bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon‐doped p‐type (0001) plane AlGaN (Al = 6–55%) with high hole density
Authors: Kawanishi Hideo , Tomizawa Tatsuya 
Published: January 2012

AbstractIn this paper, promising experimental results for the p‐type electrical properties of carbon‐doped (C‐doped) AlGaN are discussed. P‐type conductivity was experimentally achieved in C‐doped (0001) plane AlGaN layers with from a small amount to 55% solid Al composition, but not in (0001) plane GaN. The maximum free hole density (determined by van der Pauw geometry‐Hall effect measurement) achieved for an AlGaN layer with 10% solid Al composition was p = 3.2 × 1018 cm−3. The maximum net ionized acceptor densities (NIAD), $N_{{\rm A}}^{- } - N_{{\rm D}}^{ + } $, which were determined by capacitance–voltage measurement, for AlGaN with 6, 10, 27, and 55% solid Al compositions, were all in the range of (6–7) × 1018 cm−3. Moreover, the electrical activity of the carbon acceptors was estimated to be 55–71% from the NIAD and secondary‐ion microprobe mass spectrometry analysis data on the carbon concentration. A p–n junction was also fabricated using the C‐doped p‐type AlGaN.
Hydrogel Nanoparticles with Covalently Linked Coomassie Blue for Brain Tumor Delineation Visible to the Surgeon
Authors: Nie Guochao , Hah Hoe Jin , Kim Gwangseong , Lee Yong‐Eun Koo , Qin Ming , Ratani Tanvi S. , Fotiadis Panagiotis , Miller Amber , Kochi Akiko , Gao Di , Chen Thomas , Orringer Daniel A. , Sagher Oren , Philbert Martin A. , Kopelman Raoul 
Published: January 2012

AbstractDelineation of tumor margins is a critical and challenging objective during brain cancer surgery. A tumor‐targeting deep‐blue nanoparticle‐based visible contrast agent is described, which, for the first time, offers in vivo tumor‐specific visible color staining. This technology thus enables color‐guided tumor resection in real time, with no need for extra equipment or special lighting conditions. The visual contrast agent consists of polyacrylamide nanoparticles covalently linked to Coomassie Blue molecules (for nonleachable blue color contrast), which are surface‐conjugated with polyethylene glycol and F3 peptides for efficient in vivo circulation and tumor targeting, respectively.
Engineered Redox‐Responsive PEG Detachment Mechanism in PEGylated Nano‐Graphene Oxide for Intracellular Drug Delivery
Authors: Wen Huiyun , Dong Chunyan , Dong Haiqing , Shen Aijun , Xia Wenjuan , Cai Xiaojun , Song Yanyan , Li Xuequan , Li Yongyong , Shi Donglu 
Published: January 2012

AbstractIn biomedical applications, polyethylene glycol (PEG) functionalization has been a major approach to modify nanocarriers such as nano‐graphene oxide for particular biological requirements. However, incorporation of a PEG shell poses a significant diffusion barrier that adversely affects the release of the loaded drugs. This study addresses this critical issue by employing a redox‐responsive PEG detachment mechanism. A PEGylated nano‐graphene oxide (NGO‐SS‐mPEG) with redox‐responsive detachable PEG shell is developed that can rapidly release an encapsulated payload at tumor‐relevant glutathione (GSH) levels. The PEG shell grafted onto NGO sheets gives the nanocomposite high physiological solubility and stability in circulation. It can selectively detach from NGO upon intracellular GSH stimulation. The surface‐engineered structures are shown to accelerate the release of doxorubicin hydrochloride (DXR) from NGO‐SS‐mPEG 1.55 times faster than in the absence of GSH. Confocal microscopy shows clear evidence of NGO‐SS‐mPEG endocytosis in HeLa cells, mainly accumulated in cytoplasm. Furthermore, upon internalization of DXR‐loaded NGO with a disulfide‐linked PEG shell into HeLa cells, DXR is effectively released in the presence of an elevated GSH reducing environment, as observed in confocal microscopy and flow cytometric experiments. Importantly, inhibition of cell proliferation is directly correlated with increased intracellular GSH concentrations due to rapid DXR release.
Tuning Ratios, Densities, and Supramolecular Spacing in Bifunctional DNA‐Modified Gold Nanoparticles
Authors: Díaz Julián A. , Grewer David M. , Gibbs‐Davis Julianne M. 
Published: January 2012

AbstractMethods for combining multiple functions into well‐defined nanomaterials are still lacking, despite their need in nanomedicine and within the broader field of nanotechnology. Here several strategies for controlling the amount and the ratio of combinations of labeled DNA on 13‐nm gold nanoparticles using self‐assembly of thiolated DNA and/or DNA‐directed assembly are explored. It is found that the self‐assembly of mixtures of fluorescently labeled DNA can lead to a higher amount of labeled DNA per particle; however, the ratio of fluorophores on the nanoparticles differs greatly from that in the self‐assembly solution. In contrast, when fluorescently labeled DNA are hybridized to DNA‐modified gold nanoparticles, the fluorophore ratio on the nanoparticles is much closer to their ratio in solution. The use of bifunctional DNA‐doublers in self‐assembly and DNA‐directed assembly is also explored to increase the complexity of these materials and control their composition. Finally, tuning the distance between the labels from 2.9 to 5.4 nm was achieved using different hybridized DNA clamp complexes. Fluorescent results suggest that assembling these clamps on nanoparticle surfaces may be possible, although the resulting label spacing could not be quantified.
Thermoplastic starch modified with polyurethane microparticles: Effects of hydrophilicity of polyurethane prepolymer
Authors: Chen Xiaoxia , Zhang Yu , Zhang Pingping , Fan Bingbing , Wu Qiangxian 
Published: January 2012

AbstractIt is important to chemically modify starch in an effective way. In this study, a series of polyurethane prepolymers (PUP) using 2,2‐dimethylol propionic acid (DMPA) as hydrophilic chain extender was synthesized and then used to modify starch by intensive mixing to obtain modified thermoplastic starch (TPS). The structure and properties of the modified TPS were investigated. The results showed that the elongation at break of the modified TPS increased from 5.4 to 9.8% with the content of PUP in modified TPS increasing from 10 to 20%, suggesting the PUP played an important role in the enhancement of the flexibility of the modified TPS sheet. The reaction ratio of PUP used for preparing the modified TPS was 98.5 ± 0.03%, indicating the modification was conducted efficiently because the multifunctional groups of polyurethane microparticles dramatically improved the reaction probability of the PUP modifier. The modified TPS prepared with PUP by adding DMPA showed increasing viscosity and decreasing contact angle due to the hydrophilicity of DMPA.
Role of MicroRNAs 99b, 181a, and 181b in the Differentiation of Human Embryonic Stem Cells to Vascular Endothelial Cells
Authors: Kane Nicole M. , Howard Lynsey , Descamps Betty , Meloni Marco , McClure John , Lu Ruifang , McCahill Angela , Breen Christopher , Mackenzie Ruth M. , Delles Christian , Mountford Joanne C. , Milligan Graeme , Emanueli Costanza , Baker Andrew H. 
Published: January 2012

AbstractMicroRNAs (miRNAs) are short noncoding RNAs, which post-transcriptionally regulate gene expression. miRNAs are transcribed as precursors and matured to active forms by a series of enzymes, including Dicer. miRNAs are important in governing cell differentiation, development, and disease. We have recently developed a feeder- and serum-free protocol for direct derivation of endothelial cells (ECs) from human embryonic stem cells (hESCs) and provided evidence of increases in angiogenesis-associated miRNAs (miR-126 and -210) during the process. However, the functional role of miRNAs in hESC differentiation to vascular EC remains to be fully interrogated. Here, we show that the reduction of miRNA maturation induced by Dicer knockdown suppressed hES-EC differentiation. A miRNA microarray was performed to quantify hES-EC miRNA profiles during defined stages of endothelial differentiation. miR-99b, -181a, and -181b were identified as increasing in a time- and differentiation-dependent manner to peak in mature hESC-ECs and adult ECs. Augmentation of miR-99b, -181a, and -181b levels by lentiviral-mediated transfer potentiated the mRNA and protein expression of EC-specific markers, Pecam1 and VE Cadherin, increased nitric oxide production, and improved hES-EC-induced therapeutic neovascularization in vivo. Conversely, knockdown did not impact endothelial differentiation. Our results suggest that miR-99b, -181a, and -181b comprise a component of an endothelial-miRNA signature and are capable of potentiating EC differentiation from pluripotent hESCs.Disclosure of potential conflicts of interest is found at the end of this article.
Transcription Factor TCF4 Maintains the Properties of Human Corneal Epithelial Stem Cells
Authors: Lu Rong , Qu Yangluowa , Ge Jian , Zhang Lili , Su Zhitao , Pflugfelder Stephen C. , Li De-Quan 
Published: January 2012

Abstract
TCF4, a key transcription factor of Wnt signaling system, has been recently found to be essential for maintaining stem cells. However, its signaling pathway is not well elucidated. This study was to explore the functional roles and signaling pathway of TCF4 in maintaining adult stem cell properties using human corneal epithelial stem cells as a model. With immunofluorescent staining and real-time polymerase chain reaction, we observed that TCF4 was exclusively expressed in the basal layer of human limbal epithelium where corneal epithelial stem cells reside. TCF4 was found to be well colocalized with ABCG2 and p63, two recognized epithelial stem/progenitor cell markers. Using in vitro culture models of primary human corneal epithelial cells, we revealed that TCF4 mRNA and protein were upregulated by cells in exponential growth stage, and RNA interference by small interfering RNA-TCF4 (10-50 nM) transfection blocked TCF4 signaling and suppressed cell proliferation as measured by WST-1 assay. TCF4 silence was found to be accompanied by downregulated proliferation-associated factors p63 and survivin, as well as upregulated cyclin-dependent kinase inhibitor 1C (p57). By creating a wound healing model in vitro, we identified upregulation and activation of β-catenin/TCF4 with their protein translocation from cytoplasm to nuclei, as evaluated by reverse transcription-quantitative real-time polymerase chain reaction, immunostaining, and Western blotting. Upregulated p63/survivin and downregulated p57 were further identified to be TCF4 downstream molecules that promote cell migration and proliferation in wound healing process. These findings demonstrate that transcription factor TCF4 plays an important role in determining or maintaining the phenotype and functional properties of human corneal epithelial stem cells.
Disclosure of potential conflicts of interest is found at the end of this article.
miR-290 Cluster Modulates Pluripotency by Repressing Canonical NF-κB Signaling
Authors: Lüningschrör Patrick , Stöcker Benedikt , Kaltschmidt Barbara , Kaltschmidt Christian 
Published: January 2012

Abstract
Embryonic stem cell (ESC)-specific microRNAs (miRNAs) play a critical role in the maintenance of pluripotency and self-renewal but the complete network between these miRNAs and their broad range of target genes still remains elusive. Here we demonstrate that miR-290 cluster, the most abundant miRNA family in ESCs, targets the NF-κB subunit p65 (also known as RelA) by repressing its translation. Forced expression of p65 causes loss of pluripotency, promotes differentiation of ESCs, and leads to an epithelial to mesenchymal transition. These data define p65 as a novel target gene of miR-290 cluster and provide new insight into the function of ESC-specific miRNAs.
Disclosure of potential conflicts of interest is found at the end of this article.
Can dynamic visualizations improve middle school students' understanding of energy in photosynthesis?
Authors: Ryoo Kihyun , Linn Marcia C. 
Published: January 2012

AbstractDynamic visualizations have the potential to make abstract scientific phenomena more accessible and visible to students, but they can also be confusing and difficult to comprehend. This research investigates how dynamic visualizations, compared to static illustrations, can support middle school students in developing an integrated understanding of energy in photosynthesis. Two hundred 7th‐grade students were randomly assigned to either a dynamic or a static condition and completed a web‐based inquiry unit that encourages students to make connections among energy concepts in photosynthesis. While working on the inquiry unit, students in the dynamic condition interacted with a dynamic visualization of energy transformation, whereas students in the static condition interacted with a series of static illustrations of the same concept. The results showed that students in both conditions added new, scientific ideas about energy transformation and developed a more coherent understanding of energy in photosynthesis. However, when comparing the two conditions, we found a significant advantage of dynamic visualization over static illustrations. Students in the dynamic condition were significantly more successful in articulating the process of energy transformation in the context of chemical reactions during photosynthesis. Students in the dynamic condition also demonstrated a more integrated understanding of energy in photosynthesis by linking their ideas about energy transformation to other energy ideas and observable phenomena of photosynthesis than those students in the static condition. This study, consistent with other research, shows that dynamic visualizations can more effectively improve students' understanding of abstract concepts of molecular processes than static illustrations. The results of this study also suggest that with appropriate instructional support, such as making predictions and distinguishing among ideas, both dynamic visualizations and static illustrations can benefit students. This study underscores the importance of curriculum design in ensuring that dynamic visualizations add value to science instructional materials. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 218–243, 2012
Nearest‐neighbor methods
Authors: Sutton Clifton 
Published: January 2012

AbstractNearest‐neighbor classification is a simple and popular method for supervised classification. The basic method is to classify a query point as being of a certain class if of the k‐nearest neighbors of the query point, more of them belong to this class than to any other class. Variations of the basic method include weighted nearest‐neighbor methods and adaptive nearest‐neighbor methods (which allow some variables to have greater influence than other variables). WIREs Comput Stat 2012, 4:307–309. doi: 10.1002/wics.1195This article is categorized under:

Statistical Learning and Exploratory Methods of the Data Sciences > Clustering and Classification
Statistical Learning and Exploratory Methods of the Data Sciences > Pattern Recognition
Fluorescent Properties of three Zinc(II) Coordination Polymers derived from Flexible N‐(4/3‐Carboxyphenyl)iminodiacetic Acids
Authors: Chai Xiao‐Chuan , Zhao Yan‐Fei , Gong Qiao‐Juan , Liang Yong‐Ping , Zhang Han‐Hui , Chen Yi‐Ping 
Published: January 2012

AbstractThree polymers [Zn2(p‐CPIDA)(OH)]n (1), [Zn2(p‐HCPIDA)2(bipy)(H2O)4]·2H2O (2), and [Zn(m‐HCPIDA)(bipy)]n (3) [p/m‐H3CPIDA = N‐(4/3‐carboxyphenyl) iminodiacetic acid, bipy = 4, 4′‐bipyridine] were hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, X‐ray powder diffraction patterns (XPRD), FTIR spectroscopy, and fluorescence analyses. Compound 1 displays an interesting three‐dimensional framework consisting of novel paddle wheel Zn8O10C2 units, which are further linked by p‐CPIDA3– ligands with versatile coordination modes. In 2, the structural motifs formed by terminal p‐HCPIDA2– ligands and ZnII ions are bridged by ancillary bipy to give a zero‐dimensional Z‐shaped dimer. Compound 3 has an infinite zigzag chain linked by bipy, in which terminal m‐HCPIDA2– ligands alternately run along the chain like flags. Compounds 2 and 3 are further connected by hydrogen bonding and π···π stacking interactions to result in 3D supramolecular frameworks. Moreover, compounds 1–3 exhibit intense solid state fluorescent emissions at room temperature.
Syntheses, Crystal Structures, and Magnetic Properties of Three Transition Metal Complexes Based on a Flexible ­Dipyridyl Ligand and Oxalate
Authors: Cui Zhi‐Hua , Wang Si‐Si , Wang Xiu‐Guang , Gao Dong‐Zhao , Sun Ya‐Qiu , Zhang Guo‐Ying , Xu Yan‐Yan 
Published: January 2012

AbstractThree new complexes [Cu(Hbpma)(ox)Cl]2·8H2O (1), {[Co2(bpma)(ox)2(H2O)2]·6H2O}n (2), and {[Zn2(bpma)(ox)2(H2O)2]·6H2O}n (3) (bpma = N,N′‐bis(3‐pyridylmethyl)amine and ox = oxalate) were synthesized and structurally characterized by single‐crystal X‐ray diffraction. Complex 1 is a bpma‐bridged dinuclear CuII compound, whereas the oxalate only acts as terminal ligand by bidentate chelating mode. Complexes 2 and 3 are isomorphs found to be one‐dimensional coordination polymers bridged by both bpma and ox ligands. The conformation of bpma ligand has a transformation from trans‐gauche mode in complex 1 to trans‐trans one in complexes 2 and 3. The magnetic property of complex 2 shows the occurrence of antiferromagnetic interactions between two adjacent CoII ions.
Hafnium Trialkyls Stabilized by Bulky, Electron‐Rich Aminopyridinates
Authors: Hafeez Muhammad , Kretschmer Winfried P. , Kempe Rhett 
Published: January 2012

AbstractA series of hafnium aminopyridinates were synthesized and spectroscopically analyzed. In addition, selected examples of these hafnium complexes were characterized by X‐ray single crystal structure analysis. The aminopyridinato ligands used here carry an additional dialkylamine substituent to enhance the electron donating ability of the ligands. Structural data and low temperature NMR spectroscopic investigations are indicative of the increased donating ability of the ligands. Ethylene polymerization studies revealed a rather low catalytic activity most likely due to catalyst instability. Details of the deactivation reaction were investigated by NMR spectroscopy.
2Mg(OH)2·MgCl2·2H2O and 2Mg(OH)2·MgCl2·4H2O, Two High Temperature Phases of the Magnesia Cement System
Authors: Dinnebier Robert E. , Oestreich Melanie , Bette Sebastian , Freyer Daniela 
Published: January 2012

AbstractIn the course of investigations relating to magnesia cement the basic magnesium salt hydrates 2Mg(OH)2·MgCl2·2H2O (2‐1‐2 phase) and 2Mg(OH)2·MgCl2·4H2O (2‐1‐4 phase) were found as stable phases in the system MgO‐MgCl2‐H2O at a temperature of T = 120 °C and were characterized by thermal analysis, Raman spectroscopy and X‐ray powder diffraction. The crystal structures of the 2‐1‐2 and 2‐1‐4 phases were determined from high resolution laboratory X‐ray powder diffraction data.Both phases crystallize in space group C2/m with Z = 2 (2‐1‐2: a = 15.3285(3) Å, b = 3.2208(5) Å, c = 8.1096(2) Å, β = 91.99(1)°, V = 400.13(2) Å3; 2‐1‐4: a = 15.1264 Å, b = 3.1715(2) Å, c = 10.5230(1) Å, β = 101.55(1)°, V = 494.60(1) Å3). The main building unit of both crystal structures is made up by infinite triple chains of edge‐linked distorted MgO6 octahedra. In case of the 2‐1‐4 phase, the parallel stacks are in addition separated by interstitial one dimensional zig‐zag chains of disordered Cl– ions and H2O molecules.
Intellectual and neurological functioning in Morquio syndrome (MPS IVa)
Authors: Davison J. E. , Kearney S. , Horton J. , Foster K. , Peet A. C. , Hendriksz C. J. 
Published: January 2012

AbstractMucopolysaccharidosis type IVa (MPS IVa, Morquio syndrome OMIM #253000) is a lysosomal storage disease caused by deficiency in N‐acetylgalactosamine‐6‐sulfatase (GALNS, EC 3.1.6.4; encoded by GALNS gene at 16q24.3). Unlike other MPS disorders involving excessive heparan and dermatan sulfate, Morquio syndrome has not been associated with neurological involvement nor with intellectual impairment as this disorder of keratan sulfate has been described as a purely visceral and skeletal disorder. Neurocognitive assessment was undertaken of MPS IVa patients with age appropriate intellectual tests as well as a Child Behaviour Checklist as part of clinical follow up. Available neuroimaging studies (MRI and MR spectroscopy) were reviewed. Whilst more than half of the overall IQ scores fell in the average range, scores for 3/8 children fell below average. A number of behavioural problems were highlighted, including anxiety/depression, attention and somatic complaints. Subtle neuroimaging abnormalities were demonstrated in over half of the children. These findings present a challenge to existing assumptions about the nature of Morquio A syndrome. A hypothesis regarding the potential role of calcium signalling is explored.
Decreased functional brain connectivity in individuals with early‐treated phenylketonuria: evidence from resting state fMRI
Authors: Christ Shawn E. , Moffitt Amanda J. , Peck Dawn , White Desirée A. , Hilgard Joseph 
Published: January 2012

AbstractPrevious histological and neuroimaging studies have documented structural abnormalities in the white matter of the brain in individuals with early‐treated phenylketonuria (ETPKU). It remains unclear, however, the extent to which the function of the brain's interconnections are impacted by this condition. Presently, we utilized functional magnetic resonance imaging (fMRI) to evaluate the synchronization of neural signals (i.e., functional connectivity) among brain regions comprising the default mode network (DMN) in a sample of 11 individuals with ETPKU and 11 age‐ and gender‐matched neurologically intact controls. The DMN is a group of interconnected brain regions that are known to be generally more active during rest than during task performance. Data analysis revealed decreased functional connectivity among DMN regions for the ETPKU group compared with the control group. Within the PKU group, we also found a significant relationship between blood phenylalanine (phe) levels and the functional connectivity between select regions of the DMN. In conjunction with findings from another recent fMRI study (Christ, Moffitt et al. 2010), the present results suggest that ETPKU‐related deficiencies in functional connectivity are pervasive. The current findings also provide initial evidence that the extent of such impairment may be moderated in part by blood phe levels.
Hyperinsulinaemic hypoglycaemia: genetic mechanisms, diagnosis and management
Authors: Senniappan Senthil , Shanti Balasubramaniam , James Chela , Hussain Khalid 
Published: January 2012

AbstractHyperinsulinaemic hypoglycaemia (HH) is due to the unregulated secretion of insulin from pancreatic β‐cells. A rapid diagnosis and appropriate management of these patients is essential to prevent the potentially associated complications like epilepsy, cerebral palsy and neurological impairment. The molecular basis of HH involves defects in key genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and UCP2) which regulate insulin secretion. The most severe forms of HH are due to loss of function mutations in ABCC8/KCNJ11 which encode the SUR1 and KIR6.2 components respectively of the pancreatic β‐cell KATP channel. At a histological level there are two major forms (diffuse and focal) each with a different genetic aetiology. The diffuse form is inherited in an autosomal recessive (or dominant) manner whereas the focal form is sporadic in inheritance and is localised to a small region of the pancreas. The focal form can now be accurately localised pre‐operatively using a specialised positron emission tomography scan with the isotope Fluroine‐18L‐3, 4‐dihydroxyphenyalanine (18F‐DOPA‐PET). Focal lesionectomy can provide cure from the hypoglycaemia. However the diffuse form is managed medically or by near total pancreatectomy (with high risk of diabetes mellitus). Recent advances in molecular genetics, imaging with 18F‐DOPA‐PET/CT and novel surgical techniques have changed the clinical approach to patients with HH.