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Twisted structures are ubiquitous in plants and animals. Cellulose and chitin are natural polymers that form the structural skeleton of various twisted systems observed across different length scales, ranging from the molecular to the nano, micro, and macro scale. In addition, cellulose and chitin helicoidal structures are found to be responsible for structural coloration, enhanced mechanical properties, and motion. This review first addresses cellulose and chitin‐based chiral molecular systems and nanoscale helicoidal arrangements. Attention is given to cellulose nanocrystals, water interactions, out‐of‐equilibrium structural colorful structures formed by cellulose derivatives, and chitin's optical and mechanical properties. The discussion progresses to the micro and millimeter scales, where specific examples are presented to showcase specialized helical cellulose‐based organizations. The chosen examples illustrate the formation of different helicities, adaptative shapes, and movements at varying length scales, such as in vascular leaf petioles at the micro‐scale and millimeter‐scale in tendrils and awns of Erodium fruits. So far, the results indicate that significant work should be done on out‐of‐equilibrium systems. In addition, much must be learned from nature to produce novel twisted functional materials. This work aims to provide a comprehensive overview of the state‐of‐the‐art study of twisted cellulose and chitin‐based structures and their potential applications. [ABSTRACT FROM AUTHOR]

The article studies a single-type critical Markov branching process with infinite variance of the offspring distribution. The process admits also an immigration component at the time points of a non-homogeneous Poisson process. If additionally the mean number of immigrants is infinite, then proper limit distributions are obtained, under suitable normalization of the sample paths, depending on the rate of change of the intensity of the Poisson process. [ABSTRACT FROM AUTHOR]

The HIV reservoir is a major hurdle for a cure of HIV, but the factors determining its size and dynamics remain unclear. Here the authors show in a large cohort of 610 HIV-1 infected individuals, who are on suppressive ART for a median of 5.4 years, that viral genetic factors contribute substantially to the HIV-1 reservoir size.

Abstract Objectives The aim of the present clinical study was to determine the stability of color and resistance against abrasion and attrition of provisional single implant restorations. Material and Methods A group of 16 patients were treated with provisional crowns made of Telio CAD. Shortly before the insertion the crowns were photographed and scanned using a 3D‐laser scanner. After 8 weeks of clinical usage, the crowns were photographed and scanned again. The vertical occlusal wear and color changes between the restorations were measured. Results The occlusal plane of the original crown showed a statistically significant reduction of 0.052 mm ± 0.037 mm 8 weeks after placement (p

Replicating biological patterns is promising for designing materials with multifaceted properties but replication of twisted cholesteric liquid crystal patterns found in insects is extremely difficult. Here, the authors use liquid crystal oligomers to reproduce the textural, structural and color properties of biological liquid crystals.

Purpose: This study aims to determine the virulence profile of the circulating Bulgarian clinical isolates of GBS including the highly virulent serotype III by molecular methods and evaluate the differences among studied isolates from healthy pregnant women and non-pregnant ill persons. Material and methods: We investigated 104 non-duplicate isolates of GBS obtained from pregnant (n=15) and non-pregnant women (n=89), living in Sofia, Bulgaria. All GBS strains were screened for the presence of important virulence genes, namely bca, cyl(E), rib, hyl(B) and the capsular serotype III detected by Real-time PCR. Results: PCR detection of five important virulence genes showed that cylE (91.3%) was the most prevalent one among the total isolates of GBS. Genes encoding the C protein (bca), hyaluronate lyase (hylB), Alp family protein Rib (rib) were presented in 51%, 17.3% and 22.1% respectively of the examined isolates. By using real-time PCR, we found that 13.5% from all tested Bulgarian GBS strains confirmed as GBS serotype III and harbored cpsI gene. No significant differences between the two groups were observed excluding the presence of cpsI. Conclusion: The risk of neonatal and prenatal GBS infection in 1/3 of healthy pregnant women colonized by streptococcal strains with highly virulent capsular serotype in combination with other strong virulent factors was demonstrated by this study. The regular screening for GBS and properly treatment could be reduce the severe maternal-fetal infections due to this microorganism.

The article presents a developed embedded system for control of electrohydraulic power steering based on multivariable uncertain plant model and advanced control techniques. The plant model is obtained by identification procedure via “black box” system identification and takes into account the deviations of the parameters that characterize the way that the control signal acts on the state of the model. Three types of controller are designed: Linear-Quadratic Gaussian (LQG) controller, H∞ controller and μ-controller. The main result is a performed comparative analysis of time and frequency domain properties of control systems. The results show the better performance of systems based on µ-controllers. Also the robust stability and robust performance are investigated. All three systems achieved robust stability which guarantees their workability, but only the system with µ-controller has robust performance against prescribed uncertainties. The control algorithms are implemented in specialized 32-bit microcontroller. A number of real world experiments have been executed, which confirm the quality of the electrohydraulic power steering control system.

Abstract We compute the NNLO QCD corrections to three-photon production at the LHC. This is the first NNLO QCD calculation for a 2 → 3 process. Our calculation is exact, except for the scale-independent part of the two-loop finite remainder which is included in the leading color approximation. We estimate the size of the missing two-loop corrections and find them to be phenomenologically negligible. We compare our predictions with available 8 TeV measurement from the ATLAS collaboration. We find that the inclusion of the NNLO corrections eliminates the existing significant discrepancy with respect to NLO QCD predictions, paving the way for precision phenomenology in this process.

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. It is also associated with significant concomitant diseases which affect the disease progression course, and contribute to the exacerbation of health status and overall mortality rate. The aim of this study was to identify the most frequent Cardio-vascular disease (CVD) comorbidities among patients with COPD in Bulgaria and their effect on the hospitalization rate, hospital stay duration and health status. A retrospective national observational study was conducted among a statistically representative cohort of 426 patients in Bulgaria. Demographic data, smoking, clinical data for COPD severity and co-morbidity were collected. Health status was assessed through the specific COPD assessment test (CAT). CVD co-morbidity was evaluated by type, considering the GOLD guidelines and number. More than 80% of the patients reported two and more CVD co-morbidities and all of them reported more than two exacerbations and more than two hospitalizations over the last year. The most frequently reported CVD co-morbidity was hypertension, which was present in 88% of the men and in 89% of the women. The data showed a positive correlation between the cardiovascular risk and the progression of the disease. Hypertension, ischemic heart disease and heart failure prevailed in the observed population. With the advancement of COPD, the number of CVDs diseases per patient and CAT score, average hospitalization rate and hospital stay increased.

A system for the rapid prototyping of real-time control algorithms for open-circuit variable displacement axial-piston pumps is presented. In order to establish real-time control, and communication and synchronization with the programmable logic controller of an axial piston pump, the custom CAN communication protocol is developed. This protocol is realized as a Simulink® S-function, which is a part of main Simulink® model. This model works in real-time and allows for the implementation of rapid prototyping of various control strategies including advanced algorithms such as H∞ control. The aim of the algorithm is to achieve control system performance in the presence of various load disturbances with an admissible control signal rate and amplitude. In contrast to conventional systems, the developed solution suggests using an embedded approach for the prototyping of various algorithms. The obtained results show the advantages of the designed H∞ controller that ensure the robustness of a closed-loop system in the presence of significant load disturbances. These type of systems with displacement volume regulation are important for industrial hydraulic drive systems with relatively high power.

The purpose was to assess the level of medication adherence (MA) and related factors among individuals with acromegaly. The secondary goal was to assess the quality of life of patients and whether and how it correlates with the level of adherence. A prospective one-year study was conducted among patients with acromegaly diagnosed, treated, and monitored in the reference center for rare endocrine diseases in Bulgaria in 2021. Clinical data, patients reported outcomes, and health economics data were collected to define the predictors of non-adherence to medicines. Medication adherence level was assessed through a free Morisky–Green 4-item questionnaire. A total of 179 patients with acromegaly were observed. Approximately 62% were female, 50% were between 41 and 60 years, and the mean age at diagnosis was 40.4 years. The response rate to the questionnaires was 53% (n = 95; mean age 53.5 years, 73% female and 26% male). Patients with high levels of MA reported higher median values for the 36-Item Short Form Health Survey (SF-36) in comparison with those with low levels: 65.5 vs. 48.5 (p = 0.017). Similar results for EQ-5D-3L (3-level EuroQol 5D version) values and the level of MA were found: 0.656 vs. 0.796 (p = 0.0123). A low level of adherence was revealed in 34.7% of the patients, with no difference among different age groups. A significant positive determinant for adherence was years lived with acromegaly (OR = 5.625, 95% CI 1.7401–18.1832, p = 0.0039), as shorter duration was related to higher odds for high level of adherence. The current study demonstrates the importance of MA assessment for patients with acromegaly in Bulgaria. The medication adherence to the prescribed therapy among the observed group of patients with acromegaly varied as the percentage of adherent patients was around 65%. Still, there are low-adherent patients, and the responsible factors should be further investigated.

Background: Invasive infections caused by methicillin resistant Staphylococcus aureus and coagulase-negative staphylococci (MRSA/MRSCoN) require fast, adequate treatment. The aim of this study was to develop a faster protocol for direct detection of MRSA/MRSCoN in blood cultures and in abscess punctures based on mecA and species specific identification of S. aureus by polymerase-chain reaction (PCR).Materials and methods: We examined 77 growth-positive BACTEC blood cultures and 50 abscess punctures by routine microbiological assay and simultaneous PCR detection of MRSA/MRSCoN. The specificity of the PCR was evaluated by using DNA from another 15 microbial species for negative controls. We determined the minimum inhibitory concentration (MIC) of oxacillin, vancomycin, tigecycline, linezolid, levofloxacin, clindamycin, and erythromycin against the S. aureus isolates using the E-test. Results: In the blood cultures, the two methods detected 39.3% of MRSA, and 93.9% of MRCoNS. In the punctures, the PCR assay identified 20.9% of MRSA and 79.2% of MSSA. In the puncture cases, there were three PCR MRSA positive and culture negative samples. Screening for susceptibility to 14 antimicrobial agents demonstrated significantly higher (p

In recent years, the development of hydraulic variable displacement axial piston machines has been focused in two main directions: improvement of their construction and improvement of their displacement control methods. The goal of both directions is to increase the efficiency of the machines. Increasing their efficiency is key to improving the efficiency of the entire hydraulic system, whether they are used as pumps or hydraulic motors. This motivates the present work, which essentially contains a developed embedded control system designed for a known type of open circuit axial piston pump. The developed solution is implemented on a laboratory test rig. A detailed description of the hydraulic system in the context of pump displacement control is presented, as well as the developed system architecture for its control. The control system is based on a linear-quadratic Gaussian (LQG) controller. The controller is synthesized on the basis of a model obtained by means of identification based on experimental data. The designed controller is validated through experimental studies, enabling the analysis of its performance.