Giant Biquadratic Exchange in 2D Magnets and Its Role in Stabilizing Ferromagnetism of NiCl_{2} Monolayers

Two-dimensional (2D) van der Waals (vdW) magnets provide an ideal platform for exploring, on the fundamental side, new microscopic mechanisms and for developing, on the technological side, ultracompact spintronic applications. So far, bilinear spin Hamiltonians have been commonly adopted to investigate the magnetic properties of 2D magnets, neglecting higher order magnetic interactions. However, we here provide quantitative evidence of giant biquadratic exchange interactions in monolayer NiX_{2} (X=Cl, Br and I), by combining first-principles calculations and the newly developed machine learning method for constructing Hamiltonian. Interestingly, we show that the ferromagnetic ground state within NiCl_{2} single layers cannot be explained by means of the bilinear Heisenberg Hamiltonian; rather, the nearest-neighbor biquadratic interaction is found to be crucial. Furthermore, using a three-orbitals Hubbard model, we propose that the giant biquadratic exchange interaction originates from large hopping between unoccupied and occupied orbitals on neighboring magnetic ions. On a general framework, our work suggests biquadratic exchange interactions to be important in 2D magnets with edge-shared octahedra.

Realizing Magnetoelectric Coupling with Hydrogen Intercalation

Materials with a coexistence of magnetic and ferroelectric order (i.e., multiferroics) provide an efficient route for the control of magnetism by electric fields. Unfortunately, a long-sought room temperature multiferroic with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic) orderings is still lacking. Here, we propose that hydrogen intercalation in antiferromagnetic transition-metal oxides is a promising way to realize multiferroics with strong magnetoelectric coupling. Taking brownmillerite SrCoO_{2.5} as an example, we show that hydrogen intercalated SrCoO_{2.5} displays strong ferrimagnetism and large electric polarization in which the hydroxide acts as a new knob to simultaneously control the magnetization and polarization at room temperature. We expect that ion intercalation will become a general way to design magnetoelectric and spintronic functional materials.

[Effects of airway management team in the treatment of severely mass burn patients combined with inhalation injury]

Objective: To explore and analyze the effects of airway management team (AMT) in the treatment of severely mass burn patients combined with inhalation injury. Methods: The clinical data of 58 severely burned patients combined with inhalation injury hospitalized in our unit from January 2012 to August 2014, conforming to the inclusion criteria, were retrospectively analyzed. According to whether airway management was implemented by AMT or not, patients hospitalized from January 2012 to July 2014 were divided into control group (n=27), while patients in Kunshan factory aluminum dust explosion accident hospitalized on 2nd August 2014 were divided into observation group (n=31). Patients in control group received regular airway nursing carried out by nurses on duty, while patients in observation group received specialized airway concentration nursing implemented by AMT. The concrete implementation included overall assessment of patients' airway, elaborate airway care, and controlled management of mechanical ventilation. Arterial blood gas indexes and oxygenation index of patients in the two groups on post injury day (PID) 1, 7, and 14 were compared. Sputum viscosity, ventilator-associated pneumonia (VAP) occurrence rate, and ventilation time of patients in the two groups in post injury week(s) 1, 2, and 3 after admission were monitored and recorded. Survival rates of patients in the two groups were compared. Data were processed with analysis of variance for repeated measurement, t test and Bonferroni correction, chi-square test, and Wilcoxon rank sum test. Results: (1) There were no statistically significant differences in pH value, arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide (PaCO(2)), arterial oxygen saturation (SaO(2)), and oxygenation index of patients in the two groups on PID 1 (t=0.595, -0.166, 1.518, -0.828, 0.458, P>0.05). The pH values of patients in observation group on PID 7 and 14 were 7.327±0.050 and 7.367±0.043, respectively, significantly better than those in control group (7.304±0.021 and 7.390±0.029, respectively, t=-2.385, 2.391, P<0.05). The PaO(2) values of patients in observation group on PID 7 and 14 were (95.1±6.7) and (106.3±7.8) mmHg (1 mmHg=0.133 kPa), respectively, significantly higher than those in control group [(91.6±5.7) and (102.0±8.3) mmHg, respectively, t=-2.109, -2.059, P<0.05]. The PaCO(2) values of patients in observation group on PID 7 and 14 were (41±4) and (40±4) mmHg, respectively, significantly lower than those in control group [(43±5) and (43±4) mmHg, respectively, t=2.220, 2.304, P<0.05]. The SaO(2) values of patients in observation group on PID 7 and 14 were 0.95±0.04 and 0.96±0.04, respectively, significantly higher than those in control group (0.93±0.05 and 0.94±0.05, respectively, t=-2.201, -2.016, P<0.05). The oxygenation indexes of patients in observation group on PID 7 and 14 were (286±18) and (329±20) mmHg, significantly higher than those in control group [(277±14) and (306±58) mmHg, respectively, t=-2.263, -2.022, P<0.05]. (2) Sputum viscosity of patients in observation group in post injury week(s) 1, 2, and 3 were superior to that in control group (Z=-2.096, -2.076, -2.033, P<0.05). (3) VAP occurrence rate of patients in observation group was lower than that in control group, and time of mechanical ventilation of patients in observation group was shorter than that in control group (χ(2)=4.244, t=2.425, P<0.05). (4) Survival rate of patients in observation group was higher than that in control group (χ(2)=4.244, P<0.05). Conclusions: The special intensive care of airway management by AMT can effectively improve the oxygenation status of severely burned patients combined with inhalation injury, alleviate the sputum viscosity, reduce the occurrence of VAP, and shorten the time of mechanical ventilation, thus benefits the treatment of severely mass burn patients combined with inhalation injury.

[Chiral separation by capillary electrochromatography on stationary phase adsorbed with protein]

A method based on the adsorption of bovine serum albumin (BSA) on the strong anion-exchange packing (SAX) was applied to prepare chiral stationary phases for capillary electrochromatography. It was found that the electroosmotic mobility only decreased 26.3% when the BSA was adsorbed. The run-to-run reproducibilities of void time and the migration times of D- and L-tryptophan enantiomers were rather good with the relative standard deviation (RSD) values of 0.90%, 0.87% and 0.96%, respectively, when mobile phase containing 7% (volume fraction) acetonitrile. The merit of this system is that the direction of electroosmotic flow is still from cathode to anode, preferable to separate acidic enantiomers. Four anionic enantiomers, tryptophan, ketoprofen, fenoprofen and warfarin, as well as the neutral enantiomers of benzoin were successfully resolved. In order to reduce the analysis time, n-hexanoic acid was added to the mobile phase as a competitive agent. The effect of acetonitrile volume fraction on the resolution of enantiomers was also investigated.

[Uncharged monolithic capillary column modified with an anionic surfactant in electrochromatography]

A monolithic capillary column was obtained by in-situ co-polymerization of butyl methacrylate with ethylene dimethacrylate. A mode of capillary electrochromatography (CEC) based on the dynamic adsorption of long chain sodium dodecyl sulfate(SDS) on the monolithic stationary phases was developed. Effects of SDS concentration and concentration of acetonitrile in mobile phase on the electroosmotic flow(EOF) of the column and the plate height on the electroosmotic velocity were investigated. Efficiency of monolithic capillary column with higher than 140,000 plates per meter for neutral aromatic compounds were obtained, and the relative standard deviations observed for dead time(t0) and retention times of neutral solutes were about 0.22% and less than 0.56% for ten consecutive runs, respectively.

[The effect of temperature on the enantiomeric resolutions on albumin and beta-cyclodextrin chiral stationary phases]

The effect of column temperature on enantiomeric resolutions of tryptophan, warfarin and ketoprofen was investigated on bovine and human serum albumin (BSA and HSA) stationary phases, which were synthesized with s-triazine as the activator. It was observed that the entropy change made a great contribution to the separation of those enantiomers on albumin chiral stationary phases. The column temperature for the maximal resolution of tryptophan on the BSA stationary phase prepared by this method was about 35 degrees C, which was not 24 degrees C as reported for the BSA stationary phase synthesized with glutaric dialdehyde as the activator. This results may come from the different conformation of the immobilized BSA and HSA due to the different coupling methods used. On the other hand, it was indicated that the resolution of enantiomers on beta-CD chiral stationary phase was mainly contributed from the change of enthalpy, which means the resolution of chiral solutes on albumin and beta-CD stationary phases has different thermodynamic behaviors.

[The preliminary study on the open tubular capillary affinity liquid chromatography]

A novel mode of affinity chromatography based on the open tubular column (OTAC) is presented in this paper. The OTAC column was prepared by coating a layer of Cibacron Blue F3GA onto the inner surface of capillary column with 50 microns inner diameter. The affinity chromatography experiment was performed on a capillary electrophoresis instrument by using its pressure system as driving force. The bovine serum albumin (BSA) and lysozyme (Lys) were successfully separated with step gradient elution. The relative standard deviation (RSD) for 10 consecutive runs for the elution time of lysozyme was less than 0.1%, and those for its peak area and peak height were 4.3% and 3.7% respectively. The good linear relationships of the amount of the injected lysozyme versus its peak area and peak height were observed with correlation coefficients of 0.9946 and 0.9988 respectively in the range from 8.6 ng to 28.7 ng.

[The measurement of shade of colour on 100 cases permanent teeth in Shanghai.]

With the help of a portable Minolta-CR 100 colour difference meter,measurement of upper incisors' surface colour was for the first time domestically carried out in 100 young and middle-aged Shanghai residents,and their mean parameters were also determined.Our method was met he requirements of CIE1931 XYZ surface colour system as well as that of CIE1976 L*a*b* surface colour system.The meter has a quality of high accuracy and the figures thus obtained are concentrated and representative.