Cas9 deactivation with photocleavable guide RNAs.

Precise control of CRISPR-Cas9 would improve its safety and applicability. Controlled CRISPR inhibition is a promising approach but is complicated by separate inhibitor delivery, incomplete deactivation, and slow kinetics. To overcome these obstacles, we engineered photocleavable guide RNAs (pcRNAs) that endow Cas9 nucleases and base editors with a built-in mechanism for light-based deactivation. pcRNA enabled the fastest (<1 min) and most complete (<1% residual indels) approach for Cas9 deactivation. It also exhibited significantly enhanced specificity with wild-type Cas9. Time-resolved deactivation revealed that 12-36 h of Cas9 activity or 2-4 h of base editor activity was sufficient to achieve high editing efficiency. pcRNA is useful for studies of the cellular response to DNA damage by abolishing sustained cycles of damage and repair that would otherwise desynchronize response trajectories. Together, pcRNA expands the CRISPR toolbox for precision genome editing and studies of DNA damage and repair.

Distinctive and Complementary Roles of Default Mode Network Subsystems in Semantic Cognition.

The default mode network (DMN) typically deactivates to external tasks, yet supports semantic cognition. It comprises medial temporal (MT), core, and frontotemporal (FT) subsystems, but its functional organization is unclear: the requirement for perceptual coupling versus decoupling, input modality (visual/verbal), type of information (social/spatial), and control demands all potentially affect its recruitment. We examined the effect of these factors on activation and deactivation of DMN subsystems during semantic cognition, across four task-based human functional magnetic resonance imaging (fMRI) datasets, and localized these responses in whole-brain state space defined by gradients of intrinsic connectivity. FT showed activation consistent with a central role across domains, tasks, and modalities, although it was most responsive to abstract, verbal tasks; this subsystem uniquely showed more "tuned" states characterized by increases in both activation and deactivation when semantic retrieval demands were higher. MT also activated to both perceptually coupled (scenes) and decoupled (autobiographical memory) tasks and showed stronger responses to picture associations, consistent with a role in scene construction. Core DMN consistently showed deactivation, especially to externally oriented tasks. These diverse contributions of DMN subsystems to semantic cognition were related to their location on intrinsic connectivity gradients: activation was closer to the sensory-motor cortex than deactivation, particularly for FT and MT, while activation for core DMN was distant from both visual cortex and cognitive control. These results reveal distinctive yet complementary DMN responses: MT and FT support different memory-based representations that are accessed externally and internally, while deactivation in core DMN is associated with demanding, external semantic tasks.

Structure-function analysis of plant G-protein regulatory mechanisms identifies key Gα-RGS protein interactions.

Heterotrimeric GTP-binding protein alpha subunit (Gα) and its cognate regulator of G-protein signaling (RGS) protein transduce signals in eukaryotes spanning protists, amoeba, animals, fungi, and plants. The core catalytic mechanisms of the GTPase activity of Gα and the interaction interface with RGS for the acceleration of GTP hydrolysis seem to be conserved across these groups; however, the RGS gene is under low selective pressure in plants, resulting in its frequent loss. Our current understanding of the structural basis of Gα:RGS regulation in plants has been shaped by Arabidopsis Gα, (AtGPA1), which has a cognate RGS protein. To gain a comprehensive understanding of this regulation beyond Arabidopsis, we obtained the x-ray crystal structures of Oryza sativa Gα, which has no RGS, and Selaginella moellendorffi (a lycophyte) Gα that has low sequence similarity with AtGPA1 but has an RGS. We show that the three-dimensional structure, protein-protein interaction with RGS, and the dynamic features of these Gα are similar to AtGPA1 and metazoan Gα. Molecular dynamic simulation of the Gα-RGS interaction identifies the contacts established by specific residues of the switch regions of GTP-bound Gα, crucial for this interaction, but finds no significant difference due to specific amino acid substitutions. Together, our data provide valuable insights into the regulatory mechanisms of plant G-proteins but do not support the hypothesis of adaptive co-evolution of Gα:RGS proteins in plants.

Boosting the Downconversion Luminescence of Tm3+-Doped Nanoparticles for S-Band Polymer Waveguide Amplifier.

Polymer waveguide devices have attracted increasing interest in several rapidly developing areas of broadband communications since they are easily adaptable to on-chip integration and promise low propagation losses. As a key member of the waveguide gain medium, lanthanide doped nanoparticles have been intensively studied to improve the downconversion luminescence. However, current research efforts are almost confined to erbium-doped nanoparticles and amplifiers operating at the C-band; boosting the downconversion luminescence of Tm3+ for S-band optical amplification still remains a challenge. Here we report a Tb3+-induced deactivation control to enhance Tm3+ downconversion luminescence in a stoichiometric Yb lattice without suffering from concentration quenching. We also demonstrate their potential application in an S-band waveguide amplifier and record a maximum optical gain of 18 dB at 1464 nm. Our findings provide valuable insights into the fundamental understanding of deactivation-controlled luminescence enhancement and open up a new avenue toward the development of an S-band polymer waveguide amplifier with high gain.

On the antibacterial photodynamic inactivation mechanism of Emodin and Dermocybin natural photosensitizers: A theoretical investigation.

A DFT and TDDFT study has been carried out on monomeric anthraquinones Emodin and Dermocybin (Em, Derm) recently proposed as natural antibacterial photosensitizers able to act also against gram-negative microbes. The computational study has been performed considering the relative amount of neutral and ionic forms of each compound in water, with the variation of pH. The occurrence of both Type I and Type II photoreactions has been explored computing the absorption properties of each species, the spin-orbit coupling constants (SOC), the vertical ionization potentials and the vertical electron affinities. The most plausible deactivation channels leading to the population of excited triplet states have been proposed. Our data indicate Emodin as more active than Dermocybin in antimicrobial photodynamic therapy throughout the Type II mechanism. Our data support a dual TypeI/II activity of the monomeric anthraquinones Emodin and Dermccybin in water, in all the considered protonation states.

Plenty of Space in the Backbone: Radical Ring-Opening Polymerization.

Radical polymerization is the most widely applied technique in both industry and fundamental science. However, its major drawback is that it typically yields polymers with non-functional, non-degradable all-carbon backbones-a limitation that radical ring-opening polymerization (rROP) allows to overcome. The last decade has seen a surge in rROP, primarily focused on creating degradable polymers. This pursuit has resulted in the creation of the first readily degradable materials through radical polymerization. Recent years have witnessed innovations in new monomers that address previous design limitations, such as ring strain and reactivity ratios. Furthermore, advances in integrating rROP with reversible deactivation radical polymerization (RDRP) have facilitated the incorporation of complex, customizable chemical payloads into the main polymer chain. This short review discusses the latest developments in monomer design with a focused analysis of their limitations in a broader historical context. Recently evolving strategies for compatibility of rROP monomers with RDRP are discussed, which are key to precision polymer synthesis. The latest chemistry surveyed expands the horizon beyond mere hydrolytic degradation. Now is the time to explore the chemical potential residing in the previously inaccessible polymer backbone.

An experimental and modeling approach to describe the deactivation of cellulases at the air-liquid interface.

Understanding the reaction mechanisms involved in the enzymatic hydrolysis of cellulose is important because it is kinetically the most limiting step of the bioethanol production process. The present work focuses on the enzymatic deactivation at the air-liquid interface, which is one of the aspects contributing to this global deactivation. This phenomenon has already been experimentally proven, but this is the first time that a model has been proposed to describe it. Experiments were performed by incubating Celluclast cocktail solutions on an orbital stirring system at different enzyme concentrations and different surface-to-volume ratios. A 5-day follow-up was carried out by measuring the global FPase activity of cellulases for each condition tested. The activity loss was proven to depend on both the air-liquid surface area and the enzyme concentration. Both observations suggest that the loss of activity takes place at the air-liquid surface, the total amount of enzymes varying with volume or enzyme concentration. Furthermore, tests performed using five individual enzymes purified from a Trichoderma reesei cocktail showed that the only cellulase that is deactivated at the air-liquid interface is cellobiohydrolase II. From the experimental data collected by varying the initial enzyme concentration and the ratio surface to volume, it was possible to develop, for the first time, a model that describes the loss of activity at the air-liquid interface for this configuration.

Photo-Deactivation Strategy for Switchable ATRP with the Assistance of Molecular Switches.

Light irradiation is an external stimulus, rapidly developed in switchable atom transfer radical polymerization (ATRP) via photo-activation methods in recent years. Herein, a photo-deactivation strategy is introduced to regulate ATRP with the assistance of photoswitchable hexaarylbiimidozole (HABI). Under visible light irradiation and in the presence of HABI, ATRP is greatly decelerated or quenched depending on the concentration of HABI. Interestingly, with visible light off, ATRP can proceed smoothly and follow a first-order kinetics. Moreover, photo-switchable ATRP alternatively with light off and on is demonstrated. Besides, the mechanism of photo-deactivation ATRP involving radical quenching is proposed in the presence of HABI.

A distinct intra-individual suppression subnetwork in the brain's default mode network across cognitive tasks.

Suppression of the brain's default mode network (DMN) during external goal-directed cognitive tasks has been consistently observed in neuroimaging studies. However, emerging insights suggest the DMN is not a monolithic "task-negative" network but is comprised of subsystems that show functional heterogeneity. Despite considerable research interest, no study has investigated the consistency of DMN activity suppression across multiple cognitive tasks within the same individuals. In this study, 85 healthy 15- to 25-year-olds completed three functional magnetic resonance imaging tasks that were designed to reliably map DMN suppression from a resting baseline. Our findings revealed a distinct suppression subnetwork across the three tasks that comprised traditional DMN and adjacent regions. Specifically, common suppression was observed in the medial prefrontal cortex, the dorsal-to-mid posterior cingulate cortex extending to the precuneus, and the posterior insular cortex and parietal operculum. Further, we found the magnitude of suppression of these regions were significantly correlated within participants across tasks. Overall, our findings indicate that externally oriented cognitive tasks elicit common suppression of a distinct subnetwork of the broader DMN. The consistency to which the DMN is suppressed within individuals suggests a domain-general mechanism that may reflect a stable feature of cognitive function that optimizes external goal-directed behavior.

Reforming of biomass-derived producer gas using toluene as model tar: Deactivation and regeneration studies in Ni and K-Ni catalysts.

Within the syngas production from biomass gasification, tar removal constitutes a chief issue to overcome for advanced catalytic systems. This work investigates the performance of Ni and Ni-K catalysts for reforming of derived-biomass producer gas using toluene as model tar. At 750 °C and 60Lg-1h-1, the stability test (70 h) revealed stable performances (CO2, CH4 and C7H8 conversions of 60, 95 and 100%, correspondingly) uniquely for the Ni-K catalyst. Although the efficient protection towards coking let by K was demonstrated, TPO studies over the post-reacted systems still evidenced the presence of carbon deposits for both samples. Conducting three successive reaction/regeneration cycles with different gasifying agents (air, steam and CO2) at 800 °C for 1h, the capability towards regeneration of both catalytic systems was assessed and the spent catalysts were characterized by XRD, SEM and TEM. While none of the regeneration treatments recovered the performance of the unpromoted catalyst, the Ni-K catalysts demonstrated the capability of being fully regenerated by air and CO2 and exhibited analogous catalytic performances after a series of reaction/regeneration cycles. Hence, it is proved that the addition of K into Ni catalysts not only enhances the resistance against deactivation but enables rather facile regenerative procedures under certain atmospheres (air and CO2).

Recycling thermally deactivated asbestos cement in mortar: A possible route towards a rapid conclusion of the "asbestos problem".

The "asbestos problem" arises from the fact that asbestos is still abundant in many buildings and represents a hazard for human health. Current strategies adopted by law aiming at mitigating this hazard are far from being ideal. A smarter solution would be an energy sustainable detoxification treatment followed by recycling. If adopted, it would preserve the environment from pollution, natural resources from depletion and human health from hazard. Asbestos-cement slates were thermally deactivated through a sustainable process and reused in mortar for plaster applications. We found that the addition up to 7 wt% of the deactivated product does not affect significantly the water demand; does not affect thixotropy, stickiness and spreadability of the plastic mixture; slightly increases the strength of the mortar; does not compromise mechanical properties after aging. Considering the huge amount of traditional mortar employed worldwide, a rapid end of the "asbestos problem" is envisaged.

Assessing the Effects of Thiazole-Carboxamide Derivatives on the Biophysical Properties of AMPA Receptor Complexes as a Potential Neuroprotective Agent.

An optimal balance between excitatory and inhibitory transmission in the central nervous system provides essential neurotransmission for good functioning of the neurons. In the neurology field, a disturbed balance can lead to neurological diseases like epilepsy, Alzheimer's, and Autism. One of the critical agents mediating excitatory neurotransmission is α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors, which are concerned with synaptic plasticity, memory, and learning. An imbalance in neurotransmission finally results in excitotoxicity and neurological pathologies that should be corrected through specific compounds. Hence, the current study will prove to be an evaluation of new thiazole-carboxamide derivatives concerning AMPAR-modulating activity and extended medicinal potential. In the current project, five previously synthesized thiazole-carboxamide derivatives, i.e., TC-1 to TC-5, were used to interact with the AMPARs expressed in HEK293T cells, which overexpress different subunits of the AMPAR. Patch-clamp analysis was carried out while the effect of the drugs on AMPAR-mediated currents was followed with a particular emphasis on the kinetics of inhibition, desensitization, and deactivation. All tested TC compounds, at all subunits, showed potent inhibition of AMPAR-mediated currents, with TC-2 being the most powerful for all subunits. These compounds shifted the receptor kinetics efficiently, mainly enhancing the deactivation rates, and hence acted as a surrogate for their neuroprotective potentials. Additionally, recently published structure-activity relationship studies identified particular substituent groups as necessary for improving the pharmacologic profiles of these compounds. In this regard, thiazole-carboxamide derivatives, particularly those classified as TC-2, have become essential negative allosteric modulators of AMPAR function and potential therapeutics in neurological disturbances underlain by the dysregulation of excitatory neurotransmission. Given their therapeutic effectiveness and safety profiles, these in vivo studies need to be further validated, although computational modeling can be further developed for drug design and selectivity. This will open possibilities for new drug-like AMPAR negative allosteric modulators with applications at the clinical level toward neurology.

Density Functional Calculation and Evaluation of the Spectroscopic Properties and Luminescent Material Application Potential of the N-Heterocyclic Platinum(II) Tetracarbene Complexes.

A series of reported Pt(II) carbene complexes possibly have the ability to serve as the new generation of blue emitters in luminescent devices because of their narrow emission spectra, high photoluminescence quantum yields (PLQYs), and rigid molecular skeleton. However, the combination of all carbene ligands with different multidentate structures will affect the overall planarity and horizontal dipole ratio to varying degrees, but the specific extent of this effect has not previously been analyzed in detail. In this work, density functional computation is used to study a class of platinum tetracarbene bidentate complexes with similar absorption and emission band characteristics, which is the main reason for the remarkable difference in quantum efficiency due to subtle differences in electronic states caused by different ligands. From the calculation results, the major reason, which results in significantly decrease in quantum efficiency for [Pt(cyim)2]2+, is that [Pt(cyim)2]2+ can reach the non-radiative deactivation metal-centered d-d excited state through an easier pathway compared with [Pt(meim)2]2+. The result, based on changes in the dihedral angle between ligands, can achieve the goal of improving and designing materials by adjusting the degree of the dihedral angle. (meim: bis(1,1'-dimethyl-3,3'-methylene-diimidazoline-2,2'-diylidene); cyim: bis(1,1'-dicyclohexyl-3,3'-methylene-diimidazoline-2,2'-diylidene).

Exploring Deactivation Reasons of Biomass-Based Phosphorus-Doped Carbon as a Metal-Free Catalyst in the Catalytic Dehydroaromatization of n-Heptane.

Catalytic dehydroaromatization of n-alkanes into high-value aromatics has garnered extensive interest from both academia and industry. Our group has previously reported that phosphorus-doped carbon materials exhibit high selectivity for C-H bond activation in the dehydroaromatization of n-hexane. In this study, using n-heptane as a probe, we synthesized biomass-based phosphorus-doped carbon catalysts to investigate the impact of hydrogen heat treatment and carbon deposition on catalyst structure. Despite achieving an initial conversion of n-heptane at approximately 99.6%, with a toluene selectivity of 87.9%, the catalyst activity fell quickly. Moreover, longer hydrogen treatment time and higher hydrogen concentrations were found to accelerate catalyst deactivation. Thermogravimetric analysis (TGA) and N2 adsorption measurements (BET) indicated that a small amount of coke deposition was not the primary cause of catalyst deactivation. Temperature-programmed desorption of ammonia gas (NH3-TPD) revealed a significant decrease in acid-active functional groups. X-ray photoelectron spectroscopy (XPS) and solid-state 31P NMR spectroscopy confirmed the reduction of active central phosphorus species. These results suggest that catalyst deactivation primarily arises from the decrease in acidity and the partial reduction of phosphorus-containing groups, leading to a substantial loss of active sites. This work contributes new perspectives to understanding the properties and design improvements of metal-free carbon catalysts.

"But I Have a Pacer There Is No Point in Engaging in Hypothetical Scenarios": A Non-Imminently Dying Patient's Request for Pacemaker Deactivation.

In this case report, we describe a woman with advancing dementia who still retained decisional capacity and was able to clearly articulate her request for deactivation of her implanted cardiac pacemaker-a scenario that would result in her death. In this case, the patient had the autonomy to make her decision, but clinicians at an outside hospital refused to deactivate her pacemaker even though they were in unanimous agreement that the patient had capacity to make this decision, citing personal discomfort and a belief that her decision seemed out of proportion to her suffering. We evaluated her at our hospital, found her to have decision-making capacity, and deactivated her pacer resulting in her death about 9 days later. While some clinicians may be comfortable discussing patient preferences for device deactivation in patients who are imminently dying, we can find no reports in the literature of requests for device deactivation from patients with terminal diagnoses who are not imminently dying.

[Does aspirin therapy after desensitization still have a role in treatment of chronic rhinosinusitis with nasal polyposis in the era of biologics?] / Hat die ASS-Desaktivierung in Zeiten von Biologika noch einen Stellenwert bei chronischer Rhinosinusitis mit nasaler Polyposis?

The prevalence of analgesic intolerance syndrome (AIS), internationally known as NSAID-exacerbated respiratory disease (NERD), is reported to be 0.5-5.7% in the general population. The disease often begins with nasal symptoms, which are later joined by chronic rhinosinusitis with nasal polyposis (CRSwNP), asthma, and respiratory hypersensitivity reactions following use of nonsteroidal anti-inflammatory drugs (NSAIDs). In the setting of chronic respiratory disease, the type 2 inflammatory endotype is predominant in approximately 80% of patients with CRSwNP, rendering biologics directed against interleukin (IL)-4, IL­5, IL-13, and IgE of high clinical interest, particularly in patients with severe CRSwNP and NERD. NERD is often associated with CRSwNP and asthma. Patients with CRSwNP and NERD have been treated, among other therapies, with aspirin therapy after desensitization (ATAD). With the approval of monoclonal antibodies for CRSwNP and asthma, the question arises as to what extent ATAD, which is associated with undesirable side effects, is still useful in the treatment of CRSwNP. In this manuscript, the use of ATAD in CRSwNP patients is discussed from different medical and socioeconomic points of view, both alternatively to or in combination with monoclonal antibodies. Accordingly, both ATAD and biologics continue to play a supporting role in modern treatment of CRSwNP in NERD patients, and should be used judiciously to complement each other.

Lean methane combustion over zeolite-supported Pd catalysts: Structure-performance relationship and deactivation mechanism.

Zeolites are a promising support for Pd catalysts in lean methane (CH4) combustion. Herein, three types of zeolites (H-MOR, H-ZSM-5 and H-Y) were selected to estimate their structural effects and deactivation mechanisms in CH4 combustion. We show that variations in zeolite structure and surface acidity led to distinct changes in Pd states. Pd/H-MOR with external high-dispersing Pd nanoparticles exhibited the best apparent activity, with activation energy (Ea) at 73 kJ/mol, while Pd/H-ZSM-5 displayed the highest turnover frequency (TOF) at 19.6 × 10-3 sec-1, presumably owing to its large particles with more step sites providing active sites in one particle for CH4 activation. Pd/H-Y with dispersed PdO within pore channels and/or Pd2+ ions on ion-exchange sites yielded the lowest apparent activity and TOF. Furthermore, Pd/H-MOR and Pd/H-ZSM-5 were both stable under a dry condition, but introducing 3 vol.% H2O caused the CH4 conversion rate on Pd/H-MOR drop from 100% to 63% and that on Pd/H-ZSM-5 decreased remarkably from 82% to 36%. The former was shown to originate from zeolite structural dealumination, and the latter principally owed to Pd aggregation and the loss of active PdO.

Clustering-resistant Cu Single Atoms on Porous Au Nanoparticles Supported by TiO2 for Sustainable Photoconversion of CO2 into CH4.

Photocatalysts based on single atoms (SAs) modification can lead to unprecedented reactivity with recent advances. However, the deactivation of SAs-modified photocatalysts remains a critical challenge in the field of photocatalytic CO2 reduction. In this study, we unveil the detrimental effect of CO intermediates on Cu single atoms (Cu-SAs) during photocatalytic CO2 reduction, leading to clustering and deactivation on TiO2. To address this, we developed a novel Cu-SAs anchored on Au porous nanoparticles (CuAu-SAPNPs-TiO2) via a vectored etching approach. This system not only enhances CH4 production with a rate of 748.8 µmol·g-1·h-1 and 93.1% selectivity but also mitigates Cu-SAs clustering, maintaining stability over 7 days. This sustained high performance, despite the exceptionally high efficiency and selectivity in CH4 production, highlights the CuAu-SAPNPs-TiO2 overarching superior photocatalytic properties. Consequently, this work underscores the potential of tailored SAs-based systems for efficient and durable CO2 reduction by reshaping surface adsorption dynamics and optimizing the thermodynamic behavior of the SAs.

Metal Ion-Induced Large Fragment Deactivation: A Different Strategy for Site-Selectivity in a Complex Molecule.

Complex natural product functionalizations generally involve the use of highly engineered reagents, catalysts, or enzymes to react exclusively at a desired site through lowering of a select transition state energy. In this communication, we report a new, complementary strategy in which all transition states representing undesirable sites in a complex ionophore substrate are simultaneously energetically increased through the chelation of a metal ion to the large fragment we wish to neutralize. In the case of an electrophilic, radical based fluorination reaction, charge repulsion (electric field effects), induced steric effects, and electron withdrawal provide the necessary deactivation and proof of principle to afford a highly desirable natural product derivative. We envisage that many other electrophilic or charge based synthetic methods may be amenable to this approach as well.

Surface Carbon Formation and its Impact on Methane Dry Reforming Kinetics on Rhodium-based Catalysts by Operando Raman Spectroscopy.

A mechanism for carbon deposition and its impact on the reaction kinetics of Methane Dry Reforming (MDR) using Rhodium-based catalysts is presented. By integrating Raman spectroscopy with kinetic analysis in an operando-annular chemical reactor under strict chemical conditions, we discovered that carbon deposition on a Rh/α-Al2O3 catalyst follows a nucleation-growth mechanism. The dynamics of carbon aggregates at the surface is found to be ruled by the CO2/CH4 ratio and the inlet CH4 concentration. The findings elucidate the spatiotemporal development of carbon aggregates on the catalyst surface and their effects on catalytic performance. Furthermore, the proposed mechanism for carbon formation shows that the influence of CO2 on MDR kinetics is an indirect result of carbon accumulation over time frames exceeding the turnover frequency, thus reconciling conflicting reports in the literature regarding CO2's kinetic role in MDR.