bluuebunny/crossref_metadata_2025 huggingface dataset:
Key Schedule against Template Attack-Based Simple Power Analysis on a Single Target
Authors: Won Yoo-Seung , Sim Bo-Yeon , Park Jong-Yeon
Published: June 2020

Since 2002, there have been active discussions on template attacks due to the robust performance of such attacks. There are reports of numerous proposals to improve the accuracy of prediction model in order to identify the point of interest. To date, many researchers have only focused on the performance of template attacks. In this paper, we introduce a new approach to retrieve the secret information in key schedules, without the profiling phase utilizing secret information. The template attack allows us to reveal the correct key even though the encryption/decryption processes have powerful countermeasures. More precisely, if the templates are sufficiently built in loading/saving the public information, in the extraction phase, the templates already created can be applied to the identical operation about secret information, which allows us to retrieve the secret information even if the countermeasures are theoretically robust. This suggestion becomes another backdoor to avoid hardened countermeasures. In order to demonstrate our proposal, we consider the Advanced Encryption Standard key schedule as a target for attack; however, it cannot be the target of non-profiling attacks in general. Finally, the Hamming weight information of the correct key could be recovered in an XMEGA128 chip, without the secret information. Moreover, we concentrate on the potential possibility of our suggestion since the performance cannot outperform the original methods used in such attacks.
Lesch-Nyhan Syndrome: Evaluation of a Modified Bite Device to Prevent Bite Injuries
Authors: Ierardo Gaetano , Luzzi Valeria , Sfasciotti Gian Luca , Polimeni Antonella , Bossù Maurizio
Published: June 2020

Lesch-Nyhan syndrome (LNS) is a serious form of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency, a hereditary purine metabolism disorder. The prevalence reported in the literature is 1/380,000 to 235,000 births. Males are affected and females are heterozygous carriers. LNS patients present a combination of hypotonia, spasticity, and neurological and behavioral disorders. They also show an obsessive-compulsive self-injurious behavior with bites and injuries to the lips, tongue, cheeks and fingers. The literature offers little scientific contribution related to the management of this problem. The authors describe their experience with a 4-year-old LNS patient and present a viable solution to control and avoid bite injuries, namely a specifically modified bite. The patient was treated at the Pediatric Dentistry Department of “Sapienza” University of Rome with a modified bite with the internal surface, in contact with the teeth, realized in 2-mm-thick soft silicone, and the exterior part consisting of a transparent resin shell with front and rear shields to separate lips and cheeks from the dental arches. At a 12-month follow-up visit, compliance was excellent: the child wore the device with regularity and without discomfort, even during soft-food feeding. No intraoral bite injuries were found, with a general improvement of the young patient’s quality of life.
From the Extraction of Currently Fulfilled Requirements to Value Curves: A Case Study in the Field of Harvesting Machines for Shell Fruits and Lessons Learnt in Engineering Design
Authors: Maccioni Lorenzo , Bietresato Marco , Borgianni Yuri
Published: June 2020

The market for agricultural machinery is characterized by products with a high degree of maturity in the product life cycle. Consequently, current improvements in new machinery are predominantly incremental and new projects basically use solutions that are already consolidated. This makes this domain appropriate for benchmarking existing systems and envisioning new value propositions. The present paper deals primarily with the former and uses the value curves as a means to structure the comparison among different families of technical systems; in particular, harvesting machines for shell fruits from the ground surface, e.g., chestnuts, walnuts, and hazelnuts, were investigated here. The process of building value curves requires the identification of currently fulfilled requirements. Despite the attention paid by engineering design research to requirements, a structured process is lacking to extract relevant information and create value curves or other representations useful for benchmarking. The present paper approaches this problem and presents how the authors have individuated relevant knowledge for characterizing different categories of harvesting machines. Namely, after an extensive search of the scientific literature and patents, a critical review of existing machines, aimed at individuating their functioning principles, architecture, and attitude in fulfilling specific design requirements, was performed. Then, existing machines were classified in 8 main categories, and their strengths and weaknesses were identified with reference to 11 competing factors. The consequent construction of value curves enabled the identification of possible points of intervention by hypothesizing possible future evolutions of such machinery, both in a structural and in a value-based perspective. Limitations about the repeatability of the followed approach and possible repercussions on design research are discussed.
Deep Learning-Based Image Classification through a Multimode Fiber in the Presence of Wavelength Drift
Authors: Kakkava Eirini , Borhani Navid , Rahmani Babak , Teğin Uğur , Moser Christophe , Psaltis Demetri
Published: June 2020

Deep neural networks (DNNs) are employed to recover information after its propagation through a multimode fiber (MMF) in the presence of wavelength drift. The intensity distribution of the speckle patterns generated at the output of an MMF when an input wavefront propagates along its length is highly sensitive to wavelength changes. We use a tunable laser to implement a wavelength drift with a controlled bandwidth, aiming to estimate the DNN’s performance in different cases and identify the limitations. We find that when the DNNs are trained with a dataset which includes the noise induced by wavelength changes, successful classification of a speckle pattern can be performed even for a large wavelength bandwidth drift. A single training step is found to be sufficient for high classification accuracy, removing the need for time-consuming recalibration at each wavelength.
Neighborhood Aggregation Collaborative Filtering Based on Knowledge Graph
Authors: Zhang Dehai , Liu Linan , Wei Qi , Yang Yun , Yang Po , Liu Qing
Published: June 2020

In recent years, the research of combining a knowledge graph with recommendation systems has caused widespread concern. By studying the interconnections in knowledge graphs, potential connections between users and items can be discovered, which provides abundant and complementary information for recommendation of items. However, most existing studies have not effectively established the relation between entities and users. Therefore, the recommendation results may be affected by some unrelated entities. In this paper, we propose a neighborhood aggregation collaborative filtering (NACF) based on knowledge graph. It uses the knowledge graph to spread and extract the user’s potential interest, and iteratively injects them into the user features with attentional deviation. We conducted a large number of experiments on three public datasets; we verifyied that NACF is ahead of the most advanced models in top-k recommendation and click-through rate (CTR) prediction.
Cu Nano-Roses Self-Assembly from Allium cepa, L., Pyrolysis by Green Synthesis of C Nanostructures
Authors: De Padova Paola , Generosi Amanda , Paci Barbara , Olivieri Bruno , Ottaviani Carlo , Quaresima Claudio , Suber Lorenza , Di Pietrantonio Fabio , Della Ventura Giancarlo , Pilloni Luciano , Supriya S , Hegde Gurumurthy
Published: June 2020

Carbon nanostructures are achieved by bio-waste Allium cepa, L., (onion vulgaris) peels through pyrolysis at 900 °C. They contain dispersed elements derived by their bio-precursors, like Mg, Ca, S, Na, K, and Cu. Here, we report the self-assembly of new Cu flower-shaped nanostructures organized as nano-roses. Remarkably, the nano-roses show rolled-up petals of Cu0 with a high chemical stability in air, exhibiting an intrinsic pure Cu crystalline phase. This suggests the exceptional potentiality to synthesize Cu0 nanostructures with novel physical/chemical properties. The size, morphology, and chemical composition were obtained by a combination of high-resolution scanning electron microscopy, energy dispersive X-ray spectroscopy, energy dispersive X-ray diffraction, and Raman spectroscopy.
Gold Nanoparticles for Drug Delivery and Cancer Therapy
Authors: Siddique Sarkar , Chow James C. L.
Published: June 2020

Nanomaterials are popularly used in drug delivery, disease diagnosis and therapy. Among a number of functionalized nanomaterials such as carbon nanotubes, peptide nanostructures, liposomes and polymers, gold nanoparticles (Au NPs) make excellent drug and anticancer agent carriers in biomedical and cancer therapy application. Recent advances of synthetic technique improved the surface coating of Au NPs with accurate control of particle size, shape and surface chemistry. These make the gold nanomaterials a much easier and safer cancer agent and drug to be applied to the patient’s tumor. Although many studies on Au NPs have been published, more results are in the pipeline due to the rapid development of nanotechnology. The purpose of this review is to assess how the novel nanomaterials fabricated by Au NPs can impact biomedical applications such as drug delivery and cancer therapy. Moreover, this review explores the viability, property and cytotoxicity of various Au NPs.
Numerical Evaluation of Rotordynamic Coefficients for Compliant Foil Gas Seal
Authors: Wang Xueliang , Liu Meihong , Kao-Walter Sharon , Hu Xiangping
Published: June 2020

Compliant foil gas seal is one of the advanced cylindrical gas seal technologies and can be commonly used in the secondary flow system of an aero-engine. It can enhance the dynamic stability of the aero-engine by meeting the steady requirements of the aero-engine seal system. To evaluate the performance of compliant foil gas seal, the steady performance of the gas seal is firstly analyzed to predict the sealing efficiency and obtain the pressure distribution of the gas seal in the compressible flow field. Then, the effects of the operating parameters on the rotordynamic coefficients are analyzed using the finite differential method. It can be used to predict the operation performance of the aero-engine and prepare for the optimization and test rig of compliant foil gas seal on the T-shaped groove.
Two-Stage Mask-RCNN Approach for Detecting and Segmenting the Optic Nerve Head, Optic Disc, and Optic Cup in Fundus Images
Authors: Almubarak Haidar , Bazi Yakoub , Alajlan Naif
Published: June 2020

In this paper, we propose a method for localizing the optic nerve head and segmenting the optic disc/cup in retinal fundus images. The approach is based on a simple two-stage Mask-RCNN compared to sophisticated methods that represent the state-of-the-art in the literature. In the first stage, we detect and crop around the optic nerve head then feed the cropped image as input for the second stage. The second stage network is trained using a weighted loss to produce the final segmentation. To further improve the detection in the first stage, we propose a new fine-tuning strategy by combining the cropping output of the first stage with the original training image to train a new detection network using different scales for the region proposal network anchors. We evaluate the method on Retinal Fundus Images for Glaucoma Analysis (REFUGE), Magrabi, and MESSIDOR datasets. We used the REFUGE training subset to train the models in the proposed method. Our method achieved 0.0430 mean absolute error in the vertical cup-to-disc ratio (MAE vCDR) on the REFUGE test set compared to 0.0414 obtained using complex and multiple ensemble networks methods. The models trained with the proposed method transfer well to datasets outside REFUGE, achieving a MAE vCDR of 0.0785 and 0.077 on MESSIDOR and Magrabi datasets, respectively, without being retrained. In terms of detection accuracy, the proposed new fine-tuning strategy improved the detection rate from 96.7% to 98.04% on MESSIDOR and from 93.6% to 100% on Magrabi datasets compared to the reported detection rates in the literature.
Multi-Channel Feature Pyramid Networks for Prostate Segmentation, Based on Transrectal Ultrasound Imaging
Authors: Geng Lei , Li Simu , Xiao Zhitao , Zhang Fang
Published: June 2020

Accurate segmentation for transrectal ultrasound imaging (TRUS) is often a challenging medical image processing task. The problem of weak boundary between adjacent prostate tissue and non-prostate tissue, and high similarity between artifact area and prostate area has always been the difficulty of TRUS image segmentation. In this paper, we construct a multi-channel feature pyramid network (MFPN) based on deep convolutional neural network-based prostate segmentation method to process multi-scale feature maps. Each level enhances the edge characteristics of the prostate by controlling the scale of the channel. The optimized regression mechanism of the target area was used to accurately locate the prostate. Experimental results showed that the proposed method achieved the key indicator Dice similarity coefficient and average absolute distance of 0.9651 mm and 0.504 mm, which outperformed state-of-the-art approaches.
Extended Depth-of-Field of a Miniature Optical Endoscope Using Wavefront Coding
Authors: Yang Lei , Chen Meng , Wang Jin , Zhu Meng , Yang Tong , Zhu Shimin , Xie Hongbo
Published: June 2020

Endoscopic imaging is an indispensable tool for visual inspection of surfaces in hard-to-access places. The conventional optical endoscope only enables imaging the regions that lie close to the focal plane, and therefore improving the depth of field (DOF) of an endoscopic system has recently attracted much attention. Here, we propose and demonstrate a simple, cost-effective, and easily available industrial endoscopic system, which is composed of a rigid tube and group of optical lenses. The outer diameter of the designed endoscopic modality presented in this article is 3 mm. By employing the wavefront coding technique, the DOF of newly-designed endoscope was extended to 2.7 mm in the proof-of-concept experiment, which is an increase of almost 10 times compared to the initial counterpart.
Datasets for Cognitive Load Inference Using Wearable Sensors and Psychological Traits
Authors: Gjoreski Martin , Kolenik Tine , Knez Timotej , Luštrek Mitja , Gams Matjaž , Gjoreski Hristijan , Pejović Veljko
Published: June 2020

This study introduces two datasets for multimodal research on cognitive load inference and personality traits. Different to other datasets in Affective Computing, which disregard participants’ personality traits or focus only on emotions, stress, or cognitive load from one specific task, the participants in our experiments performed seven different tasks in total. In the first dataset, 23 participants played a varying difficulty (easy, medium, and hard) game on a smartphone. In the second dataset, 23 participants performed six psychological tasks on a PC, again with varying difficulty. In both experiments, the participants filled personality trait questionnaires and marked their perceived cognitive load using NASA-TLX after each task. Additionally, the participants’ physiological response was recorded using a wrist device measuring heart rate, beat-to-beat intervals, galvanic skin response, skin temperature, and three-axis acceleration. The datasets allow multimodal study of physiological responses of individuals in relation to their personality and cognitive load. Various analyses of relationships between personality traits, subjective cognitive load (i.e., NASA-TLX), and objective cognitive load (i.e., task difficulty) are presented. Additionally, baseline machine learning models for recognizing task difficulty are presented, including a multitask learning (MTL) neural network that outperforms single-task neural network by simultaneously learning from the two datasets. The datasets are publicly available to advance the field of cognitive load inference using commercially available devices.
A Simplified Calculation Method of Seepage Flux for Slope-Wall Rock-Fill Dams with a Horizontal Blanket
Authors: Li Gehang , Shen Zhenzhong , Yang Chao
Published: June 2020

Seepage flux is very important in many hydraulic projects such as in the upper reservoir of a pumped storage power station because of its effect on economic benefits. However, upper reservoirs with a relatively high altitude are generally located above the groundwater level; thus, their leakage is difficult to estimate accurately. Here, using steady seepage theory and Darcy’s law, we propose a simplified calculation method to estimate the leakage of slope-wall rock-fill dams with a horizontal blanket. Using a one-dimensional governing equation for unsaturated seepage flows with the assumption of porous continuous media, formulas are derived for calculating the seepage flux of the dam in a steady state with different groundwater levels, which are mainly divided into two situations: those that are lower or higher than the bottom of the horizontal blanket. Then, two engineering examples are developed to assess the proposed method; the relative errors between the analytical results and numerical results are less than 10%. The results obtained from other analytical methods introduced by other researchers are also compared with our numerical results. The comparison results show that the proposed method is reliable and can be used for the estimation of reservoir leakage in situations where rapid results are needed, such as benefit assessments and safety evaluations.
Novel Fault Injection Attack without Artificial Trigger
Authors: Lim HanSeop , Lee JongHyeok , Han Dong-Guk
Published: June 2020

Theoretical process of fault injection attacks is defined as a process of recovering a secret key assuming that an attacker can inject faults into a specific targeted operation. Therefore, an artificial triggering is required to execute such an attack. However, when conducting analysis on real devices, artificial triggering needs to rely on a powerful assumption, such as manipulation of internal codes. In this paper, we propose a novel fault injection system using Input/Output (I/O) signals of target devices as a trigger for relaxing an attacker assumption. This system does not require an implementation of artificial triggering as input signals are used as a trigger in transmission of plaintexts for fault injection attacks. As a result, the attacker can perform fault injection attacks concerning the entire encryption process. To decide the fault injection time based on the trigger, the proposed system applies simple power analysis (SPA), employing electromagnetic emission of target devices. Considering that the fault injection time identified by SPA can be relatively vague compared with that obtained using a system based on an artificial triggering, we address this problem by proposing a process to recover the secret key without knowing the byte index of an injected fault.
The Impact of Kelvin Wave Activity during Dry and Wet African Summer Rainfall Years
Authors: Mekonnen Ademe , Schreck Carl J. , Enyew Bantwale D.
Published: June 2020

This study highlights the influence of convectively coupled Kelvin wave (KW) activity on deep convection and African easterly waves (AEWs) over North Africa during dry and wet boreal summer rainfall years. Composite analysis based on 25 years of rainfall, satellite observed cold cloud temperature, and reanalysis data sets show that KWs are more frequent and stronger in dry Central African years compared with wet years. Deep convection associated with KWs is slightly more amplified in dry years compared with wet years. Further, KW activity over North Africa strengthens the lower level zonal flow and deepens the zonal moisture flux in dry years compared with wet years. Results also show that enhanced KW convection is in phase with above-average AEW variance in dry years. However, enhanced KW convection is out-of-phase with average AEW activity in wet years. In general, this study suggests that KW passage over Africa enhances convective activity and more strongly modulates the monsoon flow and moisture flux during the dry years than wet years.
Correction: Stalder, et al.; Value of SUVmax for the Prediction of Bone Invasion in Oral Squamous Cell Carcinoma. Biology 2020, 9, 23
Authors: Stalder Stephanie A. , Schumann Paul , Lanzer Martin , Hüllner Martin W. , Rupp Niels J. , Broglie Martina A. , Morand Grégoire B.
Published: June 2020

The authors would like to make a correction to their published paper [...]
Anti-Anaphylactic Activity of Isoquercitrin (Quercetin-3-O-β-d-Glucose) in the Cardiovascular System of Animals
Authors: Park Jinbong
Published: June 2020

Effects of isoquercitrin (IQ) on anaphylactic responses were examined in cardiovascular systems of experimental animals. In pithed rats, IQ at 30 and 100 mg/kg (intravenous) significantly blunted both the initial hypertensive and the ensuing hypotensive responses during anaphylaxis. Death rate and tachycardia were also significantly inhibited after the same IQ doses in these rats. In isolated guinea pig hearts, IQ infusion at 30–100 μg/mL markedly reduced anaphylaxis-related coronary flow decrease, contractile force change, and heart rate responses (both tachycardia and arrhythmia). Cardiac histamine and creatine kinase releases were similarly diminished by IQ during anaphylaxis in the isolated guinea pig hearts. In two different isolated guinea pig vasculatures, the pulmonary artery and mesenteric arterial bed, anaphylactic vasoconstriction was reduced by IQ 30 and 100 μg/mL. It was observed that IQ had a marked inhibitory effect on histamine release from rat mast cells, and this mechanism was suggested as the major anti-anaphylactic mechanism. Direct inhibition of histamine-induced muscle contraction did not seem to be relevant, but IQ treatment successfully repressed intracellular calcium influx/depletion in mast cells. Overall, this study provided evidence for the beneficial effect of IQ on cardiac anaphylaxis, thus suggesting its potential applications in the treatment and prevention of related diseases.
Higher Epoxyeicosatrienoic Acids in Cardiomyocytes-Specific CYP2J2 Transgenic Mice Are Associated with Improved Myocardial Remodeling
Authors: Aliwarga Theresa , Guo Xiaoyun , Evangelista Eric A. , Lemaitre Rozenn N. , Sotoodehnia Nona , Gharib Sina A. , Zeldin Darryl C. , Liu Qinghang , Totah Rheem A.
Published: June 2020

Elevated cis-epoxyeicosatrienoic acids (EETs) are known to be cardioprotective during ischemia-reperfusion injury in cardiomyocyte-specific overexpressing cytochrome P450 2J2 (CYP2J2) transgenic (Tr) mice. Using the same Tr mice, we measured changes in cardiac and erythrocyte membranes EETs following myocardial infarction (MI) to determine if they can serve as reporters for cardiac events. Cardiac function was also assessed in Tr vs. wild-type (WT) mice in correlation with EET changes two weeks following MI. Tr mice (N = 25, 16 female, nine male) had significantly higher cardiac cis- and trans-EETs compared to their WT counterparts (N = 25, 18 female, seven male). Total cardiac cis-EETs in Tr mice were positively correlated with total cis-EETs in erythrocyte membrane, but there was no correlation with trans-EETs or in WT mice. Following MI, cis- and trans-EETs were elevated in the erythrocyte membrane and cardiac tissue in Tr mice, accounting for the improved cardiac outcomes observed. Tr mice showed significantly better myocardial remodeling following MI, evidenced by higher % fractional shortening, smaller infarct size, lower reactive oxygen species (ROS) formation, reduced fibrosis and apoptosis, and lower pulmonary edema. A positive correlation between total cardiac cis-EETs and total erythrocyte membrane cis-EETs in a Tr mouse model suggests that erythrocyte cis-EETs may be used as predictive markers for cardiac events. All cis-EET regioisomers displayed similar trends following acute MI; however, the magnitude of change for each regioisomer was markedly different, warranting measurement of each individually.
Comparative Study Involving Effect of Curing Regime on Elastic Modulus of Geopolymer Concrete
Authors: Azarsa Peiman , Gupta Rishi
Published: June 2020

Geopolymer Concrete (GPC) as a cement-less construction material has attracted worldwide attention due to its lower carbon footprint. There are numerous studies reported on GPC made using different by-products including fly-ash. However, since the use of bottom-ash is comparatively limited, making potassium-based GPC using this waste can be an alternative to Portland Cement Concrete (PCC). In this study, two methods of accelerated curing were used to determine the influence of elevated temperature on the compressive strength of GPC, composed of 50% bottom-ash and 50% fly-ash. GPC specimens were cured using various temperatures including ambient, 30 °C, 45 °C, 60 °C, and 80 °C for 24 h, all followed by 28 days of ambient curing. The highest compressive strength was obtained with steam curing at a temperature of 80 °C for a duration of 24 h. It is of great significance to evaluate elastic modulus of the concrete mixture so that the short-term rigidity of structures subjected to elongation, bending, or compression can be predicted. In this study, a longitudinal Resonant Frequency Test (RFT) as a non-destructive test (NDT) was used to calculate the elastic modulus of both GPC and a comparative PCC mix. Based on the results, PCC had higher resonant frequency (by about 1000 Hz) compared to GPC. A review of empirical models for predicting GPC’s elastic modulus showed that all of the predicted elastic modulus values were lower than experimental values.
Non-commercial Air Purifier—The Effectiveness and Safety
Authors: Mainka Anna , Mucha Walter , Pastuszka Józef S. , Brągoszewska Ewa , Janoszek Agnieszka
Published: June 2020

(1) Background: On the Internet, we can find the guidelines for homemade air purifiers. One of the solutions includes the use of a low-cost ozone generator to decrease the level of odors and biological contaminants. However, the authors do not notify about hazardous effects of ozone generation on human health; (2) Methods: We elaborated our test results on the bacterial and fungal aerosol reduction by the use of two technical solutions of homemade air purifiers. First, including a mesh filter and ozone generator, second including an ozone generator, mesh filter, and carbon filter. (3) Conclusions: After 20 min of ozone generation, the concentration of bacteria decreased by 78% and 48% without and with a carbon filter, while fungi concentration was reduced in the lower range 63% and 40%, respectively. Based on our test results, we proposed a precise periodical operation of homemade air purifier to maintain the permissible level of ozone for the occupants.
Optical and Electronic Properties of Carbon-Based Nanomaterials and Composites
Authors: Agnello Simonpietro , Messina Fabrizio
Published: June 2020

Dear Colleagues, [...]
A Colorimetric Aptamer Sensor Based on the Enhanced Peroxidase Activity of Functionalized Graphene/Fe3O4-AuNPs for Detection of Lead (II) Ions
Authors: Tao Zui , Zhou You , Duan Nuo , Wang Zhouping
Published: June 2020

Lead (II) is regarded as one of the most hazardous heavy metals, and lead contamination has a serious impact on food chains, human health, and the environment. Herein, a colorimetric aptasensor based on the graphene/Fe3O4-AuNPs composites with enhanced peroxidase-like activity has been developed to monitor lead ions (Pb2+). In short, graphene/Fe3O4-AuNPs were fabricated and acted as an enzyme mimetic, so the color change could be observed by chromogenic reaction. The aptamer of Pb2+ was decorated on the surface of the amine magnetic beads by streptavidin–biotin interaction, and the complementary strands of the aptamer and target Pb2+ competed for the binding Pb2+ aptamer. In the presence of Pb2+, aptamers bonded the metal ions and were removed from the system by magnetic separation; the free cDNA was adsorbed onto the surface of the graphene/Fe3O4-AuNPs composites, thus inhibiting the catalytic activity and the color reaction. The absorbance of the reaction solution at 652 nm had a clear linear correlation with the Pb2+ concentration in the range of 1–300 ng/mL, and the limit of detection was 0.63 ng/mL. This assay is simple and convenient in operation, has good selectivity, and has been used to test tap water samples, which proves that it is capable for the routine monitoring of Pb2+.
Biochemical Degradation of Chitosan over Immobilized Cellulase and Supported Fenton Catalysts
Authors: Geng Huawei , Mou Zonggang , Liu Ziyong , Li Fuli , Yang Cheng
Published: June 2020

This paper describes the application of Fe-MCM-48 (Mobil Composition of Matter No.48) and cellulase-MCM-48 catalysts for the depolymerization of chitosan. The results show that H2O2 is a good oxidant for the depolymerization of chitosan in the presence of Fe-MCM-48. The average polymerization degree of the product decreased to 6.1, and decreased to 29.2 when cellulase-MCM-48 was used as a catalyst, because the effect of the enzyme was affected by the molecular structure of chitosan. When both materials were used for depolymerization, the average degree of polymerization sharply decreased to 3.8. The results show that the two degradation methods can promote each other to obtain oligosaccharides with a lower degree of polymerization. This provides a new method for the controllable degradation of chitosan and lays a good foundation for the industrial production of chitosan oligosaccharides with a low degree of polymerization.
One Pot Use of Combilipases for Full Modification of Oils and Fats: Multifunctional and Heterogeneous Substrates
Authors: Arana-Peña Sara , Carballares Diego , Berenguer-Murcia Ángel , Alcántara Andrés , Rodrigues Rafael , Fernandez-Lafuente Roberto
Published: June 2020

Lipases are among the most utilized enzymes in biocatalysis. In many instances, the main reason for their use is their high specificity or selectivity. However, when full modification of a multifunctional and heterogeneous substrate is pursued, enzyme selectivity and specificity become a problem. This is the case of hydrolysis of oils and fats to produce free fatty acids or their alcoholysis to produce biodiesel, which can be considered cascade reactions. In these cases, to the original heterogeneity of the substrate, the presence of intermediate products, such as diglycerides or monoglycerides, can be an additional drawback. Using these heterogeneous substrates, enzyme specificity can promote that some substrates (initial substrates or intermediate products) may not be recognized as such (in the worst case scenario they may be acting as inhibitors) by the enzyme, causing yields and reaction rates to drop. To solve this situation, a mixture of lipases with different specificity, selectivity and differently affected by the reaction conditions can offer much better results than the use of a single lipase exhibiting a very high initial activity or even the best global reaction course. This mixture of lipases from different sources has been called “combilipases” and is becoming increasingly popular. They include the use of liquid lipase formulations or immobilized lipases. In some instances, the lipases have been coimmobilized. Some discussion is offered regarding the problems that this coimmobilization may give rise to, and some strategies to solve some of these problems are proposed. The use of combilipases in the future may be extended to other processes and enzymes.
An Investigation into the Future Changes in Onset and Cessation of Rain and Their Variability over the Aswa Catchment, Uganda
Authors: Iwadra Michael , Odirile P. T. , Parida B. P. , Moalafhi D. B.
Published: June 2020

Future global warming may result in extreme precipitation events leading to crop, environment and infrastructure damage. Rainfall is a major input for the livelihood of peasant farmers in the Aswa catchment where the future rainfall variability, onset and cessation are also likely to be affected. The Aswa catchment has limited rainfall data; therefore, use of secondary datasets from Tropical Rainfall Measuring Mission (TRMM) is considered in this study, based on the close correlation of the recorded and TRMM rainfall. The latter was used to calibrate the statistical downscaling model for downscaling of two general circulation models to simulate future changes in rainfall. These data were analyzed for trends, wet and dry conditions/variability; onset and cessations of rain using the Mann–Kendall test, Standardized Precipitation Index (SPI) and the cumulative percentage mean rainfall method, respectively. Results show future rainfall is likely to increase, accompanied by increasing variability reaching as high as 118.5%. The frequency of SPI values above 2 (extreme wetness) is to increase above current level during mid and end of the century. The highest rainfall variability is expected especially during the onset and cessation months, which are generally expected to come earlier and later, by up to four and five weeks, respectively. The reliability worsens from the midterm (2036–2065) to long term (2066–2099). These likely changes in rainfall quantities, variability, onset and cessation months are some of the key rainfall dynamics that have implications for future arable agriculture, environment and water resource availability and planning over the Aswa catchment, as is increasingly the case elsewhere.
Surface Temperature Trend Estimation over 12 Sites in Guinea Using 57 Years of Ground-Based Data
Authors: Loua René Tato , Bencherif Hassan , Bègue Nelson , Mbatha Nkanyiso , Portafaix Thierry , Hauchecorne Alain , Sivakumar Venkataraman , Bamba Zoumana
Published: June 2020

Trend-Run model was performed to estimate the trend in surface temperatures recorded at 12 sites in Guinea from 1960 to 2016 and to examine the contribution of each climate forcing. The coefficient of determination (R2) calculated varies between 0.60 and 0.90, it provides total information about the simulation capability of the model. The decadal trend values also calculated show an upward trend (between 0.04 °C ± 0.06 °C decade−1 and 0.21 °C ± 0.06 °C decade−1). In addition, forcings’ contributions were quantified, and the annual oscillation (AO) contribution is higher for most of the stations, followed by semiannual oscillation (SAO). Among the forcings, the tropical Northern Atlantic (TNA) contribution is greater than that of the sunspot number (SSN), Niño3.4 and Atlantic Niño (AN). Moreover, the Mann-Kendall test revealed a positive significant trend for all stations except at the Macenta site. Additionally, with sequential Mann-Kendall test, trend turning points were found only for the stations of Mamou, Koundara and Macenta at different dates. The temperature anomalies depict warming episodes (1970s, 1980s, 1984 and 1990s). Since then, the temperature is consistently increasing over the country. A significant warming has been shown, which might be further investigated using these models with additional contributing factors.
Can Special Light Glasses Reduce Sleepiness and Improve Sleep of Nightshift Workers? A Placebo-Controlled Explorative Field Study
Authors: Aarts Mariëlle P. J. , Hartmeyer Steffen L. , Morsink Kars , Kort Helianthe S. M. , de Kort Yvonne A. W.
Published: June 2020

Nightshift workers go against the natural sleep–wake rhythm. Light can shift the circadian clock but can also induce acute alertness. This placebo-controlled exploratory field study examined the effectiveness of light glasses to improve alertness while reducing the sleep complaints of hospital nurses working nightshifts. In a crossover within-subjects design, 23 nurses participated, using treatment glasses and placebo glasses. Sleepiness and sleep parameters were measured. A linear mixed model analysis on sleepiness revealed no significant main effect of the light intervention. An interaction effect was found indicating that under the placebo condition, sleepiness was significantly higher on the first nightshift than on the last night, while under the treatment condition, sleepiness remained stable across nightshift sessions. Sleepiness during the commute home also showed a significant interaction effect, demonstrating that after the first nightshift, driver sleepiness was higher for placebo than for treatment. Subjective sleep quality showed a negative main effect of treatment vs. placebo, particularly after the first nightshift. In retrospect, both types of light glasses were self-rated as effective. The use of light glasses during the nightshift may help to reduce driver sleepiness during the commute home, which is relevant, as all participants drove home by car or (motor) bike.
Enzyme Loading in Internally-Coated Capillary Tubes Via Kinetic Doping
Authors: Jensen Jessica M. , Yip Wai Tak
Published: June 2020

Development of capillary tubes internally doped with enzymes is of great interest for microfluidic reactions, and kinetic doping could provide a facile, inexpensive method for their manufacture. Kinetic doping has previously been demonstrated to have a high loading capacity with thin films coated on flat-surface coverslips. Dip coating of these surfaces was developed with the eventual intention to coat different shapes and sizes of substrates. In this study, we expanded the use of kinetic doping to internally-coated capillary tubes. Parameters for internally doping capillary tubes were developed with rhodamine 6G, which produced internally-coated thin films with a 90 nm thickness. Horseradish peroxidase (HRP) was then loaded into the capillary tubes, with a 47,000× increase in concentration over the loading solution. After excluding surface-adsorbed protein, the increase in HRP concentration in the thin films over the loading solution was determined to be 9850×. The activity of the loaded HRP was determined to be 0.019 ± 0.003 U/mg and shown to have a stronger resistance to denaturation by methanol.
Polyethylene Glycol (PEG) Modified Porous Ca5(PO4)2SiO4 Bioceramics: Structural, Morphologic and Bioactivity Analysis
Authors: Kumar Pawan , Saini Meenu , Kumar Vinod , Dehiya Brijnandan S. , Sindhu Anil , Fouad H. , Ahmad Naushad , Mahmood Amer , Hashem Mohamed
Published: June 2020

Bioceramics are class of biomaterials that are specially developed for application in tissue engineering and regenerative medicines. Sol-gel method used for producing bioactive and reactive bioceramic materials more than those synthesized by traditional methods. In the present research study, the effect of polyethylene glycol (PEG) on Ca5(PO4)2SiO4 (CPS) bioceramics was investigated. The addition of 5% and 10% PEG significantly affected the porosity and bioactivity of sol-gel derived Ca5(PO4)2SiO4. The morphology and physicochemical properties of pure and modified materials were evaluated using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR), respectively. The effect of PEG on the surface area and porosity of Ca5(PO4)2SiO4 was measured by Brunauer–Emmett–Teller (BET). The results obtained from XRD and FTIR studies confirmed the interactions between PEG and CPS. Due to the high concentration of PEG, the CPS-3 sample showed the largest-sized particle with an average of 200.53 µm. The porous structure of CPS-2 and CPS-3 revealed that they have a better ability to generate an appetite layer on the surface of the sample when immersed in simulated body fluid (SBF) for seven days. The generation of appetite layer showed the bioactive nature of CPS which makes it a suitable material for hard tissue engineering applications. The results have shown that the PEG-modified porous CPS could be a more effective material for drug delivery, implant coatings and other tissue engineering applications. The aim of this research work is to fabricate SBF treated and porous polyethylene glycol-modified Ca5(PO4)2SiO4 material. SBF treatment and porosity of material can provide a very useful target for bioactivity and drug delivery applications in the future.
A Comprehensive and Systematic Survey on the Internet of Things: Security and Privacy Challenges, Security Frameworks, Enabling Technologies, Threats, Vulnerabilities and Countermeasures
Authors: Obaidat Muath A. , Obeidat Suhaib , Holst Jennifer , Al Hayajneh Abdullah , Brown Joseph
Published: June 2020

The Internet of Things (IoT) has experienced constant growth in the number of devices deployed and the range of applications in which such devices are used. They vary widely in size, computational power, capacity storage, and energy. The explosive growth and integration of IoT in different domains and areas of our daily lives has created an Internet of Vulnerabilities (IoV). In the rush to build and implement IoT devices, security and privacy have not been adequately addressed. IoT devices, many of which are highly constrained, are vulnerable to cyber attacks, which threaten the security and privacy of users and systems. This survey provides a comprehensive overview of IoT in regard to areas of application, security architecture frameworks, recent security and privacy issues in IoT, as well as a review of recent similar studies on IoT security and privacy. In addition, the paper presents a comprehensive taxonomy of attacks on IoT based on the three-layer architecture model; perception, network, and application layers, as well as a suggestion of the impact of these attacks on CIA objectives in representative devices, are presented. Moreover, the study proposes mitigations and countermeasures, taking a multi-faceted approach rather than a per layer approach. Open research areas are also covered to provide researchers with the most recent research urgent questions in regard to securing IoT ecosystem.
Effects of Thermal Annealing on Optical Properties of Be-Implanted GaN Thin Films by Spectroscopic Ellipsometry
Authors: Wei Wenwang , Wang Jiabin , Liu Yao , Peng Yi , Maraj Mudassar , Peng Biaolin , Wang Yukun , Sun Wenhong
Published: June 2020

Wide bandgap III-V compounds are the key materials for the fabrication of short-wavelength optical devices and have important applications in optical displays, optical storage devices and optical communication systems. Herein, the variable-angle spectroscopic ellipsometry (SE) measurements are performed to investigate the thickness and optical properties of beryllium-implanted gallium nitride thin films that have been deposited on (0001) sapphire substrates by using low-pressure metalorganic chemical vapor deposition (LPMOCVD). The film layer details are described by using Parametric Semiconductor oscillators and Gaussian oscillators in the wavelength range of 200–1600 nm. The thickness, refractive indices and extinction coefficients of the Be-implanted films are determined at room temperature. Analysis of the absorption coefficient shows that the optical absorption edge of Be-implanted films changes from 3.328 eV to 3.083 eV in the temperature range of 300–850 K. With the variable temperature, Eg is demonstrated to follow the formula of Varshni. A dual-beam ultraviolet–visible spectrophotometer (UV–VIS) is used to study the crystal quality of samples, indicating that the quality of rapid thermal annealing (RTA) sample is better than that unannealed sample. By transport of ions in matter (TRIM) simulation and SE fitting the depths of Be implanted gallium nitride (GaN) films are estimated and in good agreement. The surface and cross-section morphologies are characterized by atomic force microscopy (AFM) and scanning electron microscope (SEM), respectively. The surface morphologies and thickness measurements of the samples show that RTA can improve crystal quality, while increasing the thickness of the surface roughness layer due to partial surface decomposition in the process of thermal annealing.
Crystal Structure and Theoretical Investigation of Thiobarbituric Acid Derivatives as Nonlinear Optical (NLO) Materials
Authors: Sharma Anamika , Barakat Assem , Al-Rasheed Hessa H. , Al-Majid Abdullah Mohammed , Yousuf Sammer , Choudhary M. Iqbal , El-Faham Ayman , de la Torre Beatriz G. , Albericio Fernando
Published: June 2020

Here we report on the crystal structure of three enamine/imine TBA derivatives (1–3). Since the derivatives can take the form of enamine or imine tautomers, theoretical calculations were made to confirm that the former predominates due to higher stability (thermodynamic calculations). The enamines’ form was further corroborated by high activation energy (ΔG≠; which is >60 kcal/mol in all the cases), thus requiring a large amount of energy to pass the barrier (kinetics calculations). Furthermore, 1–3 were found to show high static hyperpolarizability (βtot), thereby making them potential candidates as nonlinear materials for electro-optical devices and crystal engineering.
The Development of Ultrafast Electron Microscopy
Authors: Aseyev Sergei , Ryabov Evgeny , Mironov Boris , Ischenko Anatoly
Published: June 2020

Time-resolved electron microscopy is based on the excitation of a sample by pulsed laser radiation and its probing by synchronized photoelectron bunches in the electron microscope column. With femtosecond lasers, if probing pulses with a small number of electrons—in the limit, single-electron wave packets—are used, the stroboscopic regime enables ultrahigh spatiotemporal resolution to be obtained, which is not restricted by the Coulomb repulsion of electrons. This review article presents the current state of the ultrafast electron microscopy (UEM) method for detecting the structural dynamics of matter in the time range from picoseconds to attoseconds. Moreover, in the imaging mode, the spatial resolution lies, at best, in the subnanometer range, which limits the range of observation of structural changes in the sample. The ultrafast electron diffraction (UED), which created the methodological basis for the development of UEM, has opened the possibility of creating molecular movies that show the behavior of the investigated quantum system in the space-time continuum with details of sub-Å spatial resolution. Therefore, this review on the development of UEM begins with a description of the main achievements of UED, which formed the basis for the creation and further development of the UEM method. A number of recent experiments are presented to illustrate the potential of the UEM method.
Tunable RF Filters Based on Liquid Crystal for Space Applications
Authors: Kaesser Tobias , Fritzsch Carsten , Franz Michael
Published: June 2020

On board of communication satellites, there are numerous RF filters in the payload used for guiding wanted signals as desired and for rejecting unwanted signals such as not to interfere with wanted signals. At present, satellites have a long lifetime (15 years at least for a typical geostationary communication satellite) and there is also time elapsing between its design and the start of in-orbit service (2 years at least). On the other hand, conventional RF filters for satellite applications are fixed frequency. Therefore, there is a growing demand for in-orbit tunable filters to be able to cope with changes in the market situation during that long time. Also, there are communication systems evolving that rely on tunable devices used for adaptive filtering or steering. This article reports on in-orbit tunable bandpass filters employing liquid crystal material and operating at 20 GHz, and especially on design aspects dealing with the harsh space environment, on the operating principles for commanding the filters on board the satellite, and on a qualification campaign passed successfully. A demonstrator unit is in manufacturing for in-orbit verification.