bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Indicators for Different Pineapple Cultivars Compared with the Current Standard ‘Smooth Cayenne’ in West Africa and Reunion Island: A First Step toward Modeling Growth
Authors: Fournier Patrick , Dubois Cécile , Benneveau Aurore , Soler Alain
Published: November 2010

European markets are segmented with several pineapple [Ananas comosus (L.) Merr.] cultivars, the ‘Smooth Cayenne’ (SC), the ‘MD‐2’ hybrid, the new standard, ‘Queen’ and the ‘Flhoran 41’ (a red shell Cirad hybrid). Growth indicator standards are based on SC but growth characteristics may differ between cultivars. To determine if growth characteristics are comparable among pineapple cultivars, we analyzed the vegetative growths of SC, MD‐2, Flhoran 41, and Queen Victoria in Ivory Coast and Reunion Island. First, the vegetative growths of plants produced from stem suckers were monitored using three indicators, the number of leaves, the D leaf weight and the plant weight. Then, the growths of plants produced from different types of planting material of Flhoran 41 were compared. Finally, the seasonal variations of Queen Victoria growth were analyzed to establish the basis of a heat unit model of growth for pineapple. All cultivars showed similar growth patterns but with some specificities. Plant weight increases were higher for MD‐2 and Flhoran 41. At forcing, the D leaf weight was significantly lower in Flhoran 41 but the plants had a greater number of leaves resulting in similar plant weights. As already observed in SC, Flhoran 41 stem suckers grew faster than slips and crowns. Finally, the plant weight increase in Queen Victoria was highly correlated with the sum of temperatures. These observations allowed us to establish the basis of a heat unit model of pineapple growth based on sum of temperatures.
Nitrogen Rate, Landscape Position, and Harvesting of Corn Stover Impacts on Energy Gains and Sustainability of Corn Production Systems in South Dakota
Authors: Mamani‐Pati F. , Clay D. E. , Carlson C. G. , Clay S. A. , Reicks G. , Kim K.
Published: November 2010

The harvesting of plant biomass in excess of the soil organic carbon (SOC) maintenance requirement can produce short‐term economic benefits at the cost of long‐term sustainability. The objective of this study was to assess the impact of corn (Zea mays L.) harvesting approach, N rate, and simulated landscape positions on estimated long‐term SOC maintenance, profitability, and the energy efficiency of no‐till corn grown in eastern South Dakota. The 3‐yr experiment (2002–2004) contained four N rates (0, 56, 112, and 168 kg N ha−1), two simulated landscape positions (shoulder and backslope), and two harvesting methods (grain with 100% stover returned or grain + 40% corn stover returned). No‐tillage was used at the site. Energy gains (out – input), for a cropping system where corn grain or corn grain plus stover was sold for ethanol production, were calculated. Profitability was estimated and SOC turnover was simulated using the annual time‐step model, SOCt = SOCt‐1 + kNHCNHC – ksoc SOCt‐1, where SOCt was SOC at time t, SOCt‐1 was SOC at the sampling date before time t, kNHC was rate that nonharvested carbon (NHC) was converted to SOC, and ksoc was the rate that SOC was converted to CO2. Tillage impacts on kSOC was estimated with the model ksoc [g SOC‐C (g SOC year)−1] = 0.0115 + 0.00631(tillage events). When only grain was harvested, the highest and lowest energy gains and financial were associated with the 112 kg N ha−1 (46.6 GJ ha−1 and $427 ha−1) and the 0 kg N per ha−1 (37.5 GJ ha−1 and $192 ha−1) treatments, respectively. Applying more than 112 kg N ha−1 did not increase energy gains or financial returns. Profits were increased by 60% when corn stover was harvested for ethanol production and lower yielding simulated shoulder/summit position had a lower energy gain (59.3 GJ ha−1 and $425 ha−1) and financial return than the backslope position (66.3 GJ ha−1 and $614 ha−1). The SOC sustainability analysis suggests that the ability of a system to maintain SOC depends on many factors including the amount of nonharvested carbon returned to the site, and the amount of carbon contained in the soil.
Alfalfa Yield and Morphology of Three Fall‐Dormancy Categories Harvested at Two Phenological Stages in a Subtropical Climate
Authors: Rimi Filippo , Macolino Stefano , Leinauer Bernd , Lauriault Leonard M. , Ziliotto Umberto
Published: November 2010

Alfalfa (Medicago sativa L.) is the most important hay crop used in the dairy industry of the Po Valley, Italy, characterized by a subtropical climate with hot, humid summers and cool winters. Information is lacking as to selecting fall dormancy (FD) varieties adapted to the region and their response to intense harvest regimes. A 3‐yr study was conducted to investigate the effect of two harvest regimes based on phenological stage (early bud and early flower) and three FD categories on productivity, canopy height, and leaf to stem proportion. Cultivars with FD ratings of 7.5 (less nondormant), 8.5 (nondormant), and 10.5 (very nondormant) were seeded in April 2005 at the experimental farm of Padova University in Legnaro, Italy. The experimental design was a randomized complete block in a split‐plot arrangement. Canopy height and dry matter (DM) yield were measured at each harvest. Subsamples were collected to determine leaf area index (LAI), stem silhouette area index (SAI), and leaf dry matter to stem dry matter ratios (LSR). Nondormant cultivars had higher DM yield (18.2 Mg ha−1) than less nondormant (17.1 Mg ha−1) and very nondormant cultivars (16.9 Mg ha−1). Harvesting at early bud decreased DM yield by 11% compared to early flower. The FD categories had no effect on LAI/SAI and LSR ratios, however harvesting at early bud increased both ratios by 12.0 to 12.5%. Producers in subtropical climates may obtain alfalfa hay with a high portion of leaves at a reasonable yield from the three tested FD categories by cutting alfalfa at early bud stage.
Crop Response following Tall Fescue Sod and Agronomic Crops
Authors: Drake W. L. , Jordan D. L. , Schroeder‐Moreno M. , Johnson P. D. , Heitman J. L. , Cardoza Y. J. , Brandenburg R. L. , Shew B. B. , Corbett T. , Bogle C. R. , Ye W. , Hardy D.
Published: November 2010

Sod‐based production systems have been successful in the southeastern and mid‐Atlantic regions of the United States as an alternative to conventional tillage systems. However, research comparing these systems in North Carolina is limited. Therefore, research was conducted at four locations in North Carolina to compare corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea L.), and soybean [Glycine max (L.) Merr.] yield when these crops were strip tilled following 4 yr of continuous tall fescue (Shedonorus phoenix Scop.) vs. 4 yr of either corn or cotton grown in no tillage or strip tillage. Cotton yield was higher following tall fescue compared with yield following agronomic crops. In contrast, yield of corn was lower following tall fescue compared with agronomic crops while peanut and soybean yields were not affected by previous cropping history. Additional treatments in peanut included conventional tillage following both cropping systems, and pod yield was lower when peanut was strip tilled into either tall fescue or residue from corn or cotton compared with conventional tillage systems. No major differences in soil bulk density at depths of 0 to 8 cm or 8 to 16 cm were noted when comparing tall fescue or agronomic crops either in strip tillage or nontilled zones. Populations of soil parasitic nematodes were often lower in peanut following tall fescue than when following agronomic crops. These experiments indicate that sod‐based systems may be an effective alternative to reduced tillage systems, especially for cotton. However, yield benefits were not observed for peanut or soybean and corn was negatively affected by tall fescue.
Unique Dairy Applications of Eastern Gamagrass Forages in Central Wisconsin: I. Yield Potential
Authors: Coblentz Wayne K. , Jokela William E. , Hoffman Patrick C. , Bertram Michael G.
Published: November 2010

Replacement dairy heifers (Bos taurus) offered diets comprised largely of corn (Zea mays L.) silage or other high‐energy forages often become overconditioned, which may damage their future performance as lactating cows. Our objective was to assess the yield potential of a perennial C4 grass, eastern gamagrass [Tripsacum dactyloides (L.) L.], for incorporation into fiber‐demanding, dairy‐heifer or dry‐cow diets. Replicated field plots of ‘Pete’ eastern gamagrass were evaluated within nine harvest systems and four N fertilization regimes. For single‐harvest systems, dry matter (DM) yields increased across harvest dates, reaching numerical maximums of 7192, 9764, and 7554 kg ha−1 by mid‐August of 2007, 2008, and 2009, respectively. During each year, there was a strong linear (P < 0.001) effect of harvest date; however, higher‐ordered effects varied within year. Relatively large yield increases (≥1812 kg ha−1) between early and mid‐August during 2008 and 2009 suggest that better yields could be achieved by delaying single harvests of eastern gamagrass beyond mid‐August. Yields of DM from double‐harvest systems were not competitive with single‐harvest systems timed in mid‐August. Nitrogen fertilization increased (P < 0.001) DM yields, exhibiting both linear (P < 0.001) and quadratic (P = 0.027) effects of application rate. However, efficiency of N usage was reduced as fertilization rates increased.
Retrospective respiratory triggering renal perfusion MRI
Authors: Attenberger Ulrike I. , Sourbron Steven P. , Michaely Henrik J. , Reiser Maximilian F. , Schoenberg Stefan O.
Published: November 2010

Background: Artifacts of respiratory motion are one of the well-known limitations of dynamic contrast-enhanced MRI (DCE-MRI) of the kidney.

Purpose: To propose and evaluate a retrospective triggering approach to minimize the effect of respiratory motion in DCE-MRI of the kidney.

Material and Methods: Nine consecutive patients underwent renal perfusion measurements. Data were acquired with a 2D saturation-recovery TurboFLASH sequence. In order to test the dependence of the results on size and location of the manually drawn triggering regions of interest (ROIs), three widely differing triggering regions were defined by one observer. Mean value, standard deviation, and variability of the renal function parameters plasma flow (FP), plasma volume (VP), plasma transit time (TP), tubular flow (FT), tubular volume (VT), and tubular transit time (TT) were calculated on a per-patient basis.

Results: The results show that triggered data have adequate temporal resolution to measure blood flow. The overall average values of the function parameters were: 152.77 (FP), 15.18 (VP), 6,73 (TP), 18.50 (FT), 35.36 (VT), and 117.67 (TT). The variability (calculated in % SD from the mean value) for three different respiratory triggering regions defined on a per-patient basis was between 0.81% and 9.87% for FP, 1.45% and 8.19% for VP, 0% and 9.63% for TP, 2.15% and 12.23% for TF, 0.8% and 17.28% for VT, and 1.97% and 12.87% for TT.

Conclusion: Triggering reduces the oscillations in the signal curves and produces sharper parametric maps. In contrast to numerically challenging approaches like registration and segmentation it can be applied in clinical routine, but a (semi)-automatic approach to select the triggering ROI is desirable to reduce user dependence.
Is the location of the Wrisberg ligament related to frequent complete discoid lateral meniscus tear?
Authors: Kim Ji-Eun , Choi Sang-Hee
Published: November 2010

Background: A discoid lateral meniscus is a relatively common anatomic variant in Korean and Japanese subjects that presents with snapping knee syndrome.

Purpose: To evaluate the relationship between the location of the Wrisberg ligament and the frequency of lateral meniscus tear in patients with complete discoid lateral meniscus.

Material and Methods: A total of 109 consecutive patients with arthroscopically proven complete discoid lateral menisci and another 100 patients with non-discoid lateral menisci were evaluated retrospectively. We reviewed the MR images to determine the attachment level of the Wrisberg ligament on the medial femoral condyle, the thickness of the Wrisberg ligament, and the presence and type of lateral meniscus tear. The relationship between the frequency of lateral meniscus tear according to the attachment level on the medial femoral condyle and the thickness of the Wrisberg ligament on both groups was analyzed.

Results: Among them, 153 patients had Wrisberg ligament, 76 patients had complete lateral discoid menisci, and 77 patients had non-discoid lateral menisci. Lateral meniscus tears were found in 115 patients; 83 tears were in the Wrisberg ligament group ( n=153) and 32 tears were in the non-Wrisberg ligament group ( n =56). The presence of Wrisberg ligament alone was not significantly related to lateral meniscus tear ( P=0.755). Among 83 lateral meniscus tears in the Wrisberg ligament group, 58 were identified in complete discoid lateral meniscus with high-riding Wrisberg ligament. The frequency of a lateral meniscus tear was lower in patients with low-riding Wrisberg ligament on complete discoid lateral meniscus ( P = 0.020).

Conclusion: In patients with complete discoid lateral meniscus, lateral meniscus tear is seen less often with low- than high-riding Wrisberg ligament.
Neuroprotective Properties of Mildronate, a Small Molecule, in a Rat Model of Parkinson’s Disease
Authors: Klusa Vija Z. , Isajevs Sergejs , Svirina Darja , Pupure Jolanta , Beitnere Ulrika , Rumaks Juris , Svirskis Simons , Jansone Baiba , Dzirkale Zane , Muceniece Ruta , Kalvinsh Ivars , Vinters Harry V.
Published: November 2010

Previously, we have found that mildronate [3-(2,2,2-trimethylhydrazinium) propionate dihydrate], a small molecule with charged nitrogen and oxygen atoms, protects mitochondrial metabolism that is altered by inhibitors of complex I and has neuroprotective effects in an azidothymidine-neurotoxicity mouse model. In the present study, we investigated the effects of mildronate in a rat model of Parkinson’s disease (PD) that was generated via a unilateral intrastriatal injection of the neurotoxin 6-hydroxydopamine (6‑OHDA). We assessed the expression of cell biomarkers that are involved in signaling cascades and provide neural and glial integration: the neuronal marker TH (tyrosine hydroxylase); ubiquitin (a regulatory peptide involved in the ubiquitin-proteasome degradation system); Notch-3 (a marker of progenitor cells); IBA-1 (a marker of microglial cells); glial fibrillary acidic protein, GFAP (a marker of astrocytes); and inducible nitric oxide synthase, iNOS (a marker of inflammation). The data show that in the 6-OHDA-lesioned striatum, mildronate completely prevented the loss of TH, stimulated Notch-3 expression and decreased the expression of ubiquitin, GFAP and iNOS. These results provide evidence for the ability of mildronate to control the expression of an array of cellular proteins and, thus, impart multi-faceted homeostatic mechanisms in neurons and glial cells in a rat model of PD. We suggest that the use of mildronate provides a protective effect during the early stages of PD that can delay or halt the progression of this neurodegenerative disease.
Goniometer Crosstalk Compensation for Knee Joint Applications
Authors: Sato Tatiana de Oliveira , Hansson Gert-Åke , Coury Helenice Jane Cote Gil
Published: November 2010

Electrogoniometers are prone to crosstalk errors related to endblocks rotation (general crosstalk) and to the characteristics of each sensor (individual crosstalk). The aim of this study was to assess the crosstalk errors due to endblock misalignments and to propose a procedure to compensate for these errors in knee applications. A precision jig was used to simulate pure ±100° flexion/extension movements. A goniometer was mounted with various degrees of valgus/varus (±20°) and rotation (±30°) misalignments. For valgus/varus misalignments, although offset compensation eliminated the error in the valgus/varus recordings for 0° of flexion/extension and reduced it to a few degrees for small (±30°) flexion/extension angles (root mean square error = 1.1°), the individual crosstalk caused pronounced errors for large (±100°) angles (18.8°). Subsequent compensation for this crosstalk reduced these errors to 0.8° and 4.5°, respectively. For rotational misalignment, compensation for the general crosstalk by means of coordinate system rotation, in combination with compensation for the individual crosstalk, reduced the errors for small (±30°) and large (±100°) flexion/extension angles from 3.6° to 0.5° and from 15.5° to 2.4°, respectively. Crosstalk errors were efficiently compensated by the procedures applied, which might be useful in preprocessing of knee functional data, thereby substantially improving goniometer accuracy.
A Novel Acoustic Sensor Approach to Classify Seeds Based on Sound Absorption Spectra
Authors: Gasso-Tortajada Vicent , Ward Alastair J. , Mansur Hasib , Brøchner Torben , Sørensen Claus G. , Green Ole
Published: November 2010

A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA), was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA) method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials.
Non-Destructive Optical Monitoring of Grape Maturation by Proximal Sensing
Authors: Ghozlen Naïma Ben , Cerovic Zoran G. , Germain Claire , Toutain Sandrine , Latouche Gwendal
Published: November 2010

A new, commercial, fluorescence-based optical sensor for plant constituent assessment was recently introduced. This sensor, called the Multiplex® (FORCE-A, Orsay, France), was used to monitor grape maturation by specifically monitoring anthocyanin accumulation. We derived the empirical anthocyanin content calibration curves for Champagne red grape cultivars, and we also propose a general model for the influence of the proportion of red berries, skin anthocyanin content and berry size on Multiplex® indices. The Multiplex® was used on both berry samples in the laboratory and on intact clusters in the vineyard. We found that the inverted and log-transformed far-red fluorescence signal called the FERARI index, although sensitive to sample size and distance, is potentially the most widely applicable. The more robust indices, based on chlorophyll fluorescence excitation ratios, showed three ranges of dependence on anthocyanin content. We found that up to 0.16 mg cm−2, equivalent to approximately 0.6 mg g−1, all indices increase with accumulation of skin anthocyanin content. Excitation ratio-based indices decrease with anthocyanin accumulation beyond 0.27 mg cm−2. We showed that the Multiplex® can be advantageously used in vineyards on intact clusters for the non-destructive assessment of anthocyanin content of vine blocks and can now be tested on other fruits and vegetables based on the same model.
A Method for Evaluating Dynamical Friction in Linear Ball Bearings
Authors: Fujii Yusaku , Maru Koichi , Jin Tao , Yupapin Preecha P. , Mitatha Somsak
Published: November 2010

A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To evaluate the acceleration of its centre of gravity, the acceleration of two different points on it is measured using a dual-axis optical interferometer.
Transcranial Magnetic Stimulation and Volitional Quadriceps Activation
Authors: Gibbons Christopher E. , Pietrosimone Brian G. , Hart Joseph M. , Saliba Susan A. , Ingersoll Christopher D.
Published: November 2010

Context:

Quadriceps-activation deficits have been reported after meniscectomy. Transcranial magnetic stimulation (TMS) in conjunction with maximal contractions affects quadriceps activation in patients after meniscectomy.

Objective:

To determine the effect of single-pulsed TMS on quadriceps central activation ratio (CAR) in patients after meniscectomy.

Design:

Randomized controlled clinical trial.

Setting:

University laboratory.

Patients or Other Participants:

Twenty participants who had partial meniscectomy and who had a CAR less than 85% were assigned randomly to the TMS group (7 men, 4 women; age  =  38.1 ± 16.2 years, height  =  176.8 ± 11.5 cm, mass  =  91.8 ± 27.5 kg, postoperative time  =  36.7 ± 34.9 weeks) or the control group (7 men, 2 women; age  =  38.2 ± 17.5 years, height  =  176.5 ± 7.9 cm, mass  =  86.2 ± 15.3 kg, postoperative time  =  36.6 ± 37.4 weeks).

Intervention(s):

Participants in the experimental group received TMS over the motor cortex that was contralateral to the involved leg and performed 3 maximal quadriceps contractions with the involved leg. The control group performed 3 maximal quadriceps contractions without the TMS.

Main Outcome Measure(s):

Quadriceps activation was assessed using the CAR, which was measured in 70° of knee flexion at baseline and at 0, 10, 30, and 60 minutes posttest. The CAR was expressed as a percentage of full activation.

Results:

Differences in CAR were detected over time (F4,72  =  3.025, P  = .02). No interaction (F4,72  =  1.457, P  =  .22) or between-groups differences (F1,18  =  0.096, P  =  .76) were found for CAR. Moderate CAR effect sizes were found at 10 (Cohen d  =  0.54, 95% confidence interval [CI]  =  −0.33, 1.37) and 60 (Cohen d  =  0.50, 95% CI  =  −0.37, 1.33) minutes in the TMS group compared with CAR at baseline. Strong effect sizes were found for CAR at 10 (Cohen d  =  0.82, 95% CI  =  −0.13, 1.7) and 60 (Cohen d  =  1.06, 95% CI  =  0.08, 1.95) minutes in the TMS group when comparing percentage change scores between groups.

Conclusions:

No differences in CAR were found between groups at selected points within a 60-minute time frame, yet moderate to strong effect sizes for CAR were found at 10 and 60 minutes in the TMS group, indicating increased activation after TMS.
The Manufacture of Resorbable Suture Material from Magnesium
Authors: Seitz Jan‐Marten , Wulf Eric , Freytag Patrik , Bormann Dirk , Bach Friedrich‐Wilhelm
Published: November 2010

Magnesium alloys present an alternative to medical cases in which polymeric sutures may not be ideal. To date, no efficient and low‐cost manufacturing process for the fabrication of magnesium‐based sutures can be found. To obtain an alternative, the previously characterised magnesium alloys ZEK100 (98% Mg), AX30 (96.2% Mg), AL36 (91% Mg) and MgCa0.8 (99.2% Mg) were cast, extruded into 30 mm diameter bars and extruded into 0.5 mm diameter wires. To determine the mechanical properties of the wires, grain size measurements, tensile tests as well as qualitative bending tests were carried out. The ZEK100 alloy's wires showed the finest microstructure having grains of 1.2 µm in diameter. Coarser microstructures were observed for MgCa0.8, AX30 and AL36. The alloy ZEK100 had the highest tensile stress (367 MPa) also revealing a brittle behaviour due to its fine microstructure. The tensile test, carried out for AX30 as well as AL36, resulted in comparable high fracture strains (10.6%) and tensile stresses (300 MPa). However, MgCa0.8 showed a tensile strength of 315 MPa and a low strain of 1.6%. Within the qualitative bending test wires made of the alloy AL36 were able to form tight knots, which is a key feature for suture applications. The comparison of the magnesium sutures with commercially available polymeric sutures revealed lower strength and elongation for the magnesium alloys. Yet, the wires exhibited mechanical properties that can meet the requirements of a suture material.
Bioactive Ti Metal and its Alloys Prepared by Chemical Treatments: State‐of‐the‐Art and Future Trends
Authors: Kokubo Tadashi , Yamaguchi Seiji
Published: November 2010

Titanium metal and its alloys are widely used as various implants in orthopaedic and dental fields, because of their good biocompatibility and high mechanical strength. However, they do not bond to living bone. Here, we review the literature showing that they will spontaneously bond tightly to living bone, if they are treated with an acid or alkaline solution and then subjected to heat treatment. This occurs due to the materials becoming negatively or positively charged on their surfaces in the bodily environment, which induces apatite deposition. Porous Ti metal subjected to such treatment exhibits not only osteoconductivity but also osteoinductivity. Examples and clinical applications are reviewed.
Correlation Between Surface Chemistry and Electrocatalytic Properties of Monodisperse PtxNi1‐x Nanoparticles
Authors: Wang Chao , Chi Miaofang , Wang Guofeng , van der Vliet Dennis , Li Dongguo , More Karren , Wang Hsien‐Hau , Schlueter John A. , Markovic Nenad M. , Stamenkovic Vojislav R.
Published: November 2010

Monodisperse and homogeneous PtxNi1‐x alloy nanoparticles of various compositions are synthesized via an organic solution approach in order to reveal the correlation between surface chemistry and their electrocatalytic properties. Atomic‐level microscopic analysis of the compositional profile and modeling of nanoparticle structure are combined to follow the dependence of Ni dissolution on the initial alloy composition and formation of the Pt‐skeleton nanostructures. The developed approach and acquired knowledge about surface structure‐property correlation can be further generalized and applied towards the design of advanced functional nanomaterials.
Simultaneous Reduction and Surface Functionalization of Graphene Oxide by Mussel‐Inspired Chemistry
Authors: Kang Sung Min , Park Sungjin , Kim Daewon , Park Sung Young , Ruoff Rodney S. , Lee Haeshin
Published: November 2010

This study presents a method of simultaneous reduction and surface functionalization of graphene oxide by a one‐step poly(norepinephrine) functionalization. The pH‐induced aqueous functionalization of graphene oxide by poly(norepinephrine), a catecholamine polymer inspired by the robust adhesion of marine mussels, chemically reduced and functionalized graphene oxide. Moreover, the polymerized norepinephrine (pNor) layer provided multifunctionality on the reduced graphene oxide that includes surface‐initiated polymerization and spontaneous metallic nanoparticle formation. This facile surface modification strategy can be a useful platform for graphene‐based nano‐composites.
Constrained receding‐horizon experiment design and parameter estimation in the presence of poor initial conditions
Authors: Zhu Yijia , Huang Biao
Published: November 2010

An optimal experiment design assumes the existence of an initial or nominal process model. The efficiency of this procedure depends on how the initial model is chosen. This creates a practical dilemma as estimating the model is precisely what the experiment tries to achieve. A novel approach to experiment design for identification of nonlinear systems is developed, with the purpose of reducing the influence of poor initial values. The experiment design and the parameter estimation are conducted iteratively under a receding‐horizon framework. By taking steady‐state prior knowledge into account, constraints on the parameters can be derived. Such constraints help reduce influence of poor initial models. The proposed algorithm is illustrated through examples to demonstrate its efficiency. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Preparation and properties of core–shell nanosilica/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) latex
Authors: Wei Zheng , Ling He , Junyan Liang , Gang Chang , Na Wang
Published: November 2010

A core–shell nanosilica (nano‐SiO2)/fluorinated acrylic copolymer latex, where nano‐SiO2 served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2‐trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano‐SiO2. The morphology and particle size of the nano‐SiO2/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano‐SiO2/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano‐SiO2/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano‐SiO2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Optimizing the step‐by‐step forming processes for fabricating a poly(DL‐lactic‐co‐glycolic acid)‐sandwiched cell/hydrogel construct
Authors: Wang Xiaohong , Sui Shaochun , Liu Chang
Published: November 2010

A poly(DL‐lactic‐co‐glycolic acid) (PLGA)‐sandwiched cell/fibrin construct was fabricated to overcome the weak mechanical properties of cell/hydrogel mixtures. This construct was formed with a step‐by‐step mold/extraction method to generate a middle smooth muscle layer of natural blood vessels. A desired three‐layer construct, as an integrated entity with optimized inner structures, was achieved by the control of the size of the molds, the concentration of the polymer systems, and the temperature of the extraction and polymerization processes. The constructs were fabricated with the following dimensions: length = 10–25 mm, diameter >2 mm, and wall thickness = 0.6–2 mm. Different microstructures in different layers of the sandwiched structure resulted in different functions. The pore structure in the inner PLGA and middle fibrin layers was beneficial for nutrient transference, whereas the solid structure without pores in the outmost surface of the outer PLGA layer could prevent fluid from leaking during in vitro culturing and in vivo implantation. This study showed that this can be a promising approach for the fabrication of synthetic‐polymer‐sandwiched viable cell/hydrogel constructs for wide potential application in complex organ manufacturing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Electronic Transfer and Phase Transitions in Cationic Intercalation Chemistry in Low‐Dimensional Chalcogenides
Authors: Rouxel Jean
Published: November 2010

Besides their striking physical properties, low‐dimensional solids have also a very rich chemical reactivity, of which the redox intercalation‐disintercalation processes represent an essential part. The intercalation of cations is the result of a coupled ion‐electron transfer reaction. The geometrical features associated to the ions are well known at present. However the role of the electron is oftentime restricted to a modification of the physical properties of the host structure. In this contribution it will be shown that the electronic transfer plays an essential role concerning the ability to intercalate and, also, largely governs the phase transitions that can be observed. Such phase transitions concern either the position taken by the intercalated cations or the host framework itself. They can be also related to a strong ion‐electron coupling.
Schichtkristalle Bi2Te3 und Sb2Te3 — Punktdefekte, Bindungspolarität und einige Transporteigenschaften
Authors: Stary Z. , Horak J.
Published: November 2010

The present paper deals with the determination of changes in bond polarity of Sb2‐xBixTe3 mixed crystals as a function of composition. In addition, the relation between the bond polarization and the concentration of antisite defects is investigated. A model is proposed, in order to evaluate the concentration of Sb'Te and Bi'Te antisite defects in terms of the composition variable x. Consequences for the design of p‐n‐junctions are indicated.
The Correlation Between Diffusion Behaviour and Phonon Softening in BCC Metals
Authors: Herzig Chr.
Published: November 2010

A new approach is proposed to explain the wide spread of self diffusion behaviour and the curvature of the Arrhenius plots in bcc metals by typical diffusion‐relevant low‐energy phonon modes. In bcc transition metals the activation enthalpy and the energy of the LA 2/3 (111) phonon mode decrease systematically with decreasing d‐electron concentration, while the diffusivity and the degree of curvature increase. The migration enthalpy HM is related to the frequency of this mode, i.e. to the amplitude of atomic displacements in the 〈111〉 nearest neighbour jump direction. On the basis of experimental results a good correlation between the square of this phonon frequency and the activation enthalpy is obtained. The curvatures of the Arrhenius plots are explained by a decrease of HM with decreasing temperature due to the temperature dependence of the soft T1A 1/2 〈110〉 mode, which causes a “breathing” motion of the saddle point atoms. Thus the model of phonon‐assisted diffusion jumps via monovacancies yields a uniform explanation for the main features of diffusion in bcc metals.
Organische Festkörper. Anwendungsmöglichkeiten in der Optik und Elektronik
Authors: Sixl H.
Published: November 2010

Some fundamental aspects of basic principles and applications of organic solids will be presented in this lecture. A special focus is given on present optoelectronic research activities at Hoechst AG related to physico‐chemical and physico‐technical material research. The first part is concerned with the actual research on polymer optical fibers. The second part is concerned with basic principles and properties of non‐linear optical devices. Finally the third part refers to the fundamentals of electrical conducting polymers.
Demixing in Trivalent Doped Transition Metal Oxides Exposed to an Oxygen Potential Gradient
Authors: Martin M. , Schmackpfeffer R.
Published: November 2010

A formal treatment is given for demixing in a trivalent doped transition metal oxide which is exposed to a stationary oxygen potential gradient. Various disorder types are discussed for the doped oxide, and an analysis is given of the influence of solute‐vacancy interaction on the demixing behavior. The solute can be enriched either at the low or at the high oxygen potential side of the sample depending on the average oxygen potential at which the demixing experiment is carried out and on the strength of the solute‐vacancy interaction.
Zur Hyperfeinstruktur von 111Cd in Metalloxiden
Authors: Bolse W. , Bartos A. , Kesten J. , Lieb K. P. , Uhrmacher M.
Published: November 2010

The Perturbed Angular Correlation method was applied to measure the hyperfine interaction of the 111Cd‐nucleus after implantation of its radioactive mother isotope 111ln (≈ 1012 ions at E ≈ 400 keV) into various metal‐oxides (NiO, CuO, AgO, Cu2O, Ag2O, Al2O3, Cr2O3, In2O3, Rh2O3). In most cases we were able to identify 111Cd on substitutional sites in a defect‐free oxide surrounding by proper thermal annealing of our samples. The capability of the PAC method to resolve small changes in the microsurrounding will be demonstrated by the results of our experiments on In2O3. Exemplary, the application of the technique to the observation of magnetical, structural and chemical phase transitions in NiO, Rh2O3, AgO and CuO will be discussed. By comparing the experimental values with a simple point charge model, a systematic behaviour of the electric field gradients was found.
Methyl Group Quantum Rotation in Various Methyl Group‐IVa Halides, (CH3)4‐nMIVXn with M = Sn, Pb; X = F, Cl, Br
Authors: Prager Michael , Zhang Da , Weiss Alarich
Published: November 2010

Rotational tunnelling and librations of the methyl groups in various methyl group‐IVa halides, (CH3)3SnX, X = F, Cl, Br; (CH3)3PbX, X = Cl; (CH3)2SnX2, X = Br; CH3SnX3, X = Cl, Br have been studied using inelastic neutron scattering (INS) technique. The INS results are discussed with respect to the known crystal structures. All compounds investigated show weak rotational potentials but no systematic trends connected to the chemical composition were observed. The large electronegativity of the halogen atoms and the resulting stronger molecular polarity are taken as the reason for the variety of the crystal structures in these solids and the individual CH3‐group rotational behaviour observed.
Coupled Methyl Quantum Rotation and its Influence on the NMR Spin‐Lattice Relaxation
Authors: van Wüllen L. , Müller‐Warmuth W.
Published: November 2010

1H NMR spin‐lattice relaxation rates T−11 have been measured at 15 and 30 MHz and various temperatures in powdered molecular crystals of (CH3)2SnCl2 and (CH3)2SnCl2 in a (CD3)2SnCl2 matrix. In the second case T−11 can be interpreted in terms of quantum tunnelling as usual, though it cannot be explained by the motion of the CH3 group in a single particle V3 — V6‐potential. In the first case, however, the presence of coupled pairs of rotating methyl groups changes in addition the frequency and temperature dependences of T−11. The results can be explained on the basis of a quantum mechanical treatment of the coupled system, which leads to the occurrence of 4 rotator and 18 magnetic sublevels in the groundstate instead of 2 and 6. Three of the tunnelling transition frequencies are of comparable size, one is substantially smaller and modifies the relaxation rate.
The Diffusion of Li in Poco Graphite and Glassy Carbon at Low Concentrations and High Temperatures
Authors: Jungblut B. , Hoinkis E. , Döbler V. , Meyerheim H. L.
Published: November 2010

X‐ray diffraction and angle dependent X‐ray absorption near edge structure (XANES) measurements were carried out in order to characterize a Poco graphite and a glassy carbon with respect to their long range and short range orders. Poco graphite is a well graphitized polycrystalline material. Glassy carbon has, by contrast, hardly any long range order, but XANES spectra reveal the graphite‐like short range order. The diffusion of 7Li in Poco graphite and in glassy carbon was investigated at Li atomic fractions between 0.1 ppm and 300 ppm and temperatures in the range from 1000 K to 1400 K using a mass spectrometric method. Li was found to be released from Poco graphite mainly via intragranular diffusion and not by Knudsen diffusion through the open interconnected pores. The inaccessible porosity of glassy carbon is equal to the total porosity i.e. open pores are not present. The Arrhenius equations for the diffusion coefficients of Li in Poco graphite and in glassy carbon are D = 3 · 104 · exp(‐2.27 eV/kT) cm2/s and D = 1.5 · 106 · exp(‐3.1 eV/kT) cm2/s.
57Fe‐ und 119Sn‐Mößbauerspektroskopie an gesinterten Eisen‐Zinn‐Pulvermischungen
Authors: Meyer Christian , Nagorny Klaus
Published: November 2010

Iron‐tin powder mixtures in different compositions have been sintered at temperatures of 500°C up to 950°C. The results of 57Fe‐ und 119Sn‐Mößbauer‐measurements of the samples have been compared with the iron‐tin phase diagram. The samples are a mixture of different FeSn‐phases. We have found: α‐Fe, γ‐Fe, β‐Sn, α‐FeSn solid solutions, Fe3Sn, Fe3Sn2, Fe5Sn3 and FeSn. Kinetic measurements have been made to investigate the sintering behaviour of the iron‐tin powders.
In‐situ Mößbauerspectroscopic Investigations of Phase Transformations in Iron Oxide Layers Below Organic Coatings
Authors: Hoffmann K. , Stratmann M.
Published: November 2010

Phase transformations in oxide layers below organic coatings have been investigated by in‐situ Mößbauer spectroscopy. During wetting of preoxidized iron surfaces iron can further corrode without diffusion of O2 through the polymer film. The anodic iron dissolution is compensated by cathodic rust reduction. The reactive rust component γ‐FeOOH can be reduced to the spinel‐phase Fe3 — γO4 changing the rust morphology and causing the loss of adhesion of the organic coating. This reaction is controlled by the ionic conductivity below the organic coating which is caused e.g. by impurities adsorbed from the atmosphere before the application of the organic coating. — In order to retard the redox reactions in oxide scales below organic coatings the oxide surface has been chemically modified e.g. by silanes, phosphates and phosphor‐organic compounds. This decreases the rate of rust reduction significantly.
N‐acetylcysteine modulates doxorubicin‐induced oxidative stress and antioxidant vitamin concentrations in liver of rats
Authors: Koçkar M. Cem , Nazıroğlu Mustafa , Çelik Ömer , Tola H. Tahsin , Bayram Dilek , Koyu Ahmet
Published: November 2010

Doxorubicin (DOX) is a chemotherapeutic agent, and is widely used in cancer treatment. The most common side effect of DOX was indicated on cardiovascular system by experimental studies. There are some studies suggesting oxidative stress‐induced toxic changes on liver related to DOX administration. The aim of the present study was to evaluate whether antioxidant N‐acetylcysteine (NAC) relieves oxidative stress in DOX‐ induced liver injury in rat. Twenty‐four male rats were equally divided into three groups. First group was used as a control. Second group received single dose of DOX. NAC for 10 days was given to constituting the third group after giving one dose of DOX. After 10 days of the experiment, liver tissues were taken from all animals. Lipid peroxidation (LP) levels were higher in the DOX group than in control whereas LP levels were lower in the DOX + NAC group than in control. Vitamin C and vitamin E levels were lower in the DOX group than in control whereas vitamin C and vitamin E levels were higher in the DOX + NAC group than in the DOX group. Reduced glutathione levels were higher in the DOX + NAC group than in control and DOX group. Glutathione peroxidase, vitamin A and β‐carotene values were not changed in the three groups by DOX and NAC administrations. In histopathological evaluation of DOX group, there were mononuclear cell infiltrations, vacuolar degeneration, hepatocytes with basophilic nucleus and sinusoidal dilatations. The findings were totally recovered by NAC administration. In conclusion, N‐acetylcysteine induced modulator effects on the doxorubicin‐induced hepatoxicity by inhibiting free radical production and supporting the antioxidant vitamin levels. Copyright © 2010 John Wiley & Sons, Ltd.
Hydrogen Bonding Versus van der Waals Interactions: Competitive Influence of Noncovalent Interactions on 2D Self‐Assembly at the Liquid–Solid Interface
Authors: Mali Kunal S. , Lava Kathleen , Binnemans Koen , De Feyter Steven
Published: November 2010

The structures of the self‐assembled monolayers of various 4‐alkoxybenzoic acids physisorbed at the liquid–solid interface were established by employing scanning tunnelling microscopy (STM). This study has been essentially undertaken to explore the competitive influence of van der Waals and hydrogen‐bonding interactions on the process of two‐dimensional self‐assembly. These acid derivatives form hydrogen‐bonded dimers as expected; however, the dimers organise themselves in the form of relatively complex lamellae. The characteristic feature of these lamellae is the presence of regular discommensurations or kinks along the lamella propagation direction. The formation of kinked lamellae is discussed in light of the registry mechanism of the alkyl chains with the underlying graphite substrate. The location of the kinks along a lamella depends on the number (odd or even) of carbon atoms in the alkyl chain. This result indicates that concerted van der Waals interactions of the alkyl chain units introduce the odd/even chain‐length effect on the surface‐assembled supramolecular patterns. The odd/even effects are retained even upon complexation with a hydrogen‐bond acceptor. However, as the solvent is changed from 1‐phenyloctane to 1‐octanoic acid, the kinked lamellae as well as the odd/even effects disappear. This solvent‐induced convergence of supramolecular patterns is attained by means of co‐crystallisation of octanoic acid molecules in the 2D crystal lattice, which is evident from high‐resolution STM images. The solvent co‐adsorption phenomenon is discussed in terms of competing van der Waals and hydrogen‐bonding interactions.
Synthesis and Biological Properties of the Cytotoxic 14‐Membered Macrolides Aspergillide A and B
Authors: Díaz‐Oltra Santiago , Angulo‐Pachón César A. , Murga Juan , Falomir Eva , Carda Miguel , Marco J. Alberto
Published: November 2010

Total, stereoselective syntheses of the naturally occurring, cytotoxic macrolides aspergillide A and B are described. Olefin metatheses and asymmetric allylations were key steps in the synthetic sequences. Cytotoxicity assays against several tumor cell lines have been performed for the two aspergillides and some of the intermediates or side products of the synthetic sequence. One of these intermediates has been found markedly active against the human leukemia cancer cell line HL‐60, with an IC50 value comparable with that of the clinical drug fludarabine.
Photocontrollable Analyte‐Responsive Fluorescent Probes: A Photocaged Copper‐Responsive Fluorescence Turn‐On Probe
Authors: Yuan Lin , Lin Weiying , Cao Zengmei , Long Lingliang , Song Jizeng
Published: November 2010

Analyte‐responsive fluorescent probes are valuable chemical tools for dissecting complex living systems. However, the major shortcoming of fluorescent probes is that once they enter the cells, control over them is basically lost. It is critical to regulate fluorescent probes in a spatial and temporal manner, as functions of biomolecules are spatiotemporal. On the other hand, light can be manipulated in time and in the application site, so the photocaging technique allows researchers to control the biomolecules of interest in a temporal and spatial fashion. Herein, we propose for the first time the combination of the merits of sensing and photocaging technologies, which may afford the caging version of analyte‐responsive fluorescent probes, referred to as photocontrollable analyte‐responsive fluorescent probes (PCAFPs). These “smart” fluorescent probes apparently have the intrinsic advantage of spatiotemporal control when compared to traditional fluorescent probes, as the “sensing activity” of PCAFPs is photocontrollable. This should enable biologists to interrogate complex biological systems in a spatial and temporal manner with an innovative chemical tool. In this work, for proof of concept, we report the rational design, synthesis, photocontrollable sensing in solution and in living cells, and mechanistic studies of a molecular prototype of PCAFP for copper as the first paradigm of this new class of smart fluorescent probes. We believe that PCAFPs represent a substantial breakthrough in the sensing and photocaging fields, and that the general concept of PCAFPs should be broadly applicable for a wide variety of biologically relevant species.