Regional Pathways to Complexity

Synthesizing almost 30 years of Dutch archaeological research in central and southern Italy, this book discusses and compares settlement and land use patterns from the late protohistoric period to the late Roman Republic. Exploring both social and environmental explanations, as well as interregional parallellisms and divergences, the authors take a multi-scalar approach (from micro-regional to supra-regional) to the long-term development of indigenous Bronze Age tribal pastoralist societies towards the complexity of urbanized Roman society. The culmination of a joint project conducted between 1997 and 2005, the comparative perspective offered by this book is based on the results of long-term landscape archaeological fieldwork projects by the Groningen Institute of Archaeology (in Lazio and Calabria) and the Archaeological Centre of the Free University (in Puglia)

Structural phase transitions and magnetic superexchange in MIAgIIF3 perovskites at high pressure

Pressure induced phase transitions of MIAgIIF3 perovskites where M = K, Rb, Cs, have been predicted theoretically for the first time for pressures up to 100 GPa. The sequence of phase transitions for M = K and Rb consists of an orthorhombic to monoclinic and back to orthorhombic transition, associated with progressive bending of infinite chains of corner sharing [AgF6]4 minus octahedra and their mutual approaching via secondary Ag...F contacts. In stark contrast, only a single phase transition i.e. tetragonal to triclinic, is predicted for CsAgF3, associated with substantial deformation of the Jahn Teller-distorted first coordination sphere of AgII and association of the infinite [AgF6]4 minus chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF3 hosts lattices.Comment: 7 pages, 3 figures, and electronic supplement of 25 page

Ag(II) as spin super-polarizer in metal fluoride clusters

Using quantum mechanical calculations, we examine magnetic (super)exchange interactions in prototypal molecular fluoride clusters containing late transition metals or selected lanthanides, as well as Ag(II). By referencing to analogous species comprising closed shell Cd(II) we provide evidence that the presence of Ag(II) may modify the magnetic properties of such systems (including metal metal superexchange) to an unprecedented degree, specifically both coupling sign and strength may markedly change. Remarkably, this happens in spite of the fact that the fluoride ligand is the least susceptible to spin polarization among all monoatomic ligands known in chemistry. Ag(II), with one hole in its d shell, stands as spin superpolarizer, and this feature could be exploited in spintronics and diverse molecular devices.Comment: 6 pages, 3 figures, 2 tables, and 19 pages of supplementary informatio

Phthalocyanine-polyoxotungstate lanthanide double deckers

Acetate ligand metathesis results in the first hybrid [MIII(Pc)(PW11O39)]6− (M = Y, Dy, Tb) double-decker scaffolds, where a phthalocyanate (Pc2−) and one of the conceptually most simple polyoxotungstates, a monolacunary Keggin cluster, are interlinked via a single rare earth ion. Characterisation includes high-resolution mass spectrometry, synchrotron-based single-crystal X-ray diffraction, various spectroscopic and electrochemical methods, and magnetic studies revealing slow relaxation of the magnetisation for the Dy derivate

Conductive Self-Assembled Monolayers of Paramagnetic {CoIICo4III} and {Co4IICo2III} Coordination Clusters on Gold Surfaces

Two polynuclear cobalt(II,III) complexes, [Co5(N3)4(N-n-bda)4(bza·SMe)2] (1) and [Co6(N3)4(N-n-bda)2(bza·SMe)5(MeOH)4]Cl (2), where Hbza·SMe = 4-(methylthio)benzoic acid and N-n-H2bda = N-n-butyldiethanolamine, were synthesized and fully characterized by various techniques. Compound 1 exhibits an unusual, approximately C2-symmetric {CoII Co4II } core of two isosceles Co3 triangles with perpendicularly oriented planes, sharing a central, high-spin CoII ion residing in a distorted tetrahedral coordination environment. This central CoII ion is connected to four outer, octahedrally coordinated low-spin CoIII ions via oxo bridges. Compound 2 comprises a semi-circular {Co4IICo2III } motif of four non-interacting high-spin CoII and two low-spin CoIII centers in octahedral coordination environments. Self-assembled monolayers (SAMs) of 1 and 2 were physisorbed on template-stripped gold surfaces contacted by an eutectic gallium-indium (EGaIn) tip. The acquired current density-voltage (I-V) data revealed that the cobalt-based SAMs are more electrically robust than those of the previously reported dinuclear {CuIILnIII} complexes with Ln = Gd, Tb, Dy, or Y (Schmitz et al., 2018a). In addition, between 170 and 220°C, the neutral, mixed-valence compound 1 undergoes a redox modification, yielding a {Co5}-based coordination cluster (1-A) with five non-interacting, high-spin octahedral CoII centers as indicated by SQUID magnetometry analysis in combination with X-ray photoelectron spectroscopy and infrared spectroscopy. Solvothermal treatment of 1 results in a high-nuclearity coordination cluster, [Co10(N3)2(N-n-bda)6(bza·SMe)6] (3), containing 10 virtually non-interacting high-spin CoII centers. © Copyright © 2019 Schmitz, Qiu, Glöß, van Leusen, Izarova, Nadeem, Griebel, Chiechi, Kögerler and Monakhov

Heterometallic {Fe18M6} (M = Y, Gd, Dy) Pivalate Wheels Display Solvent-Induced Polymorphism

A new series of heterometallic wheels, isolated as [Fe18M6(piv)12(Htea)18(tea)6(N3)6]\ub7n(solvent) (MIII = Y (1a, 1b), Gd (2a, 2b), and Dy (3a, 3b); Hpiv = pivalic acid, H3tea = triethanolamine), forms by the reaction of trinuclear μ3-oxo-linked or hexanuclear μ-OH-linked Fe(III) pivalate clusters with rare earth nitrates, H3tea, and azide ligands in MeOH/MeCN or EtOH/MeCN media under ultrasonic irradiation. Single-crystal X-ray diffraction showed that wheels 1a-3a prepared from MeOH/MeCN solutions crystallize in the triclinic space group P1\uaf and have Ci symmetry, whereas wheels 1b-3b received from EtOH/MeCN solution crystallize in the trigonal space group R3\uaf and have C3i symmetry. Magnetic studies reveal medium antiferromagnetic exchange interactions within the Fe3 trimeric unit (with the exchange coupling parameters of JFe3 = -13.1 cm-1 for 1a, JFe3 = -11.6 cm-1 for 1b) and weak intermolecular antiferromagnetic exchange interactions (λmf = -0.366 mol cm-3 and -0.368 mol cm-3 (zJmf = -0.19 cm-1), respectively). This leads to spin ground states of S = 5/2 for each {Fe3} unit. Substitution of diamagnetic Y(III) centers by paramagnetic Ln(III) centers (in 2a/2b by Gd(III) and in 3a/3b by Dy(III) centers) results in ferromagnetic exchange interactions between the Fe(III) and Ln(III) centers in addition to the predominant antiferromagnetic Fe\ub7\ub7\ub7Fe interactions in 1a/1b

Revisited the modelling of underground gasifier system

У даній статті висвітлені основні аспекти впровадження якісно нових підходів щодо технологій термохімічного перетворення вуглецевмісної сировини, зокрема підземної газифікації вугілля. При трансформації зв’язку «гірничодобувне підприємство → комунальне господарство» з однією направленістю виробних процесів комунальне господарство також стає постачальником енергетичної сировини. При моделюванні системи підземного газогенератора раціональні принципи та допуски при їх побудові дають можливість встановити основні закономірності процесів, а також знехтувати другорядними факторами, що впливають на її формування. Закладення термодинамічних характеристик в нульмерну постановку задачі при моделюванні системи підземного газогенератора дозволяє кількісно спрогнозувати склад та властивості складних гетерогенних, багатоелементних, мультифазних систем в широкому діапазоні температур та тисків з урахуванням хімічних і фазових перетворень. Визначення функції зміни температури (T) від співвідношення дуттьової суміші та вихідної сировини (k m ) на основі проведення термодинамічного розрахунку в нульмерній постановці дозволяє обґрунтувати параметри розповсюдження теплового поля навколо підземного газогенератора як за довжиною вогневого вибою, так і за довжиною виймального стовпа.This article highlights the main aspects of the implementation of qualitatively new approaches to technologies of thermochemical conversion of carbon-containing raw materials during underground coal gasification. With the transformation of the connection “mining company → public utility company” with one direction of production processes, utilities also become a supplier of energy raw materials. When modeling an underground gasifier system, rational principles and tolerances in their construction make it possible to establish the basic patterns of processes, as well as to neglect the secondary factors influencing its formation. Establishing thermodynamic composition and properties of complex heterogeneous, multi-element, multiphase systems in a wide range of temperatures and pressures, considering chemical and phase transformations, can be predicted in several ways. Determining the function of temperature change (T) from the ratio of blast mixture and raw material (k m ) based on thermodynamic calculation in zero-dimensional formulation allows to substantiate the parameters of thermal field propagation around the underground gasifier by the length of the combustion face and the length of the extraction column