Ether Naphthotube Host-Guest Complexes and [2]Rotaxanes with Dications

The interactions between ether naphthotube and a series of dication guests in organic solution were investigated. It was found that ether naphthotube formed stable host-guest complexes selectively with these guests in a 1 : 1 stoichiometric ratio with association constants ranging from 102 to 106 M-1, which were confirmed by 1H-NMR spectra and ITC experiments. The host-guest interactions are driven by enthalpy change as the entropic factors are unfavorable. Positive correlations between ΔH and ΔS have been observed in the host-guest complexes. Furthermore, the para-substitution of the guests can significantly affect the binding affinities through a combination of field/inductive and resonance effects by following a linear free energy relationship. Based on the host-guest complexes composed of ether naphthotube and organic cations, two interlocked [2]rotaxanes were prepared by cationization reaction and Huisgen cycloaddition between the cations and the stopper components. The ether naphthotube-based host-guest complexes are useful for creating sophisticated interlocked molecules.

Precise Recognition in Water by an Endo-Functionalized Cavity: Tuning the Complementarity of Binding Sites

Precise binding towards structurally similar substrates is a common feature of biomolecular recognition. However, achieving such selectivity-especially in distinguishing subtle differences in substrates-with synthetic hosts can be quite challenging. Herein, we report a novel design strategy involving the combination of different rigid skeletons to adjust the distance between recognition sites within the cavity, which allows for the highly selective recognition of hydrogen-bonding complementary substrates, such as 4-chromanone. X-ray single-crystal structures and density functional theory calculations confirmed that the distance of endo-functionalized groups within the rigid cavity is crucial for achieving high binding selectivity through hydrogen bonding. The thermodynamic data and molecular dynamics simulations revealed a significant influence of the hydrophobic cavity on the binding affinity. The new receptor possesses both high selectivity and high affinity, which provide valuable insights for the design of customized receptors.

Chiral recognition of neutral guests by chiral naphthotubes with a bis-thiourea endo-functionalized cavity

Developing chiral receptors with an endo-functionalized cavity for chiral recognition is of great significance in the field of molecular recognition. This study presents two pairs of chiral naphthotubes containing a bis-thiourea endo-functionalized cavity. Each chiral naphthotube has two homochiral centers which were fixed adjacent to the thiourea groups, causing the skeleton and thiourea groups to twist enantiomerically through chiral transfer. These chiral naphthotubes are highly effective at enantiomerically recognizing various neutral chiral molecules with an enantioselectivity up to 17.0. Furthermore, the mechanism of the chiral recognition has been revealed to be originated from differences in multiple non-covalent interactions. Various factors, such as the shape of cavities, substituents of guests, flexibility of host and binding modes are demonstrated to contribute to creating differences in the non-covalent interactions. Additionally, the driving force behind enantioselectivity is mainly attributed to enthalpic differences, and enthalpy -entropy compensation has also been observed to influence enantioselectivity.

[Analysis of distribution characteristics of specific immunoglobulin E in 8 092 children with eczema and urticaria in a hospital of pediatric in Tianjin City]

To investigate the common specific immunoglobulin E(sIgE) in children with eczema and urticaria, compare the allergies in children with different diseases, genders and ages, and provide the scientific basis for the prevention, diagnosis and treatment. A retrospective study was conducted to analyze the children who were suspected of eczema and urticaria and tested for serum sIgE in the Tianjin Children's Hospital from December 2019 to August 2021. A total of 8 092 serum samples were tested for ten food allergens and ten inhaled allergens. The method was the enzyme-linked immune capture assay. The allergen epidemiological characteristics were statistically analyzed by Chi square test based on the children's characteristics and factors such as different sexes and ages and by the mass data. The results showed that the positive rate of eczema was 64.42%(5 213/8 092), and the urticaria was 35.58%(2 879/8 092). The positive rate of specific IgE was 66.65%(5 393/8 092), the food allergens was 61.74%(4 996/8 092), and the inhaled allergens was 34.85%(2 820/8 092). The top three positive rates of food allergens were egg 46.65%(3 775/8 092), milk 32.64%(2 641/8 092) and wheat flour 15.08%(1 220/8 092). The top three positive rates of inhaled allergens were house dust 21.40%(1 732/8 092), Alternaria 11.78%(953/8 092) and Dermatophagoides farinae 7.33%(593/8 092). The positivity of food allergens and inhaled allergens was significantly different in different age groups. The positive rates of food allergens in different age groups were 48.92%(947/1 936) in<1 year old, 72.28%(2 680/3 708) in 1-3 years old, 64.58%(919/1 423) in 4-6 years old and 43.90%(450/1 025) in>6 years old. The positive rates of inhaled allergens in different age groups were 17.67%(342/1 936) in<1 year old, 36.35%(1 348/3 708) in 1-3 years old, 46.38%(660/1 423) in 4-6 years old and 45.85%(470/1 025) in>6 years old. The top six positive rates of allergens of eczema were the same with urticaria, which were egg, milk, house dust, wheat flour, Alternaria and Dermatophagoides farinae. The allergens (greater than or equal to grade 4) differed in children with eczema and urticaria. Moreover, there were significant differences in the positive rates of Alternaria, egg, wheat flour, crab and shrimp. In conclusion, this study can reflect the epidemic characteristics of allergens in children with eczema and urticaria to a certain extent. There were significant differences in the positive rates of allergens between different age groups. It is necessary to reasonably avoid the high-risk allergens according to the epidemiological characteristics and clinical symptoms, which provide valuable information for the prevention, diagnosis and treatment of allergic diseases.

[Effect of goal-directed haemodynamic management on the postoperative outcome in elderly patients with fragile cardiac function undergoing abdominal surgery]

Objective: To investigate the effect of goal-directed haemodynamic management based on stroke volume variation (SVV), cardiac index (CI) and mean arterial blood pressure (MAP) on the postoperative outcome in elderly patients with fragile cardiac function undergoing gastrointestinal surgery. Methods: Ninety patients with fragile cardiac function, aged 65-90 years old, ASAⅡ or Ⅲ, NYHA Ⅱor Ⅲ, scheduled for abdominal surgery were enrolled in this study.The patients were randomly assigned to two groups: Experience anesthesia group (group E, n=45) and goal-directed hemodynamic management group (G group, n=45). After anesthesia induction, in group G, the SVV and CI were monitored by Vigileo and according SVV (≤12%), CI (≥2.5 L·min^-1·m^-2) and MAP (maintain the base value of ±20%) to adjust the preloaded infusion fluid and give positive inotropic drugs and positive pressure drugs; in group E, fluid and vasoactive agent were used according to the experience of anesthesiologist.Multi-mode monitoring anesthesia management using BIS, TCI of propofol, low-tidal-volume lung protective ventilation management strategy, body temperature protection, and postoperative multimodal analgesia techniques was performed in the two groups.Values of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin T (cTnT) were recorded before operation, at the end of operation, and postoperative 24 h. The incidence of myocardial infarction/angina, heart failure, arrhythmia and cerebral infarction, renal failure, length of hospitalization, and complications in 30-days after surgery were recorded by telephone follow-up. Results: Crystal, colloid, total liquid of group E were (1 110.20±332.00), (536.65±72.25), (1 677.20±424.44) ml and these of group G were (708.72±240.85), (414.41±74.31), (878.51±199.13) ml, respectively.Compared with group E, the fluid infusion were reduced in group G (t=6.057, 2.701, 9.742, all P<0.05). The lactic acid value of 24 hours after surgery in group G was significantly lower than that in group E [(0.89±0.31) mmol/L vs (1.11±0.43) mmol/L, t=-2.848, P<0.05]. Arterial partial pressure of oxygen at 24 hours after surgery in group G was higher than that in group E [(78.77±6.86) mmHg vs (76.46±10.96) mmHg, t=-1.108, P<0.05]. The length of hospitalization of group G was shorter than that of group E [(12.21±2.20) d vs (13.16±3.84) d, t=-1.341, P<0.05]. The incidence of total complication in hospital and in 30-days after surgery of group G were 10.26% and 5.13%, while these of group E were 29.73% and 24.32%, (χ²=4.545, 4.520, all P<0.05). ΔNT-proBNP₁ (the base value of NT-proBNP's minus the value of NT-proBNP's at the end of the operation) and ΔNT-proBNP₂ (the base value of NT-proBNP's minus the value of NT-proBNP's 24 hours postoperatively) of group G were 12.0(-291.0, 1 517.0) and 0(-6 770.0, 291.0), both higher than these of group E [0(-440.0, 200.0) and -12.0(-7 200, 22.0), (Z=-2.412, -2.163, all P<0.05)]. Conclusion: Goal-directed haemodynamic management based on SVV, CI and MAP could improve the outcome of the elderly patients with fragile heart function undergoing abdominal surgery.

Parity Alternation of Ground-State Pn- and Pn+ (n = 3−15) Phosphorus Clusters

The ground-state structures of neutral, cationic, and anionic phosphorus clusters P(n), P(n)(+), and P(n)(-) (n = 3-15) have been calculated using the B3LYP/6-311+G* density functional method. The P(n)(+) and P(n)(-) (n = 3-15) clusters with odd n were found to be more stable than those with even n, and we provide a satisfactory explanation for such trends based on concepts of energy difference, ionization potential, electron affinity, and incremental binding energy. The result of odd/even alternations is in good accord with the relative intensities of cationic and anionic phosphorus clusters observed in mass spectrometric studies.

Observation of two new N* peaks in J/psi-->ppi-n and ppi+n decays

The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.

Observation of a threshold enhancement in the plambda invariant-mass spectrum

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Observation of the decay psi(2S)-->K0SK0L

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

[Zn8(SiO4)(C8H4O4)6]n: the firstborn of a metallosilicate-organic hybrid material family (C8H4O4 = isophthalate)

[Zn8(SiO4)(C8H4O4)6]n (C8H4O4 = isophthalate), synthesized by hydrothermal reaction, possesses a diamondoid framework structure constructed from hexahedron-like Zn8(SiO4) cores and C8H4O4 linkers and remains stable up to 500 degrees C in air, representing the first member of a new class of metallosilicate-organic hybrid materials.

Separation and identification of perchlorinated polycyclic aromatic hydrocarbons and fullerenes (C60, C70) by coupling high-performance liquid chromatography with ultraviolet absorption spectroscopy and atmospheric pressure chemical ionization mass spectrometry

Simultaneous separation and identification of perchlorinated polycyclic aromatic hydrocarbons (PCPAHs) and fullerenes is of practical interest due to the growth mechanism of fullerenes involved with PCPAHs. Non-aqueous reversed-phase high-performance liquid chromatography (HPLC), with an ODS column and a gradient mobile phase of methanol-ethanol-cyclohexane mixtures, was combined with both rapid-scan ultraviolet spectrometry (UV) and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) for the separation and identification of over 80 PCPAHs as well as fullerenes C60 and C70, that were synthesized in the discharge reaction of chloroform. PCPAH retention was found to depend on the number of aromatic rings and the degree of non-planarity of PCPAH structure. Based on the isotopic pattern of molecular ion or/and quasi-molecular ion peaks in corresponding mass spectra, molecular compositions of the PCPAH products were unambiguously determined. The results obtained from the HPLC-UV-MS analysis not only are helpful for the understanding of the fullerenes formation mechanism, but also contribute to the analytical technique capable of separating and identifying the complicated mixture of PCPAHs and fullerenes.

Separation and identification of perchlorinated polycyclic aromatic hydrocarbons by high-performance liquid chromatography and ultraviolet absorption spectroscopy

High-performance liquid chromatography (HPLC) was coupled with ultraviolet absorption spectroscopy (UV) for the simultaneous separation and identification of a series of perchlorinated polycyclic aromatic hydrocarbons, such as perchlorobenzene (C6Cl6), perchloronaphthalene (C10Cl8), perchlorobiphenyl (C12Cl10), perchloroanthracene (C14Cl10), perchlorophenanthrene (C14C10), perchloroacenaphthylene (C12Cl8), perchloropyrene (C16Cl10) and perchlorofluoranthene (C16Cl10). HPLC was performed on an ODS column using methanol-hexane (80:20) as mobile phase at a flow-rate of 1.0 ml/min. UV absorption spectra of the elutes were detected in the region of 210-350 nm.