Background: Complications are an inevitable part of orthopaedic surgery, and how one defines complications can have an impact on the ability to learn from them. There have been issues with a commonly used classification system first outlined by Clavien and Dindo. Our aim was to evaluate a modification of this classification system developed for use in our department, with our hypothesis being that this could make our audit presentations more efficient. Methods: A modified Clavien–Dindo Classification was prospectively applied to all complications recorded in the orthopaedic departmental audits at our institution for a 12-month period. The audit discussion was recorded and analysed and compared with the complication audits for the preceding 12-month period. Results: We analysed eight audit presentations before and eight audit presentations after the introduction of a modified Clavien–Dindo classification to our orthopaedic complications over a 2-year period. The number of PowerPoint™ slides (103 vs. 84, p = 0.03) and the time spent on each presentation (88 vs. 71 min, p = 0.02) decreased significantly with the introduction of the modified classification. The novel system was found to have high inter-observer reliability. Conclusions: The modified Clavien–Dindo classification system is a reproducible classification system for orthopaedic complications. It made our audit presentations more efficient. Full article

Lymphoedema is a chronic and dynamic condition that requires the investment of time and resources to appropriately manage. It fluctuates in response to illness, activity, and age, as well as in response to environmental conditions. This qualitative study explored the impact of the climate and climatic variations on lymphoedema. Focus groups were completed with patients (n = 12) and therapists (n = 7) to explore, in depth, their experiences of managing lymphoedema throughout the year. The results suggested that heat and humidity definitely alter the severity of lymphoedema, and a range of individual strategies are required in order to control symptoms. Central to effectively managing lymphoedema is the notion that every body is different and every lymphoedema is different, and therefore understanding one’s own body, what it needs, and what resources are available is essential in maintaining lymphoedema in the face of climate change. Full article

Background: Neospora caninum is a protozoan parasite and a main cause of abortions in cattle worldwide. However, its role in abortions and decreased fertility in sheep is not completely understood, especially due to the complex, multifactorial etiology of abortions. This study aimed to perform a longitudinal field study to investigate the epidemiology of neosporosis and its effect on fertility in endemic sheep herds. Methods: Serological (IFAT) and clinical (outcome of pregnancy) data from 153 ewe-lambs was collected in four intensive management farms in Israel during three consecutive pregnancies. Results: The seroprevalence in ewe-lambs at different farms varied between 24% and 93%. The overall seroprevalence increased from 50% in ewe-lambs to 96.6% at the end of the third pregnancy. Horizontal infection was observed in all farms, with seroconversion in 59% of seronegative sheep. Abortion rates were lower (p = 0.004) in seropositive ewes in the first pregnancy and not significantly higher in seropositive sheep in consecutive pregnancies. Seropositivity or seroconversion were not associated with abortions or repeated abortions; however, many aborting ewes were removed from the flock. Conclusions: No direct short- or long-term association was found between Neopsora infection and abortions. The variations between flocks and pregnancies suggest a more complex etiology. Full article

A possible way to improve the structural safety and robustness of precast building structures is to develop effective precast frame systems with layered beams, which combine prefabricated parts with cast-in situ ordinary concrete, high-performance concrete, fiber concrete, or FRP. The paper provides a new type of precast reinforced concrete frame system with layered beams for rapidly erected multi-story buildings resistant to accidental actions. Using a combination of the variational method and two-level design schemes, a simplified analytical model has been developed for structural analysis of the precast reinforced concrete frame system, both for serviceable and ultimate limit states as well as for accidental actions. The proposed model allows for determining shear deformations and the formation and opening of longitudinal cracks in the intermediate contact zone between precast and monolithic parts of reinforced concrete structural elements of the frame, as well as the formation and opening of normal cracks because of the action of axial tensile force or bending moment in these elements. The design model was validated by comparing the calculated and experimental data obtained from testing scaled models of the precast reinforced concrete frame system with layered beams. The paper investigates and thoroughly analyzes the factors affecting the stiffness and bearing capacity of the intermediate contact zone, discusses the criteria for the formation of shear cracks along the contact zone of precast and monolithic concrete, and examines the change in the stiffness and dissipative properties of layered elements at different stages of their static–dynamic loading. The robustness of the experimental models of the structural system was not ensured under the specified load, section dimensions, and reinforcement scheme. Following an accidental action, longitudinal cracks were observed in the contact joint between the monolithic and prefabricated parts in the layered beams. This occurred almost simultaneously with the opening of normal cracks in adjacent sections. A comprehensive analysis of the results indicated a satisfactory degree of agreement between the proposed semi-analytical model and the test data. Full article

Humanitarian crises caused by war, natural disasters, famine, or disease outbreaks are growing globally and are persistent human tragedies threatening human health, safety, and well-being. Digital-platform-based ecosystems’ corporate social responsibility (CSR) activities have become a vital tool to support humans during crises. However, little is known about the impact of the innovative CSR practices of digital-platform-based ecosystems during a crisis. Therefore, this study investigates this crucial question. Building on dynamic capabilities theory and using thematic analysis of 89 news articles and data from website sources and reports relating to Airbnb Inc.’s CSR innovation in the Afghan 2021 and the Russia–Ukraine 2022 humanitarian crises, we find that strategic digital-platform-based ecosystem-driven CSR interventions during crises can be helpful for society and for businesses. The results suggest Airbnb.org leveraged its resources and capabilities to provide innovative, quick, and timely responses to redefine refugee resettlement, promoting a platform to harness community partnerships, creating a robust collaboration model with international non-governmental organizations and non-governmental organizations, and initiating a novel financial inclusion strategy for refugees and displaced persons. This result also implies that CSR technological innovations during s crisis can be theoretically explained and have further significant implications for policymakers, companies, and societal stakeholders. Full article

This study analyzes the advantages and disadvantages of filtering algorithms for dynamic weighing signals. Highway road surface has road surface unevenness and other influencing factors. The body vibration of the vehicle driving process produces a certain amount of interference signals collected by the load cell to form noise signals. In addition, piezoelectric sensors and amplification circuits introduce a large amount of electrical noise. These noise signals are non-smooth, nonlinear, and have other characteristics. We study the filtering effects of moving average (MA), wavelet transform (WT), and variational mode decomposition (VMD) filtering algorithms on axle weight signals and evaluate the performance of the filtering algorithms through the Root Mean Square Error (RMSE), signal-to-noise ratio (SNR), and Normalized Correlation Coefficient (NCC). The comprehensive analysis shows that the variational modal decomposition filtering algorithm is more advantageous for axial weight signal processing. The design of the axle weight signal noise filtering algorithm is of great significance for improving the accuracy of the overall dynamic weighing system of the vehicle. Full article

Potentiometric titration in a fast and simultaneously high-resolution modality was proposed for the identification and quantification of protolytic groups of variable strength at the surface of primary soil particles. The method is implemented by titrimetric data processing as multicomponent spectra (pK_a spectrotitrimetry). Due to the high resolution, the error of acidity-constant assessment (3–5%) is lower, compared to existing approaches; due to the fast titration, the effect of soil hydrolysis is minimized. The soil profiles for acidic Retisols (podzolic soils)—under a spruce crown and in the intercrown space—were studied. These soils, which have similar bulk properties and genesis but developed under different plant covers, were distinguished by pK_a spectral features at 4–5; 5.5–6.5; 6.5–8.5; 7.5–8.5; and 9–10, as well as total group concentrations. Differences in acidic and basic-group distribution (carboxyl groups, amorphous aluminosilicates, carbonate species, amino groups, soluble (poly)phenolic compounds, phospholipids) and Al and Fe complex compounds within the same soil profiles and between two Retisols were found and quantified. The acidity constants and group concentrations found by pK_a spectrotitrimetry were compared with conventional soil-composition indicators (total organic carbon, oxalate-soluble Fe and Al, and phosphorus), using principal component analysis. The main correlations are between the concentrations of oxalate-soluble Al and groups with pK_a values of 5.0–6.5 and 8.5; oxalate-soluble Fe and pK_a values of 9.0–10.0; and P₂O₅ and pK_a values of 4.0–6.0 and 6.5–8.5. The method provides a set of major acidity values without a priori information on a soil sample and can be used for screening and identifying similar soils. Full article

Background and Objectives: Remimazolam, a novel benzodiazepine, is used for procedural sedation and general anesthesia due to its rapid onset and short duration of action. However, remimazolam-induced anaphylaxis (RIA) is a rare but severe complication. This study aimed to analyze RIA characteristics, focusing on cardiovascular collapse, and provide guidelines for safe remimazolam use. Methods: This study conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Research articles retrieved from PubMed on 26 May 2023, using the keywords ‘remimazolam AND anaphylaxis’ were evaluated based on the inclusion criteria of being written in English and aligning with the World Allergy Organization criteria for anaphylaxis, while studies not meeting these criteria were excluded. All published articles up to the search date were included without any date restrictions. The review analyzed factors such as age, sex, type of anesthesia, remimazolam dose (bolus/continuous), allergic symptoms and sign, epinephrine use, serum tryptase levels, and skin prick tests. Results: Among eleven cases, the mean age was 55.6 ± 19.6 years, with 81.8% male. Hypotension (81.8%) was the most common symptom, followed by bradycardia (54.5%) and desaturation (36.4%). Two patients experienced cardiac arrest. Serum tryptase levels confirmed anaphylaxis in ten cases. Epinephrine was the primary treatment, with intravenous doses ranging from 0.1 mg to 0.3 mg. Conclusions: Vigilance is crucial when administering remimazolam, adhering to recommended dosages, and promptly treating RIA with epinephrine. Further research is needed to understand the risk factors and refine the management strategies. Guidelines for safe remimazolam use are proposed. Full article

Background and Objectives: One of the most significant psychiatric problems in women is depression related to the perinatal period. Our study aims to determine the frequency and course of depressive symptomatology in the perinatal period with particular reference to objective rate and outcome of postpartum depression. Materials and Methods: One hundred and eighty-eight pregnant/postnatal women were included in a prospective, longitudinal, observational study during which the depressive symptomatology was estimated at the third trimester of pregnancy, and the first, sixth, and twelfth month‚ postpartum. All participants completed a semi-structured sociodemographic questionnaire constructed for research purposes, the Edinburgh Postnatal Depression Scale, Toronto Alexithymia Scale, Beck Anxiety Inventory, and The Mood Disorder Questionnaire at each time point. Postpartum depression diagnosis was confirmed by a trained and certified psychiatrist with long-standing experience. For a better understanding of the trajectory of depressive symptomatology and genuine postpartum depression, we classified depression into those with new-onset and those left over from the previous observation period. Results: In general, 48.9% of participants in the study were depressed at some point during the investigation. A total of 10.6% of women were depressed in the third trimester. The highest percentage of new-onset depression (25%) was in the first month after giving birth and was maintained for up to six months, after which the appearance was sporadic. Most of the postpartum depression resolved in the period from the first month to the sixth month after childbirth (20.7%). The episodes mainly had characteristics of unipolar depression. Conclusions: Our results imply that a new onset of depression is most intensive during the first six months, and after that, it is sporadic. Further studies are needed to explore whether all depressive symptomatology in the postnatal period is the same, or perhaps postpartum depression, classified in this way, has specific characteristics, etiology, and consequently different treatment and preventive options. Full article

Background and Objective: Although extracorporeal membrane oxygenation (ECMO) is an essential life-saving technique for patients with refractory cardiopulmonary shock, it can be fatal in certain cases. Case Presentation: A 19-year-old girl treated with ECMO presented with acute limb ischemia 2 days after cannula removal. The decannulation was performed percutaneously by an interventional cardiologist, and the vascular surgery department was consulted after the patient developed symptoms. The first suspected diagnosis was thrombosis due to incorrect use of the closure device. However, the artery had ruptured due to the insertion of a catheter with a cannula that was larger than the patient’s artery. Management and Outcome: Fortunately, excessive bleeding due to the size-mismatched cannula was prevented by an unintentional complication of the closing device, which saved the patient’s life. She underwent a right common femoral artery thrombectomy and patch angioplasty. Hospital guidelines have changed regarding the surgical removal of ECMO cannulas. Discussion: This report aims to highlight the importance of two aspects that are critical to a successful outcome: individualized cannula selection followed by precise insertion and removal and postoperative evaluation of a patient’s final status. Full article

Background and Objectives: This study demonstrates the factor structure and reliability of the Croatian version of the TOPICOP (Topical Corticosteroid Phobia) questionnaire, thereby contributing to further validation and standardization of the measurement of topical corticophobia with dermatological patients or their parents, which directly affects patient or parent compliance, as well as the final therapeutic effect. Materials and Methods: The cross-sectional, observational study was conducted at the University Hospital Centre Split, Department of Dermatovenerology. The research involved inviting 120 participants (age 12–68) who attended the University Hospital Centre Split’s Atopy School, patients examined in the Dermatology Outpatient Clinic of the University Hospital Centre Split and diagnosed with atopic dermatitis (AD) or allergic contact dermatitis (ACD), and parents or legal representatives of patients younger than 12 years old. The TOPICOP questionnaire consists of 12 items assessing the three different components of topical corticophobia (worries, beliefs, and behaviour). Respondents evaluated their perception of the correctness of each statement within 10 min of filling out the questionnaire on a four-point Likert scale. Results: The response rate was 94%, resulting in a sample of 113 respondents (109 adults and 4 children). Factor analysis yielded one common factor of relatively high reliability (Cronbach α = 0.85, 95% CI 0.81 to 0.89). No differences were found in questionnaire scores between male and female participants, nor between the parents/legal representatives of dermatological patients and other patients. Conclusions: This research contributes to further development of the appropriate measuring instrument, its practical application, and thus, the better recognition, resolution, and prevention of topical corticophobia as part of the better overall healthcare and treatment of chronic dermatological patients. Full article

Numerous studies in management and leadership indicate that one’s decision-making style is reflective of one’s leadership style. In the context of civil protection and the fire service, the ability of the fire officers to adopt the best style of decision-making and leadership in each situation represents a critical factor of success. Therefore, the present study was designed to examine the relationship between decision-making and the leadership style of fire officers. For this study, a quantitative method was used, with the application of questionnaires with closed questions. A sample of 346 officers of Portuguese fire stations answered the questionnaire. Correlations between styles are consistent with findings from other studies. Decision-making styles directly influence the leadership styles adopted. Fire officers prioritize people and social concerns, involving teams in decision-making. Research shows positive correlations between participants’ roles, conceptual decision-making, and relation-focused leadership. Higher academic degrees are associated with relationship-focused leadership. Behavioral decision-making mediates the impact of education on leadership styles. Full article

The epidemic norovirus causes vomiting and diarrhea and is a highly contagious infection. The disease is affecting human lives in terms of deaths and medical expenses. This study examines the governing dynamics of norovirus by incorporating Lévy noise into a stochastic $SIRWF$ (susceptible, infected, recovered, water contamination, and food contamination) model. The existence of a non-negative solution and its uniqueness are proved after model formulation. Subsequently, the threshold parameter is calculated, and this number is used to explore the conditions under which disease tends to exist in the population. Likewise, additional conditions are derived that ensure the elimination of the disease from the community. It is proved that the norovirus is extinct whenever the threshold parameter is less than one and it persists for ${\mathbb{R}}_s>1$ . The work assumes two working examples to numerically explain the theoretical findings. Simulations of the study are visually presented, and comparisons are made. The results of this study suggest a robust approach for handling complex biological and epidemic phenomena. Full article

Considering the weak resistance to interference and generalization ability of traditional UAV visual landing navigation algorithms, this paper proposes a deep-learning-based approach for airport runway line detection and fusion of visual information with IMU for localization. Firstly, a coarse positioning algorithm based on YOLOX is designed for airport runway localization. To meet the requirements of model accuracy and inference speed for the landing guidance system, regression loss functions, probability prediction loss functions, activation functions, and feature extraction networks are designed. Secondly, a deep-learning-based runway line detection algorithm including feature extraction, classification prediction and segmentation networks is designed. To create an effective detection network, we propose efficient loss function and network evaluation methods Finally, a visual/inertial navigation system is established based on constant deformation for visual localization. The relative positioning results are fused and optimized with Kalman filter algorithms. Simulation and flight experiments demonstrate that the proposed algorithm exhibits significant advantages in terms of localization accuracy, real-time performance, and generalization ability, and can provide accurate positioning information during UAV landing processes. Full article

The achievement of full autonomy in Unmanned Aerial Vehicles (UAVs) is significantly dependent on effective motion planning. Specifically, it is crucial to plan collision-free trajectories for smooth transitions from initial to final configurations. However, finding a solution executable by the actual system adds complexity: the planned motion must be dynamically feasible. This involves meeting rigorous criteria, including vehicle dynamics, input constraints, and state constraints. This work addresses optimal kinodynamic motion planning for UAVs in the presence of obstacles by employing a hybrid technique instead of conventional search-based or direct trajectory optimization approaches. This technique involves precomputing a library of motion primitives by solving several Two-Point-Boundary-Value Problems (TPBVP) offline. This library is then repeatedly used online within a graph-search framework. Moreover, to make the method computationally tractable, continuity between consecutive motion primitives is enforced only on a subset of the state variables. This approach is compared with a state-of-the-art quadrotor-tailored search-based approach, which generates motion primitives online through control input discretization and forward propagation of the dynamic equations of a simplified model. The effectiveness of both methods is assessed through simulations and real-world experiments, demonstrating their ability to generate resolution-complete, resolution-optimal, collision-free, and dynamically feasible trajectories. Finally, a comparative analysis highlights the advantages, disadvantages, and optimal usage scenarios for each approach. Full article

Cochlear implantation is the therapy used for patients with severe to profound sensorineural hearing loss. For the success of the surgery, it is important that each surgical step is performed with meticulous precision, starting from the correct patient position on the operating table. In elderly or obese patients, this can be difficult to achieve due to cervical rigidity. With this technical note, we want to describe a new position from orthopedic surgery to perform a posterior tympanotomy accurately, ensuring a safe procedure and avoiding unpleasant complications. Full article

A comprehensive analytical method based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous detection of 12 mushroom toxins (ibotenic acid, muscimol, muscarine, β-amanitin, α-amanitin, desoxoviroidin, γ-amanitin, phallisacin, illudin S, phallacidin, phalloidin and illudin M) in mushrooms, serum, urine and simulated gastric fluid. The samples were extracted with water or acetonitrile solution, and the serum sample was further purified with PSA sorbent. Chromatographic separation was performed on an ACQUITY UPLC HSS T3 column with gradient elution using methanol and water containing 1 mM ammonia fluoride as a mobile phase. Mass spectrometric acquisition was performed in electrospray positive ionization mode. Good linearities (R² > 0.994) were obtained for 12 toxins over the range of 0.05~200 µg/L. Matrix-matched calibration curves were used for quantification. The method limits of quantification were 0.01~0.2 mg/kg for mushrooms and 0.15~2.0 µg/L for three biological liquid samples. The mean recoveries of 12 target toxins (spiked at three concentration levels) ranged from 73.0% to 110.3%, with relative standard deviations not exceeding 19.4%, which meets the requirements for the determination of trace compounds in a biological matrix. This method was applied to the analysis of mushroom samples from Yunnan Province. As a result, 11 toxins, not including illudin M, were detected with a concentration range of 0.61~2143 mg/kg. Full article

This study aims to examine the particle number (PN) emissions of a retrofitted heavy-duty spark ignition (HD-SI) engine powered by liquefied petroleum gas (LPG) under both steady-state and transient conditions. The engine was tested under seven steady-state operating points to investigate the PN behavior and particle size distribution (PSD) upstream and downstream of the three-way catalyst (TWC). This analysis intends to assess the impact of including particles with diameters ranging from 10 nm to 23 nm on the total particle count, a consideration for future regulations. The study employed the World Harmonized Transient Cycle (WHTC) for transient conditions to encompass the same engine working region as is used in the steady-state analysis. A Dekati FPS-4000 diluted the exhaust sample to measure the PSD and PN for particle diameters between 5.6 nm and 560 nm using the TSI-Engine Exhaust Particle Sizer (EEPS) 3090. The findings indicate that PN levels tend to increase downstream of the TWC under steady-state conditions in operating points with low exhaust gas temperatures and flows (equal to or less than 500 °C and 120 kg/h). Furthermore, the inclusion of particles with diameters between 10 nm and 23 nm leads to an increase in PN emissions by 17.70% to 40.84% under steady conditions and by an average of 40.06% under transient conditions, compared to measurements that only consider particles larger than 23 nm. Notably, in transient conditions, most PN emissions occur during the final 600 s of the cycle, linked to the most intense phase of the WHTC. Full article

In the preceding decades, rapid technological advancements and increasing democratisation of historical records have been coupled with scientific data from DNA testing, which has revolutionised the family history industry. Going beyond the traditional archives and databases, DNA profiles present nuanced confirmations, puzzles, and contradictions generated through this biological lens. Family history researchers seek iterative engagements with their familial pasts and, in the process, amplify their contemporary identities. This specialised group of historians illuminates their families’ travels through the broader historical landscape, constructing micro-narratives using a broad range of investigative modalities. This article reports on the findings of a large international study (n = 1016) that investigated family history researchers’ motivations for undertaking DNA testing, their experiences, and its impact on their perceptions of individual, national, and global identities using Berzonsky’s socio-cultural model of identity construction (2003, 2011) as an analytic frame. Using a survey methodology, it was concluded that DNA testing can expand and disrupt long-held notions of identity and has the power to shift perceptions and understandings of the self while simultaneously providing a new era of opportunity to reconceptualise national and international affiliations. It suggests further investigative avenues to assess the potential of DNA testing, which may promote social cohesion, inclusiveness, and global citizenship. Full article

Potassium is an essential mineral nutrient for citrus growth and stress response. In this study, the HAK/KUP/KT gene family was identified from the genome of trifoliate orange (Poncirus trifoliata). The physical and chemical properties, chromosomal location, gene structure, evolutionary relationship, conserved motifs, and tissue expression characteristics were analyzed. The expression characteristics under low potassium and salt stress were analyzed by fluorescence quantitative PCR. The function of PtKUP10 was investigated by heterologous expression in Arabidopsis thaliana. The results showed that at least 18 PtKUPs were distributed in seven chromosomes. Phylogenetic analysis showed that four PtKUPs clustered in clade I, which mediated the high-affinity potassium absorption. Gene expression analysis showed that four PtKUPs were highly expressed in root, seven PtKUPs were up-regulated by low potassium stress, and nine PtKUPs were up-regulated by salt stress. The cis-acting elements on the promoter of PtKUPs were predominantly involved in stress and hormone responses. Overexpression of PtKUP10 in Arabidopsis thaliana could enhance salt tolerance by accumulating more potassium in the shoot and reducing sodium content in the shoots and roots. These results indicated that PtKUPs play important roles in potassium absorption and salt stress response, and PtKUP10 might enhance salt tolerance by maintaining potassium and sodium homeostasis. Full article

Oligosaccharides, as a wide type of polysaccharide, have a broad antimicrobial spectrum and promote development as plant growth stimulants. To investigate the regulation effects of different oligosaccharides on the dynamic changes of chlorophyll content, leaf fluorescence, root activity and morphology, and chloroplast ultrastructure, as well as the yields and yield components of strawberry and cucumber, typical greenhouse experiments were conducted over two years (2021–2022). The experimental plants were foliar sprayed with tap water (CK), chitosan oligosaccharide (CSOS), and mixed oligosaccharides (MixOS) five times before flowering. The conventional management (CM) was conducted as a conventional control. The findings of the present study suggest that the application of MixOS has the greatest regulation effects on delayed leaf senescence, well-developed roots, and higher fruit productions of strawberry and cucumber. Exogenous MixOS resulted in significant increases in SPAD values, maximum photochemical efficiency (Fv/Fm), and photochemical quenching coefficiency (qP); they were increased by 1.94–28.96%, 5.41–33.89%, and 9.93–62.07%, compared to the CSOS, CM, and CK treatments, respectively. The orderly and steady structure of thylakoids in the chloroplast, and the randomly distributed starch grains, could be clearly observed in the MixOS treatment, while the non-photochemical quenching (NPQ) was correspondingly reduced by 19.04–45.92%. Meanwhile, the remarkable promotion of root activity and root surface morphology indicators (i.e., root length, surface area, average diameter, and volume) could be observed when exposed to the MixOS treatments, and the total yields of strawberry and cucumber were all increased by 12.40–25.57%. These findings suggest that the mixed oligosaccharides mainly promote the coordinated growth of root and shoot, which leads to the improved yields of strawberry and cucumber. Full article

Acetohydroxyacid synthase (AHAS) is a key enzyme in the first step of the branched-chain amino acid synthesis pathway, and the production of acetohydroxybutyrate from one molecule of 2-ketobutyric acid and one molecule of pyruvate. AHAS is inhibited by feedback from L-valine, L-leucine, and L-isoleucine, and the expression of ilvBN, the gene encoding AHAS, is regulated by all three branched-chain amino acids. A change in amino acids 20–22 on the regulatory subunit (M13 mutation) removes the feedback inhibition by valine. We cloned the gene encoding AHAS (ilvBN) into a vector and then transfected it into Escherichia coli BL21 for expression with targeted changes in amino acids 20–22 on the regulatory subunit, and then determined the activity of the mutated AHAS and its inhibitory effects on valine, isoleucine, and leucine. The enzyme containing the M13 mutation was feedback resistant to all three amino acids. Previous studies have suggested that the binding sites for the three branched-chain amino acids may be at the same variable center. We investigated the enzymatic properties of wild-type and mutant AHAS, modeled their crystal structures, and resolved the mechanism of feedback inhibition induced by mutant M13, which will be useful for continuing the modification of AHAS and the design of broad-spectrum herbicides. Full article