Pyramidal Complexes Research Articles

A Kalirin missense mutation enhances dendritic RhoA signaling and leads to regression of cortical dendritic arbors across development

Normally, dendritic size is established prior to adolescence and then remains relatively constant into adulthood due to a homeostatic balance between growth and retraction pathways. However, schizophrenia is characterized by accelerated reductions of cerebral cortex gray matter volume and onset of clinical symptoms during adolescence, with reductions in layer 3 pyramidal neuron dendritic length, complexity, and spine density identified in multiple cortical regions postmortem. Nogo receptor 1 (NGR1) activation of the GTPase RhoA is a major pathway restricting dendritic growth in the cerebral cortex. We show that the NGR1 pathway is stimulated by OMGp and requires the Rho guanine nucleotide exchange factor Kalirin-9 (KAL9). Using a genetically encoded RhoA sensor, we demonstrate that a naturally occurring missense mutation in Kalrn, KAL-PT, that was identified in a schizophrenia cohort, confers enhanced RhoA activitation in neuronal dendrites compared to wild-type KAL. In mice containing this missense mutation at the endogenous locus, there is an adolescent-onset reduction in dendritic length and complexity of layer 3 pyramidal neurons in the primary auditory cortex. Spine density per unit length of dendrite is unaffected. Early adult mice with these structural deficits exhibited impaired detection of short gap durations. These findings provide a neuropsychiatric model of disease capturing how a mild genetic vulnerability may interact with normal developmental processes such that pathology only emerges around adolescence. This interplay between genetic susceptibility and normal adolescent development, both of which possess inherent individual variability, may contribute to heterogeneity seen in phenotypes in human neuropsychiatric disease.

Pyk2 suppresses contextual fear memory in an autophosphorylation-independent manner.

Clustered protocadherins (Pcdhs) are a large family of cadherin-like cell adhesion proteins that are central for neurite self-avoidance and neuronal connectivity in the brain. Their downstream nonreceptor tyrosine kinase Pyk2 (proline-rich tyrosine kinase 2, also known as Ptk2b, Cakb, Raftk, Fak2, and Cadtk) is predominantly expressed in the hippocampus. We constructed Pyk2-null mouse lines and found that these mutant mice showed enhancement in contextual fear memory, without significant change in auditory-cued and spatial-referenced learning and memory. In addition, by preparing Y402F mutant mice, we observed that Pyk2 suppressed contextual fear memory in an autophosphorylation-independent manner. Moreover, using high-throughput RNA sequencing, we found that immediate early genes, such as Npas4, cFos, Zif268/Egr1, Arc, and Nr4a1, were enhanced in Pyk2-null mice. We further showed that Pyk2 disruption affected pyramidal neuronal complexity and spine dynamics. Thus, we demonstrated that Pyk2 is a novel fear memory suppressor molecule and Pyk2-null mice provide a model for understanding fear-related disorders. These findings have interesting implications regarding dysregulation of the Pcdh‒Pyk2 axis in neuropsychiatric disorders.

Archaeological Investigation and Hazard Assessment Using Magnetic, Ground-Penetrating Radar, and GPS Tools at Dahshour Area, Giza, Egypt

An archeological study using magnetic and ground-penetrating radar methods has been performed at the Dahshour region (Giza, Egypt), where various covered structures have not been found because of the long coercion of the zone under the military specialists. Dahshour is the southern extension of the Saqqara and Giza Pyramids plateau, around 25 km south of Cairo. The area is known for its colored pyramids—the white, red, and black pyramids, and the famous Bent Pyramid. Four investigation sites were chosen around the Bent Pyramid complex. The geophysical investigation has revealed the presence of some buried structures made up of mud bricks such as tombs, mud-brick walls, causeway, and remains of an ancient temple. Numerous limestone blocks were also detected. The study indicates the possible existence of an older valley temple made up of mud bricks and confirms the existence of another causeway that led to the Nile Valley. To protect the Egyptian heritage around this vital area, a detailed computation of the current crustal stress/strain state has been performed by taking into account all the available GPS observations. Achieved results indicated that the southern and the southeastern sectors of the investigated area are currently accumulating strain, and this means that there is a possibility for future earthquakes to occur around this vital archaeological area. Buried structures are preserved by confinement in the burial materials like a large mold. However, external load or stress can still cause damage. Therefore, during excavation, the stress should be reduced to avoid wall collapsing and structure damage. Therefore, it is recommended to start excavation from the stress direction from the southern side.

Axial Redox Tuning at a Tetragonal Cobalt Center.

Square pyramidal cobalt complexes were prepared to study their multielectron redox properties. To build a stable redox-active cobalt complex, the combination of a tridentate acriPNP (acriPNP- = 4,5-bis(diisopropylphosphino)-2,7,9,9-tetramethyl-9H-acridin-10-ide) ligand with a bidentate ligand, such as 2,2'-bipyridine, 2-(o-phenyl)pyridine, biphenylene, and their analogues, was employed. In a cobalt complex having a tetragonal structure, the dx2-y2 orbital possesses an antibonding character and must remain empty for its structural integrity, while the dz2 orbital acts as a redox-active frontier molecular orbital (FMO). Tuning the redox potential of the Co(II/I) couple was successfully achieved by introducing a different axial donor. The reduction of Co(II) to Co(I) occurs at -2.6 V for a neutral donor but shifts to -3.4 V for an anionic donor. Since the redox-active dz2 orbital is close in energy to other ligand-based orbitals, multielectron redox activity is also observed. Electrochemical measurements indicate three reversible redox events within a window of -3.0-0.0 V vs Fc/Fc+ in tetrahydrofuran (THF). These redox processes are fully reversible for over 100 cycles, reflecting the electrochemical stability of these cobalt complexes. Surprisingly, the oxidation potential of the acriPNP ligand varies dramatically from +0.15 to -2.4 V, which is probably due to the cobalt contribution on the amido-based molecular orbital. The electronic structure of the cobalt complexes was examined structurally, spectroscopically, and theoretically.

Toward Frameworks with Multiple Aligned and Interactive Fe(CO)3 Rotators: Syntheses and Structures of Diiron Complexes Linked by Two trans-Diaxial α,ω-Diphosphine Ligands Ar2P(CH2)nPAr2

Reactions of (η4-benzylideneacetone)Fe(CO)3 and the α,ω-diphosphines Ar2P(CH2)nPAr2 afford the trigonal bipyramidal diiron tetraphosphorus complexes trans,trans-(CO)3Fe[Ar2P(CH2)nPAr2]2Fe(CO)3 (n/Ar = 3/Ph 3, 4/Ph 4a, 4/p-tol 4b; 56-19%). Crystal structures establish essentially parallel P-Fe-P axes, iron-iron distances of 5.894(9)-5.782(1) Å (3) and 6.403(1)-6.466(1) Å (4a,b), and van der Waals radii of 4.45 Å for the Fe(CO)3 rotators, the planes of which are offset by 0.029-1.665 Å. Analogous reactions of Ph2P(CH2)6PPh2 yield the square pyramidal monoiron complex trans-(CO)3Fe[Ph2P(CH2)6PPh2] (6', 31%), a rare case where a diphosphine spans trans basal positions (∠P-Fe-P 147.4(2)°). Both 3 and 6' exhibit two CO 13C NMR signals at room temperature, indicating slow exchange on the NMR time scale, which in the former could entail Fe(CO)3/Fe(CO)3 gearing. Under analogous conditions, 4a,b exhibit one signal. Previously reported adducts of Fe(CO)3 and Ph2P(CH2)nPPh2 are surveyed (1:1, n = 1-5; 2:2, n = 5), and the IR νC≡O band patterns and energies of all complexes analyzed with the aid of DFT calculations. The diiron complexes are preferred thermodynamically. Attention is given to limiting types of Fe(CO)3/Fe(CO)3 interactions in the diiron complexes.

Ternary antimony–chalcogen iron carbonyl complexes and their derivatives: Syntheses, structures, reactivities, and low-energy-gap characteristics

A novel series of ternary antimony–chalcogen iron carbonyl clusters, [{SbTeFe3(CO)9}{Te2Fe3(CO)9}]– (1), [{SbSeFe3(CO)9}{Se2Fe2(CO)6}]– (2), and [{SbSFe3(CO)9}{SFe3(CO)9}]– (3), were synthesized in moderate yields from reactions of [EFe3(CO)9]2– (E = Te, Se, S) with SbCl3. X-ray analyses revealed that complexes 1–3 each can be viewed as a square pyramidal geometry [SbEFe3(CO)9] (E = Te, Se, S), where the Sb atom was further coordinated with pendant cluster fragments [Te2Fe3(CO)9], [Se2Fe2(CO)6], and [SFe3(CO)9], respectively. Interestingly, the oxidation state of the Sb atom in complexes 1–3 was 0, which was evidenced by XPS and XANES. Complexes 1–3 showed high electrophilicity toward a series of metal carbonylates, which produced transmetallated products, the “spiked” square pyramidal complexes [{SbEFe3(CO)9}{M(CO)x}] [M(CO)x = Fe(CO)4, E = Te, 1-Fe; Se, 2-Fe; S, 3-Fe; M(CO)x = Cr(CO)5, Se, 2-Cr; S, 3-Cr] and the Mn(CO)4-bridged di-ESbFe3(CO)9-based clusters [{SbEFe3(CO)9}2Mn(CO)4]– (E = Se, 2-Mn; S, 3-Mn). Furthermore, the diffuse reflectance spectra showed that these ternary and quaternary antimony-chalcogenide metal carbonyl clusters possessed low energy gaps of 0.84–1.48 eV, suggesting possible electron transports within the frameworks, which was supported by crystal packings and DFT calculations.

Synthesis, Characterization and Biological Activities of Binuclear Metal Complexes of 2-Benzoylpyridine and Phenyl(Pyridin-2-yl) Methanediol Derived from 1-Phenyl-1-(Pyridin-2-yl)-N-(Pyrimidin-2-yl) Methanimine Dihydrate Schiff Base

The Schiff base, 1-phenyl-1-(pyridin-2-yl)-N-(pyrimidin-2-yl)methanimine dihydrate (L1) has been synthesized by the condensation reaction between 2-aminopyrimidine and 2-benzoylpyridine and characterized using 13C-NMR, 1H-NMR, microanalysis, FT-IR, DEPT-135, HSQC, HMBC, COZY, NOESY. The reaction of 1-phenyl-1-(pyridin-2-yl)-N-(pyrimidin-2-yl)methanimine dihydrate (L1) with salts of V(IV), Co(II) and Cu(II), however, resulted in the hydrolysis of L1 to give binuclear metal complexes of 2-benzoylpyridine (L2) and phenyl(pyridin-2-yl)methanediol (L3) which were characterized using UV-visible spectroscopy, and TGA. The single crystal x-ray structure determined for the Copper(II) complex revealed that we obtained a compound previously obtained using a different method of synthesis. The Schiff base ligand (L1) is soluble in methanol, ethanol, DMSO, acetone and DMF. Microanalysis and Spectroscopic studies indicated that binuclear metal complexes were obtained by the coordination of metal ion to 2-benzoylpyridine (L2) and phenyl(pyridin-2-yl)methanediol (L3) from the hydrolysis of L1. Spectroscopic and elemental analysis reveal the formation of square pyramidal complexes of Co(II) and Cu(II) and a square planar complex of V(IV). In vitro antibacterial and antifungal activity against three bacterial strains (Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus) and three fungal stains (Candida albicans, Candida glabrata and Candida parapsilosis) showed moderate biological activity. Antioxidant studies reveal that only the binuclear Co(II) and oxovanadium(II) complexes are potent to eliminate free radicals.

P[sbnd]C coupling reactions of pyramidal phosphinidene-bridged dimolybdenum complexes with alkynes

The new pyramidal phosphinidene-bridged complex [Mo2Cp(μ-κ1: κ1,η5-PC5H4)(η6-HMes*)(CO)2{P(OMe)3}] (2b) was prepared in situ upon reaction of the trigonal phosphinidene complex [Mo2Cp(μ – κ1: κ1, η5-PC5H4)(η6-HMes*)(CO)2] (1) with P(OMe)3. This complex underwent an unexpected Michaelis-Arbuzov-like rearrangement when dissolved in tetrahydrofuran, to give the phosphanyl-phosphonate isomer [Mo2Cp{μ – κ1: κ1, η5-P(Me)C5H4}(η6-HMes*)(CO)2{P(O)(OMe)2}] in a quantitative way. The reactions of complex 2b, and also its PMe3 analogue [Mo2Cp(μ – κ1: κ1, η5-PC5H4)(η6-HMes*)(CO)2(PMe3)] (2a), with different internal alkynes (EtCCC(O)Me and MeCCCO2Me) and terminal alkynes (HCCR; R = 4-C6H4Me, C(O)Me, CO2Me) were then investigated. These reactions proceeded in all cases rapidly at room temperature (less than 1 min) with very high regioselectivity, to give the corresponding metallacyclic products [Mo2Cp{ μ – κ2P,C: κ1P, η5-P(C5H4)CR1CR2C(O)}(η6-HMes*)(CO)(PX3)] in high yield (X = Me, OMe; R1 = Et, Me, H; R2 = C(O)Me, CO2Me, 4-C6H4Me). Spectroscopic data for these complexes indicate that they all share the same structure, further confirmed through an X-ray single crystal study on the EtCCC(O)Me derivative of compound 2b.

Antimony(III) dithiocarbamates: Crystal structures, supramolecular aggregations, DNA binding, antioxidant and antileishmanial activities

Herein, we report the synthesis and characterization of four piperazine based homoleptic antimony(III) dithiocarbamates, i.e. Sb[S2CN(CH2)4N(Bn)]3 (1), Sb[S2CN(CH2)4NCH-(Ph)2]3 (2), Sb[S2CN(CH2)4N(2-MeO-C6H4)]3 (3) and Sb[S2CN(CH2)4N(C6H4-NO2)]3.CH2Cl2 (4), by means of elemental analysis and many spectroscopic techniques, like FT-IR, NMR (1H and 13C) and single crystal XRD. The XRD data revealed a distorted trigonal antiprismatic geometry around the central antimony atom for 2 and 3, with the trigonal space groups R-3 and R3c respectively, while a distorted pentagonal pyramidal geometry was found for 4, with the triclinic space group P-1. The trigonal antiprismatic complexes (2 and 3) feature fascinating 2-D supramolecular layers, extending into 3-D networks in a stacked fashion, while for the pentagonal pyramidal complex 4, the dimensionality is lowered to linear chains. Some of these complexes (1, 2 and 4) were further checked for their biological potential (DNA binding, using UV–Visible spectroscopy, antioxidant, cytotoxic and antileishmanial). They showed moderately stronger binding with the DNA base-pairs via the intercalative mode, as suggested by hypochromism in their electronic spectra. Interestingly, complex 2 was more active than the standard drug ascorbic acid for its antioxidant action, while complex 4 showed high activity in both the cytotoxic and antileishmanial assays.

Genetics of Mexico Jamiltepec Oaxaca Mixtec Amerindians according to HLA genes

Mexican Mixtec population from coastal Jamiltepec (Oaxaca) Amerindians was studied for its HLA profile. They show genetic characteristics close to Pacific Islanders and other Mexican Isthmus Amerindians (Mazatecans, Zapotecans and Mayas). Interestingly, this coastal Oaxaca Mixtec population is genetically closer to Mazatecans than to Oaxaca Mixtec from mountains according to HLA genes. Mixtec HLA frequent extended haplotype A*24:02-B*35:14-DRB1*16:02 has been also found in Jaidukama North Colombia forest Amerindians and in Guatemala Mayas; A*24:02, DRB1*04:03, DRB1*04:04 and DRB2*16:02 are frequent alleles also common to Pacific Inhabitants. Notwithstanding, Mixtecs show deep cultural and genetic roots with Mesoamerican Amerindians and all of them probably contributed to construct Monte Alban culture around an important Pyramid Complex close to Oaxaca City.

P-N and N-Mo Bond Formation Processes in the Reactions of a Pyramidal Phosphinidene-Bridged Dimolybdenum Complex with Diazoalkanes and Organic Azides.

The reactivity of the complex [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HMes*)(PMe3)] (1) toward different diazoalkanes and organic azides was investigated. The pyramidal phosphinidene ligand in 1 displayed a strong nucleophilicity, enabling these reactions to proceed rapidly even below room temperature. Thus, 1 reacted rapidly at 253 K with different diazoalkanes N2CRR' (R,R' = H,H, Ph,Ph, H,CO2Et) to give the corresponding P:P-bridged phosphadiazadiene derivatives as major products which, however, could not be isolated. Reaction of the latter with [H(OEt2)2](BAr'4) yielded the corresponding cationic derivatives [Mo2Cp{μ-κ1P:κ1P,η5-P(NHNCRR')C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4), which were isolated in ca. 70% yield. The related species [Mo2Cp{μ-κ1P:κ1P,η5-P(NMeNCHCO2Et)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4) was isolated upon reaction of the ethyl diazoacetate derivative with MeI and subsequent anion exchange with Na(BAr'4). Reaction of 1 with aryl azides (4-C6H4Me)N3 and (4-C6H4F)N3 proceeded rapidly at low temperature to give possibly the corresponding P:P-bridged phosphaimine derivatives as major products, which could be neither isolated. Protonation of these products with [H(OEt2)2](BAr'4) gave the corresponding aminophosphanyl complexes [Mo2Cp{μ-κ1P:κ1P,η5-P(NHR)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4), isolated in ca. 75% yield. In contrast, the result of reactions of 1 with benzyl azide was strongly dependent on temperature, including the temperature in the subsequent methylation step that gave isolable cationic derivatives. By a careful choice of experimental conditions, different complexes having methylated phosphatriazadiene ligands were isolated, such as [Mo2Cp{μ-κ1P:κ1P,η5-P(NNNMeCH2Ph)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4) and the metallacyclic derivatives syn- and anti-[Mo2Cp{μ-κ2P,N:κ1P,η5-P(NMeNNCH2Ph)C5H4}(η6-HMes*)(CO)(PMe3)](BAr'4). Density functional theory calculations, along with NMR monitoring experiments, revealed that the formation of the latter products stemmed from different and kinetically favored phosphatriazadiene intermediates, thermodynamically disfavored with respect to the denitrogenation process, otherwise yielding phosphaimine derivatives.

The Bosnian Pyramid Phenomenon

The Bosnian town of Visoko has in recent years become a New Age pilgrimage site. Several formations in the landscape have been branded as ancient pyramids and tunnels. These purported monuments from bygone times are administrated by a private foundation led by the Bosnian American entrepreneur Semir Osmanagić. His claim is that the structures at Visoko were built tens of thousands of years ago by an advanced civilization that mastered a technology that enabled the concentration of healing energies. This controversial assertion is supported by invoking the supposed scientific proofs for the existence of these energies and by prominently displaying various legitimizing visual and material props. The prospect of coming into contact with the mysterious powers emanating from the site attracts numerous visitors and has led to the commodification of the pyramid and tunnel complex.

Na-Ni-H Phase Formation at High Pressures and High Temperatures: Hydrido Complexes [NiH5]3- Versus the Perovskite NaNiH3.

The Na–Ni–H system was investigated by in situ synchrotron diffraction studies of reaction mixtures NaH–Ni–H2 at around 5, 10, and 12 GPa. The existence of ternary hydrogen-rich hydrides with compositions Na3NiH5 and NaNiH3, where Ni attains the oxidation state II, is demonstrated. Upon heating at ∼5 GPa, face-centered cubic (fcc) Na3NiH5 forms above 430 °C. Upon cooling, it undergoes a rapid and reversible phase transition at 330 °C to an orthorhombic (Cmcm) form. Upon pressure release, Na3NiH5 further transforms into its recoverable Pnma form whose structure was elucidated from synchrotron powder diffraction data, aided by first-principles density functional theory (DFT) calculations. Na3NiH5 features previously unknown square pyramidal 18-electron complexes NiH53–. In the high temperature fcc form, metal atoms are arranged as in the Heusler structure, and ab initio molecular dynamics simulations suggest that the complexes are dynamically disordered. The Heusler-type metal partial structure is essentially maintained in the low temperature Cmcm form, in which NiH53– complexes are ordered. It is considerably rearranged in the low pressure Pnma form. Experiments at 10 GPa showed an initial formation of fcc Na3NiH5 followed by the addition of the perovskite hydride NaNiH3, in which Ni(II) attains an octahedral environment by H atoms. NaNiH3 is recoverable at ambient pressures and represents the sole product of 12 GPa experiments. DFT calculations show that the decomposition of Na3NiH5 = NaNiH3 + 2 NaH is enthalpically favored at all pressures, suggesting that Na3NiH5 is metastable and its formation is kinetically favored. Ni–H bonding in metallic NaNiH3 is considered covalent, as in electron precise Na3NiH5, but delocalized in the polyanion [NiH3]−.

Three‐Coordinate Rhodium Complexes in Low Oxidation States

The isolation of simultaneously low-coordinate and low-valent compounds is a timeless challenge for preparative chemists. We showcase here the preparation and full characterization of tri-coordinate rhodium(-I) and rhodium(0) complexes and a rare rhodium(I) complex. Reduction of [{Rh(μ-Cl)(IPr)(dvtms)} 2 ] ( 1 , IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazolyl-2-ylidene; dvtms = divinyltetramethyldisiloxane) with KC 8 gave the trigonal complexes K[Rh(IPr)(dvtms)] and [Rh(IPr)(dvtms)], whereas the cation [Rh(IPr)(dvtms)] + results from their oxidation or by abstraction of chloride from 1 with silver salts. The paramagnetic Rh(0) complex is a unique fully metal centered radical with the unpaired electron in the d z2 orbital. The Rh(-I) complex is an electrophile that reacts with PPh 3 with replacement of the NHC ligand, and a nucleophile, which upon reaction with [AuCl(PPh 3 )] generates the trigonal pyramidal complex [(IPr)(dvtms)Rh-Au(PPh 3 )] with a metal-metal bond between two d 10 metal centers.

Sustainability problems of the Giza pyramids

The Pyramids complex in Giza consists of three main pyramids in addition to the famous Sphinx and small queen’s pyramids. Recently, the pyramids of Cheops (Khufu), Chephren (Khafre) and Mykerinos (Menkaure) on the Giza plateau have been threatened by a rising groundwater table resulting from water leakage from the suburbs irrigation canals, and mass urbanization surrounding the Giza pyramids. The pyramids at Giza suffer from a lot of Geo-environmental and structural problems. The main objectives of this study are (1) to assess the current status of the preservation of this unique and high valuable archaeological site, (2) to analyze the various actions that cause the destruction of the pyramid complex, in particular the weathering activities and strong seismic event, and (3) to determine the geochemical and engineering properties for construction materials using different types of tools and advanced analytical and diagnostic techniques. Structural stability analysis requires good assessment of present conditions of major materials used such as stones and structural mortar. The paper shows a thorough analysis of the current condition of the Great Pyramids at Giza. The work includes a discussion and analysis of the natural character and source of the pyramids building stones, geological context, damage survey, petrographic investigation, and physical and mechanical characterization of the stones and structural mortars, by means of laboratory and in situ testing. The results are displayed, described and analyzed in the paper in the context of potential threats to the monuments. The experimental study indicates the dependence of mechanical geological properties on the physical properties and the mineral composition of the studied building materials. The physical and petrographic characteristic of the stones are related. The modeling of properties indicates a reliable relationship between the various visible pores and uniaxial compression force parameters that can be applied to predict and characterize limestone elsewhere.

РОЛЬ ЦАРЯ ПЕПИ I В СТАНОВЛЕНИИ БУДУЩЕЙ СТОЛИЦЫ ЕГИПЕТСКОГО ГОСУДАРСТВА — МЕМФИСА

There is a common point of view in Egyptology that Memphis was a state capital since the earliest times and that its protecting gods were Ptah and his spouse Sekhmet. Arguing this concept, the author tries to find the reason why a pyramid city of Pepi I — Mennefer — became a core of the future capital. The main conclusion is following: Constructing his pyramid complex, Pepi I probably included into it a cult center of Habes where Bastet and Imhotep, a high priest of Ra, were worshiped. Imhotep, a companion of the king Djoser, was known as a priest and charmer who tamed the fiery forces of Sirius associated with Bastet, after which the great drought was over. To commemorate this, New Year celebration and the first sun calendar were established. Imhotep’s tomb became an important cult place, where ceremonies important for surviving of the Egyptian state were conducted. In the second half of the Old Kingdom period the Nile started to flood much less, which led to the decline of agriculture. Thus, the role of the cult center of Habes and Imhotep grew greatly. By including Habes, Pepi protected the dominion of his pyramid city from negative influence of Bastet and decreased flooding. The fact that Mennefer was a successor of the aforementioned cult center determined its capital functions in future.

From Saqqara to Brussels: A Head from a Sixth Dynasty Prisoner Statue in the Musees Royaux d’Art et d’Histoire

Six of the late Old Kingdom pharaohs erected statues of foreign bound prisoners in their pyramid complexes. These statues, which are known today as prisoner statues, are unique in being free-standing, nearly life-size, limestone depictions of the king’s enemies. An unpublished head in the Musées Royaux d’Art et d’Histoire in Brussels once belonged to such a statue. Its facial features, which are executed in the so-called Second Style or the late Old Kingdom style, most closely resemble those from Sixth Dynasty prisoner statues, indicating that the Brussels head most likely came from a Sixth Dynasty pyramid complex. Moreover, a number of factors tentatively suggest that this complex was probably that of Pepi II.

„Z żarów nad Nilem w ogień rewolucji nad Wisłą”. Izydor Kajetan Wysłouch (1869–1937) i jego działalność społeczna

“From the Heats by Nile to the Fire of Revolution by Vistula”. Izydor Kajetan Wysłouch (1869–1973) and His Social Activity The paper reminds the profile of a respected religious reformer and social activist whose life was also connected to Egypt. From 1902 to 1904, due to ill-health, he visited Egypt twice as he required climatotherapy. At that time he stayed in Helwan, a popular resort near Cairo. During his treatment, he was probably residing in Wanda Bilińska’s guesthouse, where residents from the territories of former-day Poland met. The stay in Egypt made a huge impression on Wysłouch. An ample evidence of his fascination with heritage and monuments of ancient Egypt is the neatly published volume, issued soon after the author’s return to Poland, titled From the Land of Ruins (Warsaw 1906); what is also interesting is its graphic design, using Egyptian motives, created by Franciszek Siedlecki (1867–1934). The volume, containing the author’s reflections on existence and prose poetry, signals the state of his soul, which was filled with loneliness and bitter sadness. Its content also suggests that the author had visited most of the country, from the Giza Pyramid Complex to the city of Aswan. Egypt influenced him to such a great degree that he called the country his second homeland. He also took his pen-name “Szech” (ar. Sheikh) at that time. Having returned to his motherland, Wysłouch became a keen supporter of working-class protests (1905). He also strongly backed the reforms in the Ethical and Social Teachings of the Church; he published numerous brochures in which he described an utopian programme that would connect Christianity with Communism and Polish patriotism; he decided to leave Church in 1908. After Poland regained its independence in 1918, Wysłouch, as a public servant, played a vital role in organising and introducing the system of public disability pensions and retirement insurance in the reborn Poland.

Chirality Control in Crystalline Ni(II) Complexes of Thiophosphorylated Thioureas

Chirality control over the formation of Ni(II) complexes with chiral thiophosphorylated thioureas was achieved via breaking the symmetry of nickel coordination geometry by the introduction of the pyridine ligand, while centrosymmetric meso-complexes are formed from racemic ligands in case of square-planar nickel coordination. Centrosymmetric heterochiral arrangement is observed in crystals of ligands themselves through N–H⋅⋅⋅S hydrogen bonds in intermolecular dimers. Molecular homochirality in tetragonal pyramidal complexes is further transferred to supramolecular homochiral arrangement via key–lock steric interactions.

PCM 2019 Preface

The 6th Global Conference on Polymer and Composite Materials (PCM 2019) was held from July 8 -11, 2019 in Bangkok, Thailand. The conference, with 165 participants, had a technical program consisting of 5 international keynote speakers, 87 oral presentations, and a poster session with 48 works. The conference had 7 oral parallel sessions with dedicated selected subjects related to Polymers and Composite Materials.The present issue of IOP Conference Series: Materials Science and Engineering (MSE) records the proceedings of PCM 2019 and contains 48 specially selected manuscripts submitted to the conference. The electronic submission and handling of manuscripts via the conference website, including the selection of reviewers and evaluation of manuscripts, were identical to the procedures applied to manuscripts submitted as regular contributions for international per-reviewed publications.The organization of this conference and the preparation of proceedings volume would have been impossible without the tremendous efforts and dedication of many individuals, especially from Ms. Yoko Ye, who oversaw the organization of the conference and the program, and a large team of reviewers with their timely submission of quality reports. We express our sincere thanks to all authors and presenters for their contributions. We also thank very much all our sponsors for their generous support, specially to Rangsit University.The 7th Global Conference on Polymer and Composite Materials (PCM 2020) will be held during August 17th-20th, 2019, in the city of Cairo, Egypt. Located near the Nile Delta, the land composing the present-day Modern Cairo was the site of ancient national capitals whose remnants remain visible in parts of Old Cairo. The city’s metropolitan area is one of the largest in Africa, and is associated with ancient Egypt, as the famous Giza pyramid complex and the ancient city of Memphis are located in its geographical area. Today, Greater Cairo has the largest number of educational schools, and higher learning institutes among other cities of Egypt. The great majority of publishing houses and media outlets and nearly all film studios are there, as are half of the nation’s universities. Cairo accounts for 11% of Egypt’s population and 22% of its economy. Cairo also has long been a center of the region’s political and cultural life, and is titled “the city of a thousand minarets” for its preponderance of Islamic architecture. Some of landmarks of Cairo include Tahrir Square, the Museum of Egyptian Antiquities, the Cairo Tower, and the area of Old Cairo. All participants are welcome to the renewed and vibrant PCM 2020! More information will be available at the conference website: http://www.cpcmconf.org.Prof. Dr. Esteban BroitmanGeneral Chairman PCM2019SKF Research & Technology Development (RTD), Netherlands, August 2019