LIMITATIONS OF SECONDARY SCHOOL STUDENTS IN SOLVING A TYPE OF TASK RELATING TO THE EQUATION OF A CIRCLE: AN INVESTIGATION IN VIETNAM

In Vietnam, secondary school students learn the equation of a circle in Grade 10. Based on how to present this equation in the textbook “Geometry 10” and types of task for students, we believe that some limitations happen to students when they solve problems related to the equation of a circle. This paper reports the investigation of 845 students from the Mekong Delta-Vietnam. The results show that our prediction is correct.  Article visualizations

SYNTHESIS OF COPPER-BASED NANOPARTICLE CATALYSTS BY DIFFERENT METHODS FOR TOTAL OXIDATION OF VOC

In this paper, the process of preparing 10 wt.% Cu/g-Al2O3 catalysts was studied by different methods. The changes in structure and texture of the catalysts were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR). The activities of catalyst were investigated completely oxidized VOC (toluene and n-butanol) on gas-phase reactions over the Cu/g-Al2O3 catalyst. The results were found that influence of the size of copper nanoparticles enhancing copper dispersion and selectivity of the catalyst prepared by non-thermal plasma (NTP) was superior to those obtained from the impregnation (WI) and deposition-precipitation (DP). The total oxidation of VOC to CO2 and H2O was achieved above 275oC. Compared to the WI and DP, the NTP method increased the oxidation efficiency by 15-30%

Deep Learning-Aided Multicarrier Systems

This paper proposes a deep learning (DL)-aided multicarrier (MC) system operating on fading channels, where both modulation and demodulation blocks are modeled by deep neural networks (DNNs), regarded as the encoder and decoder of an autoencoder (AE) architecture, respectively. Unlike existing AE-based systems, which incorporate domain knowledge of a channel equalizer to suppress the effects of wireless channels, the proposed scheme, termed as MC-AE, directly feeds the decoder with the channel state information and received signal, which are then processed in a fully data-driven manner. This new approach enables MC-AE to jointly learn the encoder and decoder to optimize the diversity and coding gains over fading channels. In particular, the block error rate of MC-AE is analyzed to show its higher performance gains than existing hand-crafted baselines, such as various recent index modulation-based MC schemes. We then extend MC-AE to multiuser scenarios, wherein the resultant system is termed as MU-MC-AE. Accordingly, two novel DNN structures for uplink and downlink MU-MC-AE transmissions are proposed, along with a novel cost function that ensures a fast training convergence and fairness among users. Finally, simulation results are provided to show the superiority of the proposed DL-based schemes over current baselines, in terms of both the error performance and receiver complexity

When Intervention Becomes Imperative: A Case Report of Spontaneous Vulvar Edema During Pregnancy

Spontaneous idiopathic vulvar edema during the second trimester is a rare condition. The approach to managing this condition involves relieving symptoms, identifying underlying causes, and implementing appropriate treatment. Managing such cases during pregnancy is challenging because of concerns for potential adverse fetal outcomes. Conservative management expects the condition to be relieved spontaneously postpartum, whereas invasive treatment offers a more rapid resolution. Treatment choices are controversial because each method has its pros and cons and influences the delivery process to a certain extent. Surgical drainage becomes a viable option when patients are not responsive to medications. We report a case of spontaneous massive vulvar edema in a 22-year-old primigravida in her 23rd week of pregnancy. After ruling out other notable causes of vulvar edema, we decided to intervene using an invasive procedure because she complained of progressive symptoms and discomfort. Subsequently, the edema subsided postprocedure, and the patient experienced successful labor with no complications. This report aims to alert clinicians that drainage attempts should be considered in pregnant patients with worsening symptoms

Chemical profiles and antibacterial activity of acetone extract of two Curcuma species from Vietnam

Curcuma thorelii Gagnep. and Curcuma cotuana Luu, Škorni?k. & H.?.Tr?n are the rare species only found in Southeast Asia. The present study was the first to explore the chemical compositions and antibacterial effects of the whole plant acetone extracts of these 2 species. Altogether 41 and 31 compounds have been identified in C. thorelii and C. cotuana extracts by gas chromatography/mass spectrometry. Accordingly, the C. thorelii extract contained (E)-labda-8(17),12-diene-15,16-dial (33.37%), vitamin E (12.33%), phytol (9.83%) as the major compounds while C. cotuana extract contained predominantly (E)-labda-8(17),12-diene-15,16-dial (14.58%), n-hexadecanoic acid (10.96%), 3,7,11,15-tetramethylhexadec-2-en-1-yl acetate (8.13%), ?-sitosterol (7.97%). In addition, results from disc diffusion assay have shown that C. thorelii acetone extract had inhibitory effects on 5 out of 10 pathogenic bacterial strains such as Bacillus cereus (ATCC 11778), Listeria monocytogenes (ATCC 19111), Staphylococcus aureus (ATCC 25923), S. aureus (ATCC 29213) and S. saprophyticus (BAA750) while C. cotuana acetone extract was found to be effective only against B. cereus. The obtained results showed that the acetone extracts of C. thorelii and C. cotuana possessed several valuable bioactive compounds as well as promising antibacterial activity, which place a good foundation for future pharmaceutical product development

TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

3D object retrieval is an important yet challenging task, which has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe that this task has the potential to drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from being fully solved. As such, we provide insights into potential areas for future research and improvements. We believe that we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies.Comment: arXiv admin note: text overlap with arXiv:2304.0573

HMU fluorinze mouthwash enhances enamel remineralization: An in vitro study

BACKGROUND: Fluoride therapy has long been used extensively to prevent dental caries. Fluoride appears in variety of dental care products such as mouthrinse, dentifrice, gel, etc. HMU fluorinze is the first mouthwash containing fluoride in Vietnam. AIM: This research was conducted to evaluate the efficacy of HMU Fluorinze mouthwash on remineralizing enamel in laboratory conditions. METHODS: 20 third molars teeth were cleaned and covered with nail polish , except for a 3x3 mm square on their buccal surfaces. These teeth went through two steps: demineralization using Coke and remineralization for 20 days: 1) using standard calcifying solution (control group) and 2) using standard calcifying solution + HMU Fluorinze mouthwash 2 times/day (experimental group). The mineralization index of enamel structure after demineralization and remineralization was assessed by DIAGNOdent pen 2190. RESULTS: The mineralization indexes of the control group and experimental group at baseline were 3.65 ± 0.76 and 3.35 ± 0.64, after demineralization were in turn of 21.78 ± 4.48 and 20.25 ± 2.26; and after remineralization were 6.30 ± 1.03 and 3.90 ± 1.24. The different figures  between the two groups after remineralization shows statistical significance (p<0.01). Group B using HMU fluorinze mouthwash after 20 days did not differ from the original results (p = 0.272), in contrast with the control group (p<0.01). CONCLUSIONS: HMU fluorinze mouthwash has better mineralization effect than standard calcifying solution