Typical Values Research Articles

Dosage optimization of tacrolimus based on the glucocorticoid dose and pharmacogenetics in adult patients with systemic lupus erythematosus

BackgroundThe purpose of the study was to develop a genotype-incorporated population pharmacokinetic (PPK) model of tacrolimus (TAC) in adults with systemic lupus erythematosus (SLE) to investigate the factors influencing TAC pharmacokinetics and to develop an individualized dosing regimen based on the model. In addition, a non-genotype-incorporated model was also established to assess its predictive performance compared to the genotype-incorporated model. MethodsA total of 365 trough concentrations from 133 adult SLE patients treated with TAC were collected to develop a genotype-incorporated PPK model and a non-genotype-incorporated PPK model of TAC using a nonlinear mixed-effects model (NONMEM). External validation of the two models was performed using data from an additional 29 patients. Goodness-of-fit diagnostic plots, bootstrap method, and normalized predictive distribution error test were used to validate the predictive performance and stability of the final models. The goodness-of-fit of the two final models was compared using the Akaike information criterion (AIC). The dosing regimen was optimized using Monte Carlo simulations based on the developed optimal model. ResultsThe typical value of the apparent clearance (CL/F) of TAC estimated in the final genotype-incorporated model was 14.3 L h−1 with inter-individual variability of 27.6%. CYP3A5 polymorphism and coadministered medication were significant factors affecting TAC-CL/F. CYP3A5 rs776746 GG genotype carriers had only 77.3% of the TAC-CL/F of AA or AG genotype carriers. Omeprazole reduced TAC-CL/F by 3.7 L h−1 when combined with TAC, while TAC-CL/F increased nonlinearly as glucocorticoid dose increased. Similar findings were demonstrated in the non-genotype-incorporated PPK model. Comparing these two models, the genotype-incorporated PPK model was superior to the non-genotype-incorporated PPK model (AIC = 643.19 vs. 657.425). Monte Carlo simulation based on the genotype-incorporated PPK model indicated that CYP3A5 rs776746 AA or AG genotype carriers required a 1/2–1 fold higher dose of TAC than GG genotype carriers to achieve the target concentration. And as the daily dose of prednisone increases, the dose of TAC required to reach the target concentration increases appropriately. ConclusionsWe developed the first pharmacogenetic-based PPK model of TAC in adult patients with SLE and proposed a dosing regimen based on glucocorticoid dose and CYP3A5 genotype according to the model, which could facilitate individualized dosing for TAC.

Ultrasound Detection of Fetal Palate Development in the Early Stages of the Second Trimester and Its Clinical Application.

To establish normal values of palatal bone growth in fetuses at different gestational weeks in the early stages of the second trimester and to explore the clinical application value of the four-step ultrasound screening method for fetal cleft lip and palate. A prospective study of prenatal ultrasound screening. Secondary maternal and child health institutions. 300 fetuses of 12 to 20 +6 weeks gestation without cleft lip and/or palate; 8538 fetuses at high risk of cleft lip and palate with malformations or karyotypic abnormalities. None. palatomandibular diameter (PMD) and transverse palatal diameter was measured and establish their typical values. (1) There is a typical "superimposed line" sign in the median sagittal section of the typically developing fetal face from 12 to 20+6 weeks of gestation. (2) The PMD and hard palate transverse diameter of fetuses from 12 to 20+6 weeks of gestation increased linearly with time. (3) Among 8538 high-risk fetuses, 21 cases of cleft lip and palate were diagnosed by the four-step ultrasound screening method in the early stages of the second trimester. The median sagittal section of the typically developing fetal face in the early stages of the second trimester presents a typical "superimposed line" sign, and the PMD and transverse palatal diameter increase with time. The four-step ultrasound screening method for fetal cleft lip and palate in the early stages of the second trimester has high clinical application value.

Magnetic Fields in Solar Plage Regions: Insights from High-sensitivity Spectropolarimetry

Plage regions are patches of concentrated magnetic field in the Sun’s atmosphere where hot coronal loops are rooted. While previous studies have shed light on the properties of plage magnetic fields in the photosphere, there are still challenges in measuring the overlying chromospheric magnetic fields, which are crucial to understanding the overall heating and dynamics. Here, we utilize high-sensitivity, spectropolarimetric data obtained by the 4 meter Daniel K. Inouye Solar Telescope to investigate the dynamic environment and magnetic field stratification of an extended, decaying plage region. The data show strong circular polarization signals in both plage cores and surrounding fibrils. Notably, weak linear polarization signals clearly differentiate between plage patches and the fibril canopy, where they are relatively stronger. Inversions of the Ca II 8542 Å spectra show an imprint of the fibrils in the chromospheric magnetic field, with typical field strength values ranging from ∼200 to 300 G in fibrils. We confirm the weak correlation between field strength and cooling rates in the lower chromosphere. Additionally, we observe supersonic downflows and strong velocity gradients in the plage periphery, indicating dynamical processes occurring in the chromosphere. These findings contribute to our understanding of the magnetic field and dynamics within plages, emphasizing the need for further research to explore the expansion of magnetic fields with height and the three-dimensional distribution of heating rates in the lower chromosphere.

Dust giant: Extended and clumpy star-formation in a massive dusty galaxy at z = 1.38

We present NOEMA CO (2–1) line and ALMA 870 µm continuum observations of a main-sequence galaxy at z = 1.38. The galaxy was initially deemed a “gas giant” based on the gas mass derived from sub-mm continuum (log(Mgas/M⊙) = 11.20 ± 0.20), however, the gas mass derived from CO (2−1) luminosity brings the gas mass value down to a level that is consistent with typical values for star-forming galaxies at that redshift (log(Mgas/M⊙) = 10.84 ± 0.03). Meanwhile, the dust-to-stellar mass ratio remains elevated above the scaling relations by a factor of 5. In this work, we explore the potential physical picture and consider an underestimated stellar mass and optically thick dust as possible explanations. Based on the updated gas-to-stellar mass ratio, we can rule out the former; while the latter may indeed contribute to the overestimation of the dust mass, it is not sufficient enough to explain the observed physical picture overall. Instead, other plausible explanations include enhanced HI reservoirs, an unusually high metallicity, or the presence of an optically dark, dusty contaminant. Using the ALMA data at 870 µm coupled with HST/ACS imaging, we find an extended morphology in dust continuum and clumpy star-formation in rest-frame UV in this galaxy. In addition, a tentative ~10 kpc dusty arm is found to be bridging the galaxy center and a clump in F814W image. The galaxy shows levels of dust obscuration similar to the so-called HST-dark galaxies at higher redshifts, thus falling into the optically faint and dark JWST color-color selection at z > 2. It is therefore possible that our object may stand as a low-z analog of the HST-dark populations. This galaxy serves as a caveat to the gas masses based on the continuum alone, with a larger sample required to unveil the full picture.

Fabrication of silver nanoparticle-containing electrospun polycaprolactone membrane coated with chitosan oligosaccharides for skin wound care

An ideal wound dressing should have several qualities to protect the wound from infection and other adverse factors. This study aimed to fabricate a wound care membrane combining the two well-known bioactive agents silver nanoparticles (AgNPs) and chitosan oligosaccharides (COS). In specific, this multilayer membrane (PCL-Ag/POX/COS) consisted of (1) the electrospun basement layer of poly(ε-caprolactone) (PCL) and AgNPs; (2) the intermediate amphiphilic layer of PCL and poloxamer 407 (POX); and (3) the coating layer of COS and poly(N-vinyl pyrrolidone) (PVP). Several characterisation tests showed that the membrane was successfully coated with COS and owned suitable characteristics as a wound dressing, including proper tensile strength (more significant than the typical value of the skin), the hydrophilic and fluid-absorbable innermost surface, the waterproof outermost basement, vapour permeability, rapid COS release, and gradual AgNP release. In vitro experiments proved its haemostatic effect and antibacterial activities. Though its 100% extract solution reduced in vitro fibroblast viability, through the skin-defected mouse model experiment, PCL-Ag/POX/COS was compatible with the wound tissue and exhibited several positive effects on wound healing. In conclusion, PCL-Ag/POX/COS was proven for its potential for wound care, but it needs further investigations to allow translation from bench to bedside.

Investigation into the reflection properties of the neutron star low-mass X-ray binary 4U 1636–53

We present the spectroscopy of the neutron star low-mass X-ray binary 4U 1636–53 using six simultaneous XMM-Newton and Rossi X-ray Timing Explorer observations. We applied different self-consistent reflection models to explore the features when the disk is illuminated by either the corona or the neutron star surface. We found that the spectra could be well fitted by these two types of models, with the derived emissivity index below a typical value of 3. The relative low emissivity can be explained if the neutron star and the corona, working together as an extended illuminator, simultaneously illuminate and ionize the disk. Additionally, the derived ionization parameter in the lamppost geometry is larger than the theoretical prediction. This inconsistency likely suggests that the corona does not emit isotropically in a realistic context. Furthermore, we also found that there is a possible trend between the height of the corona and the normalization of the disk emission. This could be understood either as a variation in the reflected radiation pressure or in the context of a jet base. Finally, we found that the disk is less ionized if it is illuminated by the neutron star, indicating that the illuminating source has significant influence on the physical properties of the disk.

Permittivity from first principles

Dielectric properties of materials are generally introduced phenomenologically through empirical values of permittivity. While this approach is necessary for practical work, it must be recognized that it bypasses the question of whether it is possible to predict permittivity values from first principles and thus get a deeper grasp of the physics involved in bridging the microscopic system and its macroscopic properties. Theoretical frameworks to gain insight and to compute exactly permittivity values are desirable to understand the nuances that go into building this bridge. We introduce here such a theoretical model system to gain physical intuition on the microscopic origin of the permittivity. The system consists of electrons in a one-dimensional atomic chain in the presence of an external electric field, where each atom is a binding site. We first consider a single atom in an external field to study atomic polarization, justify the model, tune the parameters, and compare with perturbative approaches. We then consider the assembly of many such atoms in a periodic arrangement and study its band-structure, including explicitly the external electric field. Last, within this model we develop explicit formulas for the permittivity in terms of relevant physical parameters. Finally, we obtain a numerically value for the permittivity of the system for typical values of binding energy and electric field.

Effective medium temperature for calculating the deformed Doppler broadening function considering the Tsallis distribution

This paper presents a method for establishing an equivalence relationship between the Doppler Broadening Function based on the Maxwell-Boltzmann Distribution and the Deformed Doppler Broadening Function, according to the generalised Tsallis Distribution, through an effective temperature Teff of the medium. The proposed method allows a precise calculation of the Maxwellian Doppler Broadening Function, which reproduces the value of the Tsallis Doppler Broadening Function (TDBF), where ξ is associated to the temperature of medium T and ξ∼q relates to the effective temperature Teff of the medium. In this paper, we calculate ξ∼q for typical values of the deformation factor q together with a parameterization example for ξ∼q as a result of the ordered pair x,ξ, using a genetic algorithm technique. The results obtained were accurate, with a percentage deviation under 2%.

Millimeter-wave noise generation based on a monolithically integrated dual-mode chaotic laser.

A millimeter-wave noise generation scheme is proposed in this paper. The scheme is based on a monolithically integrated dual-mode chaotic laser, which consists of a distributed Bragg feedback (DFB) section, a phase section, and an optical amplification section. The output spectrum state of the dual-mode laser can be controlled by adjusting the injection current in the three regions. The monolithically integrated dual-mode chaotic laser has stable chaotic output and can be used as a light source for integrated millimeter-wave noise source. As a feasibility demonstration, a dual-mode chaotic laser with a mode interval of 2.05 nm was generated in the experiment, the optical mixing on a photodetector produced millimeter-wave noise with a center frequency of 259 GHz and a bandwidth of 44 GHz (237-281 GHz), achieving a typical value of excess noise ratio of 47 dB. It has the advantages of high noise source utilization, small noise source volume, and high integration.

Spectroscopic substellar initial mass function of NGC 2244

Context. The dominant formation channel of brown dwarfs (BDs) is not well constrained yet and a promising way to discriminate between scenarios is to test the environment-dependent efficiency in forming BDs. So far, the outcome of star formation, studied through the initial mass function, has been found to be very similar in all clusters that have been inspected. Aims. We aim to characterize the low-mass (sub)stellar population of the central portion (2.4 pc2) of the ∼2 Myr old cluster NGC 2244 using near-infrared spectroscopy. By studying this cluster, characterized by a low stellar density and numerous OB stars, we aim to explore the effect that OB stars may have on the production of BDs. Methods. We obtained near-infrared HK spectroscopy of 85 faint candidate members of NGC 2244. We derived the spectral type and extinction by comparison with spectral templates. We evaluated cluster membership using three gravity-sensitive spectral indices based on the shape of the H-band. Furthermore, we evaluated the infrared excess from Spitzer of all the candidate members of the cluster. Finally, we estimated the mass of all the candidate members of the cluster and derived the initial mass function, star-to-BD number ratio, and disk fraction. Results. The initial mass function is well represented by a power law (dN/dM ∝ M−α) below 0.4 M⊙, with a slope α = 0.7–1.1 depending on the fitted mass range. We calculated a star-to-BD number ratio of 2.2–2.8. We find the low-mass population of NGC 2244 to be consistent with nearby star-forming regions, although it is at the high end of BD production. We find BDs in NGC 2244 to be, on average, closer to OB stars than to low-mass stars, which could potentially be the first piece of evidence that OB stars affect the formation of BDs. We find a disk fraction of all the members with a spectral type later than K0 of 39 ± 9% which is lower than typical values found in nearby star-forming regions of similar ages.

(Invited) III-V Integration on Silicon for Resource-Efficient Sensor-Technology

This work deals with the wafer-level integration of advanced group III-V devices and integrated circuits on silicon substrate for RF-sensor integration, such as radar functions a very high frequencies beyond 300 GHz [1]. The aim is to achieve both performance improvements on device level, co-integration with digital functions, and advanced integration to achieve a greener usage of material critical to the environment. Submillimeter-Wave frequency bands beyond 300 GHz allow for broadband transmit and receive windows, serviceable to both communications and radar-based applications—increasing data rates and imaging resolutions, respectively. On the other hand, CMOS co-integration is called for by the data acquisition- and other mixed-mode- and fast digital functions. As examples of the integration schemes Terahertz Monolithic Integrated Circuit amplifiers (TMICs) are implemented in an advanced transferred-substrate InGaAs-channel HEMT technology with 20-nm gate length on silicon. The inverted III-V HEMT heterostructure is grown by molecular beam epitaxy (MBE) on 100-mm semi-isolating GaAs wafers and transferred to silicon substrates by using a SiO2-based wafer bond process with subsequent wafer thinning and removal of the GaAs substrate. Thus, only a 100-nm-thick III-V heterostructure layer is remaining on the Si substrate. This advanced transferred-substrate technology also offers the implementation of HEMT devices with backside gate [2,3] to achieve better sub-threshold slope, or field plates to increase both channel confinement and higher breakdown voltages. The 20-nm InGaAs-OI HEMT technology features typical values for the OFF-state breakdown voltage of 5 V and and maximum drain-current density of 1200 mA/mm, respectively. A maximum transconductance of 2400 mS/mm is achieved. The expected cutoff frequency values fT and fmax are above 500 GHz and 1 THz, respectively [4]. A fully passivated back-end-of-line (BEOL) process is used, including three metal layers (MET1–MET3). A NiCr 50 Ohm sq thin-film-resistor layer, as well as an SiN layer for the implementation of MIM capacitors between MET2 andMET3. S-parameter characteristics of a six-stage and nine-stage TMIC amplifiers in the frequency band from 620 to 730 GHz are given as examples. During the on-wafer characterization, the HEMT devices in cascode configuration have been biased at VD= 2 V (1 V drain–source voltage per device) and a current of 350 mA/mm. The measured small-signal gain of the six-stage cascode TMIC amplifier is in the range of 22–25 dB over the frequency range from 670 to above 700 GHz. This corresponds to 4 dB of gain per cascode stage around the 670-GHz frequency range. A nine-stage TMIC amplifier, on the other hand, achieves at least 30 dB of measured gain from 660 to about 700 GHz. This again corresponds to a gain per stage below 4 dB. Such results prove both the advancements in integration as well as state-of-the-art circuit performance co-integrated on silicon.

(Invited) The Reservoir Effect: When Capacity Measurements Cannot Track Cell Aging

The initial capacity that is provided by a Li-ion battery is limited by the amount of Li+ that is supplied by the cathode. During the life of a cell, growth of the solid electrolyte interphase (SEI) will slowly consume Li+, which generally leads to capacity fade. Capacity and coulombic efficiency measurements are commonly used in battery research to quantify the evolution of SEI growth. In this talk, we show that, in reality, such measurements can often be unreliable sources of information about the extent of aging endured by the cell.[1,2] A core problem with relying on capacity measurements to track aging is that they may not probe all the Li+ that is present in the cell. See for example Figure 1a, which shows the voltage profiles of three types of anodes (graphite, silicon-graphite and SiOx) during the discharge of a full-cell. At the end of discharge, we assume that all anodes will experience a same potential of 0.6 V vs Li/Li+, which is the point in which the profiles intersect in the figure. Portions of the voltage profiles to the right of this point of intersection indicate Li+ that will remain in the anode even after the cell is “fully” discharged. That is, Li+ that was inserted into the anode during the initial charge, but that cannot be recovered at the voltage cutoff selected for cell discharge. The magnitude of this “reservoir” of Li+ depends on the shape of the voltage profile of the anode at high potentials. Failure to account for the existence of this reservoir will, for example, distort estimates about the initial Li+ consumption to form the SEI. To make matters worse, capacity stored in this Li+ reservoir can slowly be accessed as the cell ages, blurring the correlation between capacity measurements and SEI growth. During cell charging, most cathode materials of commercial interest will experience an increase in potential as they delithiate (Figure 1b). If some of that Li+ is consumed at the SEI, then the cathode cannot be restored to its original state of lithiation once the cell is fully discharged. In other words, aging will cause the cathode to experience increasing potentials once the cell meets the discharge cutoff voltage. Assuming that voltage cutoffs are constant for all cycles, an increase in cathode potential by ΔU would prompt an equal increase in the potential of the anode. A key consequence is that this bump in potential will lead to partial delithiation of the Li+ reservoir stored in the anode, releasing “extra” Li+ that can go back into the cathode. Accessing this extra capacity will offset some of the measurable Li+ losses to the SEI. Since the size of this reservoir is larger in Si than in graphite, capacity measurements in silicon cells can largely underestimate the true extent of SEI growth, and may conceal relatively high levels of cell aging under the appearance of satisfactory cycling performance. The example above shows that the reliability of using capacity measurements for conveying information about aging depends on the anode used in the cell. This same general behavior can also arise when comparing different cathode materials, or even different operating conditions (such as cycling rate and depth of discharge) for a same type of battery. This talk will discuss some of these cases, and how they can affect the diagnostic of aging in Li-ion cells.Figure 1. a) Assumed voltage profiles for anodes during the discharge of hypothetical full-cells. At the discharge cutoff voltage, all anodes will initially experience a typical value of ~0.6 V vs. Li/Li+ (indicated by the intersection point). Regions to the right of that point indicate capacity that remains stored at the anode even when the full-cell is nominally fully discharged. b) Example of successive charge and discharge half-cycles in a NMC811 cathode. The solid black line indicates portions of the voltage profile that are actively utilized in the cathode. When Li+ is lost to the SEI, the cathode cannot be restored to the Li+ content it exhibited at the beginning of charge, leading to an increase in cathode potential when the full-cell reaches the cutoff voltage.

Population Pharmacokinetic Analysis of Follicle-Stimulating Hormone During Ovarian Stimulation: Relation with Weight, Prolactin and Gene Polymorphism in THADA and ADIPOQ.

Personalisation strategies of ovarian stimulation for in vitro fertilisation (IVF)/ intracytoplasmic sperm injection (ICSI) treatments using exogenous follicle-stimulating hormone (FSH) have been extensively studied over the past 20 years. This research aimed to develop a FSH population pharmacokinetic (PPK) model taking into account the contribution of gene polymorphisms in Chinese reproductive-age women. Data from 173 patients undergoing GnRH agonist down-regulation long protocols of IVF/ICSI treatment were collected. PPK analysis was subsequently conducted using the nonlinear mixed-effect model (NONMEM) software. Several covariates, including 18 single nucleotide polymorphisms, demographic factors and biological characteristics, were evaluated. The final PPK model was extensively validated using bootstrapping and normalised prediction error distribution, as well as external validation on an independent group of 35 patients. FSH PPK was accurately described by a one-compartment model with first-order absorption. The typical population value of apparent clearance was estimated to be 0.81 L/h [relative standard errors (RSE) 5.3%] with an inter-individual variability (IIV) of 16.0%. The typical apparent distribution volume was 8.36 L (RSE 9.7%, 59.7% IIV), and the absorption rate constant was estimated to be 0.0444 h-1 (RSE 9.1%). Body weight, basal prolactin concentration and the gene ADIPOQ (rs1501299) showed a significant covariate effect on the FSH clearance rate and exposure concentration. Genotypes of THADA (rs12478601) significantly influenced the distribution volume. Simulation results indicated that patients with the TT genotype of THADA (rs12478601) required a longer time to reach steady state and had less fluctuation in FSH levels. Model evaluations showed that the final model accurately and precisely described the observed data and demonstrated effective prediction performance. PPK models of FSH have been developed, which could potentially be used for FSH dosage individualisation in the clinical setting. This study has been registered with the Chinese Clinical Trials Registry (ChiCTR2100049142).

Effect of Fabric Areal Weight on the Mechanical Properties of Composite Laminates in Carbon-Fiber-Reinforced Polymers

The present work aims at studying the effect of the reinforcing fabric areal weight on the mechanical properties of composite laminates in carbon-fiber-reinforced polymers. Three different pre-impregnated 2 × 2 twill weaves, characterized by the different areal weight values of 380, 630, and 800 g/m2 were used to produce laminates. These areal weights were selected to represent typical values used in structural application. A hand lay-up technique followed by an autoclave cycle curing was employed to produce the laminates. The desired final thickness of the laminates was obtained by laying-up a different ply number, as a function of the areal weight and thickness of each fabric. Uniaxial tensile and in-plane shear response tests were performed on samples obtained from laminates after curing. Furthermore, the presence of voids in composite materials were detected by performing resin digestion tests. Finally, light optical microscopy and stereomicroscopy analyses allowed observing the different arrangement of the plies in the cross-sections of laminates after curing and evaluating the degree of compaction as a function of the reinforcing fabric used. It was demonstrated that the fabric areal weight significantly affects the mechanical performances of the composite laminates; specifically, the decrease in the areal weight of the twill weave leads to an increase in tensile strength, elastic modulus, and in-plane shear stress, i.e., of about 56.9%, 26.6%, and 55.4%, respectively, if 380 g/m2 and 800 g/m2 fabrics are compared. These results are crucial for an optimal material selection during the design process for industrial applications and help to better understand composite material behavior.

Photoexcited Carrier Transfer in CuInS2 Nanocrystal Assembly by Suppressing Resonant-Energy Transfer.

High-density assemblies or superlattice structures composed of colloidal semiconductor nanocrystals have attracted attention as key materials for next-generation photoelectric conversion devices such as quantum-dot solar cells. In these nanocrystal solids, unique transport and optical phenomena occur due to quantum coupling of localized energy states, charge-carrier hopping, and electromagnetic interactions among closely arranged nanocrystals. In particular, the photoexcited carrier dynamics in nanocrystal solids is important because it significantly affects various device parameters. In this study, we report the photoexcited carrier dynamics in a solid film of CuInS2 nanocrystals, which is one of the potential nontoxic substitutes with Cd- and Pb-free compositions. Meanwhile, these subjects have been extensively studied in nanocrystal solids formed by CdSe and PbS systems. A carrier-hopping mechanism was confirmed using temperature-dependent photoluminescence spectroscopy, which yielded a typical value of the photoexcited carrier-transfer rate of (2.2±0.6)×107 s-1 by suppressing the influence of the excitation-energy transfer.

Collapse caldera walls: Mechanical controls on slope failure and morphology

Volcanic calderas are enclosed topographic depressions that are commonly delimited by steep annular cliffs (caldera walls). The walls represent degraded scarps of ring faults that accommodated caldera collapse. Here, we assess the mechanical controls on caldera wall morphology and failure by: (i) analysing slope properties of recently formed calderas; (ii) examining analytical solutions for slope failure; and (iii) simulating progressive slope failure via Distinct Element Method (DEM) numerical modelling. Average slope angles of the caldera walls in nature range from 20° to 65° and slope heights range from 99 m to 1080 m. Smaller slope heights are weakly tied to greater slope inclinations. Almost 60% of sampled caldera wall profiles show a steeper upper section and a gentler lower section, which in numerical models are reproduced as an upper slope comprising intact wall rock and a lower slope comprising failed material inclined at the angle of repose. Moreover, modelled material with a low angle of internal friction and low cohesion exhibits shear failure, whereas material with high friction and high cohesion shows tension cracking, buckling and toppling. The slope height and inclination data from the numerical models agree well with those in nature. The numerical model data correspond more closely to analytically-predicted failure planes than critical (i.e. limit equilibrium) slopes because they are short-lived and therefore unlikely to be sampled in either model or nature. If rock mass cohesions or friction angles constrained analytically from natural slopes are determined by assuming the slope is critical, they are likely to be underestimates. The homogeneous numerical models here give an estimated natural rock mass cohesion of 0.5 MPa or less. This is much lower than typical laboratory-scale cohesion values, and it highlights the importance of strength reduction when upscaling mechanical parameters from laboratory experiments for modelling slope stability and volcano deformation.

Establishment of diagnostic reference levels in computed tomography in two large hospitals in Oman.

This study aimed to estimate diagnostic reference levels (DRLs) for the most frequent computed tomography (CT) imaging examinations to monitor and better control radiation doses delivered to patients. Seven CT imaging examinations: Head, Chest, Chest High Resolution (CHR), Abdomen Pelvis (AP), Chest Abdomen Pelvis (CAP), Kidneys Ureters Bladder (KUB) and Cardiac, were considered. CT dosimetric quantities and patient demographics were collected from data storage systems. Local typical values for DRLs were calculated for CTDIvol (mGy), dose length product (DLP) (mGy·cm) and effective doses (mSv) were estimated for each examination. The calculated DRLs were given as (median CTDIvol (mGy):median DLP (mGy·cm)): Head: 39:657; Chest: 13:451; CHR: 6:228; AP: 12:578; CAP: 20:807; KUB: 7:315, and Cardiac: 2:31. Estimated effective doses for Head, Chest, CHR, AP, CAP, KUB and Cardiac were 1.3, 12.7, 6.3, 12.5, 18.1, 5.8 and 0.8mSv, respectively. The estimated DRLs will act as guidance doses to prevent systematic excess of patient doses.

Structure and Conformation of Hydroxypropylmethyl Cellulose with a Wide Range of Molar Masses in Aqueous Solution─Effects of Hydroxypropyl Group Addition.

The structure of hydroxypropylmethyl cellulose (HpMC) samples with a wide range of weight average molar masses (Mw) from 23 to 5000 kg mol-1, a controlled degree of substitution (DS) of 1.9 by methyl groups, and a molar substitution number (MS) of 0.25 by hydroxypropyl groups dissolved in aqueous solution was examined using static light scattering (SLS), dynamic light scattering (DLS), small-to-wide angle neutron scattering (S-WANS) techniques, and intrinsic viscosity ([η]) measurements. The determined Mw and the radius of gyration (Rg) showed the relationships Rg ∝ Mw1.0 and [η] ∝ Mw1.7 in a range of Mw < 100 kg mol-1, similar to rigid rod molecules in solution. However, exponents in the relationships decreased gradually with increasing Mw and reached ∼0.5 in a high Mw region, which is a typical value of flexible chain molecules for both Rg and [η]. These observations suggest that the HpMC samples behave as semiflexible rods with a certain persistence length (lp). The ratios of the hydrodynamic radius via DLS measurements to Rg also supported semiflexible rod behavior. Particle form factors and the average lengths (L) resulting from SLS and S-WANS experiments are well described with rigid rod particles in the range of Mw < 100 kg mol-1 and semiflexible rods with lp ∼ 100 nm in Mw > 100 kg mol-1. Because the average contour length (lc) calculated from Mw is approximately twice as long as L in the Mw range < 100 kg mol-1, the formed HpMC particles possess a folded hairpin-like elongated rigid rod structure. However, the lc/L value increases gradually in the range Mw > 200 kg mol-1, where the formed HpMC particles behave as semiflexible rods. The formed particle structure was substantially different from that found in methyl cellulose samples with a similar DS value, which showed rod-like behavior over a wide Mw range. The addition of hydroxypropyl groups only at MS = 0.25 effectively changed the formed particle structure.

How does the chromatic number of a random graph vary?

AbstractThe chromatic number of a graph is a fundamental parameter, whose study was originally motivated by applications ( is the minimum number of internally compatible groups the vertices can be divided into, if the edges represent incompatibility). As with other graph parameters, it is also studied from a purely theoretical point of view, and here a key question is: what is its typical value? More precisely, how does , the chromatic number of a graph chosen uniformly at random from all graphs on vertices, behave? This quantity is a random variable, so one can ask (i) for upper and lower bounds on its typical values, and (ii) for bounds on how much it varies: what is the width (for example, standard deviation) of its distribution? On (i) there has been considerable progress over the last 45 years; on (ii), which is our focus here, remarkably little. One would like both upper and lower bounds on the width of the distribution, and ideally a description of the (appropriately scaled) limiting distribution. There is a well‐known upper bound of Shamir and Spencer of order , improved slightly by Alon to , but no non‐trivial lower bound was known until 2019, when the first author proved that the width is at least for infinitely many , answering a longstanding question of Bollobás. In this paper we have two main aims: first, we shall prove a much stronger lower bound on the width. We shall show unconditionally that, for some values of , the width is at least , matching the upper bounds up to the error term. Moreover, conditional on a recently announced sharper explicit estimate for the chromatic number, we improve the lower bound to order , within a logarithmic factor of the upper bound. Second, we will describe a number of conjectures as to what the true behaviour of the variation in is, and why. The first form of this conjecture arises from recent work of Bollobás, Heckel, Morris, Panagiotou, Riordan and Smith. We will also give much more detailed conjectures, suggesting that the true width, for the worst case , matches our lower bound up to a constant factor. These conjectures also predict a Gaussian limiting distribution.

High pressure and high temperature phase transformations of covalent triazine-based frameworks

A monolithic two-dimensional (2D) biphenyl-linked triazine-based framework (CTF-2) showing merely slight crystallinity was prepared by Lewis acid-promoted polymerisation of 4,4′-biphenyldicarbonitrile in liquid TiCl4 at moderate temperature to avoid unwanted carbonization. The transformations of CTF-2 induced by high pressure (up to 60 GPa) and temperature (up to 2400 K) were studied by IR and in situ Raman spectroscopy as well as TEM microscopy. In contrast to graphitic C3N4 materials, CTF-2 exhibits high optical density and reduced fluorescence at high pressure, allowing laser-induced sample heating. Spectral data show the formation of sp3 hybridised carbon atoms and triazine ring distortion in CTF-2 material at pressures above 17 GPa. According to the pressure Raman effect, the bulk modulus of the high-pressure phase of CTF-2 (high-pressure phase CTF-2) was found to be 570 ± 10 GPa, which is a typical value for superhard carbon materials. Structural studies revealed nitrogen preservation in the specimen after high-pressure treatment and stability of the disordered sp3 states of the high-pressure phase CTF-2 in the quenched specimen. This behaviour is quite different from that of the quenched disordered sp3 states of high pressure pure carbon phases, which convert to the sp2 state at pressures below 3–7 GPa.