Photoconductive properties of Bi2S3 nanowires

The photoconductive properties of Bi2S3 nanowires synthesized inside anodized alumina (AAO) membrane have been characterized as a function of illuminating photon energy between the wavelengths of 500 to 900 nm and at constant illumination intensity of 1–4 μW·cm−2. Photoconductivity spectra, photocurrent values, photocurrent onset/decay times of individual Bi2S3 nanowires liberated from the AAO membrane were determined and compared with those of arrays of as-produced Bi2S3 nanowires templated inside pores of AAO membrane. The alumina membrane was found to significantly influence the photoconductive properties of the AAO-hosted Bi2S3 nanowires, when compared to liberated from the AAO membrane individual Bi2S3 nanowires, possibly due to charge carrier trapping at the interface between the nanowire surface and the pore walls

Photoconductive properties of Bi2S3 nanowires

The photoconductive properties of Bi2S3 nanowires synthesized inside anodized alumina (AAO) membrane have been characterized as a function of illuminating photon energy between the wavelengths of 500 to 900 nm and at constant illumination intensity of 1–4 μW·cm−2. Photoconductivity spectra, photocurrent values, photocurrent onset/decay times of individual Bi2S3 nanowires liberated from the AAO membrane were determined and compared with those of arrays of as-produced Bi2S3 nanowires templated inside pores of AAO membrane. The alumina membrane was found to significantly influence the photoconductive properties of the AAO-hosted Bi2S3 nanowires, when compared to liberated from the AAO membrane individual Bi2S3 nanowires, possibly due to charge carrier trapping at the interface between the nanowire surface and the pore walls

Intrauterine growth restriction: distribution, risk factors, management of labour and outcome

Background: The development of Intrauterine growth restriction (IUGR) determines maternal, fetal and placental factors. Many of these factors are preventable. There is still no enough developed effective pregnancy and labour management tactics that could protect both mother and child from the unintended consequences.Methods: The research was made in Riga Maternity Hospital. In the research there were included pregnant women who gave birth neonates with weight under 10th percentile (IUGR group) as well there was compiled the control group. The weight of neonates was evaluated using the percentile scales - Intrauterine Growth Curves based on US data.Results: According to the criteria, in the IUGR group were included 209 pregnant women and in the control group was the same number of patients. In the IUGR group mothers discharged from the hospital one day later than it was in the control group both after vaginal delivery (4.0 ± 1.5 vs. 3.3 ± 1.0, p˂0.0001) and after caesarean (5.6 ± 1.5 vs. 4.5 ± 1.0, p=0.0001). Comparing the evaluations after Apgar scale after spontaneous birth, induced labour and caesarean it was discovered that there is no statistically significant difference.Conclusions: IUGR negatively affect not just the fetus but also the mother and this is the reason why she should stay in the hospital for a longer period due to the child or experience the caesarean.

Intrapartum ultrasound to predict vaginal labor: a prospective cohort study

Background: Non-invasive transperineal ultrasound has been used to detect the descent of the fetal head using head-perineum distance (HPD) and angle of progression (AOP). The aim was to evaluate HPD and AOP as predictors of vaginal delivery in the first stage of labor.Methods: This was a prospective cohort study in Riga Maternity Hospital in Latvia from May till August 2016. The study included only nulliparous women with singleton pregnancies and cephalic presentation. Ultrasound was used to measure HPD and AOP. Data was collected on demographics, labor parameters and outcome.Results: Of 36 women enrolled, 26 (72.2%) had a vaginal delivery. The area under the receiver–operating characteristics curve for the prediction of vaginal delivery was 0.865 (95% confidence interval (CI) 0.75-0.98) using HPD as the test variable and the area under the curve was 0.877 (95% CI 0.77-0.99) for AOP. The median HPD was lower in the women delivering vaginally than in the women delivering by cesarean section (P40 mm in the other 18 women, of whom 8 (22.2%) delivered vaginally (P<0.001). AOP was ≥105° in 22 (61.1%) women and, of these, 21 delivered vaginally. AOP was <105° in the other 14 (38.9%) women, of whom 5 delivered vaginally (P<0.001).Conclusions: HPD ≤40 mm and AOP ≥105° are both predictive of vaginal delivery in the first stage of labor

Expectant management of intrauterine growth restriction pregnancy: perinatal outcome

Background: Intrauterine growth restriction (IUGR) is the reason for increased morbidity and mortality in all periods of human life. The development of this pathology defines a variety of factors many of which are preventable. There is still no developed effective tactics for pregnancy and delivery, which would protect both mother and child from undesirable consequences.Methods: The research was made in Riga Maternity hospital in Latvia. In the research were included 96 neonates with the weight below 10th percentile (IUGR group) as well there was compiled the control group. We evaluated the condition of neonate by 13 criteria and studied its frequency depending on the gestational period. The weight of neonates was estimated using the percentile scales - intrauterine growth curves based on U.S. data.   Results: In the subgroup of 37-39th week in the IUGR group in comparison with 40-42nd week subgroup, statistically more often was noticed hypoglycaemia, polycythaemia, acidosis, poor feeding, neurological abnormalities, transportation to an intensive care unit, transportation to another hospital for the further treatment and there was a higher number of days spent in the hospital. In the subgroup of 37-39th week in the control group were just 2 criteria that were statistically more frequent.Conclusions: Recognizing the IUGR to the fetus, there is justified the temporizing tactics with regard to resolution of pregnancy if only the health status of mother allows that and preeclampsia is excluded

Impact of Intraoperative Factors on the Development of Postpartum Septic Complications

Publisher Copyright: © 2023 by the authors.Background and Objectives: Triclosan-coated sutures (antibacterial sutures) can reduce the risk of postoperative surgical site infection. This study aimed to investigate the effect of intraoperative factors, including antibacterial sutures, on the risk of postpartum septic complications. Materials and Methods: The prospective study included patients who underwent caesarean section. The exclusion criterion was chorioamnionitis. The investigation group patient’s (n = 67) uterus and fascial sheath of the abdominal wall were sutured with triclosan-coated polyglactin 910 sutures during surgery. The control group consisted of 98 patients using uncoated polyglactin 910 sutures only. The patients were contacted by phone after the 30th postoperative day. Results: No significant difference was found between the investigation group and the control group in the development of postpartum endometritis (11.7% in the investigation group vs. 8.4% in the control group, p = 0.401), wound infection (6.3% vs. 3.6%, p = 0.444) or patients experienced any septic complication (15.9% vs. 12%, p = 0.506). Postpartum endometritis was more common in patients who underwent instrumental uterine examination during the surgery (23.8% vs. 18%, p = 0.043). A moderately strong correlation was found for haemoglobin level on the third–fourth postoperative day with the development of postpartum septic complications, p < 0.001, Pearson coefficient −0.319. Post-caesarean delivery septic complications were not statistically more common in patients with blood loss greater than 1 L. The incidence of post-caesarean endometritis was 13.4%, and wound infection was 4.8% in this study’s hospital, having five to six thousand deliveries per year. Conclusions: Using antibacterial sutures during caesarean section does not affect the incidence of postpartum septic complications. Instrumental uterine examination during caesarean section increases the risk of post-caesarean endometritis and is, therefore, not recommended. Haemoglobin level on the 3rd–4th postoperative day, rather than the estimated blood loss during surgery, affects the development of postpartum septic complications.Peer reviewe

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

Funding Information: This work was supported by the Latvian Council of Science (project No. 549/2012) and the University of Latvia project No. AAP2016/B043 and No. ZD2010/AZ19. Publisher Copyright: © 2018 Jasulaneca et al.; licensee Beilstein-Institut. License and terms: see end of document.This review summarizes relevant research in the field of electrostatically actuated nanobeam-based nanoelectromechanical (NEM) switches. The main switch architectures and structural elements are briefly described and compared. Investigation methods that allow for exploring coupled electromechanical interactions as well as studies of mechanically or electrically induced effects are covered. An examination of the complex nanocontact behaviour during various stages of the switching cycle is provided. The choice of the switching element and the electrode is addressed from the materials perspective, detailing the benefits and drawbacks for each. An overview of experimentally demonstrated NEM switching devices is provided, and together with their operational parameters, the reliability issues and impact of the operating environment are discussed. Finally, the most common NEM switch failure modes and the physical mechanisms behind them are reviewed and solutions proposed.publishersversionPeer reviewe

Low-Vacuum Catalyst-Free Physical Vapor Deposition and Magnetotransport Properties of Ultrathin Bi2Se3 Nanoribbons

In this work, a simple catalyst-free physical vapor deposition method is optimized by adjusting source material pressure and evaporation time for the reliable obtaining of freestanding nanoribbons with thicknesses below 15 nm. The optimum synthesis temperature, time and pressure were determined for an increased yield of ultrathin Bi2Se3 nanoribbons with thicknesses of 8–15 nm. Physical and electrical characterization of the synthesized Bi2Se3 nanoribbons with thicknesses below 15 nm revealed no degradation of properties of the nanoribbons, as well as the absence of the contribution of trivial bulk charge carriers to the total conductance of the nanoribbons

High transparency Bi2Se3 topological insulator nanoribbon Josephson junctions with low resistive noise properties

Bi$_2$Se$_3$ nanoribbons, grown by catalyst-free Physical Vapour Deposition, have been used to fabricate high quality Josephson junctions with Al superconducting electrodes. The conductance spectra (dI/dV) of the junctions show clear dip-peak structures characteristic of multiple Andreev reflections. The temperature dependence of the dip-peak features reveals a highly transparent Al/Bi$_2$Se$_3$ topological insulator nanoribbon interface and Josephson junction barrier. This is supported by the high values of the Bi$_2$Se$_3$ induced gap and of I$_c$R$_n$ (I$_c$ critical current, R$_n$ normal resistance of the junction) product both of the order of 160 $\mu$eV, a value close to the Al gap. The devices present an extremely low relative resistance noise below 1$\times$10$^{-12}$ $\mu$m$^2$/Hz comparable to the best Al tunnel junctions, which indicates a high stability in the transmission coefficients of transport channels. The ideal Al/Bi$_2$Se$_3$ interface properties, perfect transparency for Cooper pair transport in conjunction with low resistive noise make these junctions a suitable platform for further studies of the induced topological superconductivity and Majorana bound states physics.Comment: The following article has been accepted by Applied Physics Letter

Synthesis, magnetoresistance, and thermoelectrical properties of environmentally stable n-type nitrogen-doped multiwalled carbon nanotubes

This work was funded by the European Regional Development Fund (ERDF) project no. 1.1.1.1/19/A/138. A.S. and K. S. acknowledge the funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2.Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) are known as a perspective material for a variety of applications in nanoelectronic devices, sensors, catalysts for carbon dioxide reduction, and flexible thermoelectrics. However, up to date most of the reports on the properties of N-MWCNTs are focused on a narrow niche of research, for example, a study of low-temperature magnetoresistance or room-temperature thermoelectrical properties. In this work, N-MWCNTs were synthesized using benzene:pyridine precursor in different ratios, and both magnetoresistance and thermoelectrical properties of the synthesized N-MWCNTs were systematically investigated in the temperature range 2-300 K and compared with the properties of undoped MWCNTs. Unexpected switching of the magnetoresistance of the N-MWCNTs at low temperatures from negative to positive values was observed, and the processes underlying this effect are discussed. The study of the thermoelectrical properties revealed n-type conductance in the N-MWCNTs, which was attributed to the impact of nitrogen defects incorporated in the MWCNT structure. Performed for the first-time investigations of the thermal stability of the Seebeck coefficient of N-MWCNTs in air revealed that the Seebeck coefficient retains its negative values and even increases after annealing of the N-MWCNTs in air at 500 °C. These findings illustrate the high potential of the presented in this work N-MWCNTs for applications in different devices in a wide range of temperatures. --//-- Jana Andzane, Mikhail V. Katkov, Krisjanis Buks, Anatolijs Sarakovskis, Krisjanis Smits, Donats Erts, Synthesis, magnetoresistance, and thermoelectrical properties of environmentally stable n-type nitrogen-doped multiwalled carbon nanotubes, Carbon Trends, Volume 13, 2023,100302, ISSN 2667-0569, https://doi.org/10.1016/j.cartre.2023.100302. (https://www.sciencedirect.com/science/article/pii/S2667056923000573). Published under the CC BY-NC-ND licence.ERDF project no. 1.1.1.1/19/A/138. A.S; European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2