[A multicenter clinical study on 1 138 cases of invasive pneumococcal disease in children from 2012 to 2017].

Objective: To explore the clinical features, the serotype distribution and drug resistance of the isolates in patient with invasive pneumococcal disease (IPD). Methods: By retrieving the laboratory information system in 18 children's hospitals from 2012 to 2017, the children with IPD were enrolled. Streptococcus pneumoniae (Spn) must be isolated from the sterile sites (blood, cerebrospinal fluid, hydrothorax and joint effusion etc.). The clinical characteristics, serotype, drug resistance, treatment and prognosis were reviewed and analyzed. According to the telephone follow up results, the patients were divided into death group and recovered group. The index as an independent risk factor of mortality was demonstrated by multivariate logistic regression analysis. Results: There were 1 138 children with IPD, including 684 male and 454 female. The proportion of male to female was 1.5∶1. The age ranged from one day to 16 years. The median age was 1 year 3 month. The majority was under 5 years of age (89.3%, n= 1 016), especially under 2 years of age (61.9%, n=704). In all cases, 88.2% (n=1 004) were community acquired infection. The infections included meningitis (n=446, 39.2%), pneumonia with bacteremia (n=339, 29.8%), and bacteremia without focus (n=232, 20.4%). Underlying diseases were found in 242 cases (21.3%). Co-infections were determined in 62 cases (5.4%) with mycoplasma, 27 cases (2.4%) with adenovirus and 34 cases with influenza virus (3.0%). The penicillin insensitivity (PNSP) rates in meningitis and non-meningitis isolates were 69.5% (276/397) and 35.9% (221/615), respectively. There were 81 strains serotyped, in which 93.8% (76/81) were covered by 13-valent protein-polysaccharide conjugate vaccine (PCV13). In the 965 patients who were followed up by phone call, 156 cases (16.2%) were confirmed dead. The independent risk factors for the death were under 2 years of age (OR=2.143, 95%CI 1.284-3.577, P=0.004), meningitis (OR=3.066, 95%CI 1.852-5.074, P<0.01), underlying disease (OR=4.801, 95%CI 2.953-7.804, P<0.01), septic shock(OR=3.542, 95%CI 1.829-6.859, P<0.01), disseminated intravascular coagulation (DIC) (OR=4.150, 95%CI 1.468-11.733, P=0.007), multiple organ failure (OR=12.693, 95%CI 6.623-24.325, P<0.01) and complications of central nervous system (OR=1.975, 95%CI 1.144-3.410, P=0.015). Conclusions: Most children with IPD were under 5 years of age, having underlying diseases and acquired the infection in community. The independent risk factors for death were under two years old, meningitis, underlying diseases and multiple organ failure. The problem of drug resistance was severe. The universal immunization of PCV13 would be effective to prevent IPD in Chinese children.

Development of interface-dominant bulk Cu/V nanolamellar composites by cross accumulative roll bonding.

Traditional nanostructured metals are inherently comprised of a high density of high-energy interfaces that make this class of materials not stable in extreme conditions. Therefore, high performance bulk nanostructured metals containing stable interfaces are highly desirable for extreme environments applications. Here, we reported an attractive bulk Cu/V nanolamellar composite that was successfully developed by integrating interface engineering and severe plastic deformation techniques. The layered morphology and ordered Cu/V interfaces remained stable with respect to continued rolling (total strain exceeding 12). Most importantly, for layer thickness of 25 nm, this bulk Cu/V nanocomposite simultaneously achieves high strength (hardness of 3.68 GPa) and outstanding thermal stability (up to 700 °C), which are quite difficult to realize simultaneously in traditional nanostructured materials. Such extraordinary property in our Cu/V nanocomposite is achieved via an extreme rolling process that creates extremely high density of stable Cu/V heterophase interfaces and low density of unstable grain boundaries. In addition, high temperature annealing result illustrates that Rayleigh instability is the dominant mechanism driving the onset of thermal instability after exposure to 800 °C.

In vitro investigation of nanohydroxyapatite/poly(L-lactic acid) spindle composites used for bone tissue engineering.

Calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. In this paper, nano-hydroxyapatite/poly(L-lactic acid) (nano-HA/PLLA) spindle composites with good mechanical performance were fabricated by a modified in situ precipitation method. The HA part of composite, distributing homogenously in PLLA matrix, is spindle shape with size of 10-30 nm in diameter and 60-100 nm in length. The molar ratio of Ca/P in the synthesized nano-HA spindles was deduced as 1.52 from the EDS spectra, which is close to the stoichiometric composition of HA (Ca/P & 1.67). The compress strength is up to 150 MPa when the HA content increase to 20 %. The in vitro tests indicate that HA/PLLA bio-composites have good biodegradability and bioactivity when immersed in simulated body fluid solutions. All the results suggested that HA/PLLA nano-biocomposites are appropriate to be applied as bone substitute in bone tissue engineering.

Energetic and kinetic dataset on interaction of the vacancy and self-interstitial atom with the grain boundary in α-iron.

We provide the dataset of the vacancy (interstitial) formation energy, segregation energy, diffusion barrier, vacancy-interstitial annihilation barrier near the grain boundary (GB) in bcc-iron and also the corresponding interactive range. The vacancy-interstitial annihilation mechanisms in the bulk, near the GB and at the GB at across scales were given.

Extraordinary high ductility/strength of the interface designed bulk W-ZrC alloy plate at relatively low temperature.

The refractory tungsten alloys with high ductility/strength/plasticity are highly desirable for a wide range of critical applications. Here we report an interface design strategy that achieves 8.5 mm thick W-0.5 wt. %ZrC alloy plates with a flexural strength of 2.5 GPa and a strain of 3% at room temperature (RT) and ductile-to-brittle transition temperature of about 100 °C. The tensile strength is about 991 MPa at RT and 582 MPa at 500 °C, as well as total elongation is about 1.1% at RT and as large as 41% at 500 °C, respectively. In addition, the W-ZrC alloy plate can sustain 3.3 MJ/m(2) thermal load without any cracks. This processing route offers the special coherent interfaces of grain/phase boundaries (GB/PBs) and the diminishing O impurity at GBs, which significantly strengthens GB/PBs and thereby enhances the ductility/strength/plasticity of W alloy. The design thought can be used in the future to prepare new alloys with higher ductility/strength.

Correlation and the mechanism of lithium ion diffusion with the crystal structure of Li7La3Zr2O12 revealed by an internal friction technique.

The correlation and transport mechanism of lithium ions with the crystal structure of a fast lithium ion conductor Li7La3Zr2O12 are mainly investigated by internal friction (IF) and AC impedance spectroscopy techniques. Compared with the poor conductivity of tetragonal Li7La3Zr2O12, the Al stabilized cubic phase exhibits a good ionic conductivity that can be up to 1.9 × 10(-4) S cm(-1) at room temperature, which can be ascribed to the disordered distribution of lithium ions in the cubic phase. A well-pronounced relaxation IF peak (labeled as peak PC) is observed in the cubic phase while a very weak IF peak (labeled as PT) is observed in the tetragonal phase, further evidencing the difference in lithium ion migration in the two phases. Peak PC can be decomposed into two sub-peaks with the activation energy and the pre-exponential factor of relaxation time being E1 = 0.41 eV and τ01 = 1.2 × 10(-14) s for the lower temperature peak PC1 and E2 = 0.35 eV and τ02 = 1.9 × 10(-15) s for the higher temperature PC2 peak, respectively. Based on the crystalline structure of a cubic garnet-type Li7La3Zr2O12 compound, an atomistic mechanism of lithium ion diffusion via vacancies is suggested, i.e. 48g(96h) ↔ 48g(96h) for peak PC1 and 48g(96h) ↔ 24d for peak PC2, respectively. The weak PT peak in the tetragonal phase is preliminarily interpreted as due to the short jump process among neighboring octahedral sites and vacant tetrahedral sites.

Nano-hydroxyapatite/poly(L-lactic acid) composite synthesized by a modified in situ precipitation: preparation and properties.

Nano-hydroxyapatite/poly(L-lactic acid) (nano-HA/PLLA) composites with uniform HA distribution and good mechanical performance were fabricated by a modified in situ precipitation method, using Ca(OH)(2) and H(3)PO(4) as precursors for the synthesis of HA phase. This method has solved the aggregation problem of the nano-sized particles in the polymer matrix. The X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy were used to characterize the phase composition, chemical interactions and morphology of the composites, while the mechanical properties were determined by compressive measurements. The results show that the rod-like nano-HA particles synthesized by this method were uniformly distributed in the PLLA matrix. The compressive strength and Young's modulus of the composites were greatly enhanced and reached the values of 155 MPa and 3.6 GPa at 20 wt% HA content, respectively, which are much higher than those of the reference samples fabricated by direct mixing of PLLA with nano-HA particles. This supports the potential of these composites for applications in bone tissue engineering and load bearing bone defects repair.

Electrospun submicron bioactive glass fibers for bone tissue scaffold.

Submicron bioactive glass fibers 70S30C (70 mol% SiO(2), 30 mol% CaO) acting as bone tissue scaffolds were fabricated by electrospinning method. The scaffold is a hierarchical pore network that consists of interconnected fibers with macropores and mesopores. The structure, morphological characterization and mechanical properties of the submicron bioactive glass fibers were studied by XRD, EDS, FIIR, SEM, N(2) gas absorption analyses and nanoindentation. The effect of the voltage on the morphology of electrospun bioactive glass fibers was investigated. It was found that decreasing the applied voltage from 19 to 7 kV can facilitate the formation of finer fibers with fewer bead defects. The hardness and Young's modulus of submicron bioactive glass fibers were measured as 0.21 and 5.5 GPa, respectively. Comparing with other bone tissue scaffolds measured by nanoindentation, the elastic modulus of the present scaffold was relatively high and close to the bone.