MXene and AgNW based flexible transparent conductive films with sandwich structure for high-performance EMI shielding and electrical heaters

With the popularization of 5G technology and the development of science and technology, flexible and transparent conductive films (TCF) are increasingly used in the preparation of optoelectronic devices such as electromagnetic shielding devices, transparent flexible heaters, and solar cells. Silver nanowires (AgNW) are considered the best material for replacing indium tin oxide to prepare TCFs due to their excellent comprehensive properties. However, the loose overlap between AgNWs is a significant reason for the high resistance. This article investigates a sandwich structured conductive network composed of AgNW and Ti3C2Tx MXene for high-performance EMI shielding and transparent electrical heaters. Polyethylene pyrrolidone (PVP) solution was used to hydrophilic modify PET substrate, and then MXene, AgNW, and MXene were assembled layer by layer using spin coating method to form a TCF with a sandwich structure. One-dimensional AgNW is used to provide electron transfer channels and improve light penetration, while two-dimensional MXene nanosheets are used for welding AgNWs and adding additional conductive channels. The flexible TCF has excellent transmittance (85.1 % at 550 nm) and EMI shielding efficiency (27.1 dB). At the voltage of 5 V, the TCF used as a heater can reach 85.6 °C. This work offers an innovative approach to creating TCFs for the future generation.

Caffeic-Acid-Functionalized MWCNTs and PEDOT:PSS Formed Composite Flexible Films with "Reinforced Concrete" Structure for Electrical Heating and EMI Shielding

Nowadays, flexible multifunctional composites are attracting much attention and are practically being used in various emerging electronic devices. However, most composites suffer from the disadvantages of high loadings of conductive fillers, complicated preparation processes, and low energy conversion efficiency. In this article, Caffeic acid-modified multiwalled carbon nanotubes (C-MWCNTs)/poly(3,4-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS)/polyimide (PI) composite films (CPFs) were prepared using a simple layer-by-layer deposition method. The "reinforced concrete" structure of the C-MWCNTs/PEDOT:PSS layer ensures high electrical conductivity of the film, while the PI layer provides excellent mechanical properties (72.69 MPa). The composite film exhibits excellent electrothermal response and thermal stability up to approximately 125 °C at 5 V. In addition, the good conductivity of the film provides its electromagnetic shielding effectiveness (32.69 dB). With these advantages, we expect that flexible CPFs will be widely utilized in wearable devices, electromagnetic interference (EMI) shielding applications, and thermal management of personal or electronic devices.

Embedded ultra-high stability flexible transparent conductive films based on exfoliated graphene-silver nanowires-colorless polyimide

Transparent conductive films with high stability were prepared by embedding silver nanowires in colorless polyimide and adding a protective layer of exfoliated graphene. The films exhibit great light transmission and conductivity with a sheet resistance of 22 Ω sq^-1at transmittance of 83%. Due to its special embedded structure, the conductive layer can withstand several peeling experiments without falling off. In addition, the most outstanding advantage is the ultra-high stability of the films, including high mechanical robustness, strong chemical corrosion resistance and high operating voltage capacity. The organic light-emitting diode devices prepared based on this transparent conductive electrode exhibit comparable efficiency to indium tin oxide (ITO) based devices, withC.E._max= 2.78 cd A^-1,P^-1.E._max= 1.89 lm W^-1,EQE_max= 0.89%. Moreover, the efficiencies were even higher than that of ITO devices when the operating voltage of the device exceeds 5 V. The above performances show that the transparent conductive electrode based on this structure has high potential for application in organic electronic devices.

[Clinical characteristics and pregnancy outcomes of pregnant women with left ventricular non-compaction]

Objective: To investigate the clinical characteristics and pregnancy outcomes in pregnant women with left ventricular non-compaction (LVNC). Methods: The clinical data of seven pregnant women with LVNC from January 2011 to December 2021 in Beijing Anzhen Hospital,Capital Medical University were retrospectively analyzed, including age, gestational age of symptom first occured, LVNC history, clinical symptoms, New York Heart Association (NYHA) cardiac function class, echocardiography, blood brain natriuretic peptide (BNP), treatment and the maternal and fetal outcomes. Results: Five cases were diagnosed before pregnancy, of which there were three women with medication; one case diagnosed in the month of pregnancy; one case diagnosed at 36 weeks of gestation. NYHA cardiac function was grade Ⅰ in four cases and grade Ⅱ in three cases before or during the first trimester of pregnancy. Of the five pregnant women who underwent echocardiography, there were one case of left ventricular insufficiency, three cases of mild left ventricular dysfunction and one case of normal left ventricular function before or during the first trimester of pregnancy. Of the five pregnant women to the second and third trimester of pregnancy, there were one case of grade Ⅳ, one case of grade Ⅲ, two cases of grade Ⅱ-Ⅲ and one case of grade Ⅱ in NYHA class ; three cases of left ventricular insufficiency, two cases of normal left ventricular function by echocardiography four cases had cardiac symptoms at 15-24 weeks of gestation and were treated with medication. In four cases, blood BNP increased to 214-1 197 ng/L during pregnancy, and were 89-106 ng/L after termination of pregnancy. There were 4 cases with arrhythmia. Indications for termination of pregnancy: LVNC complicated with heart failure in two cases, LVNC complicated with decreased cardiac function and threatened preterm birth in one case, complicated with pregnancy at full term in two cases, LVNC complicated with severe pulmonary hypertension in one case, and left ventricular dysfunction in one case. Cesarean section in four cases in the third-trimester, in one case in the second-trimester, and forceps curettage in two cases were taken. Two full-term infants,two preterm infants were born without LVNC. Conclusions: Women diagnosed with LVNC and low left ventricular ejection fraction before pregnancy are more prone to decreased cardiac function during pregnancy. Carrying out pregnancy risk assessment and strengthening the multi-disciplinary team management of high risk factors in pregnancy are conducive to achieve good pregnancy outcomes.

[Clinical analysis of pregnancy termination in 167 pregnant women with cardiovascular disease during the first and second trimester]

Objective: To study the risk assessment, method selection and clinical management of pregnancy termination during the first and second trimester of pregnant women with cardiovascular disease. Methods: This study focused on pregnant women with cardiovascular diseases who were admitted to Beijing Anzhen Hospital during the first and second trimester of pregnancy from January 2016 to September 2019, to summarize their clinical characteristics, reasons and methods of pregnancy termination, management and outcomes. Results: Among 167 pregnant women, 119 cases (71.3%, 119/167) were in early pregnancy and 48 cases (28.7%, 48/167) were in middle pregnancy. The reasons for termination of pregnancy were cardiovascular disease (109 cases; 65.3%, 109/167), unwanted pregnancy (54 cases; 32.3%, 54/167) and other reasons (4 cases). Vacuum aspiration was performed in 98 cases and forceps curettage was performed in 19 cases, medical abortion was performed in 2 cases in early pregnancy. There was no change in cardiac function after pregnancy termination and all survived in early pregnancy. In the second trimester, 16 cases were induced by intraamniotic injection of ethacridine, 2 cases by water balloon, 1 case by oxytocin intravenous drip, and 29 cases by hysterotomy delivery. The ratio of patients with hysterotomy delivery with cardiac function grade Ⅲ-Ⅳ was significantly higher than that in the patients with vaginal labor induction in the second trimester [79% (23/29) vs 4/19; P<0.01]; the ratio of pregnancy risk grade Ⅳ-Ⅴ was also significantly higher [100% (29/29) vs 14/19; P=0.007]. The mean length of hospital stay of patients with hysterotomy delivery was significantly longer than that in the patients with vaginal labor induction [(7.1±3.4) vs (2.4±1.8) days; P<0.01]. Cardiac function was improved in 4 patients induced by ethacridine and rapid recovery without serious complications. Cardiac function decreased in 5 cases and 1 case died on the first day after hysterotomy delivery. Conclusions: Pregnancy risk assessment should be conducted as early as possible in patients with cardiovascular disease. If it is not suitable to continue the pregnancy, terminate pregnancy as early as possible to reduce the risk. Pregnancy termination methods and analgesic methods should be selected according to different gestational age and complications. The indications for hysterotomy delivery should not be relaxed at will, so as to minimize trauma and hemodynamic changes. After the termination of pregnancy, contraceptive measures should be implemented and the next treatment plan should be guided.

[Efficacy and safety of specific sublingual immunotherapy in children with allergic asthma and rhinitis]

Objective:To evaluate the efficacy and safety of specific sublingual immunotherapy (SLIT) with Dermatophagoides farina drops in different courses with allergic asthma and allergic rhinitis.Method:This study retrospectively analyzed the efficacy of SLIT in 158 children with allergic asthma and rhinitis which induced by house dust mites. The children were treated with Dermatophagoides farina drops; clinical observation and follow-up study were conducted. According to the treatment duration, children were divided into 4 groups (1-year, 2-year, 3-year, and 4-year). Symptom scores and medication scores were recorded at each visit. Asthma symptom scores (day and night), the rhinitis symptom scoresand medication scores were evaluated in 4 groups before and after SLIT. The adverse events during the treatment were collected.Result:There were significant differences in asthma symptom scores (day, night), asthma medication scores, rhinitis symptom scores, rhinitis medication scores among children who accepted 1-year, 2-year, 3-year and 4-year SLI treatment as compared with baseline (P< 0.01). As compared with 1-year, 2-year, 3-year groups, the asthma medication scores of 4-year group had obviously decrease (P< 0.05). Rhinitis medication score of SLIT3 years group was significantly lower than 2 years group (P< 0.05). Asthma symptom scores in the day, asthma symptom scores at night, rhinitis symptom scores of four groups children had no statistically significant difference (P>0.05).Conclusion:Different courses of sublingual immunotherapy with Dermatophagoides farina drops had significant effects; the 4-year course of treatment showed the best effect.