Enhanced Hydrogen Bonds of the (H2O)n (n = 4-8) Clusters Confined in Uranyl Peroxide Cluster Na20(UO2)20(O2)30.

Water is a basic resource and an essential component of living organisms. It often exhibits some novel properties under confinement. The water clusters (H2O)n (n = 4-8) confined in the cavity of uranyl peroxide cluster Na20(UO2)20(O2)30 (U20) have been computationally investigated by using ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT) calculations in this study. The results show that the confined water clusters can form hydrogen bonds with the internal oxygen atoms (Ouranyl) of U20, and their conformations changed significantly. The average lengths (2.553-2.645 Å) of hydrogen bonds in confined (H2O)n are shorter than those (2.731-2.841 Å) in the corresponding free water clusters. Moreover, these confined hydrogen bonds show better hydrogen bond patterns according to the quantified indices. The natural bond orbital (NBO) calculations determine that there is electron transferring from the U20 to its interior (H2O)n. It is the main reason for enhancing hydrogen bond interactions among the confined water molecules because their oxygen atoms are more negatively charged and their hydrogen atoms are more positively charged. The quantum theory of atoms in molecules (QTAIM) and interacting quantum atoms (IQA) analyses indicate that the confined hydrogen bonds are more covalent, based on the significant electron density ρ(r) and local energy density H(r) at the bond critical points (BCPs), and the stronger energies of interatomic exchange interactions (Vxc). These findings may help to promote the communication of confined water clusters and enrich the understating of confined hydrogen bonds.

An unnatural tripeptide structure containing intramolecular double H-bonds mimics a turn hairpin conformation.

A series of unnatural tripeptides, each consisting of two aromatic γ-amino acid residues and an ϖ-amino acid residue, are designed to probe their folding into hairpin conformations. The ϖ-amino acid residues, with aliphatic or aromatic spacers of different sizes, serve as the loop of the hairpins. Studies based on one-dimensional (1D) 1H NMR performed at different concentrations, solvent polarity, and temperature, along with 2D-NMR studies, demonstrated that the doubly H-bonded aromatic γ-amino acid residues play important roles in driving these tripeptides into the hairpin conformation. The loop based on 5-aminovaleric acid, which offers a four-carbon (CH2)4 spacer, enhanced the stability of the corresponding hairpin, while loops having a shorter, a longer and a more rigid spacer disfavored the formation of the hairpins. Results from computational studies are in good agreement with the experimental observations. Furthermore, the crystal structure of peptide 1b revealed the expected hairpin conformation in the solid state. This turn motif, which contains H-bonded aromatic γ-amino acid residues as the core unit and an ϖ-amino acid residue serving as the loop, provides a new platform that can be used to obtain a variety of turn conformations by incorporating diverse amino acids into the loops.

Effect of pad-fan cooling and dietary organic acid supplementation during late gestation and lactation on reproductive performance and antioxidant status of multiparous sows in hot weather.

A 2 × 2 factorial arrangement (rearing room with or without pad-fan cooling × diet with or without 2.5 kg/t organic acid) was used to evaluate the effect of pad-fan cooling and dietary organic acid supplementation during perinatal period on reproductive performance and antioxidant status of sows in hot weather. This study was conducted in a subtropical city in Guangdong Province in South China between August and October, 2015. At day 85 of gestation, a total of 112 sows were randomly assigned to the four treatments with 28 sows per treatment, and maintained until day 21 of lactation, and the feeding trial lasted for 51 days. During the experimental period, room temperature and humidity were recorded hourly. The lactation feed intake of sows (P = 0.109) and stillbirths (P < 0.05) increased when the sows were reared in the room with the pad-fan cooling against the room without pad-fan cooling. The number of weak newborns per litter and the malondialdehyde content in days 14 and 21 milk decreased (P < 0.05), while the lactation feed intake of sows, weaned litter weights, and individual pig weights increased when the sows were fed the organic acid (P < 0.05). In conclusion, pad-fan cooling in rearing room improved the lactation feed intake of sows, and dietary organic acid supplementation improved reproductive performance and milk antioxidant status of sows. Pad-fan cooling is recommended in farrowing room, but not in gestating room.

Application of flow-through flaps for replantation after traumatic limb amputation according to the angiosome concept.

OBJECTIVE: This study was performed to explore the treatment of the injury caused by traumatic limb amputation. METHODS: From October 2002 to October 2021, 30 cases were enrolled in the present study. The reasons for injury were as follows: 8 cases with single hydraulic column crush injury, 12 cases with gear and wire rope stranding, 6 cases with belt avulsion injury, and 4 cases with carbon block smash injury. The present study application of a free or small saphenous vein bypass to reconstruct the injured artery and vein according to the concept of the angiosome model. The defective vessels were bridged with the axial vessels of a flow-through flap, such as a medial calf flap or anterolateral femoral flap, to construct an additional blood supply and drainage vein for the severed limb. The clinical data of 30 cases with traumatic limb amputation of the lower leg and ankle were retrospectively analyzed. RESULTS: In all 30 cases of traumatic limb amputation, the replantation via the adoption of a flow-through flap was successful, and 85.6% of the patients remained in good postoperative condition. There were no symptoms of ischemia in the marginal segment after blood supply reconstruction of the transected limb by axial vascular bridging within the flap. CONCLUSION: Via the adoption of microsurgical techniques, the blood supply to the transected limb can be reconstructed by bridging the defective vessels with the adoption of the axial vessels of the flow-through flap is a feasible and advanced treatment option.

Neuron-protective effect of subanesthestic-dosage ketamine on mice of Parkinson's disease.

OBJECTIVE: To discuss the neuron-protective effect and possible mechanism of subanesthestic-dosage ketamine on Parkinson's disease mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. METHODS: A total of 30 mice were divided equally into three groups, model control group (MC group), ketamine treatment group (KT group), and blank control group (BC group), respectively. The Parkinson's disease mice of MC group and KT groups were established by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (20 mg/kg/d), while mice in KT group were treated by intraperitoneal injection of subanesthestic-dosage ketamine (8 mg/kg). Differences on behaviors and the number of nigra dopaminergic neurons of mice in each group were compared through the behavioral test and tyrosine hydroxylase immunohistochemistry experiments after the treatments. Furthermore, Western blot was used to test the expression of autophagy-related gene LC3-Ⅱ, Beclin1, Parkin, PINK1, and mTOR. RESULTS: Compared with the BC group, the neuroethology scores were lower and the amount of TH positive cells were less both in MC and MT groups; In KT group, the neuroethology scores were higher and the amount of tyrosine hydroxylase positive cells were significantly more than that in MC group (P < 0.05). Moreover, expression levels of autophagy-related proteins LC3-II, Beclin1, Parkin, and PINK1 were higher, while the mTOR expression level was lower than that in MC group. CONCLUSIONS: The subanesthestic-dosage ketamine has some protective effects on the coordinating ability of movement and cognitive ability of Parkinson's disease mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. This is probably due to that the autophagy activity of cells is activated by subanesthestic-dosage ketamine and that the neurons are protected.

Airway Humidification Reduces the Inflammatory Response During Mechanical Ventilation.

BACKGROUND: Currently, no clinical or animal studies have been performed to establish the relationship between airway humidification and mechanical ventilation-induced lung inflammatory responses. Therefore, an animal model was established to better define this relationship. METHODS: Rabbits (n = 40) were randomly divided into 6 groups: control animals, sacrificed immediately after anesthesia (n = 2); dry gas group animals, subjected to mechanical ventilation for 8 h without humidification (n = 6); and experimental animals, subjected to mechanical ventilation for 8 h under humidification at 30, 35, 40, and 45°C, respectively (n = 8). Inflammatory cytokines in the bronchi alveolar lavage fluid (BALF) were measured. The integrity of the airway cilia and the tracheal epithelium was examined by scanning and transmission electron microscopy, respectively. Peripheral blood white blood cell counts and the wet to dry ratio and lung pathology were determined. RESULTS: Dry gas group animals showed increased tumor necrosis factor alpha levels in BALF compared with control animals (P < .05). The tumor necrosis factor alpha and interleukin-8 levels in the BALF reached baseline levels when the humidification temperature was increased to 40°C. Scanning and transmission electron microscopy analysis revealed that cilia integrity was maintained in the 40°C groups. Peripheral white blood cell counts were not different among those groups. Compared with control animals, the wet to dry ratio was significantly elevated in the dry gas group (P < .05). Moreover, humidification at 40°C resulted in reduced pathologic injury compared with the other groups based on the histologic score. CONCLUSIONS: Pathology and reduced inflammation observed in animals treated at 40°C was similar to that observed in the control animals, suggesting that appropriate humidification reduced inflammatory responses elicited as a consequence of mechanical ventilation, in addition to reducing damage to the cilia and reducing water loss in the airway.