http://repository.enu.kz/handle/enu/15588 2026-04-03T23:18:15Z 2026-04-03T23:18:15Z Suchikova, Yana Kovachov, Sergii Bohdanov, Ihor Konuhova, Marina Zhydachevskyy, Yaroslav Kumarbekov, Kuat Pankratov, Vladimir Popov, Anatoli I. http://repository.enu.kz/handle/enu/29758 2026-03-04T19:04:35Z 2024-01-01T00:00:00Z

Wet Chemical Synthesis of AlxGa1−xAs Nanostructures: Investigation of Properties and Growth Mechanisms Suchikova, Yana; Kovachov, Sergii; Bohdanov, Ihor; Konuhova, Marina; Zhydachevskyy, Yaroslav; Kumarbekov, Kuat; Pankratov, Vladimir; Popov, Anatoli I. This study focuses on the wet chemical synthesis of AlxGa1−xAs nanostructures, highlighting how different deposition conditions affect the film morphology and material properties. Electrochemical etching was used to texture GaAs substrates, enhancing mechanical adhesion and chemical bonding. Various deposition regimes, including voltage switching, gradual voltage increase, and pulsed voltage, were applied to explore their impact on the film growth mechanisms. SEM analysis revealed distinct morphologies, EDX confirmed variations in aluminum content, Raman spectroscopy detected structural disorders, and XRD analysis demonstrated peak position shifts. The findings emphasize the versatility and cost-effectiveness of wet electrochemical methods for fabricating high-quality AlxGa1−xAs films with tailored properties, showing potential for optoelectronic devices, high-efficiency solar cells, and other advanced semiconductor applications.

2024-01-01T00:00:00Z Callaghan, Peter J. Caffrey, David Zhussupbekov, Kuanysh Berman, Samuel Zhussupbekova, Ainur Smith, Christopher M. Shvets, Igor V. http://repository.enu.kz/handle/enu/29757 2026-03-04T19:01:17Z 2024-01-01T00:00:00Z

Variation in the Bandgap of Amorphous Zinc Tin Oxide: Investigating the Thickness Dependence via In Situ STS Callaghan, Peter J.; Caffrey, David; Zhussupbekov, Kuanysh; Berman, Samuel; Zhussupbekova, Ainur; Smith, Christopher M.; Shvets, Igor V. Amorphous transparent conducting oxides (aTCOs) have seen substantial interest in recent years due to the significant benefits that they can bring to transparent electronic devices. One such material of promise is amorphous ZnxSn1−xOy (a-ZTO). a-ZTO possesses many attractive properties for a TCO such as high transparency in the visible range, tunable charge carrier concentration, electron mobility, and only being composed of common and abundant elements. In this work, we employ a combination of UV−vis spectrophotometry, X-ray photoemission spectroscopy, and in situ scanning tunneling spectroscopy to investigate a 0.33 eV blue shift in the optical bandgap of a-ZTO, which we conclude to be due to quantum confinement effects.

2024-01-01T00:00:00Z Issatayev, Nurbolat Abdumutaliyeva, Diana Tashenov, Yerbolat Yeskozha, Dossym Seipiyev, Adilkhan Bakenov, Zhumabay Nurpeissova, Arailym http://repository.enu.kz/handle/enu/29756 2026-03-04T19:01:34Z 2024-01-01T00:00:00Z

Three-dimensional carbon coated and high mass-loaded NiO@Ni foam anode with high specific capacity for lithium ion batteries Issatayev, Nurbolat; Abdumutaliyeva, Diana; Tashenov, Yerbolat; Yeskozha, Dossym; Seipiyev, Adilkhan; Bakenov, Zhumabay; Nurpeissova, Arailym Nickel oxide (NiO) is known for its remarkable theoretical specific capacity, making it a highly appealing option for electrode materials in electrochemical energy storage applications. Nevertheless, its practical use is limited by poor electrochemical performance and complicated electrode fabrication processes. To address these issues, we propose a new anode design comprising an intermediate NiO nanoarray layer and a carbon coating layer grown directly on a three-dimensional (3D) conductive nickel foam substrate, designated as C@NiO@Ni foam. This anode with a high NiO mass loading of 5–6 mg cm−2 is fabricated by a two-step process: thermal oxidation of the nickel foam, followed by carbon coating. The 3D architecture, with its large surface area, significantly enhances the contact between the electrode and electrolyte, thereby shortening the Li-ion diffusion pathway. Additionally, the carbon layer plays a crucial role in accommodating the volume changes of NiO during cycling, preventing the detachment of NiO from the Ni foam substrate, and enhancing the electronic conductivity of the C@NiO@Ni foam. The resulting porous C@NiO@Ni anode was thoroughly analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). When used as an anode material for lithium-ion batteries (LIBs), this anode showcased an impressive reversible capacity of around 678 mA h g−1 at 0.1C after 100 cycles. Furthermore, it demonstrated excellent electrochemical performance at a high current, sustaining a specific capacity of 387 mA h g−1 at 1C after 100 cycles.

2024-01-01T00:00:00Z Begimbetova, Dinara Burska, Agata N. Baltabekova, Aidana Kussainova, Assiya Kukanova, Assiya Fazyl, Fatima Ibragimova, Milana Manekenova, Kenzhekyz Makishev, Abay Bersimbaev, Rakhmetkazhi I. Sarbassov, Dos D. http://repository.enu.kz/handle/enu/29755 2026-03-04T19:01:58Z 2024-01-01T00:00:00Z

The Vitamin C Enantiomers Possess a Comparable Potency in the Induction of Oxidative Stress in Cancer Cells but Differ in Their Toxicity Begimbetova, Dinara; Burska, Agata N.; Baltabekova, Aidana; Kussainova, Assiya; Kukanova, Assiya; Fazyl, Fatima; Ibragimova, Milana; Manekenova, Kenzhekyz; Makishev, Abay; Bersimbaev, Rakhmetkazhi I.; Sarbassov, Dos D. The use of vitamin C (VC) in high doses demonstrates a potent tumor suppressive effect by mediating a glucose-dependent oxidative stress in Kirsten rat sarcoma (KRAS) mutant cancer cells. VC with arsenic trioxide (ATO) is a promising drug combination that might lead to the development of effective cancer therapeutics. Considering that a tumor suppressive effect of VC requires its highdose administration, it is of interest to examine the toxicity of two enantiomers of VC (enantiomer d-optical isomer D-VC and natural l-optical isomer L-VC) in vitro and in vivo. We show that the combinations of L-VC with ATO and D-VC with ATO induced a similar cytotoxic oxidative stress in KrasG12D-expressing mutant cancer cells as indicated by a substantial increase in reactive oxidative species (ROS) production and depolarization of mitochondria. To examine the L-VC and D-VC toxicity effects, we administered high doses of D-VC and L-VC to CD1 mice and carried out an evaluation of their toxic effects. The daily injections of L-VC at a dose of 9.2 g/kg for 18 days were lethal to mice, while 80% of mice remained alive following the similar high-dose administration of D-VC. Following the drug injection courses and histopathological studies, we determined that a natural form of VC (L-VC) is more harmful and toxic to mice when compared to the effects caused by the similar doses of D-VC. Thus, our study indicates that the two enantiomers of VC have a similar potency in the induction of oxidative stress in cancer cells, but D-VC has a distinctive lower toxicity in mice compared to L-VC. While the mechanism of a distinctive toxicity between D-VC and L-VC is yet to be defined, our finding marks D-VC as a more preferable option compared to its natural enantiomer L-VC in clinical settings.

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