Original Structure Research Articles

Elemental doping tailoring photocatalytic hydrogen evolution of InP/ZnSeS/ZnS quantum dots

Photocatalytic water splitting for hydrogen production has garnered considerable attention as an effective method to alleviate energy shortages. In comparison to cadmium-based quantum dots (QDs) photocatalysts, InP QDs possess a smaller bandgap, larger exciton radius, broader absorption range, and are environmentally friendly. Although InP/ZnS core/shell QDs exhibit immense potential in photocatalysis, they suffer from rapid electron-hole recombination owing to interface defects and lattice mismatch. To address these issues, this study introduces an intermediate ZnSeS shell to reduce defects and tailor QD redox properties through transition metals (manganese and copper) doping. The characterization of QDs were performed from various perspectives, including morphology, element distribution, band structure, and charge transport efficiency. Notably, the photoelectrochemical properties of doped QDs were superior to those of the undoped QDs, while Mn-doped QDs showed inferior catalytic performance compared to the undoped ones. The mechanism of different photoelectrochemical and photocatalytic performances has been studied more intensely. The Mn-doped QDs undergo a process where Mn4+ is converted to Mn2+, consuming electrons in competition with the photocatalytic hydrogen evolution process. Conversely InP/ZnSeS:Cu/ZnS QDs introduced an additional energy level into the original band structure, capturing some holes and slowing down the electron-hole recombination, thereby providing positive feedback for photocatalytic hydrogen production. Profiting from both the synergies of energy level structure and doping metal state, effective electron-hole separation, and rapid electron transfer to the surface of Cu-doped QDs accomplish the efficient hydrogen generation. The present study offers more possibilities for exploiting the required photocatalytic performance of QD catalysts via elemental doping.

Origins of fine structure in DNA melting curves.

With the help of the one-dimensional random Potts-like model, we study the origins of fine structures observed on differential melting profiles of double-stranded DNA. We theoretically assess the effects of sequence arrangement on DNA melting curves through the comparison of results for random, correlated, and block sequences. Our results re-confirm the smearing out of the fine structure with the increase in chain length for all types of sequence arrangements and suggest that the fine structure is a finite-size effect. We have found that the fine structures on melting curves of chains comprised of blocks with correlations in sequence are more persistent, probably because of increased sequence disorder the blocks introduce. Many natural DNAs show a well-expressed fine structure of melting profiles. Our results for block sequences may suggest the existence of such sequence motifs in natural DNA sequences.

X-ray Characterizations of Exfoliated MoS2 Produced by Microwave-Assisted Liquid-Phase Exfoliation

An X-ray analysis of exfoliated MoS2, produced by means of microwave-assisted liquid-phase exfoliation (LPE) from bulk powder in 1-methyl-2-pyrrolidone (NMP) or acetonitrile (ACN) + 1-methyl-2-pyrrolidone (NMP) solvents, has revealed distinct structural differences between the bulk powder and the microwave-exfoliated samples. Specifically, we performed X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements to identify the elements of our exfoliated sample deposited on a Si substrate by drop-casting, as well as their chemical state and its structural crystalline phase. In the exfoliated sample, the peaks pattern only partially resemble the theoretical Miller indices for MoS2. In contrast, the bulk powder’s spectrum shows the characteristic peaks of the 2H polytype of MoS2, but with some broadening. Notable is the retention of partial crystallinity in the post-exfoliation phases, specifically in the normal-to-plane orientation, thus demonstrating the effectiveness of microwave-assisted techniques in producing 2D MoS2 and attaining desirable properties for the material. XPS measurements confirm the success of the exfoliation procedure and that the exfoliated sample retains its original structure. The exfoliation process has been optimized to maintain the structural integrity of MoS2 while enhancing its surface area and electrochemical performance, thereby making it a promising material for advanced electronic and optoelectronic applications ranging from energy storage to sensing devices under ambient conditions.

Adaptation and validation of the evidence-based practice profile (EBP2) questionnaire in a Norwegian primary healthcare setting

BackgroundAccess to valid and reliable instruments is essential in the field of implementation science, where the measurement of factors associated with healthcare professionals’ uptake of EBP is central. The Norwegian version of the Evidence-based practice profile questionnaire (EBP2-N) measures EBP constructs, such as EBP knowledge, confidence, attitudes, and behavior. Despite its potential utility, the EBP2-N requires further validation before being used in a cross-sectional survey targeting different healthcare professionals in Norwegian primary healthcare. This study assessed the content validity, construct validity, and internal consistency of the EBP2-N among Norwegian primary healthcare professionals.MethodsTo evaluate the content validity of the EBP2-N, we conducted qualitative individual interviews with eight healthcare professionals in primary healthcare from different disciplines. Qualitative data was analyzed using the “text summary” model, followed by panel group discussions, minor linguistic changes, and a pilot test of the revised version. To evaluate construct validity (structural validity) and internal consistency, we used data from a web-based cross-sectional survey among nurses, assistant nurses, physical therapists, occupational therapists, medical doctors, and other professionals (n = 313). Structural validity was tested using a confirmatory factor analysis (CFA) on the original five-factor structure, and Cronbach’s alpha was calculated to assess internal consistency.ResultsThe qualitative interviews with primary healthcare professionals indicated that the content of the EBP2-N was perceived to reflect the constructs intended to be measured by the instrument. However, interviews revealed concerns regarding the formulation of some items, leading to minor linguistic revisions. In addition, several participants expressed that some of the most specific research terms in the terminology domain felt less relevant to them in clinical practice. CFA results exposed partial alignment with the original five-factor model, with the following model fit indices: CFI = 0.749, RMSEA = 0.074, and SRMR = 0.075. Cronbach’s alphas ranged between 0.82 and 0.95 for all domains except for the Sympathy domain (0.69), indicating good internal consistency in four out of five domains.ConclusionThe EBP2-N is a suitable instrument for measuring Norwegian primary healthcare professionals’ EBP knowledge, attitudes, confidence, and behavior. Although EBP2-N seems to be an adequate instrument in its current form, we recommend that future research focuses on further assessing the factor structure, evaluating the relevance of the items, and the number of items needed.RegistrationRetrospectively registered (prior to data analysis) in OSF Preregistration. Registration DOI: https://doi.org/10.17605/OSF.IO/428RP.

Ultrafine PtFeMo intermetallic compound nanowires for efficient oxygen reduction reaction in proton exchange membrane fuel cells

To advance the application of proton exchange membrane fuel cells (PEMFCs), it is crucial to develop high-performance oxygen reduction reaction (ORR) catalyst. Pt-based alloy nanowires exhibit excellent ORR activity due to their unique one-dimensional structure, but transition metals undergo spontaneous leaching under the harsh operating condition, often leading to decreased activity. Herein, ultrafine PtFeMo intermetallic compound nanowires were successfully synthesized as a high-performance ORR catalyst for PEMFC. The average diameter of the nanowires was 2.1 nm and the incorporation of inexpensive and high melting point metal Mo improved both catalytic performance and structural stability. The as-prepared ultrafine PtFeMo intermetallic compound nanowires exhibited mass activity of 2.56 A mgPt−1 for ORR, which is higher than that of disordered PtFeMo alloy nanowires (1.36 A mgPt−1) and commercial Pt/C (0.24 A mgPt−1) in rotating disk electrode test. And it exhibited peak power density of 2716 mW cm−2 under 250 kPa H2-O2 single-cell and mass activity of 0.62 A mgPt−1 under 100 kPa H2-O2 single-cell test in PEMFC. After long-time durability test, the intermetallic compound nanowires maintained their original structure, composition and electrocatalytic performance well, highlighting the importance of Mo incorporation and ordered phase structure generation.

Improved flame retardancy and mechanical properties of bacterial cellulose fabrics via solvent exchange and entrapment of zein and gluten

This study aimed to improve the flame retardancy and mechanical properties of bacterial cellulose (BC) by introducing cereal proteins, namely zein and gluten. The production conditions were determined by observing residual masses of samples at 1000 ℃ using thermogravimetric analysis (TGA). According to the TGA results, the optimized production conditions for the BCs with zein and gluten were combined solvent exchange and entrapment of 20 weight% (wt.%) of zein, and entrapment of 40 wt.% of gluten, respectively. Surface characterization of BC prepared with zein and gluten under the optimal conditions confirmed that the cereal proteins were incorporated into the BC nanostructures via solvent exchange and/or entrapment and the original chemical and crystal structures of BC were not significantly changed. Limiting oxygen index (LOI) analysis confirmed that cereal proteins improved the flame retardancy of BC. In particular, the LOI of BC entrapped with gluten was 50%, which was better than that of cowhide leather. Char morphology analysis confirmed that the as-produced BCs with cereal proteins exhibited condensed-phase flame-retardant mechanism by forming intumescent chars. Analysis of the mechanical properties confirmed that compared with cowhide leather, as-produced BCs with cereal proteins possessed high tensile strength and dimensional stability, making them suitable leather substitutes.

Plasmodium falciparum population dynamics in East Africa and genomic surveillance along the Kenya-Uganda border

East African countries accounted for ~ 10% of all malaria prevalence worldwide in 2022, with an estimated 23.8 million cases and > 53,000 deaths. Despite recent increases in malaria incidence, high-resolution genome-wide analyses of Plasmodium parasite populations are sparse in Kenya, Tanzania, and Uganda. The Kenyan-Ugandan border region is a particular concern, with Uganda confirming the emergence and spread of artemisinin resistant P. falciparum parasites. To establish genomic surveillance along the Kenyan-Ugandan border and analyse P. falciparum population dynamics within East Africa, we generated whole-genome sequencing (WGS) data for 38 parasites from Bungoma, Western Kenya. These sequences were integrated into a genomic analysis of available East African isolate data (n = 599) and revealed parasite subpopulations with distinct genetic structure and diverse ancestral origins. Ancestral admixture analysis of these subpopulations alongside isolates from across Africa (n = 365) suggested potential independent ancestral populations from other major African populations. Within isolates from Western Kenya, the prevalence of biomarkers associated with chloroquine resistance (e.g. Pfcrt K76T) were significantly reduced compared to wider East African populations and a single isolate contained the PfK13 V568I variant, potentially linked to reduced susceptibility to artemisinin. Overall, our work provides baseline WGS data and analysis for future malaria genomic surveillance in the region.

Finite Element Method-Peridynamics Coupled Analysis of Slope Stability Affected by Rainfall Erosion

Rainfall is a pivotal factor resulting in the cause of slope instability. The traditional finite element method often fails to converge when dealing with the strongly nonlinear fluid–solid coupling problems, making it impossible to fully analyze the sliding process under the state of slope instability. Therefore, this paper uses the coupling of peridynamics (PD) and the finite element method (FEM) to propose a data exchange mode between the seepage field and the deformation field. The influencing factors of fine particle erosion during rainfall are further considered. According to the damage mechanism of the slope sliding process to the original structure of the soil, a modified erosion constitutive relationship is proposed, which takes into account the destructive effect of plastic deformation on coarse particles. Then, the influence of rainfall duration, rainfall intensity, erosion, and initial saturated permeability coefficient on slope stability was simulated and analyzed. This paper provides a novel concept for slope stability analysis and safety evaluation under rainfall conditions.

A Global Feature Reused Network for Defect Detection in Steel Images

Abstract Accurate detection of surface defects for steel is essential to improve surface quality and service life. Deep learning (DL) used in steel surface defect detection can solve the problems of low efficiency and poor accuracy of traditional manual detection. The classic YOLOv5 acted as a DL method is used to accomplish defects detection task without attention mechanisms, resulting in a loss of global information. Besides, it is difficult to complete complex network detection tasks with low configuration hardware, especially for surface defects with complex defect types and variable defect sizes. To solve these issues, this paper introduces an improved Global Feature Reuse and Hardware-Aware YOLOv5 by using BoTNet, RepGhost, and EfficientRep model (BGE-YOLOv5). The Multi-Head Self-Attention (MHSA) layer is used to obtain global information and only part of convolutional layers (CL) are replaced to avoid excessive computational cost. The RepGhost model is introduced to extract remaining feature information for feature reuse. EfficientRep is used to replace the original structure to achieve hardware-aware and to balance the detection veracity and efficiency. The Distance IoU (DIOU) is replaced by SCYLLA-IoU (SIOU) to accelerate the iteration and improve stability. The results of the framework on surface defect database (NEU-DET) show that BGE-YOLOv5 achieves a mean average precision (mAP) of 79.5%, which is 10.3% greater than the baseline. The proposed BGE-YOLOv5 has a better performance in steel surface defects detection.

Factors affecting conversion of methane-hydrogen mixtures into nanostructured carbon and hydrogen

At the catalytic decomposition of methane, along with hydrogen, it is possible to obtain carbon nanofibers. The addition of hydrogen to the initial reaction mixture makes it possible to increase significantly the efficiency of the overall process by minimizing the contribution of the catalyst deactivation process caused by coking. As found, the maximum yields of hydrogen and nanostructured carbon over the NiO–CuO/Al2O3 catalyst is achieved at an inlet hydrogen concentration of 13 vol%. The accumulated carbon is represented by well-structured carbon nanofibers, which are resistant to the gasification reaction. The original stacked structure is preserved after the treatment of these fibers in a hydrogen medium. Using numerical methods, the hydrogen productivity at 610 °C was found to be 49.3 mL/(mgcat·h) at an optimal value of the residence time of 5 × 10−3 s.

Robust multi-view clustering via structure regularization concept factorization

Recently, many concept factorization-based multi-view clustering methods have been proposed and achieved promising results on text multi-view data. However, existing methods are limited in the following two aspects. (1) The Frobenius norm used in these methods is sensitive to noise and outliers; (2) These methods ignore the global structural information of the data. To address the above problems, we propose a robust concept factorization framework for multi-view clustering, which not only improves the robustness but also fully exploits the available information of multi-view data. Specifically, L2,1-norm is used to evaluate the error of the factorization, thus eliminating the effect of outliers and improving robustness. In addition, to retain more structure information of the original data, the global and local structure information are taken into consideration simultaneously, which makes the learned low-dimensional matrix more discriminative. Further, to make use of the complementary information of the different views, we introduce an adaptive weight learning strategy to assign weights for different views. An iterative updating algorithm is proposed to solve the proposed optimization problem. We compare the proposed method with state-of-the-art alternative methods on benchmark multi-view data sets. The extensive experimental results show the effectiveness and superiority of the proposed method.

Upper blepharoplasty in Asian population: A novel technique based on functional zoning and dynamic reconstruction with anatomical structure.

Double eyelid blepharoplasty is the most popular cosmetic operation in Asian population. Various surgical techniques have been developed in order to create dynamic eyelid folds with natural-looking in recent years, but postoperative complications like so-called sausage-like appearance have not been resolved completely. To create natural-looking dynamic folds, we propose a new method imitating the original anatomical structure of congenital double-eyelid. Eighty-six patients who underwent the double-eyelid surgery from June 1st, 2018 to October 31st, 2020 were included in this retrospective study, including 10 males and 76 females, aged 18-39 years (mean 27.4 ± 5.6 years). All the included patients received double eyelid surgery performed by the same senior doctor, using the pretarsal orbicularis oculi muscle-releasing technique. Patient Reported Outcome Measures questionnaires were administrated to assess the severity of scarring, pain, and asymmetry, as well as functional and appearance issues. Surgical outcome was assessed through objective and subjective evaluation forms (PROM and patient satisfaction rate). Among the 86 patients, 5 were lost during the follow-up period. The absolute number of enrolled patients is 81. 91.36% of the enrolled patients reported minimal or non-visible scarring at the double eyelid incision. As to functional and appearance issues, the main problem were asymmetry (12.35%) and the narrowing of the supratarsal crease width (8.64%). No supratarsal depression and "sausage-like" appearance occurred in this study. 95.1% of patients reported either good or excellent outcome (mean score: 108 of 120) based on analysis of PROM results, and 96.3% of patients reported either high or very high satisfaction (mean score: 96 of 120) for the patient satisfaction assessment. This new surgical method of double-eyelid blepharoplasty provides comparatively safe and effective results.

Psychometric Support and Measurement Invariance of a Turkish Version of the Transformational Parenting Questionnaire.

Our primary objective in this study was to psychometrically evaluate the Transformational Parenting Questionnaire (TPQ) within the Turkish context. Secondarily, we aimed to determine whether the questionnaire demonstrated measurement invariance across children's genders and grade levels. We included 950 participants, aged 11-18years (446 girls, 498 boys, 6 unspecified gender identity; Mage = 14.73, SD = 1.85years). Confirmatory factor analysis provided support for the original 4-factor structure of the TPQ, and there was satisfactory criterion-related correlational validity between this instrument and the Satisfaction with Life Scale. The TPQ exhibited robust internal item reliability coefficients, and respondent's test-retest correlations over a 15-day interval suggested adequate item response consistency. Importantly, we confirmed measurement invariance of the scale across participants gender and educational grade levels. In summary, we found that the TPQ was a valid and reliable tool for assessing Turkish children's perceptions of transformative parenting behaviors.

Correlation between Soil Moisture Change and Geological Disasters in E’bian Area (Sichuan, China)

E’bian Yi Autonomous County is a mineral-rich area located in a complex geological structure zone. The region experiences frequent geological disasters due to concentrated rainfall, steep terrain, and uneven vegetation cover. In particular, during the rainy season, large amounts of rainwater rapidly accumulate, increasing soil moisture and slope pressure, making landslides and debris flows more likely. Additionally, human activities such as mining, road construction, and building can alter the original geological structure, exacerbating the risk of geological disasters. According to publicly available data from the Leshan government, various types of geological disasters occurred in 2019, 2020, 2022, and 2023, resulting in economic losses and casualties. Although some studies have focused on geological disaster issues in E’bian, these studies are often limited to specific areas or types of disasters and lack comprehensive spatial and temporal analysis. Furthermore, due to constraints in technology, funding, and manpower, geophysical exploration, field geological exploration, and environmental ecological investigations have been challenging to carry out comprehensively, leading to insufficient and unsystematic data collection. To provide data support and monitoring for regional territorial spatial planning and geological disaster prevention and control, this paper proposes a new method to study the correlation between soil moisture changes and geological disasters. Six high-resolution Landsat remote sensing images were used as the main data sources to process the image band data, and terrain factors were extracted and classified using a digital elevation model (DEM). Meanwhile, a Normalized Difference Vegetation Index–Land Surface Temperature (NDVI-LST) feature space was constructed. The Temperature Vegetation Drought Index (TVDI) was calculated to analyze the variation trend and influencing factors of soil moisture in the study area. The research results showed that the variation in soil moisture in the study area was relatively stable, and the overall soil moisture content was high (0.18 < TVDI < 0.33). However, due to the large variation in topographic relief, it could provide power and be a source basis for geological disasters such as landslide and collapse, so the inversion value of TVDI was small. The minimum and maximum values of the correlation coefficient (R2) were 0.60 and 0.72, respectively, indicating that the surface water content was relatively large, which was in good agreement with the calculated results of vegetation coverage and conducive to the restoration of ecological stability. In general, based on the characteristics of remote sensing technology and the division of soil moisture critical values, the promoting and hindering effects of soil moisture on geological hazards can be accurately described, and the research results can provide effective guidance for the prevention and control of geological hazards in this region.

A comprehensive review of antimicrobial peptides: Mechanisms, classifications and designations

Antimicrobial peptides (AMPs) are a group of alkaline poly-peptide compounds that have antibacterial activity and are produced by insects. This research examines three key aspects of antimicrobial peptides (AMPs): their mechanism of action, categorization, and designation. Antimicrobial peptides have a wide range of antimicrobial action, with a significant number of them being naturally occurring peptides. Consequently, they are increasingly being recognized as promising candidates for therapeutic applications. Antimicrobial peptides can be categorized into many categories based on their structural characteristics and origin. The field of computer-assisted peptide design integrates computer-aided design technology with the process of drug creation, so leveraging its inherent benefits and offering a rational and efficient theoretical framework for the design of peptides. The identification of novel classes of antibiotics is a promising approach for addressing the issue of antibiotic resistance. Antimicrobial peptides possess significant potential for application within the pharmaceutical sector due to their notable antibacterial efficacy, extensive range of antibacterial activity, diverse structural characteristics, and extensive array of options. Moreover, these peptides have a reduced likelihood of inducing resistance mutations in target strains. Currently, a number of poly-peptide antibiotics are being subjected to preclinical feasibility investigations. One of these antibiotics, magainins, has progressed to the phase III clinical trial stage.

Structural origin of enhanced storage energy performance and robust mechanical property in A-site disordered high-entropy ceramics

Structural origin of enhanced storage energy performance and robust mechanical property in A-site disordered high-entropy ceramics

Achieving excellent mechanical and robust lubrication behavior in the CoCrNi medium-entropy alloy via in-situ graphite

The unsatisfactory wear resistance and lubrication performance of CoCrNi multi-principal elements alloys (MPEAs) have emerged as critical challenges, impeding their extensive utilization as advanced engineering materials, despite their desirable mechanical and physical properties. Incorporating graphite to obtain MPEAs-based self-lubricating composites is believed to improve the wear resistance. However, it is challenging to prepare composites with high strength, large plasticity, and excellent anti-friction performance simultaneously. The present study reports the fabrication of novel CoCrNi MPEA-based self-lubricating composites, consisting of in-situ graphite and high-hardness silicides/carbides as reinforcement, prepared by powder metallurgy and reactive sintering. The 20.6 vol% Gr@CoCrNi–SiC composite exhibits an optimal trade-off between strength and ductility, along with anti-friction and wear resistance which is superior to the reported composites with different solid lubricants. The wear mechanism is attributed to the coordinated deformation mechanism between the CoCrNi FCC matrix and silicides/carbides, and the stabile lubrication effect supported by the structural transformation from the original polycrystalline lattice structure to core-shell nanocomposite structure (similar to diamond-like carbon) of the in-situ graphite. This simple, economical and practical strategy contributes to the development of MPEA self-lubricating composites with excellent comprehensive properties.

Evaluation of the use of polyvinyl alcohol in the manufacture of pressed samples for X-ray fluorescence analysis

The reliability of the results of X-ray fluorescence analysis (XRF), which is widely used in determination of the elemental composition of various materials, largely depends on the quality of sample preparation. When producing pressed tablets for X-ray fluorescence analysis of trace elements, a binder is often used in a powder form, which requires significant time for thorough homogenization. We present the results of applicating a polyvinyl alcohol solution as a binder in the manufacture of pressed samples without using a substrate in determination of microelements by XRF. The parameters for obtaining a durable tablet with a homogeneous composition that matches the condition of minimum impact on the intensity of the analytical lines of the elements being determined are presented. It is shown that the optimal sample weight for the proposed method of producing pressed tablets is 7 g with the addition of polyvinyl alcohol in a ratio of 7:1, the optimal drying time for the tablet after pressing is 1 hour. The calculated variation coefficients of the analytical signal (<2%) indicate the homogeneity of the produced tablets. The maximum values of standard deviations of pressed tablets for the selected ranges of elements are much less than acceptable, which confirms the validity of the proposed method of sample preparation. It is also shown that during long-term storage and repeated measurements, pressed tablets with the polyvinyl alcohol solution retain their original structure and intensity of analytical lines of elements. The accuracy of measurements in the subsequent determination of rock-forming elements is consistent with their certified contents. The results obtained can be used to reduce the time spent on getting a representative pressed sample when using polyvinyl alcohol, determining elements without additional support (coating films), microelement and silicate analyzes from one sample.

Accelerated multistep thermal stabilization of polyacrylonitrile fibers using an ethylenediamine pretreatment

The polyacrylonitrile multifilament yarn underwent a multistep heat treatment process including stabilization times ranging from 5 to 75 min following impregnation with a 30% ethylenediamine (EDA) aqueous solution. A series of measurements were employed to determine the structure and properties of thermally stabilized PAN samples. These included fiber thickness, fiber density, flame testing, tensile testing, X-ray diffraction, thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and infrared spectroscopy. The results from XRD and IR spectroscopy indicated that the rate of aromatization reactions increased with longer stabilization times. A detailed examination of the XRD curves obtained through curve-fitting procedures suggested a rapid transformation of the original structure into a disordered amorphous phase containing pre-graphitic domains, evidenced by a gradual reduction in the degree of apparent crystallinity of the original PAN sample. The integration of EDA before the thermal stabilization stage significantly reduced the cyclization time of nitrile groups in the PAN polymer structure, thereby accelerating the stabilization reactions. This chemical pretreatment also improved the thermal stability of the samples by promoting oxidative cross-linking of the PAN polymer chains. After a 75 min multistep stabilization, the carbon yield at 1000 °C was 70.5%. Conversion index values, calculated using IR, XRD, and DSC methods, were 98.3%, 94.8%, and 89.5% respectively for the 75 min sample. These findings highlight the importance of EDA in accelerating the formation of an aromatic structure, which is critical for withstanding the high temperatures of subsequent carbonization stages.Graphical abstract

Optimization of spherically arranged lens arrays based on class II and III geodesic polyhedra

Spherical arrangement is a common way to pack lens arrays. Due to the restriction of original structures, the previous optimization methods based on icosahedral subdivision are only applicable to a few types of lens arrays adopting different numbers of sub-lenses. In order to design more types of lens arrays, an optimization packing method is proposed with the vertices of class II and class III geodesic polyhedra as the arrangement positions of sub-lenses. The vertices of the geodesic polyhedron are generated by projecting grid nodes on each face of the ortho-icosahedron to a sphere. The vertex translation function is established in a barycentric coordinate system, and then the chord ratio and packing density are used as evaluation functions to optimize the vertices’ positions. The universality of the optimization method is tested, and its robustness is certified by analyzing the optimization results of different original structures with the same number of vertices. Finally, the effectiveness and feasibility of the optimization method in engineering applications are demonstrated in a monocentric multi-scale imaging system. The optimization method proposed in this paper can significantly increase the types of lens arrays from 9 to 37 types, adopting different numbers of sub-lenses within 1000 and effectively improved the distribution uniformity of lens arrays.