Associative Pavlovian conditioning leads to an increase in spinophilin-immunoreactive dendritic spines in the lateral amygdala

Changes in dendritic spine number and shape are believed to reflect structural plasticity consequent to learning. Previous studies have strongly suggested that the dorsal subnucleus of the lateral amygdala is an important site of physiological plasticity in Pavlovian fear conditioning. In the present study, we examined the effect of auditory fear conditioning on dendritic spine numbers in the dorsal subnucleus of the lateral amygdala using an immunolabelling procedure to visualize the spine-associated protein spinophilin. Associatively conditioned rats that received paired tone and shock presentations had 35% more total spinophilin-immunoreactive spines than animals that had unpaired stimulation, consistent with the idea that changes in the number of dendritic spines occur during learning and account in part for memory.

Distribution of NMDA and AMPA receptor subunits at thalamo-amygdaloid dendritic spines

Synapses onto dendritic spines in the lateral amygdala formed by afferents from the auditory thalamus represent a site of plasticity in Pavlovian fear conditioning. Previous work has demonstrated that thalamic afferents synapse onto LA spines expressing glutamate receptor (GluR) subunits, but the GluR subunit distribution at the synapse and within the cytoplasm has not been characterized. Therefore, we performed a quantitative analysis for α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits GluR2 and GluR3 and N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2B by combining anterograde labeling of thalamo-amygdaloid afferents with postembedding immunoelectron microscopy for the GluRs in adult rats. A high percentage of thalamo- amygdaloid spines was immunoreactive for GluR2 (80%), GluR3 (83%), and NR1 (83%), while a smaller proportion of spines expressed NR2B (59%). To compare across the various subunits, the cytoplasmic to synaptic ratios of GluRs were measured within thalamo-amygdaloid spines. Analyses revealed that the cytoplasmic pool of GluR2 receptors was twice as large compared to the GluR3, NR1, and NR2B subunits. Our data also show that in the adult brain, the NR2B subunit is expressed in the majority of in thalamo-amygdaloid spines and that within these spines, the various GluRs are differentially distributed between synaptic and non-synaptic sites. The prevalence of the NR2B subunit in thalamo-amygdaloid spines provides morphological evidence supporting its role in the fear conditioning circuit while the differential distribution of the GluR subtypes may reflect distinct roles for their involvement in this circuitry and synaptic plasticity.

Localization of glucocorticoid receptors at postsynaptic membranes in the lateral amygdala

Glucocorticoids, released in high concentrations from the adrenal cortex during stressful experiences, bind to glucocorticoid receptors in nuclear and peri-nuclear sites in neuronal somata. Their classically known mode of action is to induce gene promoter receptors to alter gene transcription. Nuclear glucocorticoid receptors are particularly dense in brain regions crucial for memory, including memory of stressful experiences, such as the hippocampus and amygdala. While it has been proposed that glucocorticoids may also act via membrane bound receptors, the existence of the latter remains controversial. Using electron microscopy, we found glucocorticoid receptors localized to non-genomic sites in rat lateral amygdala, glia processes, presynaptic terminals, neuronal dendrites, and dendritic spines including spine organelles and postsynaptic membrane densities. The lateral nucleus of the amygdala is a region specifically implicated in the formation of memories for stressful experiences. These newly observed glucocorticoid receptor immunoreactive sites were in addition to glucocorticoid receptor immunoreactive signals observed using electron and confocal microscopy in lateral amygdala principal neuron and GABA neuron soma and nuclei, cellular domains traditionally associated with glucocorticoid immunoreactivity. In lateral amygdala, glucocorticoid receptors are thus also localized to non-nuclear-membrane translocation sites, particularly dendritic spines, where they show an affinity for postsynaptic membrane densities, and may have a specialized role in modulating synaptic transmission plasticity related to fear and emotional memory.

Molecular characterization of "Candidatus Parilichlamydia carangidicola," a novel Chlamydia-like epitheliocystis agent in yellowtail kingfish, Seriola lalandi (Valenciennes), and the proposal of a new family, "Candidatus Parilichlamydiaceae" fam. nov. (order Chlamydiales).

Three cohorts of farmed yellowtail kingfish (Seriola lalandi) from South Australia were examined for Chlamydia-like organisms associated with epitheliocystis. To characterize the bacteria, 38 gill samples were processed for histopathology, electron microscopy, and 16S rRNA amplification, sequencing, and phylogenetic analysis. Microscopically, the presence of membrane-enclosed cysts was observed within the gill lamellae. Also observed was hyperplasia of the epithelial cells with cytoplasmic vacuolization and fusion of the gill lamellae. Transmission electron microscopy revealed morphological features of the reticulate and intermediate bodies typical of members of the order Chlamydiales. A novel 1,393-bp 16S chlamydial rRNA sequence was amplified from gill DNA extracted from fish in all cohorts over a 3-year period that corresponded to the 16S rRNA sequence amplified directly from laser-dissected cysts. This sequence was only 87% similar to the reported "Candidatus Piscichlamydia salmonis" (AY462244) from Atlantic salmon and Arctic charr. Phylogenetic analysis of this sequence against 35 Chlamydia and Chlamydia-like bacteria revealed that this novel bacterium belongs to an undescribed family lineage in the order Chlamydiales. Based on these observations, we propose this bacterium of yellowtail kingfish be known as "Candidatus Parilichlamydia carangidicola" and that the new family be known as "Candidatus Parilichlamydiaceae."

The molecular structure of the vanadate mineral mottramite [PbCu(VO4)(OH)] from Tsumeb, Namibia – a vibrational spectroscopic study

We have studied a mineral sample of mottramite PbCu(VO4)(OH) from Tsumeb, Namibia using a combination of scanning electron microscopy with EDX, Raman and infrared spectroscopy. Chemical analysis shows principally the elements V, Pb and Cu. Ca occurs as partial substitution of Pb as well as P and As in substitution to V. Minor amounts of Si and Cr were also observed. The Raman band of mottramite at 829 cm-1, is assigned to the ν1 symmetric (VO-4) ) stretching mode. The complexity of the spectra is attributed to the chemical composition of the Tsumeb mottramite. The ν3 antisymmetric vibrational mode of mottramite is observed as very low intensity bands at 716 and 747 cm-1. The series of Raman bands at 411, 439, 451 cm-1 and probably also the band at 500 cm-1 are assigned to the (VO-4) ν2 bending mode. The series of Raman bands at 293, 333 and 366 cm-1 are attributed to the (VO-4) ) ν4 bending modes. The ν3, ν3 and ν4 regions are complex for both minerals and this is attributed to symmetry reduction of the vanadate unit from Td to Cs.

Organo-LDH synthesized via tricalcium aluminate hydration in the present of Na-dodecylbenzenesulfate aqueous solution and subsequent investigated by near-infrared and mid-infrared

Na-dodecylbenzenesulfate (SDBS), a natural anionic surfactant, has been successfully intercalated into a Ca based LDH host structure during tricalcium aluminate hydration in the presence of SDBS aqueous solution (CaAl-SDBS-LDH). The resulting product was characterized by powder X-ray diffraction (XRD), mid-infrared (MIR) spectroscopy combined with near-infrared (NIR) spectroscopy technique, thermal analysis (TG–DTA) and scan electron microscopy (SEM). The XRD results revealed that the interlayer distance of resultant product was expanded to 30.46 Å. MIR combined with NIR spectra offered an effective method to illustrate this intercalation. The NIR spectra (6000–5500 cm−1) displayed prominent bands to expound SDBS intercalated into hydration product of C3A. And the bands around 8300 cm−1 were assigned to the second overtone of the first fundamental of CH stretching vibrations of SDBS. In addition, thermal analysis showed that the dehydration and dehydroxylation took place at ca. 220 °C and 348 °C, respectively. The SEM results appeared approximately hexagonal platy crystallites morphology for CaAl-SDBS-LDH, with particle size smaller and thinner.

Raman spectroscopy of the arsenate minerals maxwellite and in comparison with tilasite

Maxwellite NaFe3+(AsO4)F is an arsenate mineral containing fluoride and forms a continuous series with tilasite CaMg(AsO4)F. Both maxwellite and tilasite form a continuous series with durangite NaAl3+(AsO4)-F. We have used the combination of scanning electron microscopy with EDS and vibrational spectroscopy to chemically analyse the mineral maxwellite and make an assessment of the molecular structure. Chemical analysis shows that maxwellite is composed of Fe, Na and Ca with minor amounts of Mn and Al. Raman bands for tilasite at 851 and 831 cm�1 are assigned to the Raman active m1 symmetric stretching vibration (A1) and the Raman active triply degenerate m3 antisymmetric stretching vibration (F2). The Raman band of maxwellite at 871 cm�1 is assigned to the m1 symmetric stretching vibration and the Raman band at 812 cm�1 is assigned to the m3 antisymmetric stretching vibration. The intense Raman band of tilasite at 467 cm�1 is assigned to the Raman active triply degenerate m4 bending vibration (F2). Raman band at 331 cm�1 for tilasite is assigned to the Raman active doubly degenerate m2 symmetric bending vibration (E). Both Raman and infrared spectroscopy do not identify any bands in the hydroxyl stretching region as is expected.

A vibrational spectroscopic study of the phosphate mineral lulzacite Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10

The mineral lulzacite from Saint-Aubin des Chateaux mine, France, with theoretical formula Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10 has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Chemical analysis shows a Sr, Fe, Al phosphate with minor amounts of Ga, Ba and Mg. Raman spectroscopy identifies an intense band at 990 cm�1 with an additional band at 1011 cm�1. These bands are attributed to the PO3� 4 m1 symmetric stretching mode. The m3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm�1 are assigned to the m3 antisymmetric stretching vibrations of PO3� 4 and the HOPO2� 3 units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of lulzacite. The series of Raman bands at 567, 582, 601, 644, 661, 673 and 687 cm�1 are assigned to the PO3� 4 m2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm�1 are attributed to the PO3� 4 and HOPO2� 3 m4 bending modes. No Raman bands of lulzacite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm�1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm�1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral lulzacite.

A vibrational spectroscopic study of the silicate mineral inesite Ca2(Mn,Fe)₇Si10O28(OH)⋅5H2O

We have studied the hydrated hydroxyl silicate mineral inesite of formula Ca2(Mn,Fe)7Si10O28(OH)⋅5H2O using a combination of scanning electron microscopy with EDX and Raman and infrared spectroscopy. SEM analysis shows the mineral to be a pure monomineral with no impurities. Semiquantitative analysis shows a homogeneous phase, composed by Ca, Mn2+, Si and P, with minor amounts of Mg and Fe. Raman spectrum shows well resolved component bands at 997, 1031, 1051, and 1067 cm-1 attributed to a range of SiO symmetric stretching vibrations of [Si10O28] units. Infrared bands found at 896, 928, 959 and 985 cm-1 are attributed to the OSiO antisymmetric stretching vibrations. An intense broad band at 653 cm-1 with shoulder bands at 608, 631 and 684 cm-1 are associated with the bending modes of the OSiO units of the 6- and 8-membered rings of the [Si10O28] units. The sharp band at 3642 cm-1 with shoulder bands at 3612 and 3662 cm-1 are assigned to the OH stretching vibrations of the hydroxyl units. The broad Raman band at 3420 cm-1 with shoulder bands at 3362 and 3496 cm-1 are assigned to the water stretching vibrations. The application of vibrational spectroscopy has enabled an assessment of the molecular structure of inesite to be undertaken.

The molecular structure of the phosphate mineral beraunite Fe2+Fe⅗+(PO4)4(OH)5⋅4H2O– A vibrational spectroscopic study

The mineral beraunite from Boca Rica pegmatite in Minas Gerais with theoretical formula Fe2+Fe5 3+(PO4)4(OH)5⋅4H2O has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Raman spectroscopy identifies an intense band at 990 cm-1 and 1011 cm-1. These bands are attributed to the PO4 3- v, symmetric stretching mode. The m3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm-1 are assigned to the m3 antisymmetric stretching vibrations of PO4 3- and the HOPO3 2- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of beraunite. The series of Raman bands at 567, 582,601, 644, 661, 673, and 687 cm-1 are assigned to the PO4 3- v2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm-1 are attributed to the PO4 3- and OPO3 2- v4 bending modes. No Raman bands of beraunite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral beraunite.

Gas sensing of ruthenium implanted tungsten oxide thin films

Different amounts of Ru were implanted into thermally evaporated WO3 thin films by ion implantation. The films were subsequently annealed at 600oC for 2 hours in air to remove defects generated during the ion implantation. The Ru concentrations of four samples have been quantified by Rutherford Backscattering Spectrometry as 0.8, 5.5, 9 and 11.5 at%. The un-implanted WO3 films were highly porous but the porosity decreased significantly after ion implantation as observed by Transmission Electron Microscopy and Scanning Electron Microscopy. The thickness of the films also decreased with increasing Ru-ion dose, which is mainly due to densification of the porous films during ion implantation. From Raman spectroscopy two peaks at 408 and 451 cm-1 (in addition to the typical vibrational peaks of the monoclinic WO3 phase) associated with Ru were observed. Their intensity increased with increasing Ru concentration. X-Ray Photoelectron Spectroscopy showed a metallic state of Ru with binding energy of Ru 3d5/2 at 280.1 eV. This peak position remained almost unchanged with increasing Ru concentration. The resistances of the Ru-implanted films were found to increase in the presence of NO2 and NO with higher sensor response to NO2. The effect of Ru concentration on the sensing performance of the films was not explicitly observed due to reduced film thickness and porosity with increasing Ru concentration. However, the results indicate that the implantation of Ru into WO3 films with sufficient film porosity and film thickness can be beneficial for NO2 sensing at temperatures in the range of 250°C to 350°C.

Comparative study of photocatalytic performance of titanium oxide spheres assembled by nanorods, nanoplates and nanosheets

TiO2 spheres assembled by nanorods, nanoplates and nanosheets were fabricated by facile hydrothermal/solvothermal methods. The three samples were thoroughly characterised by scanning electron microscopy, X-ray diffraction, the Brunauer–Emmett–Teller method and UV spectroscopy. The surface area of spheres assembled by nanosheets was 83.9 m2g–1, which is larger than that obtained for nanorods (10.8 m2g–1) and nanoplates (6.31 m2g–1). Their photocatalytic performance was evaluated in terms of the decomposition rate of methyl orange in these three samples under UV irradiation. The best photoactivity was observed in the samples constructed from nanosheets.

Preparation of mesoporous bioglass coated zirconia scaffold for bone tissue engineering

Porous yttria-stabilized zirconia (YSZ) has been regarded as a potential candidate for bone substitute due to its high mechanical strength. However, porous YSZ is biologically inert to bone tissue. It is therefore necessary to introduce bioactive coatings onto the walls of the porous structures to enhance its bioactivity. In this study, porous YSZ scaffolds were prepared using a replication technique and then coated with mesoporous bioglass due to its excellent bioactivity. The microstructures were examined using scanning electron microscopy and the mechanical strength was evaluated via compression test. The biocompatibility and bioactivity were also evaluated using bone marrow stromal cell (BMSC) proliferation test and simulated body fluid test.

Residual stresses in rail-ends from the in-service insulated rail joints using neutron diffraction

Insulated rail joints (IRJs) are an integral part of the rail track signaling system and pose significant maintenance and replacement costs due to their low and fluctuating service lives. Failure occurs mainly in rail head region, bolt- holes of fishplates and web-holes of the rails. Propagation of cracks is influenced by the evolution of internal residual stresses in rails during rail manufacturing (hot-rolling, roller-straightening, and head-hardening process), and during service, particularly in heavy rail haul freight systems where loads are high. In this investigation, rail head accumulated residual stresses were analysed using neutron diffraction at the Australian Nuclear Science and Technology Organisation (ANSTO). Two ex-service two head-hardened rail joints damaged under different loading were examined and results were compared with those obtained from an unused rail joint reference sample in order to differentiate the stresses developed during rail manufacturing and stresses accumulated during rail service. Neutron diffraction analyses were carried out on the samples in longitudinal, transverse and vertical directions, and on 5mm thick sliceed samples cut by Electric Discharge Machining (EDM). For the rail joints from the service line, irrespective of loading conditions and in-service times, results revealed similar depth profiles of stress distribution. Evolution of residual stress fields in rails due to service was also accompanied by evidence of larger material flow based on reflected light and scanning electron microscopy studies. Stress evolution in the vicinity of rail ends was characterised by a compressive layer, approximately 5 mm deep, and a tension zone located approximately 5- 15mm below the surfaces. A significant variation of d0 with depth near the top surface was detected and was attributed to decarburization in the top layer induced by cold work. Stress distributions observed in longitudinal slices of the two different deformed rail samples were found to be similar. For the undeformed rail, the stress distributions obtained could be attributed to variations associated with thermo-mechanical history of the rail.

Investigation on mechanical behaviour of AM60 magnesium alloys

Purpose: In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy. The effects of environmental temperature and loading rates on impact and tension behavior of the alloy were also investigated. Design/methodology/approach: The tests were conducted using an Instron universal testing machine. The loading speed was changed from 1 mm/min to 300 mm/min to gain a better understanding of the effect of strain rate. To understand the failure behavior of this alloy at different environmental temperatures, Charpy impact test was conducted in a range of temperatures (-40~35°C). Plane strain fracture toughness (KIC) was evaluated using compact tension (CT) specimen. To gain a better understanding of the failure mechanisms, all fracture surfaces were observed using scanning electron microscopy (SEM). In addition, fatigue behavior of this alloy was estimated using tension test under tension-tension condition at 30 Hz. The stress amplitude was selected in the range of 20~50 MPa to obtain the S-N curve. Findings: The tensile test indicated that the mechanical properties were not sensitive to the strain rates applied (3.3x10-4~0.1) and the plastic deformation was dominated by twining mediated slip. The impact energy is not sensitive to the environmental temperature. The plane strain fracture toughness and fatigue limit were evaluated and the average values were 7.6 MPa.m1/2 and 25 MPa, respectively. Practical implications: Tested materials AM60 Mg alloy can be applied among others in automotive industry aerospace, communication and computer industry. Originality/value: Many investigations have been conducted to develop new Mg alloys with improved stiffness and ductility. On the other hand, relatively less attention has been paid to the failure mechanisms of Mg alloys, such as brittle fracture and fatigue, subjected to different environmental or loading conditions. In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy.