bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of elevation on the species–area relationship
Authors: Moradi Halime , Fattorini Simone , Oldeland Jens
Published: April 2020

Aim

Species–area relationships (SARs) are among the best investigated patterns in ecology, yet the shape of the function that should describe SARs and the biological meaning of the function parameters are disputed. Elevational gradients offer the opportunity of investigating how biodiversity responds to large variations in environmental characteristics within small geographical areas. We asked which function describes SARs at different elevations and explored how variations in environmental characteristics influence SAR shape.

Location

Alborz Mountains (Iran).

Taxon

Vascular plants.

Methods

We used sets of nested plots (0.001 to 100 m2) placed at 100 m intervals from 2,000 to 4,500 m elevation to construct series of nested SARs as species accumulation curves. Then, we used these curves to assess the appropriateness of different SAR functions at different elevations. We investigated how parameters of the power function varied along the elevational gradient in response to variation in environmental parameters (ruggedness, temperature, precipitation, exposed rock, percentages of soil sand and total nitrogen, and productivity, expressed by the normalized difference vegetation index).

Results

The most frequently observed best fit model was the power function, which is controlled by two parameters: z (the velocity in species accumulation with sampled area) and c (the species richness per unit area). z was positively influenced by temperature and soil nitrogen, decreasing with elevation. c was positively influenced by temperature and soil nitrogen, and negatively by rock cover, decreasing with elevation.

Main conclusions

The decrease in c‐values with elevation is consistent with the altitudinal decrease in species richness and is explained by the increase in bare rock. By contrast, c was positively influenced by temperature and total nitrogen, which are two factors promoting plant growth. Similarly, z‐values decreased with elevation, thus indicating a decrease in beta diversity.
Soft tissue stability around dental implants after soft tissue grafting from the lateral palate or the tuberosity area – A randomized controlled clinical study
Authors: Rojo Ernest , Stroppa Giorgio , Sanz‐Martin Ignacio , Gonzalez‐Martín Oscar , Nart Jose
Published: April 2020

Aim

To compare the soft tissue stability (STA) around single implants previously augmented with either subepithelial connective tissue graft (SCTG) from the lateral palate (LP) or from the tuberosity area (TA).

Material and Methods

Twenty‐nine patients showing 33 implants with buccal volume deficiency randomly received SCTG from LP (control group/CG) or TA (test group/TG). At 4 months (FU‐4) the definitive crown was installed and an intra‐oral scan performed. At 12 months (FU‐12), a new scan was registered. Between FU‐4 and FU‐12 STA was evaluated by STL image superimposition. Clinical parameters and the modified pink aesthetic score (PES) (Fürhauser et al. 2005) were recorded.

Results

After FU‐4 both tissues demonstrated a similar STA without statistically significant differences (SSD). The mean soft tissue changes were 0.03 ± 0.22 mm for CG and 0.04 ± 0.23 mm for TG (p = .870). SSD were observed for changes in keratinized tissue (KT) with greater stability for TG (0 ± 0.32 mm) compared with CG (−0.3 ± 0.33 mm) (p = .002). PES resulted in mean values of 8.37 ± 2.46 for CG and 8.54 ± 2.43 for TG (p=.59).

Conclusions

Both groups demonstrated similar STA between the definitive crown placement and 12 months, while greater stability of the KT gained was observed in TG.
Leucocyte‐ and platelet‐rich fibrin regulates expression of genes related to early wound healing in human gingival fibroblasts
Authors: Bi Jiarui , Intriago Maria Fernanda Barona , Koivisto Leeni , Jiang Guoqiao , Häkkinen Lari , Larjava Hannu
Published: April 2020

Background

Leucocyte‐ and platelet‐rich fibrin (L‐PRF) is a blood‐derived biomaterial rich in leucocytes and platelets embedded in a high‐density fibrin network that can be compressed into a membrane and used in surgical applications to stimulate tissue regeneration and wound healing, especially in oral cavity. This study aimed to determine the combined effects of the growth factors and cells present in L‐PRF on fibroblasts that directly face the L‐PRF membranes placed during surgical procedures.

Methods

The effect of L‐PRF from six donors on the expression of 84 key wound healing genes in normal human gingival fibroblasts was tested by RT‐qPCR.

Results

L‐PRF significantly regulated the expression of 33 fibroblast genes (39%), including interleukins, myofibroblast‐, extracellular matrix‐ and angiogenesis‐associated genes, and matrix metalloproteinase‐1 and −3. L‐PRF regulated fibroblast gene expression both time‐ and dose‐dependently, and the effects were mediated by mitogen‐activated protein kinases ERK1/2, JNK and p38. L‐PRF also stimulated fibroblast wound closure and promoted the ability of fibroblasts to induce endothelial tube formation. L‐PRF‐induced gene expression changes in fibroblast were similar to those observed in early human and pig wounds.

Conclusions

This study provides new insights into the biological mechanism by which L‐PRF regulates key gingival fibroblast functions important in wound healing.
Efficacy and safety of metformin and sitagliptin‐based dual and triple therapy in elderly Chinese patients with type 2 diabetes: Subgroup analysis of STRATEGY study
Authors: Liu Xiangyang , Wang Li , Xing Ying , Engel Samuel S , Zeng Longyi , Yao Bin , Xu Wen , Chen Guojuan , Zhang Ye , Zhang Ruya , Liu Shu , Weng Jianping , Ji Qiuhe
Published: April 2020

Aims/Introduction

To assess the efficacy and safety of metformin/sitagliptin‐based dual/triple therapy in elderly Chinese patients with type 2 diabetes mellitus.

Materials and Methods

This subgroup analysis included individuals aged ≥65 years from the STRATEGY study, a two‐stage study in which type 2 diabetes mellitus patients with unsatisfactory glycemic control on metformin were first treated with the dual combination of metformin and sitagliptin for 16 weeks (n = 681), and then, if glycemic control had not been achieved, were treated with a third add‐on oral antihyperglycemic drug for another 24 weeks (n = 291). The efficacy end‐point was change in glycated hemoglobin (HbA1c) in each stage, and the safety end‐point was adverse events with a focus on hypoglycemia.

Results

At week 16, the change in HbA1c was −0.81% from baseline, and the percentages of patients who achieved HbA1c targets of <7% and <7.5% were 44.9 and 67.2%, respectively. After 24 weeks, a further average HbA1c reduction of −0.60% was observed with specific reductions of −0.70% with glimepiride, −0.63% with gliclazide, −0.51% with repaglinide and −0.45% with acarbose. The proportions of patients who achieved HbA1c targets of <7% and <7.5% were 65.4 and 81.3%, respectively, over the entire study. The rates of drug‐related adverse events and hypoglycemia were, respectively, 4.1 and 4.3% in the dual therapy stage, and 5.2% and 7.1% in the triple therapy stage, without occurrence of severe hypoglycemia.

Conclusions

In elderly Chinese type 2 diabetes mellitus patients, metformin/sitagliptin‐based dual and triple oral therapy can provide clinically meaningful glycemic control and is generally well tolerated with a low incidence of hypoglycemia.
Changes in oral processing parameters of three rice varieties
Authors: Liu Dong Xiao , Ren Xin , Asimi Sailimuhan , Peng Jie , Zhang Min
Published: April 2020

Mastication and saliva addition affects the formation of a bolus, directly playing a key role in people's eating enjoyment. However, the specific changes of oral physiological parameters and bolus moisture content in the oral processing of rice have not been studied in detail. Thus, in the present study, salivary flow rate, salivary secretion, chewing frequency, and bolus moisture content during oral processing of three rice varieties (japonica rice, indica rice, and glutinous rice) were fully investigated. The differences among different rice and changes among different oral processing stages (25%, 50%, 75%, and 100%) were analyzed. Results showed that the swallowing time of glutinous rice was significantly lower than that of japonica and indica rice (p < .05). However, there was no significant difference in the chewing frequency of the three rice varieties throughout the oral processing stages (1.59–1.66 Hz, p > .05). During oral processing, the salivary flow rates for the three kinds of rice decreased significantly (p < .05), from 37.72 ± 4.32 mg/s (0%–25% stage) to 19.83 ± 5.50 mg/s (75%–100% stage). The dry basis moisture content of the bolus increased significantly (p < .05), from 1.53 ± 0.08 (0%) to 1.96 ± 0.02 (100%). In the 75%–100% stage, the amount of saliva secretion for japonica rice was highest, followed by indica rice and glutinous rice (p < .05). At the point of swallowing (100% stage), the dry basis moisture content of all three rice‐bolus' was consistent (1.94–1.99, p > .05).
Incidence, prevalence and mortality of autoimmune hepatitis in England 1997‐2015. A population‐based cohort study
Authors: Grønbæk Lisbet , Otete Harmony , Ban Lu , Crooks Colin , Card Timothy , Jepsen Peter , West Joe
Published: April 2020

Background & Aims

There are few population‐based studies of the incidence and mortality of autoimmune hepatitis. The burden of the disease and how it has changed over time have not been fully explored. We conducted a population‐based cohort study on the incidence and mortality of autoimmune hepatitis in England, 1997‐2015.

Methods

From the Clinical Practice Research Datalink we included 882 patients diagnosed with autoimmune hepatitis in England, 1997‐2015. The patients were followed through 2015, and we calculated the sex‐ and age‐standardized incidence and prevalence of autoimmune hepatitis. We examined variation in incidence by sex, age, calendar year, geographical region and socioeconomic status, and incidence rate ratios were calculated with Poisson regression. We calculated all‐cause and cause‐specific mortality.

Results

The overall standardized incidence rate of autoimmune hepatitis was 2.08 (95% confidence interval 1.94‐2.22) per 100,000 population per year, higher in women, higher in older age and independent of region and socioeconomic status. From 1997 to 2015 the incidence doubled from 1.27 (95% confidence interval 0.51‐2.02) to 2.56 (95% confidence interval 1.79‐3.33) per 100,000 population per year. The 10‐year cumulative all‐cause mortality was 31.9% (95% confidence interval 27.6‐36.5), and the 10‐year cumulative liver‐related mortality, including hepatocellular carcinoma was ~10.5%.

Conclusions

This population‐based study showed that the incidence of autoimmune hepatitis doubled over an eighteen‐year period. The incidence was particularly high in older women and was similar across all regions of England and independent of socioeconomic status. Patients with autoimmune hepatitis had a high mortality.
Determinants of volume status in peritoneal dialysis: A longitudinal study
Authors: Jaques David A. , Davenport Andrew
Published: April 2020

Aim

In peritoneal dialysis (PD), fluid overload is frequent and associated with cardiac dysfunction and mortality. As it is considered a modifiable risk factor, we wished to describe clinical determinants of fluid overload in a longitudinal cohort of PD outpatients.

Methods

We consecutively included PD outpatients treated with continuous ambulatory PD (CAPD) or automated PD (APD) attending for their routine clinical visit at a single tertiary hospital. Extracellular water (ECW) to total body water (TBW) ratio was measured by multifrequency bioelectrical impedance. Peritoneal transport characteristics were measured with a standard peritoneal equilibration test. Patients had a second follow‐up visit with the same measurements. Univariable and multivariable mixed linear regression models were conducted with ECW/TBW as the dependent variable.

Results

A total of 155 patients were enrolled with a median follow‐up time of 12 months. Median dialysis vintage was 13.5 ± 3.4 months. Overall mean value of ECW/TBW was 39.3% ± 1.1. In multivariable analysis, factors positively associated with ECW/TBW were: Age (P < .001), diabetes (P = .002), and SBP (P = .028). Factors negatively associated with ECW/TBW were: nPNA (P = .001), serum albumin (P < .001) and PTH (P = .014). None of the considered variable showed a significant interaction with time.

Conclusion

We confirm a high prevalence of fluid overload in PD patients and show that it is strongly associated with older age, diabetes, hypoalbuminemia and protein energy wasting. In contrast, when PD prescription is tailored to patient's individual characteristics, residual renal function, PD modality and peritoneal characteristics are not decisive in controlling volume status.
Sella turcica morphometrics in children with unilateral cleft lip and palate
Authors: Antonarakis Gregory S. , Huanca Ghislanzoni Luis , La Scala Giorgio C. , Fisher David M.
Published: April 2020

Objective

To use morphometric methods to investigate the size and shape of the sella turcica in children with unilateral cleft lip and palate (UCLP).

Setting and sample population

Fifty‐six healthy children with non‐syndromic UCLP, from a major paediatric teaching hospital, with lateral cephalograms taken prior to alveolar bone grafting, were compared with an age‐ and sex‐matched control group of healthy children without orofacial clefts, with lateral cephalograms taken prior to orthodontic treatment.

Materials and methods

In this cross‐sectional study, conventional measurements were performed on the sella turcica to measure width, height and area on lateral cephalograms. Sella shape was also analysed using 11 points defining the sella turcica contours, using geometric morphometrics. Procrustes superimposition was used to register all sella contour tracings to calculate average sella shape. Principal component analysis was applied to the residuals of the point coordinates, and principal components (PCs) of shape were extracted.

Results

Statistically significant differences between the UCLP and control groups were found for sella posterior height, midpoint height, maximum height and area, where all of these were smaller in children with UCLP. Principal component analysis revealed that the first two PCs accounted for 84.7% of total shape variance. There was a statistically significant difference in sella shape between children with UCLP and control children.

Conclusions

In children with UCLP, the sella turcica is shorter and with a smaller surface area when compared to matched non‐cleft children. Moreover, sella turcica shape, when disregarding size, seems to differ to that of non‐cleft children.
Frailty and cognitive impairment are predictive of takotsubo syndrome following pacemaker implantation
Authors: Niewinski Piotr , Walczak Tomasz , Królicki Tomasz , Kudla Tobiasz , Jagielski Dariusz , Nowak Krzysztof , Josiak Krystian , Tubek Stanisław , Banasiak Waldemar , Ponikowski Piotr
Published: April 2020

Background

Pacemaker (PM) implantation may cause acute emotional distress leading to takotsubo syndrome (TTS). Frailty and cognitive impairment are known to influence outcomes after surgical procedures. It is unclear whether they may also predispose to TTS following PM implantation.

Methods

We identified nine cases (81 ± 6 years) of TTS following PM implantation that took place between 2013 and 2017 in one high volume implantation center. TTS was diagnosed based on typical echocardiographic appearance with resolution over time and (in cases where deemed necessary) normal coronary angiography. The TTS cases were compared with 30 consecutive cases of PM implantation (75 ± 9 years), which were not complicated by TTS (control group). Frailty was assessed using retrospective Risk Analysis Index (RAI‐A). Pacing parameters were analyzed during PM implantation and after 1 month.

Results

Cognitive impairment was more prevalent (67% vs 10%, P = .0005), and RAI‐A index was significantly higher in the TTS group compared to the control group (26 ± 13.7 vs 13.1 ± 9.8, P = .008). Perioperative right ventricular threshold was significantly higher in patients with TTS comparing to controls (0.99 ± 0.43 V vs 0.74 ± 0.20 V, P = .04). The magnitude of decrease in right ventricular threshold between implantation and 1 month follow‐up was greater in TTS patients compared to controls (−0.41 ± 0.29 V vs −0.15 ± 0.38 V, P = .049).

Conclusions

TTS is a rare complication of PM implantation. Patients with cognitive impairment and frailty are at risk of TTS. Right ventricular pacing threshold is acutely affected by TTS and improves over time.
Business model innovation in strategic alliances: a multi‐layer perspective
Authors: Spieth Patrick , Laudien Sven M. , Meissner Svenja
Published: April 2020

Business model innovation (BMI) has recently become a topic of interest for research as well as corporate practice. However, we lack specific insights into actors, drivers, and different forms of BMI as the concept is by now mainly addressed in a very general way. In this paper, we analyze how BMI takes place in strategic alliances with the focus of enhancing the recent knowledge about BMI by developing a concept that links firm‐level BMI with alliance‐driven innovation of business models. Against the background of an in‐depth explorative qualitative study, we shed light on the basic nature business model innovation alliances (BMIA) and their effects on both, alliance level and firm level. We develop a process model of BMIA that is the first model providing a holistic picture of this particular type of BMI. Our findings allow for deep insights into BMI processes in incumbent companies and uncover in detail the importance of boundary spanning activities in this realm. By providing these insights, we pave the ground for a new stream of BMI research that focuses on the in‐depth understanding of the role of collaboration and network effects in recent BMI processes. In addition, we show practical benefits for partners in BMI alliances. These insights may help to overcome the traditional fear of negative effects that is still very often prevalent in companies when it comes to issues of partnering with firm external players in strategic issues.
Novel HLA‐B*50:66 allele, identified by next‐generation sequencing in a Saudi individual
Authors: Jawdat Dunia , Almusa Abdullah , Alnafie Qamariyyah , Alaskar Ahmed S. , Hajeer Ali H.
Published: April 2020

HLA‐B*50:66 differs from HLA‐B*50:01:01:01 by a single nucleotide substitution (C>A) in codon 153.
Sensitive detection systems for infectious agents in xenotransplantation*
Authors: Denner Joachim
Published: April 2020

Xenotransplantation of pig cells, tissues, or organs may be associated with transmission of porcine microorganisms, first of all of viruses, to the transplant recipient, potentially inducing a disease (zoonosis). I would like to define detection systems as the complex of sample generation, sample preparation, sample origin, time of sampling, and the necessary negative and positive controls along with the specific detection methods, either PCR‐based, cell‐based, or immunological methods. Some xenotransplantation‐relevant viruses have already been defined; others are still unknown. The PCR‐based methods include PCR and real‐time PCR for DNA viruses, and RT‐PCR and real‐time RT‐PCR for RNA viruses as well as for virus expression studies at the RNA level. Furthermore, droplet digital PCR (ddPCR) can be used for the determination of virus and provirus copies. To detect expression at the protein level, immunofluorescence, immunohistochemistry, and Western blot analyses can be used. To detect virus production and to detect infectious viruses, electron microscopy and infection assays can be used. Furthermore, immunological methods such as Western blot analysis or ELISA can be used to detect virus‐specific antibodies. Detection of antiviral antibodies is a reliable and sensitive indirect detection method. For these immunological methods, purified viruses, recombinant viral proteins, or synthetic peptides are used as antigens and control sera and control antigens are needed. All these methods have been used in the past for the characterization of different pig breeds including genetically modified pigs generated for xenotransplantation and for the screening of recipients in preclinical and clinical xenotransplantations. Whereas in preclinical trials a few porcine viruses have been transmitted to the non‐human primate recipients, in first clinical trials no such transmissions to humans were observed. Further improvement of the detection systems and their application in virus elimination programs will lead to clean donor animals and a safe xenotransplantation.
Potential mutant of Lentinula edodes with high yield of (1-3), (1-6-), β-D-glucan
Authors: Mahmood Ibrahim , Mohamad Azhar , Daud Fauzi , Othman Babul Airianah , Law Douglas , Hoong Cheah Yew , Idris Mushrifah , Mat Lazim Azwan , Joe Lim Seng , Jamar Nur Hidayah , Eziwar Dyari Herryawan Ryadi , Sidik Nik Marzuki , Fazry Shazrul
Published: April 2020

Lentinula edodes or better known as Shiitake mushroom contains β-1,3;1,6-glucan as part of the cell wall components and studies have shown that it has the ability to enhance the immune system and work as anticancer. The aim of this study is to create potential strain of L. edodes with the high content of β-1,3;1,6-glucan, which has the potential for biotechnological purposes. L. edodes spores were irradiated with gamma ray (Ɣ-rays) and incubated, which formed monokaryon mycelium (MM). Compatible mating of mutated monokaryon formed mutant line dikaryon mycelium (MLDM) that were selected for genotypic and phenotypic comparison with the wild-type line dikaryon mycelium (WLDM). The concentration of β-1,3;1,6-glucan were measured using a commercial β-Glucan Megazyme Assay Kit (Yeast & Mushroom). Three MLDM, (A37, A26, and C07) 38.8, 36.0 and 34.5 %w/w of 100 mg respectively, significantly produced higher amount of β-1,3;1,6-glucan in comparison with WLDM (20.2 %w/w of 100 mg).
Impact of coastal development on mangrove distribution in Cherating Estuary, Pahang, Malaysia
Authors: Ahmad Zuhairi , Mohamad Suharni Muhammad Luqman , Taib Siti Noor Aifa , Shammodin Muhammad Shaheed
Published: April 2020

This study examined the impact of various coastal developments on mangrove cover along the Cherating Estuary, Pahang, Malaysia between 1997 and 2016. Series of Landsat imageries at Cherating Estuary have been analyzed using supervised classification. Over 19.99% (26.275 ha) of mangrove cover was degraded along the Cherating estuary from its total area of 131.642 ha during the past 20 years. The expansion of development or urban area can be observed in 1997 (27.93 ha) and in 2016 (111.02 ha), showing an increase by 297.0% in 20 years. We identified several causes of mangrove degradation, including mangrove clearing to commercial or residential area, and aquaculture activities. Cherating is one of the main tourism attractions in Pahang. The pace of coastal development throughout the estuary and the coast area had suppressed the mangroves propagation over the years. Long term monitoring of mangrove ecosystems is essential to ensure the survival and sustainability of mangrove associated biodiversity.
Wavelet-support vector machine for forecasting palm oil price
Authors: Shabri Ani , Abdul Hamid Mohd Fahmi
Published: April 2020

This study examines the feasibility of applying Wavelet-Support Vector Machine (W-SVM) model in forecasting palm oil price. The conjunction method wavelet-support vector machine (W-SVM) is obtained by the integration of discrete wavelet transform (DWT) method and support vector machine (SVM). In W-SVM model, wavelet transform is used to decompose data series into two parts; approximation series and details series. This decomposed series were then used as the input to the SVM model to forecast the palm oil price. This study also utilizes the application of partial correlation-based input variable selection as the preprocessing steps in determining the best input to the model. The performance of the W-SVM model was then compared with the classical SVM model and also artificial neural network (ANN) model. The empirical result shows that the addition of wavelet technique in W-SVM model enhances the forecasting performance of classical SVM and performs better than ANN.
The influence of sintering temperature on the crystal structure, electric and magnetic properties of Ba(2-X)Nd(X)Fe2O5 composite
Authors: Purwanto Patricius , Yunasfi Yunasfi , Mulyawan Ade
Published: April 2020

Magnetic composite material of Ba(2-x)Nd(x)Fe2O5 is used to make electromagnetic wave absorbers. The Ba(2-x)Nd(x)Fe2O5 (x = 0 and 0.1) system was synthesized by using solid state reaction method. The Ba(2-x)Nd(x)Fe2O5 system was made with mixture compound of BaCO3, Nd2O3 and Fe2O3 powders with a specific weight ratio, then continued to the milling process and heat treatment at different sintering temperatures. XRD (X-ray diffraction) was conducted for phase identification and to determination of the crystallite size and strain. The study on dielectric and magnetic properties was carried out by using LCR meter and VSM (vibrating sample magnetometer), respectively. The XRD results indicated that the main phase of Ba2Fe2O5 was best resulted at 1000 0C. Dielectric properties, such as AC conductivity and permittivity as a function of the frequency were studied for those best resulted samples. It is found that the substitution of Nd3+ enhances both of the AC conductivity and permittivity due to the changes of the charge carriers (so) and the hoping electron between Fe2+ and Fe3+ ions in the doped system. The M-H curves as the results of the magnetic measurement showed the sharp enhancement of the coercivity (Hc) and the slight reduction in the saturation magnetization (Ms) along with the substitution of the Nd3+.
The performance of CO2/N2 separation on P84/NCC-based tubular carbon membrane under different carbonization conditions
Authors: Sazali Norazlianie , Sharip Mohd Syafiq , Ibrahim Haziqatulhanis , Wan  Salleh Wan Norharyati , Mahyon Nur Izwanne , Kadirgama Kumaran , Harun Zawati , Sazali Norsuhailizah
Published: April 2020

In this study, the influence of carbonization environment on the performance of Tubular Carbon Membrane (TCMs) was explored. P84 co-polyimide/Nanocrystalline cellulose-based TCMs were synthesized by dip-coating technique. The permeation properties of TCMs were determined by employing pure gas of CO2 and N2. Heat treatment processes were carried out under different environment (Argon, Nitrogen, and Helium) with the flow rate of 200 ml/min to boost the membrane’s performance. The carbonization process was performed at a consistent carbonization temperature of 800oC under heating rate of 3oC/min. Carbonization under Argon environment was found to be the best condition for PI/NCC-based TCMs preparation with the permeance of 3.22±3.21and 213.56±2.17 GPU for N2, and CO2 gases, respectively. This membrane exhibited the uppermost CO2/N2 selectivity of 66.32±2.18. TCMs prepared under Ar environment experienced less weight loss while exhibiting highest CO2/N2 selectivity as compared to those prepared under He and N2 environment.
Morphological study of hydrophobic metakaolin hollow fibre membrane for membrane distillation application
Authors: Hubadillah Siti Khadijah , Othman Mohd Hafiz Dzarfan , Ismail Ahmad Fauzi , Rahman Mukhlis A. , Jaafar Juhana
Published: April 2020

Metakaolin hollow fibre membranes (MHFM) prepared by a combined phase inversion and sintering method were proposed for application in direct contact membrane distillation (DCMD). Four kinds of hydrophobic metakaolin hollow fibre membranes (h-MHFM) sintered at different temperatures (1200ºC to 1500ºC) were successfully prepared by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane on the MHFM. Prior to the grafting process, hydrolysis with a mixture of ethanol and water with ratio 1:2 was applied for 24 hours. The effectiveness of hydrophobization on each MHFM was assessed using contact angle measurement, scanning electron microscopy (SEM) and 3-point bending. It was found that increasing sintering temperature increased the mechanical strength from 117.6 MPa to 182.3 MPa. Further increment was observed when mofification with FAS was applied. After modification, the contact angle was enhanced up to 120º. In general, membrane prepared at lower sintering temperature of 1200°C exhibited higher DCMD performance with water vapor flux of 17.5 kg/m2h due to sufficient pore size for the vapor to pass through the memrbane structure. It was suugested that this membrane is suitable for any condition of water treatment including heavy metal removal, due to its excellent properties to act in harsh condition and best DCMD performance.
Predicting the performance of the players in NBA Players by divided regression analysis
Authors: Goh Yann Ling , Goh Yeh Huann , Raymond Ling Leh Bin , Chee Weng Hoong
Published: April 2020

A divided regression model is built to predict the performance of the players in the National Basketball Association (NBA) from year 1997 until year 2017. The whole data set is divided into five groups of sub data sets and multiple linear regression model is employed to model each of the sub data set. In addition, the relationships among independent variables are checked by using variance inflation factor (VIF) to identify the risk of having multicollinearity in the data. Moreover, non-linearity of regression model, non-constancy of error variance and non-normality of error terms are investigated by plotting residual plots and quantile-quantile plots. Finally, a divided regression model is built by combining the results obtained from the sub data sets and the performance of the divided regression model is verified.
Prediction of stress shielding around implant screws induced by three-point and four-point bending
Authors: Basirom Izzawati , Rojan Mohd Afendi , Abdul Majid Mohd Shukry , Md Zain Nor Alia , Bajuri Mohd Yazid
Published: April 2020

Implant screws failure commonly occurs due to the load that constantly generated by the patient’s body to the fracture area. Bending load is often encountered in femur bone due to lateral impact which affected the bone and also the implants installed. Consequently, the load will lead to the failure of implants that can cause loosening or tightening of implants. Henceforth, in this manner, it is significant to study the bending behavior of bone implant in femur bone. The aim of this study was to analyze the stress shielding of bone implant on the internal fixator. 3D technique is able to show the overall deformation and stress distribution. The lower the biomechanical compatibility, the lower the STP value obtained. In addition, the variation of elastic modulus (E) of the screws materials, 200GPa (Stainless Steel) and 113.8GPa (Titanium) resulted in the increase of the total stress transferred (STP) between screw and bone interface. In this work, strain energy density (SED) was determined as a good indicator of stress shielding.
Chlorogenic acid from banana and papaya peels inhibit lipid accumulation in 3T3-L1 cells
Authors: Mohamad Yazid Nurulain-Syuhada , Zulkifli Muhammad Faiz , Wan Ismail Wan Iryani , Siva Raseetha
Published: April 2020

The aim of this study was to determine the capability of chlorogenic acid (CGA) from banana (Saba) and papaya (Caricaceae) peels to inhibit lipid accumulation. Total phenolic content (TPC), CGA content, cytotoxic activity, and lipid profiling for both ethanolic and water extracts of both fruit peels at ripe (Sbr and Cpr) and unripe (Sbur and Cpur) stages were conducted. TPC for Sbr water extract (20.66 mg GAE/g DW) was significantly higher than that of the Sbr ethanolic extract (2.88 mg GAE/g DW). CGA was significantly higher in Cpr water extract (10.08 mg/L) compared to ethanolic extract (5.54 mg/L). Cytotoxic activity of the extract was determined by MTT assay using 3T3-L1 pre-adipocyte cell lines. Lipid study was assessed by Oil Red-O staining and adipolysis assay. All of the extracts showed no cytotoxic effect towards the adipocyte cells. The extracts significantly reduced lipid accumulation and had higher adipolysis rate compare to control, indicating the reduction in lipid production in 3T3-L1 adipocyte cell lines.(Abbreviations: Sbr: Saba banana ripe; Sbur: Saba banana unripe; Cpr: Caricaceae papaya ripe; Cpur: Caricaceae papaya unripe.)
GPTMS-Montmorillonite-filled biopolymer chitosan membrane with improved compatibility, physicochemical, and thermal stability properties ochemical and thermal stability properties
Authors: Atmaja Lukman , Purwanto Mochammad , Salleh Muhammad Taufiq , Mohamed Mohamad Azuwa , Jaafar Juhana , Ismail Ahmad Fauzi , Santoso Mardi , Widiastuti Nurul
Published: April 2020

The chitosan/organo-montmorillonite (Ch/O-MMT) membrane was fabricated and tested. Surface modification of O-MMT particles using 3-glicydoxy propyl trimethoxysilane (GPTMS) to enhance its compatibility with chitosan is presented. The resulting composite membrane was characterized by using SEM, AFM, and FTIR to observe the morphological and functional group structure. The crystallinity, thermal stability, and mechanical strength was analyzed by XRD, TGA, and tensile test. The results suggested that the modification of MMT using GPTMS could increase the compatibility of O-MMT with chitosan membrane, thus producing a good composite membrane with well-dispersed MMT filler within the chitosan polymer matrices. Based on the FTIR analysis, the presence of GPTMS could improve the interaction between chitosan and O-MMT material, thus forming more hydrogen bonding with chitosan membrane than Ch/MMT membrane. The TGA curve analysis showed that the addition of inorganic filler into chitosan organic matrices was able to increase the thermal stability of Ch/MMT and Ch/O-MMT composite membrane, suggested to mechanical strength analysis. The improvement in thermal stability was due to the absence of hydrogen bonding formations between chitosan polymer and O-MMT filler. In addition, greater hydrogen bonding formation would lead to the tighter packing of Ch/O-MMT composite membrane, resulting in higher bonding strength and higher thermal resistance. All of the characterization results conﬁrmed that the Ch/O-MMT composite membrane has better physicochemical properties than Ch/MMT composite membrane.
Potential of Leucas zeylanica extract to eliminate E. coli and S. aureus in Corbicula fluminea (“Etak”) tissue
Authors: Abdullah Faizuan , Md. Nasir Siti Nor Aini , Han Dee Koh , Appalasamy Suganthi , Mohamad Nor Maryana , Rak Aweng Eh
Published: April 2020

“Etak” or Corbicula fluminea, is a freshwater mollusc species regularly consumed as a popular snack among the Kelantanese in Malaysia. The “etak” is usually heated with traditional smoking process which is considered as half cooked and the smoked C. fluminea is commonly known as “etak salai”. This study focuses on the potential of Leucas zeylanica leaves extract to eliminate the bacteria content in “etak salai”. Extraction of bacterial genomic DNA was performed and confirmed the existence of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in “etak salai”. Antibacterial properties of L. zeylanica leaves extract was identified using disc diffusion assay and the result obtained exhibit that 70 μg/μL of L. zeylanica extract was the optimum concentration to give the effect of 11 mm inhibition zone for E. coli and 15 mm inhibition zone for S. aureus. This finding proof that L. zeylanica leaves could be the ingredients in the paste for “etak salai” preparation.
Viscous dissipation and chemical reaction effects on MHD Casson nanofluid over a stretching sheet
Authors: Govardhan Kamatam , Narender Ganji , Sreedhar Sarma Gobburu
Published: April 2020

A numerical analysis was performed for the mathematical model of boundary layer flow of Casson nanofluids. Heat and mass transfer were analyzed for an incompressible electrically conducting fluid with viscous dissipations and chemical reaction past a stretching sheet. An appropriate set of similarity transformations were used to transform the governing partial differential equations (PDEs) into a system of nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is solved numerically by using shooting method. A detailed discussion on the effects of various physical parameters and heat transfer characteristics was also included.
A Gait Trajectory Control Scheme Through Successive Approximation Based on Radial Basis Function Neural Networks for the Lower Limb Exoskeleton Robot
Authors: Ren Bin , Luo Xurong , Wang Yao , Chen Jiayu
Published: April 2020

Stability control is critical to the exoskeleton robot controller design. Considering the complex structural characteristics of lower limb exoskeleton robots, the major challenge of the controller design is the accuracy and uncertainty of the dynamics model. To fill in this research gap, this study proposes successive approximation-based radial basis function (RBF) neural networks (NNs). The proposed model simplifies the lower limb exoskeleton robot as three degrees-of-freedom (3-DOF) model with the human hip joints for adduction/extension, bending/extension, and internal/external rotation. To minimize the gait tracking errors and stabilize the closed-loop system, a gait trajectory-based control and approximation model was proposed in this study. To verify the proposed method, a validation experiment was conducted for typical lower limb motions. The experiment results demonstrated the effectiveness of the proposed method.
A Gaussian Process-Based Crack Pattern Modeling Approach for Battery Anode Materials Design
Authors: Zheng Zhuoyuan , Chen Bo , Xu Yanwen , Fritz Nathan , Gurumukhi Yashraj , Cook John , Ates Mehmet N. , Miljkovic Nenad , Braun Paul V. , Wang Pingfeng
Published: April 2020

Silicon-based anodes are one of the promising candidates for the next generation high-power/energy density lithium ion batteries (LIBs). However, a major drawback limiting the practical application of the Si anode is that Si experiences a significant volume change during lithiation/delithiation, which induces high stresses causing degradation and pulverization of the anode. This study focuses on crack initiation within a Si anode during the delithiation process. A multi-physics-based finite element (FE) model is built to simulate the electrochemical process and crack generation during delithiation. On top of that, a Gaussian process (GP)-based surrogate model is developed to assist the exploration of the crack patterns within the anode design space. It is found that the thickness of the Si coating layer, TSi, the yield strength of the Si material, σFc, the cohesive strength between Si and the substrate, σFs, and the curvature of the substrate, ρ, have large impacts on the cracking behavior of Si. This coupled FE simulation-GP surrogate model framework is also applicable to other types of LIB electrodes and provides fundamental insights as building blocks to investigate more complex internal geometries.
Energy Harvesting Performance of Vertically Staggered Rectangle-Through-Holes Cantilever in Piezoelectric Vibration Energy Harvester
Authors: Gao Shan , Ao Hongrui , Jiang Hongyuan
Published: April 2020

Piezoelectric vibration energy harvesting technology has attracted significant attention for its applications in integrated circuits, microelectronic devices, and wireless sensors due to high power density, easy integration, simple configuration, and other outstanding features. Among piezoelectric vibration energy harvesting structures, the cantilevered beam is one of the simplest and most commonly used structures. In this work, a vertically staggered rectangle-through-holes (VS-RTH) cantilevered model is proposed, which focuses on the multi-directional vibration collection. To verify the output performance of the device, this paper employs basic materials and fabrication methods with mathematical modeling. The simulations are conducted through finite element methods to discuss the properties of VS-RTH energy harvester on resonant frequency and output characteristics. Besides, an energy storage circuit is adopted as a collection system. It can achieve a maximum voltage of 4.5 V which is responded to the harmonic vibrating input of 1 N force and 1 m/s2 in a single vibrating direction. Moreover, the power density is 2.596 W/cm3 with a 100 kΩ resistor. It is almost four times better than the output of unidirectional cantilever beam with similar resonant frequency and volume. According to the more functionality in the applications, VS-RTH energy harvester can be used in general vibration acquisition of machines and vehicles. Except for electricity storage, the harvester can potentially employ as a sensor to monitor the diversified physical signals for smooth operation and emergence reports. Looking forward, the VS-RTH harvester renders an effective approach toward decomposing the vibration directions in the environment for further complicating vibration applications.
Structural Changes of TiO2 as a Result of Irradiation by E-Beam and X-Rays
Authors: Paunović Perica , Grozdanov Anita , Makreski Petre , Gentile Gennaro
Published: April 2020

The subject of this research was to monitor and evaluate the effect of X-rays and e-beam irradiation on the structure of nanoscaled TiO2 and its properties. The samples of nanoscaled TiO2 were synthesized using the sol–gel method and subsequently exposed to thermal treatment to obtain the anatase crystalline structure. X-ray powder diffraction (XRPD) and Raman spectroscopy revealed the following changes in the structure as a result of the e-beam and X-ray irradiation: a decrease in the size of the crystallite of TiO2, an increase of the distance between the crystalline planes and the lattice parameters as well as the achievement of a certain degree of amorphization. As a consequence of the structural changes, thermal stability decreased. Also, a shift of the light absorption toward the visible end of the spectrum was detected and the energy of the band gap was reduced, indicating a better photocatalytic activity, i.e., the photocatalytic action can be shifted to the region of the visible light.
Parametric Study and Uncertainty Quantification of the Nonlinear Modal Properties of Frictional Dampers
Authors: Sun Yekai , Yuan Jie , Pesaresi Luca , Denimal Enora , Salles Loïc
Published: April 2020

A numerical methodology is described to study the influence of the contact location and contact condition of friction damper in aircraft engines. A simplified beam model is used to represent the blade for the preliminary design stage. The frictional damper is numerically analyzed based on two parameters, contact angle and vertical position of the platform. The nonlinear modal analysis is used to investigate the nonlinear dynamic behavior and damping performances of the system. The harmonic balanced method with the continuation technique is used to compute the nonlinear modes for a large range of energy levels. By using such a modeling strategy, the modal damping ratio, resonant amplitude, and resonant frequency are directly and efficiently computed for a range of design parameters. Monte Carlo simulations together with Latin hypercube sampling is then used to assess the robustness of the frictional damper, whose contact parameters involve much uncertainties due to manufacturing tolerance and also wear effects. The influences of those two parameters are obtained, and the best performances of the frictional damper can be achieved when the contact angle is around 25 deg–30 deg. The vertical position of the platform is highly mode dependent, and other design considerations need to be accounted. The results have proved that the uncertainties that involved contact surfaces do not have significant effects on the performance of frictional damper.
The Effect of Surface Finish on the Proper Functioning of Underplatform Dampers
Authors: Gastaldi Chiara , Berruti Teresa M. , Gola Muzio M.
Published: April 2020

Underplatform dampers are used to limit the resonant vibration of turbine blades. In recent years, various strategies have been implemented to maximize their damping capability. Curved-flat dampers are preferred to ensure a predictable bilateral contact, while a pre-optimization procedure was developed to exclude all those cross-sectional shapes that will bring the damper to roll and thus limit the amount of dissipated energy. The pre-optimization bases its predictions on the assumption that the effective width of the flat contact interface corresponds to the nominal one. It is shown here that this hypothesis cannot be relied upon: the energy dissipated by two nominally identical dampers, machined according to the usual industrial standards, may differ by a factor up to three due to the morphology of the flat-to-flat contact interface. Five dampers have been tested on two dedicated test rigs, available in the AERMEC laboratory, specially designed to reveal the details of the damper behavior during operation. Their contact interfaces are scanned by means of a profilometer. In each case, the mechanics, the kinematics, and the effectiveness of the dampers in terms of cycle shape and dissipated energy are correlated to the morphology of the specific contact surface. To complete the picture, a state-of-the-art numerical simulation tool is used to show how this tribo-mechanic phenomenon, in turn, influences the damper effect on the dynamic response of the turbine.
Implementation and Comparison of Contact Models Within PIRAT for Nuclear Reactivity Control Systems
Authors: Bonney Matthew S. , Zabiégo Maxime
Published: April 2020

The reactivity control system is a vital safety system for a nuclear reactor. One of the most challenging aspects in the design of these systems is the operation during critical situations, in particular during earthquakes to safely shut-down the reactor. To study these situations, the toolbox python Implementation for Reliability Assessment Tools (PIRAT) is used to model two types of excitation: single frequency and realistic. The main focus of this work is the comparison of the implementation of the contact models used to describe the interaction between the subsystems. For the dynamic tool in PIRAT (dynamic Euler–Bernoulli for seismic event (DEBSE)), this is done with a two-stage linear spring or Lankarani and Nikravesh-based models. For the sine excitation, the results show four distinct response types with the maximum displacement varying between the models. Low-frequency excitation showed little variance while higher frequency excitation showed large variations. The realistic excitation, however, did not show these variations and showed nearly identical results for the contact models tested. This gives confidence in the simulations since the user selected contact model did not greatly affect the simulation results for a realistic excitation.