Characteristics and mechanisms of cadmium adsorption onto biogenic aragonite shells-derived biosorbent: Batch and column studies

© 2018 Elsevier Ltd Calcium carbonate (CaCO3)-enriched biomaterial derived from freshwater mussel shells (FMS) was used as a non-porous biosorbent to explore the characteristics and mechanisms of cadmium adsorption in aqueous solution. The adsorption mechanism was proposed by comparing the FMS properties before and after adsorption alongside various adsorption studies. The FMS biosorbent was characterized using nitrogen adsorption/desorption isotherm, X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, and point of zero charge. The results of batch experiments indicated that FMS possessed an excellent affinity to Cd(II) ions within solutions pH higher than 4.0. An increase in ionic strength resulted in a significant decrease in the amount of Cd(II) adsorbed onto FMS. Kinetic study demonstrated that the adsorption process quickly reached equilibrium at approximately 60 min. The FMS biosorbent exhibited the Langmuir maximum adsorption capacity as follows: 18.2 mg/g at 10 °C Cd2+ > Cu2+ > Cr3+ > Zn2+. For column experiments, the highest Thomas adsorption capacity (7.86 mg/g) was achieved at a flow rate (9 mL/min), initial Cd(II) concentration (10 mg/L), and bed height (5 cm). The Cd(II) removal by FMS was regarded as non-activated chemisorption that occurred very rapidly (even at a low temperature) with a low magnitude of activation energy. Primary adsorption mechanism was surface precipitation. Cadmium precipitated in the primary (Cd,Ca)CO3 form with a calcite-type structure on the FMS surface. A crust of rhombohedral crystals on the substrate was observed by SEM. Freshwater mussel shells have the potential as a renewable adsorbent to remove cadmium from water

Cr(VI) Removal from Aqueous Solution Using a Magnetite Snail Shell

© 2020, Springer Nature Switzerland AG. In this study, magnetic snail shell (MSS) prepared by impregnating of iron oxide onto snail shell (SS) powder was used for removing Cr(VI) from aqueous solution. Among six different mass ratios of Fe/SS powder studied, the MSS25 produced at a ratio of 25% achieved the highest Cr(VI) adsorption capacity. Batch adsorption experiments were conducted to investigate the adsorption isotherm, kinetics, and mechanism of Cr(VI) onto MSS25. The results illustrated that adsorption of Cr(VI) onto MSS25 reached equilibrium after 150 min at pH 3. The adsorption kinetics could be well described by the pseudo-second order model (R2 = 0.986). The Langmuir model (R2 = 0.971) was the best-fitting model that described the adsorption isotherm of Cr(VI) onto MSS25. The maximum adsorption capacity was 46.08 mg Cr(VI) per gram of MSS25. Ion exchange, electrostatic attraction, and adsorption-coupled reduction were determined as the main adsorption mechanisms of Cr(VI) onto MSS25. The high percentages of CaCO3 and Fe3O4 found in the MSS25 structure made a significant contribution to the Cr(VI) adsorption process

Phosphate Adsorption by Silver Nanoparticles-Loaded Activated Carbon derived from Tea Residue.

This study presents the removal of phosphate from aqueous solution using a new silver nanoparticles-loaded tea activated carbon (AgNPs-TAC) material. In order to reduce costs, the tea activated carbon was produced from tea residue. Batch adsorption experiments were conducted to evaluate the effects of impregnation ratio of AgNPs and TAC, pH solution, contact time, initial phosphate concentration and dose of AgNPs-AC on removing phosphate from aqueous solution. Results show that the best conditions for phosphate adsorption occurred at the impregnation ratio AgNPs/TAC of 3% w/w, pH 3, and contact time lasting 150 min. The maximum adsorption capacity of phosphate on AgNPs-TAC determined by the Langmuir model was 13.62 mg/g at an initial phosphate concentration of 30 mg/L. The adsorption isotherm of phosphate on AgNPs-TAC fits well with both the Langmuir and Sips models. The adsorption kinetics data were also described well by the pseudo-first-order and pseudo-second-order models with high correlation coefficients of 0.978 and 0.966, respectively. The adsorption process was controlled by chemisorption through complexes and ligand exchange mechanisms. This study suggests that AgNPs-TAC is a promising, low cost adsorbent for phosphate removal from aqueous solution

Nanofluids Research: Key Issues

Nanofluids are a new class of fluids engineered by dispersing nanometer-size structures (particles, fibers, tubes, droplets) in base fluids. The very essence of nanofluids research and development is to enhance fluid macroscopic and megascale properties such as thermal conductivity through manipulating microscopic physics (structures, properties and activities). Therefore, the success of nanofluid technology depends very much on how well we can address issues like effective means of microscale manipulation, interplays among physics at different scales and optimization of microscale physics for the optimal megascale properties. In this work, we take heat-conduction nanofluids as examples to review methodologies available to effectively tackle these key but difficult problems and identify the future research needs as well. The reviewed techniques include nanofluids synthesis through liquid-phase chemical reactions in continuous-flow microfluidic microreactors, scaling-up by the volume averaging and constructal design with the constructal theory. The identified areas of future research contain microfluidic nanofluids, thermal waves and constructal nanofluids

Contribution of a Common Variant in the Promoter of the 1-α-Hydroxylase Gene (CYP27B1) to Fracture Risk in the Elderly

CYP27B1 encodes mitochondrial 1α-hydroxylase, which converts 25-hydroxyvitamin D to its active 1,25-dihydroxylated metabolite. We tested the hypothesis that common variants in the CYP27B1 promoter are associated with fracture risk. The study was designed as a population-based genetic association study, which involved 153 men and 596 women aged 65–101 years, who had been followed for 2.2 years (range 0.1–5.5) between 1999 and 2006. During the follow-up period, the incidence of fragility fractures was ascertained. Bone ultrasound attenuation (BUA) was measured in all individuals, as were serum 25-hydroxyvitamin D and PTH concentrations; 86% subjects had vitamin D insufficiency. Genotypes were determined for the –1260C>A (rs10877012) and +2838T>C (rs4646536) CYP27B1 polymorphisms. A reporter gene assay was used to assess functional expression of the –1260C>A CYP27B1 variants. The association between genotypes and fracture risk was analyzed by Cox’s proportional hazards model. We found that genotypic distribution of CYP27B1 –1260 and CYP27B1 +2838 polymorphisms was consistent with the Hardy-Weinberg equilibrium law. The two polymorphisms were in high linkage disequilibrium, with D′ = 0.96 and r2 = 0.94. Each C allele of the CYP27B1 –1260 polymorphism was associated with increased risk of fracture (hazard ratio = 1.34, 95% CI 1.03–1.73), after adjustment for age, sex, number of falls, and BUA. In transient transfection studies, a reporter gene downstream of the –1260(A)-containing promoter was more highly expressed than that containing the C allele. These data suggest that a common but functional variation within the CYP27B1 promoter gene is associated with fracture risk in the elderly

Enhanced electrochemical reduction of hydrogen peroxide by Co3O4 nanowire electrode

Crystalline Co3O4 nanowire arrays with different morphologies grown on Ni foam were investigated by varying the reaction temperature, the concentration of precursors, and reaction time. The Co3O4 nanowires synthesized under typical reaction condition had a diameter range of approximately 500–900 nm with a length of 17 µm. Electrochemical reduction of hydrogen peroxide (H2O2) of the optimized Co3O4 nanowire electrode was studied by cyclic voltammetry. A high current density of 101.8 mA cm−2 was obtained at −0.4 V in a solution of 0.4 M H2O2 and 3.0 M NaOH at room temperature compared to 85.8 mA cm−2 at −0.35 V of the Co3O4 nanoparticle electrode. Results clearly indicated that the Ni foam supported Co3O4 nanowire electrode exhibited superior catalytic activity and mass transport kinetics for H2O2 electrochemical reduction

Does Applicability Domain Exist in Microarray-Based Genomic Research?

Constructing an accurate predictive model for clinical decision-making on the basis of a relatively small number of tumor samples with high-dimensional microarray data remains a very challenging problem. The validity of such models has been seriously questioned due to their failure in clinical validation using independent samples. Besides the statistical issues such as selection bias, some studies further implied the probable reason was improper sample selection that did not resemble the genomic space defined by the training population. Assuming that predictions would be more reliable for interpolation than extrapolation, we set to investigate the impact of applicability domain (AD) on model performance in microarray-based genomic research by evaluating and comparing model performance for samples with different extrapolation degrees. We found that the issue of applicability domain may not exist in microarray-based genomic research for clinical applications. Therefore, it is not practicable to improve model validity based on applicability domain

Multi-functional MIMO communication in multi-hop cellular systems

[EN] In the context of multi-hop cellular communications, user equipment devices (UEs) with relaying capabilities provide a virtual infrastructure that can enhance the cell spectral efficiency. UE relays, which are generally transparent to the destination user and lack channel state information, mainly operate in an open-loop mode. Most open-loop transmission techniques for relaying are based on orthogonal space-time block coding (OSTBC), which offers a good trade-off between performance and complexity. In this paper, we consider the concept of multi-functional multiple-input multiple-output (MIMO) transmission, which combines OSTBC with beamforming techniques. This concept is applied to networks with multiple relays, which can offer a high number of antennas to implement multi-functional MIMO techniques. The proposed schemes are shown to reduce the bit error rate of the destination user with respect to a direct transmission from the base station (BS). Furthermore, the multi-functional setup exhibits better performance than conventional OSTBC at high transmission rates.This work was performed in the framework of the FP7 project ICT-317669 METIS, which is partly funded by the European Union. The authors would like to acknowledge the contributions of their colleagues in METIS, although the views expressed are those of the authors and do not necessarily represent the project.Roger Varea, S.; Calabuig Soler, D.; Monserrat Del Río, JF.; Cardona Marcet, N. (2014). Multi-functional MIMO communication in multi-hop cellular systems. EURASIP Journal on Advances in Signal Processing. 2014(165):1-9. https://doi.org/10.1186/1687-6180-2014-165S192014165Timus B, Fallgren M (Eds): In D1.1: Scenarios, requirements and KPIs for 5G mobile and wireless system. Project deliverable, ICT-317669-METIS. 2013.Zheng K, Fan B, Ma Z, Liu G, Shen X, Wang W: Multihop cellular networks toward LTE-advanced. IEEE Veh. Tech. Mag 2009, 4(3):40-47.Gozalvez J, Coll-Perales B: Experimental evaluation of multihop cellular networks using mobile relays. IEEE Commun. Mag 2013, 51(7):122-129.Zhou B, Hu H, Huang S-Q, Chen H-H: Intracluster device-to-device relay algorithm with optimal resource utilization. IEEE Trans. Veh. Tech 2013, 62(5):2315-2326.Vanganuru K, Ferrante S, Sternberg G: System capacity and coverage of a cellular network with D2D mobile relays,. In Military Communications Conference,. Orlando (FL), USA; 2012:1-6. doi:10.1109/MILCOM.2012.6415659Bölcksei H, Nabar RU, Oyman O, Paulraj AJ: Capacity scaling laws in MIMO relay networks. IEEE Trans. Wireless Comm 2006, 5(6):1433-1444.Tarokh V, Jafarkhani H, Calderbank AR: Space-time block codes from orthogonal designs. IEEE Trans. Information Theory 1999, 45(5):1456-1467. 10.1109/18.771146Wang H, Xia XG: Upper bounds of rates of complex orthogonal space-time block codes. IEEE Trans. Information Theory 2003, 49(10):2788-2796. 10.1109/TIT.2003.817830Jafarkani H: A quasi-orthogonal space–time block code. IEEE Trans. Commun 2001, 49(1):1-4. 10.1109/26.898239Nguyen XH, Choi J: Joint design of groupwise STBC and SIC based receiver. IEEE Comm. Lett 2008, 12(2):115-117.El-Hajjar M, Alamri O, Wang J, Zummo S, Hanzo L: Layered steered space-time codes using multi-dimensional sphere packing modulation. IEEE Trans. Wireless Comm 2009, 8(7):3335-3340.Laneman JN, Wornell GW: Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks. IEEE Trans. Information Theory 2003, 49(10):2415-2425. 10.1109/TIT.2003.817829Barbarossa S, Pescosolido L, Ludovici D, Barbetta L, Scutari G: Cooperative wireless networks based on distributed space-time coding,. In International Workshop on Wireless Ad-Hoc Networks,. Oulu, Finland; 2004.Jing Y, Jafarkhani H: Using orthogonal and quasi-orthogonal designs in wireless relay networks. IEEE Trans. Information Theory 2007, 53(11):4106-4118.Hayes M, Kassim SK, Chambers JA, Macleod MD: Exploitation of quasi-orthogonal space time block codes in virtual antenna arrays: Part I - theoretical capacity and throughput gains,. In IEEE Vehicular Technology Conference, VTC Spring 2008,. Singapore; 2008:349-352. doi:10.1109/VETECS.2008.84Zou Y, Yao Y-D, Zheng B: Opportunistic distributed space-time coding for decode-and-forward cooperation systems. IEEE Trans. Signal Process, 60(4):2012.Kim J, Yang JR, Kim DI: Optimal relaying strategy for UE relays,. In Asia-Pacific Conference on Communications (APCC),. Sabah, Malaysia; 2011:192-196. doi:10.1109/APCC.2011.6152803Fan Y, Thompson J: MIMO configurations for relay channels: theory and practice. IEEE Trans. Wireless Commun 2007, 6(5):1774-1786.Schulz B: LTE Transmission Modes and Beamforming. Rohde and Schwarz White Paper 2011.Forutanpour B, Schevciw AGP, Visser E, Momeyer B: Variable beamforming with a mobile platform. US Patent 20120182429 2012

Biophysical Assessment of Single Cell Cytotoxicity: Diesel Exhaust Particle-Treated Human Aortic Endothelial Cells

Exposure to diesel exhaust particles (DEPs), a major source of traffic-related air pollution, has become a serious health concern due to its adverse influences on human health including cardiovascular and respiratory disorders. To elucidate the relationship between biophysical properties (cell topography, cytoskeleton organizations, and cell mechanics) and functions of endothelial cells exposed to DEPs, atomic force microscope (AFM) was applied to analyze the toxic effects of DEPs on a model cell line from human aortic endothelial cells (HAECs). Fluorescence microscopy and flow cytometry were also applied to further explore DEP-induced cytotoxicity in HAECs. Results revealed that DEPs could negatively impair cell viability and alter membrane nanostructures and cytoskeleton components in a dosage- and a time-dependent manner; and analyses suggested that DEPs-induced hyperpolarization in HAECs appeared in a time-dependent manner, implying DEP treatment would lead to vasodilation, which could be supported by down-regulation of cell biophysical properties (e.g., cell elasticity). These findings are consistent with the conclusion that DEP exposure triggers important biochemical and biophysical changes that would negatively impact the pathological development of cardiovascular diseases. For example, DEP intervention would be one cause of vasodilation, which will expand understanding of biophysical aspects associated with DEP cytotoxicity in HAECs