Kinetics and Mechanism of the Thermal Decomposition of Sodium Percarbonate: Role of the Surface Product Layer

The reaction mechanism and overall kinetics of the thermal decomposition of sodium percarbonate crystals were investigated by thermoanalytical measurements and morphological observations. The reaction proceeds via a surface reaction and subsequent advancement of the as-produced reaction interface toward the center of the crystals, where the seemingly smooth mass-loss behavior can be described by the apparent activation energy <i>E</i>_a of ca. 100 kJ mol^–1. However, considering the rate behavior, as the reaction advances, it is expected that the secondary reaction step characterized by an autocatalytic rate behavior takes part in the overall reaction. The hindrance of the diffusional removal of the evolved gases by the surface product layer, Na₂CO₃, is the most probable reason for the change in the reaction mechanism. In the deceleration part of the first reaction step, the second reaction step is accelerated due to an increase in the water vapor pressure at the reaction interface inside the reacting particles. We also expect the self-generated reaction condition of the high water vapor pressure and the existence of liquid phase due to the formation of Na₂CO₃ whiskers as the solid product and the insensitive rate behavior of the second reaction step to a higher atmospheric water vapor pressure. A relevant reaction model for the thermal decomposition of SPC crystals are discussed by focusing on the role of the surface product layer

Stereocontrolled Solid-Phase Synthesis of Phosphate/Phosphoro­thioate (PO/PS) Chimeric Oligo­deoxy­ribonucleo­tides on an Automated Synthesizer Using an Oxazaphos­pholidine–Phosphoramidite Method

Stereocontrolled solid-phase synthesis of phosphate/phosphoro­thioate chimeric oligo­deoxy­ribonucleo­tides (PO/PS-ODNs) was achieved by integrating the conventional phosphoramidite method into a previously developed oxazaphospholidine method for the stereocontrolled synthesis of <i>P</i>-chiral oligonucleotides. <i>P</i>-Stereodefined PO/PS-ODNs with mixed sequences (up to 12-mers) were obtained in good yields and high stereoselectivities by reacting different combinations of monomers (conventional phosphoramidites/diastereopure nucleoside 3′-<i>O</i>-oxazaphos­pholidines), activators (ETT/CMPT), capping reagents (Pac₂O/CF₃COIm), and oxidizing/sulfurizing reagents (TBHP/POS) on an automated synthesizer. A thermal denaturation study examined the resultant diastereopure PO/PS-ODN 12-mers with three consecutive (<i>R</i>p)- or (<i>S</i>p)-PS-linkages at the internal or terminal regions of the molecules. We found that (<i>R</i>p)-PO/PS-ODNs can only moderately destabilize duplexes with complementary oligoribonucleotides (ORNs) compared with their unmodified ODN counterparts (Δ<i>T</i>_m = −0.4 °C per modification). In contrast, (<i>S</i>p)-PO/PS-ODNs have larger destabilizing effects (Δ<i>T</i>_m = −1.2 to −0.8 °C per modification). Although smaller destabilizing effects were observed when the (<i>S</i>p)-PS-linkages were incorporated into the terminal regions of the molecule, there was a weaker correlation between the location of an incorporated (<i>R</i>p)-PS-linkage and its destabilizing effect

Stereoselective Synthesis of <i>P</i>‑Modified α‑Glycosyl Phosphates by the Oxazaphospholidine Approach

α-Glycosyl phosphate derivatives are widely known as constituents of biomolecules. To date, several types of non-natural α-glycosyl phosphates including “<i>P</i>-modified analogs” have been synthesized to investigate their characteristics. Herein a new approach to the stereoselective modification of the intersugar phosphorus atom in α-glycosyl phosphates by use of the oxazaphospholidine method is presented. Via this approach, the dimers of α-glycosyl phosphorothioates and α-glycosyl boranophosphates were obtained efficiently and stereoselectively

Multistep Kinetic Behavior of the Thermal Decomposition of Granular Sodium Percarbonate: Hindrance Effect of the Outer Surface Layer

The kinetics and mechanism of the thermal decomposition of granular sodium percarbonate (SPC), which is used as a household oxygen bleach, were studied by thermoanalytical measurements under systematically changing conditions and morphological observation of the reactant solids at different reaction stages. A physico-geometrical kinetic behavior of the reaction that occurs in a core–shell structure composed of an outer surface layer and internal aggregates of SPC crystalline particles was illustrated through detailed kinetic analyses using the kinetic deconvolution method. Simultaneously, the hazardous nature of SPC as a combustion improver was evaluated on the basis of the kinetic behavior of the thermal decomposition. It was found that the outer surface layers of the SPC granules hinder the diffusional removal of product gases generated by the thermal decomposition of the internal SPC crystalline particles. The reaction rate decelerates because of an increase in the internal gaseous pressure as the reaction advances. However, the reaction rate accelerates once crack formation occurs in the outer surface layer at the midpoint of the reaction. Therefore, the overall reaction was empirically demonstrated to consist of two overlapping reaction steps owing to the changes in the self-generated reaction conditions in the interior of the SPC granules

Solid-Phase Synthesis of <i>P</i>‑Boronated Oligonucleotides by the <i>H</i>‑Boranophosphonate Method

Recently, <i>P</i>-boronated oligonucleotides have been attracting much attention as potential therapeutic oligonucleotides. In this study, we developed <i>H</i>-boranophosphonate oligonucleotide bearing a borano group and hydrogen atom on the internucleotidic phosphorus and demonstrated that this novel <i>P</i>-boronated oligonucleotide is a versatile precursor to various <i>P</i>-boronated oligonucleotides such as boranophosphate, boranophosphorothioate, and boranophosphoramidate. The method was also applicable to the synthesis of a locked nucleic acid-modified boranophosphate oligonucleotide, which exhibited a dramatically enhanced affinity to complementary oligonucleotides

Totally endoscopic pulmonary valve replacement

A 68-year-old man with a history of valve-sparing aortic root replacement and endoscopic aortic valve replacement was admitted to our hospital with dyspnea. Transthoracic echocardiography revealed severe pulmonary valve regurgitation. The patient had undergone cardiac surgery twice, through median sternotomy and right thoracotomy; therefore, we planned endoscopic pulmonary valve replacement via the left thoracic approach. The patient was placed in a modified right lateral decubitus position and underwent mild hypothermic cardiopulmonary bypass. An on-pump beating-heart technique was used during surgery. The 3D endoscopic system and trocars for surgical instruments were inserted through the left 3rd and 4th intercostal spaces. After incision of the pulmonary artery, the pulmonary cusps were resected. A 27-mm St Jude Medical Epic heart valve was implanted in the intra-annular position. Subsequently, the left atrial appendage was resected. The patient was discharged without complications. To our knowledge, this is the first case of totally endoscopic pulmonary valve replacement.</p

Solid-Phase Synthesis of Oligopeptides Containing Sterically Hindered Amino Acids on Nonswellable Resin Using 3‑Nitro-1,2,4-triazol-1-yl-tris(pyrrolidin-1-yl)phosphonium Hexafluorophosphate (PyNTP) as the Condensing Reagent

Peptides are still difficult to synthesize when they contain sterically hindered amino acids, such as α,α-disubstituted amino acids and N-substituted amino acids. In this study, solid-phase syntheses of oligopeptides containing multiple α-aminoisobutyric acid (Aib) residues were performed in high yields by using a nonswellable resin as the solid-support and 3-nitro-1,2,4-triazol-1-yl-tris­(pyrrolidin-1-yl)­phosphonium hexafluorophosphate (PyNTP) as the condensing reagent

Data_Sheet_1_Neutrophil phenotypes implicated in the pathophysiology of post-traumatic sepsis.docx

BackgroundThe disruption of immune homeostasis after trauma is a major cause of post-traumatic organ dysfunction and/or sepsis. Recently, a variety of neutrophil phenotypes with distinct functions have been identified and suggested as involved in various clinical conditions. The association between neutrophil phenotypes and post-traumatic immunodeficiency has also been reported, yet the specific neutrophil phenotypes and their functional significance in post-traumatic sepsis have not been fully clarified. Therefore, we sought to investigate neutrophil phenotypic changes in a murine model, as these may hold prognostic value in post-traumatic sepsis.Materials and methodsThird-degree burns affecting 25% of the body surface area were used to establish trauma model, and sepsis was induced 24 h later through cecal ligation and puncture (CLP). The Burn/CLP post-traumatic sepsis model and the Sham/CLP control model were established to assess the immunological status after trauma. Histopathological evaluation was performed on the spleen, liver, kidneys, and lung tissues. Immunological evaluation included the assessment of neutrophil markers using mass cytometry as well as cytokine measurements in serum and ascitic fluid through multiplex analysis using LUMINEX®.ResultsThe Burn/CLP group had a lower survival rate than the Sham/CLP group. Histopathological examination revealed an impaired immune response and more advanced organ damage in the Burn/CLP group. Furthermore, the Burn/CLP group exhibited higher levels of transforming growth factor-beta 1 in the blood and generally lower levels of cytokines than the Sham/CLP group. CD11b, which is involved in neutrophil adhesion and migration, was highly expressed on neutrophils in the Burn/CLP group. The expression of CD172a, which is related to the inhibition of phagocytosis, was also upregulated on neutrophils in the Burn/CLP group. The expression of sialic acid-binding lg-like lectin F and CD68 also differed between the two groups.ConclusionDifferent neutrophil phenotypes were observed between Burn/CLP and Sham/CLP groups, suggesting that neutrophils are implicated in the immune imbalance following trauma. However, further studies are needed to prove the causal relationships between neutrophil phenotypes and outcomes, including survival rate and organ dysfunction.</p

Additional file 1: Table S1. of Disseminated intravascular coagulation with increased fibrinolysis during the early phase of isolated traumatic brain injury

(XLSX 23 kb

Additional file 1: Table S1. of Disseminated intravascular coagulation with the fibrinolytic phenotype predicts the outcome of patients with out-of-hospital cardiac arrest

Numbers of the patients. (DOCX 48 kb