bluuebunny/crossref_metadata_2025 huggingface dataset:
ELECTROLYTE ELECTROREFLECTANCE (EER) SPECTROSCOPY OF ION IMPLANTED SILICON LAYER
Authors: QIAN YOU-HUA  , CHEN LIANG-YAO  ,   复旦大学物理系
Published: November 2020

A phosphorus implanted p-Si layer with dose slightly higher than its critical value was studied by EER combined with stripping-etching technique. The concept of a certain optimal wavelength, named "Specially Effective Wavelength" (SEW), is introduced for the optical measurements of structurally disordered materials. At SEW, the absorption coefficients of a material with different degree of disorder, from crystalline to amorphous, are all equal. For Si, the SEW is approximately 3490 ?, i. e. hω～3.55 eV (in the E1, E1 + △1 region), and the corresponding absorption coefficient is 106cm-1 independent of its degree of disorder. The depth profile of (△R/R)3.55ev is related to that of disorder degree, and the characteristic relations △R/R(D) were obtained for all of the three depth regions. The resulting curve for the implant-damaged region is similar to that reported by Anderson et al. for GaAs layers implanted with inert elements ions. By use of stripping, the observation of the disorder degree dependence of the 3.4 eV structure lineshapes has been realized in a wide range with only one sample. A comparison is made with the lineshape features of vacuum evaporated Ge films. Some conclusions have been drawn from these measurements about the mixed lattice interaction origin of the 3.4 eV spectral region of silion. It has been confirmed that EER is a powerful technique with extremely high sensitivity for the investigation of ion implanted semiconductor layers.
SCANNING PHOTOACOUSTIC MICROSCOPY
Authors: ZHANG SHU-YI  , YU CHAO  , MIAO YONG-ZHI  , TANG ZHENG-YAN  , GAO DUN-TANG  ,   (1)南京大学声学研究所; (2)南京大学物理系
Published: November 2020

The principle, possible applications and prospects of the scanning photoacoustie microscopy are described briefly. The microscopy system presented herewith attains a resolution of about 4,5 μm. Some images of such samples as the interdigital transducer of surface acoustic wave, integrated circuit and in particular the subsurface structure of the materials have been obtained by measuring the amplitude or the phase angle of the photoacoustie signal. These preliminary results show the potential applications of this device in solid state physics, material science and even medical science.
THE ABSORPTION SPECTRUM OF YAlO3:Nd3+
Authors: SONG ZENG-FU  , LIAN SHAO-REN  , HUA DAO-HONG  , WANG SHU-KUN  ,   北京大学物理系
Published: November 2020

At temperatures of 10 K, 90 K and 300 K, the absorption spectra of YA1O3:Nd3+ are systematically examined in the region of 0.33-5.7 μm. The Stark's sub-levels by the action of the crystalline field are assigned. In addition, the temperature effect of a few spectra in the temperature range of 10-663 K are observed and some interesting results are obtained.
THE COMPETING EFFECT OF STIMULATED SCATTERING IN PARAMETRIC OSCILLATION OF BACKWARD WAVE
Authors: FAN JUN-YIN  , WU CUN-KAI  , WANG ZHI-YING  ,   中国科学院上海光学精密机械研究所
Published: November 2020

In this paper the behavior of degenerate four wave mixing and parameteric oscillation of backward wave under strong pumping condition is analysed theoretically. Considering the competing effect of Raman scattering, the dependence of intensity of parametric backward wave oscillation on the pumping intensity is obtained. The theoretical result agrees well with the experiment for nitrobenzene. The analysis also shows that the intensity of parametric oscillation is a multi-valued function of the pumping intensity due to the intensity-dependent attenuation coefficient.
PAIR CORRELATION FUNCTIONS AND EQUATIONS OF STATE OF DENSE MULTI-COMPONENT PLASMAS
Authors: LU QUAN-KANG  ,   复旦大学物理系
Published: November 2020

In this paper, we analyse the pair correlation effects of a multicomponent plasma system in which the electron-electron, ion-ion and ion-electron correlations are considered. The equation of state for a dense bi-maxwellian plasmas are derived.
NEW FORMULAE FOR CALCULATING MELTJNG TEMPERA-TURE, GRüNEISEN PARAMETER AND ISOTHERMAL PRESSURE OF METALS UNDER HIGH PRESSURE
Authors: XIE PAN-HAI  ,   成都901研究所
Published: November 2020

In this paper, a new melting equation is derived. Based on this equation, a formula for calculating Grüneisen Parameter and an isothermal equation of state are obtained through the Lindeman equation. We show that the new equations are reasonable by comparing them with known theoretical and experimental results.
7Li NMR INVESTIGATIONS IN AMORPHOUS IONIC CONDUC-TOR Li2B2O4
Authors: WANG GANG  , LI ZI-RONG  , CHEN LI-QUAN  , WANG LIAN-ZHONG  ,   中国科学院物理研究所
Published: November 2020

In order to understand the mechanism of the ionic conductivity enhancement during pre-crystallization process, we have performed 7Li NMR investigations on amorphous ionic conductor Li2B2O4. The temperature dependence of 7Li NMR spectra is studied. It is found that 7Li NMR spectra in crystalline, amorphous samples and amorphous sample with small amounts of crystallites are very different from each other. An additional peak is observed to overlap 7Li NMR absorption line on amorphous sample with small amounts of crystallites. This phenomenon is similar to that in LiCl (or LiI) containing dispersed secondphase particles. 7Li NMR investigations on amorphous ionic conductor B2O3-0.7Li2O-0.7LiCl is also made, the results are similar to that mentioned above. It is concluded that they are all caused by the interfacial effect between amorphous matrix and the crystallites.
USING MOS STRUCTURE TO STUDY THE DEEP LEVEL OF QUARTERNARY MIXED CRYSTAL In0.75Ga0.25As0.58P0.42
Authors: BAO QING-CHENG  , WANG QI-MING  , PENG HUAI-DE  , ZHU LONG-DE  , GAO JI-LIN  ,   (1)中国科学院半导体研究所; (2)中国科学院半导体研究所,研究生中国科学院长春物理研究所
Published: November 2020

By means of MOS-DLTS method, two electron traps in LPE n-type In0.75Ga0.25As0.58P0.42 material have been observed. Their depths are 0.20 eV and 0.48 eV below conduction band, and capture cross sections of electrons are about 14×10-16cm2 and 3.8×10-12cm2, respectively.Some discussion on the method applied to studying DLTS of multilayer composition semiconductor materials are also given.
THE NON-GEOMETRICAL OPTIC SOLUTION FOR THE ALFVEN WAVE IN DOUBLE PLASMA BEAM MODEL
Authors: SHI CHANG-HE  ,   北京大学地球物理系
Published: November 2020

We used the smooth pertubation method to treat the problem of Alfven wave propagation in double, plasma system. The wave propagation is analysed for two cases. One is that when the dense homogeneous beam moves in an inhomogeneous background plasma and the another one is the opposite situation.The results are briefly discussed.
CALCULATION OF PROJECT ION-RANGE DISTRIBUTION MOMENTS IN COMPOUNDS AND ALLOYS (I)——RANGE DISTRIBUTION MOMENTS FOR HEAVY IONS (Z1>10)
Authors: Xia Yue-yuan  , Yang Hong  , Tan Chun-yu  , Li Jin-hua  ,   (1)山东大学计算机科学系; (2)山东大学物理系
Published: November 2020

Project range and range distribution moments up to third order for twelve ion species implanted into five different substrates (such as amorphous A12O3, SiO2, UO2, LiNbO3 and 20/25/Nb stainless steel) are calculated using an improved nuclear scattering function developed recently. Some results are given for the ions considered with energy range from 5 keV to 1 MeV. The present theoretical results are compared with those published by Gibbons et al. and Winterbon, and our results are proved to agree with the recent experimental measurements more closely. The calculation method which deals with the range distribution moments in amorphous compounds and alloys is presented in some detail, and a brief discussion on the calculation accuracy is given.
LOCALISATION OF ENERGY IN GENERAL RELATIVITY
Authors: Liu Wen-sen  ,   山西大学物理系
Published: November 2020

The main statements of paper [1] are critically reviewed and the blunders in the deduction are indicated. It is showend that the total energy-momentum complex proposed in paper [1] and the energy of gravitational field in a finite part of space are not unique under pure spatial transformation and, therefore, are not possessed of a definite physical meaning.
Study of coupling the age-structured contact patterns to the COVID-19 pandemic transmission
Authors: Wang Guo-Qiang , Zhang Shuo , Yang Jun-Yuan , Xu Xiao-Ke ,   Complex Systems Research Center, Shanxi University, Taiyuan 030006, China,   Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease Control and Prevention, Shanxi University, Taiyuan 030006, China,   College of Information & Communication Engineering, Dalian Minzu University, Dalian 116600, China
Published: November 2020

Background: The coronavirus disease 2019 (COVID-19) has raged more than 10 months and it has become a major public health concern. It is necessary to account for the intrinsic mechanisms and reveal the transmission pattern. Method: We collect detailed information of 944 COVID-19 cases in Guangdong province from January 23rd to February 16th. According to the age-structured characteristics, the population is divided into four groups such as child group (0–5 years old), adolescent group (6–19 years old), young and middle-aged group (20–64 years old), elderly group (65 and over years old). Coupling with different age-structured contact patterns, we establish a discrete age-structured COVID-19 model, obtain the basic reproduction number and final size. By Markov Chain Monte Carlo numerical method (MCMC), we identify the model parameters, fit the cumulative cases, calculate eradiation time of disease, infection peak and the peak arrival time, etc. Results: We found that the most infected people are the young and middle-aged individuals; Compared with household quarantine measure, the peak value of hospitalizations among young and middle-aged group in community mode will increase of 41%, and the peak will delay two weeks. By analyzing the proportions of the final sizes associated age groups, it is found that the elderly have a higher susceptibility, while the adolescents have a lower susceptibility. Under the household quarantine measure, if infected individuals have been confirmed in time of half a day, the peak size of hospitalizations will be further reduced, and the peak hospitalization will advance one week. The model reveals social contact patterns for impacting on COVID-19 transmission, and evaluates the effectiveness of household quarantine.
Analysis of terahertz wave attenuated by sand and dust storms with different modes
Authors: Wang Hong-Xia , Zhang Qing-Hua , Hou Wei-Jun , Wei Yi-Wei ,   Basic Department, Rocket Force Engineering University, Xi’an 710025, China
Published: November 2020

The research on space transmission characteristics of terahertz wave is of great significance for the application of terahertz wave in space. In order to study the transmission characteristics of terahertz wave in sand and dust storm weather, according to the lognormal distribution of dust particle sizes, Mie scattering theory and Monte Carlo method are used to analyze the attenuation characteristics of six dry sand modes of sand and dust storm in different regions of China in a frequency band of 1–10 THz, and the relationship of the extinction parameters and attenuation rate to the frequency is given. The results show that with the increase of frequency, the attenuation rate of 1–10 THz terahertz wave first increases and then decreases. Different mode of sand and dust storm leads to different frequency range of strong attenuation of terahertz wave. In order to analyze the influence of sand dust particle moisture content on terahertz wave propagation attenuation, the relationship of three efficiency factors to water content of sand dust particles with different sizes is calculated. The results show that the influence of water content on extinction is different from that of the particle size. Monte Carlo method is used to calculate the attenuation of terahertz wave by sand and dust storm in two kinds of wet sand modes, and the relationship of the attenuation rate and water content to the frequency is given, the results are compared with those from the dry sand mode, showing that the albedo of wet sand mode is obviously lower than that of dry sand mode with the same size distribution. The absorption of wet sand particles increases with water content increasing. The extinction of wet sand and dust storm results from scattering and absorption. With the increase of water content in sand particles, the frequency band with strong attenuation of terahertz wave by wet sand and dust storm moves toward low frequency. When the water content is less than 5%, the attenuation rate of terahertz wave increases significantly with the increase of water content. Sand and dust storms with higher humidity have a greater influence on the transmission attenuation of terahertz wave.
The future Barents Sea, risks, mitigation and adaptation options
Authors: Planque Benjamin , Arneberg Per , Skern-Mauritzen Mette , Eldevik Tor , Mikkelsen Nina
Published: November 2020

A joint workshop by the Nansen Legacy and Barents Risk projects, to explore the possible states of the Barents Sea by the horizon 2050, the associated risks and the possible ways to mitigate or adapt to them.
The Structure and Genesis of One Type of Magic Spell Against Children’s Insomnia among Slavic Peoples
Authors:   Russian Academy of Sciences, Russia, Agapkina Tatiana , Toporkov Andrei ,   Gorky Institute of World Literature, Russia
Published: November 2020

Among Slavic charms for children who suffer from insomnia, there are texts depicting mothers going out of their houses, carrying their babies while looking at the forest or a single tree and reciting a magic spell addressed to a mythological character, asking for the creature’s help in taking away the baby’s cries and restoring the baby’s sleep. One variation of such texts originates from a manuscript called Summa de confessionis discretione. This text was compiled in Latin by a monk named Rudolf, evidently in the middle of the thirteenth or the beginning of the fourteenth century. The fact that the magic spells for insomnia in children seem to have existed already in the thirteenth or fourteenth century, and that in the nineteenth and twentieth centuries they were widely spread on the broad territory where Eastern, Southern, and Western Slavs lived, testifies to the ancient origins of this type of magic spell.
A Local Midwife or a Doctor? Two Systems of Knowledge in Birthing Practices of Russian Old Believers
Authors:   Russian Presidential Academy of National Economy and Public Administration, Russia, Dushakova Natalia
Published: November 2020

The article explores complex relationships between traditional midwifery and medical institutions as two legitimate knowledge systems in the communities of Russian Old Believers in the Republic of Moldova and in Romania. It is aimed at discussing beliefs and practices around giving birth with the help of a local midwife from the same community, their transformation caused by the access to maternity hospitals as well as distribution of roles between a traditional birth attendant and a doctor. The article is based on oral narratives of Old Believers who used to be local midwives or gave birth to children with the help of such a specialist. The narratives were recorded by the author in 2008–2018.
“How I Gave Birth” (and Why I Am Writing about It): Women’s Narratives of First Childbirth Experiences from Internet Publications
Authors:   Ural Branch of the Russian Academy of Sciences, Russia, Gramatchikova Natalia
Published: November 2020

This article is dedicated to the research of the structures and meaningful concepts of women’s stories about the first childbirth, obtained by their personal experience in the governmental obstetrical system. Narratives of childbirth contain complex knowledge including description of physiological and emotional reactions and characteristics of Russian maternal initiation practices, culminating in the maternity ward. Similar narratives posted on social network and web pages of family portals reveal elements of hypertext and several leading factors of their origin, such as being the consolidation of a new identity through a retrospective autobiographical story, joining the community of motherhood, broadcasting experience to its new members, etc.
Chimpanzees’ (Pan troglodytes) problem-solving skills are influenced by housing facility and captive care duration
Authors: Forss Sofia , Motes-Rodrigo Alba , Hrubesch Christine , Tennie Claudio
Published: November 2020

Although a large body of primate cognition research is done in captive institutions, little is known about how much individuals from different facilities vary in their experiences and cognitive skills. Here we present the results of an experimental study investigating howphysical cognitive skillsvary between chimpanzees in relation to captive settings and their time in captivity. We tested 59 chimpanzees housed at two different captive facilities (a rehabilitation center (sanctuary) and a zoo) in three problem-solving tasks. Our results showed that chimpanzees at the two housing facilities significantly differed in overall task performance. On average, the sanctuary chimpanzees outperformed the chimpanzees housed at the zoo in the detour reaching task and the honey trap task. However, the zoo chimpanzees performed slightly better on average in the learning task. We propose that, for this particular sample, the documented differences result from a combination of factors, such as prior experience with cognitive testing, motivation levels and varying degrees of human exposure. Within the sanctuary sample, we found that chimpanzees who arrived at an earlier age at the sanctuary and had therefore spent a larger percentage of their lives in a captive environment, were better problem-solvers than those that arrived at a later age to the sanctuary. Thus, rehabilitation and time in captivity contributed to improved physical cognitive skills in sanctuary chimpanzees. Our results highlight the importance of studying intraspecific variation and the effect that previous experience and living conditions might have on physical cognitive skills in non-human apes. Accordingly, we should be cautious when extrapolating findings of cognitive studies from one population to the species as a whole.
Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the abyssal plain of the northwestern Pacific Ocean and hadal depths of the Kuril-Kamchatka Trench
Authors: Kamenev Gennady M.
Published: November 2020

The Thyasiridae is the most species-rich family of bivalves in the abyssal and hadal zones of the northwestern Pacific Ocean. In recent years, with at least 14 thyasirid species found in that region at depths exceeding 3,000 m. Some of them are the numerically dominant species in bottom communities. However, all members in that family have not yet been identified to the species level. Based on the material collected from 1953 to 2016 by five deep-sea expeditions, three new species of Thyasiridae (Mollusca: Bivalvia) are described from the abyssal and hadal zones of the northwestern Pacific. “Axinulus” roseus sp. nov. was found in the Kuril-Kamchatka Trench at 9,000–9,583 m depth. This species has a large rhomboidal shell with strong commarginal sculpture, a well defined, long and deep lunule and escutcheon without an auricle, a ctenidium consisting of a single demibranch, extensively lobed lateral pouches, and a large prodissoconch with specific sculpture. It is one of the dominant species in terms of abundance in macrobenthic communities in the deepest basin of the Kuril-Kamchatka Trench with a population density of up to 396 ind. m−2. The species has a shell length of up to 9.0 mm and it is the largest thyasirid with a single demibranch. “Axinulus” oliveri sp. nov. was found in a vast region of the northwestern Pacific on the abyssal plain adjacent to the Kuril-Kamchatka Trench, on the abyssal slope of the Kuril Islands, and in the Kuril-Kamchatka Trench at 4,648–6,168 m depth. This species is characterized by its ovate-rhomboidal shell, a well defined, deep and long escutcheon with a distinct auricle, a ctenidium with a single demibranch, and extensively lobed lateral pouches. It is widespread in the northwestern Pacific and forms populations with a density of up to 36 ind. m−2. Scanning electron microscopic observation of the gills of “A.” roseus sp. nov. and “A.” oliveri sp. nov. revealed that these species are not chemosymbiotic. “Axinulus” roseus sp. nov. and “A.” oliveri sp. nov. are provisionally assigned to the genus Axinulus, because they differ from the type species of the genus in a number of morphological and anatomical features. Parathyasira fragilis sp. nov. was found on the abyssal plain adjacent to the Kuril-Kamchatka Trench at 5,249–5,399 m depth. This species is distinguished by its very thin, fragile, dorsoventrally elongated, rhomboidal shell with very long anterodorsal margin and a long, wide, flat lunule. The taxonomic position of the new species is discussed.
Performance Evaluation of Web Servers using Response Time and Bandwidth
Authors: Tochukwu Nnodi Joy , Emmanuela Chinonye Mary Obasi
Published: November 2020

Computer system performance can be measured using the amount of useful work accomplished by that system when compared to the time and resources utilized. Useful work here means how well the computer is doing the work it is supposed to do. Most websites work under the support of web servers that usually include hardware (for instance CPU, RAM, Disk, and network) as well as software (web services). The alarming growth in web traffic has led to performance problems and has necessitated much research activities as ways to improve web server performance. In this paper, a web server performance evaluation system that evaluates a server based on time of file execution and bandwidth has been designed and developed. Access log data sets from University of Port Harcourt web site were used to study the system and develop software for checking time of server activity in any domain where the application is executed. The evaluation system so designed and developed can be deployed in any server and the values generated can be used in making useful decisions that will mitigate certain occurrences in the future and also offers site owners information that will be useful in forecasting users visiting behaviours and the effects on the server downtime.
Augmented Reality as a Classroom Teaching and Learning Tool: Teachers’ and Students’ Attitude
Authors: Lham Tshering , Jurmey Pema , Tshering Sonam
Published: November 2020

The use of Information Communication and Technology in teaching learning has been emphasized a lot in the recent times as an effective instructional tool and it will only grow and develop further. Augmented Reality is one of the futuristic pedagogy that will offer great opportunities in the incorporation of information technology in teaching and learning. Augmented Reality refers to the introduction of virtual elements in the real world. This will supplement students’ learning through the use of technology. This study assessed the students’ and teachers’ attitude towards the use of Augmented Reality as a learning tool after they experimented and experienced the use of augmented reality through mobile application. For the teachers, a three-hour professional development session on Augmented Reality was conducted. Teachers were taught how to use mobile application to create Augmented Reality. For the students, research team created the Augmented Reality using a mobile application and let students experience it in a biology lesson. After the sessions, their attitudes towards the use of Augmented Reality was assessed through statements of agreement on a 5-point Likert scale. SPSS has been used for statistical analysis. The results show that both the teachers and students have overwhelming support-positive attitude towards the use of Augmented Reality in the classroom teaching and learning.
On the active site of elastase: Partial mapping by means of specific peptide substrates
Authors: Atlas Daphna , Levit S. , Schechter I. , Berger A.
Published: July 2002

RNase‐S peptide as well as some related octa‐ and hexapeptides were found to be highly, reactive substrates of porcine elastase (e.g. Ala4‐Lys‐Phe:

m
= 4500 M−1, k
cat = 32 sec−1, C = 1.4 × 105 M−1 sec−1). Comparison of the various peptides led to the conclusion that the active site of porcine elastase is composed of 6–7 subsites (c.f. [1]). Preliminary mapping shows that subsites S2, S′1 and S′2 have hydrophobic character. Occupation of subsite S4 by the substrate is important for efficient hydrolysis. Binding at this subsite was found to be stereospecific.
Kirromycin‐resistant elongation factor Tu from wild‐type of Lactobacillus brevis
Authors: Wörner Walter , Wolf Heinz
Published: July 2002

Properties of the elongation factor Tu from Lactobacillus brevis which is naturally insensitive to kirromycin are described. The protein is characterized by an unusual nucleotide‐binding site with increased affinity for GTP and extreme heat stability. EF‐Tu is sensitive to pulvomycin in the assay of polyphenylalanine synthesis. However, the failure of the protein to display pulvomycin‐dependent GDP‐binding and GTPase activity indicates that pulvomycin action in L. brevis differs from that in E. coli.
Exclusive occurrence of thermogenin antigen in brown adipose tissue
Authors: Cannon Barbara , Hedin Anders , Nedergaard Jan
Published: July 2002

Thermogenin is the purine‐nucleotide binding polypeptide in brown adipose tissue mitochondria (M
r 32 000) which confers upon these mitochondria the ability to produce heat. An enzyme‐linked immunosorbent assay (ELISA) has been developed to demonstrate and quantitate the occurrence of thermogenin antigen in small amounts of tissue, and thus to characterize different depots of fat tissue as white or brown. The extreme sensitivity of the method allows determination of thermogenin in samples equivalent to <1 mg tissue. The results indicate that thermogenin seems to be exclusively localised in brown fat mitochondria (as compared to white fat, liver or heart muscle mitochondria), and thermogenin antigen could only be found in brown adipocytes (as compared to white adipocytes). Thus, brown and white adipose tissue are probably ontogenetically different
Control of tubulin and actin gene expression in Tetrahymena pyriformis during the cell cycle
Authors: Zimmerman A.M. , Zimmerman S. , Thomas J. , Ginzburg I.
Published: July 2002

Poly(A)‐containing mRNA was isolated from division synchronized populations of the ciliated protozoan, Tetrahymena pyriformis. The level of tubulin and actin mRNA at specific cell cycle stages was analyzed by hybridization to tubulin and actin cDNA probes and by gel analysis of their in vitro translation products. The pattern of fluctuation of tubulin mRNA level was similar to that observed for the in vivo tubulin synthesis previously reported [1]. This suggest that as the cell progress through the cell cycle, tubulin synthesis is controlled at the mRNA level. There was little fluctuation of actin synthesis or actin mRNA levels during the cell cycle, which may be indicative of a different regulatory mechanism for actin than for tubulin.
Two distinct proton translocating ATPases are present in membrane vesicles from radish seedlings
Authors: de Michelis M.I. , Pugliarello M.C. , Rasi-Caldogno F.
Published: July 2002

Two distinct systems of Mg‐ATP‐dependent transport of protons have been put in evidence in microsomal vesicles from radish seedlings by investigating the effects of vanadate and of NO−
3 on the initial rate of acridine orange accumulation. One system is vanadate‐resistant and is inhibited by NO−
3 (I
50 1.3 mM), the other is inhibited by vanadate (I
50 43 μM) and unaffected by NO−
3. The two systems differently distribute along a continuous sucrose density gradient: the NO−
3‐sensitive system of Mg‐ATP‐dependent transport of protons peaks at d = 1.13–1.14, while the vanadate‐sensitive one peaks at d = 1.16–1.17.
Phosphorylation site sequence of smooth muscle myosin light chain (Mr = 20 000)
Authors: Pearson R.B. , Jakes R. , John M. , Kendrick-Jones J. , Kemp B.E.
Published: July 2002

The amino terminal sequence of the myosin light chain (M
r = 20 000) isolated from chicken gizzards was found to be acetyl‐Ser‐Ser‐Lys‐Arg‐Ala‐Lys‐Ala‐Lys‐Thr‐Thr‐Lys‐Lys‐Arg‐Pro‐Gln‐Arg‐Ala‐Thr‐Ser(P)‐Asn‐Val‐Phe. This sequence assignment differs from that reported by Maita et al. [(1981) European J. Biochem. 117, 417] in the order of the tryptic peptides. The revised amino acid sequence exhibits greater homology with the phosphorylation site sequences of the regulatory light chains from cardiac and skeletal muscle. Moreover it is now apparent why synthetic peptides corresponding to the previously reported sequence were very poor substrates for the myosin light chain kinase.
Inhibition of glucagon‐stimulated hepatic glycogenolysis by E‐series prostaglandins
Authors: Brass Eric P. , Garrity Maureen J. , Robertson R.Paul
Published: July 2002

The effect of E‐series prostaglandins (PGE) on hepatic glucose metabolism is controversial. This study uses isolated rat hepatocytes and exogenously added PGE analogs or frequent native PGE additions (to compensate for hepatic PGE degradation) to define PGE's effect on hepatic glycogenolysis. 16,16‐Dimethyl PGE2, 15(S),15‐methyl PGE2, PGE1 and PGE2 all inhibit glucagon‐stimulated glycogenolysis. It is concluded that E‐series prostaglandins can act directly on the liver to inhibit glycogenolysis.
Dual effects of glucose on the cytosolic Ca2+ activity of mouse pancreatic β‐cells
Authors: Rorsman P. , Abrahamsson H. , Gylfe E. , Hellman Bo
Published: July 2002

The cytosolic Ca2+ activity of mouse pancreatic β‐cells was studied with the intracellular fluorescent indicator quin2. When the extracellular Ca2+ concentration was 1.20 mM, the basal cytosolic Ca2+ activity was 162 ± 9 nM. Stimulation with 20 mM glucose increased this Ca2+ activity by 40%. In the presence of only 0.20 mM Ca2+ or after the addition of the voltage‐dependent Ca2+‐channel blocker D‐600, glucose had an opposite and more prompt effect in reducing cytosolic Ca2+ by about 15%. It is concluded that an early result of glucose exposure is a lowering of the cytosolic Ca2+ activity and that this effect tends to be masked by a subsequent increase of the Ca2+ activity due to influx of Ca2+ through the voltage‐dependent Ca2+ channels.
31P‐NMR studies of Mycoplasma gallisepticum cells using a continuous perfusion technique
Authors: Egan William , Barile Michael , Rottem Shlomo
Published: July 2002

31P‐NMR studies of Mycoplasma gallisepticum cells have been carried out using a continuous perfusion technique; these are the first such studies with this organism. Using this technique, glucose metabolism was monitored in the intact organisms, and cell extracts were prepared to identify the intermediates. Under glycolytic conditions, high levels of fructose‐1,6‐diphosphate were observed, indicating that this sugar may play a key role in the regulation of metabolism. The level of phosphoenolpyruvate was low under normal glycolytic conditions, and did not increase during starvation. From the position of the internal inorganic phosphate peak, the intracellular pH was estimated. The cells were found to maintain an intracellular pH of ~ 7.1 over an investigated external pH range of 6.6–8.6.
1,25‐Dihydroxyvitamin D3 enhances prostaglandin E2 production by monocytes
Authors: Koren R. , Ravid A. , Rotem C. , Shohami E. , Liberman U.A. , Novogrodsky A.
Published: July 2002

Partial removal of monocytes from human peripheral blood mononuclear cells, or the addition of indomethacin. reduced the antiproliferative effect of 1,25(OH)2D3 on mitogen‐stimulated mononuclear cells. Addition of 1,25(OH)2D3 (1nM) to mitogen‐stimulated mononuclear cells caused a 2–4‐fold increase in prostaglandin E2 production during the second day of culture. The inhibitory effect of 1,25(OH)2D3 on lymphocyte proliferation is greatly augmented up to 7‐fold in the presence of prostaglandin E2. We conclude that monocytes are involved in the inhibitory effect of 1,25(OH)2D3 on the mitogenic stimulation of human lymphocytes and that their action is probably mediated by prostaglandins.
A 1H spin echo NMR study of the HeLa tumour cell
Authors: Reglinski J. , Smith W.E. , Suckling C.J. , Al-Kabban M. , Watson I.D. , Stewart M.J.
Published: July 2002

Phosphorylcholine, phosphorylcreatine, lactate, glutathione, glycine and leucine were identified in living HeLa cells in the first study of this cell type by 1H spin echo NMR spectroscopy. The technique has the advantage that it is non‐invasive, providing detailed structural information on individual species present in the cell matrix. It has been used in this case to study the rate of energy consumption following the activation of the glycolytic pathway with glucose.
The effect of cadmium ions on 2,3‐bisphosphoglycerate in erythrocytes studied with 31P NMR
Authors: Arkowitz Robert , Hoehn-Berlage Mathias , Gersonde Klaus
Published: July 2002

The interaction of cadmium ions with human red blood cell (RBC) 2,3‐bisphosphoglycerate (DPG) was studied by 31P NMR. 31P NMR spectra and 31P T
1 and 31P T
2 relaxation times give evidence for cadmium‐2,3‐bisphosphoglycerate complexation in aqueous solution . 31P NMR spectra indicate the occurrence of a similar complexation in RBC cryolysates. The lag phase (constant polyphosphate level) prior to DPG hydrolysis in incubated red blood cells is lengthened in the presence of cadmium.
Crystallization and preliminary X‐ray diffraction studies of intact EF‐Tu from Thermus aquaticus YT‐1
Authors: Lippmann Corinna , Betzel Christian , Dauter Zbyszek , Wilson Keith , Erdmann Volker A.
Published: July 2002

Many attempts have been made to elucidate the three‐dimensional structure from elongation factor Tu, but so far the only crystals suitable for X‐ray crystallography contained a partially degraded protein. Here, we report the crystallization of a fully active, intact EF‐Tu from Thermus aquaticus. The crystals belong to hexagonal space group P6322 and diffract up to 2.6 Å. The cell dimensions are a = b = 178 Å, c = 238 Å and 6 molecules are contained per asymmetric unit.
Binding and receptor down‐regulation of a novel vasoconstrictor endothelin in cultured rat vascular smooth muscle cells
Authors: Hirata Yukio , Yoshimi Hiroki , Takaichi Shigeko , Yanagisawa Masashi , Masaki Tomoh
Published: July 2002

Binding of a novel endothelium‐derived vasoconstrictor endothelin (ET) and the regulation of its receptor were studied in cultured rat vascular smooth muscle cells. 125I‐labeled‐ET bound to the cells was resistant to acid extraction and the majority of the acid‐resistant compartment was extractable with chloroform/methanol with minimal degradation. Autoradiographic studies using electron microscopy revealed that the grains were predominantly localized in the plasma membranes, but some were adjacent to and within the lysosome. Pretreatment with ET resulted in a substantial reduction of ET receptor number without changing its binding affinity. ET‐induced increase in cytosolic free Ca2+ levels ([Ca2+]i] was absent or attenuated in the ET‐pretreated cells. These data suggest that tight association of ET with its receptor is due to a strong interaction of its hydrophobic domain with the membrane lipids and/or its internalization within cells and that down‐regulation of ET receptor is functionally linked to decreased ET‐induced [Ca2+]i response.
Heparin inhibits IP3‐induced Ca2+ release in permeabilized pancreatic β‐cells
Authors: Nilsson Thomas , Zwiller Jean , Boynton Alton L. , Berggren Per-Olof
Published: July 2002

Heparin was found to inhibit the Ca2+ release induced by inositol 1,4,5‐trisphosphate (IP3) in permeabilized pancreatic β‐cells obtained from obese hyperglycemic mice. The effect of heparin was dose‐dependent and not due to inhibition of Ca2+ uptake into the IP3‐sensitive pool. The effect appeared specific for heparin and was not reproduced by other polysaccharides such as chondroitin sulfates. Heparin might consequently be a useful tool when investigating the molecular mechanism whereby IP3 mobilizes Ca2+.
Engineering of an intersubunit disulphide bridge in glutathione reductase from Escherichia coli
Authors: Scrutton Nigel S. , Berry Alan , Perham Richard N.
Published: July 2002

By site‐directed mutagenesis, Thr‐75 was converted to Cys‐75 in the glutathione reductase (EC 1.6.4.2 of Escherichia coli. This led to the spontaneous formation of an intersubunit disulphide bridge across the 2‐fold axis of the dimeric enzyme. The disulphide bridge had no deleterious effect on the catalytic activity, but nor did it increase the thermal stability of the enzyme, possibly because of local conformational flexibility on the dimer interface. The T75C mutant, like the wild‐type enzyme, was inactivated by NADPH, proving that this inactivation cannot be due to simple dissociation of the dimer.
Lateral mobility of proteins and lipids in the red cell membrane and the activation of adenylate cyclase by β‐adrenergic receptors
Authors: Peters Reiner
Published: July 2002

Models of β‐adrenergic signal transduction in red blood cell membranes frequently assume that at least one of the membrane‐bound components is laterally mobile and distributes the hormonal signal in the membrane plane. However, direct measurements reveal that protein lateral mobility in the red cell membrane is severely restricted. Furthermore, the spectrin‐actin skeleton compartmentalizes the cytoplasmic face of the red cell membrane into a regular array of small elementary areas. These considerations support models in which the β‐adrenergic signal is spread in the membrane plane by a molecule which has binding sites on the membrane but diffuses in the aqueous compartment.
Protoporphyrinogen oxidase inhibition by three peroxidizing herbicides: Oxadiazon, LS 82‐556 and M&B 39279
Authors: Matringe Michel , Camadro Jean-Michel , Labbe Pierre , Scalla René
Published: July 2002

Three chemically unrelated peroxidizing molecules, namely oxadiazon [5‐(t‐butyl)‐3‐(2,4‐dichloro‐5‐isopropoxyphenyl)‐1,3,4‐oxadiazol‐2‐one], LS 82‐556 [(S)3‐N‐(methylbenzyl)carbamoyl‐5‐propionyl‐2,6‐lutidine] and M&B 39279 [5‐amino‐4‐cyano‐1‐(2,6‐dichloro‐4‐trifluoromethylphenyl)pyrazol], are potent inhibitors of plant, yeast and mouse protoporphyrinogen oxidase.
The amino‐terminal sequences in the pro‐α and ‐β polypeptides of human lysosomal β‐hexosaminidase A and B are retained in the mature isozymes
Authors: Hubbes Martin , Callahan John , Gravel Roy , Mahuran Don
Published: July 2002

The α‐ and β‐subunits of β‐hexosaminidase (β‐N‐acetylhexosaminidase, EC 3.2.1.52) are synthesized in the rough endoplasmic reticulum as prepropolypeptides. After the loss of the signal peptide and formation of enzymatically active dimers, the pro‐isoenzymes are transported through the Golgi and into the lysosome for proteolytic and glycolytic processing to their stable mature forms. Maturation includes the hydrolysis, and previously presumed loss, of small N‐terminal peptides from each propolypeptide. A recent report characterizing the processing of the β‐prepropolypeptide in β‐hexosaminidase from a human fibroblast cell line [(1989) J. Biol. Chem. 264, 3380–3384] reported that the small pro‐β peptide was retained through a disulfide bond in the mature subunit, and that it was glycosylated. We have confirmed this result in normal human tissue. However, we report a different N‐terminal for the mature pro‐β peptide. Furthermore, we have found that the pro‐α peptide is similarly retained in the mature α‐subunit through its single cysteine residue and that each pro‐peptide undergoes C‐terminal processing.
The cooperativity phenomena in a pigment‐protein complex of light‐harvesting antenna revealed by picosecond absorbance difference spectroscopy
Authors: Danielius R.V. , Mineyev A.P. , Razjivin A.P.
Published: July 2002

A model of the cooperative changes in optical properties of light‐harvesting bacteriochlorophyll molecules of complex B890 in response to the absorption of light quanta is proposed. According to the model, each antenna chromophore may persist in either of two optically non‐excited states, R and T. The occurrence of at least one excitation per complex causes all optically non‐excited chromophores of the complex to be converted from state R to state T. The theory is shown to be in good agreement with experimental ‘light curves’ (ΔAvs intensity of picosecond excitation pulse) for the ‘minor’ and ‘major’ signals of light‐harvesting bacteriochlorophylls of complex B890 from Chromatium minutissimum.
A common structural motif in thiamin pyrophosphate‐binding enzymes
Authors: Hawkins Christopher F. , Borges Adolfo , Perham Richard N.
Published: July 2002

The amino acid sequences of a wide range of enzymes that utilize thiamin pyrophosphate (TPP) as cofactor have been compared. A common sequence motif approximately 30 residues in length was detected, beginning with the highly conserved sequence ‐GDG‐ and concluding with the highly conserved sequence ‐NN‐. Secondary structure predictions suggest that the motif may adopt a βαβ fold. The same motif was recognised in the primary structure of a protein deduced from the DNA sequence of a hitherto unassigned open reading frame of Rhodobacter capsulata. This putative protein exhibits additional homology with some but not all of the TPP‐binding enzymes.
Molecular cloning and sequence determination of a cDNA coding for the α‐subunit of a Go‐type protein of Xenopus laevis oocytes
Authors: Olate Juan , Jorquera Hugo , Purcell Patricia , Codina Juan , Birnbaumer Lutz , Allende Jorge E.
Published: July 2002

Xenopus laevis oocytes are cells ideally suited to the study of signal transduction and of the G‐proteins that are involved in this process. A X. laevis cDNA library in λgt10 has been screened with a mixture of three oligonucleotide probes designed to detect sequences found in various mammalian α‐subunits of G‐proteins. One of these clones has been purified through tertiary screening and the DNA insert has been sequenced. This clone was found to include the total sequence coding for a 354 amino acid protein that is 89% identical to the sequence of α‐subunit of rat Go. The differences with the mammalian protein were clustered in amino acids 290–315, which have been postulated to define the region interacting with the receptor and effector molecule. The homology with the α‐subunits of other mammalian G‐proteins is lower (65–70% to Gi and 42% to Gs). On this basis, this clone can be classified as Go‐like.
Tumor promoter 12‐O‐tetradecanoylphorbol 13‐acetate inhibits mas/angiotensin receptor‐stimulated inositol phosphate production and intracellular Ca2+ elevation in the 401L‐C3 neuronal cell line
Authors: Jackson Trevor R. , Hanley Michael R.
Published: July 2002

Stimulation of mas‐oncogene transfected 401L‐C3 cells by angiotensins leads to the production of inositol phosphates. This response shows dose dependence, and has an apparent rank order of potency angiotensin III ⩾ angiotensin II ⪢ angiotensin I. Preincubation with 12‐O‐tetradecanoylphorbol 13‐acetate, for 5 min, significantly diminishes both inositol phosphate and intracellular [Ca2+] responses to angiotensins, without affecting those stimulated by the endogenous bradykinin receptor. Incubation of 401L‐C3 cells with either phorbol ester or angiotensins leads to elevation of intracellular pH, implying that mas/angiotensin receptor stimulation itself leads to protein kinase C activation. These results suggest the operation of a negative feedback loop specific for the mas/angiotensin receptor signalling pathway, and which may be essential in defining the final biological output response to this receptor stimulation.
A luminescence probe for metallothionein in liver tissue: emission intensity measured directly from copper metallothionein induced in rat liver
Authors: Stillman Martin J. , Gasyna Zbigniew , Zelazowski Andrzej J.
Published: July 2002

We report the first use of an emission probe based on the Cu(I)‐thiolate chromophore, for the direct observation of copper metallothionein located in samples of rat liver. Elevated synthesis of Cu‐MT in the rat liver was induced by subcutaneous injections of a series of aqueous CuCl2 solutions containing increasing amounts of Cu(II). Luminescence intensity in the 600 nm region, detected from frozen solutions of Cu‐MT and from slices of the liver frozen at 77 K, following excitation in the 300 nm region, was dependent on the concentration of the Cu(II) used in the inducing solution. No such luminescence intensity was found for control samples obtained from the livers of rats not exposed to copper salts. It is suggested that this new method will allow direct visualization of Cu‐MT in tissue where genetic disorders impare copper metabolism.
Evidence for the identity of glutathione‐dependent formaldehyde dehydrogenase and class III alcohol dehydrogenase
Authors: Koivusalo Martti , Baumann Marc , Uotila Lasse
Published: July 2002

Formaldehyde dehydrogenase; Alcohol dehydrogenase, class III; Sequence homology; Amino acid sequence
Identification of the Arg‐Gly‐Asp sequence in laminin A chain as a latent cell‐binding site being exposed in fragment P1
Authors: Aumailley Monique , Gerl Martin , Sonnenberg Amoud , Deutzmann Rainer , Timpl Rupert
Published: July 2002

A single RGD‐containing sequence present within an epidermal growth factor‐like repeat of the short arms of laminin is shown by peptide inhibition to block integrin receptors recognizing a latent cell‐binding site of laminin. Based on proteolysis data it is proposed that masking occurs by folding of the globular domain IVa over the cell‐binding site in the adjacent rod‐like structures of laminin A chain.
Sequence of a novel carbonic anhydrase‐related polypeptide and its exclusive presence in purkinje cells
Authors: Kato Kikuya
Published: July 2002

I isolated a mouse cDNA clone encoding a novel polypeptide which has strong homology with carbonic anhydrase. Unlike the other carbonic anhydrases, it has an additional N‐terminal domain with a glutamic acid stretch and an arginine substitutes one of the three histidine residues which bind zinc ion. In the central nervous system, carbonic anhydrase is known to be expressed only in glia cells, but this gene is expressed in neuron, but only in Purkinje cells.
A mitochondrial protein fraction catalyzing transport of the K+ analog Tl+
Authors: Diwan Joyce Johnson , Paliwal Ranjana , Kaftan Edward , Bawa Raj
Published: July 2002

A protein fraction has been obtained from detergent‐solubilized mitochondrial membranes by its affinity for quinine, an inhibitor of K+ transport. A peptide derived from the predominant 53 kDa protein in this fraction is found to be identical in sequence to a portion of aldehyde dehydrogenase. Antigenically unrelated bands at 97, 77, 57, and 31 kDa are also seen on polyacrylamide gels. Observations utilizing a fluorescent probe entrapped in the lumen of membrane vesicles indicate that the reconstituted protein fraction imparts permeability to the K+ analog Tl+. These and other findings suggest that the affinity purified fraction includes a cation transport catalyst.