Pyogenic spondylitis caused by Escherichia coli: A case report and literature review.

BACKGROUND: Pyogenic spondylitis is often manifested as atypical low back pain and fever, which makes it easy to be confused with other diseases. Here we report a case of pyogenic spondylitis and describe the diagnosis and treatment based on the related literature. CASE SUMMARY: The reported case suffered from pyogenic spondylitis caused by Escherichia coli and complicated with bacteremia and psoas abscess. Acute pyelonephritis was initially diagnosed due to atypical symptoms. Symptoms were improved from antibiotic treatment while developing progressive lower limb dysfunction. One month post the admission, the patient underwent anterior lumbar debridement + autogenous iliac bone graft fusion + posterior percutaneous screw-rod internal fixation, and received 6 wk of antibiotic treatment after the operation. Reexamination 4 mo post the operation showed that the patient had no evident pain in the waist, and walked well with no evident dysfunction of lower limbs. CONCLUSION: Here we describe the application value of several imaging examinations, such as X-ray, computed tomography and magnetic resonance imaging, and certain tests like erythrocyte sedimentation rate and C-reactive protein in the clinical treatment of pyogenic spondylitis. This disease requires early diagnosis and treatment. Sensitive antibiotics should be used in early stages and surgical intervention should be taken if necessary, which may help for a speedy recovery and prevent the occurrence of severe complications.

Suppressing Structural Relaxation in Nanoscale Antimony to Enable Ultralow-Drift Phase-Change Memory Applications.

Phase-change random-access memory (PCRAM) devices suffer from pronounced resistance drift originating from considerable structural relaxation of phase-change materials (PCMs), which hinders current developments of high-capacity memory and high-parallelism computing that both need reliable multibit programming. This work realizes that compositional simplification and geometrical miniaturization of traditional GeSbTe-like PCMs are feasible routes to suppress relaxation. While to date, the aging mechanisms of the simplest PCM, Sb, at nanoscale, have not yet been unveiled. Here, this work demonstrates that in an optimal thickness of only 4 nm, the thin Sb film can enable a precise multilevel programming with ultralow resistance drift coefficients, in a regime of ≈10-4 -10-3 . This advancement is mainly owed to the slightly changed Peierls distortion in Sb and the less-distorted octahedral-like atomic configurations across the Sb/SiO2 interfaces. This work highlights a new indispensable approach, interfacial regulation of nanoscale PCMs, for pursuing ultimately reliable resistance control in aggressively-miniaturized PCRAM devices, to boost the storage and computing efficiencies substantially.

Mid-Term Outcomes of Arthroscopic Rotator Cuff Repair in Patients with Rheumatoid Arthritis.

OBJECTIVE: The effectiveness of arthroscopic rotator cuff repair (ARCR) on rheumatoid arthritis (RA) patients remains a controversial topic. This study investigates the mid-term outcomes of ARCR in RA patients and identifies the factors influencing clinical efficacy. METHODS: This retrospective study enrolled RA patients with small or medium rotator cuff tears (RCTs) between February 2014 and February 2019. Visual Analog Scale (VAS), American Shoulder and Elbow Surgeons (ASES), and Constant-Murley scores were collected at each follow-up time. Ultimately, magnetic resonance imaging (MRI) and X-ray were employed to assess rotator cuff integrity and progression of shoulder bone destruction, respectively. Statistical methods used two-way repeated-measures ANOVA or generalized estimation equations. RESULTS: A total of 157 patients were identified and divided into ARCR (n = 75) and conservative treatment (n = 82) groups. ARCR group continued to be divided into small tear (n = 35) and medium tear (n = 40) groups. At the final, all scores were better in ARCR group than in the conservative treatment group (p < 0.05). A radiographic evaluation of the final follow-up demonstrated that the progression rate in ARCR group (18.67%) was significantly lower than that of the conservative treatment group (39.02%, p < 0.05). In the comparison of the small tear and medium tear groups, all scores increased significantly after surgery (p < 0.05), and the final follow-up scores were better than preoperative scores (p < 0.05) but worse than those of the 6-month postoperative follow-up (p < 0.05). Comparison between the two groups revealed that all scores of the small tear group were significantly better than those of the medium tear group at 6-month postoperative follow-up (p < 0.05). Although the scores of small tear group remained better than those of the medium group at the final postoperative follow-up, the difference was not statistically significant (p > 0.05). Radiographic assessment of the final follow-up demonstrated that the progression rate in the small tear group (8.57%) was significantly lower than that in the medium group (27.50%, p < 0.05), and the retear rate of small tear group (14.29%) was significantly lower than that of the medium tear group (35.00%, p < 0.05). CONCLUSION: ARCR could effectively improve the quality of life for RA patients with small or medium RCTs, at least in the medium term. Despite the progression of joint destruction in some patients, postoperative retear rates were comparable to those in the general population. ARCR is more likely to benefit RA patients than conservative treatment.

Ultrafast dynamics of spin relaxation in monolayer WSe2 and the WSe2/graphene heterojunction.

Excitonic devices based on two-dimensional (2D) transition metal dichalcogenides (TMDCs) can combine spintronics with valleytronics due to its special energy band structure. In this work, we studied the generation and relaxation processes of spin/valley polarized excitons dynamics in monolayer WSe2 and its van der Waals (vdW) heterojunction with graphene using a circularly polarized femtosecond pump-probe system. The spin/valley depolarization dynamics of the A exciton in monolayer WSe2 is found to exhibit a biexponential decay. The fast relaxation process is due to the ultrafast intervalley electron-hole spin-flip exchange coupling and electron-phonon scattering. And the slow relaxation process originates from the recombination and relaxation of the trion states. Graphene has an electron extraction effect on WSe2, which prevents the formation of trions. Therefore, the spin/valley depolarization process of the A exciton in the heterojunction exhibits only a fast relaxation process. In both monolayer WSe2 and its heterojunction with graphene, B/A' excitons exhibit a negative spin/valley polarization which is mainly due to two-photon absorption and excited Bose scattering. Our work systematically studied the spin/valley depolarization dynamics of excitons and revealed possible mechanisms of their differences in isolated 2D WSe2 and vdW heterojunctions.

Phase-Change-Memory Process at the Limit: A Proposal for Utilizing Monolayer Sb2Te3.

One central task of developing nonvolatile phase change memory (PCM) is to improve its scalability for high-density data integration. In this work, by first-principles molecular dynamics, to date the thinnest PCM material possible (0.8 nm), namely, a monolayer Sb2Te3, is proposed. Importantly, its SET (crystallization) process is a fast one-step transition from amorphous to hexagonal phase without the usual intermediate cubic phase. An increased spatial localization of electrons due to geometrical confinement is found to be beneficial for keeping the data nonvolatile in the amorphous phase at the 2D limit. The substrate and superstrate can be utilized to control the phase change behavior: e.g., with passivated SiO2 (001) surfaces or hexagonal Boron Nitride, the monolayer Sb2Te3 can reach SET recrystallization in 0.54 ns or even as fast as 0.12 ns, but with unpassivated SiO2 (001), this would not be possible. Besides, working with small volume PCM materials is also a natural way to lower power consumption. Therefore, the proposed PCM working process at the 2D limit will be an important potential strategy of scaling the current PCM materials for ultrahigh-density data storage.

Pioglitazone alleviates cisplatin nephrotoxicity by suppressing mitochondria-mediated apoptosis via SIRT1/p53 signalling.

Pioglitazone (PIO) attenuates cisplatin nephrotoxicity whereas the underlying mechanism remains unknown. Apoptosis is associated with mitochondrial dysfunction and SIRT1 activation can decrease cell apoptosis in cisplatin nephrotoxicity. Therefore, we explored whether the protective effect of PIO in cisplatin nephrotoxicity is achieved by suppressing mitochondria-mediated apoptosis through SIRT1/p53 signalling regulation. Cell viability, apoptosis, survival rate, renal pathology and function were examined. Moreover, we also analysed the expression of SIRT1, Acetyl-p53, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), mitochondrial permeability transition pore (mPTP) opening, adenosine triphosphate (ATP) and apoptosis-related protein in vivo and in vitro. Pioglitazone treatment significantly increased cell viability, promoted SIRT1-p53 interaction, upregulated Bcl-2 expression, activated SIRT1 and elevated mitochondrial ATP synthesis after cisplatin treatment. However, PIO decreased the generation of ROS, opening of mPTP, dissipation of MMP and translocation of cytochrome c after cisplatin treatment. Pioglitazone also reduced the activation of caspase-3 and caspase-9, lowered the ratio of Bax/Bcl-2, attenuated kidney pathological damage and dysfunction, down-regulated the expression of Acetyl-p53, PUMA-α and Bax and abated cell apoptosis after cisplatin treatment. The SIRT1 inhibitor, EX527, clearly reversed the protective effects of PIO. These results implied PIO attenuated cisplatin nephrotoxicity by suppressing mitochondria-mediated apoptosis through regulating SIRT1/p53 signalling.

A lysin motif-containing protein (SpLysMD3) functions as a PRR involved in the antibacterial responses of mud crab, Scylla paramamosain.

Lysin motif (LysM)-containing proteins function as pattern-recognition receptors in plants to recognize different N-acetylglucosamine-containing ligands, thereby triggering specific defense responses against pathogens. However, the biological functions of these proteins in animals remain unclear. In this study, we characterized a novel LysM protein, designated as SpLysMD3, in mud crab Scylla paramamosain. The cDNA sequence of SpLysMD3 had 1058 bp with an open reading frame of 840 bp encoding a protein with 279 amino acid residues. The deduced protein contained a LysM domain and a transmembrane region. SpLysMD3 was highly expressed in gills, intestine, muscle, and hemocytes and upregulated after challenges with bacteria, suggesting that it may be involved in antibacterial defense. Binding assay showed that SpLysMD3 possessed specific binding activities to all tested microorganisms as well as bacterial cell wall components lipopolysaccharide (LPS) and peptidoglycan (PGN), indicating that SpLysMD3 was an important LPS- and PGN-binding protein in mud crab. Bacterial clearance assay revealed that coating bacteria with SpLysMD3 accelerated bacterial clearance in vivo. The promotion of bacterial clearance by SpLysMD3 was further determined by using SpLysMD3-silenced crabs injected with S. aureus or V. parahemolyticus. Silencing SpLysMD3 dramatically suppressed the bacterial clearance. Meanwhile, knockdown of SpLysMD3 also severely impaired the expression of a specific set of antimicrobial peptides (AMPs); moreover, SpLysMD3 overexpression can enhance the promoter activity of SpALF2. These results suggested that SpLysMD3 affected bacterial clearance by regulating AMPs. Collectively, all the results demonstrated that SpLysMD3 may function as a potential receptor involved in innate immunity by binding to LPS and PGN and by regulating AMPs to eliminate invading pathogen. This study provided new insights into the biological functions of LysM proteins in animals and the mechanisms underlying the antibacterial activity of crustaceans.

Non-phase-separated 2D B-C-N alloys via molecule-like carbon doping in 2D BN: atomic structures and optoelectronic properties.

Two-dimensional (2D) B-C-N alloys have recently attracted much attention but unfortunately, Chemical Vapor Deposition (CVD) B-C-N alloys typically phase separate. In spite of that, our analysis of the B-C-N alloy fabricated by electron-beam irradiation suggests that non-phase-separated B-C-N may in fact exist with a carbon concentration up to 14 at%. While this analysis points to a new way to overcome the phase-separation in 2D B-C-N, by first-principles calculations, we show that these B-C-N alloys are made of motifs with even numbers of carbon atoms, in particular, dimers or six-fold rings (in a molecule-like form), embedded in a 2D BN network. Moreover, by tuning the carbon concentration, the band gap of the B-C-N alloys can be reduced by 35% from that of BN. Due to a strong overlap of the wavefunctions at the conduction band and valance band edges, the non-phase-separated B-C-N alloys maintain the strong optical absorption of BN.

Clarification of the Molecular Doping Mechanism in Organic Single-Crystalline Semiconductors and their Application in Color-Tunable Light-Emitting Devices.

Organic single-crystalline semiconductors with long-range periodic order have attracted much attention for potential applications in electronic and optoelectronic devices due to their high carrier mobility, highly thermal stability, and low impurity content. Molecular doping has been proposed as a valuable strategy for improving the performance of organic semiconductors and semiconductor-based devices. However, a fundamental understanding of the inherent doping mechanism is still a key challenge impeding its practical application. In this study, solid evidence for the "perfect" substitutional doping mechanism of the stacking mode between the guest and host molecules in organic single-crystalline semiconductors using polarized photoluminescence spectrum measurements and first-principles calculations is provided. The molecular host-guest doping is further exploited for efficient color-tunable and even white organic single-crystal-based light-emitting devices by controlling the doping concentration. The clarification of the molecular doping mechanism in organic single-crystalline semiconductor host-guest system paves the way for their practical application in high-performance electronic and optoelectronic devices.

Investigating the dynamics of excitons in monolayer WSe2 before and after organic super acid treatment.

Due to the large photoluminescence quantum yield, high mobility and good stability, organic super acid treated two-dimensional WSe2 has drawn much attention. However, reports about the influence of organic super acid treatment on the dynamic processes of excitons of monolayer WSe2 are still rare. In this work, through the broadband transient absorption spectra obtained using a femtosecond pump-probe system, we determine the dynamics of A' and C excitons in monolayer and bulk WSe2 at room temperature. Besides this, we also observe the relaxation process of the holes between the two spin split states in the valence band maximum in organic super acid treated monolayer WSe2. We find that the organic super acid treatment on monolayer WSe2 does not change the peak positions of the exciton states, while those bleaching peaks' intensities increase significantly due to the enhancement of oscillator strength for exciton states, corresponding to stronger steady-state photoluminescence. This could be attributed to the strain release induced by the defect repairing effect during the organic super acid treatment process.

Directional Forces by Momentumless Excitation and Order-to-Order Transition in Peierls-Distorted Solids: The Case of GeTe.

Time-dependent density-functional theory molecular dynamics reveals an unexpected effect of optical excitation in the experimentally observed rhombohedral-to-cubic transition of GeTe. The excitation induces coherent forces along [001], which may be attributed to the unique energy landscape of Peierls-distorted solids. The forces drive the A_{1g} optical phonon mode in which Ge and Te move out of phase. Upon damping of the A_{1g} mode, phase transition takes place, which involves no atomic diffusion, defect formation, or the nucleation and growth of the cubic phase.

Electric field analyses on monolayer semiconductors: the example of InSe.

External electric fields can be used to manipulate the electronic properties of two-dimensional (2D) materials. 2D InSe semiconductors possess high electron mobility and wide band gap tunability. Therefore, they have been proposed for use in ultrathin electronic devices. Here, using first-principles calculations, we study the charge polarization, structure, electronic structure, and gas adsorption of an InSe monolayer under vertical electric fields. We find that both the structural evolution and charge polarization rely on the directions of the electric fields. The hole effective mass at the valance band maximum can be decreased by fields that offer a possible route to increase mobility. In contrast, the fields have little impact on the effective mass of electrons at the conduction band minimum. Therefore, high electron mobility in InSe is retained under the fields. Besides, electric fields could alter the absorption intensity for gas molecules. Therefore, gas sensors could be an expected application. More importantly, this work systematically points out some key steps for setting up electric-field calculations in the popular VASP code, such as the cancellation of the symmetrisation of the charge density, avoiding electrons spilling out into the vacuum under high fields.

Rat embryonic stem cells produce fertile offspring through tetraploid complementation.

Pluripotency of embryonic stem cells (ESCs) can be functionally assessed according to the developmental potency. Tetraploid complementation, through which an entire organism is produced from the pluripotent donor cells, is taken as the most stringent test for pluripotency. It remains unclear whether ESCs of other species besides mice can pass this test. Here we show that the rat ESCs derived under 2i (two small molecule inhibitors) conditions at very early passages are able to produce fertile offspring by tetraploid complementation. However, they lose this capacity rapidly during culture due to a nearly complete loss of genomic imprinting. Our findings support that the naïve ground state pluripotency can be captured in rat ESCs but also point to the species-specific differences in its regulation and maintenance, which have implications for the derivation and application of naïve pluripotent stem cells in other species including human.

Giant lattice expansion by quantum stress and universal atomic forces in semiconductors under instant ultrafast laser excitation.

Femtosecond lasers (fs) can cause a disparity between electronic and lattice temperatures in the very short period after irradiation. In this relatively cool lattice regime, the material properties can differ drastically from those under thermal equilibrium. In particular, first-principles calculations reveal two general mechanical effects on semiconductors. Firstly, the excitation can induce a negative pressure on the lattice, causing a >10% expansion, even for superhard diamond. Secondly, it induces inhomogeneous local forces on the atoms, for both perfect and distorted lattices. In the case of phase-change-memory for Ge2Sb2Te5 and GeTe alloys, such random forces cause a simultaneous phase transition from crystalline to amorphous, which enables faster data writing. These excitation effects are further supported by the time-dependent density functional theory. This work could be an important step in advancing fs laser techniques for the atomic-level control of structures, rather than relying on traditional melting or ablation approaches which often apply to much larger and non-atomic scales.

Vacancy Structures and Melting Behavior in Rock-Salt GeSbTe.

Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological breakthrough in memory devices. Using spherical aberration-aberration corrected scanning transmission electron microscopy and atomic scale energy-dispersive X-ray mapping, we observe a new rock-salt structure with high-degree vacancy ordering (or layered-like ordering) at an elevated temperature, which is a result of phase transition from the rock-salt phase with randomly distributed vacancies. First-principles calculations reveal that the phase transition is an energetically favored process. Moreover, molecular dynamics studies suggest that the melting of the cubic rock-salt phases is initiated at the vacancies, which propagate to nearby regions. The observation of multi-rock-salt phases suggests another route for multi-level data storage using GeSbTe.

Role of the nano amorphous interface in the crystallization of Sb2Te3 towards non-volatile phase change memory: insights from first principles.

The nano amorphous interface is important as it controls the phase transition for data storage. Yet, atomic scale insights into such kinds of systems are still rare. By first-principles calculations, we obtain the atomic interface between amorphous Si and amorphous Sb2Te3, which prevails in the series of Si-Sb-Te phase change materials. This interface model reproduces the experiment-consistent phenomena, i.e. the amorphous stability of Sb2Te3, which defines the data retention in phase change memory, and is greatly enhanced by the nano interface. More importantly, this method offers a direct platform to explore the intrinsic mechanism to understand the material function: (1) by steric effects through the atomic "channel" of the amorphous interface, the arrangement of the Te network is significantly distorted and is separated from the p-orbital bond angle in the conventional phase-change material; and (2) through the electronic "channel" of the amorphous interface, high localized electrons in the form of a lone pair are "projected" to Sb2Te3 from amorphous Si by a proximity effect. These factors set an effective barrier for crystallization and improve the amorphous stability, and thus data retention. The present research and scheme sheds new light on the engineering and manipulation of other key amorphous interfaces, such as Si3N4/Ge2Sb2Te5 and C/Sb2Te3, through first-principles calculations towards non-volatile phase change memory.