Regulating Second-Harmonic Generation by van der Waals Interactions in Two-dimensional Lead Halide Perovskite Nanosheets.

The flexible organic amine cations on the interfaces of two-dimensional (2D) hybrid organic-inorganic perovskite nanosheets could form relaxed structures, which would lead to exotic optoelectronic properties but are hard to understand. Here, the unusual interfacial relaxation of nanosheets exfoliated from an orthorhombic 2D lead halide perovskite, [(C6H5CH2NH3)2]PbCl4, is interrogated via ultrafast second-harmonic generation (SHG) spectroscopy. The in-plane SHG intensity anisotropy of these nanosheets is found to decrease with reducing layer thickness. Combined first-principles calculations and Monte Carlo simulations reveal that the induced second-order polarization arises primarily from the (C6H5CH2NH3)+ cations; and these organic amine cations form significantly reorganized conformations with decreasing nanosheet thickness due to weakened van der Waals interactions. Because the orientations of organic components at the interface determine their electric properties and specifically the dipolar susceptibility, the resulting structure leads to striking changes in the SHG properties.

Vertebroplasty versus kyphoplasty in osteoporotic vertebral compression fracture: a meta-analysis of prospective comparative studies.

PURPOSE: The goal of this article is to evaluate the efficacy and the safety of the percutaneous vertebroplasty (PVP) versus percutaneous kyphoplasty (PKP) in dealing with the osteoporotic vertebral compression fracture (OVCF). METHODS: In July 2014, a comprehensive systematic computer-based online search was performed by using the databases of PubMed, EMBASE, Cochrane Library, Web of Science, Wan Fang, and the China Biological Medicine. Only prospective comparative trials (PCT) and randomized controlled trials (RCT) that compared PVP with PKP were included. Trials were screened based on the inclusion and exclusion criteria previously formed. The Cochrane collaboration guidelines were also used to assess the quality of these included studies. The primary data of these studies [volume of the cement, postoperative vertebral height, visual analog scale (VAS) score and Oswestry Disability Index (ODI) score after the surgery, and so on] were carefully abstracted and processed by Revman 5.2.0 software The publication bias of the main results (cement leakage and adjacent-level fracture) were examined by Stata 12.0 (Begg and Egger test). Furthermore, the stability of the main results were also detected by sensitivity and cumulative analyses. RESULTS: Six RCT and 14 PCT studies involving 1,429 patients met our criteria and were included finally. Comparing these two methods, the PKP group took more operation time [SMD = 0.66, 95 % CI (0.28, 1.03), p = 0.0006] with higher anterior vertebral body height [SMD = 1.40, 95 % CI (0.49, 2.32), p = 0.003], greatly reduced Cobb angle in the long run [SMD = -0.61, 95 % CI (-1.04, -0.19), p = 0.005] and had lower risk of cement leakage. However, in VAS scores and ODI scores after the surgery whether for the short-term efficacy (no more than 1 week after the surgery) or long-term efficacy (more than six months), Cobb angle in the short run and new fracture in the adjacent level, no statistically differences were found between the two groups. CONCLUSIONS: Based on current evidence, PVP takes less time in the operation, while it has greater risk of cement leakage, was inferior in reducing Cobb angle in the long term and results in lower anterior vertebral body height after the surgery. For pain relief, which is the main desire of the patients, both procedures provide significant improvement in VAS and ODI pain scores. PVP is still an effective procedure.

The safety and efficacy of minimally invasive discectomy: a meta-analysis of prospective randomised controlled trials.

PURPOSE: The objective of this study was to compare the safety and efficacy of minimally invasive discectomy (MID) with standard discectomy (SD) and determine whether the use of the MID technique could decrease the recurrence of lumbar disc herniation (LDH) after the surgery. METHODS: In February 2014, a comprehensive search was performed in PubMed, EMBASE, Web of Science, Cochrane Library and the Chinese Biological Medicine Database. Only randomised controlled trials (RCT) that compared MID with SD for the surgical management of LDH were included. These trials were carefully picked out following the inclusion and exclusion criteria. Using the Cochrane Collaboration guidelines, two authors independently extracted data and assessed these trials' quality. The age of the patients, size of incision, surgical time, blood loss, visual analogue scale (VAS) score after the surgery, hospital stay, disc herniation recurrence, X-ray exposure and surgical costs in these studies were abstracted and synthesised by a meta-analysis with RevMan 5.2.0 software, and the main results (VAS score after the surgery and disc herniation recurrence) of publication bias were examined by Stata 12.0. RESULTS: Overall, 16 trials involving 2,139 patients meeting our criteria were included and analysed. Comparing MID and SD, the former was more likely to increase disc herniation recurrence [relative risk (RR) = 1.95, 95 % confidence interval (CI) 1.19-3.19, p = 0.008], and it involved a smaller size of incision [mean difference (MD) = -1.91, 95 % CI -3.33 to -0.50, p = 0.008], shorter hospital stay, longer operating time (MD = 11.03, 95 %C I 6.62-15.44, p < 0.00001) and less blood loss (MD = -13.56, 95 % CI -22.26 to -4.87, p = 0.002), while no statistical difference appeared with regard to the age of the patients, VAS score after the surgery, X-ray exposure, hospital stay and surgical costs. CONCLUSIONS: Based on available evidence, MID results in less suffering for patients during the hospital course with a similar clinical efficacy compared to SD. This makes MID a promising procedure for patients with LDH; however, to popularise it greater effort is required to reduce disc herniation recurrence.

Chiral Switchable Low-Dimensional Perovskite Ferroelectrics.

Low-dimensional hybrid organic-inorganic perovskites (HOIPs) possess more localized electronic states and narrower conduction and valence bands to promote self-trapping of excitons and stronger exciton emission; therefore, they are widely used as building blocks for various applications in the fields of optoelectronics, photovoltaics, light-emitting diodes, luminescence, fluorescence, and so forth. Despite the past decades of intensive study, the discovered low-dimensional chiral HOIPs are rare as of the 1D chiral HOIP single crystals reported in 2003, as well as the low-dimensional chiral HOIP ferroelectrics are particularly scarce since the first chiral two-dimensional (2D) and/or one-dimensional (1D) HOIP ferroelectrics reported. Herein, two new low-dimensional HOIPs with the same conformational formula [R-MPA]2CdCl4 (R-MPA+ = (R)-(-)-1-methyl-3-phenylpropylamine) were successfully synthetized by means of regulating the stoichiometric proportion of R-MPA and CdCl2 in two ways of 1:1 (1) and 2:1 (2). By combining single-crystal X-ray diffraction, circular dichroism (CD) spectroscopy, differential scanning calorimetry, temperature-dependent dielectric constant, temperature-dependent second-harmonic generation (SHG) effect, polarization-dependent SHG response, and P-E hysteresis loop, we reveal that 1 is a 1D nonchiral molecular ferroelectric and 2 is the first zero-dimensional (0D) chiral ferroelectric with distinct CD signals; meanwhile, 2 exhibits increased properties of high-Tc, large dielectric constant, SHG isotropy, and ferroelectricity than that of 1. These results not only shed light on the high tunability of the low-dimensional HOIP ferroelectrics but also open up an avenue to explore multifunctional chiral ferroelectrics.

Long-term low-dose tolvaptan treatment in hospitalized male patients aged >90 years with hyponatremia: Report on safety and effectiveness.

The retrospective study aimed at investigating the safety and clinical efficacy of long-term application of tolvaptan in patients >90 years old with hyponatremia. Although tolvaptan has been used to treat hyponatremia, the effect of its long-term use in elderly patients was unknown.Seven patients over 90 with isovolumic or hypervolemic hyponatremia admitted to the PLA Navy General Hospital between October 2011 and October 2013 were enrolled. The patients' serum sodium levels <135 mmol/L persisted for more than 3 months, and oral treatment with tolvaptan lasted for more than 12 months. Tolvaptan dose started from 7.5 mg once daily, with maximum dose no more than 30 mg daily. Clinical and laboratory data of the patients before and after treatment were compared.Serum sodium and chlorine levels increased significantly in the 1st 3 days after treatment (P < .05). All patients' serum sodium levels were above 135 mmol/L 1 month after treatment, and sustained through 1 year after treatment, without extra sodium supplementation. No serious complications were observed.The result indicated a significant improvement in the serum sodium levels and no serious adverse effects after long-term use in very elderly patients.

Differentiation of Human Ligamentum Flavum Stem Cells Toward Nucleus Pulposus-Like Cells Induced by Coculture System and Hypoxia.

STUDY DESIGN: Human ligamentum flavum (LF)-derived stem cells (LFSCs) and nucleus pulposus cells (NPCs) were cocultured under normoxia or hypoxia. OBJECTIVE: To isolate and identify human LFSCs and determine whether they can differentiate into NPCs when cocultured with NPCs under hypoxia. SUMMARY OF BACKGROUND DATA: Mesenchymal stem cell (MSC)-based therapies have been proposed as a biological treatment for intervertebral disc degeneration. MSCs derived from various tissues are leading candidates for cell-based therapies, but such cells have not been reported in LF. METHODS: LF cells were isolated from patient samples and cultured using culture flasks coated with fibronectin, and their identity was confirmed using flow cytometry. The cells were induced to differentiate into osteoblasts, chondrocytes, and adipocytes, and their morphology, immunophenotype, cell proliferation capacity, cell cycle, and expression of stem cell-specific genes were compared with those of bone marrow-MSCs (BM-MSCs) derived from the same patients. NPCs and LFSCs were cocultured in 1-µm-pore-size insert transwell-culture systems under hypoxia (2% O2) or normoxia. CD24 expression was measured by flow cytometry and confocal microscopy assay. On day 14, reverse transcription-polymerase chain reaction was used for comparing the expression of chondrogenic genes (Sox-9, collagen-II, aggrecan) and novel marker genes (KRT19, CA12, FOXF1, HIF-1α) between the 2 groups. RESULTS: LFSCs were obtained using the fibronectin differential-adhesion assay. The morphology of LFSCs was altered, and their immunophenotype, multilineage induction, cell proliferation capacity, cell cycle, and stem cell-specific gene expression were closely related-but not identical-to BM-MSCs, CD24 expression was highly significant in the differentiated LFSCs. RT/Real-time polymerase chain reaction revealed that compared with LFSCs grown under normoxia, hypoxia-treated LFSCs expressed higher levels of Sox-9, collagen-II, aggrecan, KRT19, CA12, and HIF-1α genes except FOXF1. CONCLUSION: Stem cells were identified in human LF, and LFSCs cocultured with NPCs were successfully differentiated into NP-like cells under hypoxia. This potentially provides new cell candidates for cell-based regenerative medicine and tissue engineering. LEVEL OF EVIDENCE: N/A.

[The application of the gene-recombinated cell in the detection of PCBs compounds in environmental samples].

To develop novel and rapid bioassay systems for detection of PCBs in environmental and biological samples, two lines of gene-recombinated cells containing reporter gene, green fluorescent protein (GFP) and luciferase (Luc), were be chosen to detect the PCBs in the water, sediment and biological samples from environment. The result showed that the correlation between RFU of GFP and Luc activity and PCBs standard sample concentration was fine, r was 0.99188 and 0.98239 respectively. Compared with the instrument analysis with GC-ECD, the correlation between RFU of GFP and Luc activity and PCBs concentration in environmental and biological extracts was also fine. The method offered a new way of screening and semi-quantitative bioassay for PCBs compounds in environmental and biological samples.