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This work is focused on the evaluation of the free volume space and the concentration of nano-sized cavities trapped in Fe2O3 mixed lead zirconium silicate glass ceramics using positron annihilation lifetime spectroscopy (PALS) studies with 22Na (0.1MBq) positron source. Such imperfections are anticipated to have strong bearing on physical characteristics of the glass ceramic. The glasses of a particular composition viz., 36PbO–4ZrO2–(60–x)SiO2: xFe2O3 (0 ≤ x ≤ 0.5 in the intervals of 0.1) were synthesized by traditional melting and quenching techniques. The lifetime of the positrons measured in these samples is found to be strongly reliant on the content of Fe2O3. The results have suggested the increased fraction of free volume imperfections (fv), and radius of the cavities (R) with increase of Fe2O3 content from 0.2 to 0.5 mol%. The spectroscopic studies of these samples indicated that iron ions predominantly existed in Fe3+ state and occupied octahedral positions with FeO6 structural units, acted as modifiers and induced several imperfections. The estimated maximal concentration of imperfections in the glass ceramic sample F5 by PALS studies is attributed to such reasons. The inferences drawn from PALS studies regarding the concentration of defects in these samples are found to be in agreement with the results of third harmonic generation (THG) studies and conductivity studies.

Fourier transform infrared (FT-IR) spectroscopy (IR Biotyper; Bruker) allows highly discriminatory fingerprinting of closely related bacterial strains. In this study, FT-IR spectroscopy-based capsular typing of Streptococcus pneumoniae was validated as a rapid, cost-effective, and medium-throughput alternative to the classical phenotypic techniques. A training set of 233 strains was defined, comprising 34 different serotypes and including all 24 vaccine types (VTs) and 10 non-vaccine types (NVTs). The acquired spectra were used to (i) create a dendrogram where strains clustered together according to their serotypes and (ii) train an artificial neural network (ANN) model to predict unknown pneumococcal serotypes. During validation using 153 additional strains, we reached 98.0% accuracy for determining serotypes represented in the training set. Next, the performance of the IR Biotyper was assessed using 124 strains representing 59 non-training set serotypes. In this setting, 42 of 59 serotypes (71.1%) could be accurately categorized as being non-training set serotypes. Furthermore, it was observed that comparability of spectra was affected by the source of the Columbia medium used to grow the pneumococci and that this complicated the robustness and standardization potential of FT-IR spectroscopy. A rigorous laboratory workflow in combination with specific ANN models that account for environmental noise parameters can be applied to overcome this issue in the near future. The IR Biotyper has the potential to be used as a fast, cost-effective, and accurate phenotypic serotyping tool for S. pneumoniae. ispartof: JOURNAL OF CLINICAL MICROBIOLOGY vol:60 issue:7 ispartof: location:United States status: published

Thermodynamical properties of the superconducting state in metallic hydrogen were determined on the basis of the model of two compressed hydrogen planes. We took into account both the on-site and the inter-site electronic correlations (U and K), as well as the relevant non-conventional electron-phonon coupling functions (gU and gK). We proved, within the Eliashberg formalism, that the maximum value of the critical temperature of transition into the superconducting state is about 200 K for the harmonic approximation, and about 84 K for the Morse anharmonic approximation. Omission of the electronic correlations results in a considerable overstatement of the TC value. On the other hand, the TC value is remarkably understated if the non-conventional interactions are disregarded. Other thermodynamic quantities, such as the order parameter, the jump in the specific heat value, the thermodynamic critical field, and the upper critical field, take the values for which the non-dimensional ratios RΔ, RC, RH and RH2 do not differ substantially from the predictions of the BCS theory.

Thermodynamic parameters of the $\rm LaH_{10}$ superconductor were an object of our interest. $\rm LaH_{10}$ is characterised by the highest experimentally observed value of the critical temperature: $T^{a}_{C}=215$~K ($p_{a}=150$~GPa) and $T^{b}_{C}=260$~K ($p_{b}=190$~GPa). It belongs to the group of superconductors with a~strong electron--phonon coupling ($��_{a}\sim 2.2$ and $��_{b}\sim 2.8$). We calculated thermodynamical parameters of this superconductor and found that the values of the order parameter, the thermodynamic critical field, and the specific heat differ significantly from the values predicted by the conventional BCS theory. Due to the specific structure of the Eliashberg function for the hydrogenated compounds, the qualitative analysis suggests that the superconductors of the ${\rm La_��X_{1-��}H_{10}}$--type (LaXH--type) structure, where ${\rm X}\in\{{\rm Sc},{\rm Y}\}$, would exhibit significantly higher critical temperature than $T_{C}$ obtained for $\rm LaH_{10}$. In the case of LaScH we came to the following assessments: $T^{a}_{C}\in\left$~K and $T^{b}_{C}\in\left$~K, while the results for LaYH were: $T^{a}_{C}\in\left$~K and $T^{b}_{C}\in\left$~K., 6 pages, 5 figures

The neurotoxin 6-hydroxydopamine (6-OHDA), following pretreatment with the norepinephrine transport inhibitor desipramine, selectively destroys dopaminergic neurons. When given to rats, neonatal 6-OHDA (n6-OHDA) crosses the blood-brain barrier to destroy 90-99% of dopaminergic nerves in pars compacta substantia nigra (SNpc). The n6-OHDA-lesioned rat is posed as a reasonable animal model for PD: (a) the magnitude of dopaminergic neuronal destruction is expansive, (b) mapping of dopaminergic denervation has been defined, (c) effects on dopamine (DA) receptor alterations have been elucidated (d) as well as changes in receptor sensitivity status, (e) reactive sprouting of serotoninergic innervation (i.e. hyperinnervation) has been mapped, and (f) interplay between serotoninergic and dopaminergic systems is characterized. (g) A broad range of locomotor and stereotyped behaviors has been assessed and (h) large numbers of neurochemical assessments have been attained. (i) n6-OHDA-lesioned rats survive 6-OHDA lesioning and (j) the rat is behaviorally indistinguishable from controls. Dopaminergic destruction in early ontogeny rather in adulthood is a 'treatment liability' of this model, yet other animal models have liability issues of a serious nature-the initial one being use of a neurotoxin to produce the animal model of PD. The n6-OHDA-lesioned rat is proposed as a PD model for its value in associating the SNpc dopaminergic lesion with behavioral outcomes, also for replicability of dopaminergic destruction, and the accompanying neuronal adaptations and interplay between neuronal phenotypes in brain-which provide a means to better define and understand the range of deficits and neuronal adaptations that are likely to occur in human PD.

We consider two PT-symmetric models, consisting of two or three single-mode cavities. In both models, the cavities are coupled to each other by linear interactions, forming a linear chain. Additionally, the first and last of such cavities interact with an environment. Since the models are PT-symmetric, they are described by non-Hermitian Hamiltonians that, for a specific range of system parameters, possess real eigenvalues. We show that in the models considered in the article, the steering generation process strongly depends on the coupling strengths and rates of the gains/losses in energy. Moreover, we find the values of parameters describing the system for which the steering appears.

The airborne fungus Aspergillus fumigatus poses a serious health threat to humans by causing numerous invasive infections and a notable mortality in humans, especially in immunocompromised patients. Mould-active azoles are the frontline therapeutics employed to treat aspergillosis. The global emergence of azole-resistant A. fumigatus isolates in clinic and environment, however, notoriously limits the therapeutic options of mould-active antifungals and potentially can be attributed to a mortality rate reaching up to 100 %. Although specific mutations in CYP51A are the main cause of azole resistance, there is a new wave of azole-resistant isolates with wild-type CYP51A genotype challenging the efficacy of the current diagnostic tools. Therefore, applications of whole-genome sequencing are increasingly gaining popularity to overcome such challenges. Prominent echinocandin tolerance, as well as liver and kidney toxicity posed by amphotericin B, necessitate a continuous quest for novel antifungal drugs to combat emerging azole-resistant A. fumigatus isolates. Animal models and the tools used for genetic engineering require further refinement to facilitate a better understanding about the resistance mechanisms, virulence, and immune reactions orchestrated against A. fumigatus. This review paper comprehensively discusses the current clinical challenges caused by A. fumigatus and provides insights on how to address them. AA, RGR, and DSP were supported by NIH AI 109025. MH was supported by NIH UL1TR001442. AC was supported by the Fundação para a Ciência e a Tecnologia (FCT) (CEECIND/03628/2017 and PTDC/MED GEN/28778/2017). Additional support was provided by FCT (UIDB/50026/2020 and UIDP/50026/2020), the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) (NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-000023), the European Union's Horizon 2020 Research and Innovation programme under grant agreement no. 847507, and the “la Caixa” Foundation (ID 100010434) and FCT under the agreement LCF/PR/HP17/52190003. DJA was supported by CF Trust Strategic Research Centre TrIFIC (SRC015), Wellcome Trust Collaborative Award 219551/Z/19/Z and the NIHR Centre for Antimicrobial Optimisation. Peer Reviewed "Article signat per 21 autors/es: A.Arastehfar, A.Carvalho, J.Houbraken, L.Lombardi, R.Garcia-Rubio, J.D.Jenks, O.Rivero Menendez, R. Aljohani, I.D.Jacobsen, J.Berman, N.Osherov, M.T.Hedayati, M.Ilkit, D.James-Armstrong, T.Gabaldón, J.Meletiadis, M.Kostrzewa, W.Pan, C.Lass-Flörl, D.S.Perlin, M.Hoenigl"

Earlier, we have reported the results of quantitative studies on structural and a variety of physical properties (that include non-linear optical, piezo-optical and electrical characteristics) of Na2O-Sb2O3:Ag2O/Au2O3 glass ceramics. In continuation of these studies, this part of the investigation is devoted to estimate the concentration of the defects and the free volume space (up to the nano scale) entrenched in the titled glass ceramics (as functions of the concentrations of dopant noble metal ions) by means of positron annihilation lifetime spectroscopy (PAS) technique. Such defects are predicted to have tremendous influence on above mentioned physical properties of these glass ceramics. Glasses of the composition (40-x) Na2O–60 Sb2O3: xAg2O/Au2O3 (x = 0.025–0.15 mol% for Ag2O glasses and x = 0.025–0.1 mol% for Au2O3 glasses) were prepared by melt quenching and subsequent heat-treatment for prolonged times. PAS studies were performed using 22Na positron source of strength 0.1 MBq. The results of these studies indicated significant influence of the concentrations Ag2O and Au2O3 on positron annihilation lifetime in the samples. In both the series of the samples, the third component of intensity, I3 (among the three components) is observed to be the longest-lived component. Further, for Ag2O doped glass ceramics, the value of I3 is found to be the maximal, whereas the life time component τ3, concentration of nano sized free volume defects and their volume fraction (fv), cavity radius (R) are found to be minimal for the samples doped with 0.1 mol% Ag2O and for the Au2O3 doped glass ceramics, these parameters have exhibited continuous decreasing trend with increase of Au2O3 concentration. Such decrease of defect concentration is attributed to the increasing degree of participation of antimony ions in the glass network forming with Sb(V)O4 structural units. Overall, information obtained regarding the dependence of free volume defect concentration on the contents of dopants is well in accordance with conclusions drawn from various macroscopic properties of these materials presented in our earlier reports.

This investigation is devoted to study the influence of CoO concentration on dielectric characteristics of a heavy metal oxide glass system viz., lead bismuth silicate. The auxiliary spectroscopic studies have indicated progressive increase of the fraction of tetrahedral (Td) divalent cobalt ions in the glass structure as the concentration of CoO is gradually raised. Dielectric parameters measured in the wide range of frequencies and temperatures showed a lowering trend with CoO content; such result is attributed to the growing presence of Co2+ (Td) ions that participate in the glass structure that would obstruct the migration of charge carriers towards electrodes. Electric moduli variations have exhibited dipolar relaxation effects. Co2+ (Oh) and Bi3+ ions were predicted to be responsible for these effects. A. c. conductivity and (N(EF)) the concentration of disordered states exhibited decreasing trend, whereas activation energy for a.c. conduction showed increasing trend with CoO content. Impedance plots drawn as a function of CoO concentration suggested the increasing impedance of the glasses. The quantitative analysis of results of dielectric studies suggested that Co ions prevailingly took part in the glass network in Td locations, facilitated the growing polymerization of the glass structure and thereby increased stiffness of the glass network against the applied electrical filed or increased the electrical insulating strength of the glasses. Finally, it is concluded that these glasses may be considered for applications as transparent electrical shielding sheets in display panels.

Background The routine identification to the species level of Nocardia genus by conventional methods is a fastidious and time-consuming process owing to the limited biochemical reactivity of these microorganisms, often requiring 1 or more days to complete identification. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a new technology for definitive and rapid species identification. Methods We evaluated the MALDI-TOF MS for the identification of 44 clinical isolates of Nocardia species in comparison to 16S ribosomal RNA (rRNA) gene sequencing. Nocardia isolates were identified by microbiological examination, phenotypical tests and MALDI-TOF MS and the results were compared by 16S rRNA gene sequencing. Results Of the 44 Nocardia strains, the identification of 28 isolates was determined with MALDI Biotyper database. According to this, 16 isolates (57.1%) of the strain log scores were ≥2. Two (7.1%) were identified to the species level (log scores of ≥2) as Nocardia otitidiscaviarum. The addition of a newly established Nocardia database (16 new Nocardia strains included to the original database) did significantly improve the scores. The results were 43 (97.7%) correct identification to the species level (log scores of ≥2). Conclusions This study showed that the identification of clinical Nocardia isolates by the Bruker MALDI Biotyper is highly reliable, whereas identification rates are generally lower than those for some Gram-negative bacteria and Gram-positive cocci. Based on our data, the identification rates can be improved by validated new database entries and the results can be confirmed with nucleic acid sequence analysis.

The objective of this work is to explore the Ag ion concentration dependence on structural and dielectric characteristics of Na2O Sb2O3: Ag2O glass ceramics. The prepared glass ceramics were characterized by XRD, XPS, SEM, TEM, EDS and DSC techniques. These studies have revealed that the samples are composed of multiple crystal grains entrenched in the remnant amorphous phase. The IR and Raman spectroscopic studies indicated increasing degree of polymerization of the glass network with increase of Ag2O concentration up to 0.1 mol%. This is attributed to increasing concentration of tetrahedral Sb5+ ions that take part in the glass network forming. Optical absorption spectra have exhibited surface plasmon resonance (SPR) band in the wavelength region 400–450 nm. Quantitative studies on dielectric properties were performed over wide ranges of frequency and temperature and the variations of these properties with the concentration of Ag2O are discussed in the light of various polarization processes. Dipolar orientational effects exhibited by electric moduli spectra suggested multiple relaxation times for electric dipoles. The observed decrease of A.C. conductivity (that contains both ionic and polaronic components) with increase of Ag2O content up to 0.1 mol% is attributed to the increasing degree of polymerization of the glass network that hinders the migration of charge carriers. The polaronic conduction is understood due to exchange of polarons between Sb3+ ‒ Sb5+ and Ag0 Ag+ ions, while ionic conductivity is predicted due to transport of monovalent silver and Na+ ions. A changeover of polaronic to ionic conductivity seemed to take place at about 0.1 mol% Ag2O.

We have determined the entropy, the total energy, and the specific heat of the systems consisting of M ≥ 3 hydrogen molecules. The calculations were conducted in the framework of the nonextensive Tsallis statistics. The relation between M and the entropic index q is given by q = 1 + 1 ∕ M , which results from the fact that the temperature of the nanosystems fluctuates around the temperature of the reservoir (Wilk and Wlodarczyk, 2000). The electron energy states of the hydrogen molecule have been determined with the help of the Hubbard Hamiltonian, which models all two-body interactions. The Hubbard Hamiltonian integrals have been calculated by using the variational method, whereas the Wannier function has been associated with 1 s Slater-type orbitals. We have included the contributions to the energy of the hydrogen molecule coming from the oscillatory (either harmonic or anharmonic), rotational and translational degrees of freedom. In addition, we have investigated the impact of the external force ( F ) or the magnetic field ( h ) on the thermodynamic parameters of the systems. In each case the noticeable deviation from the results of the classical statistical physics can be observed for the systems consisting of M M c ∼ 1 0 3 molecules.

We report on the experimental observation of confinement-induced new phase appearance in acetylsalicylic acid (ASA)–porous glass (PG) composites. In this study, ASA was embedded in PG host matrices of various pore widths (15–200 nm). The Raman spectra and positron annihilation lifetime measurements exhibit the existence of ASA nanocrystals in the PG matrix. The DSC data revealed that the melting temperature TM and excess specific heat decrease with decreasing the size of embedded ASA nanocrystals. The close inspection of the TM dependence versus diameter of filled pores has shown that the ASA crystallizes in polymorph II in confined matrix. Moreover, it was demonstrated that the ASA spatial confinement results in the appearance of new polymorphic phase in the investigated composites—highly likely form ASA III. Both the changes in ASA melting temperatures due to the volume constraints and the decrease in specific heat may be crucial for the bioavailability of the drug.

The objective of this study is to report the results of dielectric properties and dielectric breakdown strength (DBS) of PbO-B2O3-SeO2:Ho2O3 (PBSH) glass ceramics as functions of Au2O3 content and to correlate the results with spectroscopic properties. PBSH glass ceramics with traces of Au2O3 were fabricated and characterized with different techniques that include positron annihilation spectroscopy (PAS). Several dielectric parameters and DBS were studied as functions of Au2O3 concentration. Observed increase of ε′ with Au2O3 content was attributed to a hike in the space charge polarization (scp) due to the increased concentration of structural imperfections. Dipolar relaxation phenomenon exhibited by electric moduli was analyzed using Cole-Cole plots. σ ac (a c, conductivity) showed an increasing tendency with Au2O3 content. Such increase was attributed to the polaronic exchange between two structural groups of SeO2. Inferences drawn from dielectric and DBS studies were found to be in agreement with different spectroscopic properties of these glass ceramics.

The superconducting state in Carbonaceous Sulfur Hydride (C-S-H) system is characterized by the record-high critical temperature of $288$~K experimentally observed at $\sim$267 GPa. Herein, we determined the properties of the \mbox{C-S-H} superconducting phase within the scope of both classical Eliashberg equations (CEE) and the Eliashberg equations with vertex corrections (VCEE). We took into account the scenarios pertinent to either the intermediate or the high value of electron-phonon coupling constant ($\lambda\sim 0.75$ or $\lambda\sim 3.3$, respectively). The scenario for the intermediate value, however, cannot be actually realized due to the anomally high value of logarithmic phonon frequency ($\omega_{\rm ln}/k_{B}=7150$~K) it would require. On the other hand, we found it possible to reproduce correctly the value of $T_{C}$ and other thermodynamic quantities in the case of strong coupling. However, the vertex corrections lower the order parameter values within the range from $\sim 50$~K to $\sim275$~K. For the upper critical field $H_{C2}\sim 27$~T, the Ginzburg-Landau parameter $\kappa$ is of the order of $1.7$. This correlates well with the sharp drop of resistance observed by Hirsch and Marsiglio at the critical temperature. The strong-coupling scenario for C-S-H system is also suggested by the high values of $\lambda$ estimated for ${\rm H_{3}S}$ ($\lambda\sim 2.1$, $\kappa\sim 1.5$), ${\rm LaH_{10}}$ ($\lambda\sim 2.8$-$3.9$, $\kappa\sim 1.6$), and ${\rm YH_{6}}$ ($\lambda\sim 1.7$, $\kappa\sim 1.3$) compounds., Comment: 4 pages

Molecular structure alteration in a polyethylene-polyamine-cured DGEBA-epoxy resin induced by multi-layered graphene nanoplatelets (MLGNPs) have been experimentally studied by broadband dielectric spectroscopy (BDS), thermal-desorption mass-spectroscopy (TDMS), phase-frequency continuous-wave ultrasound probing (USP), compression-mode static mechanical loading (SML), and positron-annihilation lifetime spectroscopy (PALS). The MLGNPs were about 5 × 5 μm in lateral size, about 50 nm in thickness, and of the specific surface area ~790 m2/g. The filler’s loading in the GNP-epoxy nanocomposites varied as 0.5, 1.0, 2.0, and 5.0% by mass. Loading effects in a number of physical parameters sensitive to molecular structure of the nanocomposites have been detected. The physical reasons underlying the effects have been discussed.

This study is devoted to investigate the role of Au0 particles on the improvement of luminescence efficiency of Ho3+ ions in a non-conventional lead boroselenate glass ceramic. Characterization by different spectroscopic techniques indicated that the samples consist of [SeO3]2− and [SeO4]2− structural groups. Among them, the fraction of [SeO3]2− groups exhibited an increasing trend with increase of Au2O3 content. These studies have further revealed that a part of Au3+ ions reduced in to gold nano particles during ceramicization process. Optical absorption (OA) spectra of these samples exhibited a wide absorption band with gradual growth with the Au2O3 concentration. This band is attributed to the surface plasmon resonance (SPR) of gold nanoparticles. Additionally, the OA spectra exhibited several characteristic bands of Ho3+ ions in the spectral region of 450–2000 nm. Photoluminescence (PL) spectra of (Ho free samples) containing gold particles exhibited a broad band in the green to red spectral region, identified due to the transition of electrons from sp → d energy bands of gold nanoparticles. PL spectra of co-doped samples exhibited the emission bands in the green, orange and red regions with enhanced intensities as Au2O3 content is increased. OA and PL spectra were characterized using Judd-Ofelt theory and various radiative parameters were estimated. The impact of Au0 particles on the PL efficiency of holmium ions is comprehensively discussed using kinetic rate equations. The crucial role of gold particles as sensitizers in enhancing the luminescence efficiency especially the green emission is quantitatively explained.

Dielectric properties of heavy metal oxide glass system viz., PbO-Bi2O3-SiO2 mixed with varied concentration of NiO are studied as functions of frequency and temperature. The dielectric parameters viz., e′, tan δ, σa.c. are observed to increase with NiO content. Electric moduli formalism is adopted for the analysis of dipolar relaxation effects. Impedance plots drawn for the glasses doped with different NiO concentrations pointed out decreasing value of electrical impedance of the glass samples with increase of NiO content. Activation energies for dipoles and for a.c. conductivity are found to decrease, whereas the concentration of defect energy states N(EF) is increased with increase of NiO content. Quantitative analysis of these results along with those of spectroscopic studies indicated that with increase of NiO concentration there is gradual growing presence of Ni2+modifier (Oh) ions in the glass matrix. As modifiers these ions are anticipated to stimulate structural defects by depolymerizing the glass network. The increasing degree of disintegration of the glass network is predicted to facilitate for diffusion of conducting ions in the bulk glasses. Finally, it is concluded that in spite of the fact that the host glass is a heavy dense glass (composed of multi component heavy metal oxides with low mobile charge carriers) which has got plenty of other applications in optically operated devices, it is more conducive even for easy diffusion of Ni2+ions that contribute to ionic conductivity. In view of these observations it is concluded that the studied glass may be considered as ionic conducting material to be used in solid electrolytes.

In the framework of strong-coupling formalism, we have calculated the thermodynamic parameters of superconducting state in the ${\rm YB_{6}}$ compound. The values of critical temperature ($T_{C}$) are $9.5$~K and $7.9$~K for the Coulomb pseudopotential $\mu^{\star}=0.1$ and $0.2$, respectively. In the paper, we have determined the low temperature values of order parameter ($\Delta(0)$), specific heat jump at the critical temperature ($\Delta C(T_{C})$), and thermodynamic critical field ($H_C(0)$). The dimensionless thermodynamic ratios: $R_{\Delta}=2\Delta\left(0\right)/{k_BT_C}$, $R_C=\Delta C\left(T_C\right)/C^N\left(T_C\right)$, and $R_H=T_CC^N\left(T_C\right)/H_C^2\left(0\right)$ are equal to: $R_{\Delta}\left(\mu^{\star}\right)\in\lbrace 4.48,4.35\rbrace$, $R_{C}\left(\mu^{\star}\right)\in\lbrace 2.62,2.55\rbrace$, and $R_{H}\left(\mu^{\star}\right)\in\lbrace 0.146,0.157\rbrace$. Due to the significant strong-coupling and retardation effects ($k_{B}T_{C} / \omega_{\rm ln}\sim 0.1$) those values highly deviate from the predictions of BCS theory., Comment: 5 pages, 4 figures

Abnormality of dopamine D2 receptor (D2R) function, often observed as D2R supersensitivity (D2RSS), is a commonality of schizophrenia and related psychiatric disorders in humans. Moreover, virtually all psychotherapeutic agents for schizophrenia target D2R in brain. Permanent D2RSS as a feature of a new animal model of schizophrenia was first reported in 1991, and then behaviorally and biochemically characterized over the next 15–20 years. In this model of schizophrenia characterized by production of D2RSS in ontogeny, there are demonstrated alterations of signaling processes, as well as functional links between the biologic template of the animal model and ability of pharmacotherapeutics to modulate or reverse biologic and behavioral modalities toward normality. Another such animal model, featuring knockout of trace amine-associated receptor 1 (TAAR1), demonstrates D2RSS with an increase in the proportion of D2R in the high-affinity state. Currently, TAAR1 agonists are being explored as a therapeutic option for schizophrenia. There is likewise an overlay of D2RSS with substance use disorder. The aspect of adenosine A2A-D2 heteroreceptor complexes in substance use disorder is highlighted, and the association of adenosine A2A receptor antagonists in discriminative and rewarding effects of psychostimulants is outlined. In summary, these new animal models of schizophrenia have face, construct, and predictive validity, and distinct advantages over earlier models. While the review summarizes elements of D2RSS in schizophrenia per se, and its interplay with substance use disorder, a major focus is on presumed new molecular targets attending D2RSS in schizophrenia and related clinical entities.

Origin of atomic-deficient free-volume structure in ZnO–ZrO2–B2O3 glass ceramic versus ZrO2 concentration was explored by positron annihilation lifetime spectroscopy (PAL) technique. XRD and SEM studies, on the titled samples indicated that the samples consist of tetragonal ZnZrO3 perovskite crystal phases. The IR spectroscopic studies suggested that Zr4+ ions prevailingly occupy octahedral positrons and play crucial role in formation of positron trapping holes in the samples. The PAL studies using 0.1 MBq 22Na positron source indicated a significant variation in the positron annihilation life time with increasing ZrO2 for both positron- and positronium (Ps) trapping channels. The intensity of the longest positron annihilation component I3 is decreased from 4.45 to 3.07%, whereas o-Ps decay lifetime τ3 is enhanced from 1.18 to 1.34 ns with increase of ZrO2 from 0 to 5.0 mol%. These results suggested that the glass ceramic CZ5 contains the maximum free space or void expansion and void agglomeration.

The objective of this study is to investigate the influence of silver ions on a.c. conductivity and dielectric properties of lead arsenate glass ceramics. PbO–As2O3 glasses mixed with different concentrations of Ag2O were prepared by conventional melt quenching technique and later were ceramicized by heat treatment at crystallization temperature for about 72 h. The prepared samples were characterized by XRD, SEM and DSC techniques. The SEM studies have indicated the samples are embedded with different crystal phases of varying sizes from 0.2 to 1.0 µm and the fraction of crystal phases as well as the size of the crystallites increased with increase of Ag2O concentration. The X–ray diffraction studies have revealed that the samples composed of different crystal phases viz., Ag3AsO4, AgPb4(AsO4)3, Pb2As2O5 and PbAs2O4 entrenched in the residual amorphous phase. The spectroscopic studies viz., optical absorption and IR spectroscopic studies have revealed a gradual increase in the degree of depolymerization of the glass network with increase in the concentration of Ag2O. Photoluminescence studies have indicated that the investigated glass ceramics contain silver ion clusters; the concentration of such clusters is predicted to be higher in the samples containing higher content of Ag2O. Finally, we have carried out extensive studies on dielectric properties viz., dielectric constant, loss, electric moduli, impedance spectra and a.c. conductivity over broad ranges of continuous frequencies (3–100 kHz) and temperatures (298–600 K). The obtained results were quantitatively analyzed in terms of different polarization mechanisms. The relaxation effects exhibited by the electric moduli were analyzed in a detailed way by different methods. Spreading of relaxation times for dipoles was established and the possible dipoles responsible for such relaxation effects were suggested. The observed increase of a.c. conductivity with the concentration of Ag2O is attributed to the contribution of both polaronic and ionic transport. Finally, it is concluded that the samples crystallized with higher content of Ag2O exhibit predominantly ionic conductivity and hence such glass ceramics may be useful as solid electrolytes for solid state batteries.

This study is mainly focused on dielectric properties of lead arsenate glasses crystallized with different concentrations of CuO over continuous ranges of frequency (3 Hz −100 kHz) and temperature (300–633 K). The glasses were prepared by melt quenching technique and were heat treated for prolonged time for ceramization. Prepared samples were characterized by XRD, SEM and DSC techniques. SEM studies indicated that the samples are composed of small crystal grains of the size varying from 0.2 to 1.0 µm cemented with the residual glass phase. XRD studies indicated CuAs2O4, Pb2Cu7(AsO4)6 and Cu2O are the main crystal phases developed during the crystallization. Optical absorption studies confirmed the presence of copper ions in Cu+ valence state in addition to Cu2+ state and the fraction of Cu+ ions is found to increase with the content of CuO. The optical band gap exhibited increasing trend with CuO content. IR spectral studies indicated an increase of degree of polymerization of the glass network with the CuO content. The observed variations of dielectric parameters with frequency, temperature and CuO content are discussed using different polarization mechanisms. The dielectric relaxation effects exhibited by the loss tangent and the electric moduli are analyzed using graphical method and observed relaxation effects are attributed to the complexes of divalent copper ions with oxygens. The impedance diagrams indicated increase of bulk resistance of the samples with increase of CuO content. The ac conductivity exhibited a decreasing trend with increase of CuO content. The conduction phenomenon is explained using polaron hopping between Cu+ and Cu2+ ions. The temperature independent part of the conductivity is explained using quantum mechanical tunneling (QMT) model. Finally, it is concluded that the insulating strength of the material increased with CuO content and such materials may be useful as electrical insulators in the low temperature region

Impact of nanosized oxide particles of titania (titanium dioxide, rutile) and silica–titania fumed compound on structure relaxation processes in nanocomposites of an orthophtalic unsaturated styrene cross-linked polyester resin has been experimentally studied using the thermal desorption mass spectroscopy, the dielectric spectroscopy, and the positron annihilation lifetime spectroscopy. All the nanocomposites showed unmonotonous variations in the thermal resistance, the dielectric permittivity and losses, and the annihilation rates for both positrons and ortho-positronium atoms with increasing filler’s loading. The nanoparticle-loading effects can be explained on the assumption that the oxide particles embedded into a cross-linked polyester resin induce rearrangements in its structure. Several mechanisms of particle–polymer interface interaction compete simultaneously and thus promote the alterations in molecular structure of the nanocomposites. The mechanisms may include both chemical and electrostatic fastening of polyester chains and styrene cross-links to the active surface sites, the destruction of the styrene cross-links, and redistribution of electron density in polymers. The features of the loading effects observed in the different nanocomposites can be ascribed to distinctions in both of active surface sites and intrinsic dielectric properties of the filling oxide particles.

Zinc borate glasses with different concentrations of Nb2O5 were prepared and later were heat treated for prolonged times. Prepared samples were characterized by XRD, SEM and DSC and IR and optical transmission spectroscopy techniques. Later, dielectric properties viz., dielectric constant, loss tangent, electric modulii, electrical impedance and a.c. conductivity over wide ranges of frequency and temperature, have been investigated as a function of Nb2O5 concentration. Finally, the dielectric breakdown strength was measured in air medium at ambient temperature. The results of characterization techniques viz., XRD, SEM and DSC indicated that multiple crystal grains (with sizes varying from 0.1 to 1 μm) are dispersed in the residual glass phase. The concentration of crystal grains is found to increase with increase of Nb2O5 content. The XRD studies have further revealed that the bulk samples are composed of columbite ZnNb2O6 crystal phases. Using generalized gradient approximation (GGA) quantitative information on these crystal phases viz., the lattice parameters, optical band gap and band structure were evaluated. The analysis of results of IR spectral studies have indicated that there is an increasing degree of polymerization of glass network with increase of Nb2O5 content due to the increased connectivity between various structural groups in the glass network. The optical absorption spectra indicated an increase of optical transmittance of the bulk samples with increase of Nb2O5 content. The dielectric parameters are observed to decrease, whereas the dielectric breakdown strength is observed to increase to a large extent due to the crystallization of the glass with the Nb2O5. The increase is attributed to the formation of ZnNb2O6 crystalline phases that contain intertwined ZnO6 and NbO6 structural units. As a whole, zinc borate glasses exhibited a significant increase in the electrical insulating strength due to the crystallization with Nb2O5 as the crystallizing agent. Further, the value of dielectric constant is also found to be the optimal with no dispersion with frequency upto 450 K. Overall, the studied glass ceramics meet the necessary physical conditions to be used as insulating layers in the display panels and hence may be considered for such applications. This article is protected by copyright. All rights reserved.

Serotoninergic nerves are known to modulate sensitization of dopamine receptors (DA-R) in a rodent model of Parkinson’s disease (PD). However, serotoninergic nerves are not known to have a prominent role on DA exocytosis in intact rats. The current study was undertaken to explore the possible influence of serotoninergic nerves on DA exocytosis in Parkinsonian rats. Rat pups were treated at 3 days after birth with the neurotoxin 6-hydroxydopamine (6-OHDA; 134 μg icv, half into each lateral ventricle; desipramine, 1 h pretreatment), in order to produce marked long-lasting destruction of neostriatal dopaminergic innervation, as evidenced by the 90–95% depletion of DA (p