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Introduction: Premature ejaculation (PE) is a prevalent sexual dysfunction in men that greatly affects their quality of life. In PE, the duration of sexual performance is considered an important aspect. However, a self‐estimated value of intravaginal ejaculation latency time (perceived IELT, PIELT) as a criterion for diagnosis has not been specified. Aim: This study aimed to determine the validity and a threshold value for PIELT in PE diagnosis. Method: In our cross‐sectional study, we recruited 550 men from March 2019 to January 2020 and interviewed them regarding their general demographic characteristics, sexual habits, PIELT and completed a premature ejaculation diagnostic tool (PEDT) questionnaire. Eventually, a combination of a clinical diagnosis and PEDT score was used, in which those with PEDT ≥ 11 and diagnosed with possible PE were assigned to the final PE(+) group; those with PEDT score ≤ 8 and diagnosed with no PE were included in the final PE(−) group. Results: Men PE(−) had more frequent sexual intercourse (9.74 ± 5.38 vs. 6.69 ± 5.38 episodes per month, p < 0.001) and had higher marriage rate (72.7% vs. 60.4%, p = 0.002) than PE(+) patients. No significant difference was noted regarding age, smoking habit, age of first sexual experience, and number of sexual partners between the two groups. The mean PIELT of control subjects and PE(+) patients were 11.69 ± 6.83 min and 2.01 ± 1.21 min, respectively. On receiver operating characteristic curve analysis, the cut‐off value of PIELT of 3.75 min can be used to distinguish PE men (area under the curve = 0.982, sensitivity/specificity = 0.961/0.909), which means that men with a PIELT ≤ 3.5 min is suggestive of PE. Conclusion: The impact of PE is dramatic both from a social and a personal perspective. PE(+) patients married significantly less and have significantly lower sexual activity compared to a PE(‐) population. Furthermore, a PIELT of ≤ 3.5 min predicts PE demonstrating the need to revise its taxonomy and definition. [ABSTRACT FROM AUTHOR]

Melting temperature is a fundamental material property and is defined as the temperature at which the solid and liquid phases have the same free energy. However, there is no systematic study employing atomic simulations to calculate melting temperature using this definition. Here, molecular dynamics simulations and nonequilibrium thermodynamic integration methods are combined to calculate the melting temperature of Al and Cu. Results show that to accurately obtain the melting temperature, the model size should be considered carefully because the free energies of both solid and liquid phases are inversely proportional to the model size, causing a model size dependence on the calculated melting temperature. In addition, the melting temperature for various (semi‐) empirical potential models for Al and Cu is calculated and verified against experimental values to provide guidelines for the choice of potential models for simulation‐based problems relevant to the solid–liquid phase transformation. [ABSTRACT FROM AUTHOR]

Free energies of a solid surface and a solid–liquid interface play significant roles in thermodynamics. Due to the limited availability of experimental data, computational methods offer effective alternatives for calculating these properties. This study adopts advanced frameworks of the logarithmic mean force dynamics method to present an enhanced sampling approach for the calculation of the free energy at different temperatures. To achieve this, the free energy profile is constructed along with a pre‐established collective variable within the melting transition and cleavage processes. The values of the solid surface and solid–liquid interface free energies are then extrapolated from the excess free energy related to the formation and persistence of the solid surface or the solid–liquid interface. Furthermore, this methodology is employed to calculate the temperature dependence of the free energy measurements for the (100) and (110) surfaces and interfaces of Cu. It is shown that this methodology is robust and readily applicable in contemporary models of atomic interactions and various systems. [ABSTRACT FROM AUTHOR]

The Poisson's ratio of two-dimensional materials such as graphene can be tailored by surface hydrogenation. The density and distribution of hydrogenation may significantly affect the Poisson's ratio of the graphene structure. Therefore, optimization of the distribution of hydrogenation is useful to achieve the structure with a targeted Poisson's ratio. For this purpose, we developed an inverse design algorithm based on machine learning using the XGBoost method to reveal the relationship between the Poisson's ratio and distribution of hydrogenation. Based on this relationship, we can optimize the hydrogenated graphene structure to have a low Poisson's ratio. Instead of performing molecular dynamic simulations for all possible structures, we could find the optimal structures using the search algorithm and save significant computational resources. This algorithm could successfully discover structures with low Poisson's ratios around −0.5 after only 1600 simulations in a large design space of approximately 5.2 × 106 possible configurations. Moreover, the optimal structures were found to exhibit excellent flexibility under compression of around −65% without failure and can be used in many applications such as flexible strain sensors. Our results demonstrate the applicability of machine learning to the efficient development of new metamaterials with desired properties. [ABSTRACT FROM AUTHOR]

With its excellent mechanical and thermal properties, bilayer graphane is a promising material for realizing future nanoelectromechanical systems. In this study, we focus on the auxetic behavior of bilayer graphane under external loading along various directions through atomistic simulations. We numerically and theoretically reveal the mechanism of the auxeticity in terms of intrinsic interactions between carbon atoms by constructing bilayer graphane. Given that the origin of the auxeticity is intrinsic rather than extrinsic, the work provides a novel technique to control the dimensions of nanoscale bilayer graphane by simply changing the external conditions without the requirement of complex structural design of the material. [ABSTRACT FROM AUTHOR]

Background: Penis size is a highly sensitive topic, which has often raised concerns associated with human masculinity and male sexual health. Although data regarding penile dimensions have been published worldwide, little is known about these measurements in South‐East Asian countries. Objective: This study aimed to provide the reference range in penile length, circumference, and diameter of Vietnamese men and their variations among men with erectile dysfunction and other diseases. Materials and Methods: Information about flaccid length, stretched length, mid‐shaft circumference, and glans diameter from the health records of 14,597 men attending the Andrology Consultation was collected. These men were classified into three groups being regular reproductive health screening group, sexual dysfunction group, and other disease groups. Results: We found that penile dimensions follow a non‐parametric distribution, as tested by Kolmogorov‐Smirnov test. The median values are 9.03 cm for flaccid length, 14.67 cm for stretched length, 8.39 cm for mid‐shaft circumference, and 2.86 cm for unaroused glans diameter. Length and girth of the penis also changed among the different groups, especially in flaccid state; specifically, men with erectile dysfunction had a greater value in all penile dimensions except for change ratio compared with other groups. Circumcision, which rarely occurs in Vietnam, was associated with a 2 mm reduced penis length. Discussion: Findings on correlations between penile dimensions and somatometric parameters from previous studies are questionable and some measurements, such as glans dimension, have not been thoroughly investigated so far. Nevertheless, penile dimensions provide useful insight concerning conditions affecting sexual development and might be a valuable parameter in the assessment of erectile dysfunction. Conclusion: Results of this study provide informative materials for the assessment of penile size, including reference values drawn from a large sample of Vietnamese men that can be useful in clinical practice and sexual health education. [ABSTRACT FROM AUTHOR]

Testicular size is an important parameter to investigate male reproductive and sexual functions. However, diagnosis and treatments are hindered by the lack of country‐specific standard values for testicular volume. We conducted the present retrospective chart review study on 24,440 men who sought consultation at Andrology and Sexual Medicine—Hanoi Medical University Hospital to provide a reference range of testicular volume and to determine the correlations between testicular volume, age and hormonal profiles. These men were classified into groups being healthy fathers, hypogonadal men, unexplained infertile men, men with unknown fertility, testicular pathologies and other andrological condition groups. Hypogonadal men and unexplained infertile men had significantly smaller testicular sizes compared with healthy fathers. The mean value of testicular volume of healthy subjects was 13.64 ± 3.44 ml (left testis: 13.94 ± 3.72 ml; right testis: 13.34 ± 3.61 ml; p < 0.001). Testicular size of Vietnamese men was negatively correlated with LH and FSH (Rho = −0.16 and −0.33, p < 0.001) and positively correlated with testosterone after adjusting for confounding factors. Testicular volume was independent of the subject's age and smoking habits. [ABSTRACT FROM AUTHOR]

The definition and diagnosis of functional hypogonadism (FH) remains challenging due to the nonspecific nature of symptoms and the inconsistency in normal testosterone thresholds. We conducted this single-center cross-sectional study on medical records of men aged 18 and above undergoing annual health check-ups to evaluate the correlation of age and metabolic components with testosterone. A total of 5,374 healthy men were included in the analysis. Total testosterone levels peaked at 18 years and gradually declined to age 40, followed by a mild increase. Based on the American Urology Association guideline, age-specific cutoffs for low testosterone were 14.61 nmol/l, 12.74 nmol/l, 12.70 nmol/l, and 13.98 nmol/l for those under 30, 30-40, 40-50, and over 50 years old respectively. Triglyceride - Glucose index showed a consistent negative correlation with testosterone across all age groups. In conclusion, testosterone levels demonstrated an age-related decline in early adulthood but a potential increase thereafter among healthy Vietnamese men. Metabolic components, rather than aging, had a consistent negative correlation with testosterone. Age-specific cutoffs for low testosterone may improve the detection of functional hypogonadism.

Purpose: Hypogonadism is associated with a wide range of physical and psychological symptoms that can affect the overall health of men. However, in a developing country, there are several imposing challenges in the diagnosis and treatment of hypogonadism, including a lack of awareness and understanding of the condition among healthcare providers and patients, limited resources and the high cost of treatment. This review aimed to examine the potential benefits and risks of testosterone replacement therapy (TRT) and provides a perspective of a developing country on the topic., Materials and Methods: A comprehensive literature review was conducted to gather relevant information on the impact of testosterone deficiency on ageing males and the effectiveness of TRT for treating hypogonadism. Published peer-reviewed articles were analyzed to evaluate the benefits and risks of TRT. Additionally, the unique challenges faced in the diagnosis and treatment of hypogonadism in a developing country were considered., Results: Testosterone replacement therapy has been shown to be an effective treatment for hypogonadism, particularly in symptomatic men with low testosterone levels. It offers potential benefits such as improvements in symptoms and overall quality of life. However, there are associated risks and side effects that need to be considered. In a developing country, challenges such as limited awareness and understanding of hypogonadism, resource constraints, and high treatment costs pose additional barriers to accessing TRT and comprehensive care., Conclusion: In conclusion, TRT holds promise as a treatment for hypogonadism, but its implementation and accessibility face significant challenges in a developing country. Addressing these challenges, including raising awareness, allocating resources, and finding cost-effective solutions, is crucial for ensuring that men with hypogonadism in such settings receive appropriate diagnosis and treatment. Further research and efforts are needed to improve the management of hypogonadism in developing countries and optimize the potential benefits of TRT for affected individuals.

Testicular size is an important parameter to investigate male reproductive and sexual functions. However, diagnosis and treatments are hindered by the lack of country-specific standard values for testicular volume. We conducted the present retrospective chart review study on 24,440 men who sought consultation at Andrology and Sexual Medicine-Hanoi Medical University Hospital to provide a reference range of testicular volume and to determine the correlations between testicular volume, age and hormonal profiles. These men were classified into groups being healthy fathers, hypogonadal men, unexplained infertile men, men with unknown fertility, testicular pathologies and other andrological condition groups. Hypogonadal men and unexplained infertile men had significantly smaller testicular sizes compared with healthy fathers. The mean value of testicular volume of healthy subjects was 13.64 ± 3.44 ml (left testis: 13.94 ± 3.72 ml; right testis: 13.34 ± 3.61 ml; p < 0.001). Testicular size of Vietnamese men was negatively correlated with LH and FSH (Rho = -0.16 and -0.33, p < 0.001) and positively correlated with testosterone after adjusting for confounding factors. Testicular volume was independent of the subject's age and smoking habits., (© 2021 Wiley-VCH GmbH.)