Abstract: In this chapter, the principles of statistical parameter estimation theory for a quantitative analysis of atomic-resolution electron microscopy images are introduced. Within this framework, electron microscopy images are described by a parametric statistical model. Here, parametric models are introduced for different types of electron microscopy images: reconstructed exit waves, annular dark-field (ADF) scanning transmission electron microscopy (STEM) images, and simultaneously acquired ADF and annular bright-field (ABF) STEM images. Furthermore, the Cramér-Rao lower bound (CRLB) is introduced, i.e. a theoretical lower bound on the variance of any unbiased estimator. This CRLB is used to quantify the precision of the structure parameters of interest, such as the atomic column positions and the integrated atomic column intensities.

Abstract: In this paper, a self-consistent fluid model is developed focusing on the plasma parameters in capacitively coupled 20% N 2-80% Ar discharges. Measurements of ion density are performed with the help of a floating double probe, and the emission intensities from Ar(4p) and N 2 ( B ) transitions are detected by an optical emission spectroscopy to estimate their relative densities. The consistency between the numerical and experimental results confirms the reliability of the simulation. Then the plasma characteristics, specifically the reaction mechanisms of active species, are analyzed under various voltages. The increasing voltage leads to a monotonous increase in species density, whereas a less homogeneous radial distribution is observed at a higher voltage. Due to the high concentration of Ar gas, Ar + becomes the main ion, followed by the N 2 +</mml:msubsup> ion. Besides the electron impact ionization of neutrals, the charge transfer processes of Ar +/ N 2 and N 2 +</mml:msubsup>/Ar are found to have an impact on the ionic species. The results indicate that adopting the lower charge transfer reaction rate coefficients weakens the Ar + ion density and yields a higher N 2 +</mml:msubsup> ion density. However, the effect on the species spatial distributions and other species densities is limited. As for the excited-state species, the electron impact excitation of background gases remains overwhelming in the formation of Ar(4p), N 2 ( B ), and N 2 ( a ' ), whereas the <mml:msub> N 2 ( A ) molecules are mainly formed by the decay of <mml:msub> N 2 ( B ). In addition, the dissociation of <mml:msub> N 2 collided by excited-state Ar atoms dominates the N generation, which are mostly depleted to produce N + ions.

Abstract: In this paper, two new monolayers, namely PtOS and PtOSe, are theoretically predicted using first-principles calculations. Structural, electronic, optical and thermoelectric properties are explored using full-potential linearized augmented plane-wave (FP-LAPW) method and the semiclassical Boltzmann transport theory. Predicted two-dimensional (2D) materials show good dynamical, thermodynamic and structural stability. Calculated electronic structures indicate the indirect gap semiconductor nature of the PtOS and PtOSe single layers with energy gap of 1.346(2.436) and 0.978(1.978) eV as calculated with the WC(HSE06) functional, respectively. Density of states spectra and valence charge distribution maps suggest a mix of covalent and ionic characters of the chemical bonds. 2D materials at hand exhibit good absorption property in the visible regime with coefficient value reaching the order of 105/cm, even much larger in the ultraviolet, suggesting the promising optoelectronic applicability. Finally, the thermoelectric parameters including electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and figure of merit are determined and analyzed. Results indicate prospective thermoelectric performance of both considered single layers as demonstrated by large figure of merit close to unity. Our work introduces two new 2D multifunctional materials that may possess potential applications in the optoelectronic and thermoelectric nano-devices.

Abstract: In this study, the structural, electronic and optical properties of theoretically predicted C6N monolayer structure are investigated by means of Density Functional Theory-based First-Principles Calculations. Phonon band dispersion calculations and molecular dynamics simulations reveal the dynamical and thermal stability of the C6N single-layer structure. We found out that the C6N monolayer has large negative in-plane Poisson's ratios along both X and Y direction and the both values are almost four times that of the famous-pentagraphene. The electronic structure shows that C6N monolayer is a semi-metal and has a Dirac-point in the BZ. The optical analysis using the random phase approximation method constructed over HSE06 illustrates that the first peak of absorption coefficient of the C6N monolayer along all polarizations is located in the IR range of spectrum, while the second absorption peak occurs in the visible range, which suggests its potential applications in optical and electronic devices. Interestingly, optically anisotropic character of this system is highly desirable for the design of polarization-sensitive photodetectors. Thermoelectric properties such as Seebeck coefficient, electrical conductivity, electronic thermal conductivity and power factor are investigated as a function of carrier doping at temperatures 300, 400, and 500 K. In general, we predict that the C6N monolayer could be a new platform for study of novel physical properties in two-dimensional semi-metal materials, which may provide new opportunities to realize high-speed low-dissipation devices.

Abstract: In this thesis, a first-principles research to tune the physical properties of group III-V materials in the thinnest limit is carried out. Among the different methods to tune the mechanical, electronic and magnetic properties of these graphene related materials, we use: two-dimensional (2D) multilayers, straintronics, hydrogen functionalization, and transition metal adsorption. The first part of this research is devoted to a complete characterization of the structural, electronic, mechanical and vibrational properties of 2D group III-As monolayers, obtained from density functional theory. Our findings are used to understand the contribution of the

Abstract: In this work, the carbon (C) and silicon (Si) doping and codoping effects on beta-arsenene (As) monolayer structural, electronic, and magnetic properties have been comprehensively investigated using first-principles calculations. The studied two-dimensional (2D) materials exhibit good stability. Pristine beta-As single layer is an indirect gap semiconductor with a band gap of 1.867(2.441) eV as determined by PBE(HSE06) functional. Due to the difference in atomic size and electronic interactions, C and Si substitution induces a significant local structural distortion. Depending upon dopant concentration and doping sites, feature-rich electronic properties including non-magnetic semiconductor, magnetic semiconductor and half-metallicity may be obtained, which result from p-p interactions. High spin-polarization at the Fermi level vicinity and significant magnetism suggest As:1C, As:2C, As:1Si, As:2Si, and As:CSi systems as prospective spintronic 2D materials. While, the C-C, Si-Si, and C-Si dimer doping decreases electronic band gap, making the layer more suitable for applications in optoelectronic devices. Results presented herein may suggest an efficient approach to create novel multi-functional 2D materials from beta-As monolayer.

Abstract: In this work, we report an anomalous phenomenon on superelastic cycling of NiTi shape memory alloys when deforming at the temperature close to the border of superelastic window. New unexpected effects are found-(i) critical stress for inducing martensite transformation during the second loading cycle is higher than that of the first cycle; ( ii ) the plateau stress of the second cycle decreases to the original level when the strain overcomes the limit of the first cycle; ( iii ) transition from good superelasticity in the first cycle to fully irreversible strain in the second. We propose that defects generated during the first superelastic cycle close to the border of superelastic window impede following stress-induced martensitic transformations, leading to the increase of critical stress beyond yield stress of the B2 matrix, and thus functional fatigue of NiTi alloys. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Abstract: Increasing efforts are directed towards the development of sustainable alternative protein sources among which microbial protein (MP) is one of the most promising. Especially when waste streams are used as substrates, the case for MP could become environmentally favorable. The risks of using organic waste streams for MP production–the presence of pathogens or toxicants–can be mitigated by their anaerobic digestion and subsequent aerobic assimilation of the (filter-sterilized) biogas. Even though methane and hydrogen oxidizing bacteria (MOB and HOB) have been intensively studied for MP production, the potential benefits of their co-cultivation remain elusive. Here, we isolated a diverse group of novel HOB (that were capable of autotrophic metabolism), and co-cultured them with a defined set of MOB, which could be grown on a mixture of biogas and H2/O2. The combination of MOB and HOB, apart from the CH4 and CO2 contained in biogas, can also enable the valorization of the CO2 that results from the oxidation of methane by the MOB. Different MOB and HOB combinations were grown in serum vials to identify the best-performing ones. We observed synergistic effects on growth for several combinations, and in all combinations a co-culture consisting out of both HOB and MOB could be maintained during five days of cultivation. Relative to the axenic growth, five out of the ten co-cultures exhibited 1.1–3.8 times higher protein concentration and two combinations presented 2.4–6.1 times higher essential amino acid content. The MP produced in this study generally contained lower amounts of the essential amino acids histidine, lysine and threonine, compared to tofu and fishmeal. The most promising combination in terms of protein concentration and essential amino acid profile was Methyloparacoccus murrelli LMG 27482 with Cupriavidus necator LMG 1201. Microbial protein from M. murrelli and C. necator requires 27–67% less quantity than chicken, whole egg and tofu, while it only requires 15% more quantity than the amino acid-dense soybean to cover the needs of an average adult. In conclusion, while limitations still exist, the co-cultivation of MOB and HOB creates an alternative route for MP production leveraging safe and sustainably-produced gaseous substrates.

Abstract: Industrial production of HCN from NH3 and CH4 not only uses precious Pt or Pt−Rh catalysts but also requires extremely high temperatures (∼1600 K). From an energetic, operational, and safety perspective, a drastic decrease in temperature is highly desirable. Here, we report ammonia reforming of methane for the production of HCN and H2 at 673 K by the combination of CH4/NH3 plasma and a supported Cu/silicalite-1 catalyst. 30% CH4 conversion has been achieved with 79% HCN selectivity. Catalyst characterization and plasma diagnostics reveal that the excellent reaction performance is attributed to metallic Cu active sites. In addition, we propose a possible reaction pathway, viz. E-R reactions with N, NH, NH2, and CH radicals produced in the plasma, for the production of HCN, based on density functional theory calculations. Importantly, the Cu/silicalite-1 catalyst costs less than 5% of the commercial Pt mesh catalyst.

Abstract: Intending to tackle road traffic noise in urban environments, noise barriers have been proven to effectively reduce environmental noise levels, leading to positive effects on noise perception by the exposed population. This work assesses the impacts of replacing an obsolete noise barrier in a site near a highway. The effects of this change were monitored via a combination of field surveys, acoustic measurements and noise maps. The results have shown that even though the barrier replacement led to a 4.1 dB reduction in the LA,eq,(15 min.), the annoyance levels of the respondents increased. Possibly, the expectations regarding the improvement of the noise barrier were not met, after a history of complaints. Additionally, existing exposure-response relationships were not successful in predicting the annoyance levels in this particular case. In this dataset, noise annoyance presented a weak link with reported health problems, while a strong correlation was found with the comfort level to perform activities outdoors. Questions regarding the COVID-19 pandemic showed that even though the respondents were spending more time at home, they were less annoyed due to road traffic noise in the period when circulation restrictions were in place.

Abstract: Lakes provide considerable social, economic, and ecological benefits. However, lakes are shrinking and the water quality is declining, due to human pressures such as water withdrawal and land use change, particularly in the developing world. Despite this, information regarding the economic impact of lake level reduction and local willingness to support restoration programs is lacking. This study employed a contingent valuation method to estimate willingness to pay and to contribute labor to Lake Ziway restoration program, Ethiopia. Face-to-face interviews were administered to 259 randomly selected respondents. Our findings revealed that about one-third of the respondents are willing to pay and about two-third are willing to contribute labor to restore the lake. From the interval regression models, the annual mean willingness to pay was estimated about 21.0 USD for the status quo scenario (the program works to keep water levels constant at current levels) and 31.1 USD for the improvement scenario (the program works to increase the water levels permanently). The annual mean willingness to contribute labor was estimated about 27.7 man-days for the status quo and 39.3 man-days for the improvement scenarios. 'Farm income' positively influenced the willingness to pay together with 'farm plot area.' Similarly, labor contribution was positively influenced by 'farm plot area' and 'education' and negatively by 'farm plot distance.' The economic values derived from this study reflect societal preferences and can form a significant input for policymakers, in support of informed and evidence-based decision-making regarding lake management and restoration in developing countries like Ethiopia.

Abstract: Landfill mining refers to the re-circulation of resources from the previously deposited wastes–integrating resource recovery with traditional site remediation. Several resources that can be recovered include scrap metals, combustibles, and inert materials. In addition, land can be recovered or landfill void space can be liberated for future wastes. At present, landfill mining is still an emerging concept with few project implementations. Consequently, the assessments of its economic and climate implications are case study-specific, limiting the understanding of its potential in a wider geographical scope. This thesis aims to assess the economic performance and climate impact of landfill mining in Europe towards the development of sound strategies for implementation. Different project setups are assessed in relation to varying factors at the site level such as waste composition and landfill settings, and at the system level such as policy and market conditions and background material and energy. In doing so, a factor-based method is developed and applied to generate multiple scenarios (531, 441 scenarios per project setup) and determine the underlying important factors and their interrelations that drive the results. Such understanding is used to develop and discuss strategies for improvement by addressing relevant questions for specific stakeholders, including project investors (i.e., which landfill sites to prioritize?), landfill mining practitioners (i.e., how to set up such projects?), and policymakers (i.e., which policy instruments can effectively support such projects?). Results show that landfill mining is preferable in terms of climate than economy. Possible improvements are shown by internalizing thermal treatment of combustibles and extending fines residue utilization as construction aggregates. In relation to the choice of project setups, preferable site and system-level conditions are identified in general but it is also discussed that the plausibility of finding such conditions may be difficult at present. This steers the development of more tailored strategies on what can be done now by the landfill practitioners in terms of setting up projects under current policy and market conditions in specific regions, or what can be done by the policymakers in terms of implementing various policy instruments that can drive such changes at the system level. Through this thesis, the future of landfill mining research is guided towards addressing key challenges and potential solutions for improvement. Furthermore, this thesis highlights the role of assessment as a tool for learning and guiding the development of emerging concepts such as landfill mining.

Abstract: Latest synthesis of ZnSb monolayer, encouraged us to conduct density functional theory (DFT) simulations in order to study the structural, magnetic, electronic/optical and mechanical features of the sp2-hybridized honeycomb ZnSb monolayer (ML-ZnSb) and bilayer (BL-ZnSb). Our structural optimizations reveal that ML-ZnSb is an anisotropic hexagonal structure while BL-ZnSb is composed of shifted ZnSb layers which are covalently binded. ML-ZnSb is found to be a ferromagnetic metal, in contrast BL-ZnSb has a non-magnetic indirect band gap semiconducting ground state. For the in-plane polarization, first absorption peak of ML-ZnSb and BL-ZnSb confirm the absorbance of the light within the infrared domain wand visible range, respectively. Moreover, our results reveal that the layer-layer chemical bonding in BL-ZnSb significantly enhances the mechanical response of ML-ZnSb whose in-plane stiness is the smallest among all 2D materials (2DM). Notably, the strong in-plane anisotropy of ML-ZnSb in its stiness reduces in BL-ZnSb.

Abstract: Leaf shape is closely related to economics of leaf support and leaf functions, including light interception, water use, and CO2 uptake, so correct quantification of leaf shape is helpful for studies of leaf structure/function relationships. There are some extant indices for quantifying leaf shape, including the leaf width/length ratio (W/L), leaf shape fractal dimension (FD), leaf dissection index, leaf roundness index, standardized bilateral symmetrical index, etc. W/L ratio is the simplest to calculate, and recent studies have shown the importance of the W/L ratio in explaining the scaling exponent of leaf dry mass vs. leaf surface area and that of leaf surface area vs. leaf length. Nevertheless, whether the W/L ratio could reflect sufficient geometrical information of leaf shape has been not tested. The FD might be the most accurate measure for the complexity of leaf shape because it can characterize the extent of the self-similarity and other planar geometrical features of leaf shape. However, it is unknown how strongly different indices of leaf shape complexity correlate with each other, especially whether W/L ratio and FD are highly correlated. In this study, the leaves of nine Magnoliaceae species (>140 leaves for each species) were chosen for the study. We calculated the FD value for each leaf using the box-counting approach, and measured leaf fresh mass, surface area, perimeter, length, and width. We found that FD is significantly correlated to the W/L ratio and leaf length. However, the correlation between FD and the W/L ratio was far stronger than that between FD and leaf length for each of the nine species. There were no strong correlations between FD and other leaf characteristics, including leaf area, ratio of leaf perimeter to area, fresh mass, ratio of leaf fresh mass to area, and leaf roundness index. Given the strong correlation between FD and W/L, we suggest that the simpler index, W/L ratio, can provide sufficient information of leaf shape for similarly-shaped leaves. Future studies are needed to characterize the relationships among FD and W/L in leaves with strongly varying shape, e.g., in highly dissected leaves.

Abstract: Like nanomaterials, bacteria have been unknowingly used for centuries. They hold significant economic potential for fuel and medicinal compound production. Their full exploitation, however, is impeded by low biological activity and stability in industrial reactors. Though cellular encapsulation addresses these limitations, cell survival is usually compromised due to shell-to-cell contacts and low permeability. Here, we report ordered packing of silica nanocolloids with organized, uniform and tunable nanoporosities for single cyanobacterium nanoencapsulation using protamine as an electrostatic template. A space between the capsule shell and the cell is created by controlled internalization of protamine, resulting in a highly ordered porous shell-void-cell structure formation. These unique yolk-shell nano structures provide long-term cell viability with superior photosynthetic activities and resistance in harsh environments. In addition, engineering the colloidal packing allows tunable shell-pore diameter for size-dependent permeability and introduction of new functionalities for specific molecular recognition. Our strategy could significantly enhance the activity and stability of cyanobacteria for various nanobiotechnological applications.