Comments on "Planar Tetracoordinate Hydrogen: Pushing the Limit of Multicentre Bonding"

In a recent communication (Angew. Chem. Int. Ed. 2024, 63, e202317312), Kalita et al. studied In4H+ system within the frame of single-reference approximation (SRA) and found that the global energy minimum (1 a) adopted the singlet state and a planar tetracoordinate hydrogen (ptH), while the second lowest isomer (1 b) located 3.0 kcal/mol above 1 a and adopted the triplet state as well as non-planar structure with a quasi-ptH. They assessed the reliability of SRA by checking the T1-diagnostic values of coupled cluster calculations. However, according to our multi-configurational second-order perturbation theory calculations at the CASPT2(12,13)/aug-cc-pVQZ (aug-cc-pVQZ-PP for In) level, both 1 a and 1 b exhibit obvious multi-referential characters, as reflected by their largest reference coefficients of 0.928 (86.1 %) and 0.938 (88.0 %), respectively. Moreover, 1 b is 5.05 kcal/mol lower than 1 a at this level, that is, what can be observed in In4H+ system is the quasi-ptH.

CBe4H6: a molecular rotor with a built-in on-off switch

It is highly challenging to control (stop and resume as needed) molecular rotors because their intramolecular rotations are electronically enabled by delocalized σ bonding, and the desired control needs to be able to destroy and restore such σ bonding, which usually means difficult chemical manipulation (substitution or doping atom). In this work, we report CBe4H6, a molecular rotor that can be controlled independently of chemical manipulation. This molecule exhibited the uninterrupted free rotation of Be and H atoms around the central carbon in first-principles molecular dynamics simulations at high temperatures (600 and 1000 K), but the rotation cannot be witnessed in the simulation at room temperature (298 K). Specifically, when a C-H bond in the CBe4H6 molecule adopts the equatorial configuration at 298 K, it destroys the central delocalized σ bonding and blocks the intramolecular rotation (the rotor is turned "OFF"); when it can adopt the axial configuration at 600 and 1000 K, the central delocalized σ bonding can be restored and the intramolecular rotation can be resumed (the rotor is turned "ON"). Neutral CBe4H6 is thermodynamically favorable and electronically stable, as reflected by a wide HOMO-LUMO gap of 7.99 eV, a high vertical detachment energy of 9.79 eV, and a positive electron affinity of 0.24 eV, so it may be stable enough for the synthesis, not only in the gas phase, but also in the condensed phase.

[The detecting value of virtual non-calcium technique of dual-energy CT for bone marrow edema around nontraumatic osteonecrosis of the femoral head]

Objective: To evaluate the value of virtual non-calcium (VNCa) technique of dual-energy CT (DECT) for detecting bone marrow edema (BME) around nontraumatic osteonecrosis of the femoral head (ONFH) using MRI as reference standard. Methods: Nontraumatic ONFH patients were prospectively studied in the Fourth Medical Center of Chinese PLA General Hospital from October 2022 to May 2023, and their MRI and DECT images were analyzed. The diagnostic efficiency of the subjective assessment of BME around ONFH by two radiologists in VNCa color-coded images were calculated using the MRI results as the reference standard. The BME ranges were compared between VNCa images and MRI. Traditional CT values and VNCa CT values were compared between normal bone marrow and BME. The receiver operator characteristic (ROC) curve was established based on the statistically different CT values, and the area under the curve (AUC) was calculated to find the threshold to distinguish normal bone marrow from BME and evaluate the diagnostic efficacy. Results: Thirty patients with ONFH were included, including 24 males and 6 females, aged (39±12) years. There were 18 bilateral hips and 12 unilateral hips, with a total of 48 hips, 34 hips of which showed BME on MRI. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of subjective detection of BME on VNCa color coded maps by two physicians were 97.1% (33/34) and 97.1% (33/34), 92.9% (13/14) and 71.4% (10/14), 97.1% (33/34) and 89.2% (33/37), 92.9% (13/14) and 90.9% (10/11), 95.8% (46/48) and 89.6% (43/48), respectively, with no statistical difference (all P>0.05).There was no statistical difference between VNCa color-coded images and MRI in the BME range (P=1.160). The traditional CT values measured by the two radiologists were in good agreement with VNCa CT values, with intraclass correlation coefficient (ICC) of 0.948 (95%CI: 0.908-0.971) and 0.982 (95%CI: 0.969-0.990), respectively. The traditional CT value of normal bone marrow was (400.7±82.8) HU, and that of BME was (443.7±65.7) HU, with no statistical difference (P=0.062). The VNCa CT value of normal bone marrow was (-103.1±27.8) HU, and that of BME was (-32.9±25.7) HU, with statistical difference (P<0.001). The AUC of distinguishing normal bone marrow from BME based on VNCa CT value was 0.958 (95%CI: 0.857-0.995). The best cut-off value was -74.5 HU, and when the VNCa CT value was higher than -74.5 HU, the sensitivity, specificity, PPV, NPV and accuracy of diagnosing BME were 97.1%, 92.9%, 97.1%, 92.9% and 95.8 %, respectively. Conclusion: The VNCa technique of DECT has high efficiency in detecting BME around ONFH, and can accurately demonstrate the range of BME.

Tetracoordinate or tricoordinate? Planar tetracoordinate nitrogen in the NBe4H4- cluster stabilized by multicenter bonds

Realization of planar tetracoordinate arrangements of nitrogen atoms is challenging because their preference for localized bonding (caused by its high electronegativity) makes them typically tricoordinate. This is especially true for the more electronegative oxygen atoms. Herein, we computationally designed two clusters NBe4H4- and OBe4H4; they contain a planar tetracoordinate nitrogen (ptN) and planar tetracoordinate oxygen (ptO) atom, respectively. Remarkably, the former is a dynamically stable global minimum, while the latter is not. The bonding analysis proves that planar tetracoordination in NBe4H4- favors over tricoordination because of the presence of multicenter delocalized bonds. In contrast, the planar tricoordination dominates due to its weak delocalized bonding ability of oxygen in the OBe4H4 cluster. Moreover, the 6σ/2π double aromaticity due to multicenter delocalized bonds allows the NBe4H4- cluster to obtain additional stability. This cluster is a promising synthetic due its dynamic and thermodynamic stability.

CB4Se5: a planar tetracoordinate carbon CB4 core stabilized by peripheral Se/Se2 bridges

Replacing one of the peripheral Se with a Se2 bridge is an effective strategy to flatten the C4v CB4Se4 cluster. The global minimum of CB4Se5 contains one fan-shaped planar tetracoordinate carbon (ptC) CB4 core, possessing double 2π + 6σ aromaticity. The peripheral Se2 bridge is dexterous and crucial for the stability of CB4Se5.

[Efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation in the treatment of secondary acute myeloid leukemia]

Objective: To evaluate the efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with secondary acute myeloid leukemia (sAML) . Methods: In this multicenter, retrospective clinical study, adult patients aged ≥18 years who underwent allo-HSCT for sAML at four centers of the Zhejiang Hematopoietic Stem Cell Transplantation Collaborative Group from January 2014 to November 2022 were included, and the efficacy and prognostic factors of allo-HSCT were analyzed. Results: A total of 95 patients were enrolled; 66 (69.5%) had myelodysplastic syndrome-acute myeloid leukemia (MDS-AML) , 4 (4.2%) had MDS/MPN-AML, and 25 (26.3%) had therapy-related AML (tAML) . The 3-year CIR, LFS, and overall survival (OS) rates were 18.6% (95% CI 10.2%-27.0%) , 70.6% (95% CI 60.8%-80.4%) , and 73.3% (95% CI 63.9%-82.7%) , respectively. The 3-year CIRs of the M-AML group (including MDS-AML and MDS/MPN-AML) and the tAML group were 20.0% and 16.4%, respectively (P=0.430) . The 3-year LFSs were 68.3% and 75.4%, respectively (P=0.176) . The 3-year OS rates were 69.7% and 75.4%, respectively (P=0.233) . The 3-year CIRs of the groups with and without TP53 mutations were 60.0% and 13.7%, respectively (P=0.003) ; the 3-year LFSs were 20.0% and 76.5%, respectively (P=0.002) ; and the 3-year OS rates were 40.0% and 77.6%, respectively (P=0.002) . According to European LeukmiaNet 2022 (ELN2022) risk stratification, the 3-year CIRs of patients in the low-, intermediate-, and high-risk groups were 8.3%, 17.8%, and 22.6%, respectively (P=0.639) . The three-year LFSs were 91.7%, 69.5%, and 65.6%, respectively (P=0.268) . The 3-year OS rates were 91.7%, 71.4%, and 70.1%, respectively (P=0.314) . Multivariate analysis revealed that advanced disease at allo-HSCT and TP53 mutations were independent risk factors for CIR, LFS, and OS. Conclusion: There was no significant difference in the prognosis of patients who underwent allo-HSCT among the MDS-AML, MDS/MPN-AML, and tAML groups. Advanced disease at transplantation and TP53 mutations were poor prognostic factors. ELN2022 risk stratification had limited value for predicting the prognosis of patients with sAML following allo-HSCT.

Planar Hexacoordinate Beryllium: Covalent Bonding Between s-block Metals

Achieving a planar hypercoordinate arrangement of s-block metals through covalent bonding with ligands is challenging due to the strong ionicity involved. Herein, we report the first case of a neutral binary global minimum containing a planar hexacoordinate beryllium atom. The central Be atom is coordinated by six active Be atoms, the latter in turn are enclosed by an equal number of more electronegative chlorine atoms in the periphery, forming a star-like phBe cluster (Be©Be6 Cl6 ). Importantly, the cluster exhibits dynamically stabilized stemming geometrically from the appropriate matching of metal-ligand size and electronically from adherence to the octet rule as well as possessing a 6σ/2π double aromaticity. Remarkably, energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) analysis reveals a significant covalent interaction between the ligand and the central metal beryllium atoms, a fact further supported by a large Wiberg bond index. This cluster is a promising synthetic as its excellent electronic, dynamic and thermodynamic stability.

[(OB)2-M©B7O7-BO]- (M = Mn, Tc, Re): Chemically Stable and Triply Aromatic Ballet Rotors

Single-molecule nanorotors are generally constructed based on boron atoms to obtain structural fluxionality via possessing the delocalized multicenter bonds. However, the electron-deficient boron atoms are commonly exposed in these nanorotors, which leads to extremely high chemical reactivity, which blocks the synthesis in the condensed phase. In this work, we computationally designed a series of transition-metal-doped boron oxide clusters MB10O10- (in structural configuration of [(OB)2-M©B7O7-BO]-, M = Mn, Tc, Re, © means "centered" in a planar or quasi-planar hypercoordinate environment), which can be vividly named as "ballet rotors" to label their anthropomorphic dynamic rotational behaviors. The rotational fluxionality in ballet rotors originates from the completely delocalized nature of the bonding within their MB10 core moieties. Remarkably, compared with single-molecule nanorotors having bare boron atoms and the narrow HOMO-LUMO gaps (≤4.00 eV) as well as low vertical detachment energies (VDEs, ≤4.46 eV for anions), the ballet rotors possess significantly improved chemical stability, as evidenced sterically by the absence of exposed boron atoms and electronically by much wider HOMO-LUMO gaps (5.66-5.98 eV) as well as obviously higher VDEs between 5.36 and 5.47 eV. Specifically, the ballet rotors are mainly stabilized by the delicately placed peripheral oxygen atoms, which can compensate for all electron-deficient boron atoms via O → B π back bonds and sterically protect them. Simultaneously, they are additionally stabilized by aromatic stabilization effect from possessing the novel S + P + D triple aromaticity. We expect that the proposal of chemically stable ballet rotors in this work can arouse the rational design of nanorotors for experimental realization in the condensed phase.

[Humanized anti-CD25 monoclonal antibody as a salvage therapy for steroid-refractory acute graft-versus-host disease after hematopoietic stem cell transplantation]

Objective: To investigate the efficacy of humanized anti-CD25 monoclonal antibody for steroid-refractory acute graft-versus-host disease (SR-aGVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Methods: A total of 64 patients with SR-aGVHD between June 2019 and October 2020 in Suchow Hopes Hematology Hospital were enrolled in this study. Humanized anti-CD25 monoclonal antibodies 1 mg·kg(-1)·d(-1) were administered on days 1, 3, and 8, and then once per week according to the disease progression. Efficacy was assessed at days 7, 14, and 28 after humanized anti-CD 25 treatment. Results: Of the 64 patients with a median age of 31 (15-63) years, 38 (59.4%) were male and 26 (40.6%) were female. The overall response (OR) rate of the humanized CD25 monoclonal antibody in 64 patients with SR-aGVHD on days 7, 14, and 28 were 48.4% (31/64), 53.1% (34/64), and 79.7% (51/64), respectively. Liver involvement is an independent risk factor for poor efficacy of humanized CD25 monoclonal antibody for SR-aGVHD at day 28 (OR=9.588, 95% CI 0.004-0.291, P=0.002). The median follow-up time for all patients was 17.1 (0.2-50.8) months from the start of humanized CD25 monoclonal antibody therapy. The 1- and 2-year OS rates were 63.2% (95% CI 57.1% -69.3%) and 52.6% (95% CI 46.1% -59.1%), respectively. The 1- and 2-year DFS rates were 58.4% (95% CI 52.1% -64.7%) and 49.8% (95% CI 43.4% -56.2%), respectively. The 1- and 2-year NRM rates were 28.8% (95% CI 23.1% -34.5%) and 32.9% (95% CI 26.8% -39.0%), respectively. The results of the multifactorial analysis showed that liver involvement (OR=0.308, 95% CI 0.108-0.876, P=0.027) and GVHD grade Ⅲ/Ⅳ (OR=9.438, 95% CI 1.211-73.577, P=0.032) were independent risk factors for OS. Conclusion: Humanized CD25 monoclonal antibody has good efficacy and safety for SR-aGVHD. This study shows that SR-aGVHD with pretreatment grade Ⅲ/Ⅳ GVHD and GVHD involving the liver has poor efficacy and prognosis and requires early intervention.

[Cs©C18]+ and [Na©C14]+: perfect planar alkaline-metal-centered polyynic cyclo[n]carbon complexes with record coordination numbers

Searching for the maximum coordination number (CN) in planar species with novel bonding patterns has fascinated chemists for many years. Using the experimentally observed polyynic cyclo[18]carbon D9h C18 and theoretically predicted polyynic cyclo[14]carbon D7h C14 as effective ligands and based on extensive first-principles theory calculations, we predict herein their perfect planar alkaline-metal-centered complexes D9h Cs©C18+ (1) and D7h Na©C14+ (4) which as the global minima of the systems possess the record coordination numbers of CN = 18 and 14 in planar polyynic species, respectively. More interestingly, detailed energy decomposition and adaptive natural density partitioning bonding analyses indicate that the hypercoordinate alkaline-metal centers in these complexes exhibit obvious transition metal behaviors, with effective in-plane (π-6s)σ, (π-7p)σ, and (π-5d)σ coordination bonds formed in Cs©C18+ (1) and (π-3s)σ, (π-3p)σ, and (π-3d)σ coordination interactions fabricated in Na©C14+ (4) to dominate the overall attractive interactions between the metal center and its cyclo[n]carbon ligand. Similarly, alkaline-metal-centered planar Cs Cs©C17B (2), C2v Cs©C17- (3), C2v Na©C13B (5), and C2v Na©C13- (6) have also been obtained with CN = 18, 17, 14, and 13, respectively.

[Sc©[3]CPP]+: A Viable Metal-Centered [3]Cycloparaphenylene

[n]Cycloparaphenylenes ([n]CPPs, n denotes the number of phenyl groups) are difficult to synthesize because of the strain related to their bent phenyl rings. In particular, the strain in [3]CPP is high enough to destroy the π electron delocalization, leading to the spontaneous structural transition to an energetically more stable "bond-shift" (BS) isomer ([3]BS). In this contribution, we propose to achieve [3]CPP by enhancing the π electron delocalization through hosting a guest metal atom. Our computations revealed that Sc could stabilize [3]CPP by forming the [Sc©[3]CPP]⁺ complex through the favorable π-Sc donation-backdonation interactions. Thermodynamically, the binding energy between the Sc atom and [3]CPP was -205.7 kcal/mol, which could well compensate not only the energy difference of 44.2 kcal/mol between [3]CPP and [3]BS but also the extremely high strain energy of 170.3 kcal/mol in [3]CPP. Simultaneously, the [Sc©[3]CPP]⁺ complex is stable up to 1500 K in dynamic simulations, suggesting its high viability in the synthesis.

How hexafluoroisopropanol solvent promotes Diels-Alder cycloadditions: ab initio metadynamics simulations

The solvent effects in Diels-Alder cycloadditions were studied by using ab initio molecular dynamics simulations with explicit molecular treatments for both substrates and solvents. Energy decomposition analysis was used to investigate the role of H-bonding networks of hexafluoroisopropanol solvent in promoting both reactivity and regioselectivity.

Ab Initio Metadynamics Simulations of Hexafluoroisopropanol Solvent Effects: Synergistic Role of Solvent H-Bonding Networks and Solvent-Solute C-H/π Interactions

The solvent effects in Friedel-Crafts cycloalkylation of epoxides and Cope rearrangement of aldimines were investigated by using ab initio molecular dynamics simulations. Explicit molecular treatments were applied for both reactants and solvents. The reaction mechanisms were elucidated via free energy calculations based on metadynamics simulations. The results reveal that both reactions proceed in a concerted fashion. Key solvent-substrate interactions are identified from the structures of transition states with explicit solvent molecules. The remarkable promotion effect of hexafluoroisopropanol solvent is ascribed to the synergistic effect of H-bonding networks and C-H/π interactions with substrates.

3-D molecular stars with covalent axial bonding

In designing three-dimensional (3-D) molecular stars, it is very difficult to enhance the molecular rigidity through forming the covalent bonds between the axial and equatorial groups because corresponding axial groups will generally break the delocalized π bond over equatorial frameworks and thus break their star-like arrangement. In this work, exemplified by designing the 3-D stars Be₂ ©Be₅ E₅ ⁺ (E = Au, Cl, Br, I) with three delocalized σ bonds and delocalized π bond over the central Be₂ ©Be₅ moiety, we propose that the desired covalent bonding can be achieved by forming the delocalized σ bond(s) and delocalized π bond(s) simultaneously between the axial groups and equatorial framework. The covalency and rigidity of axial bonding can be demonstrated by the total Wiberg bond indices of 1.46-1.65 for axial Be atoms and ultrashort Be-Be distances of 1.834-1.841 Å, respectively. Beneficial also from the σ and π double aromaticity, these mono-cationic 3-D molecular stars are dynamically viable global energy minima with well-defined electronic structures, as reflected by wide HOMO-LUMO gaps (4.68-5.06 eV) and low electron affinities (4.70-4.82 eV), so they are the promising targets in the gas phase generation, mass-separation, and spectroscopic characterization.

Origins of Regioselectivity in CuH-Catalyzed Hydrofunctionalization of Alkenes

Factors controlling the regioselectivity in alkene hydrocupration were computationally investigated using energy decomposition analysis. The results demonstrate that the Markovnikov-selective hydrocupration with electronically activated mono-substituted olefins is mostly affected by the destabilizing Pauli repulsion, which is due to the electron delocalization effect. The anti-Markovnikov-selective hydrocupration with 1,1-dialkyl-substituted terminal olefins is dominated by the repulsive electrostatic interactions, which is because of the unequal π electron distribution caused by the induction effect of alkyl substituents.

Weak Electrostatic Interactions with Bisphosphine Ligands Facilitate Reductive Elimination of PhCF3 from Pd(II) Complexes

The origins of ligand effects on PhCF₃ reductive elimination from Pd^II complexes were computationally investigated by using energy decomposition analysis. The results indicate weak electrostatic interactions between ligands and Ph-Pd-CF₃ lead to small barriers of PhCF₃ reductive elimination. Two major factors affecting the electrostatic interactions are identified.

Origins of regioselectivity in Ni-catalyzed hydrofunctionalization of alkenes via ligand-to-ligand hydrogen transfer mechanism

The origins of regioselectivity in Ni-catalyzed alkene hydrofunctionalizations were computationally investigated by using energy decomposition analysis. The results indicate the Markovnikov selectivity with aryl-substituted alkenes is favored due to the stabilizing charge transfer effect, and the anti-Markovnikov selectivity with alkyl-substituted alkenes is favored because of the destabilizing Pauli repulsion effect.

Probing ^{93m}Mo Isomer Depletion with an Isomer Beam

The isomer depletion of ^{93m}Mo was recently reported [Chiara et al., Nature (London) 554, 216 (2018)NATUAS0028-083610.1038/nature25483] as the first direct observation of nuclear excitation by electron capture (NEEC). However, the measured excitation probability of 1.0(3)% is far beyond the theoretical expectation. In order to understand the inconsistency between theory and experiment, we produce the ^{93m}Mo nuclei using the ^{12}C(^{86}Kr,5n) reaction at a beam energy of 559 MeV and transport the reaction residues to a detection station far away from the target area employing a secondary beam line. The isomer depletion is expected to occur during the slowdown process of the ions in the stopping material. In such a low γ-ray background environment, the signature of isomer depletion is not observed, and an upper limit of 2×10^{-5} is estimated for the excitation probability. This is consistent with the theoretical expectation. Our findings shed doubt on the previously reported NEEC phenomenon and highlight the necessity and feasibility of further experimental investigations for reexamining the isomer depletion under low γ-ray background.

[Safety and efficacy of left atrial appendage closure combined with patent foramen ovale closure for atrial fibrillation patients with patent foramen ovale]

Objective: To analyze the safety and efficacy of combined left atrial appendage (LAA) and patent foramen ovale (PFO) closure in adult atrial fibrillation (AF) patients complicating with PFO. Methods: This study is a retrospective and cross-sectional study. Seven patients with AF complicated with PFO diagnosed by transesophageal echocardiography (TEE) in Zhoupu Hospital Affiliated to Shanghai University of Medicine & Health Sciences from June 2017 to October 2020 were selected. Basic data such as age, gender and medical history were collected. The atrial septal defect or PFO occluder and LAA occluder were selected according to the size of PFO, the ostia width and depth of LAA. Four patients underwent left atrial appendage closure(LAAC) and PFO closure at the same time. PFO closure was performed during a one-stop procedure of cryoablation combined with LAAC in 2 patients. One patient underwent PFO closure at 10 weeks after one-stop procedure because of recurrent transient ischemic attack (TIA). All patients continued to take oral anticoagulants. TEE was repeated 8-12 weeks after intervention. In case of device related thrombus(DRT), TEE shall be rechecked 6 months after adjusting anticoagulant and antiplatelet drug treatment. Patients were follow-up at 1, 3, 6, 12, 24 months by telephone call, and the occurrence of cardio-cerebrovascular events was recorded. Results: Among the 7 patients with AF, 2 were male, aged (68.0±9.4) years, and 3 had a history of recurrent cerebral infarction and TIA. Average PFO diameter was (3.5±0.8)mm. Three patients were implanted with Watchman LAA occluder (30, 30, 33 mm) and atrial septal defect occluder (8, 9, 16 mm). 2 patients were implanted with LAmbre LAA occluder (34/38, 18/32 mm) and PFO occluder (PF1825, PF2525). 2 patients were implanted with LACbes LAA occluder (24, 28 mm) and PFO occluder (PF2525, PF1825) respectively. The patients were followed up for 12 (11, 24) months after operation. TEE reexamination showed that the position of LAA occluder and atrial septal defect occluder or PFO occluder was normal in all patients. DRT was detected in 1 patient, and anticoagulant therapy was adjusted in this patient. 6 months later, TEE showed that DRT disappeared. No cardiovascular and cerebrovascular events occurred in all patients with AF during follow-up. Conclusions: In AF patients complicated with PFO, LAAC combined with PFO closure may have good safety and effectiveness.

Planar pentacoordinate carbon in a sulphur-surrounded boron wheel: the global minimum of CB5S5. Chem Commun (Camb) 2022;58:2552-2555. [PMID: 35103735 DOI: 10.1039/d1cc07313c]

We report a σ + π double aromatic CB₅S₅⁺ cluster, the first global minimum unusually having a planar hypercoordinate carbon inside a boron wheel. Five peripheral sulfur atoms stabilize the carbon-centered boron wheel by weakening the electron deficiency of the boron atoms through strong S → B π back-bonding.

Prediction of heptagonal bipyramidal nonacoordination in highly viable [OB-M©B7O7-BO]- (M = Fe, Ru, Os) complexes

Non-spherical distributions of ligand atoms in coordination complexes are generally unfavorable due to higher repulsion than for spherical distributions. To the best of our knowledge, non-spherical heptagonal bipyramidal nonacoordination is hitherto unreported, because of extremely high repulsion among seven equatorial ligand atoms. Herein, we report the computational prediction of such nonacoordination, which is constructed by the synergetic coordination of an equatorial hepta-dentate centripetal ligand (B₇O₇) and two axial mono-dentate ligands (-BO) in the gear-like mono-anionic complexes [OB-M©B₇O₇-BO]^- (M = Fe, Ru, Os). The high repulsion among seven equatorial ligand B atoms has been compensated by the strong B-O bonding. These complexes are the dynamically stable (up to 1500 K) global energy minima with the HOMO-LUMO gaps of 7.15 to 7.42 eV and first vertical detachment energies of 6.14 to 6.66 eV (being very high for anions), suggesting their high probability for experimental realization in both gas-phase and condensed phases. The high stability stems geometrically from the surrounded outer-shell oxygen atoms and electronically from meeting the 18e rule as well as possessing the σ + π + δ triple aromaticity. Remarkably, the ligand-metal interactions are governed not by the familiar donation and backdonation interactions, but by the electrostatic interactions and electron-sharing bonding.

[Medium and long-term follow-up of the Pul-Stent in treating postoperative branch pulmonary artery stenosis in children with congenital heart disease]

Objective: To evaluate the effectiveness and safety of Pul-Stent as the treatment of postoperative branch pulmonary artery stenosis in children with congenital heart disease. Methods: This was a retrospective study. Thirty-three patients who underwent Pul-Stent implantation in Shanghai Children's Medical Center due to postoperative residual pulmonary artery stenosis from August 2014 to June 2015 were included. The immediate curative effect, follow-up and complications of Pul-Stent implantation were assessed. Comparisons between groups were performed with unpaired Student t test. Results: Pul-Stent implantation of 33 patients (19 males and 14 females) were performed successfully. Thirty-one patients underwent percutaneous stenting, and 2 patients underwent hybrid stenting. A total of 35 Pul-Stents were implanted (19 of model small, 15 of model medium and one of model large), 23 stents were planted in the proximal left pulmonary artery and 12 stents were in the proximal right pulmonary artery. The initial diameter of dilation balloon ranged from 6 to 16 mm, and the long sheath of percutaneous implantation ranged from 8 to 10 F in 29 patients (29/31, 94%). After stenting, the diameter of the narrowest segment of pulmonary artery increased from (4.0±1.7) mm to (9.1±2.1) mm in all patients (t=-21.60, P<0.001). The pressure gradient at the stenosis in 26 patients after biventricular correction decreased from (30.5±12.3) mmHg (1 mmHg=0.133 kPa) to (9.9±9.6) mmHg (t=12.92, P<0.001), and the right ventricular to aortic pressure ratio decreased from 0.57±0.14 to 0.44±0.12 (t=7.44, P<0.001). The pressure of the superior vena cava after stenting in 5 patients after cavopulmonary anastomosis decreased from (17.0±1.9) mmHg to (14.0±0.7) mmHg (t=2.86, P=0.046). Two patients died during reoperation for repairing other cardiac malformations. The remaining 31 patients were clinically stable during the follow-up period of (5.3±1.6) years, and one stent fracture was found on chest X-ray. Cardiac catheterization reexaminations in 16 patients showed that restenosis was found in one stent, while stent position and patency were satisfactory in the remaining stents. Nine children underwent post-dilation without stent fracture, displacement or aneurysm formation. Cardiac tomography showed no stent stenosis, fracture observed, or significant change in diameter of the stent in 8 patients. The inner diameter and pulmonary blood perfusion could not be accurately evaluated due to artifacts by cardiac magnetic resonance imaging in 4 patients. Conclusions: Pul-Stent has good compliance and adequate radial strength, and can dilate further over time to accommodate for somatic growth. It performs safely and effectively in treating post-operative branch pulmonary artery stenosis in children.

How the electron-deficient Cp ligand facilitates Rh-catalyzed annulations with alkynes

The dominant factors for the CpX ligand effects (Cp* versus CpE) on the reactivity for alkyne insertion into cationic and neutral rhodacycles are identified based on energy decomposition analysis.

Origins of regio- and stereoselectivity in Cu-catalyzed alkyne difunctionalization with CO2 and organoboranes

The anti-to-Cu 1,2-migration of alkynyl boronates is critical for the 1,1-E-selective difunctionalization of terminal alkynes with CO2 and organoboranes.

Origin of Ligand Effects on Stereoinversion in Pd-Catalyzed Synthesis of Tetrasubstituted Olefins

The mechanism and origin of ligand effects on stereoinversion of Pd-catalyzed synthesis of tetrasubstituted olefins were investigated using DFT calculations and the approach of energy decomposition analysis (EDA). The results reveal that the stereoselectivity-determining steps are different when employing different phosphine ligands. This is mainly due to the steric properties of ligands. With the bulkier Xantphos ligand, the syn/anti-to-Pd 1,2-migrations determine the stereoselectivity. While using the less hindered P(o-tol)₃ ligand, the 1,3-migration is the stereoselectivity-determining step. The EDA results demonstrate that Pauli repulsion and polarization are the dominant factors for controlling the stereochemistry in 1,2- and 1,3-migrations, respectively. The origins of differences of Pauli repulsion and polarization between the two stereoselective transition states are further identified.

M©B7O7+ (M = Ni, Pd, Pt): aromatic molecular stars with a planar heptacoordinate transition metal

The dynamically stable global minima M©B₇O₇⁺ (M = Ni, Pd, Pt) are interesting in that they possess σ-aromaticity alone within the B₇M core moiety, which can be attributed to the strong peripheral localized O → B π back-bonding that leads to the less favourable delocalized M → B π back-bonding over the B₇M core moiety.

Computational study of silver-catalyzed stereoselective hydroalkylation of alkynes: Pauli repulsion controlled Z/E selectivity

The mechanism and origin of stereoselectivity of silver-catalyzed hydroalkylation of alkynes were computationally investigated at the B3LYP-D3BJ/6-311+G(d,p)-SDD//B3LYP/6-31G(d)-LANL2DZ level. The complex of alkynyl trialkylboronate with cationic silver is a key intermediate, which triggers the rate- and stereoselectivity-determining 1,2-migration step. Energy decomposition analysis indicates that the difference of Pauli repulsion dominates the stereoselectivity.

Transition metal chemistry in synthetically viable alkaline earth complexes M(Cp)3- (M = Ca, Sr, Ba)

We predicted the stable alkaline earth complexes M(Cp)3- (M = Ca, Sr, Ba; Cp = cyclopentadienyl), where the M centers were in their stable +2 oxidation state and mimicked the bonding behaviour of transition metals by participating in bonding with the π orbitals of Cp ligands using their d orbitals.

Syntheses, crystal structures, and biological evaluations of new dinuclear platinum(ii) complexes with 1,2,4-triazole derivatives as bridging ligands

A series of new dinuclear platinum(ii) complexes with the general formula [Pt₂(μ-HL)₄] (1-4), where H₂L is 4-[(5-chloro-2-hydroxy-benzylidene)-amino]-3-R-1,2,4-triazole-5-thione: R = H (1), methyl (2), ethyl (3) and propyl (4), were synthesized and characterized. The X-ray crystal structures of 2, 3 and 4 reveal that the two platinum atoms form a paddlewheel core with four chelating triazole ligands as bridges, revealing a radically different structure than those of the traditional anticancer platinum(ii) complexes. These complexes show higher in vitro antiproliferative activity against human liver hepatocellular carcinoma (HepG2) and human breast adenocarcinoma (MCF7) than human lung cancer (A549) and human normal hepatocyte (HL-7702) cell lines. In particular, 3 exhibits antiproliferative activity (IC₅₀ = 5.5 μM) against HepG2 cells comparable to that of cisplatin. Different from the traditional anticancer platinum(ii) complexes with high DNA affinity, 3 binds very weakly to DNA. Upon comparison, it exhibits potent inhibiting activity against protein tyrosine phosphatases 1B (PTP1B, IC₅₀ = 16 μM) through possible binding to its active sites and its binding constant is 5.28 × 10⁴ M^-1. The results suggest that the antiproliferative mechanism of 3 against HepG2 cells may be different from that of cisplatin.

Ultra-brilliant GeV betatronlike radiation from energetic electrons oscillating in frequency-downshifted laser pulses

Electrons can be accelerated to GeV energies with high collimation via laser wakefield acceleration in the bubble regime and emit bright betatron radiation in a table-top size. However, the radiation brightness is usually limited to the third-generation synchrotron radiation facilities operating at similar photon energies. Using a two-stage plasma configuration, we propose a novel scheme for generating betatronlike radiation with an extremely high brilliance. In this scheme, the relativistic electrons inside the bubble injected from the first stage can catch up with the frequency-downshifted laser pulse formed in the second stage. The laser red shift originates from the phase modulation, together with the group velocity dispersion, which enables more energy to be transfered from the laser pulse to γ-photons, giving rise to ultra-brilliant betatronlike radiation. Multi-dimensional particle-in-cell simulations indicate that the radiated γ-photons have the cut-off energy of GeV and a peak brilliance of 10²⁶ photons s^-1 mm^-2 mrad^-2 per 0.1%BW at 1 MeV, which may have diverse applications in various fields.

Nitrogen versus carbon in planar pentacoordinate environments supported by Be5Hn rings

Nitrogen is a better fit for Be₅H_n rings, both geometrically and electronically, than carbon, leading to the viable planar pentacoordinate nitrogen species.

Mechanism of nickel-catalyzed direct carbonyl-Heck coupling reaction: the crucial role of second-sphere interactions

We present a detailed DFT mechanistic study on the first Ni-catalyzed direct carbonyl-Heck coupling of aryl triflates and aldehydes to afford ketones. The precatalyst Ni(COD)2 is activated with the phosphine (phos) ligand, followed by coordination of the substrate PhOTf, to form [Ni(phos)(PhOTf)] for intramolecular PhOTf to Ni(0) oxidative addition. The ensuing phenyl-Ni(ii) triflate complex substitutes benzaldehyde for triflate by an interchange mechanism, leaving the triflate anion in the second coordination sphere held by Coulomb attraction. The Ni(ii) complex cation undergoes benzaldehyde C[double bond, length as m-dash]O insertion into the Ni-Ph bond, followed by β-hydride elimination, to produce Ni(ii)-bound benzophenone, which is released by interchange with triflate. The resulting neutral Ni(ii) hydride complex leads to regeneration of the active catalyst following base-mediated deprotonation/reduction. The benzaldehyde C[double bond, length as m-dash]O insertion is the rate-determining step. The triflate anion, while remaining in the second sphere, engages in electrostatic interactions with the first sphere, thereby stabilizing the intermediate/transition state and enabling the desired reactivity. This is the first time that such second-sphere interaction and its impact on cross-coupling reactivity has been elucidated. The new insights gained from this study can help better understand and improve Heck-type reactions.

Origins of Lewis acid acceleration in nickel-catalysed C–H, C–C and C–O bond cleavage

The effects of charge transfer, Pauli repulsion and electrostatics/polarization are identified as dominant factors for Lewis acid accelerations in Ni-catalyzed C–X (X = H, C and O) bond cleavages.

Influence of stepwise oxidation on the structure, stability, and properties of planar pentacoordinate carbon species CAl5. Phys Chem Chem Phys 2020;22:17062-17067. [PMID: 32568316 DOI: 10.1039/d0cp01106a]

Computational design has played an important role in planar hyper-coordinate carbon (phC) chemistry. However, none of numerous computationally predicted phC species were subsequently successfully synthesized in the condensed phase, perhaps due to the frustrating issue of oxidation. In the present work, we studied the influence of stepwise oxidation on the structure, stability, and properties of phC species using the milestone planar pentacoordinate carbon (ppC) species CAl₅⁺ as an example. Our results indicated that the ppC structure of CAl₅⁺ would be directly destroyed with one, two, or six O atom(s) per molecule present and indirectly with three or four O atoms, but maintained with five O atoms due to the ppC isomer of CAl₅O₅⁺ being a kinetically stable global energy minimum displaying σ and π double aromaticity. Moreover, the magnitudes of the first to fifth vertical oxygen affinities (VOAs) for CAl₅⁺ were determined to be very high (-85.5 to -116.3 kcal mol^-1), probably due to the existence of peripheral diffuse Al-Al bond(s). However, the sixth VOA was reduced significantly to -50.2 kcal mol^-1, consistent with the absence of any diffuse Al-Al bond in the corresponding CAl₅O₅⁺ species. So CAl₅O₅⁺ may be insensitive to oxidation. Therefore, the ppC species D_5h CAl₅O₅⁺ might be resistant to being degraded under a delicate control of oxidation level (producing five O atoms per CAl₅⁺ molecule).

The feasibility of enzyme hydrolysate gross energy for formulating duck feeds

Two experiments were designed to investigate the feasibility of enzyme hydrolysate gross energy (EHGE) for formulating duck feeds. In experiment 1, six mixed diets and 6 experimental diets (compound feeds) with 20% CP were formulated, and their EHGE, AME, and TME were determined so as to analyze the correlation between EHGE and AME, TME. In experiment 2, six experimental diets with different EHGE levels were further arranged to determine the EHGE requirement for Pekin ducks from hatch to 21 D of age. A total of 384 freshly hatched ducklings was randomly divided into 6 experimental treatments, each treatment containing 8 replicates with 8 ducks per replicate. The results showed that there were a linear correlation between EHGE and AME (r = 0.998, P < 0.01), TME (r = 0.997, P < 0.01) for 6 mixed diets, and the regression models were AME = 0.996 × EHGE−1.062 (R² = 0.996, P < 0.01), TME = 0.997 × EHGE+0.304 (R² = 0.995, P < 0.01). For the 6 experimental diets, EHGE was also positively correlated with AME (r = 0.983, P < 0.01), TME (r = 0.984, P < 0.01), and the regression models were AME = 1.2054 × EHGE−3.180 (R² = 0.967, P < 0.01), TME = 1.2054 × EHGE−1.783 (R² = 0.967, P < 0.01). According to the broken-line model and optimal BW, the EHGE requirement for ducks from hatch to 21 D of age was 2,937 kcal/kg (calculated value), 3,182 kcal/kg (determined value). In conclusion, EHGE could be used to predict the AME and TME values for mixed diets and compound feeds based on established regression models, and the simulated digestion method in vitro has the potential for effective energy evaluation and formulation for duck feeds.

The antibiofilm and collagen-stabilizing effects of proanthocyanidin as an auxiliary endodontic irrigant

AIM

To evaluate the antibiofilm effect of proanthocyanidin (PA) solution as an irrigant against Enterococcus faecalis (E. faecalis) and its influence on the mechanical properties and biodegradation resistance of demineralized root dentine.

METHODOLOGY

Enterococcus faecalis were introduced into human root dentine tubules by a serial centrifugation method and grown for 1 week. Dentine blocks infected with 1-week-old E. faecalis biofilms were treated with the following irrigants: sterile water (control), 2% chlorhexidine (CHX), 2% PA, 5% PA and 10% PA. After treatment, the live and dead bacteria proportions within E. faecalis biofilms were analysed using confocal laser scanning microscopy. To evaluate the biostability of fully demineralized dentine treated by the aforementioned irrigants, the elastic modulus and hydroxyproline release of human dentine incubated in collagenase solution were tested at baseline, after irrigant treatment and after biodegradation, respectively. Furthermore, the surface chemical bond of demineralized dentine collagen treated by various irrigants was characterized by X-ray photoelectron spectroscopy (XPS). Statistical analysis was performed using one-way anova and Tukey's post hoc multiple comparisons with the significance level at 5%.

RESULTS

The proportion of dead E. faecalis volume was significantly higher in the PA and CHX groups than that in the control group (P < 0.05). PA irrigation significantly increased the mechanical properties of demineralized dentine (P < 0.05), and the effect was enhanced with increasing PA concentration. CHX and PA groups had significantly less elasticity loss and hydroxyproline release (P < 0.05). The biomodification of dentine collagen by PA was verified by increased C-O/C-N peak percentage under C1s and C-O peak percentage under O1s narrow-scan XPS spectra.

CONCLUSIONS

Proanthocyanidin killed E. faecalis within biofilms and enhanced the biostability of the collagen matrix of demineralized root dentine. It might be used as an auxiliary endodontic irrigant with antibiofilm and collagen-stabilizing effects.

Research Note: Effects of riboflavin on reproductive performance and antioxidant status of duck breeders

An experiment was conducted to investigate the effects of dietary riboflavin levels on reproductive performance, riboflavin status, and antioxidant status of laying duck breeders, to estimate the requirement of this vitamin for duck breeders. Different levels crystalline riboflavin (0, 2.5, 5, 10, and 15 mg/kg) were supplemented to a corn-soybean-corn gluten meal basal diet to produce 5 dietary treatments with different analyzed total riboflavin levels (1.48, 3.20, 6.30, 11.71, and 16.83 mg/kg). A total of 80 White Pekin duck breeders aged 40 wk were allotted to 5 dietary treatments of 16 birds each (8 replicates per treatment and 2 breeders per replicate), and all birds were raised individually for 9 wk. At the end of the experiment, reproductive performance, tissue riboflavin concentrations, and antioxidant status of White Pekin duck breeders were measured. The results showed that body weight, egg weight, egg production, and egg fertility were not affected by dietary riboflavin levels. However, among all of the laying duck breeders, the birds fed the basal diet without riboflavin supplementation had the lowest egg hatchability, plasma riboflavin, egg yolk riboflavin, and egg albumen riboflavin (P < 0.001). In addition, the duck breeders fed the basal diet without riboflavin supplementation showed the lowest antioxidant capacity indicated by greatest plasma malondialdehyde (MDA) content and lowest reduced glutathione content, total superoxide dismutase (T-SOD) activities, and total antioxidant capacity in both plasma (P < 0.001) and egg yolk (P < 0.001). These results revealed that dietary riboflavin supplementation improved the reproductive performance and antioxidant status of the duck breeders. According to the broken-line model, the riboflavin requirements (based on dietary total riboflavin) of laying duck breeders in terms of the egg hatchability, plasma riboflavin, egg yolk riboflavin, egg albumen riboflavin, plasma T-SOD activity, and plasma MDA content were 3.19, 7.42, 3.88, 7.44, 6.45, and 8.84 mg/kg, respectively.

Effects of dietary energy and methionine on growth performance and carcass traits of growing Pekin ducks from 15 to 42 days of age

A 2 × 5 factorial experiment, using 2 dietary metabolizable energy (ME) levels (10.82, 12.95 MJ/kg) and 5 supplemental methionine (Met) levels (0, 0.075, 0.15, 0.225, and 0.30%), was conducted to investigate the effects of dietary energy and Met levels on growth performance and carcass traits of Pekin ducks from 15 to 42 D of age. A total of 300 15-day-old male Pekin ducks were randomly allocated to 10 groups with 6 replicates in each group and 5 ducks per replicate. The results showed that ducks those fed the basal diets without Met supplementation had poor growth performance. The ADG was increased (P < 0.001), and the ADFI and feed conversion ratio (FCR) decreased (P < 0.001) when Met were supplemented in diets. The ADFI and FCR were decreased (P < 0.001), while ADG was not affected (P > 0.05) when dietary ME level increased from 10.82 to 12.95 MJ/kg. Dietary Met supplementation increased the yields of eviscerated carcass (P = 0.007) and breast meat (P < 0.001), and decreased abdominal fat (P < 0.001), but increasing dietary energy level resulted in an adverse effect on carcass traits. We observed an interaction effect on FCR between dietary energy and supplemental Met level (P = 0.033). According to the broken-line models, Met requirements of growing Pekin ducks for optimal FCR at 10.82 and 12.95 MJ/kg of ME were 0.406 and 0.502% when expressed as percentage of diet, or 0.376 and 0.388 when expressed as g/MJ ME of diet, respectively. According to the t-test, Met requirements were different (P < 0.05) when expressed as percentage of diet, but had no difference (P > 0.05) when expressed as g/MJ ME of diet in both dietary ME levels. It indicated that Met requirement was affected by dietary ME level, but the Met/ME ratio was relatively constant in diet of Pekin ducks from 15 to 42 D of age.

Sea-shell-like B31+ and B32: two new axially chiral members of the borospherene family

Since the discovery of the cage-like borospherenes D_2d B₄₀^−/0 and the first axially chiral borospherenes C₃/C₂ B₃₉⁻, a series of fullerene-like boron clusters in different charge states have been reported in theory. Based on extensive global minimum searches and first-principles theory calculations, we present herein two new axially chiral members C₂ B₃₁⁺ (I) and C₂ B₃₂ (VI) to the borospherene family. B₃₁⁺ (I) features two equivalent heptagons on the top and one octagon at the bottom on the cage surface, while B₃₂ (VI) possesses two equivalent heptagons on top and two equivalent heptagons at the bottom. Detailed bonding analyses show that both sea-shell-like B₃₁⁺ (I) and B₃₂ (VI) follow the universal σ + π double delocalization bonding pattern of the borospherene family, with ten delocalized π bonds over a σ skeleton, rendering spherical aromaticity to the systems. Extensive molecular dynamics simulations show that these novel borospherenes are kinetically stable below 1000 K. The IR, Raman, and UV-vis spectra of B₃₁⁺ (I) and B₃₂ (VI) are computationally simulated to facilitate their future experimental characterizations.

Two new axially chiral sea-shell-like boron clusters C₂ B₃₁⁺ (a) and C₂ B₃₂ (b) are presented at first-principles theory level to the borospherene family.

Mechanism of C–P bond formation via Pd-catalyzed decarbonylative phosphorylation of amides: insight into the chemistry of the second coordination sphere

DFT computations establish a detailed reaction mechanism for the first Pd-catalyzed decarbonylative phosphorylation of amides forming C–P bonds, which includes non-covalent interactions as well as proton transfer in the second coordination sphere.

Potent and selective PTP1B inhibition by a platinum(ii) complex: possible implications for a new antitumor strategy

Showing anti-proliferation activity against MCF7 cells better than cisplatin, a platinum(ii) complex, [PtL(DMSO)Cl], was found to potently and selectively inhibit protein tyrosine phosphatase 1B (PTP1B), a putative target for anticancer agents, suggesting a new possible anticancer strategy based on platinum drugs.

[Efficacy comparison of purse-string vs. linear closure of the wound following stoma reversal: systematic review and meta-analysis]

Objective: To compare the efficacy of purse-string skin closure (PSC) and linear skin closure (LSC) in stoma reversal. Methods: Randomized controlled trials (RCT) comparing the use of PSC and LSC during stoma reversal were searched from Embase, PubMed, Web of Science, CNKI net, Wanfang database, VIP Chinese Science and Technology Journal Database. Literature inclusion criteria: (1) randomized controlled trials about comparing PSC and LSC in stoma reversal published publicly; only including English literature; (2) patients undergoing stoma (ileostomy or colostomy) reversal without limitation of age, sex and ethnicity; (3) PSC group receiving the suture of the dermis layer of the skin by purse-string suture, and forming a pore channel in the center of the skin after tightening and knotting, in order to achieve the purpose of secondary healing; the LSC group receiving the suture of the skin with conventional simple interrupted suture; (4) the enrolled literatures needed to include at least one of the following outcome indicators: the primary outcome was the incidence of SSI; the secondary outcome included the operation time, incisional hernia, hospital stay and patient satisfaction. Literature exclusion criteria: (1) duplicate published studies, incomplete studies, reviews, case reports, unpublished literature, retrospective studies, non-RCT. The search time ended on November 15, 2018. The basic information and important outcome indicators of the included articles were extracted. The Cochrane bias risk assessment tool was used to evaluate the quality of the selected literatures. Patient satisfaction was assessed using the following scales: (1) the patient and observer scar assessment scale (POSAS); (2) the body image questionnaire (BIQ); (3) Likert scale; (4) short form 36 (SF-36), version 2; (5) visual analog scale (VAS). Meta-analysis was performed using Review manager 5.3 software provided by the Cochrane Collaboration. Results: A total of 9 randomized controlled trials were included, involving 806 patients with 411 cases in the PSC group and 395 cases in the LSC group. Baseline data such as age, gender, body mass index (BMI), underlying disease, and anesthesia grading were not significantly different between the two groups (all P>0.05). The quality of these nine randomized controlled trials was high. Because the evaluation methods for these studies are not uniform, it is impossible to conduct a meta-analysis of patient satisfaction. However, from the summary results of various studies, the postoperative satisfaction of the purse-string suture group was better than that of the linear suture group. The meta-analysis showed that there was significant difference in postoperative SSI incidence between the PSC group and the LSC group [OR=0.14, 95%CI: 0.08-0.24, P<0.00001], while there were no significant differences in incidence of incisional hernia [OR=0.66, 95%CI: 0.24-1.82, P=0.42], operation time [MD=0.61, 95%CI: -3.17-4.38, P=0.75], and hospital stay [MD=-0.26, 95%CI: -0.82-0.30, P=0.37]. Conclusions: PSC can be used for closure of the wound following stoma reversal. Compared with LSC, PSC can significantly reduce the incidence of SSI, and increase patients' satisfaction.

[Effect of two kinds of materials on the prevention of early erosive enamel wear]

Objective: To investigate the preventive effect of resin infiltration and adhesive on early erosive enamel wear. Methods: Orthodontic reduction premolars collected from Central Laboratory of Nanjing Stomatological Hospital, Medical School of Nanjing University were used to prepare 70 specimens. Forty samples were divided into eight groups (n=5) and treated with different conditions (pH=1.6, 2.4, 3.2 or 4.0 hydrochloric acid solution, etching time was 30 or 60 s), and the conditions for obtaining early erosive enamel samples were selected. Based on this procedure, thirty early erosive enamel samples were made and divided into three groups: control group, resin infiltration group, and adhesive group. And the treatment of 30 days acid abrasion cycle was carried out. Confocal microscopy was used to measure the thickness changes of enamel or material before and after cycle. Results: Early erosive enamel samples was obtained when pH was 4.0 and etching time was 60 s. After 30 days cycle, the wear of enamel was (29.71±6.72) μm in control group, (5.60±2.24) μm in resin infiltration group and (2.89±1.03) μm in adhesive group. In infiltration group and adhesive group, lower enamel was not affected by the cycle, and the material loss ratios of the infiltration resin group and adhesive group were 0.41±0.14 and 0.29±0.13, respectively. The ratio of material loss was not significantly different (P>0.05). But infiltration group lost (12.95±2.22) μm of enamel during the application of the material. Conclusions: Resin infiltration and adhesive have the same short-term protective effect against early erosive enamel wear. Adhesive has less damage to enamel and better effect.

Dual functions of eicosapentaenoic acid-rich microalgae: enrichment of yolk with n-3 polyunsaturated fatty acids and partial replacement for soybean meal in diet of laying hens

Microalgae (Nannochloropsis sp., NS), with high contents of eicosapentaenoic acid (EPA) and crude protein, may be one of the important n-3 polyunsaturated fatty acid (PUFA) sources and potential protein feed ingredient. The purposes of this study were to enrich yolk with n-3 PUFA by dietary EPA-rich NS supplementation and to evaluate whether it is feasible to partly substitute for soybean meal in laying hens diet. A total of 360 37-wk-old healthy Lohmann Brown laying hens, with similar laying rate and body weight, were randomly allotted to 5 groups (6 replicates, 12 birds/replicate) and fed 5 experimental diets (0, 1, 2, 4, and 8% NS) for 4 wk. The hen performance and egg quality (except yolk color) were not affected (P > 0.05) by the NS supplemental diets. Yolk color score was increased as NS supplementation in diets (P < 0.001), and peaked on about the seventh day in all NS supplemental groups. The concentration of total n-3 PUFA was increased (P < 0.001), while total n-6 PUFA and n-6/n-3 ratio were decreased (P < 0.001) in yolk with increasing NS levels in diets. The 8% NS group had highest docosahexaenoic acid (DHA) and total n-3 PUFA levels, reaching 111.6 mg DHA and 148.6 mg total n-3 PUFA per egg. Maximum DHA, total n-3 PUFA, very long-chain (LC-) n-3 PUFA, and LC-PUFA levels were all observed at day 13 of NS supplementation. In conclusion, dietary NS supplementation enriched yolk with n-3 PUFA (especially DHA) and enhanced yolk color score without adverse effects on performance and egg quality, and indicated the practical feasibility of partial replacement for soybean meal in laying hens diet.