Mapping of Long-Wavelength Phonon Contribution in the Thermal Transport of Alloyed Semiconductor Superlattices.

The mapping of long-wavelength phonons is important to understand and manipulate the thermal transport in multilayered structures, but it remains a long-standing challenge due to the collective behaviors of phonons. In this study, an experimental demonstration of mapping the long-wavelength phonons in an alloyed Al0.1Ga0.9As/Al0.9Ga0.1As superlattice system is reported. Multiple strategies to filter out the short- to mid-wavelength phonons are used. The phonon mean-free-path-dependent thermal transport properties directly demonstrate both the suppression effect of the ErAs nanoislands and the contribution of long-wavelength phonons. The contribution from phonons with mean free path longer than 1 µm is clearly demonstrated. A model based on the Boltzmann transport equation is proposed to calculate and describe the thermal transport properties, which depicts a clear physical picture of the transport mechanisms. This method can be extended to map different wavelength phonons and become a universal strategy to explore their thermal transport in various application scenarios.

Optically Controlled Nano-Transducers Based on Cleaved Superlattices for Monitoring Gigahertz Surface Acoustic Vibrations.

Surface acoustic waves (SAWs) convey energy at subwavelength depths along surfaces. Using interdigital transducers (IDTs) and opto-acousto-optic transducers (OAOTs), researchers have harnessed coherent SAWs with nanosecond periods and micrometer localization depth for various applications. These applications include the sensing of small amount of materials deposited on surfaces, assessing surface roughness and defects, signal processing, light manipulation, charge carrier and exciton transportation, and the study of fundamental interactions with thermal phonons, photons, magnons, and more. However, the utilization of cutting-edge OAOTs produced through surface nanopatterning techniques has set the upper limit for coherent SAW frequencies below 100 GHz, constrained by factors such as the quality and pitch of the surface nanopattern, not to mention the electronic bandwidth limitations of the IDTs. In this context, unconventional optically controlled nanotransducers based on cleaved superlattices (SLs) are here presented as an alternative solution. To demonstrate their viability, we conducted proof-of-concept experiments using ultrafast lasers in a pump-probe configuration on SLs made of alternating AlxGa1-xAs and AlyGa1-yAs layers with approximately 70 nm periodicity and cleaved along their growth direction to produce a periodic nanostructured surface. The acoustic vibrations, generated and detected by laser beams incident on the cleaved surface, span a range from 40 to 70 GHz, corresponding to the generalized surface Rayleigh mode and bulk modes within the dispersion relation. This exploration shows that, in addition to SAWs, cleaved SLs offer the potential to observe surface-skimming longitudinal and transverse acoustic waves at GHz frequencies. This proof-of-concept demonstration below 100 GHz in nanoacoustics using such an unconventional platform might be useful for realizing sub-THz to THz coherent surface acoustic vibrations in the future, as SLs can be epitaxially grown with atomic-scale layer width and quality.

Strata behaviour and stability control of the automatic roadway formation by roof cutting below a fault influenced longwall goaf.

Automatic roadway formation by roof cutting (ARFRC) is a novel nonpillar mining method that has the potential to dramatically increase coal recovery while reducing the roadway excavation ratio. When this method is used below a fault influenced longwall goaf, large deformation and support failure occur in the roadway using conventional roadway formation techniques. In the study, the ARFRC method was tested in the Liliu mining area of China, which is characterized by goafs and faults. Field experiments and numerical modelling were used to evaluate the stability of the roadway by analysing the behaviour of overlying strata under the special geological condition. The results show that the surroundings of the formed roadway were greatly affected by the fault and the overlying coal pillar in the goaf. In the fault- and coal pillar-affected areas, the loads on the roadway roof increased by approximately 35% and 15%, respectively. According to the strata behaviour of the formed roadway surroundings, targeted support techniques for ARFRC were proposed, and the reliability of the support techniques were demonstrated by field practice.

Prediction of Nonlinear Micro-Milling Force with a Novel Minimum Uncut Chip Thickness Model.

The minimum uncut chip thickness (MUCT), dividing the cutting zone into the shear region and the ploughing region, has a strong nonlinear effect on the cutting force of micro-milling. Determining the MUCT value is fundamental in order to predict the micro-milling force. In this study, based on the assumption that the normal shear force and the normal ploughing force are equivalent at the MUCT point, a novel analytical MUCT model considering the comprehensive effect of shear stress, friction angle, ploughing coefficient and cutting-edge radius is constructed to determine the MUCT. Nonlinear piecewise cutting force coefficient functions with the novel MUCT as the break point are constructed to represent the distribution of the shear/ploughing force under the effect of the minimum uncut chip thickness. By integrating the cutting force coefficient function, the nonlinear micro-milling force is predicted. Theoretical analysis shows that the nonlinear cutting force coefficient function embedded with the novel MUCT is absolutely integrable, making the micro-milling force model more stable and accurate than the conventional models. Moreover, by considering different factors in the MUCT model, the proposed micro-milling force model is more flexible than the traditional models. Micro-milling experiments under different cutting conditions have verified the efficiency and improvement of the proposed micro-milling force model.

Generation of shrimp waste-based dispersant for oil spill response.

In this study, shrimp waste was enzymatically hydrolyzed to generate a green dispersant and the product was tested for crude oil dispersion in seawater. The hydrolysis process was first optimized based on the dispersant effectiveness (DE) of the product. The functional properties of the product were identified including stability, critical micelle concentration, and emulsification activity. Water was confirmed as a good solvent for dispersant generation when compared with three chemical solvents. The effects of salinity, mixing energy, and temperature on the dispersion of the Alaska North Slope (ANS) crude oil were examined. Microtox acute toxicity test was also conducted to evaluate the toxicity of the produced dispersant. In addition, DE of the product on three different types of crude oil, including ANS crude oil, Prudhoe Bay crude oil (PBC), and Arabian Light crude oil (ALC) was compared with that of the Corexit 9500, respectively. The research output could lead to a promising green solution to the oil spill problem and might result in many other environmental applications.

Sputum mucin 1 is increased during the acute phase of chronic obstructive pulmonary disease exacerbation.

BACKGROUND: Mucin 1 (MUC1) is a membrane tethered protein on airway epithelial cells. This protein is upregulated and plays an important anti-inflammatory role during acute lung inflammation. However, the relationship between sputum MUC1 level and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is unknown. METHODS: The levels of MUC1, IL-8, and TNF-α in induced sputum from 78 COPD patients were assessed by ELISA. The association between COPD exacerbation and MUC1 fragment levels was analyzed. An acute airway inflammation mouse model was established by intranasal LPS inhalation. The expression of Muc1 in lung and the levels of Muc1, TNF-α and KC in BAL fluid from mice were determined with western blotting and ELISA, respectively. RESULTS: Higher levels of MUC1 membrane-tethered (CT) and extracellular (EC) fragments, cytokines TNF-α and IL-8, more leucocyte and neutrophil counts were found in sputum from COPD patients in acute than in remission phase. Linear regression analysis confirmed that the level of sputum MUC1 CT fragment is positively correlated with sputum neutrophil number and patients' age; whereas the sputum EC fragment level is correlated inversely with FEV1/FVC value and positively with patients' age. Inhalation of lipopolysaccharide (LPS) induced acute lung inflammation in mice which exhibited increased levels of Muc1 CT fragment in lung and only Muc1 EC fragment increase in BAL fluid. CONCLUSIONS: Unlike pure bacterial induced lung inflammation, both sputum MUC1 CT and EC fragments are increased during acute exacerbation of COPD. The clinical benefits from measuring the changes of various sputum MUC1 fragments in AECOPD need to be elucidated in future studies.

Modeling and optimization of Newfoundland shrimp waste hydrolysis for microbial growth using response surface methodology and artificial neural networks.

The hydrolyzed protein derived from seafood waste is regarded as a premium and low-cost nitrogen source for microbial growth. In this study, optimization of enzymatic shrimp waste hydrolyzing process was investigated. The degree of hydrolysis (DH) with four processing variables including enzyme/substrate ratio (E/S), hydrolysis time, initial pH value and temperature, were monitored. The DH values were used for response surface methodology (RSM) optimization through central composite design (CCD) and for training artificial neural network (ANN) to make a process prediction. Results indicated that the optimum levels of variables are: E/S ratio at 1.64%, hydrolysis time at 3.59h, initial pH at 9 and temperature at 52.57°C. Hydrocarbon-degrading bacteria Bacillus subtilis N3-1P was cultivated using different DHs of hydrolysate. The associated growth curves were generated. The research output facilitated effective shrimp waste utilization.

Bone morphogenetic protein 4 inhibits liposaccharide-induced inflammation in the airway.

Bone morphogenetic protein 4 (BMP4) is a multifunctional growth factor that belongs to the TGF-ß superfamily. The role of BMP4 in lung diseases is not fully understood. Here, we demonstrate that BMP4 was upregulated in lungs undergoing lipopolysaccharide (LPS)-induced inflammation, and in airway epithelial cells treated with LPS or TNF-α. BMP4 mutant (BMP4(+/-) ) mice presented with more severe lung inflammation in response to LPS or Pseudomonas aeruginosa, and lower bacterial load compared with that in BMP4(+/+) mice. Knockdown of BMP4 by siRNA increased LPS and TNF-α-induced IL-8 expression in 16HBE human airway epithelial cells and in primary human bronchial epithelial cells. Similarly, peritoneal macrophages from BMP4(+/-) mice produced greater levels of TNF-α and keratinocyte chemoattractant (KC) upon LPS treatment compared with cells from BMP4(+/+) mice. Administration of exogenous BMP4 attenuated the upregulation of TNF-α, IL-8, or KC induced by LPS and/or TNF-α in airway epithelial cells, and peritoneal macrophages. Finally, partial deficiency of BMP4 in BMP4(+/-) mice protected the animals from restrictive lung function reduction upon chronic LPS exposure. These results indicate that BMP4 plays an important anti-inflammatory role, controlling the strength and facilitating the resolution of acute lung inflammation; yet, BMP4 also contributes to lung function impairment during chronic lung inflammation.

Tanshinone IIA inhibits lipopolysaccharide-induced MUC1 overexpression in alveolar epithelial cells.

The anti-inflammatory function of tanshinone IIA (TIIA), an active natural compound from Chinese herbal medicine Danshen, has been well recognized, and therefore TIIA has been widely used to treat various inflammatory conditions associated with cardiac and lung diseases. Mucin 1 (Muc1) plays important anti-inflammatory roles in resolution of acute lung inflammation. In this study, we investigated the effects of TIIA on LPS-induced acute lung inflammation, as well as its relationship to Muc1 expression in mouse lung and MUC1 in human alveolar epithelial cells. TIIA pretreatment significantly inhibited LPS-induced pulmonary inflammation in both Muc1 wild-type (Muc1(+/+)) and knockout (Muc1(-/-)) mice, as manifested by reduced neutrophil infiltration and reduced TNF-α and keratinocyte chemoattractant levels in bronchoalveolar lavage fluid. The inhibitory effects of TIIA on airway inflammation were associated with reduced expression of Muc1 in Muc1(+/+) mouse lung. Moreover, pretreatment with TIIA significantly inhibited LPS-induced MUC1 expression and TNF-α release in A549 alveolar epithelial cells. TNF-α upregulated MUC1 mRNA and protein expression in A549 cells, which was inhibited by pretreatment with TIIA. The LPS-induced MUC1 expression was blocked when A549 cells were transfected with siRNA targeting for TNF-α receptor 1. Furthermore, TIIA inhibited LPS-induced nuclear translocation of NF-κB and upregulation of Toll-like receptor 4 in A549 cells. Taken together, these results demonstrate that TIIA suppressed LPS-induced acute lung inflammation regardless of the presence of Muc1, and TIIA inhibited LPS- and TNF-α-induced MUC1/Muc1 expression in airway epithelial cells, suggesting that MUC1/Muc1 does not account for the mechanisms of the anti-inflammatory effects of TIIA in the airway.

Determination of lead by square wave anodic stripping voltammetry using an electrochemical sensor.

A novel electrochemical assay for lead (Pb(2+)) detection was developed in this study, involving the use of screen-printed electrodes (SPEs). The sensor was used with selected supporting electrolytes in conjunction with square wave anodic stripping voltammetry (ASV) to study the redox characteristics of lead. Good response currents were obtained using a supporting electrolyte comprising acetate buffer pH 5.0 with 0.5 mol L(-1) NH4Cl. Without a deposition process, the anodic peaks for higher lead concentrations (ranging from 0.7 to 10 mg L(-1)) were sharp and symmetrical on the bare electrode surface. Optimal ASV conditions were obtained with a well-defined stripping peak for 200 µL deposition solution volumes, a deposition potential of -1.2 V for Ag/AgCl, and a deposition time of either 300 or 400 s. Under optimal conditions, a calibration curve ranging from 6.25 to 500 µg L(-1) was obtained for lead determination. Furthermore, the performance of a Hg-free sensor for Pb(2+) determination was compared with that of a Hg-coated electrode, and the detection limits were approximately 0.9 - 1.5 µg L(-1).

Successful thrombolysis in postoperative patients with acute massive pulmonary embolism.

PURPOSE: The standard medical management for patients with acute massive pulmonary embolism (MPE) is systemic thrombolysis. However, it is generally thought that recent surgeries are a contraindication to thrombolytic therapy. In this study, we evaluated the efficacy and safety of systemic thrombolysis for postoperative patients with acute MPE and assessed the risk of bleeding. METHODS: A retrospective review was performed on 21 postoperative patients with MPE in a timeframe of five years (from 2005 to 2010). The criteria for study inclusion were postoperative patients who received systemic thrombolysis for confirmed acute MPE within three weeks after surgery. RESULTS: Seventeen postoperative patients, including men (12) and women (five) aged 53±16 (range 23-71) years, were treated with systemic thrombolysis. Significant haemodynamic improvement (shock index<0.9) was observed in 16 of 17 cases (94%). The remaining patient (6%) died of cardiac arrest within 24h. No major bleeding complication was observed. Sixteen patients survived and remained stable for 34±16 (range 11-52) days until hospital discharge. CONCLUSION: Recent surgery is not an absolute contraindication to systemic thrombolysis. Further, to obtain a successful outcome, it is crucial to exclude patients who have received neurosurgical operations or those with other contraindications to thrombolytic therapy.

Inhibitory effects of a specific phage-displayed peptide on high peritoneal metastasis of gastric cancer.

Peritoneal dissemination in gastric cancer is the most frequent cause of the noncurative resection and recurrence after curative resection. We, therefore, evaluated the feasibility of a peptide, which was obtained by screening a random phage display library, in the treatment of peritoneal metastases of gastric cancer. In this study, a novel cell line, GC9811-P, with a high potential peritoneal metastasis of gastric cancer derived from its parental cell line, GC9811, was established. Using a phage display library, we isolated a specific peptide that selectively bound to GC9811-P cells rather than its parental GC9811cells. The isolated phage-displaying peptide, SMSIASPYIALE (named peptide PIII), was obtained after four rounds of selection, showing a tendency to preferentially bind to GC9811-P cells compared with a panel of other gastric cancer cell lines, and preferentially accumulate in peritoneal metastasis tumor tissue in comparison with control organs, peritoneum, liver, pancreas, spleen, lung, and kidney. Further study showed that synthetic peptide PIII could significantly inhibit adhesive and invasional ability of GC9811-P cells and could effectively block the corresponding phage binding to the GC9811-P cells, whereas, exposure of the cells to various concentrations of peptide PIII showed no obvious cell growth inhibition. Furthermore, a highly reproducible animal experimental model of gastric cancer with peritoneal dissemination was established in nude mice by injecting a suspension of the cell line into the gastric wall of nude mice. Animals intraperitoneally treated with peptide PIII in this model or another animal model of gastric cancer with peritoneal dissemination established using MKN45 cells showed suppressed tumor metastasis to peritoneum and significantly prolonged survival. In conclusion, the selected peptide PIII was a biologically active peptide and could effectively inhibit peritoneal dissemination of gastric cancer.

Phage display selection of peptides that inhibit metastasis ability of gastric cancer cells with high liver-metastatic potential.

Organ-specific metastasis is an important character of cancer cells. Cancer cells that can metastasize to a special organ were thought to have different proteins in cell membrane, which might have potential utility as diagnostic markers and therapeutic targets. In the present work, based on high liver-metastatic gastric cancer cells, XGC9811-L, a screening approach with phage displayed peptide library, was successfully used to isolate 8-mer peptide ligands binding to the target cells. The phage20 had the highest binding efficiency to XGC9811-L cells, which also displayed remarkable cell specificity. Peptide20 that was displayed on phage20 could suppress the motility and invasion of XGC9811-L significantly. The adhesive ability of XGC9811-L to collagen IV was also inhibited by peptide20. Furthermore, phage20 could significantly reduce the incidence of liver metastasis of gastric cancer transplanted into nude mice and was also beneficial for the reduction the number of metastatic nodules in the liver. In conclusion, the phage display is an effective method to screen for the new molecules associated with organ-specific metastasis. The selected peptide20 can reverse the liver metastasis behavior of the gastric cancer cells.

[Screening and identification of phage-displayed polypeptides specifically binding to human gastric cancer with high metastatic potential to peritoneum].

OBJECTIVE: By means of phage-display technique, to screen polypeptides that specifically bind to human gastric cancer with high metastatic potential to peritoneum. METHODS: Two human gastric cancer cell lines were used: GC9811-P with high metastatic potential to peritoneum and its wild type parental GC9811, to carry out subtractive screening with a phage display-12 peptide library. RESULTS: After three rounds of screening, 40 phage clones bond to GC9811-P cells were randomly selected. When injected into the peritoneal cavity of nude mice, 6 of the 40 clones did not bind to mouse peritoneum as examined by immunohistochemical staining. They were considered to be capable of binding specifically to GC9811-P cells. Sequence analysis revealed two different exogenous peptides: TLNINRLILPRT and SMSI(X)SPYI(XXX). CONCLUSION: Two peptides have been obtained that specifically bind to a gastric cancer cell variant GC9811-P, which easily disseminates to the peritoneum. Whether or not they could block GC9811-P metastasis to peritoneum in vivo remains to be determined.