bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of Two Educational Systems in Both Basic and Higher Education between Japan and Singapore
Authors: Vicente Ruel S. , Reomero Jarah I. , Flores Loyd C. , Amora Maryrose S. , Almagro Ronald E.
Published: January 2024

The comparative analysis of the educational systems in Japan and Singapore, encompassing both basic and higher education, reveals intriguing insights into the diverse approaches employed by these nations. In terms of basic education structure, Japan follows a 6-3-3 system, comprising six years of elementary education, three years of junior high, and three years of senior high, while Singapore adopts a 4-4-4 system, dividing education into four years each of primary, secondary, and pre-university or vocational education. This structural contrast sets the stage for examining curriculum, instructional methods, assessment practices, teacher training, funding mechanisms, equity considerations, and educational outcomes. Japan's emphasis on national standards and rote learning is juxtaposed against Singapore's focus on critical thinking, problem-solving, and creativity, reflecting varied pedagogical philosophies. Instructional methods further differ, with Japan relying on traditional teacher-centered approaches and Singapore embracing diverse strategies like project-based and collaborative learning. Assessment practices showcase Japan's reliance on standardized national exams, while Singapore employs diverse methods such as internal exams and portfolios. In teacher training, Japan emphasizes subject knowledge and standardized training, while Singapore prioritizes pedagogical skills, continuous professional development, and career progression. The funding landscape diverges, with Japan primarily relying on public funding and limited private involvement, while Singapore fosters a robust public-private partnership for funding and innovation. Equity and access priorities also differ, with Japan expressing concerns about rural-urban disparities, and Singapore emphasizing equal access for all students. Notably, both nations achieve high PISA scores, but Japan grapples with concerns about rote learning and student stress, whereas Singapore excels in international benchmarks. This comparative analysis underscores the nuanced and multifaceted nature of educational systems, providing valuable insights for policymakers, educators, and researchers seeking to understand and learn from the diverse approaches adopted by Japan and Singapore.
An Evaluation of Anti-hyperlipidemic Activity of Ethanolic Extract of Coccinia grandis Leaves in High Fat Induced Rodent Model
Authors: Nisu Rifat Ara , Nadvi Faisal Ahmed , Ankhi Arjina Akter , Suma Sabnam Roy , Papiya Israt Jahan , Bose Ankita
Published: January 2024

In the realm of health research, hyperlipidemia is a condition that has lately become prevalent and is a serious issue. Elevated lipid levels in an individual's body are the primary indicator of hyperlipidemia, a condition defined by increased levels of low-density lipoprotein (LDL), total cholesterol, triglycerides, and high lipoprotein levels. Several pharmacological agents are accessible for the treatment of hyperlipidemia. Nevertheless, human beings throughout the globe also thrive on nature-derived therapeutic items. Coccinia grandis is a noteworthy plant known for its antihyperlipidemic properties among them. In this study, we provided a high-fat diet for the experimental rats to generate hyperlipidemia conditions in this rat model. As per our research methodology, Coccnia grandis was administered to all the rats in the treatment group at three (low, medium and high) distinct dosages. It is eventually revealed that Coccnia grandis may successfully lower (p<0.05) the hyperlipidemic state in both medium and high dosages. Elevated and unusual Triglyceride and Total Cholesterol were observed to be restored following Coccnia grandis medication. However, in the case of HDL and LDL, no substantial drop was detected. A considerable restoration was noted similarly in both instances of SGPT and SGOT. These findings show that our plant has components with antihyperlipidemic action, however the concentrations did not meet the necessary threshold. So, additional investigations are needed to examine the chemical structure and the quantities of the molecule as well as find out about genetic alterations.
Phenotypic and Quantative Characterization of Ber (Ziziphus mauritiana Lamk.) Germplasm under Eastern Region of Uttar Pradesh, India
Authors: Kumar Pradeep , Tripathi V. K.
Published: January 2024

Eastern region of Uttar Pradesh is very rich in biodiversity for ber but still less harnessed. The agro-climatic conditions of eastern region do have great potential for its commercial cultivation. Keeping these in view, fruit sample with shoot were collected from fourty genotypes of ber in diverse areas of eastern region of Uttar Pradesh and analysed for various physiological attributes and results of study shows a wide range of variability in morphological and quantitative parameters. Among the parameters leaf shape of  different genotypes show a wide variation and mainly  Cordate, Oval, Obovate and Elliptic shape are found. The stone shape recorded showed Obtuse, acute, oblong, showed round stone shaped. Among the quantitative variability of different genotypes stone weight (0.56 g to 1.58 g), stem girth (25.90 cm to 62.63 cm) and hight of tree (3.43 m to 5.50 m) varivility was also recorded. Therefore, on the basis of morphological and quantitative attributes, genotypes–7,14,15, 18, 21and 30 were screened as promising genotypes can be recommended for commercial multiplication, growing at farmer’s field and conservation in the field gene bank for further evaluation and crop improvement.
Role of Foliar Application of Micronutrients on Growth and Yield of Pulses: A Review
Authors: Pandey Shruti , Sharma Pavan Kumar , Roy Shreya , Choudhary Dilip , Choudhary Rajendra , Naga Indar Raj , Singh Ravin , Ninama Jigyasa
Published: January 2024

Pulses respond positively to micronutrients application, particularly during the reproductive stages, their application is still uncommon. The current review suggest that foliar application of Zn, Fe or Mo had a favourable impact on growth indicators and grain yield. protein content, total and active nodule counts and yield components plant-1. Molybdenum is essential for the development of nodule tissue and an increase in N2 fixation, both of which are necessary for Rhizobium to increase the nitrogen fixation process.
Impact of Various Nutrient Sources on Black Gram (Vigna mungo L. Hepper) Productivity and Soil Properties of under Organic Farming
Authors: Patel Krutika Subodh , Dubey P. K. , Kaswala A. R. , Italiya A. P. , Neethu T. M.  , Raj Janak
Published: January 2024

A field experiment was conducted in the Organic farm, Department of Natural Resource Management, ASPEE College of Horticulture, Navsari Agricultural University, Navsari, Gujarat in the year 2021 in summer season. The experiment was laid out in Randomized Block Design with Factorial concept (FRBD) comprising of two factors each having three levels i. e. soil application viz., S1 (100 % RDN through NADEP compost), S2 (Ghan-jivamrut @ 500 kg/ha) and S3 (Ghan-jivamrut @ 500 kg/ha + Jivamrut @ 500 l/ha) and foliar application viz., F0 (Control), F1 (Novel organic liquid nutrient @ 1 %) and F2 (Moringa leaf extract@ 3 %) was given thrice at 15, 30 and 45 DAS. The result revealed that S1 treatment significantly recorded the seed yield. While for foliar application, the treatment F2significantly recorded the highest seed yield and stover yield but remained at par with F1 treatment. It can be determined that the soil application of 100 per cent RDN through NADEP compost and foliar application of either 3 per cent Moringa leaf extract or 1 per cent Novel organic liquid nutrient at 15, 30 and 45 DAS resulted in higher yield and also improved the soil properties as compared to the initial status of soil after harvest of black gram under organic farm.
Investigation of Bio Fungicidal Properties of Crude Extracts of Neem Leaf against Blast Disease of Finger Millet (Eleusine coracana)
Authors: Yamunarani K. , Sangeetha S. , Dhanushkodi V. , Chitra K. , Dhanalakshmi K. , Malini N.
Published: January 2024

The efficacy of neem leaf extract against finger millet blast pathogen Magnaporthe grisea was assessed invitro. The neem leaf extract significantly inhibits the pathogen mycelial growth and melanin biosynthesis. Neem leaf extract shows 84.33 % inhibition of the pathogen over control. Volatile test infer that no volatile compounds were found to be involved in growth inhibition and melanin production inhibition. In field experiments foliar spray with neem leaf extract 5%, 10% and 15% along with chemical Tricyclazole 0.1% and Picoxystrobin 6.78% + Tricyclazole 0.1 % was done. Data recorded on leaf blast PDI at 15, 25 and 40 days after transplanting   revealed that lower leaf blast PDI of 17.72, 16.45 and 15.45 respectively was recorded in neem leaf extract (T1,T2,T3) which is comparatively similar with chemical treatment 1 and 2 PDI 13.00 and 10.90.  In neem leaf extract treated field a significant yield increase was also observed.
Study of Genetic Diversity and Drought-Tolerance Characteristics of Few Rice Varieties Using Morphological and Molecular Markers
Authors: Kalita Mridusmita , Saharia Daizi Durba , Thakur Kangkana , Sonowal Santosh , Goswami Ratna Kinkor , Sarma Manoj Kumar , Baruah Aiswarya
Published: January 2024

Rice (Oryza sativa L.) is one of the most important cereal crops. Increasing rice production is constrained by various stresses and drought is one of the major limiting factors. For future food security, assessments of genetic resources are necessary. Indigenous varieties contain a high level of genetic diversity and can serve as potential genetic resources for improving yield, and resistance to various biotic and abiotic stress conditions. The present investigation was conducted in the Biotech Hub, Biswanath College of Agriculture, AAU, Biswanath Chariali during 2022-23.   In this study, the genetic diversity of 27 indigenous rice germplasm using SSR markers was assessed. Out of the total 28 SSR markers screened, 17 were found polymorphic across twenty-seven genotypes with PIC values ranging from 0.076 to 0.499. The genetic diversity was estimated by the Jaccard dissimilarity coefficient. The phylogenetic tree, using unweighted neighbor-joining (UPGMA) drawn from the analysis divides 27 genotypes into 3 clusters. Nine genotypes were further characterized by exposure to drought stress compared to the control condition. Plants were grown in PVC  pipes and subjected  to drought by withdrawing water at 45 days after showing (DAS) for  25 days. A comparative study was done for a few morphophysiological parameters i.e. root length, root biomass, root-shoot ratio, root length density, chlorophyll content etc. It was observed that genotype Dehangi followed by N22 and Shahabhagi showed the best performance for all parameters under drought stress. This information will help in the selection of varieties with better root characteristics for drought tolerance in future breeding programs.
Effect of Different Nutrient Sources on Yield, Nutrient Content and Uptake of Black Gram (Vigna mungo L. Hepper) in Organic Agriculture
Authors: Patel Krutika Subodh , Dubey P. K. , Kaswala A. R. , Italiya A. P. , Neethu T. M.  , Raj Janak
Published: January 2024

The field investigation was conducted to study the influence of different organic nutrient sources on black gram cv. GU 3 at Organic Farm, ASPEE College of Horticulture, Navsari Agricultural University, Navsari, Gujarat during summer season of the year 2021. The experiment was laid out in Randomized Block Design with Factorial concept, consisting of two levels viz., soil application and foliar application each having three factors. Total of nine treatments i. e., S1 :100 % RDN through NADEP compost, S2 : Ghan-jivamrut @ 500 kg/ha and S3 : Ghan-jivamrut @ 500 kg/ha + Jivamrut @ 500 l/ha and that of foliar application were, F0 : Control, F1 : Novel organic liquid nutrient @ 1 % and F2 : Moringa leaf extract @ 3 %. The application of foliar spray was done thrice at 15, 30 and 45 days after sowing. were replicated thrice. The result revealed that the mean data of nutrient content in black gram seed and stover did not significantly change due to soil and foliar application of different organic nutrient sources. The total NPK uptake was recorded significantly the highest with S1 treatment, whereas total K uptake was found statistically similar with the treatment S3. The foliar application of treatment F2 recorded significantly the highest total NPK uptake by crop. So, it can be concluded that providing 100 percent RDN through NADEP compost in the soil and giving 3 percent Moringa leaf extract or 1 percent Novel organic liquid nutrients on days 15, 30 and 45 after planting on leaves gave significantly higher seed yield, stover yield and total N, P and K nutrient uptake compared to the Ghan-jivamrut @ 500 kg/ha and Ghan-jivamrut @ 500 kg/ha + Jivamrut @ 500 l/ha treatments on soil and control.
Prevalence of Obesity and its Association with Academic Performance and Other Factors among Jazan University Medical Students: A Cross-Sectional Study
Authors: Hurissi Eman , Allami Maram , Alhazmi Altaf , Alsomaili Halimah , Gharawi Sarah , Kamili Amal , Homadi Jawahir , Ageeli Fadiyah , Moafa Amirah , Abdelmola Amani , Zanquti Asmaa , Alhazmi Abdulaziz H. , Ghulaysi Saleh
Published: January 2024

Obesity is a condition when excessive adipose tissue accumulates in the body and that negatively affects health through predisposition to the development of many diseases and complications such as diabetes mellitus, cardiovascular disease, hypertension, and hyperlipidemia. Previous studies reported that obesity could influence the academic performance of the affected individual. Thus, we aimed in this study to measure the prevalence of obesity and its associated risk factors among medical students at Jazan University, and how it could affect academic performance.This is a descriptive, observational cross-sectional study that was conducted on medical students of Jazan University, Saudi Arabia, using questions that assess students’ demographic, academic performance and obesity. Data analyzed using t-test and chi-square test. We included 331 participants, most of them female (74%). About half of the participants have normal weight and recorded a high-grade point average (GPA) of 4 or more (out of 5). The highest GPA (4 or more out of 5) was achieved by 31% of students with normal weight, compared to 12% of underweight, 8% of overweight, and 5% of obese students. Being non-obese is associated with a higher GPA. Further, a significant relationship was observed between obesity and GPA (p-value= 0.013), in which obesity has a negative impact on the GPA of the affected students.In conclusion, our study showed that the medical students at Jazan University with normal weight achieved higher GPAs than other weight groups. We also found that food consumption is increasing with stress in overweight and obese students. This result highlights the importance of prevention measures and awareness to improve academic performance among affected students as obesity has well-known complications.
Template Synthesis of Au/Co Multilayered Nanowires by Electrochemical Deposition
Authors: Valizadeh S. , Hultman L. , George J.M. , Leisner P.
Published: December 2002

The electrochemical deposition of Au/Co multilayers into 20 μm‐thick ion track etched polycarbonate membranes with pore diameters of 110–150 nm was studied in a single electrolyte containing cobalt sulfate, gold cyanide, and citric acid. Cyclic voltammetry, chronoamperometry, and pulse‐potential experiments were used to determine the deposition conditions for pure Au and 98 wt.‐% Co layers. The Co‐rich metallic nanowires were deposited at –1100 mV and the Au nanowires at –490 mV vs. Ag/AgCl. Under open‐circuit conditions an Au‐displacement reaction occurred. Open‐circuit conditions were applied in combination with a steep ramp between the Co and Au potential pulses to avoid the otherwise severe Co dissolution when the potential was switched to less negative values. Scanning and transmission electron microscopy of the deposited multilayered nanowires revealed dense and well‐defined layer interfaces. X‐ray diffraction investigations of 20 μm long Au and Co nanowires showed that the Au deposits exhibit a face‐centered cubic (fcc) <111> texture, while the Co deposits exhibit a hexagonal close‐packed (hcp) (002) structure. The magnetic measurements of 12 nm Co/4 nm Au nanowires for fields applied parallel and perpendicular to the film plane indicate a low remnant magnetization.
Triplet Formation In Polyfluorene Devices
Authors: Dhoot A.S. , Greenham N.C.
Published: December 2002

The fraction of excitons formed as singlets governs the efficiency of a polymer light‐emitting diode (LED) (see Figure). By measuring absorptions due to triplet excitons in working poly(9,9‐dioctylfluorene) devices, the singlet formation probability is calculated. A lower limit of 58 % is found, significantly larger than that predicted statistically. In devices based on the copolymer F8BT, no triplet exciton absorption can be detected.
Quantitative Structure‐Activity Relationship Study of Recently Synthesized 1, 4‐Dihydropyridine Calcium Channel Antagonists. Application of the Hansch Analysis Method
Authors: Hemmateenejad Bahram , Miri Ramin , Akhond Morteza , Shamsipur Mojtaba
Published: December 2002

The Hansch analysis method was applied to a series of recently synthesized nifedipine analogues containing nitroimidazolyl, phenylimidazolyl, and methylsulphonylimidazolyl groups at the C‐4 position and different ester substituents at C‐3 and C‐5 positions of the dihydropyridine ring. Hydrophobic, electronic, inductive, and resonance substituent constants were used.The effect of these parameters on the biological activity of 1, 4‐dihydropyridines (calcium channel antagonist activity in Guinea‐pig ileal cells, log (1/IC50)) was determined by multiple linear regression analysis. Linear and quadratic relationships were obtained between the activity and these parameters. Itwas found that both electronic and hydrophobic interactions occur between the nifedipine analogues and the receptor.
Chiral Relay: A Novel Strategy for the Control and Amplification of Enantioselectivity in Chiral Lewis Acid Promoted Reactions
Authors: Corminboeuf Olivier , Quaranta Laura , Renaud Philippe , Liu Mei , Jasperse Craig P. , Sibi Mukund P.
Published: December 2002

Chiral Lewis acid catalysis has emerged as one of the premiere method to control stereochemistry. Much effort has gone into the design of superior ligands with increasing steric extension to shield distant reactive sites. We report here an alternative and complementary approach based on a “chiral relay”. This strategy focuses on the improved design of achiral templates which may relay and amplify the stereochemistry from ligands. The essence of this strategy is that the chiral Lewis acid would effectively convert an achiral template into a chiral non‐racemic template. This approach combines the advantages of enantioselective catalysis (substoichiometric amount of the chiral inducer) with the ones of chiral auxiliary control (efficient and predictable stereocontrol).
Could Redox‐Switched Binding of a Redox‐Active Ligand to a Copper(II) Centre Drive a Conformational Proton Pump Gate? A Synthetic Model Study
Authors: He Zhicong , Colbran Stephen B. , Craig Donald C.
Published: December 2002

A proposal for a redox‐linked conformational gate to proton translocation—a proton pump gate—based upon a transition‐metal redox‐switchable hemilabile ligand (RHL) system is made. Consideration of the requirements for such a system reveals copper(II) to be the ideal metal centre. To test the proposal and, thereby, to provide an artificial proton pump gate, the copper coordination chemistry of three tris(pyridylmethyl)amine (tpa) ligands with one “leg” (PY*) substituted at the 6‐position of the pyridine ring by a dimethoxyphenyl (L1), a hydroquinone (H2L2) or a quinone (L3) substituent has been investigated. Crystal structures of sp‐[Cu(κ4N‐L1)Cl]Cl⋅3 H2O (sp=square pyramidal), sp‐[Cu(κ3N‐H2L2)Cl2] and tbp‐[Cu(κ4N,κO‐HL2)][PF6] (tbp=trigonal bipyramidal) have been determined. The CuI complexes [Cu(L)(MeCN)n]+ (L=L1, H2L2) display physicochemical properties consistent with a “dangling” PY* leg; from the NMR spectra, the barriers to inversion of the ligand amine donor for the CuI complexes are estimated to be within the range of about 30–45 kJ mol−1. In the CuII complexes, coordination of the PY* leg is finely balanced and critically depends on the nature of the PY* substituent and the availability of potential co‐ligand(s). For example, tbp‐[Cu(κ4N‐L1)Cl]+ reacts cleanly with Cl− ions to afford sp‐[Cu(κ3N‐L1)Cl2]; Vis/NIR spectrophotometric titrations suggest the affinity of tbp‐[Cu(κ4N‐L1)Cl]+ for Cl− ion in dichloromethane is 9.7×102 and is at least 104‐fold greater than that of tbp‐[Cu(κ4N‐L3)Cl]+. The complex sp‐[Cu(κ3N‐H2L2)Cl2] has a “dangling” PY* leg, in which an intramolecular OH(hydroquinone)⋅⋅⋅N(pyridine) hydrogen bond “ties‐up” the pyridyl nitrogen atom, and reacts with Brønsted bases to give tbp‐[Cu(κ4N,κO‐HL2)]+. Two‐electron oxidation of sp‐[Cu(κ3N‐H2L2)Cl2] is linked to loss of two protons and a conformational change, and affords tbp‐[Cu(κ4N‐L3)Cl]+. The [Cu(κ3N‐H2L2)Cl2]–[Cu(κ4N‐L3)Cl]+ system provides a first demonstration of the critical step in the proposed proton pumping cycle, namely a redox‐driven and proton‐linked conformational change. The possible biological relevance of this work to proton pumping in cytochrome c oxidase is mentioned.
How To Turn the Catalytic Asymmetric Hydroboration Reaction of Vinylarenes into a Recyclable Process
Authors: Segarra Anna M. , Guerrero Ramon , Claver Carmen , Fernández Elena
Published: December 2002

Optically pure rhodium(I) complexes [Rh(cod)(LL)]X (cod=cyclooctadiene; LL= (R)‐2,2′‐bis(diphenylphosphino)1‐1′‐binaphthyl ((R)‐BINAP), (S,S)‐2,4‐bis(diphenylphosphino)pentane ((S,S)‐BDPP), 2‐diphenylphosphino‐1‐(1′‐isoquinolyl)naphthalene ((S)‐QUINAP); X=BF4, PF6, SO3CF3, BPh4) were immobilised onto smectite clays such as montmorillonite K‐10 (MK‐10) and bentonite (Na+‐M). 19F, 31P and 11B NMR experiments recorded in CDCl3 during the impregnation process provided evidence that montmorillonite K‐10 may immobilise ionic metal complexes throughout the cationic and anionic counterparts. However, when bentonite was used as the solid, only the cationic metal complex was immobilised through cationic exchange while the counteranion remained in solution. When we used these preformed catalytic systems in the hydroboration of prochiral vinylarenes, we obtained high activities and enantiomeric excess with (S)‐1‐(2‐diphenylphosphino‐1‐naphthyl)isoquinoline‐modified rhodium complexes. These activities and selectivities are competitive with the homogeneous counterparts. The significant features of this method are the simple separation and good retention of the active metal in the solid, which allows efficient recycling even on exposure to air.
High Thermodynamic Stability and Extraordinary Kinetic Inertness of Copper(II) Complexes with 1,4,8,11‐Tetraazacyclotetradecane‐1,8‐bis(methylphosphonic acid): Example of a Rare Isomerism between Kinetically Inert Penta‐ and Hexacoordinated Copper(II) Complexes
Authors: Kotek Jan , Lubal Přemysl , Hermann Petr , Císařová Ivana , Lukeš Ivan , Godula Tomáš , Svobodová Ivona , Táborský Petr , Havel Josef
Published: December 2002

In an aqueous solution at room temperature, 1,4,8,11‐tetraazacyclotetradecane‐1,8‐bis(methylphosphonic acid) (H4L1) and CuII form a pentacoordinated (pc) complex, pc‐[Cu(L1)]2−, exhibiting conformation I of the cyclam ring. At high temperature, the complex isomerises to a hexacoordinated isomer, trans‐O,O‐[Cu(L1)]2−, with a trans‐III conformation of the cyclam ring. In pc‐[Cu(L1)]2−, four ring nitrogen atoms and one phosphonate oxygen atom are arranged around CuII in a structure that is half‐way between a trigonal bipyramid and a tetragonal pyramid, with one phosphonic acid group uncoordinated. In the trans‐O,O‐[Cu(L1)]2− isomer, the nitrogen atoms form a plane and the phosphonic acid groups are in a mutually trans configuration. A structurally very similar ligand, 4‐methyl‐1,4,8,11‐tetraazacyclotetradecane‐1,8‐bis(methylphosphonic acid) (H4L2), forms an analogous pentacoordinated complex, pc‐[Cu(L2)]2−, at room temperature. However, the complex does not isomerise to the octahedral complex analogous to trans‐O,O‐[Cu(L1)]2−. Because of the high thermodynamic stability of pc‐[Cu(L1)]2−, (log β=25.40(4), 25 °C, I=0.1 mol dm−3 KNO3) and the formation of protonated species, CuII is fully complexed in acidic solution (−log [H+]≈3). Acid‐assisted decomplexation of both of the isomers of [Cu(H2L1)] takes place only after protonation of both uncoordinated oxygen atoms of each phosphonate moiety and at least one nitrogen atom of the cycle. The exceptional kinetic inertness of both isomers is illustrated by their half‐lives τ1/2=19.7 min for pc‐[Cu(H2L1)] and τ1/2 about seven months for trans‐O,O‐[Cu(H2L1)] for decomplexation in 5 M HClO4 at 25 °C. The mechanism of formation of pc‐[Cu(L1)]2− is similar to those observed for other macrocyclic complexes.

For classification of the cyclam ring conformation in complexes, see B. Bosnich, K. Poon, M. Tobe, Inorg. Chem. 1965, 4, 1102.
Amination of Benzylic CH Bonds by Arylazides Catalyzed by CoII–Porphyrin Complexes: A Synthetic and Mechanistic Study
Authors: Ragaini Fabio , Penoni Andrea , Gallo Emma , Tollari Stefano , Li Gotti Claudia , Lapadula Marta , Mangioni Enrica , Cenini Sergio
Published: December 2002

CoII–porphyrin complexes catalyze the reaction of aromatic azides (ArN3) with hydrocarbons that contain a benzylic group (ArR1R2CH) to give the corresponding amines (ArR1R2CNHAr). When at least one of the R substituents is hydrogen, the catalytic reaction proceeds further to give the imine ArRCNAr in good yields. The reaction mechanism has been investigated. The reaction proceeds through a reversible coordination of the arylazide to the CoII–porphyrin complex. This unstable adduct can either react with the hydrocarbon in the rate‐determining step or decompose by a unimolecular mechanism to afford a putative “nitrene” complex, which reacts with more azide, but not with the hydrocarbon, to afford the byproduct diaryldiazene. The kinetics of the catalytic reaction have been investigated for a range of azides and substituted toluenes. Arylazides with electron‐withdrawing substituents react at a faster rate and a good correlation is found between the log(k) and the Taft parameters. On the other hand, an excellent correlation between the logarithm of the rate for substituted toluenes relative to that of toluene and a radical parameter (σ$\rm{_{JJ}^{{\bf \cdot }}}$) alone was found, with no significant contribution by polar parameters. An explanation has been proposed for this anomalous effect and for the very high isotopic effect (kH/kD=14) found.
Monte Carlo Simulation of the Assembly of bis‐Biotinylated DNA and Streptavidin
Authors: Richter Jan , Adler Michael , Niemeyer Christof M.
Published: December 2002

We present Monte Carlo simulations of the self‐assembly of bivalent bis‐biotinylated DNA molecules with the tetravalent biotin‐binding protein streptavidin (STV). By fitting the STV binding probabilities for the four possible valencies, the modelling correctly reproduces the dependencies of various network parameters experimentally observed in an earlier study. The combined results from the experimental and theoretical studies suggest that the binding probability for divalent STV formation is about 50 times larger than for the formation of trivalent and about 200 times larger than for tetravalent STV. In accordance with the experimental results, the modelling also indicates that the mixture of an equimolar ratio of DNA and STV leads to a maximum in size of the oligomeric DNA–STV clusters formed. Furthermore, we found a percolation transition in which the DNA cluster size increases rapidly with increasing DNA concentration resulting in the formation of a single supercluster at elevated concentrations. This behaviour coincides with the occurrence of an immobile band previously observed in electrophoretic experiments, indicating the formation of extremely large DNA–STV aggregate networks.
Syntheses of Purines Bearing Carbon Substituents in Positions 2, 6 or 8 by Metal‐ or Organometal‐Mediated C−C Bond‐Forming Reactions
Authors: Hocek Michal
Published: December 2002

Approaches to the synthesis of purine derivatives bearing carbon substituents in positions 2, 6, or 8, mediated and/or catalysed by organometallic compounds and metals, are reviewed. Both the generation and the reactions of purinylorganometallic compounds are covered, as well as cross‐coupling and cycloaddition reactions between purines and organometallic compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Unexpected Conversion of 1,5,8,12‐Tetraazadodecane‐Glyoxal Bisaminal into Its Amidinium Salt in an Acidic Medium
Authors: Bernard Hélène , Del Rio Garcia Eugenia , Ferec Sonia , Kervarec Nelly , Handel Henri
Published: December 2002

When refluxed in aqueous hydrochloric acid solution, 1,5,8,12‐tetraazadodecane‐glyoxal bisaminal is quantitatively converted into its amidinium salt, which is a lactam precursor. The mechanism of this unexpected reaction is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Eur. J. Org. Chem. 2/2003
Authors: Tomasini Claudia , Trigari Valerio , Lucarini Simone , Bernardi Fernando , Garavelli Marco , Peggion Cristina , Formaggio Fernando , Toniolo Claudio
Published: December 2002

The cover picture shows the side views of the DFT‐optimized Boc‐(L‐Oxd)n‐OBn (n = 2−5) foldameric structures (in the circle) and the front view of Boc‐(L‐Oxd)5‐OBn (in the centre). Details are discussed in the article by M. Garavelli, C. Toniolo et al. on p. 259 ff.
Two morphological types of pineal window in catfish in relation to photophase and scotophase activity: a morphological and experimental study
Authors: Srivastava S.
Published: December 2002

The pineal window is a transparent/translucent pineal covering on the dorsal surface of the cranium of certain fishes and is associated with light reactions of fish. In the present study, catfish species Clarias batrachus, Heteropneustes fossilis, Mystus vittatus, M. seenghala, and M. cavassius were examined for the type of pineal window present. Two morphologically different types of pineal window were found: an opaque‐looking pineal window in C. batrachus and H. fossilis and a translucent type of pineal window in M. vittatus, M. seenghala, and M. cavassius. The distributional pattern of pigments in the melanophores at the pineal window were studied in terms of Melanophore Index (MI). In all of the species studied, a pineal foramen, a subepidermal lens‐like tissue, and pineal end vesicle were present.

Experiments were carried out on catfish having the opaque pineal window, as it is uncommon in catfish. Catfish with normal and shielded pineal window were exposed to conditions of artificial constant illumination (LL) and darkness (DD) to evaluate the effects of altered photoperiods on the state of pigmentation of melanophores at the pineal window. Recordings of diel activity patterns, which are light dependent in catfish, were carried out under both natural and artificial photoperiods in fish with a normal or shielded window in order to assess its functional nature. The existence of two morphologically and functionally different types of pineal window in a relatively closely related group of catfish has been demonstrated in this study. The nature of the opaque type of pineal window has been reconsidered based on new experimental evidence. J. Exp. Zool. 295A:17–28, 2003. © 2003 Wiley‐Liss, Inc.
Simulation and Evaluation of Compounding Processes
Authors: Potente Helmut , Kretschmer Karsten
Published: December 2002

Co‐rotating twin‐screw extruders are the most important types of machine for the compounding of plastics from the economic point of view. The term ‘compounding’ is basically used to describe all processes that are needed to produce a plastic with a desired property profile from the raw polymer. In most processes found today, multi‐component material systems are used. These may consist of polymer/filler combinations (compounds) or polymer/polymer combinations (blends). After presenting mathematical models to describe the behavior of binary systems, a description is given of the melting profile of polymer/filler compounds. After this, models are presented that enable the degree of dispersion of compounding processes to be calculated. These models have been implemented in a software program for simulating the process characteristics of co‐rotating twin‐screw extruders. With the aid of this software, it is possible to conduct a comprehensive analysis of the process behavior of co‐rotating twin‐screw extruders. The processing unit can then be optimized on the basis of this analysis.

Screw configuration for examining the dispersion.

magnified image

Screw configuration for examining the dispersion.
Improved Design of Shearing Sections with New Calculation Models Based on 3D Finite‐Element Simulations
Authors: Potente Helmut , Többen Wilhelm H.
Published: December 2002

New models for the Maddock and spiral shearing sections have been developed, employing three‐dimensional finite element analysis (3D FEA). These models describe the pressure‐throughput and power consumption behavior of the shearing sections for both the extrusion and the injection molding process and have been implemented in the REX 6.0 and PSI 4.0 simulation software. As a consequence it is now possible to describe the process behavior of these shearing sections within just a few seconds with the accuracy of FEA calculations.

Actual Maddock shearing section (left) and actual spiral shearing section (right).

magnified image

Actual Maddock shearing section (left) and actual spiral shearing section (right).
Global Concept for Describing and Investigation of Wall Slip Effects in the Extrusion Process
Authors: Potente Helmut , Ridder Helmut , Cunha Renata Viegas
Published: December 2002

When it comes to the design of extrusion line components such as single‐screw extruders or extrusion dies, no one has yet succeeded in developing a well‐functioning concept for wall‐slipping materials. This article examines the fundamental influences of the wall slippage effect on flow behavior in the extrusion die and plastification unit. New and extended methods of calculation for describing this flow phenomenon are presented for both these extrusion line components, and the general possibilities for linking the two approaches are discussed.

Diagram of the flow curve (τ = shear stress, $\dot \gamma$ = shear rate) of wall‐slipping plastics for constant pressure.

magnified image

Diagram of the flow curve (τ = shear stress, $\dot \gamma$ = shear rate) of wall‐slipping plastics for constant pressure.
Sperm surface hyaluronan binding protein (HABP1) interacts with zona pellucida of water buffalo (Bubalus bubalis) through its clustered mannose residues
Authors: Ghosh Ilora , Datta Kasturi
Published: December 2002

Sperm–oocyte interaction during fertilization is multiphasic, with multicomponent events, taking place between zona pellucida (ZP) glycoproteins and sperm surface receptor. d‐mannosylated glycoproteins, the major constituents of ZP are considered to serve as ligands for sperm binding. The presence of hyaluronan binding protein 1 (HABP1) on sperm surface of different mammals including cattle and its possible involvement in sperm function is already reported. Recently, we have demonstrated the specificity of clustered mannose as another ligand for HABP1 (Kumar et al., 2001: J Biosci 26:325–332). Here, we report that only N‐linked mannosylated zona‐glycoproteins bind to sperm surface HABP1. Labeled HABP1 interacts with ZP of intact oocyte of Bubalus bubalis, which can be competed with unlabeled HABP1 or excess d‐mannosylated albumin (DMA). This data suggests the specific interaction of HABP1 with ZP, through clustered mannose residues. In order to examine the physiological significance of such an interaction, the capacity of sperm binding to oocytes under in vitro fertilization plates was examined either in presence of DMA alone or in combination with HABP1. The number of sperms, bound to oocytes was observed to reduce significantly in presence of DMA, which could be reversed by the addition of purified recombinant HABP1 (rHABP1) in the same plate. This suggests that sperm surface HABP1 may act as mannose binding sites for zona recognition. Mol. Reprod. Dev. 64: 235–244, 2003. © 2003 Wiley‐Liss, Inc.
Optimization of superovulation induction by human menopausal gonadotropin in guinea pigs based on follicular waves and FSH‐receptor homologies
Authors: Suzuki Osamu , Koura Minako , Noguchi Yoko , Takano Kaoru , Yamamoto Yoshie , Matsuda Junichiro
Published: December 2002

The guinea pig represents an excellent animal model for the study of reproduction in humans and most domestic animals because unlike the mouse and rat, it undergoes a complete estrous cycle. In this study, we investigated the availability of ovarian oocytes during the estrous cycle, and the follicle stimulating hormone (FSH) receptor (FSH‐R) homologies between guinea pigs and other species, in order to identify an effective gonadotropin and optimal time‐of‐application for the induction of superovulation in the guinea pig. The number of collectable ovarian oocytes showed biphasic changes with peaks at the midluteal and pre‐ovulatory stages. On the other hand, the number of oocytes that matured in vitro remained constant (∼10 oocytes) until day 14 post‐ovulation and increased thereafter. The deduced amino acid sequence of the guinea pig FSH‐R showed greater similarity to the primate FSH‐R than to the rodent FSH‐R, which suggests that commercially available human menopausal gonadotropin (hMG) may be a better inducer of superovulation in guinea pigs. Indeed, significantly more oocytes (5.4 ± 1.6, range 0–17, n = 10) were obtained from hMG‐treated guinea pigs at the pre‐ovulatory stage than during spontaneous ovulation (3.6 ± 0.1, n = 96; P < 0.05), whereas guinea pigs that received hMG at the midluteal stage (n = 3) did not ovulate. These results indicate that hMG is an effective, albeit stage‐dependent, inducer of superovulation in the guinea pig, and that FSH‐R homologies should be taken into account when choosing hormones for superovulation. Mol. Reprod. Dev. 64: 219–225, 2003. © 2003 Wiley‐Liss, Inc.
Mean Particle Diameters. Part III: An Empirical Evaluation of Integration and Summation Methods for Estimating Mean Particle Diameters from Histogram Data
Authors: Alderliesten Maarten
Published: December 2002

Mean particle diameters of histograms of size distributions were estimated by integration and by summation over the histogram intervals using several, partly model, size distributions. The Summation method, used in the Moment‐Ratio (M‐R) method, tends to be more accurate than the Integration method and is less sensitive to low values of the lower limit of size distributions. The mathematical equations for the Integration method appear to be difficult to apply in daily practice and their complexity may easily hide the physical background of a mean particle diameter. The Integration approach leads to peculiar saw‐tooth shaped histograms, which makes the calculation of (histograms of) density distributions of other particle quantities irreversible and the calculation of mean diameters ambiguous. The Summation method equations are straightforward and generally applicable. Owing to the use of midpoints of particle size classes, the method is both unambiguous and reversible. The order of a mean diameter appears to be a useful quantity for the visualization of properties of methods to estimate mean particle diameters. The Summation method is therefore proposed as the method of choice for standardization.
Simultaneous Measurement of Particle Size and Particle Velocity by the Spatial Filtering Technique
Authors: Petrak Dieter
Published: December 2002

The objective of this study was to compare the measuring results of a fiber‐optical probe based on a modified spatial filtering technique with given size distributions of different test powders and also with particle velocity values of laser Doppler measurements. Fiber‐optical spatial filtering velocimetry was modified by fiber‐optical spot scanning in order to determine simultaneously the size and the velocity of particles. The fiber‐optical probe system can be used as an in‐line measuring device for sizing of particles in different technical applications. Spherical test particles were narrow‐sized glass beads in the range 30–100 μm and irregularly shaped test particles were limestone particles in the range 10–600 μm. Particles were dispersed by a brush disperser and the measurements were carried out at a fixed position in a free particle‐laden air stream. Owing to the measurement of chord lengths and to the influence of diffraction and divergent angle, the probe results show differences from the given test particle sizes. Owing to the particle‐probe collisions, the mean velocity determined by the probe is smaller than the laser Doppler mean velocity.
Raman Spectroscopy of Laser‐Shocked Nitrobenzene
Authors: Kozu Naoshi , Kadono Toshihiko , Hiyoshi Reiko I. , Nakamura Jun , Arai Mitsuru , Tamura Masamitsu , Yoshida Masatake
Published: December 2002

A technique for in situ Raman spectroscopy of laser‐shocked nitrobenzene was developed. Raman spectra of shocked nitrobenzene are obtained up to ∼3.5 GPa, and peak shifts at particular frequencies are observed. The shifts are plotted as a function of density and compared with the data under isothermal compression. Both data provide the same results. This indicates that the numbers of peak shifts of nitrobenzene depend solely on material density.
Effect of incident probe on HAADF STEM images
Authors: Watanabe K. , Nakanishi N. , Yamazaki T. , Kawasaki M. , Hashimoto I. , Shiojiri M.
Published: December 2002

Atomic‐resolution incoherent high‐angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images of [011]‐oriented Si have been recorded using different incident beam probes, and analysed by means of dynamical image calculation based on the Bloch wave description. It is shown how atomic‐resolution images are influenced by the semiangle of the probe and the spherical aberration and defocus of the probe‐forming lens. The resolution of an incoherent HAADF STEM image can be simply perceived by the contrast transfer function of incoherent imaging which is the Fourier transform of the incident probe intensity.
Tunable spin‐injection and magnetoconductance in a novel 2DEG‐ferromagnet structure
Authors: Jiang Y. , Jalil M. B. A.
Published: December 2002

In this paper, we calculate the spin‐dependent ballistic transport through a two‐dimensional electron gas (2DEG) heterostructure sandwiched between two ferromagnetic metal (FM) layers. A strong spin‐injection effect is predicted when the magnetization directions of two FM layers are antiparallel. The spin‐injection rate can be tuned by both, applied voltage and magnetic field. The device also exhibits a significant magnetoconductance (MC) when the relative magnetization of FM layers is switched, which functions as a spin‐valve (SV). Using a GaAs system as a 2DEG material in our calculation, the MC can be tuned by both the applied voltage and the magnetic field, and reaches up to as high as 37.5%. The device's dual spin‐valve and spin‐injector characteristics open the possibility for spin electronic and sensor applications in semiconductor based systems.
Far‐infrared optical spectrum of donor impurities in quantum dots in a magnetic field
Authors: Pacheco M. , León A. , Barticevic Z.
Published: December 2002

We report calculations for far‐infrared absorption in GaAs/Ga1–xAlxAs quantum dots doped with shallow‐donor impurities in the presence of a magnetic field. The wave functions and the eigenvalues are obtained in the effective‐mass approximation by using a variational approach in which the ground and excited magneto‐impurity states are simultaneously obtained. The allowed intra‐donor transitions have been investigated by using far‐infrared radiation circularly polarized in the plane perpendicular to the magnetic field. We present results for the absorption coefficient as a function of the photon energy for several field strengths and arbitrary impurity positions. We have found that, as a consequence of the quantum dot confinement the infrared magneto‐absorption strongly depends on the position of the impurity in the dot.
Ecosystem health assessment in five shallow tropical waterbodies
Authors: Datta Subhendu , Jana B. B.
Published: December 2002

Ecosystem health of five shallow tropical perennial waterbodies differing in pollution and productivity histories was evaluated by examining chemical parameters of water, biological production, and the Shannon diversity index. Samples of surface water were monitored every two weeks for pH, total hardness, chemical oxygen demand, dissolved oxygen, dissolved organic carbon, different species of nitrogen (ammonium, nitrite and nitrate nitrogen) and phosphorus (soluble reactive phosphate and total phosphorus) during the period of investigation. Net primary production of phytoplankton and abundance of zooplankton were also determined at biweekly intervals. High organic input either through bathing and domestic activities of large number of pilgrims during a 15-day annual fair in pond 2 or discharge of effluents from a brewery in pond 4 resulted in a sharper rise of net primary production than in the moderately manured fish pond (pond 3) or oligotrophic water body (pond 1). Influx of alkali from a gas factory into pond 5 was responsible for low net primary production and zooplankton abundance. The variability of net primary production in these waterbodies was primarily attributable to the variations of different species of phosphorus and nitrogen of surface water. Spatial and seasonal variability of some chemical indices such as chemical oxygen demand, dissolved oxygen and organic carbon concentrations suggested that pond 4 was more stable due to a consistent effluent discharge and pond 2 was less stable because of seasonal anthropogenic activity. The mean values of Shannon index of general diversity of zooplankton remained between 2.1 and 2.41 in pond 2 and showed the diversity pattern as in pond 1 and pond 3, whereas it remained between 1.0 and 2.0 in ponds 4 and 5, which suggested that stable chemical load throughout the year in these ponds resulted in loss of ecosystem health.