Equivalence Point Research Articles

Blood from septic patients with necrotising soft tissue infection treated with hyperbaric oxygen reveal different gene expression patterns compared to standard treatment

BackgroundSepsis and shock are common complications of necrotising soft tissue infections (NSTI). Sepsis encompasses different endotypes that are associated with specific immune responses. Hyperbaric oxygen (HBO2) treatment activates the cells oxygen sensing mechanisms that are interlinked with inflammatory pathways. We aimed to identify gene expression patterns associated with effects of HBO2 treatment in patients with sepsis caused by NSTI, and to explore sepsis-NSTI profiles that are more receptive to HBO2 treatment.MethodsAn observational cohort study examining 83 NSTI patients treated with HBO2 in the acute phase of NSTI, fourteen of whom had received two sessions of HBO2 (HBOx2 group), and another ten patients (non-HBO group) who had not been exposed to HBO2. Whole blood RNA sequencing and clinical data were collected at baseline and after the intervention, and at equivalent time points in the non-HBO group. Gene expression profiles were analysed using machine learning techniques to identify sepsis endotypes, treatment response endotypes and clinically relevant transcriptomic signatures of response to treatment.ResultsWe identified differences in gene expression profiles at follow-up between HBO2-treated patients and patients not treated with HBO2. Moreover, we identified two patient endotypes before and after treatment that represented an immuno-suppressive and an immune-adaptive endotype respectively, and we characterized the genetic profile of the patients that transition from the immuno-suppressive to the immune-adaptive endotype after treatment. We discovered one gene MTCO2P12 that distinguished individuals who altered their endotype in response to treatment from non-responders.ConclusionThe global gene expression pattern in blood changed in response to HBO2 treatment in a direction associated with clinical biochemistry improvement, and the study provides potential novel biomarkers and pathways for monitoring HBO2 treatment effects and predicting an HBO2 responsive NSTI-sepsis profile.Trial registrationBiological material was collected during the INFECT study, registered at ClinicalTrials.gov (NCT01790698) 04/02/2013.

Sensitivity to Graphotactic Regularities in Elementary School: Development and Contributing Variables.

Graphotactic regularities are statistical regularities governing orthographic systems that children are sensitive to from the start of their literacy learning. The current study observed changes in children's sensitivity to a set of graphotactic patterns across different grades in elementary school and measured the contribution of skills such as expressive spelling, reading fluency, nonverbal reasoning, and receptive vocabulary to children's sensitivity of these graphotactic regularities. One thousand one hundred one French-speaking children in Grades 1-5 completed a writing under a dictation task, a text reading fluency task, and a pseudo-orthographic choice task involving different graphotactic regularities. These regularities fell into two categories: legal versus illegal, which defines the legality of letter strings in French, and frequent versus less frequent, which refers to acceptable letter strings that vary in frequency of occurrence either at the beginning or end of a word. The results of a repeated-measures analysis of variance showed a developmental difference between graphotactic regularity categories. The frequent versus infrequent patterns developed faster than the legal versus illegal patterns until reaching a point of equivalence in Grade 3. At Grades 4 and 5, legal versus illegal graphotactic regularities progressed more quickly while frequent versus less frequent regularities progressed more slowly. Furthermore, generalized linear mixed-model analyses for both types of graphotactic regularities revealed that they were affected by grade, expressive spelling, reading fluency level, and nonverbal reasoning. This study provides evidence of developmental differences in sensitivity to graphotactic regularities according to the type of regularity studied. Reading fluency and expressive spelling skills contribute to graphotactic regularity sensitivity. Higher scores in expressive spelling, reading fluency, nonverbal reasoning, and an older age were related to higher skills in identifying legal versus illegal graphotactic regularities. Such findings can contribute to educational, clinical, and research applications.

Establishment and simulation study of equivalent model for thermal contact resistance in electronic devices

AbstractTo accurately determine thermal contact resistance (TCR) for the thermal design of electronic devices, a simplified simulation method is first proposed for calculating thermal contact resistance. First, an equivalent geometric model is established based on actual rough surfaces Then, finite element methods are employed to calculate the thermal contact resistance. The results demonstrate that the proposed equivalent geometric model, containing contact point information, can accurately predict the thermal contact resistance, which has a deviation of 10% with the experimental data. Furthermore, the results revealed that both the contact pressure and the surface roughness of the materials significantly influenced TCR, through adjusting the gap thickness. As the contact pressure increased from 200 to 1400 kPa, the TCR decreased from to . The decrease became more gradual at high contact pressure, indicating a nonlinear relationship between pressure and TCR. On the other hand, the surface roughness affected TCR primarily through the equivalent contact point height, that is, the gap thickness between two samples. Moreover, temperature affected TCR mainly through radiative heat transfer, which was dependent on material intrinsic properties. The developed simplified calculation method can efficiently simulate TCR for electronic devices, which not only enhanced the understanding of TCR behaviour but also provided a practical tool for optimizing thermal designs in electronic devices.

Masseter muscle thickness before and after the correction of unilateral functional posterior crossbite in growing individuals: a prospective controlled clinical trial.

To evaluate whether unilateral functional posterior crossbite in growing children creates an asymmetry in masseter muscle thickness and whether this asymmetry is normalized after crossbite correction. Two groups of growing individuals were studied prospectively: (i) a treatment group: children with unilateral functional posterior crossbite, undergoing crossbite correction with maxillary expansion; and (ii) a control group: children without transversal malocclusions and orthodontic treatment. The thickness of the masseter muscles was measured bilaterally using ultrasonographic recordings at three time points: pre-treatment (T0); 9 months after (T1); and 30 months after posterior crossbite correction (T2); and at equivalent time points in the control group. Differences within and between the groups were evaluated using paired and unpaired t-tests respectively. It was found that the thickness of the masseter muscles in patients with unilateral functional posterior crossbite was significantly thinner on the crossbite side (P = .013) by 0.5mm. At T1, the masseter muscle of the treated crossbite side was thicker than that of the previous normal side (0.3mm difference; P = .046) while this difference disappeared at T2 (P > .05). The lack of the inclusion of an untreated posterior crossbite group, and the heterogeneity in appliances used are the principal limitations of this study. The masseter muscles in untreated individuals with unilateral functional posterior crossbite are thinner in the crossbite side than in the contralateral non-crossbite side. This muscular asymmetry however is eliminated some time after successful treatment of this malocclusion, possibly due to the bilateral symmetrization of the activity of the elevator masticatory muscles.

50 Years of Antibody Numbering Schemes: A Statistical and Structural Evaluation Reveals Key Differences and Limitations.

The complementarity-determining region (CDR) of antibodies represents the most diverse region both in terms of sequence and structural characteristics, playing the most critical role in antibody recognition and binding for immune responses. Over the past decades, several numbering schemes have been introduced to define CDRs based on sequence. However, the existence of diverse numbering schemes has led to potential confusion, and a comprehensive evaluation of these schemes is lacking. We employ statistical analyses to quantify the diversity of CDRs compared to the framework regions. Comparative analyses across different numbering schemes demonstrate notable variations in CDR definitions. The Kabat and AbM numbering schemes tend to incorporate more conserved residues into their CDR definitions, whereas CDRs defined by the Chothia and IMGT numbering schemes display greater diversity, sometimes missing certain loop residues. Notably, we identify a critical residue, L29, within the kappa light chain CDR1, which appears to act as a pivotal structural point within the loop. In contrast, most numbering schemes designate the topological equivalent point in the lambda light chain as L30, suggesting the need for further refinement in the current numbering schemes. These findings shed light on regional sequence and structural conservation within antibody sequence databases while also highlighting discrepancies stemming from different numbering schemes. These insights yield valuable guidelines for the precise delineation of antibody CDRs and the strategic design of antibody repertoires, with practical implications in developing innovative antibody-based therapeutics and diagnostics.

The redox titration of Fe (II) ions with K2Cr2O7 using a potentiometry method the effect of EDTA and SCN- ligands

Complexometric titration is often used for determining the metal content, either through direct titration or back titration. This study aimed to investigate redox titration between Mohr salt solutions and potassium dichromate in an acidic atmosphere in the pH range 2. The results showed that the reaction proceeded effectively at pH 2, with Mohr's salt solution acting as titrant. Furthermore, experiments were conducted to compare the effectiveness of EDTA ligands and SCN- ligands in improving the sharpness of the Fe2+/ Cr2O72- redox titration curve at pH 2. Results show that EDTA ligands are more effective than SCN- ligands in improving the sharpness of the titration curve. However, it should be noted that the addition of EDTA ligands can shift the equivalent point volume earlier, so adjustments need to be made in redox titration analysis. Research has also shown that adding excess moles of EDTA to total Fe (II) ions can decrease redox potential in Fe2+/ Cr2O72- systems. These results provide additional insight into the use of EDTA ligands in redox titration analysis and their relevance to redox potential changes in the systems studied.

Assessing the effectiveness of bio-based oil in rejuvenating aged asphalt: a comprehensive physical, rheological, chemical, and mechanical examination

The utilization of reclaimed asphalt pavement (RAP) in flexible pavement construction and rehabilitation has gained significant traction, driven by the need to conserve limited natural resources. This study explores the effectiveness of bio-based oils derived from harvested crops as rejuvenators in asphalt mixtures containing 50% RAP. Comprehensive assessments were conducted, including penetration, softening point, viscosity and ductility tests, to determine the optimal rejuvenator dosage. Additionally, evaluations of rolling thin film oven (RTFO) aging, retained penetration and ductility, equivalent softening and breaking points, plasticity temperature range, stiffness modulus, complex modulus, and phase angle were performed. Fourier-transform infrared (FTIR) spectroscopy, Marshall immersion, and moisture susceptibility tests further validated the rejuvenator's efficacy in improving asphalt properties. The incorporation of 1.8% bio-oil significantly reduced the viscosity of the mixtures, enhancing workability. The rejuvenator effectively compensated for the loss of light components in aged binders, restoring the maximum and minimum temperature performance to levels comparable to virgin asphalt (VA). Mechanical testing revealed that bio-oil mitigated the aging effects of RAP asphalt, and the rejuvenated mixtures showed considerable improvements over both VA and non-rejuvenated RAP mixtures, where the rejuvenated specimens achieved 90.8 and 89.4% of retained strength index (RSI) values for 24- and 48-h immersion periods, respectively comparing with 88.9 and 86% post-immersion of VA for similar durations. These findings underscore the potential of bio-oil as a sustainable and eco-friendly solution for rejuvenating aged asphalts, paving the way for more sustainable asphalt production practices.

Clinical characteristics and prognosis of Talaromycosis marneffei associated immune reconstitution inflammatory syndrome in AIDS patients.

Immune reconstitution inflammatory syndrome (IRIS) is an inflammatory reaction that occurs in HIV/AIDS patients after antiretroviral therapy (ART) initiation. Along with immune system recovery, IRIS can overreact to existing infections or latent pathogens, causing symptoms that mimic those infections. Few studies elucidated the clinical features and prognosis of Talaromycosis marneffei (TSM)-associated IRIS in HIV/AIDS patients. The aim of our study was to evaluate the incidence, clinical characteristics, and prognosis of TSM-associated IRIS by retrospectively analyzing the clinical data of HIV/AIDS patients with TSM. A total of 224 HIV/AIDS inpatients with TSM were enrolled, aged between 19 and 81 years. Among them, 86.6% were male and 13.4% were female, of which 24 (10.7%) patients developed IRIS. In IRIS group, the median time from ART initiation to IRIS occurrence was 9.0 days (IQR, 5.0-16.8 days), with 87.5% (21/24) occurring within 2 weeks. Primary clinical manifestations included recurrent fever and exacerbation of pulmonary infection. At the onset of IRIS, 54.2% (13/24) patients were treated with intravenous dexamethasone, and 12.5% (5/24) patients were treated with oral prednisone for 1-3 weeks. No significant differences in baseline characteristics or ART regimens were observed between IRIS and non-IRIS groups; however, patients in IRIS group had higher levels of CRP, CD4+ count, and CD4+/CD8+ ratio than non-IRIS group (equivalent time point: 1-2 weeks after ART initiation) at IRIS onset. The IRIS group exhibited longer hospital stays and higher readmission rates, but equivalent mortality rates compared with non-IRIS group. IRIS is a common complication in HIV/AIDS patients with TSM, often occurring within 2 weeks after ART initiation and exhibiting more pronounced immune reconstitution. The occurrence of IRIS significantly extended the hospitalization duration and increased the rate of readmission but had no influence on the mortality rate.

Global BIM-point cloud registration and association for construction progress monitoring

Traditional manual and semi-automatic approaches rely heavily on surveying control points and manually picking equivalent point pairs, which is time-consuming and labor-intensive. This paper proposes an automatic algorithm for automatic global BIM-point registration and association to support construction progress monitoring. A representation using distance fields is proposed to efficiently integrate BIM in registration tasks. By leveraging a coarse-to-fine strategy, a primitive-level coarse algorithm is developed to achieve rough alignment between BIM and point cloud. This approach is then complemented by a point-level fine registration approach, which enables simultaneous pose refinement and BIM-point association. Extensive experiments are conducted on the data from simulation and real-world construction sites. The results demonstrate the promising registration and association performance of the proposed algorithm.

Aggregation Characteristics of Biobased Anionic Surfactant, Hydroxy Alkane Sulfonate in Aqueous CaCl2 Solutions: Vesicle and Supported Bilayer Formation.

Vesicles are known to spontaneously adsorb onto solid-liquid interfaces and to form supported bilayers in aqueous solution. Cationic surfactants have typically been used to generate supported bilayers because solid surfaces in water are often negatively charged. The present study investigated the aggregation behavior of an anionic surfactant, hydroxy alkane sulfonate having a C18 alkyl chain (C18HAS) in aqueous CaCl2 solutions. These assessments were performed by acquiring data related to equilibrium surface tension, the solubilization of an oil-soluble dye, UV-visible transmittance, pyrene fluorescence and dynamic light scattering together with freeze-fracture transmission electron microscopy observations. The results suggest that C18HAS can form vesicles in aqueous CaCl2 solutions under certain surfactant concentrations. Specifically, this aggregation behavior is greatly affected by C18HAS/CaCl2 molar ratio. At the C18HAS/CaCl2 molar ratio is less than an equivalence point (that is, less than 2:1), phase separation occurs with the formation of a vesicle above solubility limit of the C18HAS Ca salt. On the other hand, in the case that the C18HAS/CaCl2 molar ratio is above an equivalence point (that is, above 2:1), the Na salt of C18HAS forms micelles above the critical micelle concentration (cmc), causing solubilization of vesicles. Analyses by high-speed atomic force microscopy demonstrated that the C18HAS vesicles can spontaneously form a supported bilayer on a negatively charged mica surfaces, similar to the behavior of cationic surfactant vesicles, even though C18HAS is an anionic surfactant. These results suggest that C18HAS could serve as a detergent component but also as a surface modifier when the C18HAS/CaCl2 molar ratio is optimized.

Mixed finite element method for multi-layer elastic contact systems

With the development of multi-layer elastic systems in the field of engineering mechanics, the corresponding variational inequality theory and algorithm design have received more attention and research. In this study, a class of equivalent saddle point problems with interlayer Tresca friction conditions and the mixed finite element method are proposed and analyzed. Then, the convergence of the numerical solution of the mixed finite element method is theoretically proven, and the corresponding algebraic dual algorithm is provided. Finally, through numerical experiments, the mixed finite element method is not only compared with the layer decomposition method, but also its convergence relationship with respect to the spatial discretization parameter H is verified.

Study on the performance of ground melon vine straw fiber modified asphalt

In order to reduce the waste of resources and the pollution of ecological environment caused by the large amount of waste crop straw accumulation or incineration, and to realize the high-value utilization of waste straw resources, this paper adopts the mechanical crushing method, acid and alkali solution treatment method to prepare the groundnut seedling straw fibers, and compares and analyzes the micro-morphology and chemical composition and thermal stability of the groundnut seedling straw fibers prepared by the physical method, the NaOH solution method, and the HCL solution method, through the scanning electron microscope, infrared spectroscope and the thermogravimetric analysis test; secondly, the optimal blending range of the groundnut seedling straw fibers is preferred. Secondly, the optimal dosage range of ground melon vine straw fiber was selected, the preparation process of ground melon vine straw fiber modified asphalt was proposed, five different dosages of ground melon vine straw fiber modified asphalt were prepared, and the basic properties, viscosity and temperature characteristics, and storage stability of ground melon vine straw fiber modified asphalt were analyzed; and then, a dynamic shear rheometer was used. Dynamic Shear Rheometer and Bending Beam Rheometer tests were used to study the high and low temperature rheological properties and resistance to permanent deformation of ground melon vine straw fiber modified asphalt, and the optimal dosage of groundnut seedling straw fibers was determined; finally, through Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy tests, the chemical components of ground melon vine straw fiber modified asphalt were clarified, and the chemical components of ground melon vine straw fiber modified asphalt were revealed to be the most important. The toughening mechanism of ground melon vine straw fiber modified asphalt was revealed. The results showed that the chemical alkali treatment method was the best preparation process for groundnut straw fiber, and the process flow was to use NaOH solution with a mass fraction of 3 % to treat the ground melon vine straw fiber for 50 min at a temperature of 60 °C; compared with the matrix asphalt, the needle penetration and elongation of the ground melon vine straw fiber modified asphalt decreased with the increase of the blending amount, and the softening point, the equivalent softening point, and the temperature sensitivity of the asphalt increased. Sensitivity enhancement, softening point difference in line with the specification requirements, but the ductility in the low dosage improved; with the increase in the dosage of ground melon vine straw fiber, ground melon vine straw fiber modified asphalt rutting factor, creep modulus, 0.4 %–1 % dosage of the creep rate and creep recovery rate increased, while 1.3 %–1.6 % dosage of the creep rate and the amount of unrecoverable creep flexibility decreased The results show that 0.4 %–1.6 % dosage of melaleuca alternifolia straw fiber modified asphalt high temperature performance and resistance to permanent deformation performance, and 0.4 %–1 % dosage of melaleuca alternifolia straw fiber low temperature performance has also been improved, the overall consideration, to determine the optimal dosage of melaleuca alternifolia straw fiber 1 %; melaleuca alternifolia straw fibers (NaOH) and the asphalt combined with the production of new functional groups, and melaleuca alternifolia straw fibers with each other. Lap cross to form a fiber skeleton grid structure, can play a role in the entire material to transfer stress and crack resistance, asphalt to play the role of enhanced toughening effect.

Narrow Range of Coagulation of Ion Associates of Poly(styrene sulfonate) with Alcian Blue Dye.

The ionic association of Alcian Blue dye with poly(styrene sulfonate) in aqueous solutions was studied for analytical purposes. The quadruple-charged cationic dye, Alcian Blue, was found to form colloidal ionic associates with poly(styrene sulfonate) anions. When the amounts of opposite charges are nearly equal, the resulting ionic associates lose solubility and coagulate rapidly. This effect occurs within a narrow range of the ratio of poly(styrene sulfonate) to Alcian Blue. At the point of charge equivalence, the zeta potential of the resulting particles is zero, which facilitates flocculation. The resulting flocs enlarge to approximately 0.05-0.5 mm and precipitate rapidly. FTIR spectroscopy confirms that the precipitate contains both poly(styrene sulfonate) and Alcian Blue dye. Sedimentation kinetics was studied in detail using scanning turbidimetry. Due to the high molar absorbance of the Alcian Blue dye at 600 nm, the point of equimolar charge ratio was precisely determined by spectrophotometry. The complete precipitation of ionic associates occurs when the amount of poly(styrene sulfonate) ranges from 1.4 to 1.55 mmol per 1 g of Alcian Blue dye. Such a narrow coagulation range allows for the use of the studied effect for quantitative analysis. Both Alcian Blue dye and poly(styrene sulfonate) can be quantified if one of their concentrations is known.

Neural Network-Based Aggregated Equivalent Modeling of Distributed Photovoltaic External Characteristics of Faults

Distributed power networks have a large number of photovoltaic power sources. The bidirection of power flow, different transient control strategies, and installation locations make the transient characteristics highly complex and unpredictable. The vast network of the distribution system makes it almost impossible to predict the electrical quantities of each branch. Reasonable aggregation modeling of the distribution network can greatly simplify the network topology, facilitating transient control and the setting of relay protection settings. An aggregated equivalent modeling method based on the LSTM neural network for distributed PV fault external characteristics is proposed. This method equates the complex distribution network to a highly nonlinear but controllable current source. The method can output the I–V curves of equivalent PV system parallel points under any output power and is able to predict the fault characteristics of the equivalent system after a voltage drop at the parallel point. Compared to traditional mechanistic modeling, this method does not require specific modeling of complex physical systems and is able to accurately map the strong nonlinear inputs and outputs of distribution networks. The established LSTM model first uses a one-dimensional convolutional layer for feature extraction of the PV power coefficients (input), and then two hidden layers are utilized to process the sequence data; the vectors are mapped into a sequence of external characteristic curves (output) in a fully connected layer. A typical distribution network is built based on the traditional PV power model, and a large number of different output combinations are selected for simulation to provide an effective training set and validation set data for LSTM model training. By using the training set data, the weights and offset coefficients of each layer of the LSTM are continuously optimized until the model with the smallest overall error is obtained, which is the optimal model. Finally, the optimal model is utilized to establish an equivalent distribution network system, different degrees of voltage drops are set up at the grid-connected points, the fault characteristics are compared with those of the complete model, and the simulation results can prove the reliability and practicality of the proposed method.

Designing a sparse sensor array for sound field reconstruction using compressive-equivalent source method.

The compressive-equivalent source method (C-ESM) can reconstruct the sound field radiated by sparsely distributed sound sources with a reduced number of sensors. To ensure the performance of the C-ESM, the transfer matrix between the sensors and equivalent point sources should exhibit sufficient incoherence. Given that the configuration of the sensor array affects this incoherence condition, concern regarding the sensor array design would arise. To address such concern, this paper proposes a sensor array design approach. The primary objective of this approach is to minimize the mean coherence of the transfer matrix within the developed iterative framework, providing the incoherence condition required by the C-ESM. Subsequently, the designed sensor array is utilized by the C-ESM for the reconstructions. The effectiveness and practicality of the proposed approach are validated through numerical simulations and experiments.

Accuracy evaluation of dental CBCT and scanned model registration method based on pulp horn mapping surface: an in vitro proof-of-concept

Background and aim3D fusion model of cone-beam computed tomography (CBCT) and oral scanned data can be used for the accurate design of root canal access and guide plates in root canal therapy (RCT). However, the pose accuracy of the dental pulp and crown in data registration has not been investigated, which affects the precise implementation of clinical planning goals. We aimed to establish a novel registration method based on pulp horn mapping surface (PHMSR), to evaluate the accuracy of PHMSR versus traditional methods for crown-pulp registration of CBCT and oral scan data.Materials and methodsThis vitro study collected 8 groups of oral scanned and CBCT data in which the left mandibular teeth were not missing, No. 35 and No. 36 teeth were selected as the target teeth. The CBCT and scanned model were processed to generate equivalent point clouds. For the PHMSR method, the similarity between the feature directions of the pulp horn and the surface normal vectors of the crown were used to determine the mapping points in the CBCT point cloud that have a great influence on the pulp pose. The small surface with adjustable parameters is reconstructed near the mapping point of the crown, and the new matching point pairs between the point and the mapping surface are searched. The sparse iterative closest point (ICP) algorithm is used to solve the new matching point pairs. Then, in the C + + programming environment with a point cloud library (PCL), the PHMSR, the traditional sparse ICP, ICP, and coherent point drift (CPD) algorithms are used to register the point clouds under two different initial deviations. The root square mean error (RSME) of the crown, crown-pulp orientation deviation (CPOD), and position deviation (CPPD) were calculated to evaluate the registration accuracy. The significance between the groups was tested by a two-tailed paired t-test (p < 0.05).ResultsThe crown RSME values of the sparse ICP method (0.257), the ICP method (0.217), and the CPD method (0.209) were not significantly different from the PHMSR method (0.250). The CPOD and CPPD values of the sparse ICP method (4.089 and 0.133), the ICP method (1.787 and 0.700), and the CPD method (1.665 and 0.718) than for the PHMSR method, which suggests that the accuracy of crown-pulp registration is higher with the PHMSR method.ConclusionCompared with the traditional method, the PHMSR method has a smaller crown-pulp registration accuracy and a clinically acceptable deviation range, these results support the use of PHMSR method instead of the traditional method for clinical planning of root canal therapy.

Crystalline Radical Anion of a Diboratriazole and Its Conversion to a Neutral Radical Driven by a Carbene.

One-electron reduction of diboratriazole 1 with potassium graphite (KC8) generates the radical anion 1•-•K+, which undergoes a salt (KCl) elimination reaction upon addition of an N-heterocyclic carbene (NHC) to afford the neutral diboratriazole radical 3. An X-ray diffraction analysis, electron paramagnetic resonance spectroscopy, and computational studies revealed that an unpaired electron in radical species 1•-•K+ and 3 is delocalized over the π-system of the B2N3 and carbene rings. Reversible oxidation of 3 gives rise to a diboratriazole cation 4 featuring a 6π aromatic character. Moreover, treating 1•-•K+ with a half equivalent of a bis(NHC) produces a biradical species 5, in which there is little interaction between two radical moieties separated by the bis(NHC) linker, suggesting the dis-biradical property. 5 undergoes stepwise and reversible two-electron oxidation, establishing three formal oxidation states.

Configuration reconstruction and all-joint synchronous measurement based on vision for segmented linkage manipulator of rigid-flexible dual-arm space robot

A rigid-flexible dual-arm space robot offers promising potential for on-orbit operation due to complementary strengths of its rigid and flexible manipulators. The rigid manipulator has the advantage of large payload capacity and high motion accuracy. The segmented linkage flexible manipulator is ideal for maneuvering in narrow, unstructured environments like internal satellite inspections and maintenance, due to its flexibility and slender body. However, there are inevitable tracking errors due to the multiple cable-driven mechanisms in the flexible manipulator. It’s difficult to get the configuration and end pose of flexible manipulator without adding external sensors. To address these issues, this paper presents a method for configuration reconstruction and all-joint synchronous measurement of the flexible manipulator. The flexible manipulator is captured by the stereovision system mounted on the rigid manipulator. The links’ equivalent center points are recognized by central moment method and edge line extraction method based on the natural characteristics. Joint-to-link kinematic model of flexible manipulator is established to measure joint angles and reconstruct configuration. Several simulations and experiments are carried out to validate the proposed method. The experimental results showed links’ average measurement position errors were less than 13 mm and joint angles reconstructed using the proposed method had an error of approximately 0.35°. These results demonstrate the accuracy and robustness of the proposed method.

Poster 218: Localized Acetabular Bone Density Distributions Are Altered in Unilateral Femoral Acetabular Impingement

Objectives: Femoral acetabular impingement (FAI) can lead to bony and cartilage changes at the joint, and it has been suggested that changes in bone mineral density in the acetabulum may correlate with osteoarthritic degeneration of the hip. In this study, we aimed to use opportunistic quantitative computed tomography (QCT) to map density distributions across the acetabular region in patients with unilateral FAI and determine if there were differences between the affected and unaffected side. Furthermore, we assessed if these differences in density distributions were associated with radiographic measures of FAI. Methods: Twenty patients (age 31.9 (SD 9.2), 13 female) who underwent surgery for unilateral FAI and had an associated CT scan of both hips were included in this retrospective study. Both sides of the pelvis were segmented, and 3D models were created. Estimated bone density values were mapped across the bone models via QCT. A thin-spline semi-landmarking approach was used to allow density values at equivalent anatomical points to be compared within patients and across the group. With the contralateral side used as the control, differences in bone density between sides were calculated. A mixed effect linear regression model was used to determine if there were associations between the localized bone density and radiographic measures of Tonnis grade, alpha angle, lateral center edge angle (LCEA), and cross over sign, while controlling for age and sex. To visualize the data, density changes and statistical results were color-mapped to the bone models. Results: Overall, several regions of the acetabulum were found to have increased bone density in the affected side compared to the contralateral (Figure 1). Specifically, the anterior-superior parts of the acetabular rim appeared to be most affected, along with the posterosuperior region (Figure 2). Limited associations were found between localized density and the clinical variables, with the most notable finding being a region of the superior rim that was found to be associated with the alpha angle (Figure 3). Conclusions: FAI leads to distinct patterns of bone density changes around the acetabulum, although there is still variability at the level of the individual patient. It is unclear whether these changes in bone density may be related to the underlying condition, alterations in the patient’s mechanics due to pain, or a combination of these factors. Providing detailed density maps of the bony anatomy may also assist surgical providers in planning interventions. Further research may elucidate the relationship between bone density changes and long-term degeneration of the joint.

CONDUCTOMETRY ANALYSIS – BENEFICIAL METHOD FOR DETERMINING THE CHEMICAL COMPOSITION OF ALKALINE SILICATE SOLUTIONS

The study deals with the methodology for determining the chemical composition of alkaline silicate solutions. Nowadays, the most widely used method in industry is titration, using the color change of an acid-base indicator. This technique is very accurate for the determination of the total alkalinity (i.e., Na2O, K2O, or Li2O). However, a problem arises in the determination of the SiO2 content, since the color change of the methyl red indicator is very slow and therefore the equivalence point is unclear. The main aim of this work is to present the benefits of conductometric titration, where the equivalence point is indicated by a sudden change in the conductivity. The applicability of the method was verified with other analytical techniques, such as ICP-OES and gravimetric analyses. Their results confirmed the values of the obtained silicate module (the molar ratio of SiO2 and alkaline oxide) in the cases of sodium, potassium and lithium water glasses. Based on the obtained results, one can say that conductometry is a very promising method providing an accurate, fast and instrumentally undemanding chemical characterization of alkaline silicate solutions, usable even in a manufacturing process.