Pressure controlling method for managed pressure drilling with supercritical carbon dioxide as the circulation fluid

Heat transfer along the wellbore was analyzed, and then a closed mathematical model, which fully couples the hydrostatic pressure, temperature, physical properties of CO2 and friction, was established to keep bottom-hole pressure constant during drilling process. Based on the pressure profile in wellbore achieved for a certain surface back pressure, a pressure controlling method for managed pressure drilling with supercritical carbon dioxide was presented. The influences of mass flow rate, well depth and inlet temperature on the annulus pressure profile and surface back pressure were investigated. The results show that, the pressure profile is almost in linear correlation with well depth in the annulus, which provides convenience for well control. The needed back pressure (applied by surface choke) decreases with increasing mass flow rate and decreasing well depth. The impact of inlet temperature on the annulus pressure profile, surface back pressure and flow friction is negligible. It also shows that the density of CO2 increases significantly and abruptly at a critical pressure. It is suggested that the storage pressure of CO2 in surface tank be larger than the critical pressure for a certain temperature. Key words: supercritical carbon dioxide drilling, managed pressure drilling, wellbore heat transfer, annulus pressure, surface back pressur

Generation of 48 fs, 1 GHz Fundamentally Mode-Locked Pulses Directly from an Yb-doped “Solid-State Fiber Laser”

We demonstrate a fundamentally mode-locked Yb-doped “solid-state fiber laser” with a repetition rate of 1 GHz and a pulse duration of 48 fs. The nonlinear-polarization-evolution (NPE) mode-locking of the “solid-state fiber laser” enables up to 286 mW of average power and a 26 nm spectrum bandwidth, which supports a 48 fs pulse duration. The laser self-starts and the central wavelength can be tuned from 1032.4 nm to 1035.6 nm. To the best of our knowledge, it is the shortest pulse duration directly obtained by GHz fundamentally mode-locked Yb-fiber lasers

The cascade influence of grain trade shocks on countries in the context of the Russia-Ukraine conflict

Abstract The Russia-Ukraine conflict has severely impacted global food security. This may increase the risk of supply chain disruption in low-income countries that rely heavily on grain imports. This study used production and trade data for wheat, barley and maize from 1995 to 2021 to construct longitudinal trade networks. On this basis, a cascading failure network model of shock propagation was used to identify the direct or indirect dependence of other countries on grain exported from Russia and Ukraine and the impact caused by trade shocks. The results revealed that the interruption of grain exports from Russia and Ukraine has resulted in an increasing impact on the global grain trade year by year and that the wheat trade is the most vulnerable to shock propagation, but it is also the most resilient. Russia and Ukraine interrupt exports of grain, causing more than 50% reduction in direct imports to 30 countries, including Eritrea, Seychelles, Kazakhstan and Mongolia. A shock propagation model that considers indirect dependence yields divergent results, with lower middle income (LM) countries in North Africa, Southeast Asia and West Asia facing supply shocks from reduced imports because they are unable to fully exploit the trade channels to balance grain supply and demand. Under the COVID-19 pandemic, this indirect dependence on imports is more prominent. It is worth noting that Eastern and Southern European countries often act as intermediaries to spread shocks during cascading failures. In the process of shock propagation, the main suppliers of grain include the United States, Canada, France, Argentina and Brazil. After the outbreak of COVID-19, the import demand faced by Australia increased significantly. We also examined how nodal characteristics relate to shock propagation dynamics and country vulnerability, finding that high import diversity, low import dependence and regional characteristics are effective in buffering countries from supply shocks. This study contributes to our understanding of the external supply risks for grain arising from the Russia-Ukraine conflict in a pandemic context, highlights the issue of accessibility in food security and provides trade policy recommendations to mitigate national vulnerability to food insecurity, thereby creating a resilient food trade system

Gastric Glomus Tumor: A Clinicopathologic and Immunohistochemical Study of 21 Cases

Gastric glomus tumors (GGTs) are rare mesenchymal tumors. Most glomus tumors occur in the distal parts of the extremities. Here, we retrospectively analyzed the features of GGTs from two institutions. The histologic and clinical findings of all GGT cases from 2009 to 2018 were reviewed. The most common location was the antrum, the mean age of patients was 49.3 years, and the mean tumor size was 2.1 cm. Microscopically, small, round cell nodules surrounded the expansion of blood vessels in a nest pattern. Immunohistochemical assays for vimentin and smooth muscle actin (SMA) were positive, and assays for H-caldesmon and calponin were partially positive. GGT is rare and easily misdiagnosed before operation. However, immunohistochemistry is useful for the differential diagnosis. The majority of GGTs are benign, and local surgery achieving complete resection is the most effective treatment method

Mechanisms and therapeutic prospects of mesenchymal stem cells-derived exosomes for tendinopathy

Abstract Tendinopathy is a debilitating and crippling syndrome resulting from the degeneration of tendon tissue, leading to loss of mechanical properties and function, and eventual tendon rupture. Unfortunately, there is currently no treatment for tendinopathy that can prevent or delay its progression. Exosomes are small extracellular vesicles that transport bioactive substances produced by cells, such as proteins, lipids, mRNAs, non-coding RNAs, and DNA. They can generate by mesenchymal stem cells (MSCs) throughout the body and play a role in intercellular communication and regulation of homeostasis. Recent research suggests that MSCs-derived exosomes (MSCs-exos) may serve as useful therapeutic candidates for promoting tendon healing. This review focuses on the function and mechanisms of MSCs-exos in tendinopathy treatment and discusses their potential application for treating this condition

Association between induced abortion and suicidal ideation among unmarried female migrant workers in three metropolitan cities in China: a cross-sectional study

Abstract Background Despite reports of mental health issues, suicidality has not been closely examined among the migrant population. The association between induced abortion and suicidal ideation is unknown among unmarried female migrant workers of reproductive age in China. This study aims to examine induced abortion and suicidality among the Chinese migrant population. Methods We recruited 5115 unmarried female migrant workers during 2015 to 2016 from Shanghai, Beijing and Guangzhou, and collected demographic, psychosocial, reproductive and mental health information using structured questionnaires. We used logistic regression models to examine the association between lifetime induced abortion and suicidal ideation during the past year among the subjects. Results Overall, 8.2% of the subjects had suicidal ideation during the past year, and 15.5% of the subjects experienced induced abortion. Induced abortion was associated with nearly twice the odds of having past-year suicidal ideation (Odds ratio, OR = 1.89; 95% confidence interval, CI: 1.46, 2.44) after adjusting for age, education, years in the working place, tobacco use, alcohol consumption, daily internet use, attitude towards premarital pregnancy, multiple induced abortion, self-esteem, loneliness, depression, and anxiety disorders. The association was stronger in those aged > 25 (OR = 3.37, 95% CI = 2.16, 5.28), with > 5 years of stay in the working place (OR = 2.98, 95% CI = 2.02, 4.39), the non-anxiety group (OR = 2.28, 95% CI = 1.74, 3.00), and the non-depression group (OR = 2.94, 95% CI = 2.08, 4.15). Conclusions Induced abortion was associated with increased odds for suicidal ideation among the unmarried female migrant workers in urban cities in China. More attention should be paid to the mental health of the population

Study on properties of recycled mixed polyester/nylon/spandex modified by hydrogenated petroleum resin

In order to improve the utilization value of recycled materials, the study considers recycled materials such as polyester/nylon/spandex as raw materials. Using polyester/polyamide/spandex as raw materials, the recycled polyester/polyamide/spandex mixed materials were first pretreated to obtain the pretreated mixed materials. Then, the pretreated mixed materials were evenly mixed with hydrogenated petroleum resin. The composite materials were prepared through extrusion and injection molding. By comparing the mechanical properties, the effects of different hydrogenated petroleum resins and their additives on the tensile strength, bending strength, impact strength, elongation at break, and bending modulus of the composites were investigated. And the microstructure of the fracture surface was characterized by scanning electron microscopy. The results showed that: (a) when the addition amount of hydrogenated C5 petroleum resin was 4.5%, the maximum impact strength and fracture elongation were 18.03 kJ/m2 and 15.92%, respectively. (b) The maximum tensile strength, bending strength, and bending modulus could reach 22.9, 38.72, and 2217.9 MPa, when the addition amount of hydrogenated C9 petroleum resin was 4.5, 29.5, and 39.5%, respectively

Comparative Effectiveness of Different Combinations of Treatment Interventions in Patients with Stroke at the Convalescence Stage Based on the Markov Decision Process

Objective. The objective of this study was to compare the effectiveness of different combinations of interventions in patients with stroke at the convalescence stage based on the electronic health records (EHRs) by using the Markov decision process (MDP) theory and explore the feasibility of the Markov model in the real-world study (RWS). Methods. Screening was conducted for patients with stroke at the convalescence stage who were admitted to the Third Affiliated Hospital of Zhejiang Chinese Medical University from January 2012 to January 2017 based on the EHRs. The relevant clinical data were extracted, and the appropriate conversion was made (state-action-reward) according to the Markov model. The transformed data were analysed and solved by the MDP to obtain the best interventions for patients with various stroke recovery periods. Results. 926 patients with stroke at the convalescence stage were initially selected. And according to the inclusion exclusion criteria, 854 patients were screened. Through the MDP, we obtained the following results: (1)when the patients with stroke at the convalescence stage have a medical history, but no complications, and mild neurological impairment, ≥66-year- and 18–45-year-old patients are advised to choose acupuncture treatment. 46–65-year-old patients are advised to choose rehabilitation treatment. When patients with moderate to severe neurological impairment, patients are advised to choose rehabilitation, Chinese herbal decoction, and acupuncture combined therapy. (2) Without complications or medical history, patients who are ≥ 66 years old are recommended to choose rehabilitation treatment when the nerve function impairment is mild; rehabilitation and acupuncture treatment are recommended when moderate and severe injuries are caused. (3) The combination of rehabilitation, Chinese herbal decoction, and acupuncture treatment is recommended for patients with phlegm and blood stasis. Acupuncture treatment is recommended for patients with mild impairment of nerve function in qi deficiency and blood stasis type. Rehabilitation, Chinese herbal decoction, and acupuncture treatment are recommended for moderate-severe injuries. Conclusions. The MDP makes it possible to study the effectiveness of various treatment methods in stroke patients who are at the convalescence stage. Further exploratory studies using MDP theory in other areas in which complex interventions are common would be worthwhile

Sexual compulsivity and its relationship with condomless sex among unmarried female migrant workers in Shanghai, China: a cross-sectional study

Abstract Background Individuals with high sexual compulsivity are preoccupied with their sexual desire to such an extent that it interferes with their normal daily life and can inhibit self-control. Previous studies have found a close association between sexual compulsivity and condomless sex among different populations; however, no studies have investigated this among unmarried female migrant workers in China. This study aimed to validate the Sexual Compulsivity Scale (SCS) for appropriate use and examine the association between sexual compulsivity and condomless sex in this target population. Methods In 2015, we recruited 1325 unmarried female migrant workers in Shanghai, China. Information about sociodemographics, sexual compulsivity, and condomless sex were collected using a structured questionnaire. Exploratory factor analysis and reliability analysis were performed to validate the Chinese version of the SCS. Multiple logistic regression analyses were used to examine the association between sexual compulsivity and condomless sex. Results The prevalence of condomless sex in the previous 6 months was 66.8% among all participants. The SCS was proven internally consistent for the overall scale (Cronbach’s α = 0.89), and two factors, Social Disruptiveness (Cronbach’s α = 0.87) and Perceived Self-Control (Cronbach’s α = 0.84), were extracted. With mean total score of 18.25 (standard deviation = 4.94) after adjusting for significant sociodemographic factors, the SCS total scores (adjusted odds ratio [AOR] = 1.04, 95% confidence interval [CI] = 1.02–1.07) and two subscale scores (AOR = 1.07, 95% CI = 1.02–1.13; AOR = 1.06, 95% CI = 1.02–1.10) were all related to inconsistent condom use with partners in the previous 6 months. Conclusions The Chinese version of the SCS was found to be well adaptable for use among unmarried Chinese female migrant workers and a potential predictor for condomless sex. In addition to safe sex interventions, counselling on managing sexually compulsivity should also be provided in this population