-2-pyridylmethyl)amine; n = 2: OMeLH2 = 3,6-dimethoxy-2,5-dihydroxo-1,4-benzoquinone, ClLH2 = 3,6-dichloro-2,5-dihydroxo-1,4-benzoquinone, Na2[NO2L] = sodium 3,6-dinitro-2,5-dihydroxo-1,4-benzoquinone; n = 4: SMe2L = 3,6-bis(dimethylsulfonium)-2,5-dihydroxo-1,4-benzoquinone diylide) and their one-electron-reduced analogues. Variable-temperature dc magnetic susceptibility data reveal the presence of weak ferromagnetic superexchange between FeII centers in the oxidized species, with exchange constants of J = +1.2(2) (R = OMe, Cl) and +0.3(1) (R = NO2, SMe2) cm-1. In contrast, X-ray diffraction, cyclic voltammetry, and Mössbauer spectroscopy establish a ligand-centered radical in the reduced complexes. Magnetic measurements for the radical-bridged species reveal the presence of strong antiferromagnetic metal-radical coupling, with J = -57(10), -60(7), -58(6), and -65(8) cm-1 for R = OMe, Cl, NO2, and SMe2, respectively. The minimal effects of substituents in the 3- and 6-positions of RLx-• on the magnetic coupling strength is understood through electronic structure calculations, which show negligible spin density on the substituents and associated C atoms of the ring. Finally, the radical-bridged complexes are single-molecule magnets, with relaxation barriers of Ueff = 50(1), 41(1), 38(1), and 33(1) cm-1 for R = OMe, Cl, NO2, and SMe2, respectively. Taken together, these results provide the first examination of how bridging ligand substitution influences magnetic coupling in semiquinoid-bridged compounds, and they establish design criteria for the synthesis of semiquinoid-based molecules and materials.