Effects of the terms associated with phi(zz) in free surface condition on the attitudes and resistance of different ships

One of approaches for numerical simulation of a ship moving in a still water is based on the composition of double-body flow and wavy flow solved by a boundary element method. There are several terms related to the second order derivative (ϕzz) of double-body flow velocity potential with respect to the vertical coordinate in the free surface conditions. Understanding of the effects of the terms is very limited so far. In many cases, they are just ignored even for ships with a high forward speed, particularly in the cases associated with multihull ships, for which no investigations on their effects have been found. This paper will present a study on the effects of the terms on the numerical prediction of the attitudes and resistance of different ships in various situations, including monohull, catamaran and trimaran with different parameters and at different Froude numbers. The results will demonstrate that the effects of the terms are significant in many cases and that considering this term may lead to the results similar to those obtained by fully nonlinear models at high Froude numbers

Microsite Effects on Physiological Performance of <i>Betula ermanii</i> at and Beyond an Alpine Treeline Site on Changbai Mountain in Northeast China

The alpine treeline demarcates the temperature-limited upper elevational boundary of the tree life form. However, this treeline does not always occur exclusively as a sharp &#8220;line&#8221;, outposts of tree groups (OTG) with a height of at least 3 m are often observed in microsites up to several hundred meters beyond the line of continuous forest on some mountains. This suggests that other factors such as microenvironment may play a significant role in compensating for the alpine tree facing growth-limiting low temperature conditions. To test the microenvironment effects, this study compared the differences in growing conditions (climate and soil properties) and ecophysiological performance of Erman&#8217;s birch (Betula ermanii Cham.) trees growing in a continuous treeline site (CTL, ~1950 m above sea level, a.s.l.) and OTGs (~2050 m a.s.l.) on Changbai Mountain in northeastern China. The results show the average 2-m air temperature for OTG was slightly lower in the non-growing season than which at the CTL (&#8722;10.2 &#176;C &lt; &#8722;8.4 &#176;C), there was no difference in growing season air temperature and soil temperature at 10 cm depth between CTL and OTG. The contents of focal soil nutrients in CTL and OTG were similar. Difference in K and Mn contents between sites were detected in leaves, difference in K, Mn, and Zn in shoots. However, comparing similarity of ecophysiological performances at an individual level, trees at CTL and OTG show no significant difference. Our study reveals that mature trees at the CTL and OTG experience generally similar environmental conditions (climate and soil properties) and exhibit similar overall ecophysiological performance (reflected in carbon reserves and nutrients). This might provide insight into how mature trees might be able to survive in areas higher than the continuous treeline, as well as the importance of microclimatic amelioration provided by protective microsites and the trees themselves

Significantly improvement in formability and ductility of AZ31 Mg alloy by differential temperature rolling

The implementation of asymmetric deformation proves to be an effective approach towards optimizing the basal texture of wrought Mg alloys, ultimately leading to improved plasticity and formability. This work performs differential temperature rolling (DTR) on AZ31 Mg alloy to achieve asymmetric deformation. After the DTR process, the ductility and formability of the RT-200 sample are comparable to the traditional cold rolling and annealing combination process. Combined with the annealing treatment (AT), the fracture elongation and Erichsen value of the RT-200/AT sample are reached 32.4% and 4.49 mm, respectively. The improvement of the ductility and formability is mainly attributed to the texture weakening, which originates from the temperature gradient formed in the DTR process. The gradient temperature field modifies the dynamic recrystallization behavior during the rolling deformation process, as well as the static recrystallization behavior during annealing. The microstructure evolution and the texture weakening mechanism are discussed in detail. The findings can serve as a theoretical reference for the development of high-ductility Mg alloys and for optimizing the continuous hot-rolling process of Mg alloys

A Tomato Putative Metalloprotease SlEGY2 Plays a Positive Role in Thermotolerance

Intramembrane proteases play very important roles in plants, such as chloroplast development, flower morphology, and response to abiotic stress. In this study, a putative metalloprotease gene, homologous to Ethylene-dependent Gravitropism deficient and Yellow-green2 (EGY2) of Arabidopsis, was isolated from tomato (Solanum lycopersicum) plants and named SlEGY2. We found that SlEGY2 was a member of the metalloprotease family M50 which contained conserved motifs HEXXH and NPDG and was localized in the chloroplast. SlEGY2 antisense transgenic tomato plants (AS) have similar hypocotyls phenotype to the Arabidopsis egy2 mutant. Heat (42 °C), PEG, ABA and MeJA treatments can upregulate the expression of SlEGY2. Under heat stress, SlEGY2 AS lines are more sensitive, with more water loss (lower fresh weight), seriously damaged membrane, and ROS accumulation, but lower activities of APX and CAT. In addition, suppression of SlEGY2 decreases the content of chlorophyll and photosynthetic activities, especially photosystem II. These results suggest that SlEGY2 can regulate the thermotolerance of tomatoes by affecting ROS accumulation and photosynthetic activities

Transient Study of Femtosecond Laser–Induced Ge2Sb2Te5 Phase Change Film Morphology

Femtosecond laser-induced crystallization and ablation of Ge2Sb2Te5 (GST) phase change film is investigated by reflectivity pump-probing technology. Below the ablation threshold, the face-centered cubic structure (FCC) state in the central area can be formed, and cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter. The time of surface temperature dropping to the crystallization point needs about 30 ps for 5.86 mJ/cm2 and 82 ps for 7.04 mJ/cm2, respectively. At higher laser fluence, crystallization GST island structures appear in the central ablation region due to the extremely short heating time (100 ps). Furthermore, crystallization rate is faster than the ablation rate of the GST film, which is caused by different reflectivity

High-energy extracorporeal shock wave therapy for nontraumatic osteonecrosis of the femoral head

Abstract Background Nontraumatic osteonecrosis of the femoral head (ONFH) is treated with a series of methods. High-energy extracorporeal shock wave therapy (ESWT) is an option with promising mid-term outcomes. The objective of this study was to determine the long-term outcomes of ESWT for ONFH. Methods Fifty-three hips in 39 consecutive patients were treated with ESWT in our hospital between January 2005 and July 2006. Forty-four hips in 31 patients with stage I–III nontraumatic ONFH, according to the Association Research Circulation Osseous (ARCO) system, were reviewed in the current retrospective study. The visual analog pain scale (VAS), Harris hip score, radiography, and magnetic resonance imaging were used to estimate treatment results. The progression of ONFH was evaluated by imaging examination and clinical outcomes. The results were classified as clinical success (no progression of hip symptoms) and imaging success (no progression of stage or substage on radiography and MRI). Results The mean follow-up duration was 130.6 months (range, 121 to 138 months). The mean VAS decreased from 3.8 before ESWT to 2.2 points at the 10-year follow-up (p < 0.001). The mean Harris hip score improved from 77.4 before ESWT to 86.9 points at the 10-year follow-up. The clinical success rates were 87.5% in ARCO stage I patients, 71.4% in ARCO stage II patients, and 75.0% in ARCO stage III patients. Imaging success was observed in all stage I hips, 64.3% of stage II hips, and 12.5% of stage III hips. Seventeen hips showed progression of the ARCO stage/substage on imaging examination. Eight hips showed femoral head collapse at the 10-year follow-up. Four hips in ARCO stage III and one hip in ARCO stage II were treated with total hip arthroplasty during the follow-up. Three were performed 1 year after ESWT, one at 2 years, and one at 5 years. Conclusions The results of the current study indicated that ESWT is an effective treatment method for nontraumatic ONFH, resulting in pain relief and function restoration, especially for patients with ARCO stage I–II ONFH

A Tomato Putative Metalloprotease SlEGY2 Plays a Positive Role in Thermotolerance

Intramembrane proteases play very important roles in plants, such as chloroplast development, flower morphology, and response to abiotic stress. In this study, a putative metalloprotease gene, homologous to Ethylene-dependent Gravitropism deficient and Yellow-green2 (EGY2) of Arabidopsis, was isolated from tomato (Solanum lycopersicum) plants and named SlEGY2. We found that SlEGY2 was a member of the metalloprotease family M50 which contained conserved motifs HEXXH and NPDG and was localized in the chloroplast. SlEGY2 antisense transgenic tomato plants (AS) have similar hypocotyls phenotype to the Arabidopsis egy2 mutant. Heat (42 &deg;C), PEG, ABA and MeJA treatments can upregulate the expression of SlEGY2. Under heat stress, SlEGY2 AS lines are more sensitive, with more water loss (lower fresh weight), seriously damaged membrane, and ROS accumulation, but lower activities of APX and CAT. In addition, suppression of SlEGY2 decreases the content of chlorophyll and photosynthetic activities, especially photosystem II. These results suggest that SlEGY2 can regulate the thermotolerance of tomatoes by affecting ROS accumulation and photosynthetic activities

Simultaneous improvement of strength and ductility in ZK60 magnesium alloy by constructing the bimodal grain structure

In this study, the microstructure and mechanical properties of the commercial magnesium (Mg) ZK60 alloy were conducted to promote the application of Mg alloys. Scanning electron microscopy, tensile and compression tests, electron back scattering diffraction, transmission electron microscope and visco-plasticity self-consistent methods were employed to analyze the microstructure evolution and the strengthening and toughening mechanisms. By direct extrusion in the as-cast state, a bimodal microstructure was obtained, and the mechanical properties were enhanced. The ZK60 alloy, with a bimodal grain structure, exhibited a good combination of strength and ductility. The tensile yield strength (TYS), ultimate tensile strength (UTS), compressive yield strength (CYS) and fracture elongation (FE) reached 272 MPa, 347 MPa, 289 MPa, and 36.2%, respectively. Compared with the traditional extrusion ZK60 alloy, the increment in TYS, UTS, CYS, and FE was 15 MPa, 31 MPa, 25 MPa and 8.6%, respectively. The formation of the bimodal structure in the ZK60-CE sample is attributed to the combination of the PSN and Zener pinning effects. The improvement in strength is mainly attributed to the residual dislocations in the un-DRXed grains and the good ductility is ascribed to the activation of the non-basal slip. This study provides a low-cost and efficient strategy for the preparation of the bimodal structure by regulating the pre-extrusion microstructure to improve mechanical properties