Niu Haijun

Beihang University (BUAA) | BUAA · Department of Biological Science and Technology

Extracorporeal shock wave therapy (ESWT) achieves its therapeutic purpose mainly through the biological effects produced by the interaction of shock waves with tissues, and the accurate measurement and calculation of the mechanical parameters of shock waves in tissues are of great significance in formulating the therapeutic strategy and evaluating...

The network nature of the brain is gradually becoming a consensus in the neuroscience field. A set of highly connected regions in the brain network called “rich‐club” are crucial high efficiency communication hubs in the brain. The abnormal rich‐club organization can reflect underlying abnormal brain function and metabolism, which receives increasi...

Zinc-ion batteries (ZIBs) have an investment in organic cathode materials because of their structural diversities and desirable specific capacities. Low real capacity and poor cycling stability, however, can result from...

Abstract Background It is unclear whether dobutamine, commonly used clinically in echocardiography and short-term congestive heart failure treatment for promoting increased myocardial contractility, affects brain microcirculatory behavior. Cerebral microcirculation plays an important role in ensuring adequate oxygen transport. Therefore, we investi...

Background and objective: Cerebral blood flow (CBF), or perfusion, is a prerequisite for maintaining brain metabolism and normal physiological functions. Diagnosing and evaluating cerebral perfusion status is crucial to managing brain disease. However, cerebral perfusion imaging devices are complicated to operate, should be controlled by specializ...

Objective: To create a comprehensive map of strategic lesion network localizations for neurological deficits, and identify prognostic neuroimaging biomarkers to facilitate the early detection of patients with a high risk of poor functional outcomes in acute ischemic stroke (AIS). Methods: In a large-scale multicenter study of 7,807 patients with...

The past decade has witnessed an explosion of textual information in the biomedical field. Biomedical texts provide a basis for healthcare delivery, knowledge discovery, and decision-making. Over the same period, deep learning has achieved remarkable performance in biomedical natural language processing, however, its development has been limited by...

The accurate evaluation of mental workload of operators in human machine systems is of great significance in ensuring the safety of operators and the correct execution of tasks. However, the effectiveness of EEG based cross-task mental workload evaluation are still unsatisfactory because of the different EEG response patterns in different tasks, wh...

In this study, six conjugated oligomers containing D–A structures were synthesized using the Stille coupling reaction and named PHZ1–PHZ6. All the oligomers utilized demonstrated excellent solubilities in common solvents and notable color variations in the domain of electrochromic characteristics. By designing and synthesizing two electron-donating...

Ischemic strokes (IS) and transient ischemic attacks (TIA) account for approximately 80% of all strokes and are leading causes of death worldwide. Assessing the risk of recurrence or functional impairment in IS and TIA patients is essential to both acute phase treatment and secondary prevention. Current risk prediction systems that rely on clinical...

The cartilage endplates (CEPs) on the superior and inferior surfaces of the intervertebral disc (IVD), are the primary nutrient transport pathways between the disc and the vertebral body. Passive diffusion is responsible for transporting small nutrient and metabolite molecules through the avascular CEPs. The baseline solute diffusivities in healthy...

Objective: To investigate the contribution of alterations in brain structure and function to cognitive function and their interactions in individuals with diabetes and patients with type 2 diabetes mellitus (T2DM). Research design and methods: This population-based study included 2,483 participants who underwent structural MRI (n = 569 with norm...

Motor imagery (MI) based Brain-computer interfaces (BCIs) have a wide range of applications in the stroke rehabilitation field. However, due to the low signal-to-noise ratio and high cross-subject variation of the electroencephalogram (EEG) signals generated by motor imagery, the classification performance of the existing methods still needs to be...

Introduction There is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in hea...

Purpose: Ocular blood flow (OBF) is an important risk factor for incidence, prevalence and progression of some ocular disorders. To date, there are very limited therapeutic options to increase OBF. This study investigated the effect of dobutamine on OBF of heathy adults using 3D pseudocontinuous arterial spin labelling (3D-pcASL), and explored the...

Four new multifunctional polymers (P1, P2, P3, and P4) containing EDOT units were synthesized by the Stille coupling reaction. A PL spectrum test found that the introduction of large conjugated groups led to strong fluorescence emission in all polymers. Among the electrochromic and switch properties, these polymer films exhibited reversible color c...

The nondemented old-old over the age of 80 comprise a rapidly increasing population group; they can be regarded as exemplars of successful aging. However, our current understanding of successful aging in advanced age and its neural underpinnings is limited. In this study, we measured the microstructural and network-based topological properties of b...

Background White matter (WM) microstructural abnormalities have been observed in diabetes. However, evidence of prediabetes is currently lacking. This study aims to investigate the WM integrity in prediabetes and diabetes. We also assess the association of WM abnormalities with glucose metabolism status and continuous glucose measures. Methods The...

For the lack of new chemical system, the primary battery can only use metal as negative materials and transition metal oxide as positive materials, resulting in mineral resources and environmental problems. Here, we reported an organic primary battery. The negative electrode was sodium tert-pentoxide and the positive electrode was citric acid, and...

Organic electrode material can be obtained from biomass through green process, so it is a sustainable green electrode material. However, the capacity attenuation problem of organic electrode seriously affects its application in the field of batteries. Desodiation state and sodiation state are the two corresponding states of electrode materials in r...

The accurate evaluation of operators' mental workload in human-machine systems plays an important role in ensuring the correct execution of tasks and the safety of operators. However, the performance of cross-task mental workload evaluation based on physiological metrics remains unsatisfactory. To explore the changes in dynamic functional connectiv...

Based on the performance of improving the stabilities and coloring efficiencies of triphenylamine polymers, this paper separately synthesized different diamines and 3,4‐dimethylthieno[2,3‐b]thiophene‐2,5‐dicarboxylic acid, and the electrochromic functions of the polymer films were studied on indium‐tin oxide glass (ITO) glass. The polymers had a th...

Degeneration and adaptation are two competing sides of the same coin called resilience in the progressive processes of brain aging or diseases. Degeneration accumulates during brain aging and other cerebral activities, causing structural atrophy and dysfunction. At the same time, adaptation allows brain network reorganize to compensate for structur...

Objective: Exploring the effectiveness of using EEG linear and nonlinear features for accessing mental workload in different tasks. Methods: Working memory tasks with different information types and various mental loads were designed based on N-Back paradigm. EEG signals from 18 normal adults were acquired when tasks were being performed. Linear...

Objective: The generation of quantification maps and weighted images in synthetic MRI techniques is based on complex fitting equations. This process requires longer image generation times. The objective of this study is to evaluate the feasibility of deep learning method for fast reconstruction of synthetic MRI. Approach: A total of 44 healthy s...

The Bayesian inference with prior knowledge has been proposed recently to solve the inverse problem in resonant ultrasound spectroscopy. It allows inferring the elastic properties of high damping materials, such as cortical bone with less dependence on the initial guessed values. In this method, the estimation of the stiffness coefficients is expre...

In this research, we investigated the alterations in the directionality and strength of regional interactions within functionally changed brain networks and their relationship to cognitive decline during the aging process in normal elderly individuals. Thirty-seven cognitively normal elderly people received resting-state fMRI scans and cognitive as...

To explore the effectiveness of using Electro- encephalogram (EEG) spectral power and multiscale sample entropy for accessing mental workload in different tasks, working memory tasks with different information types (verbal, object and spatial) and various mental loads were designed based on the N-Back paradigm. Subjective scores, accuracy and resp...

More and more hybrid brain-computer interfaces (BCI) supplement traditional single-modality BCI in practical applications. Combinations based on steady-state visual evoked potential (SSVEP) and electromyography (EMG) are the widely used hybrid BCIs. The EMG of jaw clench is commonly used together with SSVEP. This article explored the interference w...

Purpose For users with severe motor impairments such as high paraplegia, constructing a simplified, practical, and effective brain-computer interface (BCI) system is critical to improve the quality of life and reduce nursing requirements. This is challenging for users who retain only muscle function above the neck. Method In this experiment, both...

Finite element method based resonant ultrasound spectroscopy (FEM-based RUS) allows elasticity measurement for a material with high quality factor (Q) and arbitrary geometry by minimizing the differences between its theoretically calculated resonant frequencies and the corresponding experimentally measured ones. As Q decreases, some experimental fr...

This study aims to investigate how biochemical composition in subchondral bone (SB) relates to the sulfated glycosaminoglycan (sGAG) content of articular cartilage (AC) in the knee joint of guinea pigs from the early to moderate osteoarthritis (OA). Male Dunkin Hartley strain guinea pigs were grouped according to age (1, 3, 6, and 9 months, with 10...

Injuries related with falls are a major health risk for the elderly. Accurate evaluation of the dynamic walking stability of elderly people is the key to fall prevention. A two-dimensional (2-D) model is proposed in this study given that the custom method is mainly focused on the dynamic walking stability along the antero-posterior axis. An inverte...

Combinations of steady-state visual evoked potential (SSVEP) and electromyography (EMG) are one of the most widely used hybrid brain-computer interfaces (BCI). For users who are suffering from severe motor impairments and could only control muscles above their necks, the EMG of jaw clench is commonly used together with SSVEP. Traditional asynchrono...

Viscoelasticity is an essential property of bone related to fragility, which is altered in aging and bone disease. Bone viscoelastic behavior is attributed to several mechanisms involving collagen and mineral properties, porosities, and bone hierarchical tissue organization. We aimed to assess the relationships between cortical bone viscoelastic da...

The relationships between aging and brain morphology have been reported in many previous structural brain studies. However, the trajectories of successful brain aging in the extremely old remain underexplored. In the limited research on the oldest old, covering individuals aged 85 years and older, there are very few studies that have focused on the...

Resonant ultrasound spectroscopy (RUS) is a nondestructive technique, and one of its applications is to determine the elastic constants of a solid by measuring its free-vibration resonant frequencies. For dissipative materials, the vibration spectrum peaks are broad and strongly overlapped, and in some cases, the resonant frequencies extracted by a...

Background and Objective In flicker-based steady-state visual evoked potentials (SSVEP) brain-computer interface (BCI), the system performance decreases due to prolonged repeated visual stimulation. To reduce the performance decrease due to visual fatigue, the zoom motion based steady-state motion visual evoked potentials (SSMVEPs) paradigm had bee...

Fractal geometry provides a method of analysing natural and especially biological morphologies. To investigate the relationship between the complexity measure, which is indexed as fractal dimensionality (FD), and the traditional Euclidean metrics, such as the volume and thickness, of the brain in older age, we analysed 483 MRI scans of 161 communit...

Aging is associated with changes in brain functional patterns as well as cognition. The present research sought to investigate longitudinal changes in whole brain functional connectivity strength (FCS) and cognitive performance scores in very old cognitively unimpaired individuals. We studied 34 cognitively normal elderly individuals at both baseli...

A series of polyimides (PIs) were prepared by polycondensation of a diamine monomer with five anhydrides (1,2,4,5-benzenetetracarboxylic anhydride (BTA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTD), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BTD), 4-[(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)oxy]-1,3-isobenzofurandione (DDII), and 3,3′,...

In this study, electromyogram (EMG) signals associated with occlusal movement were integrated with steady-state visual evoked potentials (SSVEPs) to develop a hybrid brain–computer interface (hBCI)-based smart home control system for individuals with paralysis. The SSVEP paradigm was used to develop a system containing one main interface and five s...

A monomer (E)-4′,4‴-(1,2-diphenylethene-1,2-diyl)bis([1,1′-biphenyl]-4-carbaldehyde) (DDBC) with AIE properties and two novel DDBC-basing polyazomethines (coded as P1 and P2) were prepared. They were gained in short time, low cost and mild reaction conditions by a straightforward synthetic path. Fluorescent testing shows that DDBC owns an intense a...

Resonant ultrasound spectroscopy (RUS) is an experimental measurement method for obtaining elastic constants of an anisotropic material from the free resonant frequencies of a sample. One key step of the method is to adjust elastic constants to minimize the difference between calculated and experimental frequencies. The method has been widely used...

Six novel electrochromic (EC) polymers containing triphenylamine units and benzo[c][1,2,5]thiadiazole (BTD) units, coded as TPABTA, TPABTD, TPABTD-a, TPABTD-b, TPABTD-c and TPABTD-d, were successfully synthesized through polymer condensation reaction and their electrochromic properties were characterized in detail. The films of these polymers exhib...

According to previous studies, many neuroanatomical alterations have been detected in patients with tinnitus. However, the results of these studies have been inconsistent. The objective of this study was to explore the cortical/subcortical morphological neuroimaging biomarkers that may characterize idiopathic tinnitus using machine learning methods...

Here, we synthesized two kinds of novel conjugated block copolymers P1 and P2 by reacting squaric acid and three kinds of homemade diamine monomers. The polymers P1 and P2 can be dissolved in many normal organic solvents and form films by solution-cast method with high mechanical properties. In addition, when the 10% weight loss is selected as a re...

Enhanced external counterpulsation (EECP) is a noninvasive treatment method for coronary artery atherosclerosis that acts on the vascular endothelial cells. The intracoronary hemodynamic parameters that influence long-term treatment effect are the fundamental factors for the inhibition of intimal hyperplasia, which cannot be measured in real time....

Four kinds of main-chain benzoxazine polymers (PBZ) containing triarylamine (TAA) units were synthesized by Mannich reaction and characterized by 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) techniques, etc. Thermal, optical, photophysical and electrochemical properties were studied. The 50% of char residue is left in N2...

Background: Enhanced external counterpulsation (EECP) is an effective method for treating patients with cerebral ischemic stroke, while hemodynamics is the major contributing factor in the treatment of EECP. Different counterpulsation modes have the potential to lead to different acute and long-term hemodynamic changes, resulting in different trea...

Resonant ultrasound spectroscopy (RUS) allows identification of the elastic properties of solid materials vibrating under an ultrasonic excitation from the measurement of their inherent frequencies. Retrieving the resonant frequencies is therefore a key signal processing step in RUS, which is generally addressed using a linear prediction filter. In...

Purpose The application of Chinese Mandarin electrolaryngeal (EL) speech for laryngectomees has been limited by its drawbacks such as single fundamental frequency, mechanical sound, and large radiation noise. To improve the intelligibility of Chinese Mandarin EL speech, a new perspective using the automatic speech recognition (ASR) system was propo...

Mechanical properties is critical for developing dental materials and designing dental prosthesis. The aim of this study is to investigate the mechanical properties of human enamel material based on resonant ultrasound spectroscopy method (RUS). First, some pure enamel specimens were prepared carefully from five fresh human teeth. Under the assumpt...

To assist effective and precise diagnosis for mild cognitive impairment (MCI) and Alzheimer’s disease (AD), Electroencephalograph (EEG) has been widely used in clinical research of patients with AD at MCI state. To study the linear and nonlinear abnormality of EEG in AD and MCI patients, multiple characteristics was applied to distinguish AD and MC...

Background: In steady state visual evoked potential (SSVEP)-based brain-computer interfaces, prolonged repeated flicker stimulation would reduce the system performance. To reduce the visual discomfort and fatigue, while ensuring recognition accuracy, and information transmission rate (ITR), a novel motion paradigm based on the steady-state motion v...

This paper aims to apply the resonant ultrasound spectroscopy technique (RUS) combined with micro computed tomography (μ-CT) and finite element method (FEM) to quantify the elastic constants of the irregular hard biological tissue material such as enamel. In this method, the resonant frequencies of an irregular shaped sample tested under stress-fre...

Here, we synthesized four kinds of monomers of 3,6-dibromo-(N-phenyl)carbazole with different substituent group, DCB, DDC, DNC and DTC, respectively, and used 4-(3-bromo-9H-carbazol-9-yl)benzaldehyde to react with triphenylamine (TPA) unit and hydrazine hydrate unit, respectively, to obtain the other two monomers, BCB-TPA and BCB-HH. Six novel poly...

A series of novel polymers (coded as BCT‐1 to BCT‐6 (BTC is block triphenylamine)) based on N¹‐(4‐aminophenyl)‐N¹‐phenyl benzene‐1,4‐diamine, pyridine‐2,6‐dicarboxylic acid, 4,4′‐(phenyl azanediyl)dibenzoic acid (PDA), and different diamine compounds were synthesized successfully through a polymer condensation reaction. For comparison, model polyme...

Introduction Informant-reported subjective cognitive decline (iSCD) has been associated with a higher risk of conversion to dementia, but the findings of whole brain functional connectivity strength (FCS) changes in iSCD are limited. Methods The sample comprised 39 participants with iSCD and 39 age- and sex- matched healthy controls. The global ab...

Background Falls are one of the major causes of injury in the elderly. Obesity may be related to the risk of falling. Understanding the dynamic stability mechanisms of obese elderly people during gait is important as it may be associated with fall protection. Research question Does obesity affect the dynamic walking stability of elderly people? M...

Objective: To propose a square's ring motion stimulation based on steady-state motion visual evoked potential, and compare it with the commonly used visual stimulation modes (Newton's ring motion, square flicker and circular flicker). Methods: EEG signals were collected while 9 experimental subjects gazing at four stimulation and pattern analyze...

Objectives: To investigate the elastic properties of human enamel using resonant ultrasound spectroscopy (RUS). Methods: Six rectangular parallelepiped specimens were prepared from six human third molars. For all specimens, the theoretical resonant frequencies were calculated using the Rayleigh-Ritz method, knowing the specimen mass density and...

An electrolarynx (EL) is one of the most popular voice rehabilitation technologies used after laryngectomy. However, most ELs generate monotonic EL speech, which has been shown to create a particular deficit in speech intelligibility, especially for Chinese Mandarin (Mandarin). Mandarin is a tonal language that makes lexical distinctions using vari...

The purpose of this study was to investigate age-related changes in the morphological, biochemical and mechanical properties of articular cartilage (AC) and subchondral bone in the rat tibial plateau. Female Wistar rats were grouped according to age (1, 3, 5, 7, 9, 11, 13, 15, 16 and 17 months, with 10 rats in each group). The ultrastructures, surf...

Amnestic MCI (aMCI) and non-amnestic MCI (naMCI) are considered to differ in etiology and outcome. Accurately classifying MCI into meaningful subtypes would enable early intervention with targeted treatment. In this study, we employed structural magnetic resonance imaging (MRI) for MCI subtype classification. This was carried out in a sample of 184...

Herein, three kinds of electrochromic aromatic polyimides (PIs) were synthesized from 4,4′-diamino-4″-(quinolin-8-yloxy) triphenylamine (DAQTPA) with different dianhydrides, respectively. These PIs showed good thermostability below 450 °C even in air atmosphere. The maximum UV–vis absorption bands of PIs located at 321–338 nm for solid films. The h...

The measurement of enamel mechanical properties offers great significance for the design, development and evaluation of clinical dental restorative materials. In this paper, resonant ultrasound spectroscopy (RUS) was proposed to measure the full second-order elastic tensor of human enamel specimens, and the mechanical parameters of human enamel, in...

This paper proposed to take advantages of resonant ultrasound spectroscopy (RUS) to measure the mechanical properties of human dentin specimen. The resonant spectroscopy of the dentin specimen was obtained between the frequency bands 155 and 575 kHz, and resonant frequencies were extracted by linear predictive filter and then by Levenberg-Marquardt...

Tone is important in tonal languages, especially in Mandarin. However, there is presently no commercially available electrolarynx (EL) for laryngectomized Mandarin speakers. Moreover, few studies have focused on this area. Our purpose is to design an EL that produces the four Mandarin tones and to evaluate its performance. We designed a wheel-contr...

Currently, various kinds of electrical stimulation equipment are used in the rehabilitation of muscle function for patients with hemiplegia, but many defects can be found in those designs, for example, insufficient feedback parameter, unsynchronized information, unintuitive display and so on. Therefore, this study introduces an electrical stimulati...

This work describes a teaching reform of Tissue Engineering course that designs a laboratory course for senior undergraduate students, where students are challenged with a real-life tissue engineering application and provided with a hands-on experience applying oriented biomaterial technology and cytotechnology by conducting an experiment. Forty se...

This paper proposed a rehabilitation training system with electromyography (sEMG) feedback for stroke patients based on ARM embedded system and LabVIEW. The system can achieve real-time acquisition, processing and dualview of multi-channel sEMGs and compute related sEMG parameters including iEMG, RMS, MPF and co-contraction ratio. The system was de...

This paper proposed a mobile vital-signs monitoring system based on ZigBee localization and wireless transmission technology for the elderly in nursing home. The system can monitor the vital-signs (pulse, ECG and blood oxygen), localize human body and warn in emergency. The validity and accuracy of this system were testified by the experiments of m...

The objective of this study was to observe the age-related changes of sulfated glycosaminoglycan (sGAG) content and surface roughness of hip joint cartilage of elderly people based on Equilibrium Partitioning of an Ionic Contrast Agent (EPIC) Micro-CT. 35 human hip cartilage-bone samples were prepared from hip-fracture patients whose age were from...

Background and purpose: Automated anatomical labeling (AAL) provides an automatic brain region segmentation method to allow objective measurement of regional brain volume. Nonlinear registration plays a critical role in such automated region-based volumetry. The aim of this study was to compare age-related brain regional volume changes using two n...

Previous neuroimaging studies have suggested that cerebral changes over normal aging are not simply characterized by regional alterations, but rather by the reorganization of cortical connectivity patterns. The investigation of structural covariance networks (SCNs) using voxel-based morphometry is an advanced approach to examining the pattern of co...

This study tried to monitor proteoglycans (PG)-depletion in progressive trypsin digested porcine articular cartilage (AC) samples with a conventional ultrasound system. 10 cartilage-bone samples were prepared from normal porcine femoral condyle cartilages and were digested with 0.25% trypsin solution for two hours. The dynamic process of the PG dig...

Background: Physical loading changes bone microstructure and may influence quantitative ultrasound (QUS) parameters. This in vitro study aims at evaluates the effect of physical loading on bone QUS measurement. Objective: Ten fresh bovine bone specimens were studied. Specimens were scanned by a micro-CT and the density and structure parameters of s...

This study applied a chemical decalcification method to explore the variations of ultrasonic parameters and Young's modulus of the cancellous bone samples at different decalcification stages and the correlations between them. Cancellous bone specimens were obtained from proximal ends of bovine femoral and then resorted to progressively decalcificat...

Osteoporosis is a worldwide health problem with enormous social and economic impact. Quantitative ultrasound (QUS) method provides comprehensive information on bone mass, microstructure and mechanical properties of the bone. And the cheap, safe and portable ultrasound equipment is more suitable for public health monitoring. QUS measurement was norm...

Many studies have shown that strategies of nerve regeneration and cell-based transplantation are valid based on animal models of spinal cord injury (SCI). To apply these strategies and bridge spinal cord defects, the identification and precise localization of lesions during spinal cord surgery is necessary. The aim of the present experiment was to...

The purpose of this study was to explore the triphasic mechanical properties of osteoarthritic cartilage with different pathological grades. First, samples of cartilage from rabbits with different stages of osteoarthritis (OA) were graded. Following this, the cartilage was strained by a swelling experiment, and changes were measured using a high-fr...

The human brain undergoes many age-related changes, such as the atrophy of brain volume, the thinner of cortical thickness, the loose of white matter and so on. Here we aimed to explore whether the covariance existed among the regional gray matter volume with aging. 169 brain magnetic resonance images (MRI) of healthy people (54 males and 115 femal...

Subtle changes of articular cartilage (AC) can lead to tissue degeneration and even osteoarthritis (OA). The early degeneration of AC is closely related to a change in proteoglycans (PG) content. The observation of PG is therefore an appropriate way of studying OA and evaluating the degree of AC degeneration. In this study, 20 cartilage-bone sample...

In this paper we describe a plantar pressure monitoring system which would be applied to monitor the plantar pressure for daily activity exercise stress assessment. The system realized real time parameter measurement, transmission, data analysis and storage. Based on the previous study, 5 force sensors were located on the insole, which could estima...

Mild cognitive impairment (MCI) is an intermediate cognitive state between normal aging and dementia. Previous studies have found the atrophy of the gray matter and white matter in MCI compared to normal aging. However, the relatively few reports focused on the sulcal morphology in MCI subjects. Here, we investigated the changes of sulcal morpholog...

We utilized a sulcus-based computational approach to investigate the relationship between the three-dimensional (3D) morphology of the central sulcus (CS) and age. The anterior and posterior walls of the CS were manually outlined using high-resolution magnetic resonance images of 295 right-handed healthy participants (age range: 18~94years). Surfac...