Abstract: Maritime transport of benzene is regulated by the International Maritime Organisation (IMO). Two important guidelines for a ships crew in this matter are IMO circulars 1095 and 1220. The first one describes the minimum safety standards for ships carrying liquids in bulk containing benzene while circular 1220 deals with structural guidelines for new ships carrying liquids in bulk containing benzene, but also technical developments could help in improving safety and health protection on board chemical tankers carrying benzene in bulk. The aim of the present paper is to determine the benzene concentration in the working and living environment on board a modern chemical tanker carrying benzene in bulk, where all safety, technical and operational procedures described by IMO in the above-mentioned circulars are followed. During specific cargo operations, we measured the benzene concentrations on different locations on board by means of Radiello® passive diffusive samplers. Despite all measures taken, we found an important difference in benzene concentration between operations with a benzene cargo compared to operations without benzene on board, as well as inside and outside the accommodation. Moreover, even during discharge operations, where the emission is theoretically zero, we found an important increase in the benzene concentration. In addition, we found less favourable results for the engine room.

Abstract: In the broad context of food and environmental safety, the development of selective and sensitive analytical tools for the detection of β-lactam antibiotics in milk down to their Maximum Residues Limits (MRL), is still an open challenge. To address this need, the design of new bio(mimetic) electrochemical sensors was investigated in the present thesis. These sensors are based on the intrinsic electrochemistry of β-lactam antibiotics, taking advantages of the characteristic electrochemical fingerprints of the core structures and redox active side chain groups. The electrochemistry of nafcillin (NAF) and the isoxazolyl penicillins (ISOXA) was investigated, identifying the peculiar electrochemical fingerprint of each antibiotic, proving that it is possible to use electrochemistry for the selective detection of these antimicrobial drugs. Once verified the applicability of a direct detection, different sensor configurations were tested mainly focusing on: – the selection and validation of aptamers to be used as bioreceptors in the development of β-lactam biosensors; – the design of biomimetic receptors, particularly molecularly imprinted polymers, and other synthetic electrode modifiers compatible with a direct detection strategy. The selection of novel aptamers was performed following both a traditional FluMag SELEX protocol and a novel variant based on graphene oxide (GO). First results with the modified GO-SELEX are promising but more work still needs to be done to validate this novel approach. The few aptamers for β-lactam antibiotics, already reported in literature by other groups, were poorly characterized up to now. For this reason, a multi-analytical characterization protocol for aptamer binding studies was optimized and validated by focusing on aptamer AMP17 against ampicillin. The protocol combines ITC, nESI-MS and 1H-NMR. Very striking was the fact that the aptamer sequence did not show any sign of specific binding for its target, even if it was used in many other studies in the past. This thesis now offers a validated protocol for testing the affinity and binding capabilities of aptamer sequences. In parallel, the functionalization of the electrode surface with polymer modifiers was studied. In particular we optimized a MIP electrochemical sensor based on 4-aminobenzoic acid for the direct electrochemical detection of CFQ. Another approach was tested based on the intrinsic affinity of NAF for an oPD electropolymerized film on the electrode surface. Both sensors were found to be sensitive and selective for the detection of CFQ and NAF at MRLs in buffer solutions. The proposed protocols are robust and promising for technological transfer. Lastly, the research activity was directed towards milk sample analysis following two parallel routes: the development of a pre-treatment protocol for raw milk, based on solvent addition (ACN or ISO), and the study of β-lactam antibiotics electrochemistry in undiluted raw milk with addition of KNO3 as supporting electrolyte. Both approaches gave encouraging results and the detection of NAF, CFQ and CFU in the micromolar range was achieved, with the second approach in undiluted raw milk.

Abstract: The molecular genetics of flower development have been studied extensively for more than two decades. Fusion of organs and the tendency to oligomery, important characteristics of flower evolution, so far have remained fairly elusive. We present a geometric model for shape and fusion in the corolla of Asclepiads. Examples demonstrate how fusion of petals creates stable centers, a prerequisite for the formation of complex pollination structures via congenital and postgenital fusion events, with the formation of de novo organs, specific to Asclepiads. The development of the corolla reduces to simple inequalities from the MATHS-BOX. The formation of stable centers and of bell and tubular shapes in flowers are immediate and logical consequences of the shape. Our model shows that any study on flowers, especially in evo-devo perspective should be performed within the wider framework of polymery and oligomery and of fusion and synorganization.

Abstract: In the biogeochemical flows on Earth, the reactive nitrogen (Nr) level has three times surpassed the safe boundary. The severe transgression of this boundary goes against sustainable planetary development. The modern food production process excessively relies on synthetic Nr fertilizers from the Haber– Bosch process. However, the massive loss of valuable nitrogen resources (i.e., 78-89%) from agriculture has been causing severe nitrogen cascade. Besides, the domestic wastewater in some local areas is discharged without proper treatment, making it a nonnegligible source of Nr pollution for local water bodies. Anthropogenic activities keep pumping out Nr pollution via point-source and non-point-source (NPS) emissions. Compared to the NPS emissions, point sources give visible and identified waste streams. It is vital to intervene the nitrogen cascade from point sources and facilitate humanity back to the safe Nr boundary. The collected and collectible Nr streams from food production, waste management, and recycling secondary raw materials can be used as waste-based fertilizers for agricultural cultivation. Besides the well-investigated recovery of inorganic Nr, organic Nr accounts for a massive Nr proportion on the Earth. Proper handling and treatment make these useful organic fertilizers for soil-based cultivation. However, these organic Nr fertilizers cannot directly apply to fertigation or hydroponic cultivation systems, and further biological conversion via nitrogen mineralization and nitrification to nitrate is essential. Besides the direct Nr cycling, the indirect Nr cycling ‘over the atmosphere’ should also be considered. In this way, the nitrogen cycle can be completed via converting the waste Nr back to nitrogen gas (i.e., Nr removal) and then synthesizing into Nr again. The municipal wastewater treatment plants receive a vast amount of low-strength Nr wastewater (mainly as ammonium) daily. Compared to the conventional nitrification/denitrification process, partial nitritation/anammox (PN/A) is considered a resource- and cost-effective technology for wastewater with a low COD/N ratio. Moreover, the novel autotrophic denitratation/anammox process could be a good Nr removal process for wastewater containing both ammonium and nitrate. This Ph.D. thesis aimed to develop Nr recovery, conversion, and removal bioreactor strategies for different types of waste streams and biomass. Nr recovery was investigated on high-strength Nr waste streams for fertigation or hydroponic applications in Chapters 2 and 3. On the other hand, Nr removal was studied on the medium- to low-strength Nr waste streams in Chapters 4 and 5. In Chapter 2, a novel mineralization and nitrification system was proposed, producing nutrient solutions from solid organic fertilizers for hydroponic systems. Batch tests showed that aerobic incubation at 35°C could realize the NO₃⁻-N production efficiency above 90% from a novel microbial fertilizer. Subsequently, in the stirred tank bioreactor test, NO₃⁻-N production efficiency stabilized in a range of 44-51% under the influent loading rate of 400 mg TN L⁻¹ d⁻¹ at a 5-day HRT. Using Ca(OH)₂ and Mg(OH)₂ as pH control reagents generated the nutrient solutions with different P, Ca, and Mg nutrient levels. After modeling the nutrient balancing process, the proportion of organic-sourced NO₃⁻-N in the Hoagland nutrient solution (HNS) of Ca(OH)₂ scenario was 92.7%, while only 37.4% in the Mg(OH)₂ scenario. Compared to commercial scenarios, the total costs of the organic-sourced HNS can be cost-competitive for hydroponic cultivation. In Chapter 3, the Nr recovery as nitrate (NO₃⁻-N) from diluted human urine (around 670 mg N L⁻¹) was explored in a trickling filter (TF) for the first time. A novel concept of in-situ integrating the TF system into hydroponic systems was proposed as meaningful progress towards sustainable agriculture. The difference between synthetic and real urine in nitrification efficiency was found to be negligible. The full nitrification of alkalinized real urine was realized in the pH-controlled TF by calcium hydroxide (Ca(OH)₂) at around pH 6. The TF could handle different urine collection batches and maintain relatively stable nitrification performance, with NO₃⁻-N production efficiency and rate of 88±3% and 136±4 mg N L⁻¹ d⁻¹, respectively. The optimal HLR to realize this nitrification performance was 2 m³ m⁻² h⁻¹, with energy consumption of 1.8 kWh electricity kg⁻¹ NO₃⁻-N production. Ca(OH)₂, as a cheap base, its triple advantages on urine alkalinization, full nitrification, and macronutrient supplementation were successfully demonstrated in our proposed concept. In Chapter 4, towards more sustainable wastewater treatment, the feasibility of one-stage partial nitritation/anammox (PN/A) was investigated in three parallel packed-bed trickling filters (TFs), with three types of carrier materials of different specific surface areas. Synthetic wastewater containing 100-250 mg NH₄⁺-N L⁻¹ was tested to mimic medium-strength household waste streams after carbon removal. Interestingly, the cheap carrier based on expanded clay achieved similar rates as commercially used plastic carrier materials. The top passive ventilation combined with an optimum hydraulic loading rate of 1.8 m³ m⁻² h⁻¹ could reach approximately 60% total nitrogen (TN) removal at a rate of 300 mg N L⁻¹ d⁻¹. A relatively low NO₃⁻-N production (13%) via PN/A was achieved in TFs. Most of the TN removal took place in the top compartment, where anammox activity was the highest. Energy consumption estimation (0.78 kWh electricity g⁻¹ N removed) suggested that the proposed process could be a suitable low-cost alternative for nitrogen removal. In Chapter 5, coupling sulfur-driven denitratation (SDN) with anammox was proposed to treat the wastewater containing both NO₃⁻-N and NH₄⁺-N, like the secondary effluents of mainstream PN/A processes. To explore the feasibility of sufficient and stable NO₂⁻-N accumulation via SDN in the long term, the effects of pH setpoints, residual NO₃⁻-N level, and biomass-specific NO₃⁻-N loading rate (BSNLR) were investigated. Alternating the pH setpoints between 7.0 and 8.5 could temporarily stimulate the NO₂⁻-N accumulation. Both the residual NO₃⁻-N and BSNLR showed highly positive correlations with the NO₂⁻-N accumulation efficiency. Under the control of pH 8.5, 1.0±0.8 mg NO₃⁻-N L⁻¹ and 150±42 mg NO₃⁻-N g⁻¹ VSS d⁻¹, SDN could produce 6.4±1.0 mg NO₂⁻-N L⁻¹ in the short term. Thiobacillus members may play a crucial role in managing the NO₂⁻-N accumulation, but the reduction of abundance and possible adaptation significantly impaired the efficacy of control strategies in the long run. Overall, novel technologies have been proposed to sustainably convert Nr in waste streams and biomass. The decision for Nr recovery versus removal and synthesis should be based on specific cases with the best environmental, economic, and human-health sustainability. In the future, the Nr management concepts should be further improved to make the nitrogen cycle more sustainable with higher resource use efficiency and less Nr emissions to the environment. Although the thesis is mainly focused on limited types of Nr waste streams, it pointed out the direction of sustainable Nr management and could facilitate the Nr back to the safe boundary in the long run.

Abstract: Van der Waals quantum wells, naturally formed in two-dimensional layered materials with nanoscale thickness, possess many inherent advantages over conventional molecular beam epitaxy grown counterparts, and could bring up intriguing physics and applications. However, optical transitions originated from the series of quantized states in these emerging quantum wells are still elusive. Here, we show that multilayer black phosphorus appears to be an excellent candidate for van der Waals quantum wells with well-defined subbands and high optical quality. Using infrared absorption spectroscopy, we probe subband structures of multilayer black phosphorus with tens of atomic layers, revealing clear signatures for optical transitions with subband index as high as 10, far from what was attainable previously. Surprisingly, in addition to allowed transitions, an unexpected series of “forbidden” transitions is also evidently observed, which enables us to determine energy spacings separately for conduction and valence subbands. Furthermore, the linear tunability of subband spacings by temperature and strain is demonstrated. Our results are expected to facilitate potential applications for infrared optoelectronics based on tunable van der Waals quantum wells.

Abstract: A polynomial approach is applied for a number of data from the Posener-tables to calculate the values of the intensity distribution function of atomic absorption lines – H(a, 0.726a) – at the tabulated damping-parameter values with an error not worse than 0.044 %. For the resultant H(a, 0.726a) data, the ninth and sixth order polynomials can be fitted according to the damping parameter range of 0-2, and 2-10, respectively, which results in a minimal error of approximation. The derived functions are simply applicable to the calculation of any H(a, 0.726a) value belonging to a damping-parameter of any arbitrarily selected spectral line, implying the influence of Doppler- and Lorentz-broadening. The overall error of the described method is lower than 0.4 %.

Abstract: The development cost-effective life support technologies is a highly relevant topic for space biology. Currently, food and water supply during space flights is currently restricted by technical and economic constraints: daily water consumption of an average crew of 6 members is about 72 L, with an estimated cost of 2,160,000 d-1. To reduce these costs and sustain long term space missions, the European Space Agency designed MELiSSA, an artificial ecosystem based on 5 compartments for the recycling gas, liquid and solid waste (Lasseur et al., 2011). In the CI stage, crew and inedible solid waste is fermented by thermophilic anaerobic bacteria, producing volatile fatty acids (VFAs), CO2 and ammonium (NH4+). In the CII compartment the VFAs are converted into edible biomass, using the photoheterotroph Rodospirillum rubrum. Afterwards, the nitrifying CIII unit converts toxic levels of ammonia/ammonium into nitrate, which enables the effluent to be fed to the photoautotrohopic CIV stage, that provides food and oxygen for the crew (Godia et al., 2002). The highest nitrogen flux in a Life Support System is human urine. As nitrate is the preferred form of nitrogen fertilizer for hydroponic plant cultivation, urine nitrification is an essential process in the MELiSSA loop. The development of the Additional Unit for Water Treatment or Urine NItrification ConsortiUM (UNICUM) requires the selection and characterization of the microorganisms that will be used. The key microorganisms in the biological treatment of urine are heterotrophs, for the hydrolysis of urea into ammonia and carbon dioxide, Ammonia Oxidizing Bacteria (AOB), for the ammonia oxidation into nitrite and Nitrite Oxidizing Bacteria (NOB), for the conversion of nitrite into nitrate. The strains were selected according to predefined safety (non sporogenic and BSL 1) and metabolic (Ks, μmax) criteria. To evaluate functional consortia for space applications, ureolysis, nitritation and nitratation of the selected microorganisms and synthetic communities were elucidated. Additionally, urine is a matrix with a high salt content. Unhydrolised urine's EC ranges from 1.1 to 33.9 mS/cm, the mean value being 21.5 mS/cm (Marickar, 2010), while hydrolysed urine can reach higher levels, up to 75 mS/cm. This conditions could inhibit microbial metabolism, therefore the effect of salinity on urine nitrification was also elucidated.

Abstract: We have developed an innovative methodology to overcome the lack of techniques for real-time assessment of degradable biomedical polymers at physiological conditions. The methodology was established by combining polymer characterization techniques with electrochemical sensors. The in vitro hydrolytic degradation of a series of aliphatic polyesters was evaluated by following the molar mass decrease and the mass loss at different incubation times while tracing pH and l-lactate released into the incubation media with customized miniaturized electrochemical sensors. The combination of different analytical approaches provided new insights into the mechanistic and kinetics aspects of the degradation of these biomedical materials. Although molar mass had to reach threshold values for soluble oligomers to be formed and specimens’ resorption to occur, the pH variation and l-lactate concentration were direct evidence of the resorption of the polymers and indicative of the extent of chain scission. Linear models were found for pH and released l-lactate as a function of mass loss for the l-lactide-based copolymers. The methodology should enable the sequential screening of degradable polymers at physiological conditions and has potential to be used for preclinical material’s evaluation aiming at reducing animal tests.

Abstract: We model transport through two-dimensional topological insulator (TI) nanoribbons. To model the quantum transport, we employ the non-equilibrium Green's function approach. With the presented approach, we study the effect of lattice imperfections on the carrier transport. We observe that the topologically protected edge states of TIs are robust against a high percentage (2%) of vacancy defects. We also investigate tunneling of the edge states in two decoupled TI nanoribbons.