Dramatic improvement of NO reduction activity via reversible re-dispersion of CeO2 nanoparticles into Ce+3 atoms on alumina under high temperature reactive treatment

Ceria nanoparticles supported on gamma-alumina prepared via wet impregnation and sourced commercially have low activity for industrially relevant NO reduction by CO in the presence of steam. These supports contain ceria nanoparticles as well as small (~1%) amount of Ce atomically dispersed and anchored by penta-Al sites. We discovered that treatment of these catalysts at temperatures ~750-950 ºC under the flow of CO and NO in the presence of steam, which typically leads to catalyst deterioration and sintering, in fact, leads to dispersion of ceria nanoparticles into isolated Ce+3 atoms. We extensively characterize them with XPS, FTIR and HAADF-STEM imaging. Their presence changes the alumina surface, as evidenced by XPS and FTIR with probe molecules. Ce+3 ions show dramatically enhanced NO reduction ability in the presence of CO and steam. Infra-red studies reveal close interaction of NO molecules on Ce+3/Alumina surfaces with the formation of N2O species. Heating these samples in oxygen (in wet or dry streams) at 800 ºC and above leads to coalescence of Ce+3 into CeO2 nanoparticles, resulting in reversible loss of activity. Further, reactive treatment of CeO2/Al2O3 under high temperature reaction conditions restores Ce+3 cations as well as catalytic activity. Our study shows reversible redispersion of ceria into isolated Ce+3 cations under conditions where typical catalyst sintering is generally assumed to occur and suggests a pathway to utilize these materials as supports for more effective catalysis. Indeed, supporting only 0.1-0.5 wt% Rh on these CeAl supports, shows synergies between Rh and atomically dispersed Ce ions with excellent activity and stability for NO reduction with CO.

Anesthetics fragment hippocampal network activity, alter spine dynamics, and affect memory consolidation

General anesthesia is characterized by reversible loss of consciousness accompanied by transient amnesia. Yet, long-term memory impairment is an undesirable side effect. How different types of general anesthetics (GAs) affect the hippocampus, a brain region central to memory formation and consolidation, is poorly understood. Using extracellular recordings, chronic 2-photon imaging, and behavioral analysis, we monitor the effects of isoflurane (Iso), medetomidine/midazolam/fentanyl (MMF), and ketamine/xylazine (Keta/Xyl) on network activity and structural spine dynamics in the hippocampal CA1 area of adult mice. GAs robustly reduced spiking activity, decorrelated cellular ensembles, albeit with distinct activity signatures, and altered spine dynamics. CA1 network activity under all 3 anesthetics was different to natural sleep. Iso anesthesia most closely resembled unperturbed activity during wakefulness and sleep, and network alterations recovered more readily than with Keta/Xyl and MMF. Correspondingly, memory consolidation was impaired after exposure to Keta/Xyl and MMF, but not Iso. Thus, different anesthetics distinctly alter hippocampal network dynamics, synaptic connectivity, and memory consolidation, with implications for GA strategy appraisal in animal research and clinical settings.

Water Influence on the Uniaxial Tensile Behavior of Polytetrafluoroethylene-Coated Glass Fiber Fabric

Polytetrafluoroethylene (PTFE)-coated glass fiber fabrics are used for long-lasting membrane structures due to their outstanding mechanical properties, chemical stabilities, and satisfying service life. During their operation time, different environmental impacts might influence their performance, especially regarding the mechanical properties. In this contribution, the impact of water on the tensile strength deterioration was assessed experimentally, providing evidence of considerable but partially reversible loss of strength by up to 20% among the various types of investigated industrially established fabrics.

All-or-none disconnection of pyramidal inputs onto parvalbumin-positive interneurons gates ocular dominance plasticity

ABSTRACTDisinhibition is an obligatory initial step in the remodeling of cortical circuits by sensory experience, yet the underlying mechanisms remain unclear. Our investigation of mechanisms for disinhibition in the classical model of ocular dominance plasticity (ODP) uncovered an unexpected novel form of experience-dependent circuit plasticity. In layer 2/3 of mouse visual cortex monocular deprivation triggers an “all-or-none” elimination of approximately half the connections from local pyramidal cells onto parvalbumin-positive interneurons (Pyr→PV), without affecting the strength of the remaining connections. This loss of Pyr→PV connections is transient, lasting one day only, has a critical period commensurate with the ODP critical period, and is contingent on a reduction of neuropentraxin2 (NPTX2), which normally stabilizes Pyr→PV connections. Bidirectional manipulations of NPTX2 functionality that prevent/promote the elimination Pyr→PV connections also promote/prevent ODP. We surmise, therefore, that this rapid and reversible loss of local Pyr→PV circuitry gates experience-dependent cortical plasticity.

A comparative evaluation of efficacy of epidural dexmedetomidine and fentanyl as adjunct to 0.2% ropivacaine for post-operative analgesia in elective abdominal surgeries

<p class="abstract"><strong>Background:</strong> Epidural analgesia as a central nuraxial technique which involves use of local anesthetics injected into the epidural space to produce a reversible loss of sensation and is the one of the most common regional technique used for lover abdominal and lover limb surgeries epidural analgesia provides excellent pain relief for surgical procedures below the umbilicus. This study compared the efficacy of epidural dexmedetomidine and fentanyl in addition to 0.2% ropivacaine for post-operative analgesia in elective abdominal surgeries.</p><p class="abstract"><strong>Methods:</strong> Total of 150 patients American Society of Anesthesiologists (ASA) I and II between 20-60 years, undergoing major abdominal surgery were included in this study. The patients divided in three groups of 50 patients each. First group R (ropivaciain 0.2% 9 ml with 1ml normal saline) second group RF (ropivacain 0.2% 9 ml with fentanyl 1 ml) and third group RD (ropivaciain 0.2% 9 ml with dexmedetomidine 1 μ/kg).</p><p class="abstract"><strong>Results:</strong> There is no significant difference in age, weight, sex, and ASA grade in all three groups.</p><p class="abstract">Hypotension was observed in 4 (8%) patients of R group, 2 (4%) in RD group and 4 (8%) in RF group. The shivering was present in 2 (4%) R group and 2 (4%) in RD group. Nausea, vomiting was present in R group 2 (4%) and 2 (4%) in RF group. There was no significant difference between the three groups with respect to hemodynamic parameters like heart rate, systolic and diastolic blood pressure and respiratory rate.</p><p class="abstract"><strong>Conclusions: </strong>Dexmedetomidine is a better adjuvant to ropivacaine through epidural route when compared to fentanyl for providing early onset prolonged post-operative analgesia, sedation and stable hemodynamic parameters in intra-abdominal surgeries.</p>

Frustrated Flexibility in Metal-Organic Frameworks

<div><div><div><p>Stimuli-responsive flexible metal-organic frameworks (MOFs) remain at the forefront of porous materials research due to their enormous potential for various technological applications. Here, we introduce the concept of frustrated flexibility in MOFs, which arises from an incompatibility of intra-framework dispersion forces with the geometrical constraints of the inorganic building units. Controlled by appropriate linker functionalization with dispersion energy donating alkoxy groups, this approach results in a series of MOFs exhibiting a new type of guest- and temperature-responsive structural flexibility characterized by reversible loss and recovery of crystalline order under full retention of framework connectivity and topology. The stimuli-dependent phase change of the frustrated MOFs involves non-correlated deformations of their inorganic building unit, as probed by a combination of global and local structure techniques together with computer simulations. Frustrated flexibility may be a common phenomenon in MOF structures, which are commonly regarded as rigid, and thus may be of crucial importance for the performance of these materials in various applications.</p></div></div></div>

Frustrated Flexibility in Metal-Organic Frameworks

<div><div><div><p>Stimuli-responsive flexible metal-organic frameworks (MOFs) remain at the forefront of porous materials research due to their enormous potential for various technological applications. Here, we introduce the concept of frustrated flexibility in MOFs, which arises from an incompatibility of intra-framework dispersion forces with the geometrical constraints of the inorganic building units. Controlled by appropriate linker functionalization with dispersion energy donating alkoxy groups, this approach results in a series of MOFs exhibiting a new type of guest- and temperature-responsive structural flexibility characterized by reversible loss and recovery of crystalline order under full retention of framework connectivity and topology. The stimuli-dependent phase change of the frustrated MOFs involves non-correlated deformations of their inorganic building unit, as probed by a combination of global and local structure techniques together with computer simulations. Frustrated flexibility may be a common phenomenon in MOF structures, which are commonly regarded as rigid, and thus may be of crucial importance for the performance of these materials in various applications.</p></div></div></div>

Anesthetics uniquely decorrelate hippocampal network activity, alter spine dynamics and affect memory consolidation

SUMMARYGeneral anesthesia is characterized by reversible loss of consciousness accompanied by transient amnesia. Yet, long-term memory impairment is an undesirable side-effect. How different types of general anesthetics (GAs) affect the hippocampus, a brain region central to memory formation and consolidation, is poorly understood. Using extracellular recordings, chronic 2-photon imaging and behavioral analysis, we monitor the effects of isoflurane (Iso), medetomidine/midazolam/fentanyl (MMF), and ketamine/xylazine (Keta/Xyl) on network activity and structural spine dynamics in the hippocampal CA1 area of adult mice. GAs robustly reduced spiking activity, decorrelated cellular ensembles, albeit with distinct activity signatures, and altered spine dynamics. Iso anesthesia most closely resembled wakefulness, and network alterations recovered more readily than with Keta/Xyl and MMF. Correspondingly, memory consolidation was impaired after exposure to Keta/Xyl and MMF, but not Iso. Thus, different anesthetics distinctly alter hippocampal network dynamics, synaptic connectivity, and memory consolidation, with implications for GA strategy appraisal in animal research and clinical settings.