Increase In Pressure Research Articles

Comparative Study of Olmesartan versus Telmisartan, in Patient with Stage I Hypertension

Background: Hypertension is one of the most common diseases in the world. It is defined as sustained increase in blood pressure ≥ 140/90 mmHg. The risk of both microvascular & microvascular complications including stroke, coronary artery disease, peripheral vascular disease, retinopathy, nephropathy & possibly neuropathy increases with hypertension. Olmesartan medoxomil is a non-peptide angiotensin II receptor antagonist. The drug acts by selectively blocking angiotensin II type 1 receptor. Telmisartan is angiotensin receptor blocker shows high affinity for the angiotensin II type 1 receptors. Objective of the study is to compare the efficacy of Olmesartan and Telmisartan in Patient with stage –I hypertension. Materials and methods: This was a randomized, open‑label, parallel‑group, comparative study conducted in 120 patients of Stage I hypertension carried out from January 2021to June 2022. Patients were recruited from the cardiology outpatient department (OPD) of Shaheed Suhrawardy Medical College hospital.Results: In olmesartan group there were 39 male and 21 female patients and in telmisartan group there were 36 male and 24 female patients. Both Olmesartan and Telmisartan are effective in lowering systolic & diastolic BP at different intervals of 2nd, 4th, 8th and 12th week. There was a statistically significant decrease in mean blood glucose level after 12 weeks of treatment in telmisartan group when compared to baseline. Serum total cholesterol, triglycerides, and low‑density lipoproteins decreased significantly after 12‑week treatment with olmesartan and telmisartan. Conclusion: Olmesartan and telmisartan are equally efficacious in reducing DBP. Olmesartan, when compared to telmisartan is more efficacious in reducing SBP. Whereas Telmisartan shows the most favorable effects on FBG and lipid profile. J Shaheed Suhrawardy Med Coll 2023; 15(1): 8-12

Stress-induced arterial hypertension: search for predictors

Background. Despite the existence of a clear cause-and-effect relationship between job strain and hypertension, there are still no clear criteria for defining stress-induced arterial hypertension (SIAH). Objective. Search for SIAH criteria, in particular predictors of hypertension in the workplace. Materials and methods. The study included volunteers experiencing stress in the workplace and not having hypertension. Before the start of the working day and at the end of the working day, the subject was surveyed, given questionnaires (Ch. D. Spielberg scale, Montgomery-Asberg MADRS scale, A. M. Vein scale, hospital anxiety and depression scale HADS), blood pressure and resting heart rate were measured, fasting blood was taken to determine the values of ACTH, TSH, T4, insulin, cortisol. All patients underwent ABPM on a working day and a day off. Results. According to ABPM (n=52), no signs of masked hypertension were detected, however, significant differences between workdays and weekends in the levels of maximum SBP and DBP during the daytime were noteworthy. In the group with maximum SBP>140 mm Hg during the daytime (SIAH, n = 34), on a workday there was an increase in the time index for SBP>30% (24 hours and day), characteristic of hypertension, and for DBP (24 hours and day), characteristic of borderline (possible) hypertension, the average DBP values during the day and at night were at the upper limit of the norm, which was significantly different from the Normotonic group (n = 19). On a weekday, the SIAH group also had significantly increased SBP (24 hours, day) and DBP (24 hours, day and night) indexes versus Normotonic. For all other indicators except ABPM, the groups were comparable. Conclusions. Taking into account the increase in the time index for SBP and DBP, it can be assumed that, against the background of stressful situations at the workplace, the subjects had short frequent increases in blood pressure, which have not yet led to a significant violation of self-regulation of blood pressure and the development of hypertension. An increase in the maximum values of systolic and/or diastolic blood pressure against the background of an increased time index on a working day are possible predictors of SIAH, in particular hypertension at the workplace.

Analysis of the role of low molecular weight heparin in preeclampsia and fetal growth restriction syndrome: A systematic review

Introduction: preeclampsia is defined as hypertension during pregnancy and this increase in blood pressure can lead to serious and unwanted decompensations for both the mother and the fetus. It has been shown that among the factors that lead to maternal death, PE ranks third, not being surpassed only by hemorrhages and thrombosis.Objective: to determine the role of low molecular weight heparin in preeclampsia and fetal growth restriction syndrome.Method: a systematic review of the literature was carried out addressing the analysis of the efficacy and safety of low molecular weight heparin in the treatment of preeclampsia. The articles were searched in the following databases such as Pubmed, Elsevier in the following languages: English, Spanish and Portuguese, from the last 20 years.Results: 16 studies that met the inclusion criteria were included and 25,261 pregnant women were analyzed.Conclusion: the analysis carried out shows that the efficacy of using LMWH in preeclampsia and fetal growth restriction syndrome can be an option in the treatment and prevention, however a great heterogeneity was detected in the results of the trials, which does not yet allow its use in medical practice

Status of Horizontal Violence, Level of Psychological Empowerment, and Their Correlation Among Obstetric Nurses: A Cross-Sectional Survey.

China's maternity policy has led to an increase in work pressure, which has prompted horizontal violence among obstetric nurses. To understand this phenomenon better, we attempted to identify the factors that influence horizontal violence as well as the level of psychological empowerment among obstetric nurses. This cross-sectional survey was conducted among 522 obstetric nurses from December 2022 to February 2023. The findings revealed that 40.42% (211) of the obstetric nurses had experienced horizontal violence in the past 3 months. The overall level of psychological empowerment of obstetric nurses was relatively low. Regression analysis indicated that being a formal worker, being from the area where one serves, the meaning attributed to work, and perceptions of autonomy, self-efficacy, and work impact acted as protective factors against the risk of horizontal violence among obstetric nurses. When compared with the 20-29-year-old age group, those in the 30-39-year-old age group showed a lower risk of experiencing horizontal violence (odds ratio [OR] = 0.369, p < 0.01). Compared with nurses who had worked in obstetrics for < 3 years, those who had worked for 3-5, 6-10, 11-20, and > 20 years showed lower risks of experiencing horizontal violence than the reference level (OR = 0.234, p < 0.05; OR = 0.182, p < 0.05; OR = 0.105, p < 0.05; and OR = 0.056, p < 0.05, respectively). The incidence of horizontal violence among obstetric nurses is high, and the overall level of psychological empowerment is low. Nursing managers can alleviate the occurrence of horizontal violence by augmenting the psychological empowerment level of obstetric nurses.

Ringer’s lactate administered at 15 °C leads to a greater and more prolonged increase in blood pressure compared to 37 °C

18 Participants were randomized to receive 30 ml/kg bodyweight Ringer’s Lactate at 37° or 15 °C over 30 min. In a second session, participants were crossed over. Over a 120 min period after starting the fluid bolus we measured mean arterial pressure (MAP), cardiac output, systemic vascular resistance, and catecholamine levels. After infusion with cold fluids, the absolute increase in MAP at 45 min was significantly higher at + 6.5 mmHg (95% CI 4.8–8.2) compared with warm fluids (+ 0.6 mmHg, 95% CI, − 1.6 to 2.8; p < 0.001). This increase in MAP was longer-lasting after cold fluids (81.7 min, 95% CI 62.5–100.9) than after warm fluids (19.2, 95% CI 3.4–35; p < 0.001). While cardiac output was similar, systemic vascular resistance increase was greater after cold fluids (159 dyn s/cm5, 95% CI 9.5–309) compared to warm fluids (− 66 dyn s/cm5, 95% CI − 191 to 57; p = 0.012). Moreover, noradrenaline increased by up to 246% during cold fluids, and decreased with warm fluids (p < 0.001). Fluid bolus given at 15 °C, compared to 37 °C, leads to a greater and more prolonged increase in MAP accompanied by release of intrinsic noradrenaline and vasoconstriction. These results suggest that fluid temperature rather than volume is predominantly responsible for any increase in MAP.Trial Registration: EudraCT-nummer 2022-002137-34 and clinicaltrials.gov NCT05610254 (first registration 09/11/2022).

Caffeine and Vision: Effects on the Eye.

Caffeine, commonly found in coffee and tea, affects various aspects of eye health as it blocks adenosine receptors, impacting tear production, intraocular pressure, macular perfusion, and choroidal thickness. However, its connection with eye conditions like glaucoma and cataracts remains uncertain due to conflicting research findings. Some studies suggest potential benefits for cataracts, while others warn against frequent caffeine intake in glaucoma and surgical scenarios due to possible increases in intraocular pressure. Conflicting evidence also exists regarding its effects on dry eye, macular degeneration, myopia/hyperopia, diabetic retinopathy, retinopathy of prematurity, and central serous retinopathy. Caffeine does not seem to be a risk factor for dry eye, although studies have shown that caffeine may offer protection against wet age-related macular degeneration, and the metabolite 7-methylxanthine could be a more promising treatment for myopia. Moreover, caffeine can potentially cause tremors and might hinder surgical performance, especially in less experienced surgeons. Recommendations from experts vary, highlighting the need for further research to fully understand how caffeine affects the eye. Individuals genetically predisposed to glaucoma should be cautious due to the possibility of clinically significant elevations in intraocular pressure with caffeine consumption. For delicate procedures like microsurgery, where tremors can be detrimental, caution should be exercised with caffeine. This review underscores the importance of additional studies to provide clearer insights and prudent recommendations regarding caffeine's impact on eye health.

Collagenous enteritis as a rare cause of exudative enteropathy in a child. Case report

Exudative enteropathy (EE) syndrome can be associated with various diseases of the gastrointestinal tract (GIT) and is manifested by edematous syndrome, hypoproteinemia, hypoalbuminemia, lymphocytopenia, hypogammaglobulinemia, and an increase in the level of α-1-antitrypsin in the feces. More than 60 medical conditions are associated with loss of protein through the gastrointestinal tract, including erosive-ulcerative diseases of the gastrointestinal tract, non-erosive lesions of the mucous membrane causing an increase in the permeability of the intestinal wall, as well as disorders with an increase in pressure in the lymphatic system. Correct diagnosis and timely replacement and pathogenetic therapy are essential for the rapid cessation of pathological losses, the recovery of the proteinogram, and the prevention of life-threatening complications. Collagenous enteritis is one of the rare diseases of the small intestine associated with EE syndrome. The article presents a clinical case of a young child with EE and collagenous enteritis. The stages of the diagnostic workup in detecting EE syndrome in the child are discussed, and the pathogenetic factors that determined the development of this disorder are considered.

The first-principles prediction of mechanical, electronic, elastic and thermodynamic properties of Mo2XB2 (X=Nb, Os, Ta)

The mechanical, electronic and elastic properties of Mo2XB2 (X = Nb, Os, Ta) at different pressures (0–50 GPa) were predicted using first-principles calculations. The enthalpy of formation and the elastic constant calculations show that the three transition metal borides are thermodynamically and mechanically stable. The analysis of density of state and band structure reveals that Mo2XB2 (X = Nb, Os, Ta) have metallic and covalent properties. The increase of pressure will increase the elastic modulus of Mo2XB2 (X = Nb, Os, Ta). The elastic modulus of Mo2XB2 (X = Nb, Os, Ta) are anisotropic. Furthermore, the quasi-harmonic Debye model is used to predict thermodynamic parameters at various temperatures (0–1200K) and pressures (0–50 GPa), such as heat capacity at constant pressure, heat capacity at constant volume, coefficient of thermal expansion, Debye temperature, and the Grüneisen parameter.

Potential of observing the diameter of the optic nerve sheath using computed tomography in diagnosing high intracranial pressure in patients with spontaneous CSF rhinorrhea.

Spontaneous cerebrospinal fluid rhinorrhea (sCSFR) is often accompanied by an increase in intracranial pressure (ICP). The widening of optic nerve sheath diameter (ONSD) is an indicator of increased ICP. Using CT to measure ONSD is a simple and noninvasive auxiliary method for determining high ICP in sCSFR patients.

Effects of discharge parameters on plasma acceleration and transmission characteristics of a coaxial gun operated in gas-prefilled mode

The effects of discharge parameters on the discharge process and plasma transport characteristics of a coaxial gun in the gas-prefilled mode are studied. The plasma optical intensity and ejection velocity are measured by photodiodes, the optical emission spectrum is taken by a spectroscopic system, and the plasma evolution in the transport process is captured by a high-speed camera. The plasma acceleration characteristics under different discharge parameters show that the velocity and electron density of the ejection plasma are mainly determined by the pre-filled pressure and discharge current, which is consistent with the snowplow model. The kinetic energy of ejection plasma can be significantly increased by reducing the outer loop inductance, which is conducive to increasing the energy utilization efficiency. The time-varying images of plasma radiation and the plasma density at different transport locations illuminate the transmission characteristics of coaxial gun discharge plasma. The results show that the snowplow effect continues to play a role in the plasma transport process, and the plasma accumulation is induced by the combination of shock wave compression. The current-driven magneto hydrodynamics instability occurs during the transport process, and the luminous signal of the plasma current sheet oscillates periodically. In addition, the plasma impact effect is obvious and the gas retarding effect is enhanced with the increase in the gas pressure. These results give us a more comprehensive view of the coaxial gun discharge process and plasma transport and provide a certain reference for optimizing the parameters selection and physical design of coaxial gun discharge plasma characteristics.

Time Interval Between Right Ventricular Early Diastolic Velocity by Tissue and Pulse Wave Doppler: An Index of Right Atrial Pressure in Pulmonary Hypertension Patients.

Background: A reversal of time difference between the onset of early diastolic velocity (e') during tissue Doppler imaging and the onset of mitral inflow (E) has been observed in cases of elevated left atrial pressure. Whether this interval (Te'-E) may be useful to assess right atrial pressure has never been investigated, neither in healthy subjects nor in pulmonary hypertension patients. Methods: Right ventricular Te'-E was assessed in patients with pre-capillary pulmonary hypertension and compared with healthy volunteers who underwent comprehensive echocardiography examination. Te'-E is the difference between the interval from R wave at the superimposed electrocardiogram to the e' wave during right ventricular tissue Doppler imaging and the interval from the R wave to transtricuspid E wave during pulsed wave Doppler imaging. Right atrial pressure was invasively measured in pulmonary hypertension patients. Results: Fifty-six patients were enrolled. Te'-E was prolonged in pulmonary hypertension subjects compared with healthy subjects (p < 0.001). Amongst the pulmonary hypertension patients, strong correlations were found between Te'-E and right atrial pressure (r = -0.885, p < 0.001), systolic pulmonary pressure (r = -0.85, p < 0.001) and the duration of tricuspid regurgitation (r = 0.72, p < 0.001). The area under the receiver operating characteristic curve of Te'-E in identifying right atrial pressure higher than 15 mm of mercury was 0.992 (sensitivity 100%, specificity 83%). Conclusions: In contrast to the left ventricle, there is a delay in the proto-diastolic filling in pulmonary hypertension patients, which correlates with the increase in systolic pulmonary arterial pressure, right atrial pressure, tricuspid regurgitation duration and restrictive diastolic pattern.

Salt Responsive Gut Microbiota Induces Sex Specific Blood Pressure Changes.

Tryptophan metabolism is important in blood pressure regulation. The tryptophan-indole pathway is exclusively mediated by the gut microbiota. ACE2 (angiotensin-converting enzyme 2) participates in tryptophan absorption, and a lack of ACE2 leads to changes in the gut microbiota. The gut microbiota has been recognized as a regulator of blood pressure. Furthermore, there is ample evidence for sex differences in the gut microbiota. However, it is unclear whether such sex differences impact blood pressure differentially through the tryptophan-indole pathway. To study the sex-specific mechanisms of gut microbiota-mediated tryptophan-indole pathway in hypertension, we generated a novel rat model with Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9)-targeted deletion of Ace2 in the Dahl salt-sensitive rat. Cecal microbiota transfers from donors of both sexes to female S recipients were performed. Also, Dahl salt-sensitive rats of both sexes were orally gavaged with indole to investigate blood pressure response. The female gut microbiota and its tryptophan-indole pathway exhibited greater buffering capacity when exposed to tryptophan, due to Ace2 deficiency, and salt. In contrast, the male gut microbiota and its tryptophan-indole pathway were more vulnerable. Female rats with male cecal microbiota responded to salt with a higher blood pressure increase. Indole, a tryptophan-derived metabolite produced by gut bacteria, increased blood pressure in male but not in female rats. Moreover, salt altered host-mediated tryptophan metabolism, characterized by reduced serum serotonin of both sexes and higher levels of kynurenine derivatives in the females. We uncovered a novel sex-specific mechanism in the gut microbiota-mediated tryptophan-indole pathway in blood pressure regulation. Salt tipped the tryptophan metabolism between the host and gut microbiota in a sex-dependent manner. Our study provides evidence for a novel concept that gut microbiota and its metabolism play sex-specific roles in the development of salt-sensitive hypertension.

Interplay of pressure and temperature in modulating the magnetic properties of Cr2O3

The spin-lattice interaction is pivotal in tailoring materials properties and is crucial for developing novel spintronic devices. In the current work, we aim to explore the effects of pressure and temperature on the magnetic properties of Cr2O3 to gain insights into its spin-lattice interaction. Through high-pressure neutron diffraction experiments, we observed an enhancement of the magnetic Bragg intensity with increasing pressure and it becomes more pronounced as the temperature increases. Results from first-principles calculations reveal a strengthening of the easy-axis magnetic anisotropy, doubling from 0 to 20 GPa. The exchange parameters, calculated based on this spin orientation, show an enhancement of the dominant magnetic interactions and an increase of magnetic ordering temperature when pressure increases. These findings suggest that the contributions from these two mechanisms are responsible for the observed increase in magnetic Bragg intensity.

The Influence of Pressure on the Electronic and Elastic Characteristics of GaP Nanocrystals using Density Functional Theory

The electronic structural and mechanical properties of III-V Gallium Phosphide (GaP) nano-crystals zinc-blende stable (ZB) phase under pressure dependence have been studied via the model of the density functional theory (DFT) in combination with the large unit cell (LUC) approach at (8, 16, 54 &amp; 64) atoms. The exchanges and correlations (XC) energy has been defined in all approaches through generalized gradient approximations of the Perdew-Burke-Ernzerhof (GGA-PBE), and determination of GaP characteristics in the case where the pressure has been increased from 0GPa to ±50GPa. Elastic parameters like elastic constants (C11, C12 &amp; C44), Kleinmann parameter (ξ), Zener anisotropic factor (A), shear modulus (G), Young's modulus (E), Poisson’s ratio (v), Bulk modules (B) of GaP-ZB structure have been calculated and showed systematic variation with a pressure increase. Our calculations show that Bulk modules and sound speed increase with an increase in the number of core atoms. In this systematic approach, it has been found that the B/G ratio is 1.58 for this compound and it exhibits a negative Cauchy pressure, classifying GaP as brittle. The results were discovered to be consistent with other theoretical as well as experimental results. The present study directly relates to the latest experimental works on the III-phosphide compounds. The current results provide information and direction for further investigation into the fundamentals and potential applications of gallium phosphate (GaP) nanocrystals. In addition, we attempted to compare the results of the investigation with some similar types of compounds that are already documented in the literature. We believe that our study will have a significant impact on both the field of research and contemporary technology based on semi-conducting materials.

Shifts in geographic vulnerability of US corn crops under different climate change scenarios: corn flea beetle (Chaetocnema pulicaria) and Stewart’s Wilt (Pantoea stewartii) bacterium

Abstract Changing climate patterns will likely affect insect pressure on many agricultural crops. Mild winters may decrease the number of insects that experience reduced fecundity or that are killed during hard freezes. This may result in larger populations in subsequent years and allow for range expansion. Direct effects from pests are compounded by indirect effects, such as crop damage resulting from insect-vectored diseases. Corn flea beetle (Chaetocnema pulicaria) infestations have both direct and indirect effects on crops. This beetle is a pest on all types of corn in the United States, including sweet corn and grain corn (sometimes referred to as dent corn). It is responsible for damage to plant foliage and also serves as the primary overwintering vector for Pantoea stewartii bacterium, which causes Stewart’s Wilt, a disease that can severely impact the health and productivity of corn. Evidence suggests that warmer winters will contribute to a geographic range expansion for the corn flea beetle. Here we show the projected northward expansion of economically damaging crop losses caused by Stewart’s Wilt: (A) from 1980 to 2011, (B) projected by mid-century, and (C) projected by end-century. Our work suggests that climate change and associated increasing winter temperatures in the United States will lead to a dramatic increase in the probability of severe damage from corn flea beetle across the United States, including the Corn Belt. Predicted increases in pest and disease pressure will have negative ramifications for corn production and are likely to exacerbate issues associated with specific management tactics, such as pesticide application.

Seismic nonlinear interaction and uplifting effects between the nuclear island building and soil

Since the Fukushima nuclear accident, seismic design requirements have increased, necessitating a more refined evaluation of base uplift for weakly anchored nuclear island buildings. The elevated cooling water over 3000 t is a distinguishing feature of third-generation reactor buildings (RBs). To assess potential safety-adverse coupling effects, seismic wave propagation process through viscoelastic soils, discontinuous interfaces, and sloshing water was analysed. To facilitate nonlinear systematic simulation and parametric study, the traditional soil-structure interaction direct methods are improved and programmed on: thickness-independent viscous-spring elements for stable static-dynamic boundary transitions; seismic forces separated from the artificial boundary for flexible mesh planning; elevated water simulated with gravity stacking and hydrodynamic action. A nuclear island region encompassing water-cooled RBs and underlying soil cushion layer was investigated as a typical scenario to reveal rules using the proposed high-precision simulation platform. Non-negligible structural risks and correlations between multiple factors were quantitatively elucidated according to simulation findings. A time-lagged increase in the base overturning moment may occur because of water oscillations. As the water level increases to 85 %, the uplift height increases, adversely affecting the in-structure response spectra. Earthquake-induced intense uplift may lead to an increase in hydrodynamic pressure along the inner wall. The research results support the practical assessment of buildings with water cooling facilities located in soft composite sites with high seismic intensities.

Impact of arterial system alterations due to amputation on arterial stiffness and hemodynamics: a numerical study

Subjects with amputation of the lower limbs are at increased risk of cardiovascular mortality and morbidity. We hypothesize that amputation-induced alterations in the arterial tree negatively impact arterial biomechanics, blood pressure and flow behavior. These changes may interact with other biological factors, potentially increasing cardiovascular risk. To evaluate this hypothesis regarding the purely mechanical impact of amputation on the arterial tree, we used a simulation computer model including a detailed one-dimensional (1D) arterial network model (143 arterial segments) coupled with a zero-dimensional (0D) model of the left ventricle. Our simulations included five settings of the arterial network: (1) 4-limbs control, (2) unilateral amputee (right lower limb), (3) bilateral amputee (both lower limbs), (4) trilateral amputee (lower-limbs and right upper-limb), and (5) quadrilateral amputee (lower and upper limbs). Analysis of regional stiffness, as calculated by pulse wave velocity (PWV) for large-, medium- and small-sized arteries, showed that, while aortic stiffness did not change with increasing degree of amputation, stiffness of medium and smaller-sized arteries increased with greater amputation severity. Despite a staged decrease in cardiac output, the systolic and diastolic blood pressure values increased, resulting in an increase in both central and peripheral pulse pressures but with an attenuation of pulse pressure amplification. The most significant increase in peak systolic pressure and decrease in peak systolic blood flow was observed at the site of the abdominal aorta. Wave separation analysis indicated no changes in the shape of the forward and backward wave components. However, the results from wave intensity analysis showed that with extended amputation, there was an increase in peak forward wave intensity and a rise in the inverse peak of the backward wave intensity, suggesting potential alterations in cardiac hemodynamic load. In conclusion, this simulation study showed that biomechanical and hemodynamic changes in the arterial network geometry could interact with additional risk factors to increase the cardiovascular risk in patients with amputations.

Effect of pressure on the sintering mechanisms of tantalum carbide ceramics

AbstractHigh pressure sintering shows great superiority in promoting the densification of the hard‐to‐densify refractory ceramics, and the underlying mechanisms are thus of great interest. In the present work, the densification process of tantalum carbide (TaC) ceramics affected by pressure was discussed through comparing the microstructural characteristics and sintering kinetics. The TaC ceramics sintered at 30–250 MPa show dense and uniform microstructure without oxide impurities and high‐density dislocations. With the increase of sintering pressure, particle rearrangement becomes prominent at initial stage, whereas grain boundary diffusion rather than lattice diffusion dominants the final stage mechanism. Grain growth is enhanced under high pressure through the plastic deformation process. Our work should facilitate to understand the mass transport mechanisms during the high pressure sintering or deformation process of carbide ceramics.

Dynamical downscaling and data assimilation for a cold-air outbreak in the European Alps during the Year Without a Summer of 1816

Abstract. The “Year Without a Summer” in 1816 was characterized by extraordinarily cold and wet periods in central Europe, and it was associated with severe crop failures, famine, and socio-economic disruptions. From a modern perspective, and beyond its tragic consequences, the summer of 1816 represents a rare opportunity to analyze the adverse weather (and its impacts) after a major volcanic eruption. However, given the distant past, obtaining the high-resolution data needed for such studies is a challenge. In our approach, we use dynamical downscaling, in combination with 3D variational data assimilation of early instrumental observations, for assessing a cold-air outbreak in early June 1816. We find that the cold spell is well represented in the coarse-resolution 20th Century Reanalysis product which is used for initializing the regional Weather Research and Forecasting Model. Our downscaling simulations (including a 19th century land use scheme) reproduce and explain meteorological processes well at regional to local scales, such as a foehn wind situation over the Alps with much lower temperatures on its northern side. Simulated weather variables, such as cloud cover or rainy days, are simulated in good agreement with (eye) observations and (independent) measurements, with small differences between the simulations with and without data assimilation. However, validations with partly independent station data show that simulations with assimilated pressure and temperature measurements are closer to the observations, e.g., regarding temperatures during the coldest night, for which snowfall as low as the Swiss Plateau was reported, followed by a rapid pressure increase thereafter. General improvements from data assimilation are also evident in simple quantitative analyses of temperature and pressure. In turn, data assimilation requires careful selection, preprocessing, and bias-adjustment of the underlying observations. Our findings underline the great value of digitizing efforts of early instrumental data and provide novel opportunities to learn from extreme weather and climate events as far back as 200 years or more.

Study on the tunable band gap of LiNaPb2Br6 superlattice and its optical properties

The property changes between APbBr3 (A = Li, Na) and LiPbBr3/NaPbBr3 superlattice (LiNaPb2Br6), as well as the electronic structure and optical properties of LiNaPb2Br6 under various pressures, have been investigated using the GGA-PBE method based on first-principles. The research shows that the band gap (Eg) value of LiNaPb2Br6 is 1.674 eV at 0 GPa, which is between that of LiPbBr3 and NaPbBr3. Meanwhile, the results indicate that the Eg of LiNaPb2Br6 gradually decreases with the increase in pressure, reaching 0.080 eV at 7 GPa, and its valence band top crosses the Fermi level at 8 GPa. Therefore, by combining the construction of superlattices with the application of pressure, the Eg of LiNaPb2Br6 can be continuously regulated in the range of 0–1.674 eV. Since the optical properties of a material primarily depend on its band structure, the optical properties of LiNaPb2Br6 can be widely adjusted by continuously tuning the Eg of this superlattice. The calculated results demonstrate that the optical properties of LiNaPb2Br6 were optimized in comparison to APbBr3 (A = Li, Na). In addition, the increase in pressure improves the absorption capability of LiNaPb2Br6 in both the visible and ultraviolet regions, thereby expanding the potential applications of LiNaPb2Br6 in the optical field.