Miesmuschel-Langleinenkulturen – Vom wissenschaft-lichen Experiment zur wirtschaftlichen Umsetzung

The development of longline cultures for blue mussels (Mytilus edulis) at the German North Sea coast has been under way since 2001. It has turned out to be a successful and innovative method for the rearing of seeding mussels. The comparison of different tested longline types has proved that single longtubes carrying net collectors are the most stable system given the dynamic conditions in the Jade. Artificial collectors were settled by a large number of mussel larvae. Important settling took place between May and July, with 11 000 to 64 000 individuals per meter collector. The shell length of suspended mussels increased in their first summer at an average of 1.2 mm per week. Between the end of August until the end of September a mean of 2 to 9 kg mussels per meter equalling 4500 to 20 300 individuals per meter were harvested. Relayed on bottom cul-tures the mussel seed continued to grow and could be marketed as consumption mussels after their second summer

The Indonesian family planning program : an economic perspective

Indonesia has achieved one of the most impressive records in fertility reduction over the past two decades. The country's total fertility rate has declined froman estimated 5.5 in 1967 - 1970 to 3.4 in 1987. Population growth has been estimated at 2.1 percent during the eighties. Many observers credit Indonesia's National Family Planning Coordinating Board (BKKBN) as being instrumental in this fertility reduction and slowdown of population growth. BKKBN is a public sector organization responsible for planning and coordination of almost all family planning activities in Indonesia. The study objective is to provide BKKBN and the government of Indonesia with data that can help improve the cost-effectiveness of family planning delivery. The study examines resource allocation, cost, funding institutions, and output of the program at grassroots level in selected regencies in three provinces: West Java, the Special District of Yogyakarta, and South Kalimantan. It is based on data about the program's field operations collected during November 1986 - March 1987, and routine service statistics of BKKBN.Business in Development,Business Environment,Adolescent Health,Agricultural Research,Health Monitoring&Evaluation

A computational study of the interaction of organic surfactants with goethite α-FeO(OH) surfaces

We have studied the adsorption of three organic molecules onto different surfaces of goethite α−FeO(OH) using atomistic simulation techniques. New interatomic potentials for the interaction between goethite and the organic molecules were developed. In the majority of cases the organic molecules were found capable of forming a coordinate bond via their carbonyl oxygen atom with a surface iron ion. In addition, weaker hydrogen-bonds were formed between the organic molecules and the surfaces. The largest adsorption energies were obtained for the modes of adsorption where the organic molecules bridged or spanned the periodic grooves or dips present on the goethite surfaces, thus forming several interactions between the molecule and the surface. Among all adsorbates studied, the hydroxamic acid molecule in the eclipsed conformation releases the largest adsorption energy when it interacts with goethite surfaces, followed by the staggered conformations of hydroxyethanal and methanoic acid molecules. The adsorption energies are in the range of −60.0 to −186.4 kJ∙mol−1. Due to the surface structure, as well as the flexibility and size of hydroxamic acid and hydroxyethanal, in most cases these adsorbate molecules lose their planarity with respect to the structure of the isolated molecules. We found that the replacement of pre-adsorbed water by the organic adsorbates is an exothermic process on all the goethite surfaces studied. The removal by sorption onto iron particles of humic and fulvic acids, the major substituents of natural organic matter (NOM) that pollutes aquifers and soils, is corroborated by our calculations of the adsorption of surfactants with the same functional groups to the surfaces of oxidised iron particles

Africa-UK Partnership for the Computer-aided Development of Sustainable Catalysts

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Density Functional Theory Study of the Adsorption of Oxygen and Hydrogen on 3d Transition Metal Surfaces with Varying Magnetic Ordering

We have employed density functional theory (DFT) calculations to investigate the adsorption of molecular oxygen and hydrogen on 3d transition metal  (TM) surfaces with varying ordered magnetic structures in the bulk, namely ferromagnetic Fe(110), Co(0001), Ni(111) and diamagnetic Cu(111). The trend  observed in the energies of adsorption was compared with the magnetic moment of the cell using the d-band centre model of chemisorption and the    Stoner model of magnetic energy. As the gap between the d-band centre and the Fermi level of the TM decreases, more antibonding orbitals are present  above the Fermi level and thus unoccupied, leading to stronger binding. Correspondingly, the shift in the d-band centre decreases the density of states  (DOS) at the Fermi level giving rise to the ordered magnetic structure

High mobility n-channel organic field-effect transistors based on soluble C60 and C70 fullerene derivatives

We report on n-channel organic field-effect transistors (OFETs) based on the solution processable methanofullerenes [6,6]-phenyl-C61-butyric acid ester ([60]PCBM) and [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM). Despite the fact that both derivatives form glassy films when processed from solution, their electron mobilities are high and on the order of 0.21 cm2/V s and 0.1 cm2/V s, for [60]PCBM and [70]PCBM, respectively. Although the derived mobility of [60]PCBM is comparable to the best values reported in the literature, the electron mobility of [70]PCBM is the highest value reported to date for any C70 based molecule. We note that this is the only report in which C60 and C70 methanofullerenes exhibit comparable electron mobilities. The present findings could have significant implications in the area of large-area organic electronics and organic photovoltaics where C60 derivatives have so far been the most widely used electron acceptor materials.

Competitive Adsorption of H2O and SO2 on Catalytic Platinum Surfaces: a Density Functional Theory Study

Platinum has been widely used as the catalyst of choice for the production of hydrogen in the hybrid sulphur (HyS) cycle. In this cycle, water (H2O) and  sulphur dioxide (SO2) react to form sulphuric acid and hydrogen. However, the surface reactivity of platinum towards H2O and SO2 is not yet fully  understood, especially considering the competitive adsorption that may occur on the surface. In this study, we have carried out density functional theory  calculations with long-range dispersion corrections [DFT-D3-(BJ)] to investigate the competitive effect of both H2O and SO2 on the Pt (001), (011) and (111)  surfaces. Comparing the adsorption of a single H2O molecule on the various Pt surfaces, it was found that the lowest adsorption energy (Eads =  –1.758 eV) was obtained for the dissociative adsorption of H2O on the (001) surface, followed by the molecular adsorption on the (011) surface (Eads =  –0.699 eV) and (111) surface (Eads = –0.464 eV). For the molecular SO2 adsorption, the trend was similar, with the lowest adsorption energy (Eads = –2.471  eV) obtained on the (001) surface, followed by the (011) surface (Eads = –2.390 eV) and (111) surface (Eads = –1.852 eV). During competitive adsorption by  H2O and SO2, the SO2 molecule will therefore preferentially adsorb onto the Pt surface. If the concentration of SO2 increases, self-reaction between two  neighbouring SO2 molecules may occur, leading to the formation of sulphur monoxide (SO) and -trioxide (SO3) on the surface, which could lead to  sulphur poisoning of the Pt catalytic surfac

Catalytic formation of oxalic acid on the partially oxidised greigite Fe3S4(001) surface

Greigite (Fe3S4), with its ferredoxin-like 4Fe-4S redox centres, is a naturally occurring mineral capable of acting as a catalyst in the conversion of carbon dioxide (CO2) into low molecular-weight organic acids (LMWOAs), which are of paramount significance in several soil and plant processes as well as in the chemical industry. In this paper, we report the reaction between CO2 and water (H2O) to form oxalic acid (H2C2O4) on the partially oxidised greigite Fe3S4(001) surface by means of spin-polarised density functional theory calculations with on-site Coulomb corrections and long-range dispersion interactions (DFT+U−D2). We have calculated the bulk phase of Fe3S4 and the two reconstructed Tasker type 3 terminations of its (001) surface, whose properties are in good agreement with available experimental data. We have obtained the relevant phase diagram, showing that the Fe3S4(001) surface becomes 62.5% partially oxidised, by replacing S by O atoms, in the presence of water at the typical conditions of calcination [Mitchell et al. Faraday Discuss. 2021, 230, 30-51]. The adsorption and co-adsorption of the reactants on the partially oxidised Fe3S4(001) surface are exothermic processes. We have considered three mechanistic pathways to explain the formation of H2C2O4, showing that the coupling of the C-C bond and second protonation are the elementary steps with the largest energy penalty. Our calculations suggest that the partially oxidised Fe3S4(001) surface is a mineral phase that can catalyse the formation of H2C2O4 under favourable conditions, which has important implications for natural ecosystems and is a process that can be harnessed for the industrial manufacture of this organic acid

Controlling the Lithium Intercalation Voltage in the Li(Mn1–xNix)2O4 Spinel via Tuning of the Ni Concentration: a Density Functional Theory Study

LiMn2O4 spinel is a promising cathode material for secondary lithium-ion batteries. Despite showing a high average voltage of lithium intercalation, the material is structurally unstable, undergoing lowering of the crystal symmetry due to Jahn-Teller distortion of the six-fold Mn3+ cations. Although Ni has been proposed as a suitable substitutional dopant to improve the structural stability of LiMn2O4, and enhance the average lithium intercalation voltage,  the thermodynamics of the Ni incorporation and its effect on the electrochemical properties of this spinel material are not yet known. In this work, we  have employed density functional theory calculations with a Hubbard Hamiltonian (DFT+U) to investigate the thermodynamics of cation mixing in the  Li(Mn1–xNix)2O4 solid solution. Our results suggest LiMn1.5Ni0.5O4 is the most stable composition from room temperature up to at least 1000 K, in  agreement with experiments. We also found that the configurational entropy is much lower than the maximum entropy at 1000 K, indicating that higher  temperatures are required to reach a fully disordered solid solution. A maximum average lithium intercalation voltage of 4.8 eV was calculated for the  LiMn1.5Ni0.5O4 composition, which is very close to the experimental value. The temperature was found to have a negligible effect on the Li intercalation  voltage of the most stable composition. The findings reported here support the application of LiMn1.5Ni0.5O4 as a suitable cathode material for lithium-  ion batteries, with a highly stable voltage of intercalation under a wide range of temperatures.&nbsp