Central Cube Research Articles

Development and validation of CNN-MLP models for predicting anti-VEGF therapy outcomes in diabetic macular edema

Diabetic macular edema (DME) is a common complication of diabetes that can lead to vision loss, and anti-vascular endothelial growth factor (anti-VEGF) therapy is the standard of care for DME, but the treatment outcomes vary widely among patients. This study collected optical coherence tomography (OCT) images and clinical data from DME patients who received anti-VEGF treatment to develop and validate deep learning (DL) models for predicting the anti-VEGF outcomes in DME patients based on convolutional neural network (CNN) and multilayer perceptron (MLP) combined architecture by using multimodal data. An Xception-MLP architecture was utilized to predict best-corrected visual acuity (BCVA), central subfield thickness (CST), cube volume (CV), and cube average thickness (CAT). Mean absolute error (MAE), mean squared error (MSE) and mean squared logarithmic error (MSLE) were employed to evaluate the model performance. In this study, both the training set and the validation set exhibited a consistent decreasing trend in MAE, MSE, and MSLE. No statistical difference was found between the actual and predicted values in all clinical indicators. This study demonstrated that the improved CNN-MLP regression models using multimodal data can accurately predict outcomes in BCVA, CST, CV, and CAT after anti-VEGF therapy in DME patients, which is valuable for ophthalmic clinical decisions and reduces the economic burden on patients.

Factors Affecting Compliance and Visual Outcomes in Patients Receiving Intravitreal Bevacizumab Injections.

Background Vascular endothelial growth factor (VEGF) is a powerful mitogen for endothelial cells that promotes migration, proliferation, and tube formation necessary for the angiogenic development of new blood vessels. When VEGF increases significantly, it causes pathological angiogenesis and increased vascular permeability in eye conditions such as diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinal vein occlusion (RVO). These disorders have become important global sources of morbidity and have a substantial financial impact not only on the medical community but also on the patients. Therefore, this study aims to determine the success rates of intravitreal bevacizumab therapy and the visual outcomes which may be increased by determining the factors affecting patient compliance and raising awareness about DR, neovascular AMD, and RVOamong patients and studying the factors responsible for non-compliance to treatment. Methodology This experimental pre-post study was conducted in the ophthalmology department at a tertiary care hospital and research center in western Maharashtra from September 2022 to June 2024. A total of 150 eyes of 150 patients who were diagnosed cases of DR, neovascular AMD, and non-ischemic RVOwere included in the study.Written informed consent was obtained from each patient. Data were entered in Microsoft Excel (Microsoft Corp., Redmond, WA, USA) and statistical analysis was done using SPSS 27.0 software (IBM Corp., Armonk, NY, USA). The chi-square test was employed to check the association between categorical variables. Pearson's correlation test was used, and p-values <0.05 were considered significant. Results The compliance rate in our study was 79.3% (113 individuals). In our study, 58% (87 individuals) were male while 42% (63 individuals) were females. Most patients were from urban areas 74.7% (112 individuals). Among the study participants, DR patients constituted 48.6% (73 individuals), while neovascular AMD and RVO were seen in 32% (48 individuals) and 19.4% (29 individuals), with 62% (93 individuals) being diabetic and 64.7% (97 individuals) being hypertensive. In our study, 92% (138 individuals) were willing to take treatment, with 88.7% (133 individuals) worried about their visual outcomes and 66% (99 individuals) afraid of getting injected. Appointments posed a financial burden to 30.7% (46 individuals) of patients, with 55.3% (83 individuals) having transportation issues. Overall, 18.7% (28 individuals) of patients had missed appointments between 14 and 90 days while 30.7% (46 individuals) had missed their appointments by 90 and 365 days. Younger patients with a shorter duration of diabetes had higher compliance rates. Post-injection, there was an overall significant improvement in vision as well as a reduction in the central subfield macular thickness, volume cube, and thickness average cube. Conclusions In the present study, four-fifths of the patients were compliant with treatment, and visual improvement was significant. In addition, there was a significant reduction in the macular thickness after the treatment. One of the factors for non-compliance included in our study was the need for follow-up. Younger patients and those with a shorter duration of diabetes had significantly higher compliance. We recommend further studies should be conducted to compare the effectiveness with the control group in randomized control trials.

New findings on retinal microvascular changes in patients with primary COVID-19 infection: a longitudinal study.

To investigate the longitudinal alterations of retinal microvasculature in patients with primary coronavirus disease 2019 (COVID-19) infection. A cohort of participants, who had never been infected with COVID-19, was recruited between December 2022 and May 2023 at Peking Union Medical College Hospital in Beijing, China. Participants underwent comprehensive ophthalmologic examinations and fundus imaging, which included color fundus photography, autofluorescence photography, swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA). If participants were infected with COVID-19 during the study, follow-ups with consistent imaging modality were conducted within one week and two months after recovery from the infection. 31 patients (61 eyes), with a mean age of 31.0 ± 7.2 years old, were eligible for this study. All participants contracted mild COVID-19 infection within one month of baseline data collection. The average period was 10.9 ± 2.0 days post-infection for the first follow-up and 61.0 ± 3.5 days for the second follow-up. No clinical retinal microvasculopathy features were observed during the follow-ups. However, SS-OCTA analysis showed a significant increase in macular vessel density (MVD) from 60.76 ± 2.88% at baseline to 61.59 ± 3.72%(p=0.015) at the first follow-up, which subsequently returned to the baseline level of 60.23 ± 3.33% (p=0.162) at the two-month follow-up. The foveal avascular zone (FAZ) remained stable during the follow-ups with areas of 0.339 ± 0.097mm2, 0.342 ± 0.093mm2, and 0.344 ± 0.098mm2 at the baseline, first follow-up (p=0.09) and second follow-up (p=0.052), respectively. Central macular thickness, cube volume and ganglion cell-inner plexiform layer showed a transient decrease at the first follow-up(p<0.001, p=0.039, p=0.002, respectively), and increased to baseline level at the two-month follow-up(p=0.401, p=0.368, p=0.438, respectively). Mild COVID-19 infection may temporarily and reversibly impact retinal microvasculature, characterized by a transient increase in retinal blood flow during the early recovery phase, which returns to the pre-infection level two months post-infection.

Mechanical Properties of Lattice Structures with a Central Cube: Experiments and Simulations.

In this study, a new structure is proposed based on the body-centered cubic (BCC) lattice structure by adding a cubic truss in the center of the BCC structure and denoting it TLC (truss-lattice-cube). The different dimensions of the central cube can notably affect the mechanical properties of the lattice structure. With a fixed length (15 mm) of a unit cell, the optimal size for the central cube is determined to be 5 mm. Quasi-static compressive tests are performed on specimens made of polylactic acid (PLA) using additive manufacturing technology. The deformation characteristics of the new structure are analyzed in detail by experiments and numerical simulations. Compared to the BCC structure, the mechanical properties of the TLC structure were significantly improved. The initial flow stress of the TLC increased by 122% at a strain of 0.1; the specific strength enhanced by 293% at a strain of 0.5; and the specific energy absorption improved by 312% at a strain of 0.6. Printing defects in the lattice structure may remarkably damage its mechanical properties. In this work, incorporation of microcracks into the finite element model allows the simulation to capture the influence of printing defects and significantly improve the predictive accuracy of the simulation.

Interocular Symmetry and Intermachine Reproducibility of Optic Disc and Macular Parameters Measured by Two Different Models of Optical Coherence Tomography.

To compare the interocular symmetry and investigate the intermachine reproducibility of optic disc and macular data measured by spectral-domain high-definition optical coherence tomography (HD-OCT) Cirrus HD-OCT 4000 and HD-OCT 5000 from healthy subjects. Forty-three volunteers were examined with both HD-OCT 4000 and HD-OCT 5000 at the same visit. Optic nerve head (ONH) and macular data were acquired using ONH Cube 200×200 scans and macular volume cube 512×128 scans, respectively. The average age of the participants was 33 ± 8.6 years. Interocular OCT parameters of ONH and macula showed a high correlation between the right and left eyes regardless of HD-OCT models, displaying a low coefficient of variation (CV). However, the average retinal nerve fiber layer (RNFL) was thicker (96.67±11.19µm vs 95.3±10.89µm, p<0.01), and the average central subfield thickness (261.51±17.45µm vs 262.51±17.39 µm, p<0.01) and cube average thickness (283.91± 13.59µm vs 286.55±13.09µm, p<0.05) were thinner when measured by Cirrus 4000 compared to 5000. Intermachine reproducibility and reliability of RNFL and macular parameters exhibited a high intraclass correlation coefficient (ICC) (0.985) and low CV (2.4%). Ganglion cell-inner plexiform layer (GCIPL) measured by two OCT models showed similar values with an average thickness of 85 µm and had high intermachine reproducibility with high ICC (0.993) and low CV (1.2%). High interocular symmetry was observed across both HD-OCT models. Intermachine reproducibility for RNFL and all macular parameters was also high. GCIPL showed minimal intermachine differences with high reproducibility and reliability. Thus, the results imply that GCIPL values measured by two Cirrus OCT models may be used interchangeably.

Enhancing nitrogen removal from wastewater in a low C/N ratio using an air-lift bio-electrochemical reactor (ALBER)

This study focuses on the development of an air-lift bio-electrochemical reactor (ALBER) with a continuous feeding regime. The objective is to enhance nitrogen removal from synthetic wastewater with a low carbon-to-nitrogen (C/N) ratio. The chemical oxygen demand (COD) and total nitrogen (TN) of the influent wastewater were 500 and 200 mg/L, respectively. The effect of four independent variables, i.e., temperature, hydraulic retention time (HRT), N−NH4+/TN ratio and current density in the range of 16–32 °C, 6–12 h, 25–75%, and 2–10 A/m2, respectively, at three levels on the bio–electrochemical reactor performance were investigated during the bio–electrochemical reactor operation. The Face Center Cube (FCC) of response surface methodology (RSM) was used for design of experiments and model of obtained data. The ALBER achieved the maximum TN removal of 73% (146 mg/l) using external voltage and zeolite/plastic medium at temperature of 16 °C, HRT of 6 h, current density of 2 A/m2 and N−NH4+/TN ratio of 75%. The results indicated that shortening the HRT from 12 to 6 h, reducing the temperature from 32 °C to 24 °C, increasing the current density from 2 to 6 A/m2 and the reduction of nitrate concentration caused an increase in the TN removal. The results indicated that the performance of air-lift bio-electrochemical for nitrogen removal could be attributed to autotrophic denitrification (AD) and simultaneous nitrification/denitrification (SND). The research findings suggest that the ALBER should be further studied for potential use in treating industrial wastewater at low temperatures.

Decreased Central Macular Choriocapillaris Perfusion Correlates With Increased Low Luminance Visual Acuity Deficits

Correlations between low luminance visual acuity deficits (LLVADs) and central choriocapillaris perfusion deficits were investigated to help explain how increases in LLVAD scores at baseline predict annual growth rates of geographic atrophy (GA). Prospective cross-sectional study. Photopic luminance best-corrected visual acuity (PL-BCVA) and low luminance BCVA (LL-BCVA) were measured using the Early Treatment Diabetic Retinopathy Study chart. LL-BCVA was measured using a 2.0-log unit neutral density filter. LLVADs were calculated as the difference between PL-BCVA and LL-BCVA. Within a fovea-centered 1-mm circle, the percentage of choriocapillaris flow deficits (CC FD%), drusen volume, optical attenuation coefficient (OAC) elevation volume, and outer retinal layer (ORL) thickness were assessed. In all 90 eyes (30 normal eyes; 31 drusen-only eyes; 29 non-foveal GA eyes), significant correlations were found between the central CC FD% and PL-BCVA (r=-0.393, P < .001), LL-BCVA (r=-0.534, P < .001), and the LLVAD (r=0.439, P < .001). Central cube root (cubrt) drusen volume, cubrt OAC elevation volume, and ORL thickness were correlated with PL-BCVA, LL-BCVA, and LLVADs (all P < .05). Stepwise regression models showed that central cubrt OAC elevation volume and ORL thickness were associated with PL-BCVA (R2=0.24, P < .05); central CC FD%, cubrt OAC elevation volume, and ORL thickness were associated with LL-BCVA (R2=0.44, P < .01); and central CC FD% and ORL thickness were associated with LLVAD (R2=0.24, P < .01). The significant correlations between central CC FD% and LLVAD support the hypothesis that the ability of LLVAD to predict the growth of GA is mediated through a decrease in macular choriocapillaris perfusion.

Silver Recovery from End-of-Life Photovoltaic Panels Based on Microbial Fuel Cell Technology

The solar energy sector has grown rapidly in the past decades, addressing the issues of energy security and climate change. Many photovoltaic (PV) panels that were installed during this technological revolution, have accumulated as waste and even more are nearing their End-of-Life (EoL). Based on circular economy, a new hydrometallurgical process has been proposed for the management of the EoL PVs. This results in a chemical extract containing 0.7% w/w Ag, along with various other metals. This study investigates the MFC technology as an alternative method for valuable metal recovery from the chemical extract of PV panels. Moreover, metal recovery from the chemical extract is compared with the individual recoveries obtained using corresponding synthetic solutions. The results indicated that silver was completely recovered from the synthetic and the real chemical extract, with a rate of ~ 82 and ~ 32 μmol/h, respectively. The difference is attributed to the simultaneous reduction of other heavy metals in amorphous compounds, hindering the silver reduction kinetics and leading to a gradual electrode passivation. Nevertheless, silver can be 100% retrieved from the chemical extract, with a purity of 68–96% w/w (average 86% w/w), in crystal (face center cube) structure, containing minor metal impurities.Graphical

Fundus autofluorescence in the evaluation of diabetic macular edema treatment response.

Fundus autofluorescence (FAF) has shown sensitivity in the detection of macular edema. To evaluate indices formed with FAF and retinal anatomical-functional variables in patients with diabetic macular edema (DME) treated with ziv-aflibercept (ziv-AFL). Twenty-nine eyes of 15 DME patients who received ziv-AFL intravitreal injections were included in the study. Best-corrected visual acuity (BCVA), contrast sensitivity (CS), optical coherence tomography (OCT) and FAF were evaluated before treatment and at one and two months. OCT variables were central subfield thickness (CST), macular volume (MV) and macular cube average thickness (MCAT). FAF/BCVA, FAF/CS, FAF/CST, FAF/MV and AF/MCAT indices baseline values were obtained. Analysis was performed with Spearman's rank correlation coefficient and linear regression analysis. There was a significant correlation between baseline FAF/BCVA index and BCVA at second month (rs = - 0.78, p = 0.000), between baseline FAF/CS index and BCVA at second month (rs = -0.68, p = 0.0009) and between baseline FAF/CS index and MV at first month of follow-up (rs = 0.64, p = 0.002). In DME, composite indices with baseline FAF predict variables such as BCVA in the follow-up of patients receiving ziv-AFL.

Macular Parameters Change during Silicon Oil Tamponade for Retinal Detachment Surgery.

Background and Objectives: To evaluate possible changes in macular thickness parameters during and after silicon oil tamponade and in pars plana rhegmatogenous retinal detachment surgery. Materials and Methods: Our retrospective study included 34 consecutive patients who underwent 23-gauge retinal detachment surgery with silicon oil tamponade. Central macular thickness (CMT), central macular volume cube (CMV) and average macular thickness cube (AVG) were measured by optical coherence tomography (OCT) before rhegmatogenous retinal detachment surgery with silicon oil tamponade during tamponade (seven days, one month and three months after surgery), and one month after silicon oil removal. Results: In our sample, macular parameters CMT, CMV and AVG in patients who underwent retinal detachment surgery were statistically reduced during silicon oil tamponade (p < 0.05). After silicon oil removal, all parameters recovered, reaching numeric values which were not statistically significant compared to preoperative values. The average span of silicon oil tamponade was 162 +/- 23 days. Conclusions: Silicon oil tamponade during 23-gauge rhegmatogenous retinal detachment surgery leads to a transitory reduction of central macular thickness, central macular volume cube and average macular thickness cube in eyes that underwent retinal surgery. After silicon oil removal, macular parameters returned to preoperative values in most of the patients.

Some remarks on dimension-free estimates for the discrete Hardy—Littlewood maximal functions

Dependencies of the optimal constants in strong and weak type bounds will be studied between maximal functions corresponding to the Hardy—Littlewood averaging operators over convex symmetric bodies acting on ℝd and ℤd. Firstly we show, in the full range of p ∈ [1, ∞], that these optimal constants in Lp (ℝd) are always not larger than their discrete analogues in ℓp(ℤd); and we also show that the equality holds for the cubes in the case of p = 1. This in particular implies that the best constant in the weak type (1, 1) inequality for the discrete Hardy—Littlewood maximal function associated with centered cubes in ℤd grows to infinity as d → ∞, and if d = 1 it is equal to the largest root of the quadratic equation 12C2 − 22C + 5 = 0. Secondly we prove dimension-free estimates for the ℓp(ℤd) norms, p ∈ (1, ∞], of the discrete Hardy—Littlewood maximal operators with the restricted range of scales t ≥ Cqd corresponding to q-balls, q ∈ [2, ∞). Finally, we extend the latter result on ℓ2(ℤd) for the maximal operators restricted to dyadic scales 2n ≥ Cqd1/q.

Comparison of Supercritical Fluid Extraction and Ultrasound-Assisted Extraction of Corchorus Olitorius L. and Evaluation of Their Antioxidant Properties and Identification of Compounds Using LC-ESI-MS

Corchorus olitorius L. is a medicinal herb with anti-inflammatory, laxative, and tonic properties, which is effective on the treatment of cancer and tumors. In this study, the extraction efficiency of supercritical fluid extraction (SFE) and ultrasound-assisted extraction (UAE) of C. olitorius as well as their antioxidant activities were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. For this purpose, central composite block cube star and central composite design were employed to determine the optimal conditions. Thereafter, the qualification analysis of the effective ingredients of C. olitorius was done by LC-ESI-MS in negative mode. The results of LC-MS showed that C. olitorius includes phenolic and flavonoid compounds such as caffeic acid, p-coumaric acid, trans-ferulic acid, quercetin, naringenin, cirsiliol, cirsilineol, quercetrin, and naringin. Moreover, the SFE efficiency of extraction and IC50 value was obtained 4.25% and 1208.99 µg/mL, respectively. Also, the UAE efficiency of extraction and IC50 of antioxidant activity was obtained as 15.29% and 994.284 µg/mL, respectively. These results confirmed that the efficiencies of extraction and antioxidant activity of UAE were higher than that of SFE; however, the SFE is an environmentally friendly method and consumed less organic solvent.

Aqueous angiopoietin-like levels correlate with optical coherence tomography angiography metrics in diabetic macular edema.

To quantitatively detect aqueous levels of angiopoietin-like (ANGPTL)3, ANGPTL4, and ANGPTL6 and investigate their correlation with optical coherence tomography angiography (OCTA) findings in patients with diabetic macular edema (DME). This cross-sectional study included 23 patients (27 eyes) with type 2 diabetes and 16 control subjects (20 eyes). All patients underwent OCTA imaging and ultra-wide field fundus photography. Diabetic patients were categorized into two groups according to the presence or absence of diabetic retinopathy (DME group, 14 patients, 16 eyes); and non-diabetic retinopathy (NDR) group, 9 patients, 11 eyes, respectively. Aqueous levels of ANGPTL3, ANGPTL4, and ANGPTL6 were assessed using suspension array technology, and foveal-centered 3×3 mm2 OCTA scans were automatically graded to determine the central, inner, and full vessel density (CVD, IVD, FVD); central, inner, and full perfusion density (CPD, IPD, FPD), foveal avascular zone (FAZ) area, FAZ perimeter, and FAZ circularity index (FAZ-CI) on superficial capillary plexuses. Additionally, central subfield thickness (CST), cube volume (CV), and cube average thickness (CAT) were measured in a model of macular cube 512×128. Aqueous ANGPTL3 levels were not significantly different among the three groups (P>0.05). ANGPTL4 levels were significantly higher in the DME group than the control and NDR groups (P<0.0001 and P<0.001), while ANGPTL6 levels were significantly higher in the DME group than the control group (P<0.05). In the whole cohort, the aqueous ANGPTL3 levels correlated negatively with the IVD, FVD, IPD, and FPD, and positively with the CV and CAT. The aqueous ANGPTL4 levels correlated negatively with the CVD, IVD, FVD, CPD, IPD, and FPD, and positively with the FAZ perimeter, CST, CV, and CAT. The aqueous ANGPTL6 levels correlated negatively with the IVD, FVD, IPD, FPD, FAZ-CI and positively with CST, CV, CAT. ANGPTL4 and ANGPTL6 may be associated with vascular leakage in DME and may represent good targets for DME therapy. In addition, OCTA metrics may be useful for evaluating macular ischemia in DME.

Effects of cigarette smoking on sensorineural hearing impairment and age related macular degeneration.

INTRODUCTIONCigarette smoking has been causally associated with various diseases, and among the numerous harmful effects of smoking is included its impact on the senses of vision and hearing. The purpose of this study is to evaluate the impact of cigarette smoking on the visual and auditory functions.METHODSIn this analytic study, hearing and smoking status of 40 patients with agerelated macular degeneration (AMD) were analyzed with 40 age-matched control subjects without AMD. In all subjects (n=80), retinal status was investigated by optical coherence tomography (OCT), with analyses of thickness central subfield (TCS) and thickness average cube (TAC) of the macula. All participants were examined with pure tone audiometry. Audiometric trials comprised pure tone bone and air conduction. The smoking history of all the subjects was recorded in detail.RESULTSA significant correlation was found between smoking status and visual (p<0.001) and hearing impairment (p<0.05). Cigarette smoking was found to be highly correlated with sensorineural hearing impairment and exudative macular degeneration.CONCLUSIONSCigarette smoking damage anti-oxidative systems and tissue metabolism. We have underlined a clear correlation between the risk of sensorineural hearing impairment, exudative macular degeneration and cigarette smoking. Our findings may result in future screening of smokers to identify any hearing and vision impairment and for improving smoking cessation interventions.

Elevated Serum Immunoglobulin E Levels are Associated with the Severity of Newly Diagnosed, Acute Vogt–Koyanagi–Harada Disease

ABSTRACT Objective To investigate the correlation between serum immunoglobulin E (IgE) levels and severity of Vogt–Koyanagi–Harada (VKH) disease. Methods The medical records of patients with VKH disease between 2015 and 2020 were reviewed. Serum immunoglobulins (IgA, IgE, IgG, and IgM), tumor necrosis factor α (TNFα) and C-reactive protein (CRP) were measured. Patients were divided into IgE-positive (IgE ≥ 100 IU/mL) and IgE-negative (IgE < 100 IU/mL) groups. The best-corrected visual acuity (BCVA) and macular morphologic characteristics including foveal thickness (FT), serous retinal detachment (SRD), sensory retinal thickness (SRT), central foveal thickness (CFT), cube volume (V), and cube average thickness (AT) were determined in patients in both groups. Results Of 128 patients included in the study, 35 (27.34%) patients were IgE-positive, BCVA (logMAR) was worse in the IgE-positive group. The mean CRP (P= .012) and TNFα (P≤ 0.001) levels were greater in the IgE-positive group than in the IgE-negative group. Regarding macular morphologic characteristics, FT (P= .010), SDR (P= .004), CFT (P= .008), V (P= .013), and AT (P= .006) were significantly greater in the IgE-positive group than in the IgE-negative group. Conclusions Elevated serum IgE levels were associated with more severe macular changes in patients with VKH disease. These findings suggest that IgE may be involved in the progression of VKH disease.

Increase in linear attenuation coefficient by changing crystal structure of materials for radiation shielding and biomedical devices safety

Linear attenuation coefficient of materials plays an important role in shielding and protection from radiation. It has been observed that higher the density of a material, higher is its linear attenuation coefficient. Thus, to make a material more suitable for shielding from hazards of radiation, one should increase its linear attenuation coefficient through increase in density of the material. The present work reports that density and linear attenuation coefficient of a material can be increased if its crystalline structure is changed from simple cubical structure to body centered cube (BCC) and faced centered cube (FCC). Results show that by changing the crystal structure of a material, its atomic packing factor also increases which is responsible for increase in density and linear attenuation coefficient. Results also show that linear attenuation coefficient increased by 30% when a crystal structure is changed from simple cubical to BCC. An increase of 41% is found when simple cubical structure transforms to FCC structure. This enhances the ability of the material to be used for radiation shielding and cancer prevention.

Studies on calculation models of ASTRA critical facility benchmark using OpenMC

In this paper we report validation studies of the Monte Carlo code OpenMC by the ASTRA critical facility benchmark. A high-fidelity reactor model is built using the regular lattice coated fuel particle and the body centered cube pebble spheres representations. Two nuclear data libraries, ENDFB-7.0 and ENDFB-7.1 are considered to investigate the validity of nuclear cross section libraries. In addition, three homogenization models namely the core-hom model, the ref-hom model and the CR-hom model are built to provide references for analyzing the spatial approximations employed in deterministic codes. The core-hom model equivalents the octahedral core by a cylindrical zone, the ref-hom model homogenizes the side reflector into a cylindrical region, and the CR-hom model approximates the tube-cluster-shaped control rods (CR) into a concentric annulus. Results demonstrate that ENDFB-7.1 library outperforms ENDFB-7.0 by predicting criticality more accurately. The difference between the two libraries is 1224 pcm for the criticality calculation at the experimental pebble bed height (268.9 cm). With ENDFB-7.1 the high-fidelity model well-predicts the experimental data by 620 pcm error in keff and less than 6.5% difference in CR worth. The homogenization of the reflector brings about a pronounced error of 1143 pcm. In contrast, the core-hom model causes a comparably minor discrepancy of 241 pcm to the keff, while its influence on the CR worth appears most significant for CRs located close to the core zone. The CR-hom model yields a −2.1% maximum accuracy loss in CR worth from the high-fidelity model. After all, both the high-fidelity model and the core-hom model succeed in capturing the CR interference effect and in predicting the trend of CR differential worth. This work is not only meaningful for demonstrating the validity of OpenMC, but also useful to investigate the numerical accuracy of codes used in emerging work related to PBHTGR.

Numerical analysis of thermal storage characteristics of stacked lunar regolith spheres

As a kind of in-situ resource utilization, the regolith thermal energy storage is a promising way to solve the energy crisis of manmade moon base during the long lunar nighttime of 350 h. In this paper, a lunar regolith thermal storage system is designed and two different stacking methods of lunar regolith spheres are proposed, the thermal storage characteristics of stacked lunar regolith spheres is investigated numerically. The porous media model is applied to simulate the transient temperature and helium flow fields inside regolith thermal reservoir. The influences of regolith sphere diameter and pump pressure on the performance of a lunar regolith thermal reservoir are analyzed. The results show that there exist optimization regolith sphere diameter and pump pressure to the performance of regolith thermal energy reservoir. The optimization circular pump pressure for helium flow is dependent on the stacking method. When the pump pressure increases over 450 Pa, the face centered cubes (FCC) stacking method shows a maximum advantage of 305.6 kWh heat storage amount over the simple cubes (SC) stacking method. The designed lunar regolith thermal reservoir has the thermal storage density of 0.25 kWh kg−1 for one lunar day.

OFAT versus DOE as two optimization protocols for the chromatographic analysis of some OTC pharmaceuticals carrying negative cardiovascular effects and administered by pregnant and breast-feeding females: Application to dose dependent effect

AbstractA simple HPLC technique has been utilized for rapid and sensitive quantitative analysis of two mixtures of drugs that are used during pregnancy and lactation. Drugs of the first mixture are used to manage gastrointestinal tract illness that are common during early stages of pregnancy, while pharmaceutical agents of the second mixture are administered over the counter as galactagogues or to overcome postpartum depression. Mixture I includes famotidine (FMT), ranitidine (RNT), nizatidine (NZT), and pantoprazole (PNT), which were separated on a C18 column using a mobile phase composed of methanol: 0.02 M sodium dihydrogen phosphate (60:40, v/v) of pH 6.9, adopting UV detection at 240 nm at a flow rate of 1 mL/min. Mixture II on the other hand, consists of domperidone (DOM), metoclopramide (MET), and sulpiride (SUL). These drugs were eluted using the same column and flow rate as those in mixture I, using a mobile phase consisting of acetonitrile: 0.075 M sodium dihydrogen phosphate (30:70, v/v) of pH 6 adopting a detection wavelength 270 nm. Two optimization protocols were utilized to optimize the chromatographic separation conditions, namely one factor at a time (OFAT) and design of experiments (DOE) where face centered cube response surface experimental design was chosen for this investigation. Comparison of the results obtained from both protocols reveals the accordance between them.Full validation procedure under guidance of United States Pharmacopoeia (USP) was applied to the proposed methods which enabled their application to separate the drugs of both mixtures in spiked rat whole blood samples and in vivo analysis of rat heart blood.

A modular, easy-to-use microcapillary electrophoresis system with laser-induced fluorescence for quantitative compositional analysis of trace organic molecules.

Microcapillary electrophoresis (μCE) enables high-resolution separations in miniaturized, automated microfluidic devices. Pairing this powerful separation technique with laser-induced fluorescence (LIF) enables a highly sensitive, quantitative, and compositional analysis of organic molecule monomers and short polymers, which are essential, ubiquitous components of life on Earth. Improving methods for their detection has applications to multiple scientific fields, particularly those related to medicine, industry, and space science. Here, a modular benchtop system using μCE with LIF detection was constructed and tested by analyzing standard amino acid samples of valine, serine, alanine, glycine, glutamic acid, and aspartic acid in multiple borate buffered solutions of increasing concentrations from 10 mM to 50 mM, all pH 9.5. The 35 mM borate buffer solution generated the highest resolution before Joule heating dominated. The limits of detection of alanine and glycine using 35 mM borate buffer were found to be 2.12 nM and 2.91 nM, respectively, comparable to other state-of-the-art μCE-LIF instruments. This benchtop system is amenable to a variety of detectors, including a photomultiplier tube, a silicon photomultiplier, or a spectrometer, and currently employs a spectrometer for facile multi-wavelength detection. Furthermore, the microdevice is easily exchanged to fit the desired application of the system, and optical components within the central filter cube can be easily replaced to target alternative fluorescent dyes. This work represents a significant step forward for the analysis of small organic molecules and biopolymers using μCE-LIF systems.