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Bioprocess optimization towards higher productivity and better quality control relies on real-time process monitoring tools to measure process and culture parameters. Cell concentration and viability are among the most important parameters to be monitored during bioreactor operations that are typically determined using optical methods on an extracted sample. In this paper, we have developed an online non-invasive sensor to measure cell concentration and viability based on Doppler ultrasound. An ultrasound transducer is mounted outside the bioreactor vessel and emits a high frequency tone burst (15 MHz) through the vessel wall. Acoustic backscatter from cells in the bioreactor depends on cell concentration and viability. The backscattered signal is collected through the same transducer and analyzed using multivariate data analysis (MVDA) to characterize and predict the cell culture properties. We have developed accurate MVDA models to predict the Chinese hamster ovary (CHO) cell concentration in a broad range from 0.1 × 10

Black Ti (bTi) surfaces comprising high aspect ratio nanopillars exhibit a rare combination of bactericidal and osteogenic properties, framing them as cell-instructive meta-biomaterials. Despite the existing data indicating that bTi surfaces induce osteogenic differentiation in cells, the mechanisms by which this response is regulated are not fully understood. Here, we hypothesized that high aspect ratio bTi nanopillars regulate cell adhesion, contractility, and nuclear translocation of transcriptional factors, thereby inducing an osteogenic response in the cells. Upon the observation of significant changes in the morphological characteristics, nuclear localization of Yes-associated protein (YAP), and Runt-related transcription factor 2 (Runx2) expression in the human bone marrow-derived mesenchymal stem cells (hMSCs), we inhibited focal adhesion kinase (FAK), Rho-associated protein kinase (ROCK), and YAP in separate experiments to elucidate their effects on the subsequent expression of Runx2. Our findings indicated that the increased expression of Runx2 in the cells residing on the bTi nanopillars compared to the flat Ti is highly dependent on the activity of FAK and ROCK. A mechanotransduction pathway is then postulated in which the FAK-dependent adhesion of cells to the extreme topography of the surface is in close relation with ROCK to increase the endogenous forces within the cells, eventually determining the cell shape and area. The nuclear translocation of YAP may also enhance in response to the changes in cell shape and area, resulting in the translation of mechanical stimuli to biochemical factors such as Runx2.

Folding nanopatterned flat sheets into complex 3D structures enables the fabrication of meta-biomaterials that combine a rationally designed 3D architecture with nanoscale surface features. Self-folding is an attractive approach for realizing such materials. However, self-folded lattices are generally too compliant as there is an inherent competition between ease-of-folding requirements and final load-bearing characteristics. Inspired by sheet metal forming, an alternative route is proposed for the fabrication of origamilattices. This ‘automated-folding’ approach allows for the introduction of sharp folds into thick metal sheets, thereby enhancing their stiffness. The first time realization of automatically folded origami lattices with bone-mimicking mechanical properties is demonstrated. The proposed approach is highly scalable given that the unit cells making up the meta-biomaterial can be arbitrarily large in number and small in dimensions. To demonstrate the scalability and versatility of the proposed approach, it is fabricated origamilattices with > 100 unit cells, lattices with unit cells as small as 1.25 mm, and auxetic lattices. The nanopatterned the surface of the sheets prior to folding. Protected by a thin coating layer, these nanoscale features remained intact during the folding process. It is found that the nanopatterned folded specimens exhibits significantly increased mineralization as compared to their non-patterned counterparts.

Placement of shallow foundations near or adjacent to slopes reduces their seismic and static bearing capacities. In this paper, the seismic behavior of shallow foundations adjacent to sandy slopes has been studied using a two-dimensional finite element method. Most of the previous studies have focused on upper bound solutions in limit state analysis framework via pseudo-static loading, and the effects of actual seismic loading such as loading frequency effects, acceleration amplitude above 0.30 g, non-linear dynamic analysis, and so on are ignored. The shallow foundations are located at a certain distance from the slope crest (i.e., d = 0.5b, 1.5b and 2.0b). The slope inclination angle studied in this paper is 25° (1 V: 2 H). The analyzed slope is composed of medium dense sand. The two elastic–perfectly plastic Mohr–Coulomb (MC) and hardening soil (HSM) constitutive models have been considered to investigate the effect of plastic behavior of the sandy soil. Innovatively, the actual seismic behavior of the slope, shallow foundation and the direction of the seismic responses have been studied. The results show that the structural and geotechnical responses of the HSM model are in most cases up to 30% larger and more conservative than the MC model responses. This shows the importance of using the HSM model in the study of seismic stability of slope and foundation.

The present study aims to investigate the variation of mechanical properties of clayey sand treated with cement and nano titanium dioxide (NTD). For this purpose, unconfined compression and direct shear tests were performed on mixtures of clayey sand treated with cement and NTD. To improve the number of experiments, examine the results, and optimize the content of NTD and the content of cement mixed with the clayey sand, the Response Surface Method (RSM) was used. Furthermore, the effect of NTD on the mixtures was investigated by conducting the element analysis along with field emission scanning electron microscopy (FESEM). The contents of Portland cement type I, NTD, and kaolinite clay were three independent variables in the mixtures. An empirical quadratic polynomial regression equation was suggested for predicting the results. The results obtained from reviewing the FESEM images revealed that NTD filled the holes and micro-cracks of the cemented clayey sand. In addition, the nucleating effect of NTD could reduce the orientation degree of calcium hydroxide (CH) and limit the CH value by absorbing the hydration products, water, and ions. Furthermore, the nucleating effect of NTD increased with time. In addition, an efficient optimized mixture was obtained for a mixture containing 1.48% NTD, 6.04% cement, and 20% Kaolinite. The cohesion, friction angle, and unconfined compression strength of the optimized mixture were 215.3 kPa, 49.78°, and 1.503 MPa, respectively.

espanolLa Guadua angustifolia Kunth (GAK) es una bamboo nativo del continente americano con gran adaptabilidad ecologica. Su composicion y estructura la convierte en una fuente lignocelulosica de buenas propiedades mecanicas. En este trabajo, fibras de GAK fueron pre-tratadas alcalinamente, mediante pulpeo Kraft a baja temperatura, se fijo un valor de alcali efectivo del 10% combinado con tres valores de sulfidez 10%, 15% y 30%. Se evaluaron los cambios en la superficie de la fibra y el valor en la retencion de agua despues de los tratamientos alcalinos. Con una porcion en masa del 5% de fibras pre-tratadas se fabricaron tableros de cemento reforzados y se evaluo los efectos de la concentracion de la sulfidez del tratamiento alcalino en las propiedades fisico-mecanicas de los tableros. Los tableros de cemento reforzados con fibras fueron evaluados mecanicamente a los 7, 28 y 180 dias de fraguado. Los resultados mostraron que la resistencia a la flexion en tableros reforzados con fibras tratadas es mayor que en tableros reforzados con fibras no tratadas. Despues de 180 dias de fraguado no se observo reduccion de la resistencia a flexion lo que indica que los tratamientos alcalinos evitaron la degradacion de las fibras en la matriz de cemento. Finalmente, los resultados mostraron que un valor menor en la sulfidez (10%) conduce a fibras con superficies mas limpias mejorando la adherencia en la matriz fibra-cemento y produciendo tableros compuestos de cemento y G. angustifolia Kunth con mayor desempeno mecanico. EnglishGuadua angustifolia KUNTH is a giant grass native to America with high ecological adaptability. Its composition and structure make it in a lignocellulosic source with good mechanical properties with wide applications. Guadua angustifolia fibers were alkali pretreated by Kraft pulping at low temperatures. An amount of 10% of active alkali was combined with three different sulphide levels -10% -15%, and 30%. A mass portion of 5% of pretreated fibers was used to reinforce the fiber cement board composites produced by the slurry method. The effects of sulfidity concentration in treatment over the physical-mechanical properties of fiber cement board composites were evaluated. Superficial changes on Guadua fiber and water retention value after alkaline treatments were determined. Fiber cement boards were mechanically tested after 7, 28, and 180 days of curing. Results showed flexural strength in boards reinforced with treatedfibers is greater than flexural strength in boards reinforced with untreatedfibers; moreover, after 180 days of curing, there was no flexural strength reduction, indicating that alkaline treatments avoid fiber degradation into the cement matrix. Finally, results showed that low sulfidity concentration (10%) produces fibers with cleaner surfaces, improving fiber-cement bonding, and these fibers allowed the production of fiber cement boards with higher flexural strength.

Machine-matter, of which mechanical metamaterials and meta-devices are important sub-categories, is emerging as a major paradigm for designing advanced functional materials. Various exciting applications of these concepts have been recently demonstrated, ranging from exotic mechanical properties to device-like and adaptive functionalities. The vast majority of the studies published to date have, however, focused on the quasi-static behavior of such devices, neglecting their rich dynamic behavior. Recently, we proposed a new class of strain rate-dependent mechanical metamaterials that are made from bi-beams (i.e., viscoelastic bilayer beams). The buckling direction of such bi-beams can be controlled with the applied strain rate. The proposed approach, however, suffers from a major limitation: 3D printing of such bi-beams with such a 'strong' differential strain rate-dependent response is very challenging. Here, we propose an alternative approach that only requires a 'weak' differential response and a rationally designed geometric artifact to control the buckling direction of bi-beams. We present an analytical model that describes the landscape of all possible combinations of geometric designs and hyperelastic as well as viscoelastic properties that lead to the desired strain rate-dependent switching of the buckling direction. We also demonstrate how multi- and single-material 3D printing techniques can be used to fabricate the proposed bi-beams with microscale and submicron resolutions. More importantly, we show how the requirement for a weak differential response eliminates the need for multi-material 3D printing, as the change in the laser processing parameters is sufficient to achieve effective differential responses. Finally, we use the same 3D printing techniques to produce strain rate-dependent gripper mechanisms as showcases of potential applications.

In this research a series of experimental tests were performed to investigate the effects of nano TiO2 (NT) on the triaxial behavior of cemented clayey sand (with variable amounts of kaolinite). To reduce the number of experiments, time and cost of research, the design and assessment of the experiments were performed using the response surface method (RSM). The amount of used NT was 0-4 wt% of cement, and the amounts of cement and kaolinite were 3-9 wt% and 10-30 wt% of soil respectively. The consolidated drained (CD) triaxial tests were performed for the confining pressures of 100, 300 and 600 kPa. The results of these tests showed that the amount of kaolinite clay at 20 % has the largest effect on the peak deviator stress and friction angle, but the soil cohesion has an ascending trend at 10-30 % kaolinite clay. The amount of cement in the range of 3-9 % causes an increase in the peak-deviator stress, shear strength parameters and the brittleness index. Also, the use of NT in a desirable amount (2 %) causes an increase in the peak deviator stress and the shear strength parameters.

This research investigates the impact of mix design methods on the mechanical characteristics of steel fibre-reinforced concrete (SFRC) made with recycled aggregates (RA) obtained from a precast waste concrete. The experimental campaign was carried out in two phases. In phase I, three types of steel fibre (SF) differing only in shape were examined. Then, eight mixes were formulated, considering a range of SF volume ratios from 0.125% to 1.5%, using both normal and the Equivalent mortar volume (EMV) mix design methods. In phase II, a reference mix and two recycled aggregate concrete mixes were developed, one designed with normal method and the other with the EMV technique and incorporating their associated optimum SF content obtained in phase I. The results show that the mechanical properties of SFRC proportioned with the EMV approach is not adversely affected and that water absorption capacity of the concrete is improved with this method compared to the traditional method. Also, mix design method adopted for recycled concrete affects the optimum SF volume ratio.

This research provides two probabilistic and deterministic methods to assess the liquefaction potential based on the piezocone (CPTu), and then a procedure is proposed to develop the seismic fragility curves of soil liquefaction. For this purpose, a reliable liquefaction case history dataset based on CPT and CPTu tests is compiled. Next, a deterministic correlation of the liquefaction potential is proposed by the use of the Group Method of Data Handling type neural network optimized with genetic algorithms. Data mining techniques are then used to compare the results of the various models, including the proposed deterministic model. The results demonstrate that an improvement in statistical measures of performance of the proposed model has been achieved. Through this study, a sensitivity analysis is carried out to clarify the more properties of the proposed method. Finally, a new probabilistic function is expanded based on the results of the deterministic approach. The developed probabilistic function is utilized as a proper tool to evaluate the fragility curves of liquefaction occurrence.

The assessment of the strength parameters of geological formations in regional scale which encounters thousands of slopes is a complicated approach and time consuming and needs huge field work. This issue is an important research topic concerning the regional seismic-landslide susceptibility analysis or hazard zonation. An empirical regression model was presented to estimate the Geological Strength Index (GSI) with an implication on geological quadrangle of Gorgan region at Alborz mountains range (north of Iran). Two main sets of data were applied in this study: (1) geomorphological data including the slope height, aspect, and distance from faults and distance from thrusts and (2) the physical and mechanical properties of rocks including the unit weight, uniaxial compressive strength (σci), and the petrographic constant (mί) of intact rock. The first group was extracted from a 1 : 100,000 digital geologic map and 10 m digital elevation model (DEM) and the second group was obtained from the Hoek–Brown failure criterion recommended tables. Linear regression equations were generated applying data collected from 294 studied stations using SPSS software. The regression equation predicted GSI in terms of (1) the distance from faults, (2) the distance from thrusts, and (3) the uniaxial compressive strength (σci). The equation had an R2 value of 0.739 and thus fit well to the data. The new method in its present state was recommended for the estimation of the GSI values in regional scale conditions for the assessment of landslide susceptibility and hazard mapping or post events landslide occurrence prediction in the case of probable big earthquakes in Alborz area that is required for emergency responses. The results indicated that the estimation error was about ±30 while the average error was within +5 and −5 and average error percentage was about 3%.

Recurrent bacterial infection is one of the main reasons of implant failure, hugely impacting the patients’ quality of life, and ultimately resulting in morbidity and even mortality. This type of infection starts with the attachment of the bacteria to the implant surface, leading to biofilm formation and, thus, high resistance against antibacterial agents. To date, numerous strategies have been proposed to prevent biofilm formation and implant-associated infections. It has been revealed that physical surface patterns with specific dimensions and mechanical properties may have the potential to kill implant associated bacteria through a mechanical mechanism, while regulating stem cell differentiation. Therefore, the aim of this research was to advance the development of the nanofabrication methods for generation of patterns with controlled geometrical and mechanical characteristics, and assess their potential for achieving a dual surface biofunctionality for bone implants, namely osteogenic and bactericidal effects. The focus was on submicron to nanoscale patterns generated on 2D and 3D surfaces...

We designed and fabricated a simple setup for the controlled crumpling of nanopatterned, surface-porous flat metallic sheets for the fabrication of volume-porous biomaterials and showed that crumpling can be considered as an efficient alternative to origami-inspired folding. Before crumpling, laser cutting was used to introduce pores to the sheets. We then fabricated titanium (Ti) nanopatterns through reactive ion etching on the polished Ti sheets. Thereafter, nanopatterned porous Ti sheets were crumpled at two deformation velocities (i.e., 2 and 100 mm/min). The compression tests of the scaffolds indicated that the elastic modulus of the specimens vary in the range of 11.8–13.9 MPa. Micro-computed tomography scans and computational simulations of crumpled scaffolds were performed to study the morphological properties of the resulting meta-biomaterials. The porosity and pore size of the scaffolds remained within the range of those reported for trabecular bone. Finally, the in vitro cell preosteoblasts culture demonstrated the cytocompatibility of the nanopatterned scaffolds. Moreover, the aspect ratio of the cells residing on the nanopatterned surfaces was found to be significantly higher than those cultured on the control scaffolds, indicating that the nanopatterned surface may have a higher potential for inducing the osteogenic differentiation of the preosteoblasts.

La necesidad de materiales de construcción sostenible, respetuosa con el medio ambiente y eficiente energéticamente justifican el interés en el desarrollo de materiales compuestos de cemento reforzados con fibras de Guadua Angustifolia Kunth. Esta planta se caracteriza por sus buenas propiedades mecánicas mostrando una alta resistencia a la flexión y la compresión, por lo que es conocida como el acero vegetal. Si bien la guadua como material completo es utilizado en diferentes regiones del país para la construcción de viviendas, pocos estudios se han desarrollado para el uso de sus fibras. En esta investigación, fibras de Guadua Angustifolia Kunth obtenidas después de un tratamiento alcalino se emplearon como refuerzo en la producción de tableros compuestos de cemento. El tratamiento alcalino tuvo tres niveles diferentes de cocción 1, 2 y 3 horas. Se fabricaron 9 probetas por el método de vaciado con cada uno de los niveles de tratamiento, además la evaluación de las propiedades mecánicas se realizó a los 7, 28 y 180 días de curado. La variación estructural de banda asociadas a carbohidratos estructurales de las fibras debido al tratamiento y la respuesta a la flexión de los tableros a los 7, 28 y 180 días de curado fue evaluada. Se pudo observar que el tratamiento con hidróxido de calcio reduce el contenido de compuestos no celulósicos y la inclusión de estas fibras como refuerzo en tableros de cemento genera materiales con propiedades mecánicas adecuadas para su uso en aplicaciones de construcción no estructural.

To assess the distribution of Mayaro virus (MAYV) in Latin America and the Caribbean and evaluate existing country-level MAYV surveillance mechanisms.Research was conducted from May 2018 through May 2019 to collect data from academic literature on Mayaro fever in Latin America and the Caribbean. PubMed, ClinicalKey, Scopus, Nature, SciELO, LILACS, and Google Scholar were searched for peer-reviewed journal articles, and data from health authorities, including the Pan American Health Organization (PAHO) and ministries of health, was also sought. MAYV-related publications published from 1954 through 2019 were screened. Publications that added to the overall understanding of MAYV, including its geographical and epidemiological distribution, were included in this report.A total of 901 MAYV cases have been reported in humans in countries in Latin America and the Caribbean. Since its discovery in 1954 in Trinidad and Tobago, MAYV has been isolated from individuals living in Argentina, Bolivia, Brazil, Ecuador, French Guiana, Haiti, Mexico, Panama, Peru, and Venezuela. Of those 901 cases, 42 of them were reported exclusively by health authorities. In contrast, 843 confirmed and presumptive autochthonous cases and an additional 16 imported cases were identified in academic literature. No country-level surveillance mechanisms for MAYV were recorded in academic literature or by health authorities.This report demonstrates that MAYV surveillance efforts are limited in comparison to the virus's presence in Latin America and the Caribbean, highlighting the importance of enhancing arboviral surveillance systems in the affected countries.Evaluar la distribución del virus Mayaro (MAYV) en América Latina y el Caribe y los mecanismos de vigilancia de nivel nacional.Entre mayo de 2018 y mayo de 2019 se llevó a cabo una revisión bibliográfica sobre la fiebre de Mayaro en América Latina y el Caribe en las bases de datos PubMed, ClinicalKey, Scopus, Nature, SciELO, LILACS y Google Académico para identificar artículos en revistas arbitradas; también se revisó información suministrada por las autoridades sanitarias, entre ellas la Organización Panamericana de la Salud y los ministerios de salud. Se revisaron artículos relacionados con MAYV publicados entre 1954 y 2019. En este informe se incluyeron artículos que contribuyeran a la comprensión general sobre el MAYV, incluida su distribución geográfica y su epidemiología.Se han reportado 901 casos de MAYV en seres humanos en 11 países de América Latina y el Caribe. Desde su descubrimiento en 1954 en Trinidad y Tobago, MAYV ha sido aislado de personas en Argentina, Bolivia, Brasil, Ecuador, Guayana Francesa, Haití, México, Panamá, Perú y Venezuela. De estos 901 casos, 42 fueron reportados exclusivamente por las autoridades sanitarias. A la vez, en la bibliografía se identificaron 844 casos autóctonos confirmados o presuntivos y 15 casos importados. A través de la bibliografía o las autoridades sanitarias no se identificaron mecanismos de vigilancia de nivel nacional para el MAYV.En América Latina y el Caribe la vigilancia del MAYV es limitada en comparación con la presencia del virus en la región; es necesario mejorar los sistemas de vigilancia de arbovirus en los países afectados.Analisar a distribuição do vírus Mayaro (MAYV) na América Latina e Caribe e avaliar os mecanismos nacionais de vigilância.Dados da literatura acadêmica sobre a febre Mayaro na América Latina e Caribe foram coletados de maio de 2018 a maio de 2019. Foram pesquisadas as bases de dados PubMed, ClinicalKey, Scopus, Nature, SciELO, LILACS e Google Acadêmico para identificar artigos em revistas revisadas por pares; também foram examinados dados de autoridades sanitárias, incluindo a Organização Pan-Americana da Saúde (OPAS), e dos ministérios de saúde. Artigos relacionados com MAYV publicados de 1954 a 2019 foram revisados. Este relatório incluiu artigos que contribuíssem para o entendimento geral do MAYV, com informações sobre distribuição geográfica e epidemiologia.Foram registrados 901 casos de MAYV em humanos em 11 países da América Latina e do Caribe. Desde a sua descoberta em 1954 em Trinidad e Tobago, o MAYV foi isolado em indivíduos na Argentina, Bolívia, Brasil, Equador, Guiana Francesa, Haiti, México, Panamá, Peru e Venezuela. Desses 901 casos, 42 foram comunicados exclusivamente pelas autoridades sanitárias. Por sua vez, 844 casos autóctones confirmados ou suspeitos e 15 casos importados foram descritos na literatura. Nenhum mecanismo nacional de vigilância do MAYV foi identificado na literatura ou pelas autoridades sanitárias.Na América Latina e Caribe, a vigilância do MAYV é limitada em contraste com a presença do vírus na região; é importante melhorar os sistemas de vigilância desse arbovírus nos países afetados.

In this paper, an investigation aimed at characterising the behaviour of headed shear studs in push-out testing is presented. The study aims to contribute to the limited knowledge of Pultruded Fibre Reinforced Polymer (PFRP)-concrete composites, highlighting the predominant failure mode and the underlying variables relevant for predictive analytical equations. Two phases of experimental push-out tests were carried out on composite slabs comprising of normal density concrete (NWC), and PFRP connected using steel headed studs. Phase one focused on studying the effects of headed shear stud configuration on the load capacity of the composite slabs, adopting 19 mm diameter studs. Phase two of the study was aimed at characterising the behaviour of the composite slab by varying the headed stud diameters. Two push-out test specimens adopted 12 mm diameter studs, and a third specimen within this phase adopted the 16 mm stud diameter. The dominant failure mode was bearing, net tension and shear out failures of the FRP plates. These modes of failure were distinctly different from those prevalent in the conventional steel-concrete composite, which is either stud shank failure or concrete pull out. The test investigation suggested a successive increase in shear capacity with increased stud sizes. Specimen with stud size of 16 mm attained higher shear strength per stud, approximately 29.4% in comparison to those with 12 mm diameter studs. The study observed that PFRP-concrete composites could mobilise between 40 and 50% shear resistances to that of their steel-concrete counterpart’s. However, the intensity of bearing failure increases with increase in stud size, thereby compromising the ductility of shear connection.

The effects of specimen disturbance on determining of various soil properties are one of the most challenging issues in geotechnical engineering. Types of disturbance mechanisms were generated in consolidation test. One of the important parameters in computing of consolidation settlement is the compression index (Cc). So that the effects of disturbance in the soil specimen reduced the amount of this parameter and could have a significant effect on the settlement calculations. Main propose of this study is evaluation of disturbance effects on Cc with using shear wave velocity. Study area was Tabriz in located in the northwest of Iran with different silty and type of clayey soils such as yellow, green, and gray marls have a significant consolidation potential. In this research, three boreholes drilled and twenty intacy samples obtained. Also, Shear wave velocity in field and laboratory was determined respectively with performing down hole and bender element (in situ effective confining stress) tests. In continue, the quality of all specimens were evaluated by five recent methods. Then, the correlation between the common specimen evaluation methods new process based on shear wave velocity values with the calculation of statistical coefficients were computed. Results showed that, shear wave velocity values before and after consolidation with in situ effective stress could a new evaluation criterion provide for the definition of sample quality (Q). Also, the compression index as well as pre-consolidation pressure for disturbance effects were corrected by the estimation of the disturbance percent using shear wave velocity.

The present study investigates the effect of blend copolymers on the physico-mechanical properties of mortar mixes. Blend copolymers were synthesized based on poly vinyl alcohol (PVA) and urea (U) in aqueous solution with different blend ratios 65/35, 50/50 and 35/65 respectively, using glacial acetic acid as crosslinking. Physico-mechanical properties of mortar examined included water/cement ratio, setting time, workability, water absorption and compressive strength. The addition of blend copolymers to the mortar affected the physico-mechanical properties of mortar mixes. As the content of PVA increases in the blend copolymers, the water of consistency decrease, whereas the setting times (initial & final) were shortened. The compressive strength of the hardened cement pastes was increased at all ages of hydration while water absorption decreased.

One of the major problems with the bone implant surfaces after surgery is the competition of host and bacterial cells to adhere to the implant surfaces. To keep the implants safe against implant-associated infections, the implant surface may be decorated with bactericidal nanostructures. Therefore, fabrication of nanostructures on biomaterials is of growing interest. Here, we systematically studied the effects of different processing parameters of inductively coupled plasma reactive ion etching (ICP RIE) on the Ti nanostructures. The resultant Ti surfaces were characterized by using scanning electron microscopy and contact angle measurements. The specimens etched using different chamber pressures were chosen for measurement of the mechanical properties using nanoindentation. The etched surfaces revealed various morphologies, from flat porous structures to relatively rough surfaces consisting of nanopillars with diameters between 26.4 ± 7.0 nm and 76.0 ± 24.4 nm and lengths between 0.5 ± 0.1 μm and 5.2 ± 0.3 μm. The wettability of the surfaces widely varied in the entire range of hydrophilicity. The structures obtained at higher chamber pressure showed enhanced mechanical properties. The bactericidal behavior of selected surfaces was assessed against Staphylococcus aureus and Escherichia coli bacteria while their cytocompatibility was evaluated with murine preosteoblasts. The findings indicated the potential of such ICP RIE Ti structures to incorporate both bactericidal and osteogenic activity, and pointed out that optimization of the process conditions is essential to maximize these biofunctionalities.

In onshore and offshore fields of ocean engineering, piles are used as foundation systems for various structures. Piles are classified into different types depending on their materials, geometries,...

Purpose This paper aims to review the effect of using recycled aggregates (RA) on the properties of recycled aggregate concrete (RAC) following the steady rise in global demand for concrete and the large generation of construction and demolition waste. Design/methodology/approach This study reviewed relevant literature of research work carried out by previous researchers, leading to a deeper understanding of the properties of both RA and RAC. The properties of RA and RAC reported in the various studies were then compared to their corresponding natural aggregate (NA) and natural aggregate concrete, as well as the specifications provided in different codes of practice. In addition, the mix design methods appropriate to RAC and the cost implication of using RA were reviewed. Findings Findings show that the contribution of RA to strength appears inferior in comparison to NA. The shortcoming is attributed to the mortar attached to the RA, which raises its water absorption capacity and lowers its density relative to those of NA. However, it has been reported that the use of regulated quantity of RA, new mixing and proportioning methods, the addition of admixtures and strengthening materials such as steel fibres, can improve both mechanical and durability properties of RAC. Cost evaluation also showed that some savings can be realized by using RA instead of NA. Originality/value This research serves as a guide for future works and suggests that the use of RA as aggregate in new concrete is technically possible, depending on the mix design method adopted.

ICCP system provides effective corrosion protection in a chloride environment. This research evaluates the feasibility of zinc rich paints (ZRP) as ICCP anode for RC structures. The preliminary investigation showed the application of three layers of ZRP with medium concrete surface roughness and use of Cu/Nb/Pt wire as primary anode gives maximum bond strength and uniform current distribution across the ZRP coating. Moreover, polarization results showed satisfactory performance of the ZRP anode coating subjected to a current density of 12.5 mA/m2. The anode was found to be vapour permeable and effectively provide protection with a service life of up to 15 years.

After the liquefaction of sand, the prediction of anisotropy and heterogeneity is one of the complexities of constitutive law. This study aimed to develop a method to more effectively assess anisotropy and strain and stress distributions, and determine their history in cohesionless soil. To achieve this objective, instead of defining all the direction-dependent events on the three orthogonal planes of the Cartesian coordinate system, numerical integration was utilized to make use of 17 planes with pre-defined directions. This leads to a more accurate and powerful assessment of anisotropy and its effects. The constitutive equations of the proposed model were adjusted with a multilaminate framework, and its result for different monotonic and cyclic loading, drained and undrained conditions, and different pressures and void ratios were verified using the experimental data. Finally, the model's performance in predicting induced anisotropy is demonstrated under cyclic mobility conditions on the 17 planes.

This paper presents a study on the stochastic bearing capacity of two parallel strip footings supported on a heterogeneous sand layer confined by a rigid base. Variability of the sand is represented by a truncated normal distribution function of its friction angle to produce a geostatistical equivalent to the deterministic bearing capacity. A method was first demonstrated to derive an analytical distribution function of the bearing capacity for a single surface footing with a rigid base layer for which an exact bearing capacity function is available. For the twin foundation problem with no explicit deterministic solutions, a Monte Carlo simulation was adopted. The stochastic bearing capacity relative to its deterministic equivalent was determined for a set of layer thicknesses and footing distances in terms of the assumed geostatistical characteristics of the sand and resulting bearing capacity distributions. The Monte Carlo methodology is adaptable in design to model other bearing capacity problems with more complex and random soil distributions.

The injection of carbon dioxide (CO2) captured from combustion-based processes into underground formations is one of a number of plausible methods to reduce its release into the atmosphere and consequential greenhouse gas warming. Once the gas has been captured efficiently and effectively, depleted oil and gas reservoirs are seen as high potential candidates for carbon storage projects. However, legacy issues associated with a high number of oil and gas wells abandoned during the last few decades put the carbon capture and storage projects (CCS) at risk. These include any defects within the cement surrounding the well casing or for capping an abandoned well that can become unwanted CO2 leakage pathways. To predict the lifespan of these cements due to exposure to CO2-bearing fluids at the conditions found underground, the geochemical processes need to be coupled with the geomechanical changes within the cement matrix. In a viable CCS project for sequestering CO2, the cement matrix should be capable of withstanding acidic environments formed by dissolution of CO2 in brine for more than ten thousand years. This work aims at providing a framework to predict the behaviour of cement due to CO2 exposure under reservoir conditions. The results show that the chemical reactions and geomechanical changes within the cement matrix can result either in its radial cracking or radial compaction. Both of these behaviours are investigated as possible phenomena which may affect the CO2 leakage, and therefore the viability of the site for long term carbon storage.

The presence of a rigid layer underlying a soil bed layer supporting twin footings affects the footing bearing capacity and settlement. In this study, the bearing capacity and settlement of twin large-scale circular footings on unreinforced and geocell-reinforced sand layers with various thicknesses are investigated. The role of layer thickness, distance between two adjacent footings, and footing diameter indicates that the rigid base substantially influences the footing bearing pressure, settlement and tilt. The results show that the maximum bearing capacity is achieved when two footings are in contact and the rigid base is at shallow depth. The influence of the footing interference on settlement and tilting of closely spaced footings at a given load decreases with decreasing depth of rigid base and reinforcing the sand with geocells. This is observed for rigid bases located at less than about 2B, where B is the footing diameter.

Developing high-throughput nanopatterning techniques that also allow for precise control over the dimensions of the fabricated features is essential for the study of cell-nanopattern interactions. Here, we developed a process that fulfills both of these criteria. Firstly, we used electron-beam lithography (EBL) to fabricate precisely controlled arrays of submicron pillars with varying values of interspacing on a large area of fused silica. Two types of etching procedures with two different systems were developed to etch the fused silica and create the final desired height. We then studied the interactions of preosteoblasts (MC3T3-E1) with these pillars. Varying interspacing was observed to significantly affect the morphological characteristics of the cell, the organization of actin fibers, and the formation of focal adhesions. The expression of osteopontin (OPN) significantly increased on the patterns, indicating the potential of the pillars for inducing osteogenic differentiation. The EBL pillars were thereafter used as master molds in two subsequent processing steps, namely soft lithography and thermal nanoimprint lithography for high-fidelity replication of the pillars on the substrates of interest. The molding parameters were optimized to maximize the fidelity of the generated patterns and minimize the wear and tear of the master mold. Comparing the replicated feature with those present on the original mold confirmed that the geometry and dimensions of the replicated pillars closely resemble those of the original ones. The method proposed in this study, therefore, enables the precise fabrication of submicron- and nanopatterns on a wide variety of materials that are relevant for systematic cell studies. Statement of significance: Submicron pillars with specific dimensions on the bone implants have been proven to be effective in controlling cell behaviors. Nowadays, numerous methods have been proposed to produce bio-instructive submicron-topographies. However, most of these techniques are suffering from being low-throughput, low-precision, and expensive. Here, we developed a high-throughput nanopatterning technique that allows for control over the dimensions of the features for the study of cell-nanotopography interactions. Assessing the adaptation of preosteoblast cells showed the potential of the pillars for inducing osteogenic differentiation. Afterward, the pillars were used for high-fidelity replication of the bio-instructive features on the substrates of interest. The results show the advantages of nanoimprint lithography as a unique technique for the patterning of large areas of bio-instructive surfaces.

Piles or deep foundations are elements for transferring the load of structures to the substructure and soil layers with more suitable conditions to guarantee the stability of the structure and provide proper service by them. In this regard, the driven and bored piles are commonly used, but high noise and vibration of the driven piles, as well as difficulties and limitations in implementation of the bored piles, have led to the use of a new alternative type of piles installed in the soil using torque and a small amount of compressive axial force. Helical and drilled displacement piles can be mentioned as new types of these piles. Considering the increasing use of these piles, still a few studies have been conducted on them and there is a need for further research on their behavior in different soils and conditions. Therefore, in the present study, in two field and experimental sections, behavior of these piles was evaluated by performing tensile and compressive loading tests. Three models of helical, Tsubasa, and drilled displacement pile were implemented and loaded in experimental section in the frustum-confining vessel of the Amirkabir University of Technology (FCV-AUT) and were compared with the previous works in field section. Our results revealed that drilled displacement pile had better performance than other piles under tension and compression, and it had harder behavior and better capacity than the other two piles in both experimental and field conditions. Also, the required torque of this pile had higher values ​​compared to other piles.

In modern society, the inherent differences found between females and males are a sensitive topic of debate. It is common for people to associate females with the possession of stronger and more profound visual and auditory memory in comparison to males. This research explored the variances between the sexes by examining and comparing the auditory and visual memories of a population of females and a population of males. The auditory and visual memories of the different sexes will be analyzed through a variety of tasks that will measure their memory capabilities. Participants of the experiment took two pre-designed tests, a different test for each type of memory. The auditory test included four distinct sounds that played in a specific pattern and challenged the participants’ memory capacities. Through the use of MATLAB, a program developed by MathWorks, and by using coding language, a visual memory game was developed for the visual test. This test contained four different colors that illuminated in a specific sequence. Each participant completed two trials for each type of test to allow them the opportunity to achieve their maximum potential. The analysis of the results contradicted stereotypical beliefs embedded in societal norms. Males collectively demonstrated a higher capacity for memory than females. Notably, both sexes improved their memory performance on the visual tests more than the auditory tests. An application of these results could be used as therapeutic exercises to help strengthen the memory of patients who suffer from Alzheimer’s disease and other memory loss.

Laboratory experiments were used to determine the suitability of raw industrial by-products obtained within the United Kingdom that are being taken to landfill sites and develop a hydraulic...

BACKGROUND There are limited data on coronavirus disease 2019 (COVID-19) in vaccinated patients with inflammatory bowel disease (IBD). We aimed to describe outcomes and identify risk factors for hospitalization, severe COVID-19, and death in this population. METHODS Data from the Surveillance Epidemiology of Coronavirus Under Research Exclusion in Inflammatory Bowel Disease (SECURE-IBD) database were analyzed. Patients with IBD who received at least one vaccine dose prior to diagnosis of COVID-19 were included. Patients received mRNA (Pfizer and Moderna), adenovirus vector (CanSino, AstraZeneca, Sputnik, and Janssen), or inactivated SARS-CoV-2 (Sinovac) vaccines. Partial vaccination was defined as having not received the full complement of doses for the vaccine received. Outcomes were hospitalization, death, and severe COVID-19, a composite of intensive care unit admission, mechanical ventilation, and/or death. RESULTS Among 141 cases, 12 (8.5%) were hospitalized, 4 (2.8%) had severe COVID-19, and 1 (0.7%) died. During the same period, proportions in the unvaccinated were 9.3%, 1.9%, and 1.2%, respectively. Nearly three-quarters of patients with COVID-19 after vaccination were on biologics and one-third were taking immunomodulators. Fewer hospitalizations occurred in those with completed vaccine series than partially complete series (5.7% vs 13.2%, p = 0.13), and in those receiving mRNA vaccines than adenovirus vector (4.7% vs 22.7%, p = 0.01) or inactivated SARS-CoV-2 (4.7% vs 16.7%, p=0.15) vaccines. Only 2.9% of those with completed mRNA series were hospitalized. Patients on biologic monotherapy were less frequently hospitalized than patients on immunomodulator monotherapy (4.2% vs 27.3%, p=0.03) or combination therapy (4.2% vs 10.0%, p = 0.36). Overall, hospitalized patients were older (mean age 50 years vs 40 years, p = 0.03). Severe COVID-19 was less common in those receiving mRNA vaccines than adenovirus vector (0.9% vs 4.6%; p = 0.31) or inactivated SARS-CoV-2 (0.9% vs 16.7%; p = 0.02) vaccines. Of the four patients with severe COVID-19, two were taking tumor necrosis factor antagonists, three were taking azathioprine, and one had chronic lung disease. The only death was in a patient on triple immunosuppression with adalimumab, azathioprine, and systemic steroids. CONCLUSION In patients with IBD, incomplete vaccination, non-mRNA vaccines, and immunomodulator use are associated with increased risk of adverse events during COVID-19 infections.

Performance of cathodic protection system in reinforced concrete structures is generally evaluated using 100 mV decay criterion. This approach is widely used, however has its own limitations. Recently, a new approach by determining the actual corrosion rate using the Butler Volmer equation has become an ‘alternative’ criterion for assessing the performance of cathodic protection system. This paper deals with critical examination and practical application of Butler-Volmer Equation to judge the effectiveness of cathodic protection system. Sensitivity analysis of various input parameters through numerical modelling by parametric studies showed significant dependence of corrosion rate on cathodic Tafel slope. One-year field data from a cathodic protection monitoring site in UK was collected and variability in the two approaches was assessed.

Despite the potential of small-scale pillars of black titanium (bTi) for killing the bacteria and directing the fate of stem cells, not much is known about the effects of the pillars’ design parameters on their biological properties. Here, three distinct bTi surfaces are designed and fabricated through dry etching of the titanium, each featuring different pillar designs. The interactions of the surfaces with MC3T3-E1 preosteoblast cells and Staphylococcus aureus bacteria are then investigated. Pillars with different heights and spatial organizations differently influence the morphological characteristics of the cells, including their spreading area, aspect ratio, nucleus area, and cytoskeletal organization. The preferential formation of focal adhesions (FAs) and their size variations also depend on the type of topography. When the pillars are neither fully separated nor extremely tall, the colocalization of actin fibers and FAs as well as an enhanced matrix mineralization are observed. However, the killing efficiency of these pillars against the bacteria is not as high as that of fully separated and tall pillars. This study provides a new perspective on the dual-functionality of bTi surfaces and elucidates how the surface design and fabrication parameters can be used to achieve a surface topography with balanced bactericidal and osteogenic properties.

Developing high-throughput nanopatterning techniques that also allow for precise control over the dimensions of the fabricated features is essential for the study of cell-nanopattern interactions. Here, we developed a process that fulfills both of these criteria. Firstly, we used electron-beam lithography (EBL) to fabricate precisely controlled arrays of high aspect ratio submicron pillars with varying values of interspacing on a large area (3 × 5 mm2) of fused silica substrates. Two types of etching procedures with two different systems were developed to etch the fused silica and create the final desired height. We then studied the interactions of preosteoblasts (MC3T3-E1) with these pillars. Varying interspacing was observed to significantly affect the morphological characteristics of the cell, the organization of actin fibers, and the formation of focal adhesions. The expression of osteopontin (OPN) significantly increased on the patterns, indicating the potential of the pillars for inducing osteogenic differentiation. The EBL arrays of pillars were thereafter used as master molds in two subsequent processing steps, namely soft lithography (using hybrid PDMS) and thermal nanoimprint lithography for high-fidelity replication of the pillars on the substrates of interest. The molding parameters were optimized to maximize the fidelity of the generated patterns and minimize the wear and tear of the master mold. Comparing the replicated feature with those present on the original mold confirmed that the geometry and dimensions of the replicated pillars closely resemble those of the original ones (i.e., 1% deviation in pillar interspacing, < 20% deviation in pillar diameter). The method proposed in this study, therefore, enables the precise fabrication of submicron- and nanopatterns on a wide variety of substrate materials that are relevant for systematic cell studies.

Micro- and nano-patterns are gaining increasing attraction in several fields ranging from nanoelectronics to bioengineering. The mechanical properties of the nanostructures (nanopillars, nanotubes, nanowires, etc.) are highly relevant for many applications but challenging to determine. Existing mechanical characterization methods require mounting the testing setup inside a scanning electron microscope (SEM) and additional sample modification. Here, we propose two atomic force microscopy (AFM) methods, based on contact mode imaging (CMI) and force spectroscopy imaging (FSI), to determine the mechanical characteristics of individual micro- and nanopillars as fabricated, without using SEM. We present the working principles of both methods and two case studies on nanopillars fabricated by additive manufacturing methods: two-photon polymerization (2PP) and electron beam induced deposition (EBID). Various mechanical parameters were determined using CMI and FSI, respectively. For the 2PP nanopillars, we measured the stiffness (13.5 ± 3.2 N/m and 15.9 ± 2.6 N/m), the maximum lateral force (883.0 ± 89.5 nN and 889.6 ± 113.6 nN), the maximum deflection (64.2 ± 13.6 nm and 58.3 ± 14.24 nm), the failure stress (0.3 ± 0.03 GPa and 0.3 ± 0.02 GPa), and the adhesion force (56.6 ± 4.5 µN and 58.6 ± 5.2 µN). For the EBID nanopillars, we measured the failure stress (2.9 ± 0.2 GPa and 2.7 ± 0.4 GPa). The similar results obtained using both techniques confirmed the efficacy and consistency of the methods. The proposed methodologies have the potential of enabling otherwise impossible measurements particularly when the specimens need to be tested under wet conditions, such as patterns for mechanobiological studies.