Determination Of Density Research Articles

Time-resolved photoluminescence: a precision tool for shallow trap density determination in perovskite films

Time-resolved photoluminescence: a precision tool for shallow trap density determination in perovskite films

Accessing the free expansion of a crystalline colloidal drop by optical experiments.

We study poly-crystalline spherical drops of an aqueous suspension of highly charged colloidal spheres exposed to a colloid-free aqueous environment. Crystal contours were obtained from standard optical imaging. The crystal spheres first expand to nearly four times their initial volume before slowly shrinking due to dilution-induced melting. Exploiting coherent multiple-scattering by (110) Bragg reflecting crystals, time-dependent density profiles were recorded within the drop interior. These show a continuously flattening radial density gradient and a decreasing central density. Expansion curves and density profiles are qualitatively consistent with theoretical expectations based on dynamical density functional theory for the expansion of a spherical crystallite made of charged Brownian spheres. We anticipate that our study opens novel experimental access to density determination in turbid crystals.

Development of Auto Dense-breast Classification on Mammography Images Using Image Similarity

In Japan, radiologists perform qualitative visual classification to define four categories of mammary gland density. However, an objective estimation of mammary gland density is necessary. To address this, we developed an automatic classification software using image similarity. We prepared 741 cases of mediolateral oblique images (MLO) for evaluation, and they were diagnosed as normal among the mammography images taken at our hospital. Image matching was performed using the evaluation images and an image database for breast density determination. In this study, the image similarity used zero normalized cross-correlation (ZNCC) as an index. In addition, if the breast thickness is less than 30 mm and each breast density category ZNNC has the same value, the category is evaluated on the fat side. We compared the results of qualitative visual classification and automatic classification methods to assess consistency. The agreement with the subjective breast composition classification was 78.5%, and the weighted kappa coefficient was 0.98. One mismatched case was evaluated on the higher density side with the same ZNCC value between categories and a breast thickness greater than 30 mm. Image similarity provides an excellent estimation of quantification of breast density. This system could contribute to improving the efficiency of the mammography screening system.

Determination of physical properties of siamese oranges (Citrus nobilis var. Microcarpa): sphericity, roundness, volume, and density

Siamese oranges are a member of the tangerines which have the scientific name Citrus nobilis var.Microcarpa. It is called Siamese orange because it comes from Siam (Muangthai). The quality of Siamese oranges is determined by their physical properties. These physical properties include size, weight, volume and diameter. Post-harvest technology for Siamese oranges can be done by grading to obtain quality Siamese oranges according to standards. This research aims to determine the physical properties of Siamese oranges used in the grading process. Determination of sphericity and roundness is measured using a caliper. Determination of volume and density is measured using a beaker. Analysis of research data used a one-way z-test normal distribution to the left. The results of data analysis show that the z-count value of roundness, roundness, volume and density is 1.05; 0.79; 0.55; 0.53 and -ztable of -1.645. This means zcount ≥ -ztable, where the average value of the physical properties of Siamese oranges is greater than or equal to the research object, roundness is 0.92, roundness is 0.93, volume is 87 cm3 and density is 1.02 g/ cm3. Thus, the results of these physical properties can be used as a reference when grading Siamese oranges code size 2.

Experimental characterization of defect-induced Raman spectroscopy in graphene with BN, ZnO, Al2O3, and TiO2 dopants

The introduction of boron nitride (BN), zinc oxide (ZnO), aluminum oxide (Al2O3), and titanium oxide (TiO2) as dopants in pristine graphene leads to the modification of its transport properties, resulting in the production of graphene semiconductors and alteration of its semiconductive characteristics. The achievement of high-quality electronic devices necessitates considering doping and producing a broader energy bandgap in graphene. The optical determination of charge density in intrinsic graphene may be achieved by utilizing the D Raman peak, where an increased charge density is associated with a decreasing peak split. Strong connections have been seen between the energy bandgap (Eg) and the locations of the G and D peaks. Various doping materials exhibit distinct variations and effects on the doping process of graphene. The determination of doping levels in graphene may be achieved with far greater accuracy by observing the ID/IG ratios, compared to the traditional method of measuring the G-band shift with charge. The determination of average crystallite size, as well as the observation of the parameter La, is crucial in comprehending the doping and flaws present in graphene materials that have been manufactured.

The osteoporosis susceptibility SNP rs188303909 at 2q14.2 regulates EN1 expression by modulating DNA methylation and E2F6 binding.

EN1 encodes a homeodomain-containing transcription factor and is a determinant of bone density and fracture. Previous powerful genome-wide association studies (GWASs) have identified multiple single-nucleotide polymorphisms (SNPs) near EN1 at 2q14.2 locus for osteoporosis, but the causal SNPs and functional mechanisms underlying these associations are poorly understood. The target genes regulated by the transcription factor EN1 are also unclear. In this study, we identified rs188303909, a functional CpG-SNP, as a causal SNP for osteoporosis at 2q14.2 through the integration of functional and epigenomic analyses. Functional experiments demonstrated that unmethylated rs188303909 acted as a strong allele-specific distal enhancer to regulate EN1 expression by modifying the binding of transcription factor E2F6, but rs188303909 methylation attenuated the active effect of E2F6 on EN1 expression. Importantly, transcription factor EN1 could differentially bind osteoporosis GWAS lead SNPs rs4869739-T and rs4355801-G to upregulate CCDC170 and COLEC10 expression, thus promoting bone formation. Our study provided a mechanistic insight into expression regulation of the osteoporosis susceptibility gene EN1, which could be a potential therapeutic target for osteoporosis precision medicine. KEY MESSAGES: CpG-SNP rs188303909 is a causal SNP at the osteoporosis susceptibility locus 2q14.2. Rs188303909 distally regulatesEN1expression by modulating DNA methylation and E2F6 binding. EN1 upregulatesCCDC170 and COLEC10expression through osteoporosis GWAS lead SNPs rs4869739 and rs4355801.

Discrimination of Hemorrhage and Contrast Media in a Head Phantom on Photon-Counting Detector CT Data.

In this anthropomorphic head phantom study, samples containing blood and contrast agent with concentrations ranging from 0 to 6 mg iodine per milliliter and another set of samples without blood for reference were scanned with a photon-counting detector CT using a standard cranial protocol. It was demonstrated that photon-counting detector CT can reliably distinguish hemorrhage and contrast media, including density determination of the latter. The technology promises to add value in several neuroimaging applications.

Liposomes as a carrier for 4–hydroxycoumarin: characterisation, stability and antioxidant potential

<p>The aims of the present research were to develop and characterize 4-hydroxycoumarin-loaded liposomes <em>via </em>the determination of encapsulation efficiency, antioxidant capacity, vesicle size, polydispersity index (PDI), zeta potential, conductivity, mobility, density, surface tension, viscosity, and 60-day storage stability. The encapsulation efficiency of 4-hydroxycoumarin in liposomal particles was 96.7 ± 1.2%. The ABTS and DPPH radical scavenging capacity of the prepared liposomes was 89.76 ± 0.56% and 93.18 ± 0.23%, respectively, whereas cupric ion-reducing antioxidant capacity amounted to 0.367 ± 0.003 mmol Trolox equivalent (TE)/L. The density of liposomes with 4-hydroxycoumarin was 1.007 ± 0.002 g/cm<sup>3</sup>, surface tension was 22.7 ± 0.2 mN/m, and viscosity was 14.3 ± 0.2 mPa·s. Vesicle size and PDI of 4-hydroxycoumarin-loaded liposomes were changed from 1286.3 ± 73.8 nm to 2077.3 ± 63.2 nm and from 0.409 ± 0.050 to 0.676 ± 0.064, respectively, during the 60-day stability study. The zeta potential of the obtained liposomes was changed from -16.73 ± 0.47 mV to -10.31 ± 0.42 mV, while mobility varied from -1.311 ± 0.036 µmcm/Vs to -0.806 ± 0.031 µmcm/Vs. The conductivity did not change during 60 days and amounted to approximately 0.020 mS/cm. Overall, due to the high encapsulation efficiency and antioxidant capacity, the obtained results qualify liposomes to be used as 4-hydroxycoumarin carriers for future examination of its biological activities and potential application in medicine and pharmaceutical products. However, future experiments should include the optimization of the liposomal composition with the aim of improving 4-hydroxycoumarin-loaded liposome stability.</p>

Analysis of the dynamic response of a base isolated building during an earthquake with an intensity of 7 points on the MSK-64 scale

Introduction. The problem is considered and the relevance of studying the behavior of buildings and structures with seismic isolation systems using lead rubber bearing under real seismic impact, as well as assessing their technical condition after the earthquake, is emphasized. The experience of studying the behavior of base isolated buildings under real seismic impact abroad and in Russia is given.
 Materials and methods. The dynamic parameters seismic isolation of a reinforced concrete building using lead rubber bearing are investigated. Registration of seismic vibrations of the building was performed by a stationary station for dynamic monitoring. The results of processing the records were obtained based on the interpretation of monitoring data, including harmonic analysis, determination of the power spectral density, as well as the application of wavelet transform methods.
 Results. The results of dynamic monitoring of a base isolated building of a sea terminal located in Petropavlovsk-Kamchatsky city during an earthquake of 04/03/2023 with a magnitude of Mw =6.6 and an intensity at the site of the building equal to 7 points on the MSK-64 scale are presented. An analysis of the response and dynamic parameters of the building was performed, as well as a visual inspection of structures, as well as the building's seismic isolation systems.
 Conclusions. Analysis of the dynamic monitoring results made it possible to identify the natural vibration frequencies of the building, as well as to trace their changes during seismic impact. The maximum displacements of the building indicate minor shear deformations of the lead rubber bearing corresponding to the zone of their elastic operation. Both the rigidity of lead rubber bearing and the dynamic parameters of the building (frequencies (periods) of natural vibrations and the logarithmic damping decrement of the building) change depending on the intensity of the seismic impact and the shear deformation of the bearings, respectively. After the earthquake, widespread cracks and peeling of the plaster wall were observed with partial exposure of the layer of insulating material in the zone of filling with elastic elements the gaps between the strapping beams of the seismic isolation system and the structures of the building partitions at the level of the seismic isolating layer, which did not affect the operational reliability of the building. The study presented in this article shows that with the help of dynamic monitoring of buildings and structures, one can get a more complete and detailed understanding of their dynamic behavior, identify damage in the structural system of a building, and detect their undesirable or specific reactions that could not be taken into account when designing.

A comparison study between the realistic random modeling and simplified porous medium for gamma-gamma well-logging

The accurate determination of formation density and the physical properties of rocks is the most critical logging tasks which can be obtained using gamma-ray transport and detection tools. Though the simulation works published so far have considerably improved the knowledge of the parameters that govern the responses of the detectors in these tools, recent studies have found considerable differences between the results of using a conventional model of a homogeneous mixture of formation and fluid and an inhomogeneous fractured medium. It has increased concerns about the importance of the complexity of the model used for the medium in simulation works. In the present study, we have suggested two various models for the flow of the fluid in porous media and fractured rock to be used for logging purposes. For a typical gamma-gamma logging tool containing a 137Cs source and two NaI detectors, simulated by using the MCNPX code, a simplified porous (SP) model in which the formation is filled with elongated rectangular cubes loaded with either mineral material or oil was investigated. In this model, the oil directly reaches the top of the medium and the connection between the pores is not guaranteed. In the other model, the medium is a large 3-D matrix of 1 cm3 randomly filled cubes. The designed algorithm to fill the matrix sites is so that this realistic random (RR) model provides the continuum growth of oil flow in various disordered directions and, therefore, fulfills the concerns about modeling the rock textures consist of extremely complex pore structures. For an arbitrary set of oil concentrations and various formation materials, the response of the detectors in the logging tool has been considered as a criterion to assess the effect of modeling for the distribution of pores in the formation on simulation studies. The results show that defining a RR model for describing heterogeneities of a porous medium does not effectively improve the prediction of the responses of logging tools. Taking into account the computational cost of the particle transport in the complex geometries in the Monte Carlo method, the SP model can be satisfactory for gamma-gamma logging purposes.

Effects of Peroxide and Sulfur Curing Systems on Physical and Mechanical Properties of Nitrile Rubber Composites: A Comparative Study.

This study compares the effect of sulfur and dicumyl peroxide (DCP) vulcanizing systems on the physical and mechanical properties of rubber compounds based on acrylonitrile butadiene rubber (NBR). NBR compounds cured by different amounts of DCP and NBR vulcanizates filled with various concentrations of carbon black (CB) and a constant amount of sulfur or DCP were prepared. The vulcanizates were characterized by tensile testing, dynamic mechanical thermal analysis (DMTA), and cross-link density determination. The tensile strength and Young's modulus were found to increase with the rising amount of DCP and CB, while elongation at break decreased. The samples vulcanized by the sulfur system and filled with CB show a substantial increase in tensile strength from 13.1 to 21.2 MPa. Higher storage modulus and glass transition temperature were observed with the increase in the amount of peroxide and filler, and consequently, the increase in cross-link density, indicating rigidity increase and lower molecular mobility. The changes in the physical and mechanical properties of the NBR vulcanizates were in correlation with the changes in solvent uptake and cross-link density.

Estimation of Soil Density, Porosity, Water Holding Capacity, and Moisture content of Arpa River Based Soil

Soil physics plays a pivotal role in the present scenario. It is directly related to the economic growth of India. An attempt has been made in this paper to research as well as estimate some important physical properties of the Arpa River-based soil of Bilaspur, Chhattisgarh. For soil analysis, it is required to calculate different Chemical, Physical, and Electrical properties, and Geographical. The physical properties of soil are influenced by the size, arrangement, composition, and properties of soil particles. Six distinct soil samples are taken for the current study from different places in the Arpa River. Many physical properties of these six soil samples are examined, including bulk density, particle density, porosity, water holding capacity, soil moisture content, and so on. which can be determined by different standard methods and mathematical formulas. The bulk density in this study ranges from 1.1332 to 1.466 g/cm3. The range of particle density is 2.0449 to 2.5252 g/cm3. After the determination of Bulk density and particle density, the percentage of solid space and pore space (Porosity) was evaluated. Water holding capacity varies from 8% to 48%. The moisture content of six samples varies from 25.92% to 48.14%. Based on physico-chemical parameters it is easy to find the type and amount of fertilizers for particular crops.

Obtaining the empirical calibration dependence for express assessment of the quality of the performance of ground structures

In this study, the authors consider sand pads, namely the production process and quality control. The main problem of using the compacting factor as a criterion for assessing the quality of sand pads is the impossibility of calculating future deformations of foundations, as well as the duration of laboratory studies to determine it. Thus, the development of a technological solution for the use of express methods for controlling the compaction of soil structures, which are based on empirical data and can reduce the economic costs of construction, is an urgent task. The direct object of the study is the sand pad under the production facility. In the process of installing a sand pad, layer-by-layer control of the degree of compaction was carried out according to the compacting factor with the determination of the maximum density according to the method of GOST 22733-2016, and the modulus of soil deformation according to selected soil samples for compression tests. For each layer, the compaction coefficient was determined at 5 points, the deformation modulus at 3 points. Additionally, tests were carried out using a dynamic density meter. The main result of the study is the construction of a calibration dependence of the constrained modulus on the dynamic modulus of elasticity of the soil based on the results of statistical processing. Based on the test results, it was found that the experimental data are equally accurate, the resulting model is adequate. The difference between the experimental data and the calibration dependence does not exceed 18 %, which is a good convergence for empirical methods. The obtained experimental dependence allows, with a sufficient degree of accuracy, to quickly control the quality of the sand pad.

Experimental determination of intrinsic carrier density in 4H-SiC based on electron diffusion current in an npn bipolar junction transistor

The intrinsic carrier density of 4H-SiC at temperatures ranging from 294 to 595 K was derived by analyzing a collector current in an npn-type SiC bipolar junction transistor, the structure of which was designed based on a device simulation. The obtained intrinsic carrier density was in good agreement with the value calculated from the bandgap and effective densities of states taking multiple and non-parabolic SiC bands into account. The coincidence of the intrinsic carrier density obtained by these two different approaches indicates the usefulness of the proposed method and the validity of the evaluated value of intrinsic carrier density. The temperature dependence of the bandgap was also estimated from the deduced intrinsic carrier density and compared with an empirical formula. The derived bandgap agreed well with the empirical formula showing bandgap shrinkage at high temperatures. The errors in evaluating the intrinsic carrier density and the bandgap caused by the estimation of the hole density and electron mobility in the base layer are also discussed for the proposed method.

Reproductive risk factors for breast cancer and association with novel breast density measurements among Hispanic, Black, and White women.

There are differences in the distributions of breast cancer incidence and risk factors by race and ethnicity. Given the strong association between breast density and breast cancer, it is of interest describe racial and ethnic variation in the determinants of breast density. We characterized racial and ethnic variation in reproductive history and several measures of breast density for Hispanic (n = 286), non-Hispanic Black (n = 255), and non-Hispanic White (n = 1694) women imaged at a single hospital. We quantified associations between reproductive factors and percent volumetric density (PVD), dense volume (DV), non-dense volume (NDV), and a novel measure of pixel intensity variation (V) using multivariable-adjusted linear regression, and tested for statistical heterogeneity by race and ethnicity. Reproductive factors most strongly associated with breast density were age at menarche, parity, and oral contraceptive use. Variation by race and ethnicity was most evident for the associations between reproductive factors and NDV (minimum p-heterogeneity:0.008) and V (minimum p-heterogeneity:0.004) and least evident for PVD (minimum p-heterogeneity:0.042) and DV (minimum p-heterogeneity:0.041). Reproductive choices, particularly those related to childbearing and oral contraceptive use, may contribute to racial and ethnic variation in breast density.

Joint determination of Venus gravity and atmospheric density through EnVision radio science investigation

The ESA mission EnVision will address its main scientific questions through a detailed mapping of the surface and interior properties of Venus. A precise reconstruction of the spacecraft trajectory is a key requirement for the EnVision scientific investigations, including radio science. To precisely constrain the orbit evolution, refined models of the dynamical forces are included in the Precise Orbit Determination (POD) process. We developed a methodology based on a batch-sequential filter that enables a joint estimation of Venus gravity and atmospheric density. Our approach yields an accurate compensation of atmospheric mismodeling, simulated through semi-empirical predictions of the atmospheric density provided by general circulation models (GCM), e.g., Venus Climate Database (VCD). Numerical simulations of the EnVision radio science investigation were carried out by using a perturbative analysis of the dynamical forces, which accounts for atmospheric density errors ≥ 200%. By adjusting a set of atmospheric scale factors, our proposed strategy enables an estimation of the atmospheric density at the spacecraft altitudes with an accuracy of 25%. The improved dynamical model yields accuracies in the orbit reconstruction of 1–2 m, 30–40 m and 20–30 m in the radial, transverse and normal directions.

Estimating carbon storage using remote sensing in the Selo Resort forest area of Mount Merbabu National Park, Central Java, Indonesia

Abstract. Sulton MN, Putri NRA, Nugraheni RS, Afifah RN, Fadilah RN, Indrawan M, Kusumaningrum L, Sutarno, Sunarto, Sugiyarto, Pradhan P, Setyawan AD. 2023. Estimating carbon storage using remote sensing in the Selo Resort forest area of Mount Merbabu National Park, Central Java, Indonesia. Biodiversitas 24: 6264-6270. This study is of paramount importance for long-term climate change mitigation efforts, as it aims to estimate carbon storage and assess land cover density in Selo Resort forest area of Mount Merbabu National Park (MMbNP), Central Java, Indonesia, utilizing remote sensing techniques. Sentinel 2A satellite imagery, acquired on May 28, 2023, serves as the foundational dataset for this research. Employing ArcGIS 10.5, the satellite imagery was processed to derive the Normalized Difference Vegetation Index (NDVI), a critical parameter in this analysis. The NDVI values were subsequently employed to categorize land cover density, leading to the classification of land into five distinct classes: non-vegetation, shrubs, low density, medium density, and high density. This classification process enabled the determination of land cover density. The calculated values for each density class, namely low, medium, and high-density land cover, revealed substantial carbon storage potentials: 12,357.99 tons C, 92,871.04 tons C, and 73,542.06 tons C, respectively. Moreover, the computed areas for low, medium, and high-density cover were 202.59 ha, 364.93 ha, and 348.26 ha, respectively. This study underscores the need for ongoing monitoring to detect changes in land cover and to implement afforestation initiatives in areas with low-density vegetation. Such efforts are crucial for the preservation of land cover and the associated carbon storage benefits, thereby contributing to broader climate change mitigation strategies.

Extraction of device parameters from capacitance-voltage characteristics of p-GaN/AlGaN/GaN HEMT

This article presents unique methods for extracting essential device parameters of p-GaN/AlGaN/GaN HEMT from its gate capacitance-voltage characteristics. These parameters encompass p-GaN layer doping, AlGaN barrier layer thickness, threshold voltage, effective interface charge at AlGaN/GaN, and UID-GaN layer doping. Detailed step-by-step extraction techniques are elucidated, and their accuracy is rigorously validated against experimental and simulation data. The suggested methods are analytical and straightforward to comprehend. Furthermore, it enables the determination of trap density and its distribution at the AlGaN/GaN interface. These extraction processes play a crucial role in the comprehensive characterization of p-GaN/AlGaN/GaN HEMTs. The extracted device parameters can subsequently be used to improve device optimization, modelling, fabrication, and process control for normally-OFF p-GaN-gated HEMTs.

Identifying Rare Genetic Determinants for Improved Polygenic Risk Prediction of Bone Mineral Density and Fracture Risk.

Osteoporosis and fractures severely impact the elderly population. Polygenic risk scores for bone mineral density have demonstrated potential clinical utility. However, the value of rare genetic determinants in risk prediction has not been assessed. With whole-exome sequencing data from 436,824 UK Biobank participants, we assigned White British ancestry individuals into a training data set (n = 317,434) and a test data set (n = 74,825). In the training data set, we developed a common variant-based polygenic risk score for heel ultrasound speed of sound (SOS). Next, we performed burden testing to identify genes harboring rare determinants of bone mineral density, targeting influential rare variants with predicted high deleteriousness. We constructed a genetic risk score, called ggSOS, to incorporate influential rare variants in significant gene burden masks into the common variant-based polygenic risk score. We assessed the predictive performance of ggSOS in the White British test data set, as well as in populations of non-White British European (n = 18,885), African (n = 7165), East Asian (n = 2236), South Asian (n = 9829), and other admixed (n = 1481) ancestries. Twelve genes in pivotal regulatory pathways of bone homeostasis harbored influential rare variants associated with SOS (p < 5.5 × 10-7 ), including AHNAK, BMP5, CYP19A1, FAM20A, FBXW5, KDM5B, KREMEN1, LGR4, LRP5, SMAD6, SOST, and WNT1. Among 4013 (5.4%) individuals in the test data set carrying these variants, a one standard deviation decrease in ggSOS was associated with 1.35-fold (95% confidence interval [CI] 1.16-1.57) increased hazard of major osteoporotic fracture. However, compared with a common variant-based polygenic risk score (C-index = 0.641), ggSOS had only marginally improved prediction accuracy in identifying at-risk individuals (C-index = 0.644), with overlapping confidence intervals. Similarly, ggSOS did not demonstrate substantially improved predictive performance in non-European ancestry populations. In summary, modeling the effects of rare genetic determinants may assist polygenic prediction of fracture risk among carriers of influential rare variants. Nonetheless, improved clinical utility is not guaranteed for population-level risk screening. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Системний остеопороз та остеопенія у чоловіків із гіперурикемією

The article presents the results of own research on the study of the incidence of osteoporosis and osteopenia in men with different levels of uric acid and the influence of hyperuricemia on the mineral density of bone tissue. The aim of the study was to examine the structural and functional state of bone tissue (indicators of mineral density) in men with different levels of uric acid and to establish the incidence of osteoporosis and osteopenia in patients with hyperuricemia. Materials and methods of research. 140 men aged 50–80 years were examined. Determination of the level of uric acid in the serum was performed using the uricase-peroxidase method. Determination of bone mineral density was performed by DXA on the device «Prodigy». Results. It has been established that the incidence of osteoporosis and osteopenia in men with hyperuricemia is lower compared to men with normouricemia. When dividing by age groups 50–59 years, 60–69 years, 70–79 years in men with hyperuricemia, osteoporosis was detected only in the age group 70–79 years and its incidence was 14% at the level of the lumbar spine (L1–L4) and 14% at the level of the femoral neck (Neack Mean). According to the quarterly distribution according to the level of uric acid, men with the highest level of uric acid had the highest indicators of bone mineral density. Conclusions. Patients with a high level of uric acid have high levels of bone mineral density, so they are less likely to develop diseases such as osteoporosis and osteopenia, which indicates the protective role of uric acid for bone tissue and may be of practical importance when deciding on the issue of drug correction of hyperuricemia.