Lattice Plainification Leads to High Thermoelectric Performance of P-Type PbSe Crystals.

Thermoelectrics has applications in power generation and refrigeration. Since only commercial Bi2Te3 has a low abundance Te, PbSe gets attention. This work enhances the near-room temperature performance of p-type PbSe through enhancing carrier mobility via lattice plainification. Composition controlled and Cu-doped p-type PbSe crystals are grown through physical vapor deposition. Results exhibit an enhanced carrier mobility ≈2578 cm2 V-1 s-1 for Pb0.996Cu0.0004Se. Microstructure characterization and density functional theory calculations verify the introduced Cu atoms filled Pb vacancies, realizing lattice plainification and enhancing the carrier mobility. The Pb0.996Cu0.0004Se sample achieves a power factor ≈42 µW cm-1 K-2 and a ZT ≈ 0.7 at 300 K. The average ZT of it reaches ≈0.9 (300-573 K), resulting in a single-leg power generation efficiency of 7.1% at temperature difference of 270 K, comparable to that of p-type commercial Bi2Te3. A 7-pairs device paired the p-type Pb0.996Cu0.0004Se with the n-type commercial Bi2Te3 shows a maximum cooling temperature difference ≈42 K with the hot side at 300 K, ≈65% of that of the commercial Bi2Te3 device. This work highlights the potential of p-type PbSe for power generation and refrigeration near room temperature and hope to inspire researchers on replacing commercial Bi2Te3.

Grid-plainification enables medium-temperature PbSe thermoelectrics to cool better than Bi2Te3.

Thermoelectric cooling technology has important applications for processes such as precise temperature control in intelligent electronics. The bismuth telluride (Bi2Te3)-based coolers currently in use are limited by the scarcity of Te and less-than-ideal cooling capability. We demonstrate how removing lattice vacancies through a grid-design strategy switched PbSe from being useful as a medium-temperature power generator to a thermoelectric cooler. At room temperature, the seven-pair device based on n-type PbSe and p-type SnSe produced a maximum cooling temperature difference of ~73 kelvin, with a single-leg power generation efficiency approaching 11.2%. We attribute our results to a power factor of >52 microwatts per centimeter per square kelvin, which was achieved by boosting carrier mobility. Our demonstration suggests a path for commercial applications of thermoelectric cooling based on Earth-abundant Te-free selenide-based compounds.

All-SnTe-Based Thermoelectric Power Generation Enabled by Stepwise Optimization of n-Type SnTe.

The practical application of thermoelectric devices requires both high-performance n-type and p-type materials of the same system to avoid possible mismatches and improve device reliability. Currently, environmentally friendly SnTe thermoelectrics have witnessed extensive efforts to develop promising p-type transport, making it rather urgent to investigate the n-type counterparts with comparable performance. Herein, we develop a stepwise optimization strategy for improving the transport properties of n-type SnTe. First, we improve the n-type dopability of SnTe by PbSe alloying to narrow the band gap and obtain n-type transport in SnTe with halogen doping over the whole temperature range. Then, we introduce additional Pb atoms to compensate for the cationic vacancies in the SnTe-PbSe matrix, further enhancing the electron carrier concentration and electrical performance. Resultantly, the high-ranged thermoelectric performance of n-type SnTe is substantially optimized, achieving a peak ZT of ∼0.75 at 573 K with a high average ZT (ZTave) exceeding 0.5 from 300 to 823 K in the (SnTe0.98I0.02)0.6(Pb1.06Se)0.4 sample. Moreover, based on the performance optimization on n-type SnTe, for the first time, we fabricate an all-SnTe-based seven-pair thermoelectric device. This device can produce a maximum output power of ∼0.2 W and a conversion efficiency of ∼2.7% under a temperature difference of 350 K, demonstrating an important breakthrough for all-SnTe-based thermoelectric devices. Our research further illustrates the effectiveness and application potential of the environmentally friendly SnTe thermoelectrics for mid-temperature power generation.

Large Mobility Enables Higher Thermoelectric Cooling and Power Generation Performance in n-type AgPb18+xSbTe20 Crystals.

The room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPb18+xSbTe20 crystals using a vertical Bridgman method. A large weighted mobility of ∼410 cm2 V-1 s-1 is achieved in the AgPb18.4SbTe20 crystal, which is almost 4 times higher than that of the polycrystalline counterpart due to the elimination of grain boundaries and Ag-rich dislocations verified by atom probe tomography, highlighting the significant benefit of growing crystals for low-temperature thermoelectrics. Due to the largely promoted weighted mobility, we achieve a high power factor of ∼37.8 µW cm-1 K-2 and a large figure of merit ZT of ∼0.6 in AgPb18.4SbTe20 crystal at 303 K. We further designed a 7-pair thermoelectric module using this n-type crystal and a commercial p-type (Bi, Sb)2Te3-based material. As a result, a high cooling temperature difference (ΔT) of ∼42.7 K and a power generation efficiency of ∼3.7% are achieved, revealing promising thermoelectric applications for PbTe-based materials near room temperature.

Lattice plainification advances highly effective SnSe crystalline thermoelectrics.

Thermoelectric technology has been widely used for key areas, including waste-heat recovery and solid-state cooling. We discovered tin selenide (SnSe) crystals with potential power generation and Peltier cooling performance. The extensive off-stoichiometric defects have a larger impact on the transport properties of SnSe, which motivated us to develop a lattice plainification strategy for defects engineering. We demonstrated that Cu can fill Sn vacancies to weaken defects scattering and boost carrier mobility, facilitating a power factor exceeding ~100 microwatts per centimeter per square kelvin and a dimensionless figure of merit (ZT) of ~1.5 at 300 kelvin, with an average ZT of ~2.2 at 300 to 773 kelvin. We further realized a single-leg efficiency of ~12.2% under a temperature difference (ΔT) of ~300 kelvin and a seven-pair Peltier cooling ΔTmax of ~61.2 kelvin at ambient temperature. Our observations are important for practical applications of SnSe crystals in power generation as well as electronic cooling.

High thermoelectric performance realized through manipulating layered phonon-electron decoupling.

Thermoelectric materials allow for direct conversion between heat and electricity, offering the potential for power generation. The average dimensionless figure of merit ZTave determines device efficiency. N-type tin selenide crystals exhibit outstanding three-dimensional charge and two-dimensional phonon transport along the out-of-plane direction, contributing to a high maximum figure of merit Zmax of ~3.6 × 10-3 per kelvin but a moderate ZTave of ~1.1. We found an attractive high Zmax of ~4.1 × 10-3 per kelvin at 748 kelvin and a ZTave of ~1.7 at 300 to 773 kelvin in chlorine-doped and lead-alloyed tin selenide crystals by phonon-electron decoupling. The chlorine-induced low deformation potential improved the carrier mobility. The lead-induced mass and strain fluctuations reduced the lattice thermal conductivity. Phonon-electron decoupling plays a critical role to achieve high-performance thermoelectrics.

Power generation and thermoelectric cooling enabled by momentum and energy multiband alignments.

Thermoelectric materials transfer heat and electrical energy, hence they are useful for power generation or cooling applications. Many of these materials have narrow bandgaps, especially for cooling applications. We developed SnSe crystals with a wide bandgap (E g ≈ 33 k B T) with attractive thermoelectric properties through Pb alloying. The momentum and energy multiband alignments promoted by Pb alloying resulted in an ultrahigh power factor of ~75 µW cm-1 K-2 at 300 K, and an average figure of merit ZT of ~1.90. We found that a 31-pair thermoelectric device can produce a power generation efficiency of ~4.4% and a cooling ΔT max of ~45.7 K. These results demonstrate that wide-bandgap compounds can be used for thermoelectric cooling applications.

Realizing N-type SnTe Thermoelectrics with Competitive Performance through Suppressing Sn Vacancies.

Due to the intrinsically plentiful Sn vacancies, developing n-type SnTe thermoelectric materials is a big challenge. Herein, n-type SnTe thermoelectric materials with remarkable performance were successfully synthesized through suppressing Sn vacancies, followed by electron-doping. Pb alloying notably depressed the Sn vacancies via populating Sn vacancies in SnTe (supported by transmission electron microscopy), and the electrical transports were shifted from p-type to n-type through introducing electrons using I doping. In the n-type SnTe, we found that the electrical conductivity could be enhanced by increased carrier mobility through sharpening conduction bands after alloying Pb, while the lattice thermal conductivity could be reduced via strong phonon scattering after introducing defects by Pb alloying and I doping. Resulting from these enhancements, the n-type Sn0.6Pb0.4Te0.98I0.02 achieves a notably high ZTmax ∼ 0.8 at 573 K and a remarkable ZTave ∼ 0.51 at 300-823 K, which can match many excellent p-type SnTe. This work indicates that n-type SnTe could be experimentally acquired and is a promising candidate for thermoelectric generation, which will stimulate further research on n-type SnTe thermoelectric materials and even devices on the basis of both n- and p-type SnTe legs.

[Breakthroughs in global critical care medicine 2019].

OBJECTIVE: The following trends emerged in international critical care practice in 2019: increasing analysis to phenotypes of sepsis and acute respiratory distress syndrome (ARDS), increasing evidences of early initiating of vasopressors and antibiotics for septic shock, also including the early furosemide stress test for critically ill patients with acute kidney injury (AKI). In addition, there are many significantly important trials with positive results: high dose vitamin C for septic shock, weaning strategy with pressure support ventilation (PSV) mode, tranexamic acid for patients with acute traumatic brain injury, and new monoclonal antibody for Ebola virus disease. And there are also negatives trials as following: individual mechanical ventilation, maximal recruitment open lung ventilation or early neuromuscular blockade for moderate-to-severe ARDS, N95 respirators preventing influenza, flexible family visit program against delirium or early sedation with dexmedetomidine to mechanically ventilated patients, intensive care unit (ICU) diary or nurse-led preventive psychological intervention against posttraumatic stress disorder (PTSD) in patients with mechanical ventilation, recombinant human soluble thrombomodulin (rhsTM) in patients with sepsis-associated coagulopathy, and so on. Further investigations should be focus on the phenotype analysis, by which individualized management fitting for specific pathophysiologic and immune characters for each patient could be clarified.

Epithelial-mesenchymal transition markers screened in a cell-based model and validated in lung adenocarcinoma.

BACKGROUND: Re-capture of the differences between tumor and normal tissues observed at the patient level in cell cultures and animal models is critical for applications of these cancer-related differences. The epithelial-mesenchymal transition (EMT) process is essential for tumor migratory and invasive capabilities. Although plenty of EMT markers are revealed, molecular features during the early stages of EMT are poorly understood. METHODS: A cell-based model to induce lung cell (A549) EMT using conditioned medium of in vitro cancer activated fibroblast (WI38) was established. High-throughput sequencing methods, including RNA-seq and miRNA-seq, and advanced bioinformatics methods were used to explore the transcriptome profile transitions accompanying the progression of EMT. We validated our findings with experimental techniques including transwell and immunofluorescence assay, as well as the TCGA data. RESULTS: We have constructed an in vitro cell model to mimic the EMT in patients. We discovered that several new transcription factors were among the early genes (3 h) to respond to cancer micro-environmental cues which could play critical roles in triggering further EMT signals. The early EMT markers also included genes encoding membrane transporters and blood coagulation function. Three of the nine-examined early EMT hallmark genes, GALNT6, SPARC and HES7, were up-regulated specifically in the early stages of lung adenocarcinoma (LUAD) and confirmed by TCGA patient transcriptome data. In addition, we showed that miR-3613, a regulator of EGFR pathway genes, was constantly repressed during EMT progress and indicative of an epithelial miRNA marker. CONCLUSIONS: The CAF-stimulated EMT cell model may recapture some of the molecular changes during EMT progression in clinical patients. The identified early EMT hallmark genes GALNT6, SPARC and HES7and miR-3613 provide new markers and therapeutic targets for LUAD for the further clinical diagnosis and drug screening.

[Review and forecast of critical care medicine in 2018].

OBJECTIVE: In 2018, a bunch of considerable positive progresses have been presented, including a revised "hour-1 bundle" introduced by international guideline for management of sepsis and septic shock, trans-pulmonary pressure monitoring via esophageal manometry in acute respiratory distress syndrome (ARDS) models, successful trials for new antibiotics, angiotensin II in patients with vasodilatory shock and renal replacement therapy, advanced airway management in out-of-hospital cardiac arrest (OHCA) patients as well cellular immunotherapy for septic shock. But some of investigational trials did not yield expected results. For example, extracorporeal membrane oxygenation (ECMO) therapy for ARDS patients, the strategy of sequencing weaning with early extubation to noninvasive ventilation, prevention of delirium with haloperidol, surrogate decision supported by interprofessional intensive care unit (ICU) team and prophylaxis for gastrointestinal stress ulceration with pantoprazole in ICU. And more importantly, it has been obvious that the voices and evidences gathered by the opponents against guidelines development, compulsory polices of implementing bundled strategy, market position of hydroxyethyl-starch solutions (HES) and the usage of steroid in septic shock have been largely strengthen, highlighting a more divided and controversial situation.

Inhibition of the Hedgehog Signaling Pathway Depresses the Cigarette Smoke-Induced Malignant Transformation of 16HBE Cells on a Microfluidic Chip.

BACKGROUND: The hedgehog signaling system (HHS) plays an important role in the regulation of cell proliferation and differentiation during the embryonic phases. However, little is known about the involvement of HHS in the malignant transformation of cells. This study aimed to detect the role of HHS in the malignant transformation of human bronchial epithelial (16HBE) cells. METHODS: In this study, two microfluidic chips were designed to investigate cigarette smoke extract (CSE)-induced malignant transformation of cells. Chip A contained a concentration gradient generator, while chip B had four cell chambers with a central channel. The 16HBE cells cultured in chip A were used to determine the optimal concentration of CSE for inducing malignant transformation. The 16HBE cells in chip B were cultured with 12.25% CSE (Group A), 12.25% CSE + 5 µmol/L cyclopamine (Group B), or normal complete medium as control for 8 months (Group C), to establish the in vitro lung inflammatory-cancer transformation model. The transformed cells were inoculated into 20 nude mice as cells alone (Group 1) or cells with cyclopamine (Group 2) for tumorigenesis testing. Expression of HHS proteins was detected by Western blot. Data were expressed as mean ± standard deviation. The t-test was used for paired samples, and the difference among groups was analyzed using a one-way analysis of variance. RESULTS: The optimal concentration of CSE was 12.25%. Expression of HHS proteins increased during the process of malignant transformation (Group B vs. Group A, F = 7.65, P < 0.05). After CSE exposure for 8 months, there were significant changes in cellular morphology, which allowed the transformed cells to grow into tumors in 40 days after being inoculated into nude mice. Cyclopamine could effectively depress the expression of HHS proteins (Group C vs. Group B, F = 6.47, P < 0.05) and prevent tumor growth in nude mice (Group 2 vs. Group 1, t = 31.59, P < 0.01). CONCLUSIONS: The activity of HHS is upregulated during the CSE-induced malignant transformation of 16HBE cells. Cyclopamine can effectively depress expression of HHS proteins in vitro and prevent tumor growth of the transformed cells in vivo.

[Nasal surgery and upper airway radiofrequency ablation in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To investigate the efficacy and related factors of nasal surgery combined with upper air way radiofrequency ablation(RFA) for treatment of obstructive sleep apnea hypopnea syndrome (OSAHS) with chronic nasal blockage. METHOD: One hundred and three mild or moderate OSAHS patients with chronic nasal blockage were recruited, all cases had nasal surgery and upper airway RFA. All patients were evaluated by body mass index (BMI), Epworth sleep scale (ESS), snoring scale, and nocturnal polysomnography (PSG). Eighty-nine patients were reevaluated at least 6 months after surgery with the preoperative methods. RESULT: After operation, the apnea and hypopnea index (AHI) decreased from (18.67 +/- 9.48)/h to (9.22 +/- 7.18)/h; the lowest artery oxygen saturation (LSaO2) increased from (0.83 +/- 0.08) to (0.92 +/- 0.06); the Epworth sleep scale(ESS) decreased from (8.74 +/- 5.67) to (5.12 +/- 3.74); the snoring scale decreased from (7.16 +/- 2.85) to (3.56 +/- 2.26), the percentage of time with oxyhemoglobin saturation below 0.90 (CT90) decreased from (18.64 +/- 12.98) to (10.73 +/- 8.29). All of the differences were obvious (P<0.01). Success was defined as a postoperative apnea-hypopnea in dex < 10 events per hour and at least 50% less than the preoperative value. The surgical success rate was 75.3% (67/89). No major perioperative complications occurred. CONCLUSION: Our findings suggest that nasal surgery combined with upper airway RFA can improve snoring and disease-specific quality of life in patients with anatomic na sal obstruction with mild or moderate OSAHS.

[Result of Z-palatoplasty for treating severe obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To investigate the efficacy and related factors of Z-palatoplasty for treating severe obstructive sleep apnea hypopnea syndrome (OSAHS). METHOD: Thirty-two severe OSAHS patients with Friedman II and III oropharyngeal airway had Z-palatoplasty. Twenty-three patients with modified Mallampti Index (MMI) III-IV had coblation tongue channeling (CTC) simultaneously. The patients were followed up for one year post operatively. RESULT: After operation, the apnea and hypopnea index (AHI) decreased from (54.74 +/- 20.38)/h to (22.72 +/- 18.36)/h; the lowest artery oxygen saturation (LSaO2 ) increased from (0.74 +/- 0.08) to (0.85 +/- 0.14); the Epworth sleep scale (ESS) decreased from (12.24 +/- 5.78) to (5.35 +/- 3.62); the percentage of time with oxyhemoglobin saturation below 0.90 (CT90) decreased from (31.48 +/- 20.15) to (15.73 +/- 12.29). All of the differences were statistically significant (P < 0.01). According to related criterion of chinese journal of otorhinolaryngology head and neck surgery in 2009, accumulative excellence rate was 71.9% and accumulative valid rate 84.4%. Six patients had temporary velopharyngeal insufficiency and returned to normal after 3 months. CONCLUSION: Z-palatoplasty is an effective and safe surgical approach for OSAHS patients with Friedman II/III.

[Research on the relationship between obstructive sleep apnea hypopnea syndrome and gastroesophageal reflux].

OBJECTIVE: To study the relationship between obstructive sleep apnea and nocturnal gastroesophageal reflux (GER). METHODS: Seventy-six patients with obstructive sleep apnea hypopnea syndrome (OSAHS) underwent polysomnography (PSG) and nocturnal distal esophageal pH monitoring, to assess the prevalence of GER in OSAHS patients. Among these patients, thirty-two OSAHS patients with GER disease had been operated on. Surgical treatment included uvulopalatopharyngoplasty (UPPP), inferior turbinate reduction, nasal septoplasty et al. After 6 months of surgical treatment, the PSG and pH probe testing were rechecked. The pre and post operative apnea-hypopnea index (AHI), micro-arousal index (MAI), lowest artery oxygen saturation (LSaO2), acidified index of distal esophagus (pHI) and percentage of acid contact time of esophagus were compared. The correlation analysis was also employed. RESULTS: The AHI of 76 OSAHS patients was (38.6 +/- 29.5)/h (average +/- s), GER was present in 48 patients (63.2 %). The pre and post operative AHI, MAI, LSaO2, pHI and percentage of ACT in 32 OSAHS patients associated with GER were (51.2 +/- 23.1)/h and (17.3 +/- 10.3)/h, (38.3 +/- 21.4 )/h and (14.5 +/- 10.0)/h, 0.698 +/- 0.107 and 0.858 +/- 0.076, (12.5 +/- 6.6)/h and (6.3 +/- 4.2)/h, (10.3 +/- 5.2)% and (4.5 +/- 2.9)%. The differences were statistically significant by matching t test (t were 10.95, 7.82, 15.97, 6.12, 7.62 respectively, P < 0.001). There were positive relationships between the reductions of AHI, MAI and the reductions of pHI (r were 0.775, 0.764, P < 0.001). The improved levels of AHI and MAI were correlated with the reduction of the percentage of ACT (r were 0.607, 0.730, P < 0.001). CONCLUSIONS: GER is prevalent in OSAHS patients. Surgical treatment of OSAHS has significant reduction in AHI, MAI as well as marked improvement in the GER, which suggests that nocturnal gastroesophageal reflux is correlated with the disorder of sleep respiration and the sleep disturbances.

[Effects of insulin-like growth factor-1 and insulin on modulating glucose metabolism and functions of lung fibroblasts].

OBJECTIVE: It is recognized that lung fibroblasts (LF) act as a common pathway in the development of fibrosis from alveolitis of whatever etiology. The study was undertaken to identify the modulating effects of insulin-like growth factor-1 (IGF-1) on LF glucose metabolism and functions, to explore possible therapeutic targets through modulating LF for the treatment of pulmonary fibrosis. METHODS: Human embryonic lung (HEL) diploid fibroblast cells were cultured for 24 h with blank control, 100 ng/ml IGF-1, 200 ng/ml IGF-1, 100 ng/ml IGF-1 + 100 ng/ml insulin, 100 ng/ml IGF-1 + 200 ng/ml insulin, 100ng/ml insulin, 200 ng/ml insulin, respectively. The culture supernatants and cell pellets were collected to extract proteins and mRNAs. After quantitated with ultraviolet spectrometer, RT-PCR and Northern blotting were performed to determine the content of glucose transporter-4 (Glut-4), hexokinase II, elastin and collagen-IV. RESULTS: RT-PCR showed that the general mean absorbance ratios of Glut-4 and HK-IImRNA in IGF-1 group were (0.67 +/- 0.25) and (0.60 +/- 0.19), significantly increased as compared with that of control group [(0.61 +/- 0.12), (0.55 +/- 0.19)]; but decreased as compared with that of insulin group [(0.74 +/- 0.26), (0.71 +/- 0.23)]. The expression of elastin, collagen protein in IGF-1 group [(174.3 +/- 4.2), (142.1 +/- 1.0)] were significantly stronger than that of insulin group. CONCLUSIONS: IGF-1 can stimulate LF glucose metabolism, companied with increased expression of elastin and collagen IV in a concentration-dependent manner. IGF-1 can decrease the effect of insulin on LF glucose metabolism, whereas insulin can attenuate the effect of IGF-1 on LF in elastin and collagen expression.

A novel route to polyethylene-polystyrene blends through the fragmentation of porous polystyrene beads supported metallocene in ethylene polymerization.

Polyethylene-polystyrene blends were synthesized by in situ ethylene polymerization with polystyrene porous beads supported metallocene; the influence of fragmenting support beads on the morphology and the mechanical performance of the blends was investigated.