bluuebunny/crossref_metadata_2025 huggingface dataset:
Research and Application of Evaluation Methods for Functional Characteristics of Oil-Based Drilling Fluid in Shale Gas Wells
Authors: Gao Dewei , Xie Jiajun , Huang Shengming , Wu Shenyao , Wu Pengcheng , Huang Weian
Published: March 2021

Intelligent unconventional reservoir optimal production control technology is a comprehensive technology, involving geology, reservoir simulation, and efficient drilling and completion. Efficient drilling and completion provides a flow channel for unconventional oil and gas exploitation and a wellbore with good integrity for reservoir transformation, which is an important link in the efficient development of unconventional oil and gas. The application of industry standard method to evaluate the performance of oil-based drilling fluid has the problem of poor correlation. It cannot reflect the difference of performance among oil-based drilling fluid systems, which lacks the significance for field construction. Based on shale expansion, rolling dispersion experiment, and microporous membrane filtration loss test, the physicochemical mechanism of borehole wall instability in shale formation was investigated. The evaluation methods of shale lubrication, antiaccretion test, slake durability, buck hardness test, etc. are put forward, and the formula of oil-based drilling fluid is optimized. The lubrication and antiaccretion experiment method can effectively and intuitively characterize the cleaning and lubrication effect of drilling fluid on drilling tools. The slake durability evaluation method simulates the collision between drill cuttings and the drill string and well wall. The bucking hardness experiment is through testing the cuttings and the hardness change after drilling fluid action reflects its inhibitory effect. The new methods were used to evaluate the oil-based drilling fluid used in 4 wells in the Changning block. It was found that the drilling fluid of CN209H2 well adhered to the steel column with at least 0.41 g of cuttings; the recovery rate of the drilling fluid resistance of CN209H1 was up to 87.70%, and YX1200 oil-based drilling fluid plugging agent was selected through the microporous membrane experiment. In the process of drilling the well CN209H5, the new oil-based drilling fluid formulation improved the lubrication performance by 44%, accompanied by 95.48% recovery rate and less than 10 mL HTHP fluid loss at the same time. The research results show that the oil-based drilling fluid system optimized according to the new method can significantly inhibit shale hydration and dispersion and can effectively solve the problem of unstable performance of traditional oil-based drilling fluids in the Changning block.
Type 2 Diabetes and Cancer: An Umbrella Review of Observational and Mendelian Randomization Studies
Authors: Pearson-Stuttard Jonathan , Papadimitriou Nikos , Markozannes Georgios , Cividini Sofia , Kakourou Artemisia , Gill Dipender , Rizos Evangelos C. , Monori Grace , Ward Heather A. , Kyrgiou Maria , Gunter Marc J. , Tsilidis Konstantinos K.
Published: March 2021

Background:

Type 2 diabetes mellitus (T2DM) has been associated with an increased risk of developing several common cancers, but it is unclear whether this association is causal. We aimed to summarize the evidence on T2DM and cancer and evaluate the validity of associations from both observational and Mendelian randomization (MR) studies.

Methods:

We performed an umbrella review of the evidence across meta-analyses of observational studies that examined associations of T2DM with risk of developing or dying from site-specific cancers, and MR studies that explored the potential causal association of T2DM and associated biomarkers with cancer risk.

Results:

We identified eligible observational meta-analyses that assessed associations between T2DM and cancer incidence for 18 cancer sites, cancer mortality for seven sites, and cancer incidence or mortality for four sites. Positive associations between T2DM and six cancers reached strong or highly suggestive evidence. We found eight MR studies assessing the association of genetically predicted T2DM and seven and eight studies assessing the association of genetically predicted fasting insulin or fasting glucose concentrations, respectively, upon site-specific cancers. Positive associations were found between genetically predicted T2DM and fasting insulin and risk of six cancers. There was no association between genetically predicted fasting plasma glucose and cancer except for squamous cell lung carcinoma.

Conclusions:

We found robust observational evidence for the association between T2DM and colorectal, hepatocellular, gallbladder, breast, endometrial, and pancreatic cancers.

Impact:

Potential causal associations were identified for genetically predicted T2DM and fasting insulin concentrations and risk of endometrial, pancreas, kidney, breast, lung, and cervical cancers.
Concentrations of Cotinine and 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol (NNAL) in U.S. Non-Daily Cigarette Smokers
Authors: Gutiérrez-Torres Daniela S. , Wang Lanqing , Blount Benjamin C. , Xia Baoyun , Sosnoff Connie S. , Shiels Meredith S. , Inoue-Choi Maki , Etemadi Arash , Freedman Neal D.
Published: March 2021

Background:

Accumulating evidence suggests that non-daily smokers have higher disease and mortality risks than never smokers. Yet, the accuracy of self-reported non-daily cigarette smoking is poorly understood.

Methods:

We examined the concordance between self-reported non-daily smoking and serum cotinine in 18,835 adult participants (20 years or older) of the 2007 to 2014 National Health and Nutrition Examination Surveys, in comparison with daily smokers and nonsmokers. We also analyzed concentrations of the urinary biomarker 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) by smoking status.

Results:

In the study sample, 77.8% (14,660) reported currently not smoking (nonsmokers), 18.3% (3,446) smoked every day (daily smokers), and 3.9% (729) smoked on some days of the past month (non-daily smokers). Just 2.1% of nonsmokers had cotinine concentrations in the active smoking range (>10 ng/mL), compared with 70.4% of non-daily and 98.8% of daily smokers. Non-daily smokers reported smoking a median of 24 cigarettes per month [interquartile range (IQR) = 9–60] and had substantially higher concentrations of NNAL (median = 72.5; IQR = 14.8–211.0 pg/mL) than nonsmokers (median = 0.4; IQR = 0.4–2.1 pg/mL), although lower than daily smokers (median = 294.0; IQR = 148.0–542.0 pg/mL). Among non-daily smokers, concentrations of cotinine and NNAL were positively correlated with days and cigarettes smoked per month (P < 0.001).

Conclusions:

We observed excellent concordance between self-reported non-daily cigarette smoking and concentrations of serum cotinine.

Impact:

These results provide evidence for the validity of self-reported non-daily smoking and indicate that non-daily smokers are exposed to substantial concentrations of carcinogenic nitrosamines regardless of the low number of cigarettes they smoke per month.
Circulating Protein Biomarkers for Use in Pancreatic Ductal Adenocarcinoma Identification
Authors: Lindgaard Sidsel C. , Sztupinszki Zsófia , Maag Emil , Chen Inna M. , Johansen Astrid Z. , Jensen Benny V. , Bojesen Stig E. , Nielsen Dorte L. , Hansen Carsten P. , Hasselby Jane P. , Nielsen Kaspar R. , Szallasi Zoltan , Johansen Julia S.
Published: March 2021

Purpose:

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. Most patients are diagnosed at an advanced stage where curative surgery is not an option. The aim of this study was to identify a panel of circulating proteins that could distinguish patients with PDAC from non-PDAC individuals.

Experimental Design:

We investigated 92 proteins known to be involved in inflammation, development, and progression of PDAC using the Olink immuno-oncology panel in serum samples from 701 patients with PDAC (stage I–IV), 102 patients with nonmalignant pancreatic diseases, and 180 healthy blood donors. Patients were included prospectively between 2008 and 2018. Plasma carbohydrate antigen 19-9 (CA19-9) was measured in all samples. The protein panels with the best diagnostic performances were developed by two bioinformaticians working independently, using LASSO and Ridge regression models.

Results:

Two panels of proteins (index I, containing 9 proteins + CA19-9, and index II, containing 23 proteins + CA19-9) were identified. Index I was able to discriminate patients with PDAC from all patients with non-PDAC, with a ROC AUC value of 0.92 [95% confidence interval (CI), 0.89–0.96] in the discovery cohort and 0.92 (95% CI, 0.87–0.97) in the replication cohort. For index II, the AUC value was 0.96 (95% CI, 0.95–0.98) in the discovery cohort and 0.93 (95% CI, 0.90–0.96) in the replication cohort. All nine serum proteins of index I were found in index II.

Conclusions:

This study identified two circulating protein indices with the potential to discriminate between individuals with and without PDAC.
Kwara-Central undergraduates’ perceived peer pressures on youths involvement in kidnapping
Authors: Shofiu Rasheed Adewuyi , Isiaka Abdulaziz
Published: March 2021

This study examined Kwara central undergraduates’ perceived peer pressure on youths’ involvement in kidnapping. This study was a descriptive survey. The population comprised of all undergraduates in Kwara Central Senatorial District. The target population was undergraduates from University of Ilorin and Alhikmah University, 500 students were randomly selected. A researcher design questionnaire was used for data collection while data collected were analyzed using frequency and percentage, mean, standard deviation (SD), ranking T-test and one-way analysis of variance. Research hypotheses were tested using independent T-test and also one-way analysis of variance at 0.05 level of significance. Findings revealed that peer pressure influences youth involvement in kidnapping in Nigeria; there was no significant difference in the influence of peer pressure on youth’s involvement in kidnapping as perceived by undergraduates based on academic level and school type. It was concluded that peer pressure influences youths’ involvement in kidnapping in Nigeria. We recommend both school and home adequate monitoring of students peers and friends at home and schools to prevent them from bad groups, adequate legislation to curb youth participation in kidnapping, good leadership examples for young ones to emulate and value reorientation of youths should be given top priority in educational curriculum.
Intercultural education in Kosovo: A longitudinal case study
Authors: White Cameron , Saqipi Blerim
Published: March 2021

This longitudinal qualitative study was conducted with Kosovo PhD students over a 3-year period who engaged in an ongoing intercultural education project at the University of Pristina’s Faculty of Education in Kosovo. The purpose of this article is to deepen the understanding of intercultural education with Kosovo as a critical case study. The data included pre-and post-open-ended surveys, one on one interviews, and follow up interviews regarding intercultural education during the longitudinal experiences. The findings of the study suggest the need to contextualize the issues of intercultural education and integrate local to global connections in relevant teaching, research, and service.
Evaluation of ICT tools accessibility to business education lecturers and students
Authors: Felicia Oluwalola Kikelomo
Published: March 2021

The paper evaluated the accessibility of Information and Communication Technology (ICT) tools to business education lecturers and students. Descriptive survey research design was adopted for the study. A total of 110 students and 20 lecturers were randomly selected from the department of business education for the study. Two research questions guided the study and one null hypothesis tested at 0.05 level of significance. The co-efficient of 0.86 was obtained for the research instrument. Research questions were reported as means and standard deviation values while T-test was used to test the null hypothesis. The results showed that ICT supportive tools were available for teaching and learning Business Education in Kwara State College of Education Ilorin. Hence, there was no difference in perception of lecturers and students accessibility of ICT tools. Respondents recommended provision of adequate ICT tools by the government for teaching and learning of business education. Trainings like seminars with workshop is of immense importance for ICT support staff.
From ivory tower to entrepreneurial university: Agenda for sustainable job creation among university graduates in Uganda
Authors: Oyugi Jacob
Published: March 2021

This paper stresses the importance of entrepreneurial university towards improving sustainable job creation and improvement in Uganda. The dilemmas the country is facing ranges from excessive poverty, graduate unemployment; over dependence on overseas items and technology; as well as low economic growth and development. These dilemmas are partly triggered by using improper education system especially at the university level. Many people argue that university education in Uganda is principally for its very own sake – to impart knowledge and a love of getting to know with greater paper qualifications. University training is for academic superiority disconnected from day-to-day realities, a closed environment in which information and intellect is the sanctuary of the self-selecting, privileged few – no grasp of what is vital for ordinary people. Yet the fact of university schooling is about helping humans grow in their lives by supporting them to live better life. This paper hence contends that change of universities in Uganda, from ivory tower to entrepreneurial universities, will prepare the students with the conduct, states of mind and attitudes with which to be self-reliant and contribute to job creation and advancement. The paper starts by highlighting the concept of university as an ivory tower. The objectives and framework for designing entrepreneurial university is presented next. The paper suggests that university programmes at all levels of instruction ought to be made significant to the community so as to supply the youth with the required entrepreneurial aptitude.
Developing instrument to measure the use of online comic as educational media
Authors: Radeswandri Radeswandri , Budiawan Afiq , Vebrianto Rian , Thahir Musa
Published: March 2021

Studies related to the development of instruments to measure the use of online comics as an educational media in tertiary institutions are still limited. A survey study was carried out on 60 students from various study programs at open university. The data collection was done using an online questionnaire. The data were analyzed using quantitative data analysis assisted by SPSS version 23.00 for Windows. The results of this study showed that: 1) the preparation and development of an evaluation instrument for the use of online comics for students was carried out using a theoretical development model to test seven research constructs; 2) the results of the construct validity and reliability testing indicated that the validity of the evaluation instrument for the use of online comics for students met the valid criteria because the value of r-count r-table (r-count 0.254); and 3) the reliability of the online comic use evaluation instrument for students that had been compiled and developed in this study also fulfilled the high category as indicated by the alpha Cronbach reliability coefficient of 0.980. This indicates that the instrument developed meets the requirements to be used in measuring the use of online comics for students.
The Interrelationship of Science Experiences, Beliefs, Attitudes, and Self-Efficacy: A Case Study of a Pre-Service Teacher with Positive Science Attitude and High Science Teaching Self-Efficacy
Authors: Kazempour Mahsa
Published: March 2021

This qualitative case study aimed to focus on the experiences and subsequent science and science teaching beliefs, attitudes, and self-efficacy of an elementary pre-service teacher, Heather, with extremely positive attitude and high self-efficacy. For this particular population of pre-service teachers, possessing a high science teaching self-efficacy alone is not sufficient to assume reform-based beliefs and teaching practices. This study was unique in that it concurrently explored the relationship between attitude, beliefs, and self-efficacy before and after the course. Initially, Heather’s attitude and self-efficacy with respect to science and science teaching were closely interrelated and a product of her own intrinsic interest in science and her unique K-12 experiences. Her beliefs appeared to have been shaped by both her actual science experiences and what she had witnessed in the classrooms. Heather’s course experiences shaped her post beliefs about science and science teaching, which consequently altered her attitude and confidence.
Coronary Collateral Flow Index Is Correlated With the Palmar Collateral Flow Index
Authors: Hollander Maurits R. , Jansen Matthijs F. , Schumacher Stefan P. , Stuijfzand Wijnand J. , van Leeuwen Maarten A.H. , van de Ven Peter M. , Horrevoets Anton J. , Nap Alex , Knaapen Paul , van Royen Niels
Published: March 2021

Objective:

The extent of the collateral circulation varies between individuals which affects morbidity and mortality. Experimental data show that collateral coherence between different organs is strain-dependent. Whether this interrelation is also present in humans is unknown. This study investigates the relation between the palmar and the coronary circulation in patients with coronary artery disease and which factors possibly influence collateral development.

Approach and Results:

In 50 patients with a chronic total occlusion, both the coronary collateral flow index (CFI) and the palmar CFI was measured. The correlation between both indices was determined, together with the relation to clinical variables. Mean coronary CFI was 0.51±0.16, and mean palmar CFI was 0.82±0.13. The coronary and palmar CFI were significantly correlated (ρ=0.48,
P
=0.001). Coronary CFI was 22% lower in low palmar CFI patients (<0.82) as compared with high palmar CFI patients (0.43±0.12 versus 0.57±0.18,
P
=0.03). In multivariable analysis, coronary CFI was significantly correlated with the palmar CFI and the duration of angina pectoris. Coronary CFI was inversely correlated with peripheral artery disease and systolic blood pressure.

Conclusions:

The coronary CFI and palmar CFI are significantly correlated, implicating collateral coherence between vascular beds in humans.
Impact of Reactive Oxidative Metabolites Among New Categories of Nonischemic Heart Failure
Authors: Nishihara Taiki , Yamamoto Eiichiro , Sueta Daisuke , Fujisue Koichiro , Usuku Hiroki , Oike Fumi , Takae Masafumi , Tabata Noriaki , Ito Miwa , Yamanaga Kenshi , Kanazawa Hisanori , Arima Yuichiro , Araki Satoshi , Takashio Seiji , Nakamura Taishi , Suzuki Satoru , Sakamoto Kenji , Izumiya Yasuhiro , Kaikita Koichi , Tsujita Kenichi
Published: March 2021

Background

We investigated the clinical significance of derivatives of reactive oxygen metabolites (DROMs), a new marker of reactive oxygen species, in patients with nonischemic heart failure (HF) and compared them among new categories of HF.

Methods and Results

We recruited 201 consecutively hospitalized patients with HF and measured DROM under stable conditions. Then, we divided them according to new categories of HF (HF with reduced ejection fraction [EF], HF with midrangeEF, and HF with preserved EF) without coronary artery disease. In subgroup analysis, we followed EF changes in patients with HF with reduced EF and classified them into HF with recovered EF or nonrecovered EF according to whether EF had improved to >40%. DROMs are significantly and independently associated with HF‐related events in patients with NIHF. There were no significant differences in DROM and the probability of HF‐related events among HF categories in Kaplan–Meier analysis. However, patients with HF with reduced EF and HF with preserved EF but not HF with midrange EF with HF‐related events had higher DROM than those without HF‐related events. In subgroup analysis, Kaplan–Meier analysis demonstrated that the probabilities of HF‐related events in HF with recovered EF were dramatically decreased. DROM were significantly higher in patients with HF with nonrecovered EF than in HF with recovered EF. In receiver operating characteristic analysis, the cutoff level of DROM for predicting improvements in HF with recovered EF was 347 Carratelli units. Furthermore, the C‐statistic value for predicting EF improvement for the DROM levels was 0.703. In multivariable logistic regression analysis, DROM was independently and significantly associated with the prediction of HF with recovered EF.

Conclusions

DROM measurements can provide important prognostic information for risk stratification in any category of NIHF.

Registration

URL:
https://www.umin.ac.jp/ctr/
; Unique identifier: UMIN000035827.
Tuberculosis and the Heart
Authors: López‐López José Patricio , Posada‐Martínez Edith L. , Saldarriaga Clara , Wyss Fernando , Ponte‐Negretti Carlos I. , Alexander Bryce , Miranda‐Arboleda Andrés Felipe , Martínez‐Sellés Manuel , Baranchuk Adrian ,   the Neglected Tropical Diseases, Other Infectious Diseases Affecting the Heart (the NET‐Heart Project)
Published: March 2021

Acquired tuberculosis continues to be a challenge worldwide. Although tuberculosis has been considered a global public health emergency, it remains poorly controlled in many countries. Despite being primarily a pulmonary disease, tuberculosis could involve the heart. This systematic review is part of the "Neglected Tropical Diseases and Other Infectious Diseases Involving the Heart" (the NET‐Heart Project) initiative from the Interamerican Society of Cardiology. This project aims to review the cardiovascular involvement of these heterogeneous diseases, advancing original algorithms to help healthcare providers diagnose and manage cardiovascular complications. In tuberculosis, pericardium involvement is relatively common, especially in AIDS, and tuberculosis is the most common cause of constrictive pericarditis in endemic countries. Myocarditis and aortitis by tuberculosis are rare. Clinical manifestations of cardiovascular involvement by tuberculosis differ from those typically found for bacteria or viruses. Prevailing systemic symptoms and the pericarditis diagnostic index should be taken into account. An echocardiogram is the first step for diagnosing cardiovascular involvement; however, several image modalities can be used, depending on the suspected site of infection. Adenosine deaminase levels, gamma interferon, or polymerase chain reaction testing could be used to confirm tuberculosis infection; each has a high diagnostic performance. Antituberculosis chemotherapy and corticosteroids are treatment mainstays that significantly reduce mortality, constriction, and hospitalizations, especially in patients with HIV. In conclusion, tuberculosis cardiac involvement is frequent and could lead to heart failure, constrictive pericarditis, or death. Early detection of complications should be a cornerstone of overall management.
Description of a new toad of Megophrys Kuhl & Van Hasselt, 1822 (Amphibia: Anura: Megophryidae) from western Yunnan Province, China
Authors: SHI SHENGCHAO , LI DONGHUI , ZHU WENBO , JIANG WEN , JIANG JIANPING , WANG BIN
Published: March 2021

A new species of genus Megophrys from Gaoligong Mountains, Yunnan Province, China is described. Phylogenetic analyses based on mitochondrial DNA and nuclear DNA all clustered the new species as an independent clade nested into the subgenus Panophrys. The smallest genetic distance based on 16S rRNA gene between the new species and its congeners was 3.0%. The new species could be identified from its congeners by a combination of following characters: moderate body size (SVL 31.0–34.8 mm in males); vomerine ridge weak, vomerine teeth absent; dorsal skin relatively smooth; tongue slightly notched behind; tympanum rounded and relatively large, 0.54 times of eye length; a horn-like tubercle on edge of each upper eyelid small; tibio-tarsal articulation reaches middle eye when leg stretched forward; finger tips rounded, not expanded to small pad; toes with narrow fringes and rudimentary webbing; ventral hindlimbs semitransparent purplish with greyish white pigments; ventral body scattered with distinct dark patches in the middle.
Quantitative Detection of Parathyroid Hormone Using Europium Complex Doped Silica Nanoparticles
Authors: Kim Hyun Tae , Go Anna , Lee Min-Ho
Published: March 2021

Parathyroid hormone (PTH) is a hormone that plays a critical role in bone remodeling because it regulates the calcium levels. Either higher or lower than normal range of PTH release can cause serious metabolic disorders such as hyperparathyroidism or hypoparathyroidism. Therefore, the
demand of highly sensitive monitoring sensor of PTH is on the rise. However, due to its presence of small size and low concentration in serum, the monitoring of a small change of PTH level is extremely difficult. In this article, we suggested the fabrication of europium complex doped nanoparticles
conjugated with PTH antibodies for the sensitive fluorescence monitoring of PTH. For the synthesis of europium complex, 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (NTA) and trioctylphosphine oxide (TOPO) are used to encapsulate europium. The amphiphilic polymer, polyvinylpyrrolidone (PVP),
was applied to hydrophobic europium complex, and then silica shell was synthesized on the complex. Using the europium complex doped silica nanoparticles, we could obtain approximately 4.24-fold enhanced fluorescence in low levels of PTH in PBS, when compared to the conventional enzyme-linked
immunosorbent assay (ELISA). In addition, we could obtain the sensitive PTH immunoassay in PTH spiked serum with high selectivity.
Chitosan Oligosaccharide Lactate-Coated Ultrasmall Gadolinium Oxide Nanoparticles: Synthesis, In Vitro Cytotoxicity, and Relaxometric Properties
Authors: Ahmad Mohammad Yaseen , Ahmad Md. Wasi , Yue Huan , Ho Son Long , Cha Hyunsil , Marasini Shanti , Tegafaw Tirusew , Liu Shuwen , Ghazanfari Adibehalsadat , Chae Kwon-Seok , Chang Yongmin , Lee Gang Ho
Published: March 2021

In this study, hydrophilic and biocompatible chitosan oligosaccharide lactate (COL)-coated ultra-small gadolinium oxide nanoparticles (NPs) were synthesized through a one-pot polyol method and characterized by various experimental techniques. The In Vitro cellular cytotoxicity
assay indicated that the COL-coated gadolinium oxide NPs were non-toxic up to 500 μM Gd. In addition, their water proton spin relaxivities (i.e., r1 and r2) were estimated to be 13.0 and 27.0 s−1mM−1, respectively,
which are higher than those of commercial magnetic resonance imaging (MRI) contrast agents. The application potential of the solution sample as a T1 MRI contrast agent was demonstrated In Vitro by measuring map images in which dose-dependent contrast enhancements were observed.
Organic Thin-Film Characteristics Modulated by Deposition Substrate Rotation Speed and the Effect on Organic Light-Emitting Diodes
Authors: Choi Geun Su , Baek Dong-Hyun , Park Young Wook
Published: March 2021

In this paper, we report on the effects of the substrate thermal evaporation process rotation speed on the electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs). In general OLED research, rotational and angle tilted deposition are widely used to maintain
uniformity. However, there have been few reports on the effects of this deposition method on film characteristics. We analyzed these effects and found that the film density and its refractive index showed remarkable changes as a function of substrate rotational speed during tilted deposition.
The EL characteristics of the transport layer of fluorescent OLEDs were also significantly affected. We derived the OLED optimal thickness and refractive index from our calculations.
Design of a Capacitorless Dynamic Random Access Memory Based on Ultra-Thin Polycrystalline Silicon Junctionless Field-Effect Transistor with Dual-Gate
Authors: Lee Sang Ho , Cho Min Su , Jung Jun Hyeok , Jang Won Douk , Mun Hye Jin , Jang Jaewon , Bae Jin-Hyuk , Kang In Man
Published: March 2021

In this paper, a 1T-DRAM based on the junctionless field-effect transistor (JLFET) with an ultrathin polycrystalline silicon layer was designed and investigated by using technology computer-aided design simulation (TCAD). The application of a negative voltage at the control gate results
in the generation of holes in the storage region by the band-to-band tunneling (BTBT) effect. Memory characteristics such as sensing margin and retention time are affected by the doping concentration of the storage region, bias condition of the program, and length of the intrinsic region.
In addition, the gate acts as a switch that controls the transfer characteristics while the control gate plays a role in retaining holes in the hold state. The device was optimized, considering various parameters such as the doping concentration of the storage region (Nstorage),
intrinsic region length (Lint), and operation bias conditions to obtain a high sensing margin of 49.7 μA/μm and a long retention time of 2 s even at a high temperature of 358 K. The obtained retention time is almost 30 times longer than that predicted
for modern DRAM cells by the International technology roadmap for semiconductors (ITRS).
Electrical Coupling for Monolithic 3-D Integrated Circuit Consisting of Feedback Field-Effect Transistors
Authors: Oh Jong Hyeok , Yu Yun Seop
Published: March 2021

In this study, for two cases of monolithic 3-dimensional integrated circuit (M3DIC) consisting of vertically stacked feedback field-effect transistors (FBFETs), the variation of electrical characteristics of the FBFET was presented in terms of electrical coupling by using technology
computer aided design (TCAD) simulation. In the Case 1, the M3DIC was composed with an N-type FBFET in an upper tier (tier2) and a P-type FBFET in a lower tier (tier1), and in the Case 2, it was composed with the FBFETs of opposite type of the Case 1 on each tier. To utilize
the FBFET as a logic device, the study on optimal structure of FBFET was first performed in terms of reducing a memory window. Based on the N-type FBFET, the memory window was investigated with different values of doping concentration and length of channel region divided into two regions.
The threshold voltage, capacitance, and transconductance of two cases of M3DIC composed with proposed FBFET were investigated for different thickness of an interlayer dielectric (TILD). In the Case 1, only for reverse sweep, the threshold voltage of FBFET in the tier2 was
changed significantly at TILD < 15 nm, and the capacitance and transconductance of FBFET in the tier2 changed significantly at TILD < 20 nm, as bottom gate voltage applied with 0 and 1 V. In the Case 2, the electrical characteristics of FBFET in the
tier2 changed greater than Case 1 with different TILD.
Characterization of Spatial Distribution of Trap Across the Substrate in Metal-Insulator-Semiconductor Structure with Band Bending Effect
Authors: Yu Jintae , Yoo Han Bin , Kim Hae Sung , Ryu Ji Hee , Choi Sung-Jin , Kim Dae Hwan , Kim Dong Myong
Published: March 2021

We report the technique of trap distribution extraction according to the vertical position of the substrate in the p-MOSFET. This study was conducted on a single device. This technique is an experimental method. Ctrap was extracted based on the deep depletion
C–V characteristics. In VFB, the trap level is neutral. When bias is applied, the energy band bends, resulting in modulation of the quasi-Fermi level. The area created by the bending of the energy band is equal to the area created by the Fermi level modulation.
The trap level existing in this area becomes charged. Considering this, the spatial distribution of Trap was extracted. The trap extracted by the proposed method has a maximum value at the interface, rapidly decreases, and is distributed up to 8 nm in the vertical direction. The study of trap
spatial distribution is expected to be applicable to the separation of trap interface state and bulk trap extraction later.
Design of a Capacitorless Dynamic Random Access Memory Based on Junctionless Dual-Gate Field-Effect Transistor with a Silicon-Germanium/Silicon Nanotube
Authors: Lee Sang Ho , Cho Min Su , Mun Hye Jin , Park Jin , An Hee Dae , Jang Jaewon , Bae Jin-Hyuk , Kang In Man
Published: March 2021

In this paper, a 1T-DRAM based on the junctionless field-effect transistor (JLFET) with a silicon-germanium (SiGe) and silicon (Si) nanotube structure was designed and investigated by using technology computer-aided design (TCAD) simulations. Utilizing bandgap engineering to make a
quantum well in the core–shell structure, the storage pocket is formed by the difference in bandgap energy between SiGe and Si. By applying different voltage conditions at the inner gate and outer gate, excess holes are generated in the storage region by the band-to-band tunneling (BTBT)
mechanism. The BTBT mechanism results in the floating body effect, which is the principle of 1T-DRAM. The varying amount of the accumulated holes in the SiGe region allows differentiating between state “1” and state “0.” Additionally, the outer gate plays a role of
the conventional gate, while the inner gate retains holes in the hold state by applying voltage. Consequently, the optimized SiGe/Si JLFET-based nanotube 1T-DRAM achieved a high sensing margin of 15.4 μA/μm, and a high retention time of 105 ms at a high temperature of 358
K. In addition, it has been verified that a single cycle of 1T-DRAM operations consumes only 33.6 fJ of energy, which is smaller than for previously proposed 1T-DRAMs.
The Effect of Grain Boundary on Electrical Characteristics in the Source and Drain Regions of Polycrystalline Silicon Based in One Transistor Dynamic Random Access Memory
Authors: An Hee Dae , Cho Min Su , Mun Hye Jin , Lee Sang Ho , Park Jin , Jang Jaewon , Bae Jin-Hyuk , Kang In Man
Published: March 2021

In this paper, we present a capacitorless one transistor dynamic random access memory (1T-DRAM) based on a polycrystalline silicon (poly-Si) double gate MOSFET with grain boundaries (GBs). Several studies have been conducted to implement 1T-DRAM using poly-Si. This is because poly-Si
has the advantage of low-cost fabrication and can be stacked. However, poly-Si has GBs, which can adversely affect semiconductor device. So far, related studies on poly-Si-based 1T-DRAM have only focused on GBs present in the channel domain. Hence, in this study, we analyzed the transfer and
memory characteristics when a GB is present in the source and drain regions. As a result, we found that in the center of the depletion region in the source and channel junction, where the effect of GB was most significant, sensing margins decreased the most from 0.88 to 0.29 μA/μm,
and retention time (RT) decreased from 85 ms to 47 μs. In addition, we found that at the center of the depletion region in the drain and channel junction, where the effect of GBs was most significant in the drain region, RT decreased the most from 85 ms to 52 μs.
Steep Switching Characteristics of Partially Gated p+–n+–i–n+ Silicon-Nanowire Transistors
Authors: Son Jaemin , Lim Doohyeok , Kim Sangsig
Published: March 2021

In this study, we examine the electrical characteristics of p+–n+–i–n+ silicon-nanowire field-effect transistors with partially gated channels. The silicon-nanowire field-effect transistors operate with barrier
height modulation through positive feedback loops of charge carriers triggered by impact ionization. Our field-effect transistors exhibit outstanding switching characteristics, with an on current of ˜10−4 A, an on/off current ratio of ˜106, and a point
subthreshold swing of ˜23 mV/dec. Moreover, the devices inhibit ambipolar characteristics because of the use of the partially gated structure and feature the p-channel operation mode.
Effect of Ge Mole Fraction on Performance of Underlapped Gate-All-Around SiGe-Source Tunneling Field-Effect Transistors
Authors: Jeon Juhee , Park Young-Soo , Woo Sola , Lim Doohyeok , Son Jaemin , Kim Sangsig
Published: March 2021

In this paper, we propose the design optimization of underlapped Si1–xGex-source tunneling field-effect transistors (TFETs) with a gate-all-around structure. The band-to-band tunneling rates, tunneling barrier widths, I–V transfer
characteristics, threshold voltages, on/off current ratios, and subthreshold swings (SSs) were analyzed by varying the Ge mole fraction of the Si1–xGex source using a commercial device simulator. In particular, a Si0.2Ge0.8-source
TFET among our proposed TFETs exhibits an on/off current ratio of approximately 1013, and SS of 27.4 mV/dec.
Characteristics of Perovskite Solar Cells with Methylammonium Iodide-Added Anti-Solvent
Authors: Joo Sung Hwan , Kim Il Tae , Choi Hyung Wook
Published: March 2021

The perovskite film—manufactured via a one-step method—was superficially improved through an anti-solvent process to increase solar cell efficiency. Although perovskite synthesis proceeds rapidly, a significant amount of lead iodide residue remains. Well-placed lead iodide
in perovskite grains prevents electron–hole recombination; however, when irregularly placed, it interferes with the movement of electron and holes. In this study, we focused on improving the crystallinity of the perovskite layer, as well as reducing lead iodide residues by adding a methylammonium
halide material to the anti-solvent. Methylammonium iodide in chlorobenzene used as an anti-solvent reduces lead iodide residues and improves the crystallinity of formamidinium lead iodide perovskite. The improved crystallinity of the perovskite layer increased the absorbance and, with reduced
lead iodide residues, increased the efficiency of the perovskite solar cell by 1.914%.
Characteristics of Perovskite Solar Cells (PSCs) with Various Metal Electrode Deposited Using Thermal Evaporators
Authors: Kim Sangmo , Lee Shin Kyu , Hwang Ji Yong , Kim Maro , Choi Hyung Wook , Bark Chung Wung
Published: March 2021

Organic material-based solar cell devices such as perovskite solar cells (PSCs) have attracted attention as renewable energy resources with low production cost, lightweight, wearable device applications, and large-area processability. To enhance device performance, many research groups
have attempted to develop new materials and structures. Metal electrode materials play an important role in solar energy conversion in PSCs, owing to the ohmic contact and contact resistance between metal negative electrodes and photoactive layers. Until recently, conventional metal sources
such as Ag, Au, or Cu have been used as electrodes. In this study, PSCs were employed in various metal negative electrodes using a thermal evaporator. The authors investigated the effect of metal negative electrodes on PSCs.
Study on Effects of Carrier Gas Flow Rate on Properties of Low Dielectric Constant Film Deposited by Plasma Enhanced Chemical Vapor Deposition Using the Octamethylcyclotetrasiloxane Precursor
Authors: Park Yoonsoo , Lim Hyuna , Baek Namwuk , Park Seung Hun , Lee Sungwoo , Yang Jeayoung , Jung Donggeun
Published: March 2021

In semiconductor industry, low-dielectric-constant SiCOH films are widely used as inter-metal dielectric (IMD) material to reduce a resistance-capacitance delay, which could degrade performances of semiconductor chips. Plasma enhanced chemical vapor deposition (PECVD) system has been
employed to fabricate the low-dielectric-constant SiCOH films. In this work, among various parameters (plasma power, deposition pressure, substrate temperature, precursor injection flow rate, etc.), helium carrier gas flow rate was used to modulate the properties of the low-dielectric-constant
SiCOH films. Octamethylcyclotetrasiloxane (OMCTS) precursor and helium were injected into the process chamber of PECVD. And then SiCOH films were deposited varying helium carrier gas flow rate. As helium carrier gas flow rate increased from 1500 to 5000 sccm, refractive indices were increased
from 1.389 to 1.428 with enhancement of mechanical strength, i.e., increased hardness and elastic modulus from 1.7 and 9.1 GPa to 3.3 and 19.8 GPa, respectively. However, the relative dielectric constant (k) value was slightly increased from 2.72 to 2.97. Through analysis of Fourier
transform infrared (FTIR) spectroscopy, the effects of the helium carrier gas flow rate on chemical structure, were investigated. It was thought that the increase in helium carrier gas flow rate could affect the density with changes of chemical structure and composition. In conclusion, regulation
of helium carrier gas flow rate can effectively modulate k values and mechanical strength, which is needed for IMD material in semiconductor fabrication possess.
Plasma Polymerized SiCOH Films from Octamethylcyclotetrasiloxane by Dual Radio Frequency Inductively Coupled Plasma Chemical Vapor Deposition System
Authors: Lim Hyuna , Park Yoonsoo , Baek Namwuk , Jun So-Yeon , Lee Sungwoo , Yang Jeayoung , Jung Donggeun , Yu SeGi
Published: March 2021

We have fabricated porous plasma polymerized SiCOH (ppSiCOH) films with low-dielectric constants (low-k, less than 2.9), by applying dual radio frequency plasma in inductively coupled plasma chemical vapor deposition (ICP-CVD) system. We varied the power of the low radio frequency
(LF) of 370 kHz from 0 to 65 W, while fixing the power of the radio frequency (RF) of 13.56 MHz. Although the ppSiCOH thin film without LF had the lowest k value, its mechanical strength is not high to stand the subsequent semiconductor processing. As the power of the LF was increased,
the densities of ppSiCOH films became high, accordingly high in the hardness and elastic modulus, with quite satisfactory low-k value of 2.87. Especially, the ppSiCOH film, deposited at 35 W, exhibited the highest mechanical strength (hardness: 1.7 GPa, and elastic modulus: 9.7 GPa),
which was explained by Fourier transform infrared spectroscopy. Since the low-k material is widely used as an inter-layer dielectric insulator, good mechanical properties are required to withstand chemical mechanical polishing damage. Therefore, we suggest that plasma polymerized process
based on the dual frequency can be a good candidate for the deposition of low-k ppSiCOH films with enhanced mechanical strength.
Effects of Annealing on an IGZO-Metal Interface
Authors: Yu Eun Seong , Kang Seok Jun , Lee Jong Mo , Bae Byung Seong
Published: March 2021

The interface reaction between a metal layer and a layer of amorphous indium-gallium-zinc oxide was investigated. Oxygen atoms at the interface bond to the metal atoms and form metal oxide. The reaction depends on the annealing temperature and ambient conditions. The thickness of the
metal oxide at the interface increased with the annealing temperatures. The reaction relies on the Gibbs free energy for oxidation. Ta, which has low Gibbs free energy formed a 33 nm layer of tantalum oxide at an annealing temperature of 450 °C. The HR-TEM and EDX observation showed that
the metal oxide thicknesses were 5, 10, and 33 nm at annealing temperatures of 350, 400, and 450 °C, respectively. The thicknesses obtained with both Ar and oxygen gas were 4, 8, and 21 nm, respectively. The lower oxide thicknesses were attributed to the lower number of oxygen vacancies
in the IGZO deposited using Ar and oxygen, which was identified by XPS analysis.
Functionalized Mesoporous Silica for Highly Selective Sensing of Iron Ion in Water
Authors: Park Sung Soo , Kong Jungwon , Selvaraj Manickam , Ha Chang-Sik
Published: March 2021

In this study, we examined the highly selective sensing of Fe3+ ions in water using metal complex-functionalized mesoporous silica materials. Metal complex-functionalized mesoporous silica materials were synthesized on the mesoporous surface of SBA-15 via complexation process
between Eu3+ and aminosilane groups. Mesoporous silica, SBA-15, and the Eu3+-complex functionalized SBA-15 were characterized using X-ray diffraction (XRD), transmittance electron microscopy (TEM), nitrogen sorption behavior, and Fourier transform infrared (FTIR) spectroscopy.
The sensing behavior of the Eu3+-complex functionalized SBA-15 was studied using various metal ions (Fe3+, Cu2+, Cr3+, Co2+, Hg2+, Pb2+, and Zn2+) aqueous solutions. Photoluminescence intensity (λ
= 612 nm) of the Eu3+-complex functionalized SBA-15 was dependent on the different interactions between metal ions and Eu3+-complexes. Photoluminescence intensity at λ = 612 nm of the Eu3+-complex functionalized SBA-15 decreased to near zero and
proved the highly selective sensing effect of Fe3+. Therefore, the Eu3+-complex functionalized SBA-15 can be considered an excellent candidate for sensing iron ions in water.
Copolymerization of Acrylic Monomers and Silane Group Containing Titanium Carbide Nanoparticles for Application to Ophthalmic Lens Materials
Authors: Lee Min-Jae , Sung A-Young
Published: March 2021

This research was conducted to synthesis and application for high oxygen permeable ophthalmic lens materials. 2-(Trimethylsiloxy)ethyl methacrylate (2T), 3-[Tris(trimethylsiloxy)silyl]propyl methacrylate (3T), [(1,1-Dimethyl-2-propynyl)oxy]trimethylsilane (TMS), Poly(ethylene glycol)
methyl ether methacrylate (PEGMA), N-vinyl-2-pyrrolidone (NVP) and titanium carbide nanoparticles were used as additives for the basic combination of synthesized silicone monomer (SiD) and N,N-Dimethylacetamide (DMA). And also, the materials were copolymerized with ethylene glycol dimethacrylate
(EGDMA) as the cross-linking agent, azobisisobutyronitrile (AIBN) as the initiator. The copolymerization with a small amount of silane of about 1% increased the oxygen permeability to 30.3˜33.52(cm2/sec)·(mlO2/ml·mm Hg)·10−11,
and in particular, the addition of titanium carbide nanoparticles was found to increase to 46.38 (cm2/sec)·(ml O2/ml·mm Hg)·10−11. Surface modification was possible with various wetting agents. Especially, simultaneous use with titanium
carbide nanoparticles increased the wettability while maintaining water content. These materials are considered to make synergy effect each other, so it can be used in functional hydrogel ophthalmic lenses.
Theoretical Study of Triphenylphosphine Oxide Derivatives for Blue Thermally Activated Delayed Fluorescence
Authors: Lee Sae Won , Kim Young Sik
Published: March 2021

We designed novel thermally activated delayed fluorescence (TADF) materials by combining the electron donor 10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azasiline (DDA) with the electron acceptor triphenylphosphine oxide (PO) unit (mDDA-PO and o-mDDA-PO) and compared their characteristics
with those of a reference material using 1,3-Bis(N-carbazolyl)benzene (mCP) as an electron donor (mCP-PO) for blue organic light-emitting diodes (OLEDs). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distributions of the highest occupied
molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) as well as the energies of the lowest singlet (S1) and lowest triplet (T1) excited states. The calculated energy difference (ΔEST) between the S1 and T1
states of mDDA-PO (0.16 eV) and o-mDDA-PO (0.07 eV) were smaller than that of mCP-PO (0.48 eV). The results showed that o-mDDA-PO is a suitable blue OLED emitter because it has sufficiently small ΔEST values, which is favorable in a reverse-intersystem process crossing
from the T1 state to S1 states, as well as an emission wavelength of 446.7 nm.