A numerical study on the charge transport in TPD/Alq3-based organic light emitting diodes

We report our simulation study on the charge transport characteristic of the multi-layer structure for organic light emitting diodes (OLEDs). We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes. The material of the HTL is TPD (N,N'-Bis (3-methylphenyl)-N,N'-bis(phenyl) benzidine), and the ETL includes Alq3 (Tris (8-hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on/off period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, our numerical simulation revealed that the insertion of the EML affects the photonic characteristics in bilayer structure and also the efficiency due to the difference in the internal barrier height.

The impact of group B Streptococcus prophylaxis on early onset neonatal infections

OBJECTIVE

To determine if changes have occurred in the causative pathogens and/or antibiotic susceptibility profiles in early onset neonatal infections since initiation of group B Streptococcus (GBS) prophylaxis and to determine risk factors for ampicillin/penicillin resistant microorganisms.

STUDY DESIGN

Data on 220 infants with positive blood, urine, or cerebrospinal fluid cultures for bacteria or fungi at ≤seven days of age from 1990-2007 were examined and divided into three epochs, based on intrapartum antibiotic prophylactic (IAP) practices. Pathogens and antibiotic resistance were compared among epochs.

RESULTS

A significant decrease in the incidence of GBS infections occurred over time, with no change in the incidence of other pathogens or the emergence of antibiotic resistance, including the very low-birthweight population. In regression analysis, ampicillin resistance was associated with male gender (OR 3.096).

CONCLUSIONS

No emergence of antibiotic resistant pathogens was found following IAP use. Changing microorganisms and increasing antibiotic resistance found in prior studies are likely multifactorial. Further study is needed to continue to reduce the rates of common early onset pathogens.

Impact of internal spermatic artery preservation during laparoscopic varicocelectomy on recurrence and the catch-up growth rate in adolescents

OBJECTIVE

To investigate the effectiveness of laparoscopic varicocelectomy (LV) in adolescents with varicocele and analyze the impact of internal spermatic artery (ISA) preservation on surgical outcomes.

MATERIALS AND METHODS

Data on 92 adolescents with left varicocele who underwent LV between December 1998 and January 2011 were retrospectively analyzed. The mean age of the patients was 13.2 ± 2.1 years. Age, grade of disease, number of ligation veins, recurrence rates, and catch-up growth were analyzed in patients who underwent ISA preservation and ligation. The median duration of the follow-up was 21 months.

RESULTS

ISA preservation was performed on 50 patients (54%). There were no significant inter-group differences in terms of age, varicocele grade, number of ligation veins, and catch-up growth (93% vs. 90%). The patients who received artery preservation demonstrated a higher recurrence rate (22%) than those who received artery ligation (5%; p = 0.032). Among 13 patients who had persistent or recurrent varicocele, nine were treated with embolization and one was treated with magnification-assisted subinguinal varicocelectomy. None of these 10 patients demonstrated recurrence or testicular atrophy.

CONCLUSIONS

LV with ISA ligation can reduce the recurrence rate and results in the same catch-up growth rate in comparison with LV with ISA preservation.

Association between BMP-2 and COL6A1 gene polymorphisms with susceptibility to ossification of the posterior longitudinal ligament of the cervical spine in Korean patients and family members

COL6A1 and BMP-2 genes have been implicated in ossification of the posterior longitudinal ligament (OPLL) susceptibility in Japanese and Chinese Han populations. However, no study has yet investigated the DNA of unaffected family members of patients with OPLL. This study investigated differences in genetic polymorphisms of BMP-2 and COL6A1 between Korean patients with OPLL and their family members (with and without OPLL). A total of 321 subjects (110 patients with OPLL and 211 family members) were enrolled in the study. Associations between two single nucleotide polymorphisms (SNPs) of the BMP-2 gene (Ser37Ala and Ser87Ser) and two SNPs of COL6A1 [promoter (-572) and intron 33 (+20)] with susceptibility to OPLL of the cervical spine were investigated between the two groups (OPLL+ and OPLL-). Of the 321 subjects, 162 had cervical OPLL (50.4%; 110 patients, 52 family members). There was a familial tendency of OPLL in 34 of the 110 families (30.9%). Allele and haplotype frequencies of the four SNPs in the BMP-2 and COL6A1 genes did not differ significantly between the OPLL+ and OPLL- groups, even when excluding participants over 50 years of age. This is the first report identifying SNPs of COL6A1 and BMP-2 in Korean patients and family members with OPLL. Although allele and haplotype frequencies were similar with those of a previous study in Japanese and Chinese patients, unaffected family members also showed similar rates of these SNPs in the present study. These results suggest that these SNPs may not directly influence the expression of OPLL.

Statistical mechanics model for the dynamics of collective epigenetic histone modification

Epigenetic histone modifications play an important role in the maintenance of different cell phenotypes. The exact molecular mechanism for inheritance of the modification patterns over cell generations remains elusive. We construct a Potts-type model based on experimentally observed nearest-neighbor enzyme lateral interactions and nucleosome covalent modification state biased enzyme recruitment. The model can lead to effective nonlocal interactions among nucleosomes suggested in previous theoretical studies, and epigenetic memory is robustly inheritable against stochastic cellular processes.

An alginate-like exopolysaccharide biosynthesis gene cluster involved in biofilm aerial structure formation by Pseudomonas alkylphenolia

Pseudomonas alkylphenolia is known to form different types of multicellular structures depending on the environmental stimuli. Aerial structures formed during vapor p-cresol utilization are unique. Transposon mutants that showed a smooth colony phenotype failed to form a differentiated biofilm, including aerial structures and pellicles, and showed deficient surface spreading motility. The transposon insertion sites were located to a gene cluster designated epm (extracellular polymer matrix), which comprises 11 ORFs in the same transcriptional orientation. The putative proteins encoded by the genes in the epm cluster showed amino acid sequence homology to those found in the alginate biosynthesis gene clusters, e.g., in Pseudomonas aeruginosa at similarity levels of 32.3-86.4 %. This overall resemblance indicated that the epm gene cluster encodes proteins that mediate the synthesis of an exopolysaccharide composed of uronic acid(s) similar to alginate. Our preliminary results suggested that the epm-derived polymer is a substituted polymannuronic acid. Gene clusters homologous to the epm gene cluster are found in the genomes of a few species of the genera Pseudomonas, Alcanivorax, and Marinobacter. A mutational analysis showed that the epmJ and epmG genes encoding putative exopolysaccharide-modifying enzymes are required to form multicellular structures. An analysis of the activity of the promoter P epmD using a transcriptional fusion to the green fluorescence protein gene showed that the epm genes are strongly expressed at the tips of the specialized aerial structures. Our results suggested that the epm gene cluster is involved in the formation of a scaffold polysaccharide that is required to form multicellular structures in P. alkylphenolia.

Numerical study on exciton transport and light emission for organic light emitting diodes with an emission layer

This paper reports the results of a numerical study on carrier injection and exciton transport in an organic light emitting diode (OLED) structure based on tris (8-hydroxyquinolinato) aluminum (Alq3). Because charge accumulation at the interfaces between the emission layer (EML) and transport layer are believed to increase the recombination rate, which also increases the exciton density, a numerical study was performed on the effect of inserting an EML in the bilayer structure. In the first case considered, the lowest unoccupied molecular orbital (LUMO) of the EML was aligned with the LUMO of the hole transport layer (HTL), whereas the highest occupied molecular orbital (HOMO) of the EML was aligned with the HOMO of the electron transport layer (ETL). In the second case, the LUMO of the EML was aligned with the LUMO of the ETL and the HOMO of the EML was aligned with the HOMO of the HTL. In case of a charge-blocking device, most of the recombination appeared to occur at both edges of the EML because the electric field exhibited a peak in these areas. On the other hand, in the case of the charge-confining device, the electric field was confined at the interface between the EML and ETL. This paper also discussed the effect of the insertion of a doping layer as transport layer.

Self-organizing properties of triethylsilylethynyl-anthradithiophene on monolayer graphene electrodes in solution-processed transistors

Graphene has shown great potential as an electrode material for organic electronic devices such as organic field-effect transistors (FETs) because of its high conductivity, thinness, and good compatibility with organic semiconductor materials. To achieve high performance in graphene-based organic FETs, favorable molecular orientation and good crystallinity of organic semiconductors on graphene are desired. This strongly depends on the surface properties of graphene. Here, we investigate the effects of polymer residues that remain on graphene source/drain electrodes after the transfer/patterning processes on the self-organizing properties and field-effect characteristics of the overlying solution-processed triethylsilylethynyl-anthradithiophene (TES-ADT). A solvent-assisted polymer residue removal process was introduced to effectively remove residues or impurities on the graphene surface. Unlike vacuum-deposited small molecules, TES-ADT displayed a standing-up molecular assembly, which facilitates lateral charge transport, on both the residue-removed clean graphene and as-transferred graphene with polymer residues. However, TES-ADT films grown on the cleaned graphene showed a higher crystallinity and larger grain size than those on the as-transferred graphene. The resulting TES-ADT FETs using cleaned graphene source/drain electrodes therefore exhibited a superior device performance compared to devices using as-transferred graphene electrodes, with mobilities as high as 1.38 cm(2) V(-1) s(-1).

Diagnostic performance of 18F-FDG PET/CT, ultrasonography and MRI. Detection of axillary lymph node metastasis in breast cancer patients

The aim of this study was to evaluate the diagnostic abilities of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography(PET/CT) compared with those of ultrasonography and magnetic resonance imaging (MRI) for axillary lymph node staging in breast cancer patients.

PATIENTS, METHODS

Preoperative 18F-FDG PET/non-contrast CT, ultrasonography and MRI were performed in 215 women with breast cancer. Axillary lymph node dissection was performed in all patients and the diagnostic performance of each modality was evaluated using histopathologic assessments as the reference standard. ROC curves were compared to evaluate the diagnostic ability of several imaging modalities (i. e., ultrasonography, MRI and 18F-FDG PET/CT).

RESULTS

In total, 132 patients (61.4%) had axillary lymph node metastasis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for the detection of axillary lymph node metastasis were 72.3%, 77.3%, 66.7%, 81.6%, 75.3% for ultrasonography, 67.5%, 78.0%, 65.9%, 79.2%, 74.0% for MRI, and 62.7%, 88.6%, 77.6%, 79.1%, 78.6% for 18F-FDG PET/CT, respectively. There was no significant difference in diagnostic ability among the imaging modalities (i.e., ultrasonography, MRI and 18F-FDG PET/CT). The diagnostic ability of 18F-FDG PET/CT was significantly improved by combination with MRI (p = 0.0002) or ultrasonography (p < 0.0001). The combination of 18F-FDG PET/CT with ultrasonography had a similar diagnostic ability to that of all three modalities combined (18F-FDG PET/CT+ultrasonography+MRI, p = 0.05).

CONCLUSION

The diagnostic performance of 18F-FDG PET/CT for detection of axillary node metastasis was not significantly different from that of ultrasonography or MRI in breast cancer patients. Combining 18F-FDG PET/CT with ultrasonography or MRI could improve the diagnostic performance compared to 18F-FDG PET/CT alone.

Brain MRI measurements at a term-equivalent age and their relationship to neurodevelopmental outcomes

BACKGROUND AND PURPOSE

An increased prevalence of disabilities is being observed as more preterm infants survive. This study was conducted to evaluate correlations between brain MR imaging measurements taken at a term-equivalent age and neurodevelopmental outcome at 2 years' corrected age among very low-birth-weight infants.

MATERIALS AND METHODS

Of the various brain MR imaging measurements obtained at term-equivalent ages, reproducible measurements of the transcerebellar diameter and anteroposterior length of the corpus callosum on sagittal images were compared with neurodevelopmental outcomes evaluated by the Bayley Scales of Infant Development (II) at 2 years' corrected age (mean ± standard deviation, 16.1 ± 6.4 months of age).

RESULTS

Ninety infants were enrolled. The mean gestational age at birth was 27 weeks and the mean birth weight was 805.5 g. A short corpus callosal length was associated with a Mental Developmental Index <70 (P = .047) and high-risk or diagnosed cerebral palsy (P = .049). A small transcerebellar diameter was associated with a Psychomotor Developmental Index <70 (P = .003), Mental Developmental Index <70 (P = .004), and major neurologic disability (P = .006).

CONCLUSIONS

A small transcerebellar diameter and short corpus callosal length on brain MR imaging at a term-equivalent age are related to adverse neurodevelopmental outcomes at a corrected age of 2 years and could be a useful adjunctive tool for counseling parents about future developmental outcomes.

Flexible thermochromic window based on hybridized VO2/graphene

Large-scale integration of vanadium dioxide (VO2) on mechanically flexible substrates is critical to the realization of flexible smart window films that can respond to environmental temperatures to modulate light transmittance. Until now, the formation of highly crystalline and stoichiometric VO2 on flexible substrate has not been demonstrated due to the high-temperature condition for VO2 growth. Here, we demonstrate a VO2-based thermochromic film with unprecedented mechanical flexibility by employing graphene as a versatile platform for VO2. The graphene effectively functions as an atomically thin, flexible, yet robust support which enables the formation of stoichiometric VO2 crystals with temperature-driven phase transition characteristics. The graphene-supported VO2 was capable of being transferred to a plastic substrate, forming a new type of flexible thermochromic film. The flexible VO2 films were then integrated into the mock-up house, exhibiting its efficient operation to reduce the in-house temperature under infrared irradiation. These results provide important progress for the fabrication of flexible thermochromic films for energy-saving windows.

RAF kinase inhibitor-independent constitutive activation of Yes-associated protein 1 promotes tumor progression in thyroid cancer

The transcription coactivator Yes-associated protein 1 (YAP1) is regulated by the Hippo tumor suppressor pathway. However, the role of YAP1 in thyroid cancer, which is frequently associated with the BRAF^V600E mutation, remains unknown. This study aimed to investigate the role of YAP1 in thyroid cancer. YAP1 was overexpressed in papillary (PTC) and anaplastic thyroid cancer, and nuclear YAP1 was more frequently detected in BRAF^V600E (+) PTC. In the thyroid cancer cell lines TPC-1 and HTH7, which do not have the BRAF^V600E mutation, YAP1 was cytosolic and inactive at high cell densities. In contrast, YAP1 was retained in the nucleus and its target genes were expressed in the thyroid cancer cells 8505C and K1, which harbor the BRAF^V600E mutation, regardless of cell density. Furthermore, the nuclear activation of YAP1 in 8505C was not inhibited by RAF or MEK inhibitor. In vitro experiments, YAP1 silencing or overexpression affected migratory capacities of 8505C and TPC-1 cells. YAP1 knockdown resulted in marked decrease of tumor volume, invasion and distant metastasis in orthotopic tumor xenograft mouse models using the 8505C thyroid cancer cell line. Taken together, YAP1 is involved in the tumor progression of thyroid cancer and YAP1-mediated effects might not be affected by the currently used RAF kinase inhibitors.

Electronic instability in a zero-gap semiconductor: the charge-density wave in (TaSe4)2I

We report a comprehensive study of the paradigmatic quasi-1D compound (TaSe(4))(2)I performed by means of angle-resolved photoemission spectroscopy (ARPES) and first-principles electronic structure calculations. We find it to be a zero-gap semiconductor in the nondistorted structure, with non-negligible interchain coupling. Theory and experiment support a Peierls-like scenario for the charge-density wave formation below T(CDW)=263  K, where the incommensurability is a direct consequence of the finite interchain coupling. The formation of small polarons, strongly suggested by the ARPES data, explains the puzzling semiconductor-to-semiconductor transition observed in transport at T(CDW).

Tunable polaronic conduction in anatase TiO2

Oxygen vacancies created in anatase TiO(2) by UV photons (80-130 eV) provide an effective electron-doping mechanism and induce a hitherto unobserved dispersive metallic state. Angle resolved photoemission reveals that the quasiparticles are large polarons. These results indicate that anatase can be tuned from an insulator to a polaron gas to a weakly correlated metal as a function of doping and clarify the nature of conductivity in this material.

Enhanced optical response of hybridized VO₂/graphene films

Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ∼56 °C.

First result from the Alpha Magnetic Spectrometer on the International Space Station: precision measurement of the positron fraction in primary cosmic rays of 0.5-350 GeV

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250  GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

Dietary (periphyton) and aqueous Zn bioaccumulation dynamics in the mayfly Centroptilum triangulifer

Diet is often the predominant route of trace metal exposure in aquatic insects. In freshwater ecosystems, periphyton serves as a primary source of food to many aquatic insects and is a major sink for trace metals. We investigated the bioconcentration of the essential metal Zn by periphyton using (65)Zn as a radiotracer. At relatively low dissolved concentrations (2-20 μg L(-1)), non steady state Zn bioconcentration by periphyton averaged 6,099 ± 2,430-fold, with much of the variability determined by loading regime (number of renewals and duration of exposures). Labeled periphyton was used as a food source for dietary accumulation studies with the mayfly Centroptilum triangulifer. After 29 days, larvae concentrated Zn 19-, 16- and 17-fold relative to dietary Zn concentrations of 8.1, 43.2 and 82.3 μg g(-1) (dry weight), respectively. Adults from that same cohort only concentrated Zn 8-, 3- and 3- fold relative to those same dietary concentrations, revealing that mayflies lose significant Zn prior to reaching adulthood. Anecdotal evidence suggests that this loss occurs prior to emergence to the subimago, as negligible Zn was found in the subimago to imago exuvium. Across a range of adult tissue concentrations, maternal transfer consistently averaged 26.7 %. Uptake (k(u), 0.26 L g(-1 )d(-1)) and efflux rate constants (k(e), 0.001-0.007 d(-1)) were measured and assimilation efficiencies from dietary Zn concentrations of 4.9 and 59.7 μg Zn g(-1) were estimated to be 88 ± 4 % and 64 ± 15 %, respectively. Both life cycle and biodynamic modeling approaches point towards diet being the primary route of Zn bioaccumulation in this mayfly.

Evaluation of BTA1 and BTA5 QTL Regions for Growth and Carcass Traits in American and Korean Cattle

Previously identified QTL regions on BTA1 and BTA5 were investigated to validate the QTL regions and to identify candidate genes for growth and carcass traits in commercial cattle populations from the USA and Korea. Initially, a total of 8 polymorphic microsatellite (MS) markers in the BTA1 and 5 QTL regions were used for Chi-square tests to compare the frequencies of individual alleles between high and low phenotypic groups for the US (Michigan Cattleman’s Association/Michigan State University; MCA/MSU) cattle. For a subsequent study, 24 candidate genes containing missense mutations and located within the QTL regions based on bovine genome sequence data were analyzed for genotyping in the two commercial cattle populations. Re-sequencing analyses confirmed 18 public missense SNPs and identified 9 new SNPs. Seventeen of these SNPs were used for genotyping of the MCA/MSU cattle (n = 98) and Korean native cattle (n = 323). On BTA1, UPK1B, HRG, and MAGEF1 polymorphisms residing between BM1312 and BMS4048 were significantly associated with growth and carcass traits in one or both of the MCA/MSU and Korean populations. On BTA5, ABCD2, IL22 and SNRPF polymorphisms residing between BL4 and BR2936 were associated with marbling and backfat traits in one or both of the MCA/MSU and Korean cattle populations. These results suggested that BTA 1 and 5 QTL regions may be segregating in both Korean Hanwoo and USA commercial cattle populations and DNA markers tested in this study may contribute to the identification of positional candidate genes for marker-assisted selection programs.

Effective plasmid DNA and small interfering RNA delivery to diseased human brain microvascular endothelial cells

Expression of exogenous DNA or small interfering RNA (siRNA) in vitro is significantly affected by the particular delivery system utilized. In this study, we evaluated the transfection efficiency of plasmid DNA and siRNA into human brain microvascular endothelial cells (HBMEC) and meningioma cells, which constitute the blood-cerebrospinal fluid barrier, a target of meningitis-causing pathogens. Chemical transfection methods and various lipofection reagents including Lipofectamin™, FuGene™, or jetPRIME®, as well as physical transfection methods and electroporation techniques were applied. To monitor the transfection efficiencies, HBMEC and meningioma cells were transfected with the reporter plasmid pTagGFP2-actin vector, and efficiency of transfection was estimated by fluorescence microscopy and flow cytometry. We established protocols based on electroporation using Cell Line Nucleofector® Kit V with the Amaxa® Nucleofector® II system from Lonza and the Neon® Transfection system from Invitrogen resulting in up to 41 and 82% green fluorescent protein-positive HBMEC, respectively. Optimal transfection solutions, pulse programs and length were evaluated. We furthermore demonstrated that lipofection is an efficient method to transfect meningioma cells with a transfection efficiency of about 81%. Finally, we applied the successful electroporation protocols to deliver synthetic siRNA to HBMEC and analyzed the role of the actin-binding protein cortactin in Neisseria meningitidis pathogenesis.

A novel nortriterpene fromHedera rhombea

A new nortriterpene, rhombenone (1) was isolated from the leaves ofHedera rhombea Bean (Araliaceae). The structure of this compound was established as 27-demethyl-20(S)-dammar-23-ene-6alpha,20-diol-3,25-dione on the basis of spectral analysis including HMQC and HMBC techniques. Rhombenone (1) was the first 27-demethyl nortriterpene of dammarance type isolated from natural sources.

The spatial genetic differentiation of the legume pod borer, Maruca vitrata F. (Lepidoptera: Crambidae) populations in West Africa

The legume pod borer, Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa. The application of population genetic tools is important in the management of insect pests but such data on M. vitrata is lacking. We applied a set of six microsatellite markers to assess the population structure of M. vitrata collected at five sites from Burkina Faso, Niger and Nigeria. Observed polymorphisms ranged from one (marker 3393) to eight (marker 32008) alleles per locus. Observed and expected heterozygosities ranged from 0.0 to 0.8 and 0.0 to 0.6, respectively. Three of the loci in samples from Nigeria and Burkina Faso deviated significantly from Hardy-Weinberg Equilibrium (HWE), whereas no loci deviated significantly in samples from Niger. Analysis of molecular variance (AMOVA) indicated that 67.3% level of the genetic variation was within individuals compared to 17.3% among populations. A global estimate of F ST=0.1 (ENA corrected F ST=0.1) was significant (P⩽0.05) and corroborated by pairwise F ST values that were significant among all possible comparisons. A significant correlation was predicted between genetic divergence and geographic distance between subpopulations (R2=0.6, P=0.04), and cluster analysis by the program STRUCTURE predicted that co-ancestry of genotypes were indicative of three distinct populations. The spatial genetic variance among M. vitrata in West Africa may be due to limited gene flow, south-north seasonal movement pattern or other reproductive barriers. This information is important for the cultural, chemical and biological control strategies for managing M. vitrata.

What is the importance of "halo" phenomenon around bone cement following vertebral augmentation for osteoporotic compression fracture?

We investigated the importance, risk factors, and clinical course of the radiolucent "halo" phenomenon around bone cement following vertebral augmentation for osteoporotic compression fracture. Preoperative osteonecrosis and a lump cement pattern were the most important risk factors for the peri-cement halo phenomenon, and it was associated with vertebral recollapse.

INTRODUCTION

We observed a newly developed radiolucent area around the bone cement following vertebral augmentation for osteoporotic compression fractures. Here, we describe the importance of the peri-cement halo phenomenon, as well as any associated risk factors and long-term sequelae.

METHODS

In total, 175 patients (202 treated vertebrae) were enrolled in this study. The treated vertebrae were subdivided into two groups: Group A (with halo, n = 32) and Group B (without halo, n = 170), and the groups were compared with respect to multiple preoperative (age, sex, BMD, preoperative osteonecrosis) and perioperative factors (operative approach: vertebroplasty or kyphoplasty; cement distribution pattern; cement leakage; cement volume), and postoperative results (VAS score, recollapse). Logistic regression analysis was used to evaluate the relationship between the incidence of the peri-cement halo and all of the parameters described above.

RESULTS

Rates of osteonecrosis were also significantly higher in Group A than in Group B (62.5% vs. 31.2%, p < 0.05), and kyphoplasty (KP) was performed more frequently in Group A (43.8% vs. 17.6%, p < 0.05). Lump cement (93.8% vs. 30.6%, p < 0.05) and recollapse (78.1% vs. 24.7%, p < 0.05) were also more common among individuals in Group A. Logistic regression analysis also showed that preoperative osteonecrosis (OR = 3.679; 95% CI = 1.677-8.073; p = 0.001), KP (OR = 3.630; 95% CI = 1.628-8.095; p = 0.002), lump pattern (OR = 13.870; 95% CI = 2.907-66.188; p = 0.001), and vertebral recollapse (OR = 5.356; 95% CI = 1.897-15.122; p = 0.002) were significantly associated with peri-cement halo.

CONCLUSIONS

The peri-cement halo was found to be associated with vertebral recollapse, this sign likely represents a poor prognostic factor after vertebral augmentation for osteoporotic compression fractures.

Connecting dopant bond type with electronic structure in N-doped graphene

Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.