Ligen Yu

Nanyang Technological University | ntu · Talent Recruitment And Career Support (TRACS) Office and Bibliometrics Analysis

Morbid obesity and anorexia nervosa (AN) are serious health problems with devastating consequences. Nevertheless, the aetiology of them is still elusive. By natural weight loss, one of the authors of this paper experienced a process from overweight to AN. And by adopting the anorexic Luigi Cornaro diet, he recovered from AN. Based on his unique exp...

Modern medicine is divided into different specialties. While well-trained experts can serve the patients better, each medical specialty is isolated to itself. For example, it is a norm for gastroenterology that fasting can lead to gastrointestinal tract (GIT) mucosa atrophy, and make the patient prone to bacterial translocation and sepsis. Yet, phy...

Special Issue Information https://www.mdpi.com/journal/biology/special_issues/Z3R7F21R34 Dear Colleagues, Immunologists have long been puzzled by the self-destructive nature of the inflammatory response. Inflammation can be elicited by various harmful stimuli, such as microbial/viral infections, allergic reactions, chemical insults, lipotoxicity...

Amid an increasingly demanding research environment, there has been a growing interest in studies concerning Research Integrity and Research Ethics (RIRE). Between 1990 and 2020, over 9700 publications were published to address problematic research conduct such as falsification, plagiarism, and related protocols and standards. In this work, country...

Luigi Cornaro in his four discourses (The Art of Living Long. Milwaukee. Butler WF. 1905, http://hdl.handle.net/2027/nnc2.ark:/13960/t1sf3j34q), repeatedly pointed out that a sober and temperate life consists of two rules: quality and the quantity. Quality is eating and drinking only such things as agree with the stomach; quantity is only consuming...

Review Report for "Evidence and Therapeutic Perspectives in the Relationship between the Oral Microbiome and Alzheimer’s Disease: A Systematic Review" published by Int J Environ Res Public Health 2021, 18(21), 11157; https://doi.org/10.3390/ijerph182111157 (registering DOI)

Since birth, human beings are in close contact with the microbial environment, live with the microbiota on and inside the human body and develop a symbiotic relationship with them in a mutually beneficial/defensive way. The human immune system is also developed during this process. It is a multi-level, multi-purpose complex system with many redunda...

The human immunity has a pivotal role in nutrition acquisition from the pathogens and damaged body tissue during the SARS-CoV-2 virus infection, which may lead to transient overnutrition in the patients, lead to lipotoxicity and further damage in non-adipose tissues, and cause hyperinflammation and cytokine storm in severe cases of COVID-19. In vie...

Review Report for "The Role of the Oral Microbiota in the Etiopathogenesis of Oral Squamous Cell Carcinoma" published in Microorganisms

Global publication trends in research integrity and research ethics (RIRE) have increased exponentially. Over 25,700 publications on RIRE from Web of Science across the period 1990-2018 form the basis of this study. Countries, institutions, and their collaborations on RIRE are analyzed. Results show that developed countries in North America and Wes...

COVID-19 continues to be an ongoing global threat. The elderly with underlying health conditions like cardiovascular and lung diseases, diabetes, obesity, are the most vulnerable to this disease. Curing the pre-existing health conditions will greatly increase a person’s resilience to COVID-19 and lower the death rate of the old people. Digestion an...

Thermal barrier coating (TBC) systems reduce the temperature of the metallic substrate of aerospace engines, resulting in improved component durability, better fuel economy and performance. Scientific research and innovation on TBC systems evolves rapidly and diversely over the years. Hence, an understanding of the research and innovation pathways...

{I'm not the author or editor of this book. Just helping the editors to distribute this book to people who need it. Thanks! -- Ligen YU} Editor’s Note: Faced with an unknown virus, sharing and collaboration are the best remedy. The publication of this Handbook is one of the best ways to mark the courage and wisdom our healthcare workers have dem...

Human beings have co-evolved with the microorganisms in our environment for millions of years, and have developed into a symbiosis in a mutually beneficial/defensive way. Human beings have significant multifaceted relationships with the diverse microbial community. Apart from the important protective role of microbial community exposure in developm...

Thermal barrier coating (TBC) systems reduce the temperature of the metallic substrate of modern gas turbines, resulting in improved component durability and increased efficiency. This study examine the research publications and patents on thermal barrier coating in Scopus and USPTO patent database, respectively, during the period 19812018. Bibliom...

Objective: Nanyang Technological University, Singapore set up an Institutional Review Board (IRB) in 2010. This presentation reports the analysis of over 3400 projects approved by the NTU Institutional Review Board (NTU-IRB) during the period 2010-2018 to identify potential risks related to research integrity. Method: Heat maps are generated throug...

Objective: This paper reports the trends of global publications on research integrity and research ethics. The primary aim is to highlight the common focus as well as differences in emphasis among the countries. Method: Publications on research integrity, research ethics, academic integrity and academic ethics in the period 1990-2018 from the Web o...

Anorexia nervosa (AN) is a serious health problem. Despite the highly destructive consequences of AN, the etiology of AN is still unclear. Here we report a case of adult male patient who developed AN by eating irregularly and fasting for weight loss, and recovered from AN by adopting the Luigi Cornaro diet. Since then, he has followed this diet for...

Many studies show that infection-induced anorexia (IIA) as an active host defence strategy promotes health recovery during an infection.[1] IIA belongs to the atypical anorexia that are not induced by mental disorder, and should not be confused with anorexia nervosa (an eating disorder). It is atypical because the host generally has a normal weight...

We investigated the research publications on thermal spray in the period of 1985-2015 using the data from Web of Science, Scopus and SciVal®. Bibliometrics analysis was employed to elucidate the country and institution distribution in various thermal spray research areas and to characterize the trends of topic change and technology progress. Result...

We investigated the effect of international collaboration (in the form of international co-authorship) on the impact of publications of young universities (<50 years old), and compared to that of renowned old universities (>100 years old). The following impact indicators are used in this study, they are: (1) the 5-year citations per paper (CPP) dat...

It is widely assumed that research collaboration, especially international collaboration, has benefits for both the researchers and the organisations involved, and enhances the quality of research (Van den Besselaar et al., 2012). However, research also suggests that the effects of international collaboration may vary across disciplines and the aut...

In the last two decades, Singapore has successfully moved from the process of building a nation to becoming a global city truly embracing the concept of knowledge-based economy. Nanyang Technological University (NTU) as a relatively young university (established in 1991) has a unique role and position in Singapore's academic ecosystem. As NTU has u...

Control of competing parameters such as thermoelectric (TE) power and electrical and thermal conductivities is essential for the high performance of thermoelectric materials. Bulk-nanocomposite materials have shown a promising improvement in the TE performance due to poor thermal conductivity and charge carrier filtering by interfaces and grain bou...

The major hurdle that limits extensive application of thermal sprayed WC–Co coatings is the undesirable phase changes from WC to W2C or even W due to loss of carbon. This study investigated quantitatively the decarburization of WC in both in-flight and coating formation stages during atmospheric plasma spraying. The microstructure evolution of WC p...

This work aims to find an efficient sintering technique and optimal sintering conditions of a novel sol–gel derived Bioglass®-ceramic powder so as to achieve much improved mechanical properties compared to conventional Bioglass®. To this end, the spark plasma sintering (SPS) technique was for the first time used to densify the sol–gel derived Biogl...

We report on the enhanced thermoelectric properties of selenium (Se) doped bismuth telluride (Bi(2)Te(3-x)Se(x)) nanoplatelet (NP) composites synthesized by the polyol method. Variation of the Se composition within NPs is demonstrated by X-ray diffraction and Raman spectroscopy. While the calculated lattice parameters closely follow the Vegard's la...

Numerous sintering studies have been published concerning the innovative Spark-Plasma-Sintering (SPS) procedure during the last years. A wide variety of materials (such as oxidic and non-oxidic ceramic powders, metal and composite samples) with different particle size (submicron and nanoscale), various electric, thermal, and mechanic properties hav...

The spark-plasma-sintering (SPS) method was used for sintering of different tungsten carbide (WC) and titanium carbonitride (TiCN) nanopowders obtained by the method of plasma synthesis. Dense, fine-grained monophase materials (WC and TiCN) were obtained at relatively low temperatures. Obtained results were compared with that for hot pressing (HP)...

Boriding (or boronizing) is an important thermochemical surface treatment used to enhance the surface hardness and wear resistance of ferrous and non-ferrous alloy components. The metal boride compounds formed exhibit higher hardness values, increased chemical inertness, and improved service life of the component. Nickel-base alloys are commonly us...

Alumina micro-channel parts were produced by micro powder injection molding. The debound part was rapidly densified by pressuresless spark plasma sintering. Rapid densification of the micro-channel part proved to be feasible. Good shape retention and high densification were achieved for the final micro-channel part. The microstructural analysis rev...

Although methods of measuring the elastic properties of thin films have made great advances with the use of bulge testing of membranes, deflection of micromachined beams, and nanoindentation, most results are still being compared to either isotropic or single crystal elastic constants, neither of which are, in general, appropriate for textured poly...

The low temperature sintering behaviour of nanocrystalline Ag powder (with an average size of 70 nm) was characterized. Using spark plasma sintering (SPS), the Ag nanopowders can be successfully sintered at low pressure for only 5 min without external heating, and the sintering density increases and porosity decreases significantly with increase in...

A novel polyether binder-assisting (PBA) method was used to disperse CNTs into aluminum (Al) matrix, and a 0.5 wt.% CNTs reinforced Al composite was processed by powder metallurgy (PM) technique. The CNTs were almost not damaged during PBA-mixing. The tensile strength of the composite reached 195 MPa, with minor decreased ductility by comparison wi...

Ruthenium samples with a cylindrical shape have been prepared by means of the Spark-Plasma-Sintering (SPS) process at sintering temperatures between 1200 °C and 1600 °C and a corresponding sintering time of 1 min. Similar samples were obtained by conventional hot-pressing process methods at 1200 °C and 1400 °C for 60 min. The residual stress compon...

Spark-plasma-sintering (SPS) experiments of cylindrical ruthenium powder samples have been performed at different sintering temperatures between 1200°C and 1600°C applying a comparatively short sintering time of 1min. The compacted samples have been characterized in respect of crystallite size, phase composition, and microstructure by X-ray diffrac...

Hydroxyapatite-reinforced nanocomposites with titania nanocrystals addition are prepared by a homogeneous mixing of hydroxyapatite nanoparticles and titania nanocrystals based on high-energy ball milling and spark plasma sintering processes. The microstructural and mechanical properties of the HA/titania composites are studied by X-ray diffractomet...

A study was conducted to demonstrate the preparation of hydroxyapatite (HA)-reinforced nanocomposites with the addition of nanocrystalline TiO 2 powders by combining high-energy ball milling with spark plasma sintering (SPS) processes. The effects of TiO2 molar content and the sintering temperature on the phase composition, microstructure, mechanic...

Tantalum samples have been compacted by the spark-plasma-sintering (SPS) sintering method. The sintering experiments have been conducted at temperatures between 1500 °C and 1900 °C and corresponding sintering times of 1 min each. The compacted samples of cylindrical shape have been characterized in respect of their residual stress by X-ray diffract...

Mild steel samples were borided with and without boron pack refreshment using the spark plasma sintering (SPS) process. Results show that the borided samples with boron pack refreshment developed a thicker boride layer compared to that without boron pack refreshment for the same boriding duration. When boriding duration is t<120 min, the boriding g...

The spark plasma sintering behaviour of silver nanopowder prepared by the electro-explosion method was investigated. Consolidation was carried out from 50°C to 800°C for 5 mins at 34 MPa with differential scanning calorimetry indicating a sintering onset temperature as low as 160°C and an activation energy of 86+/-1 kJ/mol. Near full density result...

Spark-plasma-sintering (SPS) is a compaction method whereby pulsed current is applied using a similar setup as conventional hot pressing. SPS experiments of tantalum powder samples have been performed at different sintering temperatures between 1500°C and 1900°C applying a comparatively short sintering time of 1min. The compacted samples have been...

In general the sintering of copper powder compacts is conducted under reducing atmosphere to avoid additional oxidation and to reduce remaining oxides from the starting powders. The oxide content varies depending on the size of the starting powders. In this work we performed sintering experiments under vacuum conditions with copper powders of diff...

Molybdenum borides have potential industrial applications as abrasive, corrosion-resistant and electrode materials due to their high hardness values, chemical inertness, and electronic conductivity. In this work, boride layers are formed on the surface of Mo samples using a pack boriding method with the assistant of the spark plasma sintering (SPS)...

Spark plasma sintering (SPS) pack-boriding of mild steel was carried out at relatively low temperatures (600C to 700C) for different holding time durations. The microstructure of the boride layer was inspected by scanning electron microscopy (SEM), and the phase composition was inspected by X-ray diffraction (XRD). The correlation between the borid...

Commercial submicron copper powder samples with different particle size have been sintered by Spark-Plasma-Sintering (SPS) and by inductive heated hot pressing. The occurrence of the spark-plasma effect should be determined by comparing the results of the SPS experiments with reference data obtained by rapid inductive heated hot pressing experiment...

本发明公开了一种薄壁零件在激光熔覆、热喷涂及焊接加工中的局部高效冷却方法。

Molybdenum borides are known to have high hardness values, chemical inertness, and electronic conductivity, and have potential industrial applications as abrasive, corrosion-resistant and electrode materials, which are exposed to exacting environments. In this work, boride layers are formed on the surface of Mo samples using a pack boriding method...

Zirconium boride (ZrB2) has attracted substantial interest for its high corrosion resistance, high electrical and thermal conductivity and high hardness and strength at high temperatures. The formation of zirconium borides on zirconium metal surface was studied in the temperature range 850C-1200C using the spark plasma sintering boriding (SPS-Bor...

Spark-plasma-sintering (SPS) compaction experiments of nanostructured titanium carbonitride powders have been performed at 1600 °C and 1800 °C (sintering time = 1 min). The as-received nanostructured powders have been synthesized through rapid condensation from the gas-phase (high frequency plasma). The sintering results were compared with data obt...

The iron boride layer growth kinetics in mild steel through the spark plasma sintering (SPS) pack-boriding technique is investigated at 850 °C with different boriding durations (maximum 240 min). Results show that both FeB and Fe2B layers form and grow on the mild steel surface with the FeB layer on the top of Fe2B sublayer in the samples with bori...

The high sintering temperature required for aluminum nitride (AlN) at typically 1800°C, is an impediment to its development as an engineering material. Spark plasma sintering (SPS) of AlN is carried out with samarium oxide (Sm2O3) as sintering additive at a sintering temperature as low as 1500–1600°C. The effect of sintering temperature and SPS cyc...

Metal borides are attractive candidates for high-temperature, wear resistance, and corrosion resistance applications. Tungsten borides (WB and W2B5) are known to have high hardness values, chemical inertness, and electronic conductivity, and have potential industrial applications as abrasive, corrosion-resistant and electrode materials, which are e...

Thermal sprayed tungsten carbide (WC)–cobalt (Co) coatings have been extensively employed as abrasion/wear protective layers. However, carbon loss (decarburization) of WC–Co powders during thermal spraying reduces the efficiency of the coatings against abrasive wear. Post-spray treatment with spark plasma sintering (SPS) technique was conducted on...

Spark plasma sintering of Ti50Ni50 nano-powder at a temperature of 800 °C produced specimens showing good shape memory effect and density. Below this temperature, specimens have high porosity but with apparent shape memory effect. By contrast, the specimens sintered at higher temperatures have bulk density, but experienced extensive oxidation with...

The formation and re-melting of the melilite solid solution phase (M’) was studied as a function of temperature in the range of 1300-1550C using spark plasma sintering (SPS) method. The SPS is carried out in the stated temperature range with a soaking time of 3 minutes at each temperature. X-ray diffraction was employed to investigate the phase co...

Yttrium stabilised zirconium oxide powders (YSZ) have been synthesized from an aqueous solution of a stoichiometric mixture of yttrium nitrate and zirconium oxychloride and subsequent precipitation by ammonia. Commercial YSZ material was used as a reference sample. A pulsed electric current is applied directly to the graphite mold and the sample du...

The preparation of ultrafine tungsten carbide bulk solids is of a more general interest in respect of the increased mechanical properties of such materials. Nanostructured tungsten carbide powders have been synthesized by ultra-rapid condensation from a high-frequency plasma. Commercial powder samples with a grain size (0.7 micrometer grain size) a...

Spark plasma sintering of Cu nano powder at 600C.

Spark-plasma-sintering (SPS) consolidation of submicron and nanostructured titanium oxide (TiO2) powders was performed between 800 and 1000 °C for 1 min. The results were compared with conventional sintering using electrical resistant furnace that was performed between 600 and 1000 °C for 120 min. The compacted samples were investigated by X-ray di...

SEM Pictures for mild steel borided at 850C for 4 hours plus 1 hour refreshment.

The alleviation of SiO2 as contaminant in SOFC electrolyte was studied through spark plasma sintering (SPS) of yttria-stabilized zirconia (YSZ) doped with ∼0.5wt.% SiO2. The outcome of variations in SPS process conditions such as sintering temperature, duration, and applied pressure on the grain boundary and grain interior resistivity of silica-dop...

Several Spark-Plasma-Sintering (SPS) compaction experiments of nanostructured and conventional titanium carbonitride powders of various stoichiometric composition (C/N ratio) have been performed at different sintering conditions. The nanostructured samples have been synthesized by ultra-rapid condensation from the gas phase in a high frequency plas...

Decarburization of WC–Co is a common phenomenon during atmospheric plasma spray (APS) deposition, resulting in a large amount of W2C and other carbon-deficient phases in the coating. Consequently, the properties and performance of the coating may be inadequate and unreliable. In this study, spark plasma sintering (SPS) is applied as a post-spray he...

Plasma spraying is a fast and inexpensive process for fabricating YSZ electrolyte for SOFCs. In this investigation, free-standing plasma sprayed YSZ disks are treated by spark plasma sintering at different temperatures, soak times, and loading cycles. SEM examination shows that the lamellar microstructure of the as-sprayed zirconia is converted to...

Spark plasma sintering (SPS) was adopted in this study as a rapid post-spray treatment for 20 wt.% yttria stabilized zirconia (YSZ) electrolytes prepared by the direct current (DC) plasma spray process. The lamellar microstructure in the as-sprayed samples was found to significantly reduce the ionic conductivity of the YSZ electrolytes. However, th...

Thermal sprayed chromium carbide (CrC) coatings are used successfully to extend component lifetimes in a wide range of wear environments due to their excellent hardness and wear resistance, even at high temperatures or in corrosive environment. The high reproduction of parts concurrent with low cost has made plasma spray one of the best options in...

Thermal sprayed chromium carbide (CrC) coatings are used successfully to extend component lifetimes in a wide range of wear environments due to their excellent hardness and wear resistance, even at high temperatures or in corrosive environments. The high reproduction of parts concurrent with low cost has made plasma spray one of the best options in...

Thermal sprayed WC-Co coatings have been extensively employed as abrasion/wear protective layers. However, carbon loss (decarburization) of WC-Co powders during thermal spraying reduces the efficiency of the coatings. Spark plasma sintering (SPS) post-spray treatment was conducted for plasma sprayed WC-Co coatings in the present study aiming to com...

The bimodal sized HA powders, which contained nano and micro particles together, were obtained through radio frequency (RF) plasma process. The effect of different sintering temperature on bimodal sized HA powders were examined through spark plasma sintering (SPS) method. Analysis of powders using SEM illustrated that hollow structure was formed du...

Spark-Plasma-Sintering (SPS) compaction experiments of nanostructured titanium carbonitride powders have been performed at 1600°C and 1800°C (sintering time 1 min). The results were compared with data obtained by various conventional sintering techniques: pressureless sintering, gas pressure sintering, and hot pressing. The compacted samples were i...

Solid oxide fuel cells (SOFC) are promising candidates for alternative power generation systems due to their high-energy conversion efficiencies, and low emissions of environmentally hazardous by-products. Plasma spray (PS) is an effective, and relatively inexpensive process for fabricating high performance yttria stabilized zirconia (YSZ) electrol...

Cell wall of stainless steel randomly packed hollow sphere structures (RHS) were densified by spark plasma sintering (SPS) in the temperature range 1000–1200°C. The porosity of RHS cell wall before and after SPS are inspected by quantitative image analysis of scanning electron microscope (SEM) micrographs. The micro-indentation technique examines t...

The crystalline phases and degree of crystallinity in plasma sprayed calcium phosphate coatings on Ti substrates are crucial factors that influence the biological interactions of the materials in vivo. In this study, plasma sprayed hydroxyapatite (HA) coatings underwent post-spray treatment by the spark plasma sintering (SPS) technique at 500 degre...

Aluminum nitride (AlN) possesses excellent properties for use as a substrate or packaging material in the flourishing microelectronics industry. However, AlN is exceptionally difficult to sinter through conventional sintering processes, and pure AlN does not attain full density even at sintering temperatures above 1800 °C. In this study, pure AlN a...

Miscellaneous sintering conditions of spark-plasma sintering (SPS) were investigated to obtain high-density yttria-stabilized zirconia (YSZ) electrolytes for solid oxide fuel cells (SOFC). Nano-size YSZ raw powder (50 nm) was densified to a relative density of 99.1% at 1400 °C, with an applied uniaxial pressure of 23 MPa, and a total of four consec...

Mullite–zirconia ceramic composites are prepared by reaction sintering of plasma spheroidized (PS) zircon–alumina powders in a spark plasma sintering (SPS) system at 1000, 1100, 1200 and 1300 °C with duration of 10 and 30 min. At SPS temperature of 1000 °C, evidence of zircon decomposition is detected, while at 1200 °C, mullite formation dominates...

HA(Hydroxyapatite) coatings on metals (commonly Ti alloys) is widely used for dental and orthopedic implants because of the unique bio-active properties of the coatings. Plasma spray (PS) is the only method that has been used to deposit HA coatings on implants that are in clinical use. Post spray treatment is needed to modify the microstructure of...

Yttria-stabilized zirconia (YSZ) electrolytes with diverse microstructures were prepared by using nano-size (Y2O3)0.08(ZrO2)0.92 powders as precursors through conventional sintering in air. The electrolytes were tested by AC impedance spectroscopy to elucidate the contribution of intragranular and intergranular conductivity to the total ionic condu...

The spark plasma sintering (SPS) technique was employed to perform boriding of mild steel. A pack boriding method that contained a silicon carbide–boron carbide powder pack mixture was utilized in this study. The process was performed in the temperature range 700–1000 °C for 30 min. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) rev...