Manipulating topological transformations of polar structures through real-time observation of the dynamic polarization evolution

Topological structures based on controllable ferroelectric or ferromagnetic domain configurations offer the opportunity to develop microelectronic devices such as high-density memories. Despite the increasing experimental and theoretical insights into various domain structures (such as polar spirals, polar wave, polar vortex) over the past decade, manipulating the topological transformations of polar structures and comprehensively understanding its underlying mechanism remains lacking. By conducting an in-situ non-contact bias technique, here we systematically investigate the real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers at an atomic level. The procedure of vortex pair splitting and the transformation from polar vortex to polar wave and out-of-plane polarization are observed step by step. Furthermore, the redistribution of charge in various topological structures has been demonstrated under an external bias. This provides new insights for the symbiosis of polar and charge and offers an opportunity for a new generation of microelectronic devices.

Direct observation of the dynamic evolution of polar domain structures at atomic level remains challenging. Here, the authors report the observation of real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers.

Supermicrosurgical reconstruction of nasal tip defects using the preauricular reversed superficial temporal artery flap

BACKGROUND

Microsurgical reconstruction of nasal tip defects is difficult to achieve. The free composite auricular flap allows for repair in a one-stage procedure. However, anastomosis to the recipient facial artery is often complicated because of its variable anatomy and the need for a vessel graft. In this study, we describe our experience using the alar artery and angular vein as recipient vessels for direct super microsurgical anastomosis.

METHOD

From February 2004 to December 2015, thirty-two patients with different degrees of full-thickness multi-subunit nasal tip defects were included in this study. The superficial temporal vessels, alar artery, and angular vein were marked preoperatively by ultrasound detection. The preauricular reversed superficial temporal artery flap was harvested and transferred to the nasal tip defect region as a free flap using a supermicrosurgical technique. Patient pictures were taken before surgery and at 1, 3, and 6 months of follow-up. Outcomes and complications were recorded and analyzed. Moreover, a postoperative patient satisfaction survey was performed.

RESULTS

The reversed superficial temporal artery flap was used in a total of 32 patients for the reconstruction of nasal tip defects in a one-stage procedure. In all cases, the alar artery and angular vein showed no anatomical variations and were used as recipient vessels. The size of the harvested preauricular flap size was 2.5 × 2.0 to 4.0 × 3.6 cm², and the average flap size was 3.6 × 2.7 cm². The length of the arterial pedicle was 4.0 to 6.7 cm, 5.58 cm on average. The length of the venous pedicle was 5.0 to 6.8 cm, 6.21 cm on average. Direct anastomosis was achieved in all patients, and in none of the cases, a vascular graft was needed. Donor sites were all closed primarily. Flap survival was complete, except for one case of vascular thrombosis, resulting in a 10% flap necrosis. Temporary hematoma was noted in one patient. The postoperative outcome showed excellent functional coverage and improved esthetic appearance. The average follow-up period was 12 months. The majority of patients (98.5%) rated their postoperative outcome as highly improved and improved. No late recurrence or other complications were seen in any of the patients. Twenty-two patients underwent a secondary debulking procedure of the flap for fine adjustment.

CONCLUSION

Our results demonstrate that the alar artery and angular vein are suitable recipient vessels for the super microsurgical reconstruction of nasal tip defects. Surgical planning and procedure are facilitated by their reliable anatomy without the need for a vessel graft. This technique may offer wider applications by extension to other facial cutaneous defects.

Optical creation of a supercrystal with three-dimensional nanoscale periodicity

Stimulation with ultrafast light pulses can realize and manipulate states of matter with emergent structural, electronic and magnetic phenomena. However, these non-equilibrium phases are often transient and the challenge is to stabilize them as persistent states. Here, we show that atomic-scale PbTiO₃/SrTiO₃ superlattices, counterpoising strain and polarization states in alternate layers, are converted by sub-picosecond optical pulses to a supercrystal phase. This phase persists indefinitely under ambient conditions, has not been created via equilibrium routes, and can be erased by heating. X-ray scattering and microscopy show this unusual phase consists of a coherent three-dimensional structure with polar, strain and charge-ordering periodicities of up to 30 nm. By adjusting only dielectric properties, the phase-field model describes this emergent phase as a photo-induced charge-stabilized supercrystal formed from a two-phase equilibrium state. Our results demonstrate opportunities for light-activated pathways to thermally inaccessible and emergent metastable states.

Intracellular manipulation and measurement with multipole magnetic tweezers

The capability to directly interrogate intracellular structures inside a single cell for measurement and manipulation is important for understanding subcellular and suborganelle activities, diagnosing diseases, and developing new therapeutic approaches. Compared with measurements of single cells, physical measurement and manipulation of subcellular structures and organelles remain underexplored. To improve intracellular physical measurement and manipulation, we have developed a multipole magnetic tweezers system for micromanipulation involving submicrometer position control and piconewton force control of a submicrometer magnetic bead inside a single cell for measurement in different locations (spatial) and different time points (temporal). The bead was three-dimensionally positioned in the cell using a generalized predictive controller that addresses the control challenge caused by the low bandwidth of visual feedback from high-resolution confocal imaging. The average positioning error was quantified to be 0.4 μm, slightly larger than the Brownian motion–imposed constraint (0.31 μm). The system is also capable of applying a force up to 60 pN with a resolution of 4 pN for a period of time longer than 30 min. The measurement results revealed that significantly higher stiffness exists in the nucleus’ major axis than in the minor axis. This stiffness polarity is likely attributed to the aligned actin filament. We also showed that the nucleus stiffens upon the application of an intracellularly applied force, which can be attributed to the response of structural protein lamin A/C and the intracellular stress fiber actin filaments.

A simple technique for the correction of maxillonasal dysplasia using customized expanded polytetrafluoroethylene (ePTFE) implants

BACKGROUND

The treatment of maxillonasal dysplasia in Binder's syndrome using autologous costal bone and cartilage is well established, but postoperative results may be compromised by scarring, unpredictable absorption of transferred autologous tissue, and donor site morbidity. Here, we propose a simple surgical technique to improve maxillonasal dysplasia using an expanded polytetrafluoroethylene (ePTFE) implant.

MATERIALS AND METHODS

From February 1999 to May 2014, fifty-eight patients affected by maxillonasal dysplasia with different degrees of flattened nose and midfacial depression underwent surgical correction by augmentation of the nasal dorsum using an "L"-shaped ePTFE and subperiosteal implantation of an inverted "m"-shaped ePTFE at the base of the piriform aperture. The outcome was evaluated based on preoperative and postoperative patient pictures, 3D imaging technology for the assessment of nasolabial angle and facial convexity angle, and a postoperative patient satisfaction survey.

RESULTS

Postoperative results showed improved facial aesthetics with a significantly increased nasolabial angle from initially 74.1° ± 8.9° to 93.7° ± 6.1° at 6 months postoperatively (p < 0.05). Temporary discomfort involving upper lip numbness, foreign body sensation, and stiff smiling expression were complained during the first 3 months postoperatively, but spontaneously resolved within 6 months. Complications included infection (2 cases), implant migration (2 cases), and implant exposure (1 case). The vast majority of patients (95.7%) rated their postoperative outcome as highly improved and improved.

CONCLUSION

The present therapeutic strategy provides a simple and effective treatment for the correction of maxillonasal dysplasia with high patient acceptance in a single step approach. Further research is required to determine long-term outcomes.

Early diagnosis and outcome prediction of neonatal hypoxic-ischemic encephalopathy with color Doppler ultrasound

PURPOSE

To describe the ultrasound presentation of the brain and cerebral hemodynamics in neonates with hypoxic-ischemic encephalopathy (HIE) by comparison with control subjects.

MATERIAL AND METHODS

During June 2012 to April 2013, full term neonates who had clinical evidence of HIE were enrolled. Healthy newborns without HIE were used as a control group. Cerebral parenchyma, size of lateral ventricles and hemodynamic parameters of cerebral arteries were studied using two-dimensional duplex and color Doppler ultrasound. Neonates with moderate and severe HIE were followed-up with ultrasound for at least 3 months.

RESULTS

A total of 158 consecutive neonates (82 boys and 76 girls), including 54 with mild HIE, 60 with moderate HIE and 44 with severe HIE were included. One hundred and twenty healthy newborns were randomly selected as a control group. Abnormal ultrasound findings of brain parenchyma were found in 25/54 (46.3%) neonates with mild HIE whereas they were found in 58/60 (96.7%) neonates with moderate HIE and 44/44 (100%) neonates with severe HIE. Almost all neonates with severe HIE had decreased cerebral artery blood flow velocity and increased resistance index of cerebral arteries. Of the 104 neonates with moderate or severe HIE, follow-up ultrasound examination revealed cystic parenchymal lesions in 12/104 (11.5%), progressive ventricular dilatation and brain atrophy in 12/104 (11.5%), mild ventricular dilatation in 15/104 (14.4%) and leukoencephalomalacia in 2/104 (1.9%) neonates.

CONCLUSION

Ultrasound features such as the size of lateral ventricles, altered brain parenchymal echogenicity and cerebral blood flow parameters are useful for the early diagnosis of HIE and help predict outcome.

Autologous temporomandibular joint reconstruction independent of exogenous additives: a proof-of-concept study for guided self-generation

Joint defects are complex and difficult to reconstruct. By exploiting the body’s own regenerative capacity, we aimed to individually generate anatomically precise neo-tissue constructs for autologous joint reconstruction without using any exogenous additives. In a goat model, CT scans of the mandibular condyle including articular surface and a large portion of the ascending ramus were processed using computer-aided design and manufacturing. A corresponding hydroxylapatite negative mold was printed in 3D and temporarily embedded into the transition zone of costal periosteum and perichondrium. A demineralized bone matrix scaffold implanted on the contralateral side served as control. Neo-tissue constructs obtained by guided self-generation exhibited accurate configuration, robust vascularization, biomechanical stability, and function. After autologous replacement surgery, the constructs showed stable results with similar anatomical, histological, and functional findings compared to native controls. Further studies are required to assess long-term outcome and possible extensions to other further applications. The absence of exogenous cells, growth factors, and scaffolds may facilitate clinical translation of this approach.

Treatment of gummy smile: Nasal septum dysplasia as etiologic factor and therapeutic target

Various techniques to improve gummy smile exist. Depending on the individual etiology, previous approaches have focused on osseous, dental, and soft-tissue aspects. On the basis of the identification of nasal septum dysplasia as etiologic factor of gummy smile, we propose a novel strategy for the improvement in the treatment of excessive gingival exposure. In this prospective controlled study, 121 Asian patients with gummy smile and 150 volunteers were examined and compared with regard to the developmental status of the nasal septal cartilage reflected by the columella upward maximum movability (CUMM) as objective measurement parameter. A total of 46 patients with significantly increased CUMM underwent surgical treatment for excessive gingival exposure by septum cartilage reinforcement and, where required, additional extension using an autologous cartilage graft or an expanded polytetrafluoroethylene (ePTFE) implant. Gingival exposure at the fullest smile was photographed, measured, and analyzed before and 1, 3, and 6 months after surgery, and all possible complications were recorded. The results were evaluated in a patient satisfaction survey. CUMM showed a significant statistical difference between the patients desiring treatment for gummy smile (5.6 ± 0.92 mm) and volunteers (3.1 ± 0.76 mm), (p < 0.05). In the 46 patients who underwent surgical correction of gummy smile, the measured maximum gingival exposure at the fullest smile was 4.52 ± 1.7 mm preoperatively and significantly decreased to 1.79 ± 0.26 mm at 6 months postoperatively (p < 0.05). The overall complication rate was low, including transient stiffness of smile, implant deformation, and acute infection. The postoperative results were highly satisfactory in terms of aesthetic smile. This study proposes a novel strategy of reinforcement and extension of the nasal septum cartilage for the improvement of gummy smile confirming septal cartilage dysplasia as the etiologic factor.

Negative regulation of the p300-p53 interplay by DDX24

Numerous studies indicate that p300 acts as a key transcriptional cofactor in vivo, at least, in part, through modulating activities of p53 by acetylation. Nevertheless, the regulation of the p53-p300 interplay is not completely understood. Here, we have identified the DEAD box RNA helicase DDX24 as a novel regulator of the p300-p53 axis. We found that DDX24 interacts with p300, and this interaction leads to suppression of p300 mediated acetylation of p53. Notably, RNAi-mediated knockdown of endogenous DDX24 significantly increases the acetylation levels of endogenous p53 in human cancer cells and subsequently promotes p53-mediated activation of its transcriptional targets such as p21 and PUMA. In contrast, DDX24 expression inhibits the p300-p53 interaction and suppresses p300-mediated acetylation of p53. Moreover, DDX24 is overexpressed in human cancer cells and reduction of DDX24 protein levels by RNAi induces cell cycle arrest and senescence in a p53 dependent manner. These results reveal DDX24 as an important regulator of p300 and suggest that the modulation of the p53-p300 interplay by DDX24 is critical in controlling p53 activities in human cancer cells.

An integrated simulation and optimization approach for managing human health risks of atmospheric pollutants by coal-fired power plants

This research developed a simulation-aided nonlinear programming model (SNPM). This model incorporated the consideration of pollutant dispersion modeling, and the management of coal blending and the related human health risks within a general modeling framework In SNPM, the simulation effort (i.e., California puff [CALPUFF]) was used to forecast the fate of air pollutants for quantifying the health risk under various conditions, while the optimization studies were to identify the optimal coal blending strategies from a number of alternatives. To solve the model, a surrogate-based indirect search approach was proposed, where the support vector regression (SVR) was used to create a set of easy-to-use and rapid-response surrogates for identifying the function relationships between coal-blending operating conditions and health risks. Through replacing the CALPUFF and the corresponding hazard quotient equation with the surrogates, the computation efficiency could be improved. The developed SNPM was applied to minimize the human health risk associated with air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicated that it could be used for reducing the health risk of the public in the vicinity of the two power plants, identifying desired coal blending strategies for decision makers, and considering a proper balance between coal purchase cost and human health risk.

IMPLICATIONS

A simulation-aided nonlinear programming model (SNPM) is developed. It integrates the advantages of CALPUFF and nonlinear programming model. To solve the model, a surrogate-based indirect search approach based on the combination of support vector regression and genetic algorithm is proposed. SNPM is applied to reduce the health risk caused by air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicate that it is useful for generating coal blending schemes, reducing the health risk of the public, reflecting the trade-offbetween coal purchase cost and health risk.

Anti-TNF-α therapy for patients with sepsis: a systematic meta-analysis

OBJECTIVE

In humans, the role of anti-tumour necrosis factor (TNF)-α therapy in severe sepsis and septic shock is debatable. The aim of this meta-analysis was to determine the efficacy of anti-TNF-α therapies against placebo in patients with severe sepsis or septic shock.

METHODS

A structured literature search was undertaken to identify randomised controlled trials (RCTs) conducted in patients with severe sepsis or septic shock receiving anti-TNF-α therapy or placebo. A meta-analysis on relative risk (OR) with a 95% confidence interval (95% CI) was performed.

RESULTS

Seventeen studies with a total of 8971 patients were included. When all forms of anti-TNF-α therapy were pooled together, there was a significant reduction of 28-day all-cause mortality with respect to placebo (OR = 0.91, 95% CI: 0.83-0.99; p = 0.04). Subgroup analysis showed that anti-TNF-α antibodies (monoclonal and polyclonal) reduced mortality (OR = 0.90, 95% CI: 0.81-0.99; p = 0.04). Monoclonal antibodies enhanced survival (OR = 0.91, 95% CI: 0.82-1.00; p = 0.05), while polyclonal antibodies or receptor blockers did not enhance survival (OR = 0.71, 95% CI: 0.39-1.28, p = 0.25; OR = 0.95, 95% CI: 0.78-1.17, p = 0.65). There was a trend towards better survival in patients with high levels of IL-6 (> 1000 pg/ml) and patients with shock if they were treated with anti-TNF-α therapy (OR = 0.85, 95% CI: 0.72-1.00; OR = 0.80, 95% CI: 0.62-1.04). Publication bias and statistical heterogeneity (I(2)  < 50% and p > 0.1) were absent. Sensitivity analysis suggests that these results are highly stable.

CONCLUSIONS

This meta-analysis suggests that in patients with severe sepsis (before shock), immunotherapy with anti-TNF-α monoclonal antibodies reduces overall mortality. In patients with shock or high levels of IL-6 (> 1000 pg/ml), anti-TNF-α therapy may improve survival.