bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphoepithelial cysts in the pancreas: MRI of two cases with emphasis of diffusion‐weighted imaging characteristics
Authors: Nam Se Jin , Hwang Ho Kyoung , Kim Hyunki , Yu Jeong‐Sik , Yoon Dong‐Sup , Chung Jae‐Joon , Kim Joo Hee , Kim Ki Whang
Published: September 2010

Pancreatic lymphoepithelial cysts (LECs) are rare pancreatic cystic lesions filled with keratinized material, lined by mature, keratinizing squamous epithelium and surrounded by lymphoid tissue containing few lymphoid follicles. We report two cases of surgically confirmed pancreatic LECs showing a profound restriction of water molecules on diffusion‐weighted (DWI) magnetic resonance imaging (MRI). For pancreatic cystic lesions showing lack of molecular motion on DWI with or without thin marginal enhancement on contrast material‐enhanced imaging, LECs consisting of internally keratinized materials with restricted diffusion should be considered in differential diagnoses even though they cannot always be easy to distinguish from other focal pancreatic lesions containing mucin, blood clot, or nonliquefactive necrosis. J. Magn. Reson. Imaging 2010;32:692–696. © 2010 Wiley‐Liss, Inc.
Imaging biomarkers of cardiovascular disease
Authors: Wang Jinnan , Balu Niranjan , Canton Gador , Yuan Chun
Published: September 2010

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Current clinical techniques that rely on stenosis measurement alone appear to be insufficient for risk prediction in atherosclerosis patients. Many novel imaging methods have been developed to study atherosclerosis progression and to identify new features that can predict future clinical risk. MRI of atherosclerotic vessel walls is one such method. It has the ability to noninvasively evaluate multiple biomarkers of the disease such as luminal stenosis, plaque burden, tissue composition and plaque activity. In addition, the accuracy of in vivo MRI has been validated against histology with high reproducibility, thus paving the way for application to epidemiological studies of disease pathogenesis and, by serial MRI, in monitoring the efficacy of therapeutic intervention. In this review, we describe the various MR techniques used to evaluate aspects of plaque progression, discuss imaging‐based measurements (imaging biomarkers), and also detail their validation. The application of plaque MRI in clinical trials as well as emerging imaging techniques used to evaluate plaque compositional features and biological activities are also discussed. J. Magn. Reson. Imaging 2010;32:502–515. © 2010 Wiley‐Liss, Inc.
Susceptibility mapping as a means to visualize veins and quantify oxygen saturation
Authors: Haacke E.M. , Tang J. , Neelavalli J. , Cheng Y.C.N.
Published: September 2010

Purpose:

To create an orientation‐independent, 3D reconstruction of the veins in the brain using susceptibility mapping.

Materials and Methods:

High‐resolution, high‐pass filtered phase images usually used for susceptibility weighted imaging (SWI) were used as a source for local magnetic field behavior. These images were subsequently postprocessed using an inverse procedure to generate susceptibility maps of the veins. Regularization and interpolation of the data in k‐space of the phase images were used to reduce reconstruction artifacts. To understand the effects of artifacts, and to fine‐tune the methodology, simulations of blood vessels were performed with and without noise.

Results:

With sufficient resolution, major veins in the brain could be visualized with this approach. The usual geometry‐dependent phase dipole effects are removed by this processing, leaving basically images of the veins. Different sized vessels show a different level of contrast depending on their partial volume effects. Vessels that are 8 mm or 16 mm in size show quantitative values expected for normal oxygen saturation levels. Smaller vessels show smaller values due to errors in the methodology and due to partial volume effects. Larger vessels show a bias toward a reduced susceptibility approaching 90% of the expected value. Limitations of the method and artifacts related to different sources of errors are demonstrated.

Conclusion:

Susceptibility maps can successfully create venograms of the brain with varying levels of contrast‐to‐noise depending on the size of the vessel. Partial volume effects render this approach more useful as an imaging tool or a visualization tool, although certain larger vessels have measured susceptibilities close to expected values associated with normal blood oxygen saturation levels. J. Magn. Reson. Imaging 2010;32:663–676. © 2010 Wiley‐Liss, Inc.
T2‐weighted 3D fast spin echo imaging with water–fat separation in a single acquisition
Authors: Madhuranthakam Ananth J. , Yu Huanzhou , Shimakawa Ann , Busse Reed F. , Smith Martin P. , Reeder Scott B. , Rofsky Neil M. , Brittain Jean H. , McKenzie Charles A.
Published: September 2010

Purpose:

To develop a robust 3D fast spin echo (FSE) T2‐weighted imaging method with uniform water and fat separation in a single acquisition, amenable to high‐quality multiplanar reformations.

Materials and Methods:

The Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation (IDEAL) method was integrated with modulated refocusing flip angle 3D‐FSE. Echoes required for IDEAL processing were acquired by shifting the readout gradient with respect to the Carr‐Purcell‐Meiboom‐Gill echo. To reduce the scan time, an alternative data acquisition using two gradient echoes per repetition was implemented. Using the latter approach, a total of four gradient echoes were acquired in two repetitions and used in the modified IDEAL reconstruction.

Results:

3D‐FSE T2‐weighted images with uniform water–fat separation were successfully acquired in various anatomies including breast, abdomen, knee, and ankle in clinically feasible scan times, ranging from 5:30–8:30 minutes. Using water‐only and fat‐only images, in‐phase and out‐of‐phase images were reconstructed.

Conclusion:

3D‐FSE‐IDEAL provides volumetric T2‐weighted images with uniform water and fat separation in a single acquisition. High‐resolution images with multiple contrasts can be reformatted to any orientation from a single acquisition. This could potentially replace 2D‐FSE acquisitions with and without fat suppression and in multiple planes, thus improving overall imaging efficiency. J. Magn. Reson. Imaging 2010;32:745–751. © 2010 Wiley‐Liss, Inc.
Evaluation of intraneural ganglion cysts using three‐dimensional fast spin echo‐cube
Authors: Shahid Kameron R. , Spinner Robert J. , Skinner John A. , Felmlee Joel P. , Bond Jeffrey R. , Stanley David W. , Amrami Kimberly K.
Published: September 2010

Purpose:

To compare conventional two‐dimensional fast spin echo (FSE) MRI sequences with a three‐dimensional FSE extended echo train acquisition method, known as Cube, in the evaluation of intraneural ganglion cysts. Also, to demonstrate that Cube enables the consistent identification and thorough characterization of the cystic joint connection, and therefore improves patient care by superior preoperative planning.

Materials and Methods:

Six patients with intraneural ganglia in the knee region (five involving the peroneal and one the tibial nerve) were evaluated using both conventional FSE MR sequences and the Cube sequence. Studies were interpreted by the consensus of three board certified musculoskeletal radiologists and one peripheral nerve neurosurgeon. Surgical correlation was available in five of the six cases.

Results:

Both imaging methods demonstrated the cysts and at least part of their joint connections after variable amount of postprocessing. Cube proved superior to conventional imaging in its ability to acquire isotropic data that could easily be reconstructed in any plane and its ability to resolve fine anatomical details.

Conclusion:

Cube is a new MR pulse sequence that enables the consistent identification of the intraneural ganglion cyst joint connection. We believe that improved visualization and characterization of the entire cyst will improve patient outcomes by facilitating more accurate surgical intervention. J. Magn. Reson. Imaging 2010;32:714–718. © 2010 Wiley‐Liss, Inc.
MRI quantification of splenic iron concentration in mouse
Authors: Hitti Eric , Eliat Pierre‐Antoine , Abgueguen Emmanuelle , Ropert Martine , Leroyer Patricia , Brissot Pierre , Gandon Yves , Saint‐Jalmes Herve , Loréal Olivier
Published: September 2010

Purpose:

To quantify hepatic and splenic iron load, which is a critical issue for iron overload disease diagnosis. MRI is useful to noninvasively determine liver iron concentration, but not proven to be adequate for robust evaluation of splenic iron load. We evaluated the usefulness of MRI‐derived parameters to determine splenic iron concentration in mice.

Materials and Methods:

A mouse model of experimental iron load was used. Multi‐echo spin‐echo images of liver and spleen were acquired at 4.7 Tesla. The parameters were tested at all echoes with and without an external reference. Splenic and hepatic iron concentrations were determined using biochemical assay as the gold standard.

Results:

Our results show that (i) use of an internal or external reference is essential; (ii) optimal echo times were TE = 19.5 ms and TE = 32.5 ms for the liver and spleen, respectively; (iii) in the liver, the relationship between biochemical and MRI iron concentration determinations is logarithmic; (iv) in the spleen, the best relationship is an inverse function.

Conclusion:

A single spin‐echo sequence allows robust estimation of hepatic and splenic iron content. Parameters classically used for hepatic iron concentration cannot be applied to splenic iron determination, which requires both the specific sequence and the adapted fitting function. J. Magn. Reson. Imaging 2010;32:639–646. © 2010 Wiley‐Liss, Inc.
Correlation of putative iron content as represented by changes in R2* and phase with age in deep gray matter of healthy adults
Authors: Haacke E. Mark , Miao Yanwei , Liu Manju , Habib Charbel A. , Katkuri Yashwanth , Liu Ting , Yang Zhihong , Lang Zhijin , Hu Jiani , Wu Jianlin
Published: September 2010

Purpose:

To establish a correlation between putative iron content using susceptibility weighted imaging (SWI) phase and T2* weighted magnitude values in the basal ganglia and the thalamus as a function of age in healthy human brains.

Materials and Methods:

One hundred healthy adults (range, 20–69 years; mean, 43 years) were evaluated for this study using a gradient echo sequence. The original magnitude and high pass filtered phase data were analyzed as proxy variables for iron content in the substantia nigra, red nucleus, globus pallidus, putamen, caudate nucleus, thalamus, and pulvinar thalamus. Each structure was broken into two parts, a high iron content region and a low iron content region.

Results:

Both magnitude and phase data showed an increase in putative iron content with age. However, the high iron content region revealed two new pieces of information: both the average iron content per pixel and the area of high iron increased with age. Furthermore, significant increase in iron uptake as a function of age was found past the age of 40.

Conclusion:

A two region of interest analysis of iron is a much more sensitive means to evaluate iron content change over time. Contrary to the current belief that iron content increases level off with age, the putative iron deposition in the high iron content region is seen to increase with age. J. Magn. Reson. Imaging 2010;32:561–576. © 2010 Wiley‐Liss, Inc.
In vivo magnetic resonance elastography of human brain at 7 T and 1.5 T
Authors: Hamhaber Uwe , Klatt Dieter , Papazoglou Sebastian , Hollmann Maurice , Stadler Jörg , Sack Ingolf , Bernarding Johannes , Braun Jürgen
Published: September 2010

Purpose:

To investigate the feasibility of quantitative in vivo ultrahigh field magnetic resonance elastography (MRE) of the human brain in a broad range of low‐frequency mechanical vibrations.

Materials and Methods:

Mechanical vibrations were coupled into the brain of a healthy volunteer using a coil‐driven actuator that either oscillated harmonically at single frequencies between 25 and 62.5 Hz or performed a superimposed motion consisting of multiple harmonics. Using a motion sensitive single‐shot spin‐echo echo planar imaging sequence shear wave displacements in the brain were measured at 1.5 and 7 T in whole‐body MR scanners. Spatially averaged complex shear moduli were calculated applying Helmholtz inversion.

Results:

Viscoelastic properties of brain tissue could be reliably determined in vivo at 1.5 and 7 T using both single‐frequency and multifrequency wave excitation. The deduced dispersion of the complex modulus was consistent within different experimental settings of this study for the measured frequency range and agreed well with literature data.

Conclusion:

MRE of the human brain is feasible at 7 T. Superposition of multiple harmonics yields consistent results as compared to standard single‐frequency based MRE. As such, MRE is a system‐independent modality for measuring the complex shear modulus of in vivo human brain in a wide dynamic range. J. Magn. Reson. Imaging 2010;32:577–583. © 2010 Wiley‐Liss, Inc.
Association between contrast‐enhanced MR images and blood–brain barrier disruption following transcranial focused ultrasound
Authors: Yang Feng‐Yi , Horng Shih‐Cheng , Lin Yu‐Shi , Kao Yi‐Hsuan
Published: September 2010

Purpose:

To investigate the correlation between the contrast‐enhanced magnetic resonance imaging (MRI) signal and the duration of blood–brain barrier (BBB) disruption induced by focused ultrasound (FUS).

Materials and Methods:

FUS was applied to 45 rat brains in the presence of microbubbles, and these rats were scanned on a 3T MRI system at several timepoints. The rat brains were then studied using contrast‐enhanced spin echo T1‐weighted images. At the same time, BBB disruption was evaluated based on Evans blue (EB) extravasation. The relationship between the normalized signal intensity change of the MRI and EB extravasation was analyzed by least‐squares linear regression and the calculation of correlation coefficients.

Results:

When MRI enhancement was quantitatively evaluated by EB extravasation, a strong correlation between the normalized signal intensity change of the MRI and EB extravasation was identified during BBB disruption after sonication. However, the correlation coefficient decreased as BBB closure occurred after sonication ended.

Conclusion:

The contrast‐enhanced MRI signal can potentially be used to evaluate the amount of chemotherapeutic agents entering the targeted tissue, but the accuracy of the assessment will be affected by the time interval since sonication. J. Magn. Reson. Imaging 2010;32:593–599. © 2010 Wiley‐Liss, Inc.
Decline in hepatitis B infection observed after 11 years of regional vaccination among Danish drug users
Authors: Mössner B.K. , Skamling M. , Jørgensen T. Riis , Georgsen J. , Pedersen C. , Christensen P.B.
Published: September 2010

The aims of this study were to determine the current prevalence of viral hepatitis and HIV among drug users, and to compare this prevalence with previous findings in the same geographical region. Cross‐sectional surveys of drug users attending treatment centers on the island of Funen with approximately 500,000 inhabitants were administered in 1996 and 2007. The 2007 prevalence estimates were: anti‐HBc 50.2%, HBsAg 0.9%, anti‐HCV 66.8%, HCV‐RNA 40%, and anti‐HIV 1.1%. The corresponding 1996 prevalence values were: anti‐HBc 70% (P < 0.0001), HBsAg 9.8% (P < 0.0001), anti‐HCV 82.8% (P < 0.0001), HCV‐RNA 56.3% (P = 0.002), and anti‐HIV 1% (P = 1). The 2007 prevalence of viral hepatitis decreased due to the increasing proportion of non‐injectors. Among injectors, the prevalence remained unchanged except for a significant decrease in HBsAg. The 2007 prevalence of ongoing HBV infection among infected (HBsAg/anti‐HBc proportion) was the lowest that to our knowledge has been reported among drug‐users. Vaccination coverage among susceptible persons tested in 2007 was 24%, compared to 0.7% in 1996. Therefore, despite an unchanged prevalence of anti‐HBc among injecting drug users, a highly significant drop in HBsAg prevalence was seen during the last decade. This observation may be linked causally to an increase in hepatitis B vaccination of the susceptible population. Our findings suggest that even incomplete vaccination, without persistent protective anti‐HBs levels, may induce an immune memory sufficient to prevent chronic infection upon transmission. J. Med. Virol. 82:1635–1639, 2010. 2010 Wiley‐Liss, Inc.
Human metapneumovirus genotypes and severity of disease in young children (n = 100) during a 7‐year study in Dijon hospital, France
Authors: Pitoiset Cécile , Darniot Magali , Huet Frédéric , Aho Serge‐Ludwig , Pothier Pierre , Manoha Catherine
Published: September 2010

Human metapneumovirus is a cause of respiratory tract infections at all ages. Our objectives were to analyze the distribution of the A and B genotypes over 7 years in Dijon and to investigate a possible association between hMPV genotypes and disease severity. During 2002–2009, we genotyped the 100 isolates from children <3 years old with hMPV. Phylogenetic analysis indicated a change in the distribution of hMPV genotype over the years. Severity was then measured by detailed clinical evaluation. The hospitalization rate was greater when genotype B was involved 72.5% versus 53.3% (P = 0.054). Those infected with genotype B tended to have a higher clinical score, as measured by Vicente et al. 2006 (P = 0.07). We showed that, although clinical severity is not clearly associated with hMPV genotype in this study, pathological signs on chest X‐ray were observed more often in B subgroup (P < 0.01). J. Med. Virol. 82:1782–1789, 2010. © 2010 Wiley‐Liss, Inc.
Separation optimization of quercetin, hesperetin and chrysin in honey by micellar liquid chromatography and experimental design
Authors: Hadjmohammadi Mohammad Reza , Nazari S. Saman S. J.
Published: September 2010

The chemometrics approach was applied for the separation optimization of flavonoid markers (quercetin, hesperetin and chrysin) in honey using micellar liquid chromatography (MLC). The investigated method combines SPE of flavonoids from honey using C18 cartridge and their separation and quantification by micellar liquid chromatography. A two level full factorial design was carried out to evaluate the effect of four experimental factors including concentration of SDS, alkyl chain length of the alcohol used as the organic modifier (N), volume percentage of the organic modifier (Vm) and volume percentage of acetic acid (AcOH) in mobile phase on analytes retention times. Experiments for analytes retention times modeling and optimization of separation were performed according to central composite design. Multiple linear regression method was used for the construction of the best model based on experimental retention times. Pareto optimal method was used to find suitable compatibility between resolution and analysis time of analytes in honey. The optimum mobile phase composition for separation and determination of analytes in honey were [SDS]=0.124 mol/L; 7.8% v/v ethanol and 5.0% v/v AcOH. Limits of detection and linear range of flavonoid markers were 0.0079–0.0126, 0.05–50.0 mg/L, respectively.
The secrets of resilient leaders
Authors: Shambaugh Rebecca
Published: September 2010

Those who thrive show resilience, the capacity to bounce back from misfortune, disruptive change, and failures. “Whether you are at the top of your organization, leading a team, or volunteering in your community, eventually you are sure to face a difficult situation or disruptive change,” Shambaugh writes. She describes four secrets effective leaders use to tap into their own resilience and cultivate a more resilient culture within the organization.
Cerebrospinal fluid tau and phosphorylated tau protein are elevated in corticobasal syndrome
Authors: Aerts M.B. , Esselink R.A.J. , Bloem B.R. , Verbeek M.M.
Published: September 2010

Differentiating corticobasal syndrome (CBS) from progressive supranuclear palsy (PSP) and idiopathic Parkinson's disease (PD) can be difficult. To investigate the additional value of cerebrospinal fluid (CSF) biomarkers in the diagnostic differentiation of parkinsonism, we analyzed the CSF concentrations of total protein, lactate and brain specific proteins amyloid‐β42 protein, tau protein (t‐tau), and tau protein phosphorylated at Thr181 (p‐tau), in CSF samples from patients with PSP (n = 21), CBS (n = 12), and PD (n = 28). CBS patients demonstrated higher concentrations of t‐tau and p‐tau compared with PSP and PD patients. In discriminating CBS and PD, t‐tau offered the best combination of sensitivity (75%) and specificity (90.9%), followed by p‐tau (sensitivity 87.5% and specificity 75%). The p‐tau/t‐tau ratio resulted in sensitivity of 84.2% and specificity of 66.7% in discriminating PSP and CBS. In conclusion, our results suggest that CSF parameters are of additional value in the diagnostic differentiation of CBS and PD. © 2010 Movement Disorder Society
Entdeckungsgeschichte des Nitroglycerins. Ein Sprengstoff wird Medikament
Authors: Remane Horst , Remane Yvonne
Published: September 2010

Im Jahre 1847 entdeckte der italienische Chemiker Ascanio Sobrero mit dem Nitroglycerin (Glyceroltrinitrat) eine Verbindung, die an Sprengkraft das herkömmliche Schwarzpulver um ein Vielfaches übertraf. Die Neigung dieser Verbindung zu spontaner Explosion war indes ein großes Hindernis für die praktische Nutzung. Mit der Fixierung des Nitroglycerins auf einem porösen Silikat gelang es dann dem Schweden Alfred Nobel dieses Hindernis zu überwinden. Als Nobels Dynamit wurde Nitroglycerin schnell zu einem gefragten Gebrauchssprengstoff. Die Erkenntnis, dass Nitroglycerin im Organismus eine Dilatation der Blutgefäße bewirkt, öffnete einer weiteren wichtigen Anwendung das Tor. Nitroglycerin wurde und wird bis heute als schnell wirksames Medikament zur Behandlung akuter Angina‐pectoris‐Anfälle eingesetzt. Mehr als 100 Jahre lang gab es über die physiologische Wirkung des Nitroglycerins nur Vermutungen. Erst in den 1970er Jahren konnte nachgewiesen werden, dass die Wirkung des Medikaments auf dem Stickstoffmonoxid (NO), einem Abbauprodukt des Nitroglycerins beruht. Dies war insofern überraschend, als man NO bis dahin hauptsächlich als Umweltgift kannte.
PDE5‐Inhibitoren in der Behandlung der pulmonalen Hypertonie. Beeinflussung des NO‐Signalweges
Authors: Dumitrescu Daniel , Erdmann Erland , Rosenkranz Stephan
Published: September 2010

Die PDE5‐Inhibitoren, ursprünglich entwickelt für die Therapie der erektilen Dysfunktion, sind derzeit eine etablierte Therapie in der Behandlung der PAH. Zwei der drei verfügbaren Substanzen, Sildenafil und Tadalafil, sind momentan zur Therapie der PAH zugelassen. Die Wirksamkeit der PDE5‐Inhibitoren beruht auf der selektiven pulmonalen Vasodilatation durch die Hemmung des cGMP‐Abbaus in pulmonalen, glatten Gefäßmuskelzellen. Dadurch wird – vorzugsweise in gut belüfteten Lungenarealen – eine pulmonale Vasodilatation erreicht, so dass die pulmonale Hämodynamik und die Oxygenierung des pulmonal arteriellen Blutes bei gleichzeitiger Verringerung der Rechtsherzbelastung verbessert werden. Die Therapie ist gut verträglich, es gibt klassenabhängige und substanzabhängige Nebenwirkungen, die nur in seltenen Fällen schwerwiegend ausgeprägt sind. Die Wirksamkeit und Sicherheit der Substanzen konnte in großen, doppelblinden, placebo‐kontrollierten Studien nachgewiesen werden. Langzeitergebnisse und Überlebensdaten sowie die Rolle der PDE5‐Inhibitoren in der Kombinationstherapie der PAH werden derzeit in klinischen Studien untersucht.
Großangriff gegen Plasmodien
Authors: Holzgrabe Ulrike
Published: September 2010

Laut neuesten WHO‐Berichten erkranken jährlich 2,5 Millionen Menschen an Malaria und ca. 900.000 Menschen sterben an dieser Infektion. Zumeist sind afrikanische Kinder, die südlich der Sahara leben, davon betroffen. Seit 1996 ist kein neuer Wirkstoff gegen Malaria auf den Markt gekommen und auch die Entwicklung von Impfstoffen gestaltet sich sehr schwierig. Dem stehen zunehmende Resistenzen gegen die auf dem Markt befindlichen Wirkstoffe entgegen.
Caregivers' perspectives on barriers to transcranial doppler screening in children with sickle‐cell disease
Authors: Bollinger Lindsay M. , Nire Kidan G. , Rhodes Melissa M. , Chisolm Deena J. , O'Brien Sarah H.
Published: September 2010

Background

Current guidelines recommend that children with HbSS or HbSβ°thal undergo yearly transcranial Doppler screenings (TCD) to identify those at high risk for stroke. Compliance is low with yearly TCD screenings. Our objective was to describe caregiver experiences and knowledge of TCD screenings as well as barriers that may prevent screening.

Procedure

Qualitative, in‐depth interviews structured around the Health Belief Model were conducted with 36 caregivers of children eligible for annual TCD screenings. Interviews were coded and general themes were extracted.

Results

Two‐thirds (69%) of caregivers believed that stroke occurs sometimes (33%) or frequently (36%) in children with sickle‐cell disease (SCD). Lack of knowledge was the most commonly described barrier to annual TCD screening, with 22% of caregivers reporting no knowledge of screening, and 42% unaware that the screen should be performed annually. Lack of self‐efficacy and fear of chronic transfusions were other barriers endorsed by caregivers. Barriers less commonly identified (endorsed by <10% of caregivers) included financial barriers, transportation issues, missed appointments, and hours of radiology clinic. Fifty‐eight percent of the caregivers' children with SCD had undergone a TCD in the 18 months prior to the study interview.

Conclusions

From the caregiver perspective, lack of knowledge and low self‐efficacy play a larger role than practical barriers in compliance with annual TCDs. Ongoing education at multiple patient encounters and encouragement of caregivers' empowerment and role in obtaining annual screenings may increase TCD compliance. Pediatr Blood Cancer. 2010;56:99–102. © 2010 Wiley‐Liss, Inc.
From acyclic dialkylcarbene to the unsaturated cyclic heteroatom substituted ones: a survey of stability
Authors: Kassaee M. Z. , Ghambarian M. , Shakib F. A. , Momeni M. R.
Published: September 2010

In regard to the worldwide interest in synthesis and application of stable carbenes,ab initioand DFT calculations (CCSD(T)/6‐311G*//QCISD/6‐31G* and B3LYP/AUG‐cc‐pVTZ//B3LYP/6‐31 + G* levels) are employed to reach at a series of symmetrically substituted diheteroatom carbenes. In this way the multiplicity, stability, and reactivity of diethylcarbene and its saturated and unsaturated cyclic congeners are compared and contrasted to the corresponding disilyl‐, diamino‐, diphosphino‐, dioxy‐, and dithiocarbenes. The investigations reveal the enlargement of the singlet–triplet energy gaps (ΔES‐T) in the order of (amino ≈ oxy) > thio > phosphino > alkyl > silyl. The observed trend is thoroughly analyzed applying appropriate isodesmic reactions which differentiate the substituent effects on each of the singlet and triplet states of all the carbenes. In contrast to previous reports, it is found that π‐donor/σ‐acceptor amino substituents stabilize not only the singlet but also the triplet states. The effects of cyclization and unsaturation are also probed in each series of the symmetrically substituted carbenes. The reactivity of the species is discussed in terms of nucleophilicity, electrophilicity, and proton affinity. Copyright © 2010 John Wiley & Sons, Ltd.
The Kataura plot for single wall carbon nanotubes on top of crystalline quartz
Authors: Soares Jaqueline S. , Cançado Luiz G. , Barros Eduardo B. , Jorio Ado
Published: September 2010

In this work, we have studied the radial breathing mode (RBM) resonance Raman spectra of single‐wall carbon nanotube serpentines. Each serpentine consists of a series of straight, parallel, and regularly spaced segments, connected by alternating U‐turns formed on top of crystalline miscut quartz. We compare our ωRBM and Eii values with the results in the literature and find a strong environmental effect related to the tube–substrate interaction. We establish experimentally the ${\omega} _{{\rm RBM}} \, = \,(227/d_{{\rm t}} )\sqrt {1 + (0.082\,\pm \,0.009)d_{{\rm t}}^{2} } $ relation between RBM frequency (ωRBM) and tube diameter (dt), with a 100 ± 30 meV downshift in the optical transition energies with respect to the Eii values measured for the standard “super‐growth” samples.
Metal/semiconductor separation of single‐wall carbon nanotubes by selective adsorption and desorption for agarose gel
Authors: Tanaka Takeshi , Urabe Yasuko , Nishide Daisuke , Liu Huaping , Asano Satoshi , Nishiyama Satoko , Kataura Hiromichi
Published: September 2010

Metallic and semiconducting single‐wall carbon nanotubes (SWCNTs) were separated by selective adsorption and desorption using agarose gel beads and SWCNTs/sodium dodecyl sulfate dispersion. Comparison to the batch method, the purities of metallic and semiconducting SWCNTs obtained by a column method were improved to 90 and 95%, respectively. When linear‐gradient elution was applied to the column method, semiconducting SWCNTs and presumed mixed bundles could be separated into early‐ and late‐eluted fractions, respectively. In the semiconducting fractions, chirality separation was also detected.
Broadened second excitonic transition of single‐walled carbon nanotubes in photoluminescence excitation spectroscopy
Authors: Heeg Sebastian , Hatting Benjamin , Dantz Marcus , Reich Stephanie
Published: September 2010

In this paper, we investigate how photoluminescence excitation spectra of single‐walled carbon nanotubes are influenced by experimental conditions. The use of incoherent light sources leads to a broadening of the second excitonic transition. We describe the broadening by a straight forward simulation and deliver the width of the second excitonic transition free of experimental influences. A set of simulated data allows for the correction of experimental influences for arbitrary nanotubes chiralities and excitation bandpasses.
Diameter‐selective desorption of semiconducting single‐wall carbon nanotubes from agarose gel
Authors: Liu Huaping , Tanaka Takeshi , Feng Ye , Kataura Hiromichi
Published: September 2010

Single‐wall carbon nanotubes (SWCNTs) were separated into metallic (M‐) and semiconducting (S‐) parts using agarose gel column chromatography method. Due to their weak interaction with agarose gel, M‐SWCNTs directly passed through the column with SDS solution while S‐SWCNTs were trapped in the gel. Then S‐SWCNTs were desorbed and eluted with sodium deoxycholate (DOC) solution from the gel. It was found that by successively increasing DOC concentration for the elution, smaller‐diameter S‐SWCNTs were firstly eluted with the lower‐concentration DOC solutions and then larger‐diameter S‐SWCNTs were eluted with the higher‐concentration DOC solutions. Thus, a kind of diameter sorting of S‐SWCNTs was achieved. We also found that the relative concentration of M‐SWCNTs in the earlier eluted smaller‐diameter S‐SWCNT fractions was much lower than that in the later eluted larger‐diameter S‐SWCNT fractions, indicating higher‐purity S‐SWCNTs can be obtained by selective fractional collection.
Semiconductors for plasmonics and metamaterials
Authors: Naik Gururaj V. , Boltasseva Alexandra
Published: September 2010

Plasmonics has conventionally been in the realm of metal‐optics. However, conventional metals as plasmonic elements in the near‐infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals with semiconductors can alleviate these problems if only semiconductors could exhibit negative real permittivity. Aluminum doped zinc oxide (AZO) is a low loss semiconductor that can show negative real permittivity in the NIR. A comparative assessment of AZO‐based plasmonic devices such as superlens and hyperlens with their metal‐based counterparts shows that AZO‐based devices significantly outperform at a wavelength of 1.55 µm. This provides a strong stimulus in turning to semiconductor plasmonics at the telecommunication wavelengths. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fe valence state at the surface of the Fe0.5Cu0.5Cr2S4 spinel
Authors: Taubitz Christian , Hu Zhiwei , Hollmann Nils , Chin Yi‐Ying , Kuepper Karsten , Tsurkan Vladimir , Lin H.‐J. , Chen C. T. , Tjeng L. H. , Neumann Manfred
Published: September 2010

Here we present X‐ray absorption measurements of a vacuum cleaved Fe0.5Cu0.5Cr2S4 single crystal. Measurements at different positions on the cleaved sample surface clearly reveal a difference between the valence state of the Fe ions in the sur‐ face layers and the valency of the Fe ions present in the bulk. These results confirm the findings of recent measurements outlined previously. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Eine Methode der Dehydrierung von Sekundären Alkoholen zu Ketonen. I. Zur Herstellung von Sterinketonen und Sexualhormonen
Authors: Oppenauer R. V.
Published: September 2010

Eine Methode zur Bereitung von kompliziert gebauten Ketonen der Sterinreihe aus den entsprechenden Alkoholen wird beschrieben.

Sie besteht darin, dass Sterinalkohole durch Ketone, z.B. Aceton, in Gegenwart von tert. Aluminium‐Alkoholaten zu den entsprechenden Ketonen dehydriert werden.

Die dabei erhaltenen Ausbeuten sind ausgezeichnet, ausserdem können auf diese Weise Ketone bereitet werden, die auf anderem Wege bisher nicht zugänglich waren (Ergosta‐trienon).
Die Krystallstruktur des Ammonium‐, Kalium‐, Rubidium‐ und Cäsiumpalladiumhexa‐chlorids und ‐Bromids
Authors: Ketblaar J. A. A. , van Walsem J. F.
Published: September 2010

Die Krystallstrukturen von K2‐, (NH4)2‐, Rb2‐ und Cs2PdCl6, und von K2, (NH4)2‐, Rb2‐ und Cs2PdBr6 gehören zum K2PtCl6‐Typus oder Jl1‐Typus. Angegeben werden Elementarabstände und Parameter.
Éthers de L'Acide Méthanetricarboxylique
Authors: Backer H. J. , Lolkema J.
Published: September 2010

Une série d'éthers de l'acide méthanetricarboxylique a été préparée par introduction d'un troisième groupe carboxalkyle dans les éthers maloniques. Les éthers aliphatiques examinés sont liquides (l'éther décylique fond à 15°). Les éthers aromatiques, dont aucun représentant n'était connu, cristallisent aisément; on les obtient par l'intermédiaire d'un dérivé magnésien des éthers maloniques.
The preparation and dipole moments of heterocyclic five‐membered rings with one heterocyclic atom
Authors: de Vries Robles H.
Published: September 2010

The following compounds have been prepared, and the dipole moments determined in benzene at 20.0° C using a new method of calculation, based on that given by Hedestrand.magnified image
On the formation of higher aliphatic ketones in the thermal decomposition of fat
Authors: Holleman L. W. J. , Koolhaas D. R.
Published: September 2010

It is shown, that on heating fats at temperatures ranging from 200° to 350°, especially in the presence of catalysts like iron, higher aliphatic ketones are formed by the interaction of pairs of fatty acid molecules. In the case of coconut oil, one of these ketones has been isolated and proved to be the hitherto unknownn‐12‐pentacosanone.
p‐Nitrobenzazide andp‐nitrophenyl isocyanate as reagents for the identification of amines
Authors: Sah Peter P. T.
Published: September 2010

Fifty crystallinep‐nitrophenyl‐ureas have been prepared by the condensation of eitherp‐nitrobenzazide or its pyrolysis product,p‐nitrophenyl isocyanate, with various types of amines in boiling toluene solution. The yields were in general very high and the derivatives were suitable for the purpose of identification.
On indigo. V. A benziminazoline‐derivative, isomeric with indigo
Authors: van Alphen J.
Published: September 2010

2‐(1′ : 3′‐Diketo‐hydrindylidene‐2′)‐benziminazoline is prepared by the condensation of 2‐methylbenziminazole and phthalic anhydride. This compound may be considered as being derived from indigo by interchanging imino and keto groups. Thus in one half of the molecule two imino groups are present and in the other half two keto groups. In many respects it resembles indigo, with the exception that its colour is yellow. Its constitution is proved by the fact, that 2‐ethyl‐ and 2‐benzyl‐benziminazoles do not give analogous products with phthalic anhydride.
Über das Koordinationsvermögen phenylierter Aethylendiamine. II. Verhalten von razemischem und aktivem Stilbendiamin
Authors: Lifschitz I. , Bos J. G.
Published: September 2010

Im Gegensatz zur meso‐Verbindung besitzen razemisches und aktives Stilbendiamin nahezu normales Koordinationsvermögen und sehr viel geringere Neigung zur Bildung gelber Tetramminnickelsalze. Es wird eine grössere Anzahl von Komplexverbindungen dieser Amine beschrieben und magnetisch sowie polarimetrisch untersucht. Auf Grund der vorliegenden Beobachtungen wird die Konstitution der gelben Nickelkomplexe diskutiert und ihre Formulierung als pseudo‐Koordinationsverbindungen (Nickel‐Ammoniumsalze) begründet.
Die Oxydation von Gasförmigem Acetaldehyd durch Sauerstoff
Authors: Bodenstein Max
Published: September 2010

Alte Versuche über diese Reaktion sind fortgeführt worden und haben zu der Erkenntnis geführt, dass die Reaktionsketten an der Wand beginnen, und zwar mit einer Umsetzung von Aldehyd mit der aktiven Form der Persäure, und beendet werden entweder durch eine Spaltung der letzteren oder durch ihre Reaktion mit Sauerstoff. Die aktive Form der Persäure ist das Radikal CH3C( O) (‐O‐O‐), die des Aldehyds das Radikal Acetyl. Diese Auffassung ist mit allen von den verschiedenen Forschern gemachten Beobachtungen im Einklang.
The determination of ecgonine alkaloids in coca leaves
Authors: de Jong A. W. K.
Published: September 2010

A method is communicated by which it is possible to obtain from coarsely pulverised coca leaves, as they are sold at Amsterdam, the same quantity of cocaines and methyl ester of l‐ecgonine as is obtained from finely pulverised leaves. By converting the unknown ester of l‐ecgonine from the coca leaves into l‐cocaine it is proved that it is the methyl ester, which is present. This ester is present also in Cusko leaves.
A study on the physical constants of a number of alkanes and cycloalkanes: II. Additive and constitutional influences on molecular refraction, dispersion and parachor
Authors: Wibaut J. P. , Langedijk S. L.
Published: September 2010

Values of the molecular refraction, calculated according to the formulae of Lorentz‐Lorenz or of Gladstone‐Dale are given for five different wave lenghts for a number of normal and branched alkanes and for a number of cyclanes. Additive and constitutional influences on molecular refraction and parachor are discussed. Exact values for the refraction equivalents of CH2C and H are given. Dispersions, specific and molecular dispersions have been calculated; the influence of homology and isomerism on the dispersion magnitudes is discussed.

The temperature coefficients of the specific gravities and of the refractive indices (λ = 5876) have been calculated.
On the formation of 3, 3‐dimethylcyclohexanol‐1 and of 1, 1‐dimethylcyclohexane on catalytic reduction of 1, 1‐dimethylcyclohexanedione‐3, 5 (dimedone)
Authors: Wibaut J. P. , Gitsels H. P. L.
Published: September 2010

When dimedone is reduced catalytically in 96% ethanol containing 1% hydrogen chloride in solution and with platinum (according to Adams) as a catalyst, there is formed about 58% of the theoretical amount of 3, 3‐dimethylcyclohexanol‐1 and 10% of the theoretical amount of 1, 1‐dimethylcyclohexane.
Die Einwirkung von Aryllithiumverbindungen auf Diarylketone. I. Die Bildung von Triarylcarbinolen
Authors: Faber A. C. , Nauta W. Th.
Published: September 2010

Durch Einwirkung von Aryllithiumverbindungen auf Diarylketone wurde eine Anzahl von methylsubstituierten Tripenylcarbinolen erhalten. Wenn im Diarylketon mehr als zwei Orthomethylgruppen vorhanden sind, findet keine Carbinolbildung statt. An deren Stelle wurden in einigen Fällen Stoffe erhalten, denen vermutlich die Struktur eines methylsubstituierten 9,10‐Diaryl‐9,10‐dioxy‐9,10‐dihydro‐phenanthrens oder ‐anthracens zuerkannt werden muss.
Synthesis of glycerides with the aid of trityl compounds. V. Triacid glycerides with a low‐melting component acid
Authors: Verkade P. E.
Published: September 2010

The preparation of the three butyryl‐palmityl‐stearyl glycerols and of the three oleyl‐palmityl‐stearyl glycerols is described.
Deacylation of aromatic acylamino compounds having a nitro group in the ortho or para position. Steric hindrance of resonance
Authors: Witjens P. H. , Wepster B. M. , Verkade P. E.
Published: September 2010

The work on the deacylation of aromatic acylamino compounds having a nitro group in the ortho or para position, in alcoholic medium under the influence of sodium alcoholate as a catalyst was continued. In this reaction the ‐E‐effect of the nitro group, the tendency toward electromerization of the o‐ or p‐nitrophenylamino grouping plays a predominant part. Typical cases of steric hindrance of resonance could consequently be ascertained with the help of this reaction.
Transformations “Ordre‐Désordre” dans les Réseaux Cristallins de Molécules Organiques, I. Propriétés physiques des molécules du Cα4, spécialement de C(SCH3)4
Authors: Backer H. J. , Perdok W. G.
Published: September 2010

Le composé C(SCH3)4 a été étudié comme typique de molécule sphérique du type Cα4.

Ćette substance présente un point de fusion élevé (65.5°), une cristallisation facile, une grande volatilité et une odeur camphrée.

Elle se présente sous trois formes; deux sont tétragonales et la troisième, stable jusqu'au point de fusion, est cubique (cristaux plastiques). L'abasissement moléculaire du point de fusion est de 38° et l'entropie moléculaire de fusion n'est que de 3.6 cal/degré. A l'aide d'une courbe d'échauffement, on établit les points de transformation à 23.2, 45.5 et 65.5°. Les mesures thermiques donnent pour les chaleurs spécifiques des différente formes: I 0.21, II 0.23, III 0.31, liquide 0.34 cal/g/degré et pour les chaleurs moléculaires de transformation: Q1 146, Q2 1820, Q3990 cal. La phase cubique forme des cristaux mixtes avec le naphtalène.

En déterminat la densité l'indice de réfraction et la constante diélectrique, on trouve le moment dipolaire μ = 0.50. La mesure de la réfraction moléculaire (RD = 57.21) nous met en état de fixer exactement la réfraction atomique du soufre dans les sulfures organiques (SD = 7.98). La tension superficielle à 70° est σ = 36 dynes/cm et le parachor = 419. Les propriétés spéciales de la phase cubique de C(SCH3)4 ne sont pas dues à une rotation des groupes SCH3 (examen Röntgenographique) ou des molécules entières (manque d'espace), mais à une orientaion désordonnée des molécules.
Sur la Quantité de Matière Cristallisée dans la Cellulose Régénérée: (Communication préliminaire)
Authors: Hermans P. H.
Published: September 2010

En opérant sur des fils‐modèles de cellulose régénérée d'orientation croissante, on a déduit du diagramme de diffraction de rayons X le degré d'orientation de leur partie cristallisée.

En admettant que la biréfringence spécifique de la fibre de ramie est très voisine de celle de la cellulose cristallisée, on peut calculer la biréfringence que présenteraient ces fils, s'ils étaient entiérement composés de matière cristalline. La biréfringence observée étant sensiblement plus faible, il s'ensuit que les fils ne contiennent qu'une certaine fraction de matière cristallisée à côté d'une partie considérable de matière “amorphe”, qui du reste, contribue également à la biréfringence totale. Les données expérimentales ne permettent pas d'en déduire la quantité de la partie cristalline, mais seulement de fixer sa limite supérieure. D'une extrapolation vers l'orientation zéro on peut déduire que, pour l'état isotrope des objets étudiés, cette limite est de 20‐30 % environ. Si l'on admet avec M. Kratky que la quantité de matière cristallisée reste constante pendant la déformation, elle serait done au maximum du même ordre de grandeur pour les fils orientés.

Il y a lieu de remarquer que si l'on considère les propriétés optiques de la cellulose comme celles d'un corps mixte binaire, d'après Wiener, les deux composants sont anisotropes.
Untersuchungen über Pilzfarbstoffe XVI: Synthetische Versuche zur Konstitutionsaufklärung des Phomazarins (III).
Authors: KÖgl F. , van Wessem G. C. , Elsbach O. I.
Published: September 2010

Es wurde versucht, die Konstitution der durch oxydativen Abbau von Phomazarin‐(‐triacetat) erhaltenen Oxy‐methoxy‐n‐butyl‐phthalsäure auf synthetischem Wege zu beweisen. Da die Synthese dieses 5‐fach substituierten Benzenderivats auf Schwierigkeiten stiess, wurde die analytische Säure decarboxyliert und das Reaktionsprodukt mit synthetisch gewonnenem 3‐Methoxy‐4‐n‐butyl‐phenol identifiziert. Hierdurch sind die in der vorhergehenden Mitteilung für Phomazarin in Betracht gezogenen Formeln auch hinsichtlich Ring A bewiesen.
Presence of nicotinic acid (free and combined) in blood
Authors: Niemeyer J. A.
Published: September 2010

As the nicotinic acid level in urine seems to show no typical changes in the case of nicotinic acid deficiency, investigation of the amount of it in blood was attempted. The various methods give various results, and it is considered that a different technique is desirable, in which a distinction is made between the nicotinic acid which is free in the filtrate and that which is combined with the proteins when the blood is deproteinized. Nicotinic acid added to blood is found entirely as free nicotinic acid. Using a test curve in the colorimetric König reaction is not advisable, moreover it is possible to avoid its use, as was the case in this investigation.
A study on the adsorption of normal, branched and unsaturated fatty acids and related compounds by means of adsorption analysis
Authors: Claesson Stig
Published: September 2010

It has been shown that with a special type of silica as adsorbent all unbranched saturated fatty acids are adsorbed to the same amount from non‐polar solvents, independent of the length of the carbon chain. Branched fatty acids are adsorbed less and unsaturated more. The same rules are valid for the methyl esters of the fatty acids. It has also been shown that this phenomenon can be utilized for analytical purposes both by means of frontal analysis and displacement development. By the latter method it is possible to make a quantitative separation of a mixture of fatty acids into groups containing branched, normal and unsaturated compounds, respectively, which thereafter can be analysed for compounds with differing lengths of the carbon chain, with activated carbon as adsorbent. The adsorption of some other compounds have also been investigated using silica as adsorbent.
Researches on heat of combustion II: Internal lag and method of stirring in isothermally jacketed calorimeters
Authors: Coops J. , van Nes K.
Published: September 2010

After a discussion of the requirements to be met by the method of stirring used in liquid calorimeters for accurate heat measurements, a description is given of a calorimeter constructed on a new principle. The development of heat occurs in a cylinder which is somewhat smaller than the calorimeter vessel. Water is circulated between the two walls, where the thermometer is placed by means of a centrally fixed centrifugal pump. In this way, the actual wall temperature of the calorimeter‐vessel is measured; this is essential for the accurate calculation of the “radiation” correction. A simple method is described for determining the heat due to stirring. Finally, the required minimum duration of the main period is discussed.