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Key clinical message In in vitro fertilization (IVF), laser offers several advantages. In this study, we employed laser to eliminate the zona pellucida of a contaminated embryo. This approach helps to rescue embryo with bacterial contamination, and improve embryo‐endometrium interaction. Abstract To present a case report on the removal of a contaminated zona pellucida from an embryo of patient with a history of recurrent implantation failure (RIF), which was followed by a successful live birth. We present the case of a 34‐year‐old patient with a history of 3 years of infertility who underwent in vitro fertilization. During the culture process, the embryos became contaminated, leading to three failed implantations. Despite the aneuploidy of the embryo and the implementation of a washing technique, the contamination persisted. In the final attempt, the contaminated zona pellucida was successfully removed using laser, followed by embryo transfer, resulting in a live birth. We provided detailed clinical information, including patient demographics, infertility history, ovarian response, evidence of bacterial contamination, embryo development, treatment protocols, and outcomes. Laser excision of the zona pellucida is a safe and effective method for addressing bacterial infection in embryos.

Objective: To compare embryonic development, ploidy status and clinical outcomes between fresh and frozen-thawed oocytes. Methods: This retrospective cohort study evaluated 83 fertilization cycles including both fresh and frozen oocytes from 79 patients at the HP Fertility Center of Hai Phong International Hospital of Obstetrics and Pediatrics in Vietnam. The patient underwent several ovarian stimulation cycles to accumulate a certain number of oocytes that would be vitrified. In the last oocyte retrieval, all patient's oocytes including both frozen and fresh would be fertilized. The outcomes included the rates of oocyte survival, cleavage embryo, blastocyst, ploidy status, pregnancy, biochemical pregnancy and clinical pregnancy. Results: The oocyte survival rate after thawing was 96.5%. No statistically significant difference was found when comparing fresh and frozen oocytes regarding fertilization rate (78.1% vs. 75.5%, P=0.461), usable cleavage embryo rate (86.9% vs. 87.2%, P=0.916) but usable blastocyst rate was found higher statistically in the frozen oocyte group (44.4% vs. 54.0%, P=0.049). The percentages of euploid, aneuploid and mosaic embryos between the fresh group and the vitrified group had no significant differences (33.8% vs. 31.6%, P=0.682; 51.0% vs. 54.2%, P=0.569; 15.2% vs. 12.4%, P=0.787; respectively). The rates of pregnancy, biochemical pregnancy and clinical pregnancy had no statistical difference (68.8% vs. 64.8%, P=0.764; 12.5% vs. 3.6%, P=0.258; 37.5% vs. 46.4%, P=0.565). 17 Mature oocytes are the minimum to have at least one euploid embryo. Conclusions: Oocyte vitrification does not affect embryonic, genetic and clinical results. The number of mature oocytes should be considered for fertilization in some cases.

This study focused on testing the existence of an apartment price bubble in Hanoi (Vietnam) and on determining the factors that affected it in the period between 2010 and 2021. Using the fundamental factor approach, the authors applied VAR regression using time series data. Specifically, we used the ADF unit test to test the stationarity of the variables based on the following criteria: AIC (Akaike information criterion); LR (likelihood ratio); FPE (final prediction error); HQ (Hanan–Quinn information criterion); and Schwarz (SC) to find the optimal lag (Lag) for the model. We also applied the Granger causality test to determine the correlation between the economic variables that appeared in the model with the PR index. We present the results of the research model through the push–response function and the variance decomposition to consider and evaluate the impact of the PR index shock on itself and the other variables. The literature in this field includes many studies that are similar to this one; however, no research has been conducted that has focused on analysing whether variables, such as per capita income and the urbanisation rate, influence the formation of real estate bubbles. This focus is especially relevant in Hanoi, which is an important part of the Vietnamese real estate market. Through this study, we aimed to fill this gap and to contribute to the references on the Hanoi real estate market and its influencing factors.

Biochemical oxygen demand (BOD) and pH are two important parameters in environmental analysis that allow the assessment of water quality. Although the long-term determination of BOD and pH can provide more useful information about the wastewater characteristics, present commercial BOD devices do not usually meet this demand. This research has successfully developed a novel BOD/pH device based on the respirometric principle, which can simultaneously and continuously monitor both BOD and pH of wastewater for about 20 days. The performance of the proposed device is evaluated in the laboratory by comparison to that of a commercial device (BOD Trak II, HACH). This solution not only follows the variation of BOD and pH over a long period of time, but also shows low cost and high potential for a wide variety of applications in Vietnam.

A method for producing ferulic acid by ultrasound-assisted, homogeneous, base-catalyzed hydrolysis of γ-oryzanol was developed. Experiments were conducted using various reaction temperatures and ratios of γ-oryzanol to base catalyst in both homogeneous and heterogeneous systems. The reaction performed without ultrasound under the homogeneous conditions of potassium hydroxide/γ-oryzanol ratio (wt/wt) 20 : 1 and 75°C gave a ferulic acid yield of 83.3% in 3 h. Acceleration of the homogeneous reaction using ultrasound irradiation at 20 (horn type) and 200 kHz (planar type) was explored by evaluating the kinetic parameters. At 30°C, the ratios of ultrasonic irradiation at low (20 kHz, 50 W) and high (200 kHz, 50 W) frequencies versus those of the heating method increased by 2.0- and 1.4-fold in comparison with those at 60°C, respectively. The contribution of ultrasonic irradiation (50 W) to the hydrolysis reaction decreased with increase of temperature. However, irradiation at 20 kHz and a power of 180 W gave a 94% ferulic acid yield at 60°C in 3 h. These results indicate that the use of low frequency (horn type and high-power irradiation) enabled yields higher than 90% to be obtained.

In this work, we study the influence of the substitution Si for Ni for the magnetic properties of LaNi5-xSix (x = 0-0.5) alloys. The structure of the alloy was tested by X-ray diffraction (XRD) measurements. The magnetic properties of the samples were carried out using a vibrating sample magnetometer (VSM) system. The results showed that when Ni was substituted for Si in alloys and after hydrogen absorption, LaNi5-xSix alloys retained their CaCu5 structure. The susceptibility (χ) of the alloys decreased when substituting Ni by Si increased. The original bulk samples showed a Pauli paramagnetism state after hydrogen absorption transformed into a superparamagnetic state. The results obtained showed that although measurements of magnetic characteristics are relatively simple, quantitative information about the microscopic processes occurring in the material was used as the negative electrode in Ni-MH rechargeable battery.

Tetramethylsilane, alone and in combination with inert gases are widely used in various material processing. The electron transport coefficients in binary mixtures tetramethylsilane gas with buffer gases such as Kr, Xe, He, and Ne gases, therefore, was firstly calculated and analyzed by a two-term approximation of the Boltzmann equation in the E/N (ratio of the electric field E to the neutral number density) range of 0.1-1000 Td (Townsend). These results can be considered to use in many industrial applications depending on particular application of gas, especially on plasma polymerization and plasma enhanced chemical vapour deposition.