english EUGENIA TANASĂ
Rezumat
Separarea fotoelectrochimică (PEC) a apei folosind energia solară apare ca o strategie extrem de promițătoare pentru generarea durabilă de hidrogen și stocarea energiei. Cercetările actuale în acest domeniu evidențiază hematitul ca material fotoanod adecvat pentru separarea apei datorită proprietăților sale favorabile: este un semiconductor de tip n, posedă o bandă interzisă adecvată pentru absorbția luminii vizibile, prezintă o stabilitate chimică ridicată și este disponibil din abundență pe Pământ. Acest review prezintă diverse strategii de modificare a hematitului pentru a-i îmbunătăți performanța. Aceste modificări includ doparea elementelor, proiectarea și fabricarea nanostructurilor, integrarea co-catalizatorilor, formarea heterostructurilor și interdependența dintre structura și performanța hematitului.
Cuvinte cheie
energie solară, hematită, fotoanozi
XIANWU JING, XIAOJIN ZHOU, TENG GONG, TAO WANG, YANG WANG, GUOQING LIU, KAIJUN WANG
Rezumat
This research employed molecular dynamics simulations to explore the distribution of sodium dodecyl sulfate (SDS) at the n-hexane/water interface. Once the SDS concentration surpasses the critical micelle concentration(cmc), a large portion of SDS migrates to the n-hexane/water interface, establishing a thin layer where sulfonic acid groups are oriented towards the water phase and carbon-hydrogen chains are directed towards n-hexane, a small amount of SDS forms spherical micelle with sulfonic acid groups facing the water phase, while carbon-hydrogen chains aggregate in the interior of these spherical structures. The sulfonic acid group of SDS forms multiple h-bonds with water, shows strong interaction energy; while the carbon hydrogen chain itself has only weak van der Waals interactions with surrounding molecules. The thickness of SDS- layer at the n-hexane/water interface is about 2.06 nm, with a maximum number density of about 0.25 per nm3, and average area occupied by a single SDS- is about 0.21 nm2. According to radial distribution function (RDF) result, due to the attractive effect of positive and negative charges, the first coordination layer of Na+ ions and oxygen atoms on sulfonic acid groups is about 0.21 nm. This study investigated the distribution of SDS at n-hexane/water interface, vividly demonstrating the mechanism by which SDS reduces the interfacial tension between oil and water, and providing guidance for oilfield development.
Cuvinte cheie
Interfață N-hexan/apă; Simulare dinamică moleculară; Dodecil sulfat de sodiu; Analiza interacțiunii slabe
ZHI LI, PING JIANG
Rezumat
To address the performance limitations of single silica (SiO2) encapsulated phase change materials, a novel shape-stable composite microencapsulated phase change material (CA/CS/SiO2 MEPCM) was prepared using the sol-gel method. Capric acid (CA) was used as the phase change material (PCM), while chitosan/silica (CS/SiO2) served as the composite encapsulation material. Fourier transform near infrared spectroscopy (FT-NIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the chemical structure, crystalline phase, and microstructure of the CA/CS/SiO2 MEPCM. The thermal storage properties and thermal stability of the MEPCM were analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SEM results indicated that CA was effectively encapsulated within the CS/SiO2 shell, and the reticulated structure of the shell contributed to the high shape stability of the MEPCM. The results demonstrate that CA is effectively encapsulated within the CS/SiO2 shell, and the network structure of the shell significantly enhances the shape stability of the MEPCM. The encapsulation process preserves the chemical integrity of CA, as no structural changes were observed. The synthesized MEPCM exhibits excellent sealing performance at 102 °C, and the thermal stability of the CS/SiO2 composite shell surpasses that of conventional single-shell structures. Furthermore, the material displays a moderate phase transition temperature and a maximum latent heat of 69.38 J/g, meeting the requirements for variable thermal regulation. In conclusion, the CA/CS/SiO2 MEPCM developed in this study is a green, non-toxic, and structurally stable phase change material with a tunable phase transition temperature, offering promising potential for sustainable thermal energy storage applications.
Cuvinte cheie
acid capric, chitosan, dioxid de siliciu, materiale microîncapsulate cu schimbare de fază
VISWANATH KRISHNAN, MOHAN EKAMBARAM, VINOTHKUMAR RAVI, SHEEBA RANI SOUNDARAPANDIAN
Rezumat
In this study, powdered magnesium and aluminum particles were combined with a smaller quantity of silicon carbide (SiC) particles, and the sintering process was used to form the metal matrix composite (MMC). The specimens were made at three distinct temperatures such as 4500C, 5000C, and 5400C. The addition of silicon carbide to the magnesium and aluminium leads to increase the hardness. Based on the scanning electron microscopy (SEM), a large number of holes were commensurate with the sintered specimen produced at the minimal sintering temperature. The development of pore was significantly reduced at high temperature, and strong metallurgical bonding was also attained. The hardness of the sintered specimen was also raised at high sintering temperatures. When compared to other traditional machining methods, the reason for using spark erosion machining or electric discharge machining (EDM) is to maintain the optimal surface roughness (SR) and increase material removal rate (MRR). An atomic force microscopy (AFM) and SEM examination was carried out specifically to evaluate the surface parameters of the magnalium MMC. The pit and valley surface was observed in the machining surface. Current and voltage played a crucial role in metal removal and surface roughness.
Cuvinte cheie
Compozit Magnalium, sinterizare, metalurgie a pulberilor, duritate, prelucrare prin eroziune prin scânteie
QIAN HONG, XIAOFENG CHEN, WEIQING YU, XIAOXIAO MA, YANBING WANG, CHONGQING WANG, CHAO LIU
Rezumat
Faced with the defects of engineering disturbed slope soil, such as easy erosion and evaporation of water, this paper uses polyvinyl alcohol (PVA) hydrogel as a soil conditioner to improve the water erosion resistance and water retention performance of engineering disturbed slope soil, and studies the vegetation performance and microstructure of modified soil. The results showed that PVA hydrogel changed the soil structure by using its excellent cementation and water holding capacity. PVA hydrogel completely wrapped the soil particles to form the overall structure of network gel, which significantly improved the soil erosion resistance, water stability and water retention capacity of the soil. With the increase of PVA concentration, the soil erosion resistance, water stability and water retention performance are significantly improved. In addition, the effect of increasing PVA concentration on soil vegetation performance shows a trend of first strengthening and then weakening, with the best soil vegetation performance observed when PVA concentration was 3%. The results show that PVA hydrogel has important application value for reducing soil and water loss of engineering disturbed slope and promoting vegetation restoration.
Cuvinte cheie
pantă perturbată, restaurare ecologică, rezistență la eroziune, performanță de retenție a apei, performanță a vegetației
PREPARATION METHOD OF DIATOM-BASED EARTH AND ZINC OXIDE COMPOSITE HIGH-DENSITY POLYETHYLENE MATERIAL
KUN LU, HAN KONG, YAOWEN ZHANG, JIAXING ZHU, YUANYUAN DING, XIYU HUANG, CHAO ZHANG
Rezumat
In order to cope with the increasingly severe environmental nanotechnology problems and energy shortage, the development of green new materials has become an inevitable trend in today society. In this paper, a preparation method and application of diatom-based earth and zinc oxide composite high-density polyethylene material are provided, which belong to the solid adsorbent composition material. Firstly, high-density polyethylene composites were prepared according to a certain proportion of diatom-based earth and zinc oxide and polyethylene. Then, to improve its performance and UV resistance, Tinuvin 770 is added and mixed with a composite polyethylene material in a gear mixer. Subsequently, the twin-screw extruding machine is set to a certain temperature and speed, extruded, and the extrusion is cut into composite pellets using a tray machine. Finally, these composite pellets are injected into the injection molding machine, where the target mold is selected and molded. At the same time, it can be used as a food packaging bag material, which can inhibit the growth of Staphylococcus aureus and E. bacillus, so that it has the minimum UV stabilizer content, which is a cost-effective and high-performance choice, and its ability to block ultraviolet rays is strong, and it can well protect the quality of packaged food.
Cuvinte cheie
diatomee, oxid de zinc, polietilenă de înaltă densitate, Tinuvin 770
IOANA ION, CIPRIAN MIHAI MITU, EMANUEL VIRGIL MARINESCU, ANDREI CUCOS, ALINA RUXANDRA CARAMITU
Rezumat
Acest studiu prezintă o metodă ecologică de sinteză a unui hidrogel hibrid (HH) pentru remedierea apelor uzate, bazată pe dublă reticulare prin îngheț–dezgheț și iradiere cu raze gama. Matricea polimerică formată din alcool polivinilic (PVA) și carboximetil celuloză (CMC) a fost funcționalizată cu nanoparticule de argint (AgNPs) și oxid de grafen decorat cu AgNPs (AgNPs/GO) pentru a îmbunătăți proprietatile mecanice, adsorbția și activitatea fotocatalitica. Albastrul de metilen (MB) a fost utilizat ca model de poluant. Functionalizarea cu AgNPs și AgNPs/GO determina îmbunătățiri semnificativa a capacitații de adsorbție/decolorare la echilibru: cu 20% cu HAgNP și cu 130% pentru HAgNP/GO; gradul de gonflare cu 6% pentru HAgNP și cu 109% pentru HAgNP/Go; o crestere a rezidului carbonic total la 800°C, la aproximativ 20% datorită rolului catalitic al AgNPs și GO. Efectele sinergice ale CMC, GO și AgNPs îmbunătățesc atât performanța structurală, cât și cea funcțională a hidrogelurilor, poziționând această abordare ca o cale promițătoare pentru tehnologiile avansate de tratare a apelor uzate.Studiul propune o strategie de sinteza a hidrogelurilor pentru tratarea apelor, oferind în același timp o soluție sustenabilă de sfârșit de ciclu/ reciclare, prin pirogenare controlată, cu obtinere de noi produce carbonice cu valore adaugata.
Cuvinte cheie
remedierea apelor uzate, hidrogeluri hibride, nanoparticule de argint, oxid de grafen, oxid de grafen decorat cu nanoparticule de argint, adsorbtia de albastru de metilen
WEI ZHENG
Rezumat
This work presents an optoelectronic study of cobalt-doped nano-TiO2 camouflage films prepared via a non-hydrolytic sol–gel route and examines their suitability for device integration. Photoluminescence (PL) and UV–Vis absorption measurements show that the films possess a tunable bandgap (3.12–3.24 eV) and exhibit a rapid photoconductive response under visible illumination, with a rise time of about 15 ms and a decay time of roughly 25 ms. SEM observations indicate a highly uniform film morphology, and UV aging tests verify that the coatings retain their structural and optical stability in ambient conditions. When these materials are incorporated into prototype thin-film photodetectors, the devices achieve an on/off photocurrent ratio exceeding 10³ and a responsivity of 0.15 A/W at 450 nm, pointing to their practical promise for adaptive optical filters and smart window coatings. In addition, assessment of visual performance shows that nanoscale optical camouflage layers deliver an average increase of 0.91 points in visual impact over conventional materials, underscoring the capacity of nanoscale optical and electronic architectures to reshape graphic design by enabling more dynamic and aesthetically compelling visual experiences.
Cuvinte cheie
Nanoscale Optical Camouflage Materials, Electronic and Optoelectronic Properties, Nano Titanium Dioxide, Graphic Design Enhancement, Sol-Gel Process
CHUFENG TAO
Rezumat
A novel nanoscale optoelectronic imaging platform is presented that leverages quantum-dot–sensitized sensors together with a hybrid clustering strategy to realize ultra-high-speed acquisition and analysis of rapid nanoscale phenomena. By embedding CdSe/ZnS quantum dots into a plasmonic imaging circuit and feeding the sensor output into a modified k-means routine steered by an artificial fish swarm algorithm (AFSA), data redundancy is suppressed and representative keyframes are extracted in real time. Experiments tracking plasmonic nanoparticle motion under pulsed excitation show a 9.96 % rise in clustering accuracy and a 7.44 % increase in recall relative to standard k-means, accompanied by a 0.086 improvement in the silhouette coefficient. Collectively, these results demonstrate concurrent gains in spatial resolution (down to 50 nm) and temporal resolution (sub-microsecond). Demonstrations in in-situ nanomanufacturing quality monitoring and single-molecule bioimaging further illustrate the platform’s applicability across nanoelectronics and optoelectronic systems.
Cuvinte cheie
Nanoscale Optoelectronics, Ultra-High-Speed Optical Imaging, Nanomaterials in Imaging Technology, Image Processing Algorithms, High-Speed Phenomena Analysis
ELENA CHIȚANU, MIRELA MARIA CODESCU, VIRGIL MARINESCU, ISTVAN BORBÁTH
Rezumat
Nanomaterialele au atras o atenție considerabilă datorită metodelor lor adaptabile de sinteză și gamei largi de aplicații funcționale. Printre acestea, nanoparticulele de SiO2 au atras o atenție semnificativă datorită proprietăților lor fizico-chimice controlabile, care pot fi proiectate cu precizie pentru aplicații biomedicale specifice. De la introducerea sa în 1968, metoda Stöber - în ciuda faptului că a suferit doar mici modificări - a rămas cea mai utilizată abordare pentru sinteza SiO2 la scară nanometrică. Datorită morfologiei și dimensiunii particulelor lor, nanoparticulele de SiO₂ sunt deosebit de potrivite pentru utilizarea în tehnici avansate de fabricație, cum ar fi imprimarea tridimensională (3D), în special în aplicațiile de inginerie biomedicală, inclusiv regenerarea țesutului osos. În astfel de situații, nanoparticulele de SiO₂ sunt de obicei dispersate în suspensii, unde cunoașterea sarcinii lor de suprafață este esențială, deoarece joacă un rol critic în mecanismele ce guvernează agregarea și stabilitatea coloidală. Cu toate acestea, tehnicile de măsurare existente nu permit cuantificarea directă și precisă a sarcinii de suprafață; în consecință, acest parametru este adesea estimat indirect, prin determinarea potențialului zeta. Acest studiu prezintă influența concentrației de tetraetilortosilicat (TEOS) asupra stabilității suspensiilor de SiO2. Nanoparticulele de SiO2 au fost preparate prin tehnica clasică Stöber, cu geometrie sferică uniformă și dimensiuni medii variind în intervalul 152 nm până la 681 nm, datorită creșterii concentrației de TEOS. Pentru a determina potențialul zeta, suspensii conținând 0,05 % masice SiO2 au fost preparate în soluții cu valori ale pH-ului cuprinse între 1 și 12. În condiții alcaline (pH 12), cele mai mici nanoparticule de SiO2 au prezentat valori ale potențialului zeta de până la -58,4 mV, indicând faptul că suspensiile analizate au fost stabile în acest mediu.
Cuvinte cheie
printare 3D a silicei, procedeul Stöber, stabilitatea suspensiilor, potențial zeta
KARTHIKEYAN SAMBANDHAM, BASKAR NEELAKANDAN, GANESAN MANICKAM, RAMKUMAR KATHALINGAM
Rezumat
Friction welding is an efficient and economical process of joining two similar or dissimilar metals among various welding processes. Now-a-days, the automobile and other industries are using dissimilar metals in a same working area to compensate the problems faced due to temperature and working atmosphere to enhance company’s economy. The material AA6351 and EN353 alloy steel have wide applications in aerospace & automobile industries, are joined with different input parameters like Heating Time (HT), Heating Pressure (HP), Upset Time (UT), Upset Pressure (UP) with constant rotation. These input parameters are ordered using L27 Taguchi Orthogonal Array (OA) to experiment the process. Friction welding is done in KUKA friction welding machine. After experimentation, the responses like temperature, hardness and axial shortening are measured. Using these responses, the optimization is carried out through Grey Relational Analysis (GRA) and the rankings are identified and tabulated to obtain the optimal solutions. Based on rankings, the optimal input parameters are concluded as 18 bar of Heating Pressure (HP), 7 sec of Heating Time (HT), 22 bar of Upset Pressure (UP) and 3 sec of Upset Time (UT). The Field Emission Scanning Electron Microscope (FESEM) analysis is also used to study the Inter-metallic compounds (IMCs).
Cuvinte cheie
Friction Welding, AA6351, EN353, Grey Relational Analysis, FESEM analysis
GUIZHEN WANG, LINGLONG ZHOU
Rezumat
This study explores the seismic reinforcement of coastal buildings through the innovative application of Shape Memory Alloys (SMAs). SMAs, a novel class of functional materials, exhibit unique properties like shape memory effect, superelasticity, and high damping performance, making them ideal for seismic applications. Recognizing the critical role of structural design in a buildings earthquake resistance, this research introduces an SMA-based damper specifically tailored for coastal structures, considering their unique stress profiles and disaster vulnerability. Through experimental and simulation methods, including MATLABs Simulink module, the study compares the seismic responses of conventional coastal building designs with those incorporating the SMA damper. The results reveal that the SMA dampers bilinear restoring force mechanism significantly enhances vibration suppression, offering a promising solution for seismic reinforcement in building construction. This investigation not only contributes to the understanding of SMA materials but also underscores their potential in structural earthquake resilience, marking a significant intersection of material science, engineering, and seismic technology.
Cuvinte cheie
Shape Memory Alloys (SMAs); Seismic Dampers; Coastal Building Reinforcement; Earthquake Resistant Structures; Superelastic Materials