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1
Content available remote Development of quantitative HPTLC methods for dolutegravir, lamivudine, and tenofovir disproxil fumarate in a combination pharmaceutical product using a model process published earlier for transfer of minilab TLC screening methods to HPTLC-densitometry
Gu Y., Zeng B., Sherma J.
Acta Chromatographica
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2020
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Vol. 32, no. 3
199--202
EN
High-performance thin-layer chromatography (HPLTC)–densitometry methods are described for the analysis of the anti(retro)virals dolutegravir (D), lamivudine (L), and tenofovir disoproxil fumarate (TDF) in a pharmaceutical tablet product. To the best of our knowledge, no previous quantitative planar chromatography method has been reported in the literature for this combination formulation. The method for L was transferred from a thin-layer chromatography (TLC) screening method published in the Global Pharma Health Fund (GPHF) Minilab Manual designed for identification of counterfeit and substandard drug products using a model process published earlier. D and TDF are not included in the list of drugs for which TLC screening methods are published for the Minilab, but HPTLC–densitometry procedures were developed for them using the transfer process guidelines. L was analyzed simultaneously with TDF on Merck Premium Purity silica gel 60 F plates using the mobile phase ethyl acetate–methanol–acetone–concentrated ammonium hydroxide (30:7:3:1) and densitometric scanning at 254 nm. D was analyzed on a second plate by scanning at 366 nm after chromatography with the chloroform–methanol–formic acid (32:8:2) mobile phase. Data for all three drugs are shown to meet the requirements of the model transfer process for calibration curve r values, assay of tablets relative to their label values, peak purity/peak identity tests, and validation by standard addition analysis of samples spiked at 50%, 100%, and 150% of the label value of active ingredients. A TLC screening method for TDF in the combination product was developed and published online with open access.
2
Content available remote Transfer of TLC screening methods to quantitative HPTLC–densitometry methods for pharmaceutical products containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl
Zeng B., Gu Y., Sherma J.
Acta Chromatographica
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2019
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Vol. 31, no. 4
246--249
EN
Transfer of seven thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab protocols for screening counterfeit pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)–densitometry methods was performed using a model process published previously. The developed and validated methods for tablets containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl involved the use of only relatively inexpensive and nontoxic solvents, Merck KGaA Premium Purity HPTLC silica gel 60 F254 plates, semi-automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification. In addition, previously transferred HPTLC–densitometry methods for azithromycin and for cephalexin were used to analyze a new product of each drug to demonstrate the applicability of the methods.
3
Content available remote Parametric study on cement treated aggregate panel under impact load
Ali S., Liu X., Thambiratnam D., Fawzia S., Gu Y., Wu J., Remennikov A.
Archives of Civil and Mechanical Engineering
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2018
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Vol. 18, no. 2
622--629
EN
The cement treated aggregate (CTA) is increasingly used as base or sub-base layer for pavement to withstand various traffic and dynamic loads. Under extreme events, the CTA layer of the pavement is expected to absorb significant amount of impact energies subjected to different loading conditions including accidents, mobile vehicles, heavy aircrafts, machinery, or even terrorist attack. However, no research has been found on the resistance of CTA under drop weight impact load. To fill up this gap, a detailed study was carried out to investigate the impact resistance of CTA under impact loading through both experimental and finite element analysis (FEA). Moreover, detailed parametric studies were carried out based on the validated model to determine the significance of selected key parameters on the impact resistance of CTA.
4
Content available How foot morphology changes influence shoe comfort and plantar pressure before and after long distance running?
Mey Q., Gu Y., Sun D., Fernandez J.
Acta of Bioengineering and Biomechanics
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2018
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Vol. 20, no. 2
179--186
EN
Prolonged running has been popularized globally in recent decades. This study was aimed to reveal information about foot morphology, shoe comfort and plantar loading among recreational heel-strike runners. Methods: Twenty-six runners participated in foot morphology, perceived scores and peak pressure tests after 10- and 20-km track running. The foot morphology was measured using a 3D foot scanner, perceived scores were recorded using a visual analogue scale and plantar pressure was measured via insole plantar pressure measurement system. The statistical significance level was set at 0.05. Results: The heel midsole materials properties were measured before and after 20 km. Significant changes were observed in ball width and girth, arch height and foot volume. The perceived scores showed significance in overall, forefoot and heel comfort, arch support and forefoot width. Peak pressure to the heel, medial mid-foot and metatarsal greatly increased. The first metatarsal showed consecutive increase from static to 10 km, and 20 km, while big-toe showed a decrease. Conclusions: The morphology variations and forefoot loading concentration may lead to discomfort and possibly imply dermatological problems and metatarsal bone stress, particularly on the first metatarsal. Combining changes of heel midsole property, knowledge of foot shape, shoe perception and plantar pressure is of great value for recreational long-distance running shoes design and materials selection.
5
Content available Looped-chain-based active current sharing strategy in DC microgrids
Li D., Liu Y., Gu Y., Qi H.
Archives of Electrical Engineering
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2017
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Vol. 66, nr 3
559--569
EN
The integration of renewable energy sources in modern electric grids have drawn increasing attention nowadays. In order to effectively manage large-scale renewable energy sources and achieve flexible and efficient operation, the concept of microgrids have been proposed. Considering the nature of DC outputs in many distributed energy resources (DERs), DC microgrids have been extensively studied in the past years. Among the operational issues in DC microgrids, current sharing issues have become an important topic since it is highly relevant to the operation of DC microgrids. By adopting a proper design of current sharing strategy in DC microgrids, the current rating violations in each interface converter can be successfully avoided. In this paper, a looped-chainbased active current sharing strategy is proposed to realize high accuracy current sharing in DC microgrids. In particular, the output current is shared between the neighboring interface converters. Hence, following a clockwise or counter-clockwise order, a loopedchain- based control diagram can be established to share the reference value of the output current. A final status in the whole DC microgrid is that the output current of every interface converter is equalized. Hence, the desired current sharing objective can be satisfied. A MATLAB simulation model is established to verify the proposed loopedchain- based active current sharing strategy in DC microgrids.
6
Content available Investigating biomechanical function of toes through external manipulation integrating analysis
Mei Q., Fernandes J., Hume P., Gu Y.
Acta of Bioengineering and Biomechanics
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2016
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Vol. 18, no. 1
97--102
EN
Purpose: This study was aimed to investigate the function of toes while running through comparing bound toes by external-manipulation with natural separate toes by evaluating kinematics and plantar pressure analysis. Methods: Seven habitually barefoot male runners participated in the running test under toes binding and non-binding conditions, and Vicon and Novel insole plantar pressure measurement were conducted synchronously to collect kinematics and foot loading. Results: Ankle kinematics showed larger non-significant range of motion in the frontal plane while running with toes non-binding.The medial forefoot had a smaller force time integral, and with hallux had a larger force time integral than those of running with toes binding, with significance level p < 0.05. Conclusions: While no significance existed between bound and non-bound toes in kinematics, the medial forefoot had a smaller foot impulse and the hallux had a larger foot impulse for those with non-binding feet. This suggests that other functions such as the active gripping action of toes might be important for the efficiency of the foot windlass mechanism (the plantar fascia support), which would be beneficial for running performance improvement and foot injury prevention.
7
Content available Effects of performance level on lower limb kinematics during table tennis forehand loop
Qian J., Zhang Y., Baker J. S., Gu Y.
Acta of Bioengineering and Biomechanics
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2016
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Vol. 18, no. 3
149--155
EN
Understanding of biomechanics is important in performance development since each skill has a fundamental mechanical structure. The purpose of this study was to investigate differences in lower limb kinematics during table tennis forehand loop between superior players (SP) and intermediate players (IP). Thirteen male players as superior and thirteen as intermediate participated in this test. A VICON motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematic and contact area data, respectively. Participants were asked to execute single forehand loop against topspin ball with maximal power. Key findings were that SP showed significantly larger hip flexion and knee external rotation at backward-end and larger hip internal rotation and extension at forward-end compared with IP. Contact areas at both events were larger for SP. In addition, SP showed significantly larger joints angular changing rate during forward swing at the ankle and hip. Results indicated that SP possessed better ability of using lower limb drive in forehand loop.
8
Content available Effects of unstable elements with different hardness on lower limb loading
Li F., Mei Q., Gu Y.
Acta of Bioengineering and Biomechanics
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2015
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Vol. 17, no. 2
85--92
EN
Purpose: Osteoarthritis of the knee is one of the most common diseases. For this chronic disease, modified footwear structure can effectively prevent and relieve disease of the knee. The aim of this study was to explore the effects of shoe surface elastic modulus on external knee adduction moment and ground reaction force and foot loading characteristics. Methods: Sixteen healthy female volunteers were recruited, and each subject performed five walking trials under two shoes condition. The lower limb loading data was collected using force platform and in-sole pressure measurement system. Results: The results showed that the external knee adduction moment was decreased in all stance phase when wearing SS (unstable shoes with soft unstable elements), compared with HS (unstable shoes with hard unstable elements). The ground reaction force showed no obvious change under two shoes condition. Additionally, compared with HS, plantar pressure transferred from medial foot to lateral foot when wearing SS. Along with changes of contact areas, average pressure and impulse had also presented this tendency. Conclusions: These results can provide some scientific evidence and suggestions for footwear companies, and for the foot plantar medial injury disease has also certain applicability.
9
Content available remote Electronic structure and possible martensitic transformation in Ni2FeIn alloy
Gu Y., Xue F, Zhao G, Liu G., Liu Y., Li S.
Materials Science Poland
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2014
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Vol. 32, No. 3
396—401
EN
The electronic structure and magnetic properties of Heusler alloys (Ni2FeIn) have been studied by first principle calculations. The possible tetragonal martensitic transformation has been predicted and the structure optimization was made on cubic austenitic Ni2FeIn in Cu2MnAl type. The equilibrium lattice constant of austenitic Ni2FeIn is 6.03 A° . In tetragonal phase, the global energy minimum occurs at c=a = 1.29. The corresponding equilibrium lattice constants for martensite Ni2FeIn are a = b = 5.5393 °A and c = 7.1457 A° , respectively. In the austenitic phase, EF is located at the peak in the minority DOS for c=a = 0.96 to 1.20, but in the martensitic phase, EF moves to the bottom of the valley in the minority DOS, reducing the value of N(EF ) effectively. Both austenitic and martensitic phases are ferromagnetic and the Ni and Fe partial moments contribute mainly to the total moments. Therefore, the martensitic transformation behavior in Ni2FeIn is predicted.
10
Content available remote Sensorless Vector Control of AC Servo System with Artificial Neural Network Observer and Fuzzy Speed Controller
Gu Y., Shi Y., Wang J.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 1b
150-153
EN
The intelligent sensorless control for the permanent magnet synchronous motor (PMSM) based AC servo system is introduced in this paper. The determination of rotor position and thereby speed are realized by estimating back electromotive force (EMF) using two artificial neural network (ANN) observers. In addition, the Fuzzy-sliding model control (FSMC) was employed to track the servo speed at the speed loop. The control experiments using the dSPACE simulation platform has validated the efficiency of the newly proposed control method.
PL
Przedstawiono metodę inteligentnego bezczujnikowego sterowania maszyną synchroniczną z magnesami trwałymi. Użyto obserwatora bazującego na sieciach neuronowych. Dodatkowo wykorzystano kontroler bazujący na logice rozmytej do śledzenia prędkości.
11
Content available Review of the Photodecomposition of Some Important Energetic Materials
Sun Y., Shu Y., Xu T., Shui M., Zhao Z., Gu Y., Wang X.
Central European Journal of Energetic Materials
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2012
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Vol. 9, nr 4
411-423
EN
The photodecomposition mechanisms of energetic materials vary with molecular structure, photodissociation wavelength, the phase of the material, experimental pressure and temperature etc. In this paper, the significant progress on photodecomposition studies of some important energetic materials achieved in recent years is introduced in detail, including nitromethane, DMNA (dimethylnitramine), TATB (1,3,5-triamino-2,4,6-trinitrobenzene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (1,3,5,7-tetranitro-1,3,5,7- tetrazacycloctane) and CL-20 (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane). The difficulties and prospects of photodecomposition research of energetic materials are also indicated.
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