bluuebunny/crossref_metadata_2025 huggingface dataset:
Activated T Lymphocytes in Pre‐Eclampsia
Authors: Darmochwal‐Kolarz D. , Saito S. , Rolinski J. , Tabarkiewicz J. , Kolarz B. , Leszczynska‐Gorzelak B. , Oleszczuk J.
Published: June 2007

Problem

The aim of our study was to investigate the activation markets of T CD3+, T helper CD4+ and T cytotoxic CD8+ cells, as well as, the populations of T naïve CD4+ CD45RA+, T memory CD4+ CD45RO+ and T regulatory lymphocytes in PE and healthy pregnant women.

Method of study

Twenty‐five patients with PE and thirty healthy third trimester pregnant women were included in the study. Peripheral blood mononuclear cells were isolated from peripheral blood, stained with monoclonal antibodies and estimated using the flow cytometric method.

Results

The percentages of CD4+CD25+, CD4+CD25dim, CD3+HLA‐DR+, CD4+HLA‐DR+ and CD8+HLA‐DR+ cells did not differ between study groups. The population of T regulatory CD4+CD25bright lymphocytes was significantly lower in the group of patients with PE when compared with the controls (P < 0.01). The percentages of CD3+CD25+ (P < 0.05), CD8+CD25+ (P < 0.05), CD4+45RO+ (P < 0.01) lymphocytes were significantly higher, while CD4+CD45RA+ (P < 0.01) cells – significantly lower in peripheral blood of patients with PE when compared with the control group.

Conclusion

The increased levels of T CD4+45RO+ and T CD8+ CD25+ cells can suggest the activation of CD4+ and CD8+ T lymphocytes in pre‐eclampsia. It seems possible that the activation of T lymphocytes is associated with the deficiency of T regulatory cells in PE.
RCAS1 Decidual Immunoreactivity During Placental Abruption: Immune Cell Presence and Activity
Authors: Wicherek Lukasz , Galazka Krystyna , Lazar Agata
Published: June 2007

Problem

RCAS1 is a protein responsible for the suppression of cytotoxic immune response during gestation. The present study evaluates the immunoreactivity level of RCAS1 with respect to immune cell status during placental abruption (PA) and retained placental tissue (RPT).

Method of study

RCAS1, CD3, CD56, CD69 and CD25 immunoreactivity was assessed by immunohistochemistry in 66 decidual samples derived from PA and from RPT.

Results

RCAS1 immunoreactivity was statistically significantly higher in decidual tissue samples derived from patients with RPT than in those derived from patients with PA. A statistically significantly lower number of CD56+ and CD3+ cells and immunoreactivity level of CD69 were found in patients with RPT, compared to those with PA.

Conclusion

Placental abruption seems to be associated with excessive accumulation and activity of CD3+ and CD56+ cells in decidua, which processes might, in turn, result from an insufficient RCAS1 decidual level.
Maternal Serum Interleukin‐10, Interleukin‐2 and Interleukin‐6 in Pre‐Eclampsia and Eclampsia
Authors: Borekci Bunyamin , Aksoy Hulya , Al Ragip Atakan , Demircan Berna , Kadanali Sedat
Published: June 2007

Problem

The aim of the study was to investigate and compare the concentrations of interleukin (IL)‐2, IL‐6, and IL‐10 in serum of women with mild pre‐eclampsia, severe pre‐eclampsia, eclampsia, and normotensive pregnancy.

Method of study

A total of 69 consecutive cases, 38 mild pre‐eclampsia, 20 severe pre‐eclampsia, 11 eclampsia, and 20 normotensive controls were included in this study. Serum IL‐2, IL‐6, and IL‐10 levels were determined using enzyme‐linked immunosorbent assay method.

Results

Gestational age (P = 0.210) and body mass index (P = 0.214) between the groups were similar. The mean concentration of serum IL‐2 and IL‐6 were not different between the groups (P = 0.261, P = 0.141 respectively). The median concentrations of serum IL‐10 in patients with mild and severe pre‐eclampsia were similar (P < 0.282) and was significantly lower than those of controls (P < 0.001) and patients with eclampsia (P < 0.001). In patients with eclampsia, the median concentration of IL‐10 was significantly higher than that of all other groups (P < 0.001 for each comparison).

Conclusion

Pre‐eclampsia is associated with a deficiency serum IL‐10. High serum IL‐10 is correlated with the presence of eclampsia.
Expression and characterization of recombinant 2′,5′‐oligoadenylate synthetase from the marine sponge Geodia cydonium
Authors: Päri Mailis , Kuusksalu Anne , Lopp Annika , Reintamm Tõnu , Justesen Just , Kelve Merike
Published: June 2007

2′,5′‐oligoadenylate (2‐5A) synthetases are known as components of the interferon‐induced cellular defence mechanism in mammals. The existence of 2‐5A synthetases in the evolutionarily lowest multicellular animals, the marine sponges, has been demonstrated and the respective candidate genes from Geodia cydonium and Suberites domuncula have been identified. In the present study, the putative 2‐5A synthetase cDNA from G. cydonium was expressed in an Escherichia coli expression system to characterize the enzymatic activity of the recombinant polypeptide. Our studies reveal that, unlike the porcine recombinant 2‐5A synthetase, the sponge recombinant protein associates strongly with RNA from E. coli, forming a heterogeneous set of complexes. No complete dissociation of the complex occurs during purification of the recombinant protein and the RNA constituent is partially protected from RNase degradation. We demonstrate that the sponge recombinant 2‐5A synthetase in complex with E. coli RNA catalyzes the synthesis of 2′,5′‐phosphodiester‐linked 5′‐triphosphorylated oligoadenylates from ATP, although with a low specific activity. Poly(I)·poly(C), an efficient artificial activator of the mammalian 2‐5A synthetases, has only a minimal effect (an approximate two‐fold increase) on the sponge recombinant 2‐5A synthetase/bacterial RNA complex activity.
Studies of the ATPase activity of the ABC protein SUR1
Authors: de Wet Heidi , Mikhailov Michael V. , Fotinou Constantina , Dreger Mathias , Craig Tim J. , Vénien‐Bryan Catherine , Ashcroft Frances M.
Published: June 2007

The ATP‐sensitive potassium (KATP) channel couples glucose metabolism to insulin secretion in pancreatic β‐cells. It comprises regulatory sulfonylurea receptor 1 and pore‐forming Kir6.2 subunits. Binding and/or hydrolysis of Mg‐nucleotides at the nucleotide‐binding domains of sulfonylurea receptor 1 stimulates channel opening and leads to membrane hyperpolarization and inhibition of insulin secretion. We report here the first purification and functional characterization of sulfonylurea receptor 1. We also compared the ATPase activity of sulfonylurea receptor 1 with that of the isolated nucleotide‐binding domains (fused to maltose‐binding protein to improve solubility). Electron microscopy showed that nucleotide‐binding domains purified as ring‐like complexes corresponding to ∼ 8 momomers. The ATPase activities expressed as maximal turnover rate [in nmol Pi·s−1·(nmol protein)−1] were 0.03, 0.03, 0.13 and 0.08 for sulfonylurea receptor 1, nucleotide‐binding domain 1, nucleotide‐binding domain 2 and a mixture of nucleotide‐binding domain 1 and nucleotide‐binding domain 2, respectively. Corresponding Km values (in mm) were 0.1, 0.6, 0.65 and 0.56, respectively. Thus sulfonylurea receptor 1 has a lower Km than either of the isolated nucleotide‐binding domains, and a lower maximal turnover rate than nucleotide‐binding domain 2. Similar results were found with GTP, but the Km values were lower. Mutation of the Walker A lysine in nucleotide‐binding domain 1 (K719A) or nucleotide‐binding domain 2 (K1385M) inhibited the ATPase activity of sulfonylurea receptor 1 by 60% and 80%, respectively. Beryllium fluoride (Ki 16 µm), but not MgADP, inhibited the ATPase activity of sulfonylurea receptor 1. In contrast, both MgADP and beryllium fluoride inhibited the ATPase activity of the nucleotide‐binding domains. These data demonstrate that the ATPase activity of sulfonylurea receptor 1 differs from that of the isolated nucleotide‐binding domains, suggesting that the transmembrane domains may influence the activity of the protein.
Cricoid pressure: Assessment of performance and effect of training in emergency department staff
Authors: Quigley Paul , Jeffrey Penelope
Published: June 2007

Objectives:  (i) To evaluate the theoretical knowledge and practical skills of ED staff regarding the technique of cricoid pressure; (ii) to assess the efficacy of two methods of cricoid pressure training.

Methods:  Theoretical knowledge of participants was assessed by a pretraining questionnaire, and practical ability was assessed using a Flinders Meditech cricoid pressure trainer. Participants then received a brief period of theoretical instruction, and were allocated to two training groups. Group A received further training with the pressure trainer. Group B was provided with reading material. Practical ability was assessed again immediately and then 4–6 weeks later.

Results:  Seventy subjects were recruited. A total of 53% could identify the position of the cricoid cartilage, and 16% could identify the pressure required. The percentage achieving a correct position at baseline, immediately after training and after 4–6 weeks was 47%, 97% and 70% respectively in group A, compared with 61%, 86% and 74% respectively in group B, a non‐significant difference between groups. The percentage achieving correct pressure at baseline, immediately after training and 4–6 weeks later was 38%, 88% and 67% respectively in group A, compared with 30%, 33% and 51% respectively in group B. The between‐group difference was significant only immediately following training (P < 0.0001).

Conclusion:  Theoretical knowledge and technique regarding cricoid pressure was poor among our ED staff. Both methods of training appeared to improve performance. The biofeedback group was more likely to apply correct pressure immediately after training. The effects of training diminished rapidly with time.
Which heparin during the investigation of chest pain at term pregnancy?
Authors: Boyle Rhonda K
Published: June 2007

A patient was treated with a therapeutic dose of low‐molecular‐weight heparin, then required caesarean section immediately following its administration. Reasons for preferring this heparin over unfractionated heparin are acknowledged but not supported for short‐term use in an obstetric patient near term.
Abdominal pain and jaundice: Appendiceal perforation an important differential
Authors: Dawes Tim , Burrows Cameron
Published: June 2007

Clinicians must be aware of atypical presentations of common conditions. Appendiceal perforation with peritonitis and sepsis presenting with cholestatic jaundice is an important example, given the prevalence of the condition and the mortality associated with delayed diagnosis. The authors describe a case seen at their hospital.
The shapes of molecular cloud cores in Orion
Authors: Tassis Konstantinos
Published: June 2007

We investigate the intrinsic shapes of starless cores in the Orion giant molecular cloud, using the pre-stellar core sample of Nutter & Ward-Thompson, which is based on submillimetre SCUBA data. We employ a maximum-likelihood method to reconstruct the intrinsic distribution of ellipsoid axial ratios from observations of the axial ratios of projected plane-of-the-sky core ellipses. We find that, independently of the details of the assumed functional form of the distribution, there is a strong preference for oblate cores of finite thickness. Cores with varying finite degrees of triaxiality are a better fit than purely axisymmetric cores, although cores close to axisymmetry are not excluded by the data. The incidence of prolate starless cores in Orion is found to be very infrequent. We also test the consistency of the observed data with a uniform distribution of intrinsic shapes, where oblate and prolate cores of all degrees of triaxiality occur with equal probability. Such a distribution is excluded at the 0.1 per cent level. These findings have important implications for theories of core formation within molecular clouds.
TYC 1031 01262 1: the first known Galactic eclipsing binary with a Type II Cepheid component
Authors: Antipin S. V. , Sokolovsky K. V. , Ignatieva T. I.
Published: June 2007

We present the discovery and CCD observations of the first eclipsing binary with a Type II Cepheid component in our Galaxy. The pulsation and orbital periods are found to be 4.1523 and 51.38 d, respectively, i.e. this variable is the system with the shortest orbital period among known Cepheid binaries. Pulsations dominate the brightness variations. The eclipses are assumed to be partial. The EB-subtype eclipsing light curve leads us to believe that the binary components are non-spherical.
Retention of Physician Assistants in Rural Health Clinics
Authors: Henry Lisa R. , Hooker Roderick S.
Published: June 2007

ABSTRACT: 
Context:

Improvement of rural health care access has been a guiding principle of federal and state policy regarding physician assistants (PAs).

Purpose:

To determine the factors that influence autonomous rural PAs (who work less than 8 hours per week with their supervising physician) to remain in remote locations.

Methods:

A qualitative exploratory study was undertaken in 8 rural Texas towns, including direct observation of clinics, semi‐structured interviews with PAs, and focus groups with community residents.

Findings:

The major factors contributing to retention among autonomous rural PAs include: confidence in the ability to provide adequate health care, desire for small‐town life, residing in the community, and being involved with the community. Both PAs and residents thought the level of their town's health care was moderately good but could be improved. The clinic allowed easy access for primary care and minor injuries. Town residents and PAs also expressed a desire for major improvements including a pharmacy, visiting specialists, and additional medical equipment. Not all residents sought medical care at the clinic, with some electing to travel to physicians in larger towns.

Conclusions:

Rural community residents have more confidence in and satisfaction with PAs who have remained in a clinic for several years. In order to increase retention rates, PAs committed to autonomous, rural primary care would benefit from additional training, particularly in emergency medicine, the benefits of community involvement, and adaptation to the local culture.
Differential Effects of Economic Factors on Specialist and Family Physician Distribution in Illinois: A County‐Level Analysis
Authors: Mistretta Martin J.
Published: June 2007

ABSTRACT: 
Context:

Uneven distribution of physicians across geographic areas of the United States remains a significant problem that may have implications for health.

Purpose:

To develop a statistical model of physician distribution in Illinois counties that predicts where specialists and family physicians practice, and to suggest policy strategies for alleviating shortages.

Methods:

Three‐stage least squares, an estimation technique, was utilized to create a model where 19 variables suggested by the literature predicted specialist and family physician distribution within geographic areas, specifically counties in Illinois.

Findings:

Non‐economic quality of life factors seemed to be related to specialist physician practice location (eg, percent graduates and professionals located in the area, public school expenditures, nonpublic teachers per capita, and sufficient hospital beds). In contrast, economic factors were related to family physician practice location (eg, per capita income, total population [an indicator of demand for medical care]).

Conclusion:

Indicators suggest quality of life factors appear important in specialist location and retention, whereas indicators suggest economic factors appear important to family physician location and retention. Subsidies are suggested to encourage more family physicians to locate and remain in rural areas.
Physician Perceptions of Practice Environment and Professional Satisfaction in California: From Urban to Rural
Authors: Luman Kyle , Zweifler John , Grumbach Kevin
Published: June 2007

ABSTRACT: Context: Few studies have systematically examined the experience of rural practice from the physician's perspective or included physicians from an array of specialties, particularly non‐primary care.Purpose:To better understand differences between rural and urban physicians in perceptions of their practice environment.Methods:In 2001‐2002, self‐administered questionnaires were sent to a probability sample of primary care and specialist physicians identified from the American Medical Association's Physician masterfile in California. Logistic regression was performed to model the effect practice location had on key variables, controlling for physician demographics, specialty, and the insurance profile of the physician's patients.Findings:Completed questionnaires were obtained from 1,365 of 2,240 eligible urban physicians (61%), and 398 of 632 rural physicians (63%). Among primary care physicians, those in rural areas defined as nonadjacent or small non‐metropolitan counties were the least likely to report pressures to see more patients, limit referrals, and limit treatment options. In contrast, among specialists, those in rural areas within metropolitan areas (or in large adjacent non‐metropolitan counties) were more likely than urban specialists to report practice pressures. Although rural physicians in both primary care and specialist fields were more likely than urban physicians to report difficulty attracting new physicians to their communities, they perceived their overall practice climate to be better. Physicians in the nonadjacent‐or‐small non‐metropolitan category were the most satisfied, but specialists in the nonadjacent‐or‐small non‐metropolitan category were the least satisfied.Conclusion:Physicians in rural California appear to have maintained a greater sense of clinical autonomy and higher professional satisfaction compared with their urban counterparts.
Rurality and Ethnicity in Adolescent Physical Illness: Are Children of the Growing Rural Latino Population at Excess Health Risk?
Authors: Wickrama K. A. S. , Elder Glen H. , Todd Abraham W.
Published: June 2007

ABSTRACT: Context and Purpose:This study's objectives are to: investigate potential additive and multiplicative influences of rurality and race/ethnicity on chronic physical illness in a nationally representative sample of youth; and examine intra‐Latino processes using a Latino sub‐sample. Specifically, we examine how rurality and individual psychosocial processes reflected by acculturation proxies (generational status and use of the English language at home) link to chronic physical illness of Latino youth. Finally, we examine whether these associations and the levels of chronic illness differ across Latino subgroups.Methods:Logistic‐normal (binomial) modeling analyses examine multilevel influences on physical health using longitudinal data from a nationally representative sample (N = 13,905) of white, African American, Latino, Asian, and Native American adolescents between the ages of 12 and 19 participating in the National Longitudinal Study of Adolescent Health.Findings:Prevalence rates of certain chronic illnesses (obesity, asthma, and high cholesterol) among Latino adolescents exceed rates for the same illnesses among white adolescents. Comparisons between rural and non‐rural youth reveal a rurality disadvantage in terms of any chronic illness likelihood among Latino, Asian, and Native American youth not evident among whites or African Americans. Among Latino youth (N = 2,505), Mexican Americans show lower health risk for any chronic illness compared to other Latino groups. However, third generation Latinos and those who primarily speak English at home experience higher risk for any chronic illness than do those of first or second generation status, with amplification of the risk linked to English use at home among Latino youth living in rural areas.
CURRENT STATUS AND CONSERVATION NEEDS OF DUGONGS IN SOUTHERN JAPAN
Authors: Shirakihara Miki , Yoshida Hideyoshi , Yokochi Hiroyuki , Ogawa Hisao , Hosokawa Taro , Higashi Naoto , Kasuya Toshio
Published: June 2007

Abstract

We conducted aerial surveys of dugongs (Dugong dugon) using the line‐transect method and snorkeling surveys of dugong feeding trails in 1998 and 1999 around Okinawa Island (26°30′N, 128°00′E) and the Sakishima Islands, southern Japan. A total of ten dugongs were sighted and feeding trails were confirmed in the sea grass beds off the east coast of Okinawa Island. In the Sakishima Islands, however, no dugongs were observed, and there was no evidence of feeding trails despite the existence of apparently suitable sea grass beds for feeding. The results of these surveys and other available information suggest that Okinawan dugongs represent a small, geographically isolated population. Our sightings of dugongs during the daytime, offshore of sea grass beds where feeding trails were recorded, suggest that Okinawan dugongs principally feed at night when human activities are limited. Survival of this remnant dugong population is threatened by habitat degradation and occasional entanglement mortality in fishing nets.
New Progress on Certified Reference Materials for Platinum‐Group Elements: IGGE GPt‐8, GPt‐9 and GPt‐10
Authors: Gu Tiexin , Shi Changyi , Pu Wei , Yan Weidong , Liu Mei , Yan Mingcai
Published: June 2007

Three new certified reference materials (CRM), certified for the platinum‐group elements (PGE), GPt‐8, GPt‐9 and GPt‐10 were developed based on the previous CRMs IGGE GPt‐1 to GPt‐7. The PGE concentration of GPt‐8 is about 1 ng g‐1. GPt‐9 and GPt‐10 are ore samples with PGE concentrations of more than 1 μg g‐1. A multi‐laboratory collaborative analysis scheme was adopted in the certification procedure, in which nine highly‐experienced institutes and laboratories participated. The samples were analysed for the six platinum‐group elements by nickel sulfide mini fire assay, with Te coprecipitation, and were determined by ICP‐MS. Osmium was determined by isotope dilution.
Rare Earth and Other Trace Element Content of NRCC HISS‐1 Sandy Marine Sediment Reference Material
Authors: Waheed Shahida , Rahman Asma , Siddique Naila , Ahmad Shujaat
Published: June 2007

The National Research Council (NRC), Ottawa, Canada sandy marine sediment reference material HISS‐1 was characterised for thirty‐seven trace elements by neutron activation optimised irradiation, cooling and counting protocols using the low power Miniature Neutron Source Reactor (MNSR) as a neutron source. This INAA methodology quantified twenty additional elements including ten rare earth (Ce, Dy, Eu, Ho, La, Lu, Nd, Sm, Tb and Yb) and ten other elements (Ba, Br, Cs, Ga, Hf, Rb, Sc, Ta, Th and Zr) missing in the final NRCC certification. A large number of values produced by different irradiation schemes together with the use of certified reference materials in the quantification step that showed good precision, provided confidence in the results. The reliability of the REE data was checked by plotting chondrite‐normalised graphs.
Learning styles of first-year medical students attending Erciyes University in Kayseri, Turkey
Authors: Baykan Zeynep , Naçar Melis
Published: June 2007

Educational researchers postulate that every individual has a different learning style. The aim of this descriptive study was to determine the learning styles of first-year medical students using the Turkish version of the visual, auditory, read-write, kinesthetic (VARK) questionnaire. This study was performed at the Department of Medical Education of Erciyes University in February 2006. The Turkish version of the VARK questionnaire was administered to first-year medical students to determine their preferred mode of learning. According to the VARK questionnaire, students were divided into five groups (visual learners, read-write learners, auditory learners, kinesthetic learners, and multimodal learners). The unimodality preference was 36.1% and multimodality was 63.9%. Among the students who participated in the study (155 students), 23.3% were kinesthetic, 7.7% were auditory, 3.2% were visual, and 1.9% were read-write learners. Some students preferred multiple modes: bimodal (30.3%), trimodal (20.7%), and quadmodal (12.9%). The learning styles did not differ between male and female students, and no statistically significant difference was determined between the first-semester grade average points and learning styles. Knowing that our students have different preferred learning modes will help the medical instructors in our faculty develop appropriate learning approaches and explore opportunities so that they will be able to make the educational experience more productive.
A tribute to Italian physiologists of Jewish descent evicted during the persecution ordered by the Fascist Regime in 1938
Authors: Troiani Diana , Manni Ermanno
Published: June 2007

The present report commemorates the persecution of five renown Italian physiologists of Jewish descent that lost their chairs in medical schools because of the anti-semitic policies of the fascist regime. In 1938, Mussolini promulgated the Racial Laws, officially with the aim of safeguarding the purity of the Italian race in conquered African colonies. However, their true intent was to persecute the Italian Jewish community in agreement with the policy of Nazi Germany. In accordance with the Racial Laws, all non-Aryans were banished from professional activities and were evicted from public, social, and academic life. As a result, 98 full professors in Italian universities were removed from their academic positions. In medical schools, physiology, more than other discipline, lost the most prominent faculty members. Of the 17 full Professors of Human Physiology, five were of Jewish descent, and all were evicted: they were Camillo Artom from Palermo, Mario Camis from Bologna, Carlo Foà from Milan, Amedeo Herlitzka from Turin, and Ugo Lombroso from Genoa. All were talented and famous scientists who were forced to leave Italy and take refuge in foreign countries. At the end of World War II, Camis, Foà, Herlitzka, and Lombroso returned to Italy and resumed their previous academic positions, whereas Artom remained in the United States. Unfortunately, Camis died later that year. During the postwar period, some of the fascists responsible for the Jewish persecution were killed or committed suicide while the survivors were imprisoned and prosecuted. However, all were soon released and resumed their former positions.
A classic learning opportunity from Arthur Guyton and colleagues (1955): circuit analysis of venous return
Authors: Curran-Everett Douglas
Published: June 2007

The circuit analysis of an electric analog of the systemic circulation, the focus of a classic paper by Guyton, Lindsey, and Kaufmann, provides a framework for understanding the factors that impact venous return and for appreciating the value of modeling physiological systems. The classic 1955 paper by Guyton, Lindsey, and Kaufmann gives your students an opportunity to learn about modeling from the physiologist who pioneered it (Guyton) and demonstrates that mathematics and data graphics are fundamental tools with which to learn about the regulation of the cardiovascular system. In this essay, I outline avenues of discovery by which your students can explore the factors that impact venous return.
The ups and downs of peer review
Authors: Benos Dale J. , Bashari Edlira , Chaves Jose M. , Gaggar Amit , Kapoor Niren , LaFrance Martin , Mans Robert , Mayhew David , McGowan Sara , Polter Abigail , Qadri Yawar , Sarfare Shanta , Schultz Kevin , Splittgerber Ryan , Stephenson Jason , Tower Cristy , Walton R. Grace , Zotov Alexander
Published: June 2007

This article traces the history of peer review of scientific publications, plotting the development of the process from its inception to its present-day application. We discuss the merits of peer review and its weaknesses, both perceived and real, as well as the practicalities of several major proposed changes to the system. It is our hope that readers will gain a better appreciation of the complexities of the process and, when serving as reviewers themselves, will do so in a manner that will enhance the utility of the exercise. We also propose the development of an international on-line training program for accreditation of potential referees.
Trends in the Design and Performance of Tantalum Capacitors
Authors: Harris L. F.
Published: June 2007

This paper shows the type of development that has occurred over recent years in tantalum capacitors, with
particular reference to the sintered tantalum powder – liquid electrolyte (wet Ta) system. In the ‘wet’ system, the
various defects that arise, such as silver migration, scintillation and field crystallisation, are illustrated and the effect
of improvement in initial particle shapes on final surface area is considered.
Aspects of Threshold Switching
Authors: Smith W. , Shaw R. F. , Henisch H. K.
Published: June 2007

It is shown that the delay time of a chalcogenide glass threshold switch is not significantly affected by strong
illumination, sufficient to increase the conductance by an order of magnitude. This means that the initiation of
threshold switching is not due to free carriers within the bulk material. Noise measurements in the pre‐threshold
region demonstrate the existence of noise, in excess of thermal noise, increasing sharply towards the threshold
point. The results suggest impact ionization by carriers originating at the electrodes as the best available hypothesis
for the nature of the threshold condition.
The Use of Niobium as an Anode Material in Liquid Filled Electrolytic Capacitors
Authors: Jackson N. F. , Hendy J. C.
Published: June 2007

Field crystallisation during the anodisation of niobium can be reduced to a minimum by employing a phosphoric
acid electrolyte at low temperature. For certain other electrolyte systems, reduced crystalline growth rates are
obtained by increasing the solute concentration or by adding either phosphate or ethylene glycol.

Porous anodes were prepared from niobium powders of nominal particle size 8μm or 10μm using sintering
temperatures of 1400–1800℃. The capacitance of these bodies was in the range 4,600–10,000μF Vgm-1. after
anodising at 20℃. Shelf tests on experimental capacitors filled with a concentrated sulphuric acid electrolyte
indicated a maximum working temperature of 85℃. Although chemical compatibility between the dielectric oxide
and the sulphuric acid was maintained up to 125℃, thermal effects on the oxide at this temperature resulted in
unacceptably large increases in capacitance and leakage current. Endurance tests at 85℃ of capacitors rated at
35V/200μF or 63V/60μF showed good stability of capacitance and dissipation factor over a period of 3000 hours.
Final leakage currents were in the region of 10-4μAμF-1V-1
at 85℃ and crystalline growth was greatly restricted.
Electrical Contacts to Evaporated Cadmium Selenide
Authors: de Mey G.
Published: June 2007

The voltage‐current characteristics of evaporated gold‐CdSe contacts have been experimentally investigated. In
contrast to the experiments of Weimer with Cadmium Sulphide, it was found that CdSe makes no ohmic contact
with the underlying gold layers. The reverse biased contact has a zener‐like behaviour. With silver ink contacts
deposited upon the CdSe, perfectly ohmic contacts were obtained.
Direct Chip Mounting — A Challenge to the Design Engineer
Authors: Lorman J. , Prochaska J.
Published: June 2007

The extrapolation of development trends in the area of technologically complicated electronic equipment shows an ever increasing complexity in semiconductor technology. This development has so concerned the constructors of electronic equipment that progress in the technology of mounting and interconnection has taken a secondary place.

This growing divergence between a fast developing microelectronic industry, and a conservative state of the macroelectronics industry, is a driving force with regard to the progress to effective connection technologies at every level of mounting. The technological solution to all systems will then become more coordinated.

The mounting of components to printed circuit boards is traditionally a soldering operation. This principle lead to the development of full automation, and is a standard mounting technology. The growth of integration at the chip level has however brought new requirements that are only satisfied with difficulty.

Newly developed requirements show that the use of dual‐in‐line packages will be unsatisfactory. New methods must be designed to connect the chips directly to the printed circuit board, going from the chip as the smallest mounted unit.

Requirements for very complex electronic equipment with a high degree of integration (LSI or VLSI) are not satisfied using traditional mounting systems. These require a totally new mounting concept, from the chips to the printed circuit board.

In this paper alternatives to printed circuit board technology with insulated wiring (multilayers), and the mounting of chips from film carriers, are evaluated. These principles have a good possibility of further improvement as progress in mounting technology continues.

Price reductions cause an extension of application possibilities and an extension of electronic designs. It is harder to make choices for new designs when there are more degrees of freedom. However the function of chips as the basic element is unchangeable and optimum designs need to be based on this concept.
Ceramic on Metal Substrates Produced by Plasma Spraying for Thick Film Technology
Authors: Gołonka Leszek , Pawłowski Lech
Published: June 2007

The arc plasma spraying process was applied to obtain ceramic coatings on stainless steel substrates. The outer coatings were formed from pure alumina or alumina + 2 wt. % titania mixture. The nichrome intermediate coating was applied to increase adhesion of ceramic coating to stainless steel. The X‐ray analysis, metallographic and SEM investigations of the sprayed coatings were also carried out. The effect of interaction of thick film conductor and resistor compositions was studied. Conductor ink P 202 PdAg and resistor ink DP 1321 were evaluated. The TCR, resistance stability were measured as a function of firing cycles. These parameters and the resistivity of sprayed alumina were compared with standard 96% alumina substrate characteristics.
Versatile Packaging Concept Using Thick Film Hybrids for Analog and Digital Circuits
Authors: Zimmer Ch.
Published: June 2007

The design parameters of a packaging concept are described, which allows the realization of a complex electronic module in a closed casing using commercially available components. These are soldered to multilayer thick‐film circuits, mounted on metallic heat sinks. The multi‐layer structure contains silver bearing conductors and supports trimmable resistors. The information presented concerns mainly the fabrication of the thick‐film circuits and the thermal design.
Comparative Study of Thick Film Dielectrics
Authors: Vermeirsch Walter
Published: June 2007

SEM–observation and analysis provide a quick and reliable method of predicting the cross‐over and multilayer characteristics of a dielectric paste. Surface and bulk porosity, flow behaviour and chemical composition, determined by SEM are closely related to the results of electrical and environmental tests. From the latter, voltage breakdown and humidity tests should be selected as most suitable for the comparison of various systems.
Design of a 108 Pin VLSI Package With Low Thermal Resistance
Authors: Otsuka Kanji , Usami Tamotsu
Published: June 2007

The design of a 108 pin VLSI package is described. The package has low thermal resistance and can, therefore, dissipate 4 watts of power. The package design is now being used commercially in high‐end computers made by Hitachi.
Description and Performance of a Novel Concept “Single Level” Ceramic Chip Carrier
Authors: de Keyser Andre , Delautre Claude , Nameche Guy
Published: June 2007

Two different designs of ceramic chip carriers are discussed. A carrier capable of being hermetically sealed has been developed which uses a glass seal combined with an epoxy bonded chip. A second carrier which does not have hermeticity has also been designed in which the alumina cap is attached to the base with a thermo setting resin. The applicability of these two types is examined.
New Thick‐Film Temperature Sensors Applied in Some Hybrid Measurement Devices
Authors: Gondek Janusz J. , Wójcicki Marek A.
Published: June 2007

The present paper is devoted to the technological problems connected with the construction, the choice of pastes and substrates, the screening process and the laser or abrasive trimming involved in the production of thick‐film resistance temperature sensors designed by the authors. It also gives their main functional parameters and characteristics indicating the possility of the use of thick‐film sensors not only in the measurement of temperatures, in a wide range, but also in determining the velocity and volume of flowing gases or liquids. On the basis of the relations investigated, the authors give examples of constructions of a few hybrid measurement devices for use in industry, transportation
and medicine. Technical and economic aspects of the production of hybrid measurement devices
are also dealt with.
The Oxide‐Forming Role of Water in Aluminum Electrolytic Capacitors
Authors: Bernard Walter J. , Florio Steven M.
Published: June 2007

The effect of the water content of several electrolytic solutions on their ability to form dielectric oxide films on aluminum was examined. Anhydrous electrolytes were found to be incapable of forming such films, but the addition of small amounts of water made it possible for these solutions to perform as normal oxide‐film formers. The anodizing behavior of an anhydrous electrolyte composed of methyl cellosolve and ammonium picrate was investigated in detail in both experimental aluminum anodizations and in finished capacitors, in an attempt to correlate the behavior of the electrolyte as an anodizer of bare foil with the aging and life test characteristics of capacitors containing that electrolyte. The results tend to support the conclusion that water is essential to the proper performance of electrolytic capacitors.
Card‐Edge Connector Reliability
Authors: Villien Poul
Published: June 2007

This paper considers the results of using tin or T/A platings as a substitute for gold in card‐edge connectors.

Measurements have been made on mated systems before and after various environmental tests. It has been shown that gold‐gold contacts still provide the best reliability even if some of the gold platings have become worn through due to constant withdrawal and insertion.
Compliant Press‐Fit Technology Integrated Into a New Back Panel Packaging Approach
Authors: Kerkhoff A.
Published: June 2007

Involving, as it does, DIN and Reversed DIN board connectors, compliant press‐fit pins, round cable, flat cable, and coaxial‐connectors, the Berg Backpanel System has, over the past two years, gained a recognized position in the European and US markets.

Development and expansion of the system in depth, and in breadth, is still ongoing. One of the major subjects is press‐fit: preloaded press‐fit connectors and studies focused on the relationship between printed circuit board properties vs. compliant press‐fit pin design.

This paper presents results of these developments and discusses design options.
Improvements in Multilayer Ceramic Capacitors
Authors: Dyson A. F.
Published: June 2007

The increased use of Multilayer Ceramic Capacitors in both chip and encapsulated formats is mainly due to their excellence at decoupling Integrated Circuit Random Access Memories.

As a result of this excellent performance, large volumes of this type of capacitor are currently used and indications are that further increases in volume will continue over the next decade. There is therefore a market requirement for continued improvements in performance, reliability and cost.

There have been major processing changes for cost reduction reasons, which have resulted in new dielectric systems, changes in electrode types and greatly reduced dielectric thicknesses.

Studies of the failure mechanisms in these capacitors have been made, and this paper outlines the effect of process and materials on the reliability of these capacitors.

In addition, critical process stages are highlighted and control levels indicated. Some new work on testing techniques and its relevance to delaminations is also reported.
Some Useful Design Parameters of Non‐Uniform Integrated Band‐Pass Filters
Authors: Singh H. R.
Published: June 2007

Important design parameters for a two‐port three‐terminal band‐pass filter configuration of the integrated thin‐film exponential distributed parameter R–C–KR microstructure are presented. The circuit exhibits load independent characteristics. The changes in the value of design parameters under varying loading conditions are given. Various plots illustrating the inter‐relationship of the different parameters with each other that can serve as guidelines for a system designer to obtain a pre‐assigned pattern of the performance characteristics of the microstructure are included.
New Alumina Substrates for Microelectronics
Authors: Niwa K. , Murakawa K.
Published: June 2007

Alumina substrates of Al2O3–MgO–Cr2O3 give excellent surface smoothness. These were studied with respect to
their green tapes, the surface finish of fired substrates, and in particular smoothness. The factors contributing to
these characteristics were investigated, in particular the effect of the addition of Cr2O3 on surface smoothness.
A Review of Solder Glasses
Authors: Frieser R. G.
Published: June 2007

A compilation of data on solder glasses from the literature is presented. Sources are: Chemical Abstracts, Ceramic Abstracts, Abstracts in Physics and Chemistry of Glasses, and pertinent books. Even though not exhaustive, domestic and foreign sources are included.
The Tunnel Etching of Aluminium
Authors: Jackson N. F.
Published: June 2007

The electrochemical potential for the active dissolution of aluminium in sodium chloride solution is found to be
linearly related to the logarithm of the chloride ion concentration. The value of E0 calculated on the basis of the
postulated electrode reaction is approximately 0.3 V more negative than the experimental value and a similar
inequality is observed for bromide and iodide electrolytes.

The electrochemical etching of aluminium in chloride, bromide or iodide solutions is initiated at weak points in
the surface oxide film. Subsequent stages in the dissolution process involve a random attack leading to the
formation of cavities and a selective attack leading to tunnelling. The dominance of one or other of these
dissolution modes is largely dependent upon the electrochemical parameters. It is suggested that the reason for this
dependency is associated with an alteration in the electrode potential for dissolution resulting from changes in the
halide ion concentration within the tunnel structure.
The Equivalent Series Resistance in Electrolytic Capacitors
Authors: Hayatee F. G.
Published: June 2007

The analysis of electrolytic capacitors as a distributed network is examined. The parameters contributing to the
equivalent series resistance (E.S.R.) have been determined for various production capacitors at low and high frequencies.
Electrical Behaviour of Langmuir Films: A Review, Part II
Authors: Agarwal V. K.
Published: June 2007

The electrical behaviour of thin films obtained by a variety of processes, e.g. thermal evaporation in
vacuum, has been extensively studied. The study of organic mono‐ and multilayer films obtained by
the Blodgett–Langmuir technique (commonly referred to as Langmuir films), however, has gained
considerable momentum only during the past decades. Unlike evaporated films, the stiking features
of these organic films are their controllable thicknesses down to one monolayer (~25 Å) and the
possibility of obtaining them free from holes and conducting imperfections. The aim of this paper is
to describe the film deposition techniques, some of the properties of the films so obtained and to
review their electrical behaviour. It is also intended to make this review a comprehensive and
up‐to‐date source of information for those who are either already engaged in this field or are
planning to adopt Langmuir films for future investigations.

In this survey, emphasis is put on the possible problems worth further study to get more insight
into the basic properties of these films. Further, since the latter possess some interesting electrical
properties, this paper may prove useful in the assessment of our depth of knowledge about them and
in reducing the existing gap between basic research and technological applications. Their potential
usefulness in developing devices is therefore also discussed.

The survey has been divided into two parts. Part I was concerned with deposition techniques,
the physical properties of Langmuir films and certain electrical properties, namely dielectric
behaviour and electrical conduction phenomena. This second part is concerned with electrical
breakdown behaviour, voltage induced changes in electrical behaviour (forming) and ionic transport
phenomena in the films and finishes, with suggestions as to future trends in work with such films
together with a summary of possible applications.

To assist the reader, the two parts have been numbered consecutively with regard to sections of
the text, figures and references. “Appropriate” references already cited in Part I are given again at the
end of this part.
Extremely High Frequency Resolution and Low Harmonic Distortion DigitalLook‐Up‐Table Sinusoidal Oscillators
Authors: Al-Ibrahim (Jarrah) M. M.
Published: June 2007

New techniques to efficiently increase the frequency resolution of digital sinusoidal
oscillators based on look‐up‐table (LUT) methods are proposed. The increase in frequency
resolution is achieved while maintaining very low level of spurious harmonic
distortion. The proposed techniques increase the LUT length to a level at which the
spurious harmonic distortion is negligible. The first proposed technique is based on
partitioning the address register into three sets and dividing the available LUT length
into three smaller tables addressed according to the content of the address register sets.
The second proposed technique utilizes one LUT and interpolates the values of the
samples that are not stored in the table. The third proposed technique is similar to the
first technique with the advantage of simpler implementation and lower levels of
spurious harmonic distortion. The proposed techniques are simulated and their performance
is compared with that of the direct LUT and trigonometric interpolation
methods. The simulation results show that the proposed techniques are superior to both
direct LUT and trigonometric interpolation methods.
New Solution Method of Time‐dependent Schrödinger Equation Using ImprovedBoundary Conditions
Authors: Song C. P. , Lee M. R. , Yarn K. F.
Published: June 2007

Numerical solution of the time‐dependent Schrödinger equation for open system structures has been impeded by the difficulty in handing open‐system boundary conditions.
This paper presents a new numerical method for time‐dependent Schrödinger equation
and a boundary condition method to simulate the interaction with ideal particle reservoirs
at the structure boundaries.
Active Components Based on Dynamic Negatrons
Authors: Molchanov Pavlo , Mishra Arun K. , Linnik Helen , Mulyar Pavlo
Published: June 2007

The active elements based on dynamic transistor negatrons (circuits with negative active
differential resistance) are introduced. The principles of dynamic transistor negatrons
simulation has been developed on the basis of non‐linear charge model. Parameters,
which characterize non‐linear mode of dynamic transistor negatrons, are derived. Nonlinear
equivalent circuit and Volterra series are used to calculate parameters of negatrons.
Particular attention is devoted to the frequency mixers and frequency switches. An experimental
frequency mixer has been described, that has confirms the theoretical predictions.