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Introduction Tigecycline is a potential alternative to trimethoprim–sulfamethoxazole in treating Stenotrophomonas maltophilia infections due to its potent in vitro antimicrobial activity. Clinical evidence regarding the use of tigecycline in the treatment of S. maltophilia infections is scarce. In this study, we assessed the efficacy of tigecycline treating ventilator-associated pneumonia (VAP) due to S. maltophilia in comparison with fluoroquinolones. Methods This is a multicenter retrospective cohort study of patients admitted between January 2017 and December 2020 with the diagnosis of VAP caused by S. maltophilia receiving either tigecycline or fluoroquinolones as the definitive therapy ≥ 48 h. Clinical outcomes including 28-day mortality, clinical cure and microbiological cure were analyzed. Results Of 82 patients with S. maltophilia VAP included, 46 received tigecycline, and 36 received fluoroquinolones; 70.7% of patients had polymicrobial pneumonia, and the appropriate empiric therapy was applied to only 14.6% of patients. The overall 28-day mortality was 39%. Compared with patients receiving fluoroquinolones, tigecycline therapy resulted in worse clinical cure (32.6% vs. 63.9%, p = 0.009) and microbiological cure (28.6% vs. 59.1%, p = 0.045), while there was no statistical difference between 28-day mortality (47.8% vs. 27.8%, p = 0.105) in the two groups. Similar results were also shown in the inverse probability of treatment weighted univariable regression model and multivariable regression model. Conclusions The standard dose of tigecycline therapy was associated with a lower clinical and microbiological cure rate but not associated with an increased 28-day mortality in patients with S. maltophilia VAP compared with fluoroquinolones. Considering the unfavorable clinical outcomes, we therefore recommend against using the standard dose of tigecycline in treating S. maltophilia VAP unless new clinical evidence emerges. Supplementary Information The online version contains supplementary material available at 10.1007/s40121-021-00516-5.

Basalt fibre-reinforced plastic sheet (BFRP) enhancement is one of the strengthening methods suitable for concrete structures due to the low price and high tensile strength of BFRPs. It is of great importance to study the mechanical performance of BFRP-reinforced low-strength concrete structures in freeze–thaw environments. Therefore, 15 concrete beam specimens were designed, and a fast freeze–thaw experiment was conducted in this research to consider different parameters, such as the number of freeze–thaw cycles, sequence of freezing–thawing and BFRP pasting and other factors. The mechanical performance of low-strength concrete beams reinforced with BFRPs under freeze–thaw cycles was investigated. The failure mode and load–deflection curves of specimens were also analysed. The test results revealed that the ultimate strength of concrete beams reinforced with BFRPs was greatly improved, with a maximum increase of 32.7%. With increasing number of freeze–thaw cycles, the ultimate strength of beams gradually decreased over the bearing capacity of non-frozen-thawed concrete beams reinforced with BFRPs (F0b), and the bearing capacity of low-strength concrete beams reinforced with BFRPs decreased 17.1% after 50 continuous freeze–thaw cycles, while the beam failure mode changed from bending failure to shear failure accompanied by de-bonding failure. A mechanical model of BFRP-reinforced low-strength concrete beams was constructed under the de-bonding failure mode, and a calculation equation to determine the magnitude of de-bonding failure was proposed. Finally, finite element analysis of specimens was performed with cohesive elements to simulate the nonlinear softening mechanical behaviour of the BFRP–concrete interface.

Due to the damage of scalp because of chemical dyes, increasing attention had been paid to the ecological dyeing of human hair. To address the need for ecological restoration and dyeing of human hair, herein, a novel approach has been proposed via laccase-mediated in situ oxidation of dihydroxy phenylalanine (dopamine). As laccase can catalyze dopamine oxidation and then polymerization to produce strongly colored polymers, different biological coloration processes of human hair based on this process were investigated: (i) Human hair was treated with laccase alone; (ii) The absorption of human hair with dopamine, followed by further catalysis of air; (iii) The absorption of human hair with dopamine, followed by further catalysis of laccase; (iv) Simultaneous laccase-mediated polymerization and dyeing of human hair; and (v) Polymerization of Dopamine with laccase and then dyeing human hair. The surface properties of dyed hair were evaluated in terms of ultraviolet (UV)-protection, color fastness, Fourier transforming infrared spectrum (FT-IR), optical microscope, and scanning electron microscopy (SEM). The results show that best hair dyeing effect was achieved via simultaneous laccase-mediated polymerization and dyeing. The dyed hair obtained K/S values of 28, light fastness of level 5, and UPF of 100+. The optical microscope and SEM observations show that the surface of colored hair fibers was covered with thin burrs, which can be attributed to polydopamine attached with physical adhesive force and covalent reaction. FT-IR analysis shows that functional groups were present on the surface of the dyed hair which can be considered as introduction of hydroxyl radical groups. This biological stain technique may be widely used in dyeing of hair with black color.

Thermoelastic damping (TED) is one of the main internal energy dissipation mechanisms in micro-/nano-resonators. Accurate evaluation of TED is important in the design of micro-electromechanical systems and nano-electromechanical systems. In this paper, a theoretical analysis on the TED in functionally graded material (FGM) micro-beam resonators is presented. Equations of motion and the heat conduction equation governing the thermodynamic coupling free vibration of non-homogenous micro-beams are established based on the Euler–Bernoulli beam theory associated with the modified couple stress theory. Material properties of the FGM micro-beam are assumed to change in the depth direction as power-law functions. The layer-wise homogenization method is used for solving the heat conduction equation. By using the mathematical similarity of eigenvalue problem between the FGM beam and the reference homogeneous one, the complex natural frequency including TED is expressed in terms of the natural frequency of the isothermal homogenous beam. In the presented numerical results, influences of various characteristic parameters, such as beam thickness, material gradient index, structure size, vibration mode and boundary conditions, on TED are examined in detail. It shows that TED decreases with the increases in the values of length scale parameters because the latter lead to the increase in structural stiffness.

In this paper, correspondence relations between the solutions of the static bending of functionally graded material (FGM) Reddy–Bickford beams (RBBs) and those of the corresponding homogenous Euler–Bernoulli beams are presented. The effective material properties of the FGM beams are assumed to vary continuously in the thickness direction. Governing equations for the titled problem are formulated via the principle of virtual displacements based on the third-order shear deformation beam theory, in which the higher-order shear force and bending moment are included. General solutions of the displacements and the stress resultants of the FGM RBBs are derived analytically in terms of the deflection of the reference homogenous Euler–Bernoulli beam with the same geometry, loadings and end conditions, which realize a classical and homogenized expression of the bending response of the shear deformable non-homogeneous FGM beams. Particular solutions for the FGM RBBs under specified end constraints and load conditions are given to validate the theory and methodology. The key merit of this work is to be capable of obtaining the high-accuracy solutions of thick FGM beams in terms of the classical beam theory solutions without dealing with the solution of the complicated coupling differential equations with boundary conditions of the problem.

Suppose that G is a finite group and H is a subgroup of G. We say that H is a BNA-subgroup of G if either H x = H or x ∈ for all x ∈ G. The BNA-subgroups of G are between normal and abnormal subgroups of G. We obtain some new characterizations for finite groups based on the assumption that all cyclic subgroups are BNA-subgroups.

Keloids are fibroproliferative disorders characterized by the overabundant deposition of extracellular matrix (ECM), especially collagen and overgrowth of scar tissue in response to cutaneous injury. In this study, we isolated a selenium (Se)-containing polysaccharide (Se-ZGTP-I) from Ziyang green tea and explored its potential therapeutic effects on keloid fibroblasts formation. 3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and annexin V/propidium iodide (PI) staining assays demonstrated that Se-ZGTP-I or neuron-glia 2 (NG2) short hairpin RNA (shRNA) significantly inhibited proliferation of human keloid fibroblasts via induction of apoptosis. Besides, the activation of caspase-3 and the subsequent cleavage of poly (ADP-ribose) polymerase (PARP) were observed in keloid fibroblasts following Se-ZGTP-I (200 and 400 μg/ml) or NG2 shRNA treatment. Moreover, Western blotting analysis showed that treatment of keloid fibroblasts with Se-ZGTP-I (200 and 400 μg/ml) or NG2 shRNA resulted in an increase of pro-apoptotic protein Bax expression and a decrease in expression levels of anti-apoptotic protein Bcl-2 and NG2. In addition, type I collagen biosynthesis and protein expression in keloid fibroblasts following TGF-β1 stimulation were decreased by Se-ZGTP-I (200 and 400 μg/ml) or NG2 shRNA management. Current findings imply that Se-ZGTP-I has a therapeutic potential to intervene and prevent keloid formation and other fibrotic diseases.

ClC-3, a member of the ClC chloride (Cl(-)) channel family, has recently been proposed as the primary Cl(-) channel involved in cell volume regulation. Changes in cell volume influence excitability, contraction, migration, pathogen-host interactions, cell proliferation, and cell death processes. In this study, expression and function of ClC-3 channels were investigated during epidermal stem cell (ESC) migration. We observed differential expression of CLC-3 regulates migration of ESCs. Further, whole-cell patch-clamp recordings and image analysis demonstrated ClC-3 expression affected volume-activated Cl(-) current (I Cl,Vol) within ESCs. Live cell imaging systems, designed to observe cellular responses to overexpression and suppression of ClC-3 in real time, indicated ClC-3 may regulate ESC migratory dynamics. We employed IMARIS software to analyze the velocity and distance of ESC migration in vitro to demonstrate the function of ClC-3 channel in ESCs. As our data suggest volume-activated Cl(-) channels play a vital role in migration of ESCs, which contribute to skin repair by migrating from neighboring unwounded epidermis infundibulum, hair follicle or sebaceous glands, ClC-3 may represent a new and valuable target for stem cell therapies.

The relationship between the critical buckling loads of functionally graded material (FGM) Levinson beams (LBs) and those of the corresponding homogeneous Euler-Bernoulli beams (HEBBs) is investigated. Properties of the beam are assumed to vary continuously in the depth direction. The governing equations of the FGM beam are derived based on the Levinson beam theory, in which a quadratic variation of the transverse shear strain through the depth is included. By eliminating the axial displacement as well as the rotational angle in the governing equations, an ordinary differential equation in terms of the deflection of the FGM LBs is derived, the form of which is the same as that of HEBBs except for the definition of the load parameter. By solving the eigenvalue problem of ordinary differential equations under different boundary conditions clamped (C), simply-supported (S), roller (R) and free (F) edges combined, a uniform analytical formulation of buckling loads of FGM LBs with S-S, C-C, C-F, C-R and S-R edges is presented for those of HEBBs with the same boundary conditions. For the C-S beam the above-mentioned equation does not hold. Instead, a transcendental equation is derived to find the critical buckling load for the FGM LB which is similar to that for HEBB with the same ends. The significance of this work lies in that the solution of the critical buckling load of a FGM LB can be reduced to that of the HEBB and calculation of three constants whose values only depend upon the through-the-depth gradient of the material properties and the geometry of the beam. So, a homogeneous and classical expression for the buckling solution of FGM LBs is accomplished.

Background Drought may become one of the greatest challenges for cereal production under future warming scenarios, and its impact on insect pest outbreaks is still controversial. To address this issue, life-history responses of the English grain aphid, Sitobion avenae (Fabricius), from three areas of different drought levels were compared under three water treatments. Results Significant differences were identified in developmental time, fecundity and adult weight among S. avenae clones from moist, semiarid and arid areas under all the three water treatments. Semiarid and arid area clones tended to have higher heritability for test life-history traits than moist area clones. We identified significant selection of water-deficit on the developmental time of 1st instar nymphs and adult weight for both semiarid and arid area clones. The impact of intermediate and severe water-stress on S. avenae’s fitness was neutral and negative (e.g., decreased fecundity and weight), respectively. Compared with arid-area clones, moist- and semiarid-area clones showed higher extents of adaptation to the water-deficit level of their respective source environment. Adult weight was identified as a good indicator for S. avenae’s adaptation potential under different water-stress conditions. After their exposure to intermediate water-deficit stress for only five generations, adult weight and fecundity tended to decrease for moist- and semiarid-area clones, but increase for arid-area clones. Conclusions It is evident from our study that S. avenae clones from moist, semiarid and arid areas have diverged under different water-deficit stress, and such divergence could have a genetic basis. The impact of drought on S. avenae’s fitness showed a water-level dependent pattern. Clones of S. avenae were more likely to become adapted to intermediate water-deficit stress than severe water-deficit stress. After continuous water-deficit stress of only five generations, the adaptation potential of S. avenae tended to decrease for moist and semiarid area clones, but increase for arid area clones. The rapid shift of aphids’ life-history traits and adaptation potential under drought could have significant implications for their evolutionary dynamics and outbreak risks in future climate change scenarios. Electronic supplementary material The online version of this article (10.1186/s12898-018-0173-0) contains supplementary material, which is available to authorized users.

The exact relationship between the bending solutions of functionally graded material (FGM) beams based on the Levinson beam theory and those of the corresponding homogenous beams based on the classical beam theory is presented for the material properties of the FGM beams changing continuously in the thickness direction. The deflection, the rotational angle, the bending moment, and the shear force of FGM Levinson beams (FGMLBs) are given analytically in terms of the deflection of the reference homogenous Euler-Bernoulli beams (HEBBs) with the same loading, geometry, and end supports. Consequently, the solution of the bending of non-homogenous Levinson beams can be simplified to the calculation of transition coefficients, which can be easily determined by variation of the gradient of material properties and the geometry of beams. This is because the classical beam theory solutions of homogenous beams can be easily determined or are available in the textbook of material strength under a variety of boundary conditions. As examples, for different end constraints, particular solutions are given for the FGMLBs under specified loadings to illustrate validity of this approach. These analytical solutions can be used as benchmarks to check numerical results in the investigation of static bending of FGM beams based on higher-order shear deformation theories.

Epidermal stem cells could contribute to skin repair through the migration of cells from the neighboring uninjured epidermis, infundibulum, hair follicle, or sebaceous gland. However, little is known about the factors responsible for the complex biological processes in wound healing. Herein, we will show that the attracting chemokine, SDF-1/CXCR4, is a major regulator involved in the migration of epidermal stem cells during wound repair. We found that the SDF-1 levels were markedly increased at the wound margins following injury and CXCR4 expressed in epidermal stem cells and proliferating epithelial cells. Blocking the SDF-1/CXCR4 axis resulted in a significant reduction in epidermal stem cell migration toward SDF-1 in vitro and delayed wound healing in vivo, while an SDF-1 treatment enhanced epidermal stem cell migration and proliferation and accelerated wound healing. These results provide direct evidence that SDF-1 promotes epidermal stem cell migration, accelerates skin regeneration, and makes the development of new regenerative therapeutic strategies for wound healing possible.

Background In order to improve therapy for head and neck squamous cell carcinoma (HNSCC), biomarkers associated with local and/or distant tumor relapses and cancer drug resistance are urgently needed. This study identified a potential biomarker, Bcl-2 associated athanogene-1 (BAG-1), that is implicated in HNSCC insensitive to cisplatin and tumor progression. Methods Primary and advanced (relapsed from parental) University of Michigan squamous cell carcinoma cell lines were tested for sensitivity to cisplatin and gene expression profiles were compared between primary (cisplatin sensitive) and the relapsed (cisplatin resistant) cell lines by using Agilent microarrays. Additionally, differentially expressed genes phosphorylated AKT, and BAG-1, and BCL-xL were evaluated for expression using HNSCC tissue arrays. Results Advanced HNSCC cells revealed resistant to cisplatin accompanied by increased expression of BAG-1 protein. siRNA knockdown of BAG-1 expression resulted in significant improvement of HNSCC sensitivity to cisplatin. BAG-1 expression enhanced stability of BCL-xL and conferred cisplatin resistant to the HNSCC cells. In addition, high levels of expression of phosphorylated AKT, BAG-1, and BCL-xL were observed in advanced HNSCC compared to in that of primary HNSCC. Conclusion Increased expression of BAG-1 was associated with cisplatin resistance and tumor progression in HNSCC patients and warrants further validation in larger independent studies. Over expression of BAG-1 may be a biomarker for cisplatin resistance in patients with primary or recurrent HNSCCs and targeting BAG-1 could be helpful in overcoming cisplatin resistance. Electronic supplementary material The online version of this article (doi:10.1186/s12967-017-1289-2) contains supplementary material, which is available to authorized users.

Suppose that \(G\) is a finite group and \(H\), \(K\) are subgroups of \(G\). We say that \(H\) is weakly closed in \(K\) with respect to \(G\) if, for any \(g \in G\) such that \(H^{g}\le K\), we have \(H^{g}=H\). In particular, when \(H\) is a subgroup of prime-power order and \(K\) is a Sylow subgroup containing it, \(H\) is simply said to be a weakly closed subgroup of \(G\) or weakly closed in \(G\). In the paper, we investigate the structure of finite groups by means of weakly closed subgroups.

Free vibration of functionally graded beams with a through-width delamination is investigated. It is assumed that the material property is varied in the thickness direction as power law functions and a single through-width delamination is located parallel to the beam axis. The beam is subdivided into three regions and four elements. Governing equations of the beam segments are derived based on the Timoshenko beam theory and the assumption of ‘constrained mode’. By using the differential quadrature element method to solve the eigenvalue problem of ordinary differential equations governing the free vibration, numerical results for the natural frequencies of the beam are obtained. Natural frequencies of delaminated FGM beam with clamped ends are presented. Effects of parameters of the material gradients, the size and location of delamination on the natural frequency are examined in detail.

Hypertrophic scar (HS) remains a major problem in plastic surgery. In order to explore the regulative effect of phosphatase and tensin homolog (PTEN) on HS, PTEN and AKT expression was detected by reverse transcription PCR, immunohistochemistry and western blot. Adenovirus-mediated PTEN overexpression in cultured hypertrophic scar fibroblasts (HSFBs) and normal skin fibroblasts was also introduced to evaluate its biological function. Our results showed that PTEN expression was significantly decreased in HS whereas p-Akt level was significantly higher in HS compared with normal skin (P < 0.01). Furthermore, we found that adenovirus-mediated PTEN overexpression led to decreased AKT activation, and significantly reduced cell proliferation and collagen synthesis of HSFBs, while increased the apoptosis. Taken together, these data suggest that PTEN inhibits proliferation and function of HSFBs through AKT pathway. Our results reveal a novel biological role for PTEN/AKT pathway in HS and suggest PTEN as a potential therapeutic target for HS treatment.

Let G be a finite group. A subgroup H of G is called a CAP-subgroup if the following condition is satisfied: for each chief factor K/L of G either HK = HL or H ∩ K = H ∩ L. Let p be a prime factor of |G| and let P be a Sylow p-subgroup of G. If d is the minimum number of generators of P then there exists a family of maximal subgroups of P, denoted by Md(P)={P1, P2,…, Pd} such that ∩i=1dPi= ϕ(P). In this paper, we investigate the group G satisfying the condition: every member of a fixed Md(P) is a CAP-subgroup of G. For example, if, in addition, G is p-solvable, then G is p-supersolvable.

If H is a subgroup of a finite group G then we denote the normal closure of H in G by HG. We call G a PE-group if every minimal subgroup X of G satisfies NG(X) ∩ XG = X. The authors classify the finite non-PE-groups whose maximal subgroups of even order are PE-groups.

The class ℱpc of all finite groupsG is defined such thatX≤G implies that there exists an ℱ-subnormal subgroupS ofG containingX such thatX is ℱ-subabnormal inS, where ℱ is a saturated formation, closed under taken subgroups. Groups in ℱpc are characterized by ℱ-projectors and ℱ-covering subgroups.