bluuebunny/crossref_metadata_2025 huggingface dataset:
Spinal column and midbrain integration for long duration space missions
Authors: Richardson Tauhid
Published: August 2023

Background:  Deep space missions produce atrophied postural muscles and cognitive and proprioception losses. Lumbar and hip injury as well as limbic system dysregulation may result.  In microgravity, the Neutral Body Position is the spinal baseline for the prone-position cycle, where the astronaut’s lumbar muscles and audio and visual-spatial centers can be informed through a virtual reality interface.

Methods: The exercise can be reproduced as a low-fidelity space simulation in a epsom-salt float tank. MRI and ultrasound imaging of the spine at the start of the 4-week program can be compared to the imaged results upon program completion.  Any contractile tightening would be evident in shortened IVD (intervertebral distances) in post-procedure MRI results. The terrestrial gravity cycling instrument  establishes an effective baseline for determining anthropomorphic tolerances, the necessary workout duration and resistance levels in zero gravity.

Results: An exercise regimen performed on an ergonomically-designed cycle can limit the stresses to demineralized postural bones thus reducing the risk of in-flight and post-flight fractures.  The redistribution of spinal fluids is a specific focus of this exercise instrument.  It's postulated that the secondary effect of reduced spinal fluid shifts are lower optic nerve and cranial pressures and the tertiary effect is the reduction of neuro-cognitive and cardio-vascular stresses brought on by weightlessness.  

Conclusions: The biomechanism of spinal fluid’s dynamic flow across a lower pressure gradient may be the cause of increased fluid volume in the spinal canal. This cycling exercise lessens the physical impact to areas of BMD depletion such as the hip socket.  The exercise can maintain spinal flexibility, fluid stasis and posture.   Human body systems affected by microgravity could be assisted with Virtual Reality (VR) inputs.  The limbic system receives comprehensive, targeted sensory information that enables reorganization of neuronal networks that may serve to change dysregulated human immune, spatio-temporal, and cognitive systems.
Benchmarking graph representation learning algorithms for detecting modules in molecular networks
Authors: Song Zhiwei , Baur Brittany , Roy Sushmita
Published: August 2023

Background: A common task in molecular network analysis is the detection of community structures or modules. Such modules are frequently associated with shared biological functions and are often disrupted in disease. Detection of community structure entails clustering nodes in the graph, and many algorithms apply a clustering algorithm on an input node embedding. Graph representation learning offers a powerful framework to learn node embeddings to perform various downstream tasks such as clustering. Deep embedding methods based on graph neural networks can have substantially better performance on machine learning tasks on graphs, including module detection; however, existing studies have focused on social and citation networks. It is currently unclear if deep embedding methods offer any advantage over shallow embedding methods for detecting modules in molecular networks.

Methods: Here, we investigated deep and shallow graph representation learning algorithms on synthetic and real cell-type specific gene interaction networks to detect gene modules and identify pathways affected by sequence nucleotide polymorphisms. We used multiple criteria to assess the quality of the clusters based on connectivity as well as overrepresentation of biological processes.

Results: On synthetic networks, deep embedding based on a variational graph autoencoder had superior performance as measured by modularity metrics, followed closely by shallow methods, node2vec and Graph Laplacian embedding. However, the performance of the deep methods worsens when the overall connectivity between clusters increases. On real molecular networks, deep embedding methods did not have a clear advantage and the performance depended upon the properties of the graph and the metrics.

Conclusions: Deep graph representation learning algorithms for module detection-based tasks can be beneficial for some biological networks, but the performance depends upon the metrics and graph properties. Across different network types, Graph Laplacian embedding followed by node2vec are the best performing algorithms.
Morphological, structural, chemical, vibrational, thermal, pasting, and functional changes in pea starch during germination process
Authors: Lucas-Aguirre Juan Carlos , Quintero-Castaño Víctor Dumar , Castañeda-Cano Luisa Fernanda , Rodríguez-García Mario Enrique
Published: August 2023

Background: Changes in the structural and physicochemical properties of pea starch could be significantly affected by germination treatment, which can provide a theoretical basis for promoting the use of this starch in the food industry.

Methods: This work aims to evaluate the effect of germination time on the structural, thermal, rheological and functional properties of pea starches to determine their potential in the production of fermented beverages. The physicochemical changes during the germination process of peas and native and germinated starch granules were evaluated.

Results: For germination critical time was 0.985 days, with 95% of germinated grains. The starch grains did not undergo any morphological change during the germination process as seen in the scanning electron microscopy images, indicating the absence of the α and ß - amylases responsible for the starch splitting. The X-ray patterns revealed that the crystalline structures of pea starch with and without germination were unchanged and contained by hexagonal and orthorhombic glucopyranose crystals. The viscosity profiles of the starches do not show significant changes; the most representative change is the increase in the gelatinization onset temperature of the paste from germinated starches compared to native starch. The functional properties of starches showed generally low values, with statistically significant differences between water absorption index, water solubility index, and starch swelling power and germination time.

Conclusions: In general terms, it can be concluded that lentil starch does not undergo significant changes in its physicochemical and functional integrity with respect to the grain germination process.
A prospective assessment of gait kinematics and related clinical examination measures in cerebral palsy crouch gait
Authors: O'Sullivan Rory , French Helen , Horgan Frances
Published: August 2023

Background

While prospectively assessed crouch gait in cerebral palsy (CP) does not necessarily progress, prospective changes in clinical examination measures have not been reported.

This study prospectively examined the association between selected clinical examination variables and change in crouch gait in a cohort with bilateral CP.

Methods

Inclusion criteria were a diagnosis of ambulant bilateral CP, knee flexion at mid-stance >19 0 and a minimum of two-years between gait analyses. The change in kinematic variables was assessed using Statistical Parameter Mapping (SPM) and changes in clinical measures using appropriate paired tests. Linear regression examined the association between progression of crouch and clinical examination variables.

Results

There was no mean change in crouch in 27 participants over 3.29 years. However, there was significant variability within this group. Clinical hamstring tightness (60.00 0 to 70.48 0, p<0.01) and external knee rotation during stance (SPM analysis, p<0.001) increased but there was no association between changes in clinical examination variables and changes in crouch (p-values 0.06 - 0.89).   

Conclusions

This prospective study found no association between the changes in clinical examination variables and changes in crouch highlighting the likely multi-factorial aetiology of this gait pattern and the need for larger prospective studies. The variability crouch gait progression among the 27 participants highlights the pitfall of group mean values in such a heterogeneous population.
Vitamin D - a key to reducing the risk of suicide?
Authors: Januszewski Jacek , Forma Alicja , Karakuła Kaja Hanna , Sitarz Ryszard , Baj Jacek , Kłodnicka Karolina , Zembala Julita , Juchnowicz Dariusz
Published: August 2023

Introduction: Vitamin D has a major positive impact on human health. Its daily supplementation regulates calcium metabolism, inflammatory and neuromodulatory processes. More importantly, vitamin D may be an important factor in reducing the risk of suicide among psychiatric patients. This review aims to describe the potential positive effect of vitamin D supplementation in preventing suicide attempts.
Method: The literature review was conducted by search of articles in English and Polish languages on PubMed, Medline, and Google Scholar, published from 1974 to the 1st of April 2023, following SANRA requirements. The search utilized the following keywords: vitamin D, vitamin D deficiency, vitamin D supplementation, suicide, depression, bipolar disorder, schizophrenia, ADHD, anxiety, and autism. The analysis encompassed original studies, meta-analyses, randomized controlled trials, and review articles.
Results: There is a limited number of studies investigating the impact of vitamin D supplementation on suicide risk in individuals with mental illness. Several studies suggest that vitamin D may have a beneficial effect on symptoms of mental illnesses. However, the exact mechanism through which vitamin D exerts its therapeutic effects on mental health remains unclear. Incorporating vitamin D into the treatment of the mental disorders such as depression, schizophrenia, bipolar disease, ADHS, autism spectrum disorder, and anxiety, as well as supplementing it during pregnancy and throughout life, could potentially be an effective therapeutic adjunct for suicide prevention approach.
Conclusions: According to all the research and gathered data, there is a correlation between Vitamin D supplementation and a decrease in suicide risk among patients suffering from mental disorders. Several lines of evidence have shown a positive impact on mental health in patients suffering from mental diseases. However, further research is needed to establish the mechanisms of the therapeutic effect of Vitamin D.

Keywords: vitamin D, vitamin D supplementation, suicide, psychiatric disorders
A 15-YEAR SURVIVAL ANALYSIS OF OXIDIZED ZIRCONIUM TOTAL KNEE ARTHROPLASTY
Authors: Fennelly Joseph , Santini Alasdair , Papalexandris Stylianos , Pope Jill , Yorke Joanne , Davidson John
Published: August 2023

Background

Oxidized zirconium (OxZr) has been introduced as an alternative bearing for femoral components in Total Knee Arthroplasty (TKA). It has a ceramic-like zirconium oxide outer layer with a low coefficient of friction. Early studies have found OxZr TKA to have a low incidence of early failure in young high demand patients. Currently no study has reported on the outcome of these implants beyond ten years.

Objectives

The purpose of our study was to present an in-depth 15-year survival analysis of cemented Profix II OxZr TKA.

Study Design & Methods

Data was collected prospectively and survival analysis undertaken with multiple strict end points. Complication rates were recorded and patient reported outcomes were measured.

Results

617 Profix II OxZr TKAs were performed over four years. Forty-nine patients underwent reoperation. Aseptic tibial loosening was the most common cause of failure (32.7%) on average occurring 2.8 years post primary procedure. There was one recorded failure due to loosening of the zirconium femoral component. Revision rate at 15-years was 6.38%. Cumulative survivorship was 91.52% with failure considered to be reoperation for any reason. WOMAC score improved in 86% of patients by year 1. The average score improved by 21.2 points and met the standard for minimum clinically important difference.

Conclusions

This study presents the first 15-year survival analysis of cemented Profix II OxZr TKA. Our data supports current literature on the long-term survivorship of oxidised zirconium total knee replacements.
POLYETHYLENE BEARING WEAR OF THE OXFORD UNICOMPARTMENTAL KNEE ARTHROPLASTY: TEN-YEAR RESULTS OF A RANDOMIZED CONTROLLED TRIAL COMPARING CEMENTED AND CEMENTLESS FIXATION
Authors: Arthur Lachlan , Ghosh Priyanka , Mohammad Hasan , Campi Stefano , Murray David , Mellon Stephen
Published: August 2023

Introduction

The Oxford Unicompartmental Knee Replacement's (OUKR's) fully-congruent design minimises polyethylene wear. Consequently, wear is a rare failure mechanism. Phase-3 OUKR linear wear at 5 years was higher than previous OUKR phases, but very low compared to fixed-bearing UKRs. This study aimed to measure OUKR bearing wear at 10 years and investigate factors that may affect wear.

Methodology

Bearing thickness for 39 OUKRs from a randomised study was calculated using radiostereometric analysis at regular intervals up to 10 years. Data for 39 and 29 OUKRs was available at 5 and 10 years, respectively. As creep occurs early, wear rate was calculated using linear regression between 6 months and 10 years. Relationships between wear and patient factors, fixation method, Oxford Knee Score (OKS), bearing position, and component position were analysed.

Results

The mean wear rate was 0.06mm/year. Fixation method, age, OKS, component size, and bearing size had no correlation with wear. A higher BMI was associated with lower wear (p=0.01). Bearings more than 4mm from the wall had significantly more wear (p=0.04) than those less than 4mm from the wall. There was a linear correlation between the femoral component contact area on the bearing and wear (p=0.04).

Conclusions

Phase-3 bearing wear rate is constant, significantly higher than previous OUKR phases at 10 years, and may increase the risk of long-term bearing failure. To minimise complications associated with wear, size 4 bearings should be used in young patients and manufacturing bearings from more durable, highly crosslinked polyethylene should be studied.
REST: A PROSPECTIVE RANDOMIZED FEASIBILITY STUDY ASSESSING THE IMPACT OF A TAILORED SLEEP INTERVENTION IN PATIENTS UNDERGOING TOTAL KNEE ARTHROPLASTY
Authors: Bertram Wendy , Wylde Vikki , Glynn Joel , Penfold Chris , Burston Amanda , Johnson Emma , Rayment Dane , Howells Nick , White Simon , Gooberman-Hill Rachael , Whale Katie
Published: August 2023

Introduction

There is a need to develop approaches to reduce chronic pain after total knee replacement. There is an established link between disturbed sleep and pain. We tested the feasibility of a trial evaluating the clinical and cost-effectiveness of a pre-operative sleep assessment and complex intervention package for improving long-term pain after TKR.

Methodology

REST was a feasibility multi-centre randomised controlled trial with embedded qualitative study and health economics. Participants completed baseline measures and were randomised to usual care or the intervention, a tailored sleep assessment and behavioural intervention package delivered by an extended scope practitioner three months pre-operatively with a follow-up call up at four-weeks. Patient reported outcomes were assessed at baseline, one-week pre-surgery, and 3-months post-surgery.

Results

57 patients were randomised and 20 had surgery within the study timelines. All patients allocated the intervention attended an appointment and most engaged with treatment. The intervention group reported improvements in sleep (Sleep Conditions Indicator) and neuropathic pain (painDETECT) scores. Participants found the sleep treatments and study processes to be acceptable. The mean cost of the intervention was estimated at £134.45 per patient.

Conclusion

The feasibility study has shown that patient recruitment is feasible, engagement with and adherence to the intervention is high, and the intervention is acceptable to patients and clinicians. Preliminary findings show that the intervention group had improved sleep quality and had reduced levels of pre-operative neuropathic pain. This study has demonstrated that a full RCT is feasible and identified areas for improvement to optimize the trial design.
DOES OBESITY HAVE AN EFFECT ON PATIENT OUTCOMES AND PLATE SURVIVORSHIP IN HIGH TIBIAL OSTEOTOMY SURGERY? THE TOMOFIX ANATOMICAL MEDIAL HIGH TIBIAL PLATE
Authors: Nicholls Kate , Petsiou Dioni , Wilcocks Katharine , Shean Katharine , Anderson James , Vachtsevanos Leonidas
Published: August 2023

Introduction

Surgery in patients with high body mass index (BMI) is more technically challenging and associated with increased complications post-operatively. Inferior clinical and functional mid-term results for high BMI patients undergoing high tibial osteotomy (HTO) relative to normal weight patients have been reported. This study discusses the clinical, radiological and functional outcomes of HTO surgery in patients with a high BMI.

Method

This is a retrospective study on patients undergoing HTO surgery using the Tomofix anatomical MHT plate between 2017 and 2022, with follow-up period of up to 5 years. The cohort was divided: non-obese (BMI <30 kg/m2) and obese (BMI>30 kg/m2). Pre and post operative functional scores were collected: Oxford Knee Score (OKS), EuroQol-5D and Tegner. Complications, plate survivorship and Mikulicz point recorded.

Results

32 HTO procedures; 19 patients BMI <30 (average 27.0) and 14 patients BMI >30 (average 36.1). In BMI<30 cohort, one readmission for investigation of venous thromboembolism, doppler negative; two complications: hinge fracture and stitch abscess. The five year survivorship of the plate was 100%. In BMI>30 cohort, one readmission for pulmonary embolism; one complication: hinge fracture. The 5 year survivorship of the plate was 93%, 1 conversion to unicompartmental knee replacement. The average OKS improvement was 17 and 18 for BMI <30 and >30 respectively. Mikulicz point change was identical.

Conclusion

The Tomofix anatomical MHT plate achieves good outcomes and minimal complications irrespective of BMI. Reduced plate survivorship, thus earlier conversion may be required in the obese, however higher cohort numbers are needed to confirm this.
A REVISION ARTHROPLASTY NETWORK HAS SIGNIFICANTLY REDUCED EARLY RE-REVISION RATES FOLLOWING REVISION TOTAL KNEE ARTHROPLASTY COMPARED WITH THE REST OF ENGLAND: AN ANALYSIS OF THE EAST MIDLANDS SPECIALIST ORTHOPAEDIC NETWORK USING A NATIONAL ADMINISTRATIVE DATA SET
Authors: Bloch Benjamin , Berber Reshid , Matar Hosam , James Peter , Manktelow Andrew
Published: August 2023

Introduction

Revision total knee arthroplasty (RTKA) is a complex procedure with higher rates of re-revision, complications and mortality compared to primary TKA. We report the effects of the establishment of a Revision Arthroplasty Network (The East Midlands Specialist Orthopaedic Network; EMSON).

Methodology

The Revision Arthroplasty Network was established in January 2015 and covered the Nottinghamshire and Lincolnshire areas of England. This comprises a collaborative weekly multidisciplinary meeting where upcoming RTKA procedures are discussed, and a plan agreed.

Using the Hospital Episode Statistics database, RTKA procedures carried out between 2011 and 2018 from the five EMSON hospitals were compared to all other hospitals in England. Age, sex, and Hospital Frailty Risk scores were used as covariates.

The primary outcome was re-revision surgery within 1 year of the index revision. Secondary outcomes were re-revision surgery within two years, any complication within one and two years and median length of stay.

Results

33,828 RTKA procedures were performed across England; 1,028 (3.0%) were conducted within EMSON. Re-revision rates within 1 year were 11.6% and 7.4% pre- and post-intervention respectively within the network. This compares to a pre-post change from 11.7% to 9.7% for the rest of England. In comparative interrupted time-series analysis, there was a significant immediate improvement in re-revision rates for EMSON hospitals compared to the rest of England at 1 year (p = 0.024) and 2 years (p=0.032).

Conclusion

Re-revision rates for RTKA improved significantly at one and two years with the introduction of EMSON, when compared to the rest of England.
FOCAL RESURFACING OF THE KNEE: A SYSTEMATIC REVIEW AND META-ANALYSIS
Authors: Mikova Ester , Kunutsor Setor , Butler Meg , Murray James
Published: August 2023

Introduction

Active, middle-aged patients with symptomatic cartilage or osteochondral defects can find themselves in a treatment gap when they have failed conservative measures but are not yet eligible for conventional arthroplasty. Data from various cohort studies suggests that focal knee resurfacing implants such as HemiCAP, UniCAP, Episealer or BioBoly are cost-effective solutions to alleviate pain, improve function and delay or eliminate the need for conventional replacement. A systematic review and meta-analysis were conducted in order to(i) evaluate revision rates and implant survival of focal resurfacing; (ii) explore surgical complications; and (iii) evaluate various patient reported clinical outcome measures.

Methodology

PubMED, Cochrane Library and Medline databases were searched in February 2022 for prospective and retrospective cohort studies evaluating any of the available implant types. Data on incidence of revision, complications and various patient reported outcome measures was sourced.

Results

A total of 24 unique studies were identified with a total of 1465 enrolled patients. A revision rate of 12.97% over a 5.9 year weighted mean follow-up period was observed across all implant types. However, in one series a Kaplan-Meir survival as high as 92.6% at a 10-year follow-up period was noted. A statistically significant improvement was documented across multiple subjective clinical outcomes scores. There was a low reported incidence of post-operative complications such as aseptic loosening or deep wound infection.

Conclusions

Focal femoral resurfacing appears to be a viable treatment option for focal symptomatic chondral lesions in patients beyond biological reconstruction, with low revision rates and high patient satisfaction.
THE MENISCAL TEAR OUTCOME (METRO) STUDY: A PROSPECTIVE NATIONAL COHORT STUDY EXPLORING THE OUTCOMES OF PATIENTS WITH A MENISCAL TEAR
Authors: Ahmed Imran , Dhaif Fatema , Bowes Mike , Parsons Nicholas , Hutchinson Charles , Staniszewska Sophie , Price Andrew , Metcalfe Andrew
Published: August 2023

Introduction

Previous research has demonstrated no clinically significant benefit of arthroscopic meniscectomy in patients with a meniscal tear, however, patients included in these studies would not meet current treatment recommendations. Prior to further randomised controlled trials (RCTs) research is needed to understand a younger population in more detail.

Aim

To describe the baseline characteristics of patients with a meniscal tear and explore any association between baseline characteristics and outcome.

Methodology

A prospective, national multicentre cohort study was performed recruiting patients aged 18 to 55 presenting to secondary care. MRI analysis of arthritis was performed using Whole Organ Magnetic Resonance Imaging Score (WORMS) and bone shape analysis. Outcomes included the Western Ontario Meniscal Evaluation Tool (WOMET) and Knee Injury and Osteoarthritis Outcome Score (KOOS4) at 12 months.

Results

150 participants were recruited across eight sites with a mean age of 43.47 (SD 9.63). MRI analysis using WORMS score and bone shape analysis revealed no or early osteoarthritis. At 12 months, 67 (44.67%) of participants were managed non-operatively and 68 (45.33%) were operatively. Participants in the operative group were significantly younger with a lower BMI (p<0.05). A stepwise logistic regression model including 17 characteristics revealed that only baseline score and surgery significantly affected 12-month WOMET and KOOS4.

Conclusion

This study in contrast to previous trials demonstrated a benefit of surgery for patients with a meniscal tear. The METRO study demonstrates that it is feasible to recruit younger patients and a future RCT is required using the study population included in this cohort.
Low-light image enhancement based on Retinex-Net with color restoration
Authors: Feng Wei , Wu Guiming , Zhou Shiqi , Li Xingang
Published: August 2023

Low-light images often suffer from a variety of degradation problems such as loss of detail, color distortions, and prominent noise. In this paper, the Retinex-Net model and loss function with color restoration are proposed to reduce color distortion in low-light image enhancement. The model trains the decom-net and color recovery-net to achieve decomposition of low-light images and color restoration of reflected images, respectively. First, a convolutional neural network and the designed loss functions are used in the decom-net to decompose the low-light image pair into an optimal reflection image and illumination image as the input of the network, and the reflection image after normal light decomposition is taken as the label. Then, an end-to-end color recovery network with a simplified model and time complexity is learned and combined with the color recovery loss function to obtain the correction reflection map with higher perception quality, and gamma correction is applied to the decomposed illumination image. Finally, the corrected reflection image and the illumination image are synthesized to get the enhanced image. The experimental results show that the proposed network model has lower brightness-order-error (LOE) and natural image quality evaluator (NIQE) values, and the average LOE and NIQE values of the low-light dataset images can be reduced to 942 and 6.42, respectively, which significantly improves image quality compared with other low-light enhancement methods. Generally, our proposed method can effectively improve image illuminance and restore color information in the end-to-end learning process of low-light images.
Fast laser field reconstruction method based on a Gerchberg–Saxton algorithm with mode decomposition
Authors: Moulanier I. , Dickson L. T. , Massimo F. , Maynard G. , Cros B.
Published: August 2023

Knowledge of the electric field of femtosecond, high intensity laser pulses is of paramount importance to study the interaction of this class of lasers with matter. A hybrid method to reconstruct the laser field from fluence measurements in the transverse plane at multiple positions along the propagation axis is presented, combining a Hermite–Gauss mode decomposition (MD) and elements of the Gerchberg–Saxton algorithm (GSA). The proposed GSA-MD takes into account the pointing instabilities of high intensity laser systems by tuning the centers of the HG modes. Furthermore, it quickly builds a field description by progressively increasing the number of modes and thus the accuracy of the field reconstruction. The results of field reconstruction using the GSA-MD are shown to be in excellent agreement with experimental measurements from two different high peak power laser facilities.
Tuberculosis detection using a low-loss and highly sensitive photonic crystal fiber technique in the terahertz regime
Authors: Taya Sofyan A. , Alhamss Dana N. , Almawgani Abdulkarem H. M. , Alzahrani Ahmad , Colak Ilhami , Patel Shobhit K.
Published: August 2023

This research paper introduces a design and numerical investigation of a photonic crystal fiber (PCF) sensor with a hollow core. The sensor is specifically designed to detect Mycobacterium tuberculosis in the frequency range of 1–2 THz. The cladding region of the PCF sensor incorporates six rectangular air holes and an absorbing layer known as the perfectly matched layer (PML), which is utilized to examine various optical properties. Through a thorough investigation, our designed PCF sensor demonstrates enhanced sensitivity of 98.692%, 98.721%, 98.75%, and 98.764% for four different infected samples of tuberculosis at a frequency of 1.6 THz. The sensor exhibits minimal confinement loss and effective material loss. Furthermore, the numerical aperture and effective mode index of the proposed sensor are analyzed. An effective area of  346,550, 345,110, 343,710, and 343,020µm2 for the four different infected samples of tuberculosis is obtained. The fabrication methods employed for this sensor are mentioned. Overall, this PCF sensor can be promising for a wide range of chemical, gas, and biosensing applications.
Multifunctional-hierarchical flexibility metasurfaces for multispectral compatible camouflage of microwave, infrared and visible
Authors: Kang Jinfeng , Kang Xuefeng , Liu Siyuan , Jing Huihui , Wang Jiayun , Qu Zeng , Duan Junping , Zhang Binzhen
Published: August 2023

The prevalent use of multispectral detection technology makes single-band camouflage devices ineffective, and the investigation of technology for camouflage that combines multispectral bands becomes urgent. The multifunctional-hierarchical flexibility metasurfaces (MHFM) for multispectral compatible camouflage of microwave, infrared, and visible, is proposed, fabricated, and measured. MHFM is primarily composed of an infrared shielding layer (IRSL), a radar absorbing layer (RAL), and a visible color layer (VCL). Among them, IRSL can block thermal infrared detection, and RAL can efficiently absorb microwave band electromagnetic (EM) waves. The VLC can display black (below 28°C), purple (28°C∼31°C), green (31°C∼33°C), and yellow (above 33°C) at different temperatures to achieve visible camouflage. Simulation results show that MHFM can achieve absorption higher than 90% in the 2.9∼13.9 GHz microwave band. Theoretically, the emissivity of MHFM in the infrared spectral range 3∼14 µm is less than 0.34. In addition, the MHFM consists of high-temperature-resistant materials that can be used normally at temperatures up to 175°C, providing excellent high-temperature stability. The measurement results show that the camouflage performance of the MHFM is in excellent agreement with the proposed theory. This study proposes a new method for multispectral camouflage that has broad engineering applications.
High-speed mid-infrared graphene electro-optical modulator based on suspended germanium slot waveguides
Authors: Li Qiyuan , Xiong Xinzhe , Yan Zhiwei , Cheng Guanglian , Xu Fanglu , Shen Zengfan , Yi Qiyuan , Yu Yu , Shen Li
Published: August 2023

The mid-infrared (MIR) region is attracting increasing interest for on-chip synchronous detection and free-space optical (FSO) communications. For such applications, a high-performance electro-optical modulator is a crucial component. In this regard, we propose and investigate a graphene-based electro-absorption modulator (EAM) and microring modulator (MRM) using the suspended germanium waveguide platform. The modulators are designed for the second atmospheric window (8 to 12 µm). The incorporation of double-layer graphene on the suspended slot waveguide structure allows for the significant enhancement of light-graphene interaction, theoretically achieving a 3-dB bandwidth as high as 78 GHz. The EAM shows a calculated modulation depth of 0.022-0.045 dB/µm for the whole operation wavelength range. The MRM exhibits a calculated extinction ratio as high as 68.9 dB and a modulation efficiency of 0.59 V·cm around 9 µm. These modulators hold promise for constructing high-speed FSO communication and on-chip spectroscopic detection systems in the MIR atmospheric window.
Characteristics of the phonon laser in the active levitated optomechanical system
Authors: Xiao Guangzong , Feng Zijian , He Yutong , Kuang Tengfang , Chen Xinlin , Han Xiang , Xiong Wei , Tan Zhongqi , Luo Hui
Published: August 2023

Phonon lasers, coherent oscillations of phonons, have gradually become one of the emerging frontiers in the last decades, and have promising applications in quantum sensing, information processing, and precise measurement. Recently, phonon lasers based on dissipative coupling have been realized in an active levitated optomechanical (LOM) system for the first time. Here, we further investigated the characteristics of the phonon laser in the system above regarding the oscillator amplitude and the phonon laser linewidth. We established both the experimental system and a physical model of the phonon laser. On the basis of simulations and experiments, the influences of pumping power, numerical aperture, the microsphere’s diameter and refractive index on the performance of the phonon lasers are sufficiently discussed. Our work is of great significance for the high-quality phonon lasers generated by the appropriate parameters, which is the basis for the in-depth research and practical application.
Femtosecond pulse laser-engineered glass flexible structures instrumented with an in-built Bragg grating sensor
Authors: Tunon de Lara Mateo , Amez-Droz Loïc , Chah Karima , Lambert Pierre , Collette Christophe , Caucheteur Christophe
Published: August 2023

The advent of near-infrared femtosecond pulse laser has enabled the highly-resolved manufacturing of micro/nano structures in various materials including glass. In this paper, we make use of an automated femtosecond laser system, so-called Femtoprint, to design a monolithic self-instrumented mechanism that we use for in-built strain sensing. To that aim, a flexible structure is designed and produced from a silica planar substrate. It has a flexural joint in which an optical waveguide and a Bragg grating have been directly inscribed using femtosecond pulse laser. The latter provides a non-destructive and non-intrusive measurement tool. The axial strain sensitivity of the in-built Bragg grating has been experimentally determined to be 1.22 pm/μϵ, while its temperature sensitivity is 10.51 pm/°C. The demonstration of such instrumented glass flexible mechanisms paves the way towards a new class of highly integrated sensors suitable for applications at the microscale or in harsh environments.
High-efficiency non-ablative UV laser nano-scale processing of fused silica by stable filamentation
Authors: Hermann Benedikt , Bernard Olivier , Muscarella Luca , Bellouard Yves
Published: August 2023

Over the last decades, three-dimensional micro-manufacturing of fused silica via near-infrared ultrafast laser exposure combined with an etching step has become an established technique for producing complex three-dimensional components. Here, we explore the effect of ultraviolet exposure on process efficiency. Specifically, we demonstrate that shorter wavelengths not only enable enhanced resolution but also yield higher etching selectivity, with an order of magnitude lower pulse energy and significantly higher repetition rates than current practice. This result is obtained using an exposure regime where the laser beam alternates between regimes of self-focusing and defocusing in a stable manner, forming a localized filament. Using this principle, we demonstrate the fabrication of self-organized nano-channels with diameters as small as 120 nm after etching, reaching extreme aspect ratios, exceeding 1500.
Active polarization-converting metasurface with electrically controlled magnitude amplification
Authors: Yang Jie , Yang Weixu , Qu Kai , Zhao Junming , Jiang Tian , Chen Ke , Feng Yijun
Published: August 2023

Recently, reconfigurable polarization-manipulation metasurfaces controlled with active components have gained widespread interest due to their adaptability, compact configuration, and low cost. However, due to the inherent non-negligible ohmic loss, the output energy of these tunable metasurfaces is typically diminished, particularly in the microwave region. To surmount the loss problem, herein, we propose an active polarization-converting metasurface with non-reciprocal polarization responses that is integrated with amplifying transistors. In addition, we provide a design strategy for a polarizer that is insensitive to polarization and has energy amplification capabilities. Experiments are conducted in the microwave region, and amplification of the polarization-converting behaviors is observed around 3.95 GHz. The proposed metasurface is prospective for applications in future wireless communication systems, such as spatial isolation, signal enhancement, and electromagnetic environment shaping.
Influence of electron donor and acceptor substituents on tuning the nonlinear optical properties of zinc phthalocyanine derivatives
Authors: Gao Lijun , Yi Haoyue , Li Biyu , Ren Haoyuan , Zhou Liming , Qu Xiongwei , Fang Shaoming
Published: August 2023

Four phthalocyanine derivatives with different electron donor and acceptor substituents (B1, B2, B3, and B4) were synthesized by a solid-phase melting method. The influence of substituent type on the nonlinear optical properties of the materials was investigated in detail. In the case of similar conjugated structures, B3, which has amino electron-donor groups, presents high intramolecular charge transfer, a low energy gap (2.05 eV), and good nonlinear optical properties. Compared with B3, B4 has a larger π-conjugated structure and its energy gap is 0.04 eV smaller. Moreover, B4 has stronger reverse saturation absorption (7 × 10−12 m/W) and optical limiting performance. The four phthalocyanine derivatives exhibit third harmonic generation (THG) characteristics. Furthermore, the third harmonic strengths of B1, B2, B3, and B4 are 4 times, 9 times, 11 times, and 21 times that of SiO2, respectively. So, B4 has the best application potential in laser protection and frequency conversion.
Imaging human macular pigments with visible light optical coherence tomography and superluminescent diodes
Authors: Gupta Alok K. , Meng Ruoyu , Modi Yasha S. , Srinivasan Vivek J.
Published: August 2023

We demonstrate superluminescent diodes (SLDs) for visible light optical coherence tomography (OCT) of the human retina. SLDs are less costly than supercontinuum sources and have lower intrinsic excess noise, enabling imaging closer to the shot noise limit. While single SLDs are not broadband, they provide power concentrated at specific wavelengths relevant to retinal function. As a new, to the best of our knowledge, application, we image human macular pigments (MPs), which are thought to both aid vision and protect against advanced age-related macular degeneration. Using the unique depth-resolved capabilities of OCT, we localize MPs in depth to Henle’s fibers beneath the foveal pit in the living human retina. Our approach reduces the cost of visible light OCT to nearly that of near-infrared (NIR) OCT while also providing information about clinically relevant MPs which cannot be measured in the NIR.
Inverse design of a polarization demultiplexer for on-chip path-entangled photon-pair sources based on single quantum dots
Authors: Melo Emerson G. , Eshbaugh William , Flagg Edward B. , Davanco Marcelo
Published: August 2023

Epitaxial quantum dots can emit polarization-entangled photon pairs. If orthogonal polarizations are coupled to independent paths, then the photons will be path-entangled. Through inverse design with adjoint method optimization, we design a quantum dot polarization demultiplexer, a nanophotonic geometry that efficiently couples orthogonally polarized transition dipole moments of a single quantum dot to two independent waveguides. We predict 95% coupling efficiency, cross talk less than 0.1%, and Purcell radiative rate enhancement factors over 11.5 for both dipoles, with sensitivity to dipole misalignment and orientation comparable to that of conventional nanophotonic geometries. We anticipate our design will be valuable for the implementation of triggered, high-rate sources of path-entangled photon-pairs on chip.
Three octave visible to mid-infrared supercontinuum generation seeded by multimode silica fiber pumped at 1064 nm
Authors: Leventoux Y. , Granger G. , Arosa Y. , Tilouine I. , Krupa K. , Tonello A. , Couderc V. , Février S.
Published: August 2023

Hyperspectral spectroscopy requires light sources with wide spectral ranges from the visible to the mid-infrared. Here, we demonstrate the first fiber-based mid-infrared supercontinuum covering three octaves of frequency by leveraging 1-µm laser technology. The process consists in spectral broadening of a 1064-nm pump toward 0.48–2.5 µm in a graded-index multimode fiber, followed by a fluoro-indate fiber used to reach deeper into the near infrared (4.3 µm). Finally, an arsenic selenide chalcogenide fiber allows us to reach the 6-µm wavelength region, providing a 0.75–6-µm supercontinuum. We illustrate the potential of this light source by recording mid-infrared absorption spectra of organic compounds.
High focusing efficiency metalens with large numerical aperture at terahertz frequency
Authors: Yang Mengyu , Shen Xin , Li Ziping , Wen Zhongquan , Chen Gang , Zhang Zhihai , Liang Gaofeng , Li Hua , Shang Zhengguo
Published: August 2023

Metalenses have been widely investigated for their features of high design freedom. For practical applications, it is necessary to maximize the efficiency of the metalens. However, it is a great challenge to realize both a high numerical aperture (NA) and high-efficiency metalens in the community. Here, we introduce a method to design a hybrid metalens with a large numerical aperture and high focusing efficiency at terahertz frequency. The hybrid metalens consists of gradient metasurfaces in the central area and metagrating in the peripheral area to achieve high-efficiency beam focusing. To verify this concept, a hybrid metalens with a numerical aperture of 0.95 was designed at λ = 118.8 μm. The simulation results demonstrate that the focusing efficiency of the hybrid metalens is 65.8%. The experimental results show that the designed metalens is able to increase the focusing efficiency from 22.8% to 41.7%. The full widths at half maxima (FWHMs) of the focused spots of the hybrid metalens in the x direction and y direction are 0.72λ and 0.45λ, respectively. The proposed high-efficiency hybrid metalens has promising application prospects in various applications of a complex optical system.
Highly transient stimulated Raman scattering in SrMoO4 under ultrafast laser pumping with a controllable chirp
Authors: Papashvili Alexander G. , Kochukov Yury A. , Tereshchenko Dmitry P. , Smetanin Sergei N. , Kharitonova Polina D. , Shukshin Vladislav E. , Dunaeva Elizaveta E. , Voronina Irina S. , Ivleva Lyudmila I.
Published: August 2023

For the first time, to the best of our knowledge, we demonstrate highly transient, multiwavelength, single-pass Raman generation with combined frequency shifts on two Raman modes of an SrMoO4 crystal with high total Raman conversion efficiency of up to 48% in conditions of competition with self-phase modulation (SPM). A 58-mm-long SrMoO4 crystal was used as the active medium under pumping by the 1030-nm, 40-µJ laser pulses with controllable dispersive stretching in a range of 0.25–6 ps at negative and positive chirping. The pump pulse chirping was optimized for both high- and low-frequency Raman shifts on the primary (888 cm−1) and secondary (327 cm−1) Raman modes of the crystal. At the optimal conditions, four Stokes components of stimulated Raman scattering (SRS) radiation with high- and low-frequency Raman shifts at the wavelengths of 1066, 1134, 1177, and 1261 nm were efficiently generated.
Self-referenced single-shot low-power Stokes polarimetry
Authors: Eshaghi Mahdi , Dogariu Aristide
Published: August 2023

We demonstrate a Stokes polarimeter that not only preserves the power of the light to be analyzed but also requires only a single measurement. The novel design relies on the distinctive characteristics of a corner-cube retroreflector. It is simple and robust, and it circumvents the need for a local oscillator or a controllable reference beam.
Ultra-linear broadband optical frequency sweep for a long-range and centimeter-spatial-resolution OFDR
Authors: Zhong Huajian , Fu Cailing , Li Pengfei , Du Bin , Du Chao , Meng Yanjie , Yin Xiaoyu , Liao Changrui , Wang Yiping
Published: August 2023

We demonstrated a long-range and centimeter-spatial-resolution optical frequency domain reflectometry (OFDR) system based on an ultra-linear broadband optical frequency sweep. The high nonlinear sweeping effect of the distributed feedback (DFB) diode laser was suppressed by a pre-distortion method, ensuring that the injection-locking process remained stable during fast tuning over a large span. An optical linear frequency sweep (LFS) with a sweep range and sweep rate of up to 60 GHz and 15 THz/s, respectively, was ultimately obtained by optimizing the injection-locking system. The high performance OFDR based on the proposed LFS achieved a sampling spatial resolution of 1.71 mm. Furthermore, distributed strain sensing was implemented with high-spatial resolutions of about 5 cm and 7 cm in the measurement range over 1 km and 2 km, respectively.
Spectroscopy and efficient laser performances of a Tm,Ho:CaY0.9Lu0.1AlO4 crystal
Authors: Wang Peifu , Jin Yicheng , Lv Jiawen , Zhang Ning , Xue Mengxin , Li Kuan , Dong Lulu , Liu Junting , Zhao Yongguang , Xu Xiaodong , Liu Shande
Published: August 2023

We report on the spectral properties and laser performances of a novel, to the best of our knowledge, Tm,Ho:CaY0.9Lu0.1AlO4 (Tm,Ho:CYLA) crystal. The polarized absorption spectra, luminescence spectra, and fluorescence lifetime are systematically investigated, presenting a broad and smooth luminescence band. Furthermore, a maximum continuous wave (CW) laser output power of 0.51 W at 2092 nm is obtained under an absorbed pump power of 2.89 W, corresponding to a slope efficiency of 20.4%. The beam quality factors (M2) are measured to be 1.04 in both the x and y axes. A tuning range of 123.4 nm, from 2017.8 nm to 2141.2 nm, is achieved in the CW regime by using a birefringent filter (BF). A stable passively Q switched Tm,Ho:CYLA laser employing Cr2+:ZnSe as a saturable absorber (SA) is realized for the first time, delivering the shortest pulse width of 560 ns with a transmittance of 1%. The results indicate that the Tm,Ho:CYLA crystal is an excellent laser medium for generating high-efficiency laser at ∼2 µm and has a potential in ultrafast laser generation.