Gas-Phase Neutral Binary Oxide Clusters: Distribution, Structure, and Reactivity toward CO

Neutral binary (vanadium–cobalt) oxide clusters are generated and detected in the gas phase for the first time. Their reactivities toward carbon monoxide (CO) are studied both experimentally and theoretically. Experimental results suggest that neutral VCoO₄ can react with CO to generate VCoO₃ and CO₂. Density functional theory studies show parallel results as well as provide detailed reaction mechanisms

OVX suppressed F-CPA but did not affect S-CPA.

<p>(A & B) Effects of OVX on formalin-induced CPA (F-CPA), as indicated by time spent in the treatment (formalin or normal saline)-paired compartment on preconditioning and postconditioning days (A) and CPA scores (the time spent in the treatment-paired compartment on the pre-conditioning day minus that on the post-conditioning day (B). (C & D) Effects of OVX on foot shock-induced CPA (S-CPA), as indicated by time spent in foot shock-paired compartment on preconditioning and postconditioning days (C) and CPA scores (D). ** p<0.01 versus preconditioning day. ^# p<0.05, ^## p<0.01.</p

Effects of OVX on depressive-like behaviors and spatial ability.

<p>(A & B) OVX rats displayed significantly more immobility (A) and less activity (B) time in FST. Subcutaneous injection of E2 (30 μg/day for 7 days) significantly attenuated immobility and prolonged activity time. * p<0.05, ** p<0.01. (C & D) OVX rats displayed fewer crossing (C) and rearing (D) numbers in OFT. E2 replacement increased crossing and rearing numbers in OFT. * p<0.05, ** p<0.01. E2 and vehicle were injected from the 4^th week after OVX, and behavioral tests were performed at the 5^th week. (E) Showing animal's escape latencies to find the submerged platform. Cutoff time was 60 s. (F) Showing animal's swimming speed in the training and testing trials. Morris water maze training consists of two training sessions of six trials each with a 30-min resting period between the two sessions. Memory retention was tested 24 h after training. The retention values are calculated as the mean of three-trial retention test. (G) Animal's escape latencies to find the visible platform. The platform was raised above the turbid liquid surface to be visible. FST, OFT and Morris water maze tests were performed at the 5^th week after OVX or sham-OVX surgery.</p

OVX enhanced formalin-induced nociceptive responses during phase 2 but did not affect CCI-induced mechanical allodynia.

<p>(A) OVX rats showed a higher formalin pain scores during phase 2. * p<0.05, ** p<0.01 versus sham. (B) Subcutaneous injection of E2 (30 μg/day for 7 days) significantly suppressed formalin pain scores during phase 2. * p<0.05, ** p<0.01 versus vehicle control. E2 and vehicle were injected from the 4^th week after OVX, and formalin test was performed at the 5^th week. (C) Both sham-OVX and OVX groups developed mechanical allodynia on day 7 after CCI. There was no significant difference in PWTs between sham and OVX rats. CCI surgery was performed at 4 weeks after sham-OVX or OVX. ^## p<0.01.</p

OVX induced mechanical allodynia and thermal hyperalgesia.

<p>(A & B) Effects of OVX on PWTs of both hindpaws. ** p<0.01 versus sham-OVX and intact. (C) Effects of 17β-estradiol (E2) or aequales vehicle (sesame oil) on PWTs of OVX rats. ** p<0.01 versus vehicle control; ## p<0.01 versus baseline. (D & E) Effects of OVX on TFLs of proximal and distal. * p<0.05; ** p<0.01 versus sham-OVX and intact. (F) Effects of E2 or aequales vehicle on TFLs of OVX rats. ** p<0.01 versus vehicle control; ## p<0.01 versus baseline. E2 (30 μg) was subcutaneously injected into OVX rats daily for 7 days from the 4^th week after OVX surgery. Behavioral tests were performed at the 5^th week. (F) Plasma estrogen concentration was significantly decreased after OVX. * p<0.05, ** p<0.01 versus proestrus stage; ^## p<0.01 versus diestrus and proestrus stage. (G) The uterine tube weight was attenuated at the 5^th week after OVX. (H) The body weight was significantly increased after OVX. ** p<0.01 versus sham-OVX and intact. P, proestrus stage; D, diestrus stage.</p

Schematic illustration for effects of OVX on variable behaviors.

<p>OVX facilitated acute pain and formalin tonic pain, attenuated pain-related negative emotion and produced depressive-like behaviors, but did not affect spatial ability and fear-related learning and memory.</p

Effects of estrous cycle on basal paw withdrawal threshould (PWT) to mechanical stimulation and tail-flick latency (TFL) to radiant heat stimulation.

<p>(A) PWTs of both hindpaws. (B) TFLs of proximal and distal. P, proestrus stage; E, Estrus stage; M, metaestrus stage; D, diestrus stage.</p

Gas-Phase Reactions of CF⁺ with Molecules of Interstellar Relevance

We have studied the gas-phase reactions of CF⁺ with 24 neutral species. Reaction rate constants and product branching fractions are measured at 298 K using a flowing afterglow-selected ion flow tube. Experimental work is supported by computational chemistry calculations to provide insight into the reactivity of classes of neutral molecules. Reactions of CF⁺ with small triatomic species and oxygen-containing organic molecules produce the stable molecule CO. The product branching fractions are discussed, and the potential energy surfaces for a few representative reactions are examined. CF⁺ is highly reactive with complex molecules and will likely be destroyed in dense environments in the interstellar medium. However, the lack of reactivity with small diatomic molecules will likely enable its survival in diffuse regions

Deprotonated Purine Dissociation: Experiments, Computations, and Astrobiological Implications

A central focus of astrobiology is the determination of abiotic formation routes to important biomolecules. The dissociation mechanisms of these molecules lend valuable insights into their synthesis pathways. Because of the detection of organic anions in the interstellar medium (ISM), it is imperative to study their role in these syntheses. This work aims to experimentally and computationally examine deprotonated adenine and guanine dissociation in an effort to illuminate potential anionic precursors to purine formation. Collision-induced dissociation (CID) products and their branching fractions are experimentally measured using an ion trap mass spectrometer. Deprotonated guanine dissociates primarily by deammoniation (97%) with minor losses of carbodiimide (HNCNH) and/or cyanamide (NH₂CN), and isocyanic acid (HNCO). Deprotonated adenine fragments by loss of hydrogen cyanide and/or isocyanide (HCN/HNC; 90%) and carbodiimide (HNCNH) and/or cyanamide (NH₂CN; 10%). Tandem mass spectrometry (MS^<i>n</i>) experiments reveal that deprotonated guanine fragments lose additional HCN and CO, while deprotonated adenine fragments successively lose HNC and HCN. Every neutral fragment observed in this study has been detected in the ISM, highlighting the potential for nucleobases such as these to form in such environments. Lastly, the acidity of abundant fragment ions is experimentally bracketed. Theoretical calculations at the B3LYP/6-311++G­(d,p) level of theory are performed to delineate the mechanisms of dissociation and analyze the energies of reactants, intermediates, transition states, and products of these CID processes

Reactions of Sulfur- and Oxygen-Containing Anions with Hydrogen Atoms: A Comparative Study

Reactions of hydrogen atoms with small sulfur-containing anions, SCN^–, CH₃COS^–, C₆H₅COS^–, ^–SCH₂COOH, C₆H₅S^–, 2-HOOCC₆H₄S^–, and related oxygen-containing anions, OCN^–, CH₃COO^–, C₆H₅COO^–, HOCH₂COO^–, C₆H₅O^–, 2-HOOCC₆H₄O^–, have been studied both experimentally and computationally. The experimental results show that associative electron detachment (AED) is the only channel for the reactions. The rate constants for reactions between sulfur-containing anions and H atoms are generally higher than for the related oxygen-containing anions with the exception of the reaction of SCN^–. The generally higher reactivity of the sulfur anions contrasts with previous results where AED reactivity was found to correlate with reaction exothermicity. Density functional theory calculations indicate that the reaction enthalpies, the characteristics of the reaction potential energy surfaces, and other structural and electronic factors can influence the reaction rate constants. This study indicates that organic sulfur anions can be more reactive than related oxygen anions in the interstellar medium where hydrogen atoms are abundant