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Objective. To investigate the clinical effect of nicorandil combined with aspirin in the treatment of myocardial ischemia. Methods. A total of 104 patients with myocardial ischemia were admitted to our hospital from June 2019 to August 2020. These patients were selected as the research objects and randomly divided into two groups: the control group and the observation group. The control group was given asilin, and the observation group was given nicorandil tablets based on the control group. Both groups were given continuous treatment for 3 months. The curative effect, cardiac function indexes, dynamic electrocardiogram, and the occurrence of adverse reactions were observed in the two groups. Results. The total effective rate of the observation group was 96.15% (50/52), which was higher than that of the control group (61.54%, 32/52), and the difference was statistically significant ( P < 0.05 ). After treatment, left ventricular ejection fraction (LVEF) and peak early/late diastolic flow velocity (E/A) were increased ( P < 0.05 ), while peak early diastolic flow velocity to peak mitral annular root movement velocity (E/Ea) was decreased ( P < 0.05 ). After treatment, LVEF and E/A in the observation group were higher than those in the control group, while E/Ea was lower than that in the control group ( P < 0.05 ). The frequency, duration of ST segment, and a total load of myocardial ischemia in the ST segment within 24 h after treatment were decreased compared with those before treatment ( P < 0.05 ). The frequency and duration of ST segment decreased, and the total load of myocardial ischemia in the observation group was lower than those in the control group within 24 h after treatment ( P < 0.05 ). After treatment, the total occurrence of adverse reactions in the observation group was lower than that in the control group ( P < 0.05 ). Conclusion. Nicorandil combined with aspirin in the treatment of patients with myocardial ischemia has a significant effect, which can effectively improve the electrocardiogram and cardiac function indicators of patients and reduce the incidence of adverse reactions and is worthy of clinical application.

Background In-stent restenosis (ISR) is one of major complications after percutaneous coronary intervention (PCI) in patients with coronary artery disease(CAD). The prevention and treatment of ISR is not well established yet. This study explored the correlation and clinical significance of calcium channel blockers(CCB) and ISR . Methods Patients who received coronary angiography(CAG) after PCI in Department of Cardiology, The Third Clinical Medical College of Shanxi Medical University from November 2019 to April 2022 were collected, and the relationship between calcium channel blockers taken by patients before PCI and the occurrence time of in-stent restenosis as well as the severity of restenosis was analyzed. Chi-square test or t test, pearson correlation regression analysis and logistic regression analysis were conducted . Results The in-stent restenosis group (ISR group) and the non-stent restenosis group (no-ISR group) had significant differences in diabetes, previous myocardial infarction history, red blood cell distribution width, fasting blood glucose, ACC/AHA lesion classification, stent maximum diameter, total stent length, and stent expansion pressure (all P

The two-phase flow patterns of ammonia in different scale channels are experimentally investigated in this study. The inner diameters of the tested tubes are 4 mm and 8 mm. The observed flow patterns in the two tubes include slug flow, stratified-wavy flow, annular flow, and annular flow with partial dryout. For both 4 mm and 8 mm tubes, the annular flow gradually expands to a wider vapor quality range with a rise in mass flux and a descent in saturation temperature at the cost of other flow patterns. The comparison of the flow patterns in the two tubes shows that the 8 mm tube has a wider range of annular flow. This is attributed to that the higher dominance of the surface tension force in the 4 mm tube is conductive to the liquid slug to holdup on the channel wall and consequently delay the transition to annular flow. The flow patterns in the two tubes have been compared to the flow pattern maps of Baker, Mandhane et al., and Wojtan et al.. The Wojtan et al. flow pattern map could give a superior prediction for the flow patterns in the 4 mm tube, whereas none of the three existing models accurately predict the flow patterns in the 8 mm tube.

BACKGROUND A retrospective cohort study was conducted to compare the efficacy and safety of direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) in the treatment of patients with left ventricular thrombus (LVT). METHODS Consecutive patients admitted to our institution with LVT between February 2009 and December 2020 and treated with either DOACs or VKAs were considered for inclusion in this study. The outcomes included stroke or systemic embolism (SSE), thrombus resolution, and bleeding events. RESULTS Eighty-seven patients with LVT were identified. Of these, 25 patients were treated with DOACs and 62 patients were treated with VKA. The average follow-up period was 2.37±2.1 years. DOACs were associated with similar incidences of stroke (4.0% vs. 4.8%; P=0.158), systemic embolism (0% vs. 1.6%; P=0.906), SSE (4.0% vs. 6.5%; P=0.657), thrombus resolution (76.0% vs. 74.2%; P=0.057), and blooding events (4.0% vs. 3.2%; P=0.858) as compared to VKAs. In the univariate logistic regression analysis, there was a significant difference between the DOAC and VKA groups in the incidence of SSE when antiplatelets were controlled [odds ratio (OR) =0.34, 95% confidence interval (CI): 0.21, 0.98; P=0.027]. However, in the multivariate analysis, antiplatelets had no significant effect on the outcome (OR =0.41, 95% CI: 0.36, 1.54; P=0.366). CONCLUSIONS DOACs had similar efficacy and safety to VKAs in the treatment of patients with LVT. Randomized controlled trials should be conducted to verify our findings.

Background Lipopolysaccharide (LPS) is one of the main causes of myocardial injury. Dioscin has a protective effect on myocardial injury induced by LPS; however, the biological function and mechanism remain unclear. The purpose of this study was to investigate the effect of dioscin on myocardial injury induced by LPS. Methods The myocardial injury model was constructed through LPS treatment of primary rat cardiomyocytes. Cardiomyocytes were treated with different concentrations of dioscin (50, 100, and 200 ng/mL). MTT was used to detect the activity of cardiomyocytes; flow cytometry and TUNEL assay were used to detect apoptosis; and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). The release of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) was detected according to the kit instructions. The levels of apoptosis-related proteins (Bax, caspase-3, and Bcl 2) and the Nrf2-Keap1 pathway proteins were detected by western blot. Results Dioscin significantly reduced LPS-induced cardiomyocyte injury in neonatal rats in a concentration- and time-dependent manner. Dioscin also significantly inhibited cardiomyocyte inflammation and apoptosis induced by LPS. With the increase of dioscin concentration, reactive oxygen species (ROS) and MDA were downregulated, and SOD and GSH were upregulated. Moreover, dioscin inhibited LPS-induced myocardial injury by inhibiting the Nrf2-Keap1 pathway. Conclusions Our study suggests that dioscin attenuates LPS-induced myocardial injury through oxidative stress-related pathways.

Acute stress relates to high prevalence of anxiety, depression or even sudden death. Although dopaminergic system in amygdala-medial prefrontal cortex (mPFC) circuit is hyper-responsive to stress-induced anxiety, the mechanisms that control anxiety still remains unanswered. Here, the acute restraint stress model(ARS) was established to develop anxiety-like behavior. The D2-dopamine receptor (D2R) availability in amygdala and mPFC was assessed using [18F]-fallypride positron emission tomography(PET) and immunohistochemical assay. We revealed that ARS paradigm was successfully established, as evidenced by elevated plus-maze test(EPM) and increased corticosterone release. Moreover, PET imaging displayed elevated D2R availability in the amygdala and mPFC in ARS as compared to that in the naives. PET imaging combined with immunohistochemical assay confirmed that amygdaloid D2R was significantly implicated in stress-induced anxiety. Our findings delivered valuable insights into neuromechanism of amygdaloid D2R underlying stress-induced anxiety and might have important implications for developing therapeutics for anxiety by targeting amygdaloid D2R.

STUDY QUESTION Is the sperm acrosome membrane-associated protein 1 (SPACA1) gene critical to human globozoospermia? SUMMARY ANSWER The biallelic loss-of-function (variant of SPACA1) causes globozoospermia as a result of acrosome–acroplaxome complex damage. WHAT IS KNOWN ALREADY SPACA1 expression decreases in patients with globozoospermia. Spaca1 gene-disrupted mice have abnormally shaped sperm heads that resemble those of human globozoospermia. STUDY DESIGN, SIZE, DURATION We recruited a consanguineous family with two brothers affected by infertility as a consequence of globozoospermia. The semen analysis data and ART outcomes were collected. Exome sequencing (ES) was used to identify potential pathogenic variants. Protein–protein interaction (PPI) technologies and proteomic analysis were utilized to explore the pathogenic mechanism. PARTICIPANTS/MATERIALS, SETTING, METHODS Two globozoospermic brothers and their consanguineous parents were recruited to identify the potential pathogenic variant through ES. A homozygous nonsense variant in the SPACA1 gene in both brothers inherited from the heterozygous parents was identified. Twenty normal fertile males were recruited as controls. Sperm ultrastructure was observed with transmission electron microscopy. Western blotting was performed to measure SPACA1 expression level in the sperm from the patients. Mass spectrometry (MS) analyses were used to identify differentially expressed proteins and to investigate proteins that interact with SPACA1. Co-immunoprecipitation (co-IP), yeast two-hybrid (Y2H) and immunofluorescence colocalization assays were used to confirm the PPI. MAIN RESULTS AND THE ROLE OF CHANCE A nonsense variant (NM_030960.2: c.53G>A; p. Trp18*) in the SPACA1 gene was identified as the pathogenic variant in a family with globozoospermia. Patient IV:1 and Patient IV:2 had a phenotype very similar to that of Spaca1 gene-disrupted mice. The nonsense variant in SPACA1 led to premature transcriptional termination in the signal peptide, which was confirmed by western blotting. MS-based proteomics analysis showed that eight interactors of SPACA1 were differentially expressed in the patients’ sperm, including actin-like Protein 7A (ACTL7A), an important component of the acrosome–acroplaxome complex. The PPI of SPACA1 and ACTL7A was confirmed via co-IP and Y2H assays. Immunofluorescence showed that SPACA1 and ACTL7A colocalized in mature sperm, revealing that these proteins were coexpressed spatially. LIMITATIONS, REASONS FOR CAUTION Given the rarity of globozoospermia, only two patients from one family harbouring the SPACA1 variant were found. Future studies should evaluate SPACA1 variants in larger cohorts to corroborate this finding. WIDER IMPLICATIONS OF THE FINDINGS This study revealed that the SPACA1 gene was critical for globozoospermia, which expanded the spectrum of causative genes for globozoospermia. This study also provided evidence for ICSI clinical outcomes for patients with SPACA1-deficient globozoospermia, which may guide clinical treatment strategies. Furthermore, this study explored the pathogenesis of globozoospermia caused by SPACA1 deficiency. STUDY FUNDING/COMPETING INTEREST(S) This work was funded by the Precision Medical Research of National Key Research and Development Program (2018YFC1002400), National Natural Science Foundation of China (81873724), and Natural Science Foundation of Shanghai (20ZR1472700). The authors have no conflicts of interest to disclose. TRIAL REGISTRATION NUMBER N/A.

Naphthalenediimides (NDIs) have been extensively studied due to their tunable luminescent properties. However, generally, the monomers or aggregates of non-core substituted NDIs exhibit low fluorescence quantum yields (Φ

With the aim of developing a system with tunable self-assembly of π-conjugated building blocks, an optically active helical polyacetylene bearing amide groups and naphthalene diimide (NDI) derivatives in the side chains is reported. The helical conformation of the polymer backbone and the stacking pattern of the pendant NDIs can be regulated by adding trifluoroacetic acid or specific solvents or anions. In particular, Cl− can induce a dynamic reorganization in molecular arrangement of naphthalenediimides from H-type to J-type aggregates along with turning fluorescence emission on at 515 nm. Consequently, the self-assembly of NDIs is effectively controlled, which can lead to the regulation of the properties of NDI-based materials. To the best of our knowledge, this is the first time that the optically active helical polyacetylene has been applied in the regulation of stacking modes of NDIs. This strategy has shown great potential for anion recognition and the design of stimulus-responsive materials.

Let $m\ge 1$ be an integer and $G$ be a graph with $m$ edges. We say that $G$ has an antimagic orientation if $G$ has an orientation $D$ and a bijection $\tau:A(D)\rightarrow \{1,2,\cdots,m\}$ such that no two vertices in $D$ have the same vertex-sum under $\tau$, where the vertex-sum of a vertex $u$ in $D$ under $\tau$ is the sum of labels of all arcs entering $u$ minus the sum of labels of all arcs leaving $u$. Hefetz, M\"{u}tze and Schwartz [J. Graph Theory, 64: 219-232, 2010] conjectured that every connected graph admits an antimagic orientation. The conjecture was confirmed for certain classes of graphs such as dense graphs, regular graphs, and trees including caterpillars and $k$-ary trees. In this note, we prove that every lobster admits an antimagic orientation., Comment: 1figure

Background: Autophagy plays a non-negligible role in carcinogenesis by maintaining a proper cancer microenvironment to provide nutritional supplements. This study aimed to explore the association between autophagy-related genes (ARGs) and colorectal cancer (CRC). Material and Methods: Public data profiles were downloaded from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases: GSE39582 set. In the TCGA cohort, 7 ARGs were selected to construct the prognostic risk score model for the prognosis of CRC patients. Based on the median value of risk scores, patients were divided into low- and high- risk score groups (p=4.393e−06). And the prognostic value of the model was further validated in the GEO cohort and the pooled cohort. Results: In addition to prognosis, autophagy was also related to malignancy, chemotherapy resistance, as well as immune type of CRC. Furthermore, a nomogram, including the prognostic risk score model and clinical characteristics, was developed for quantifying the overall survival probability of CRC patients. Finally, some drugs/compounds including semagacestat, pentostatin, DNMDP, as well as bexarotene, were predicted as potential drugs for CRC treatment based on CTRP and PRISM database. Conclusion: These would assist CRC patients with improving their prognosis.

To explore the genetic basis of a Chinese pedigree affected with Dyggve-Melchior-Clausen syndrome.Whole exome sequencing and Sanger sequencing were carried out to detect potential pathogenic variants associated with the syndrome. The function of candidate variant was verified by Western blotting.A novel homozygous variant, c.1222delG of the DYM gene was detected in the two affected siblings, for which both parents were heterozygous carriers. The variant has caused replacement of Asp by Met at amino acid 408 and generate a premature stop codon p.Asp408Metfs*10. Western blotting confirmed that the variant can result in degradation of the mutant DYM protein, suggesting that it is a loss of function variant.The homozygous c.1222delG frameshift variant of the DYM probably underlay the Dyggve-Melchior-Clausen syndrome in the two affected siblings. Above findings has enabled clinical diagnosis and genetic counseling for the family.

Fatigue is prevalent in breast cancer patients undergoing postoperative chemotherapy, which seriously affects physical and mental health. The present study aimed to investigate the relevance of fatigue, the self-efficacy of managing chronic disease (SEMCD), and the dual-mode of self-control (DMSC) in patients.Three hundred and seventy six breast cancer patients undergoing postoperative chemotherapy participated in this cross-sectional study. The General Information Questionnaire, Fatigue Scale-14 (FS-14), SEMCD-Scale (SEMCD-S), and DMSC-Scale (DMSC-S) were utilized to survey. Pearson correlation analysis and structural equation modeling were used for the statistical analysis of the correlation between the variables and mediating effects.A total of 372 valid questionnaires (98.94%) were returned. The total fatigue score of FS-14 was (10.84 ± 1.80), the SEMCD-S score (30.05 ± 15.18), and the DMSC-Scale score (73.35 ± 9.49). Furthermore, physical fatigue was negatively correlated with the SEMCD-S and problem solving (r = -0.764 ~ -0.680, P0.01). Mental fatigue correlated positively with poor delay of gratification (r = 0.134, P0.05), and the SEMCD-S was also negatively correlated with the impulsivity, distractibility, and poor delay of gratification dimensions (r =-0.229~-0.130, P0.05). SEMCD correlated positively with problem-solving and future time perspective (r = 0.695~0.790, P0.001). In addition, SEMCD partially mediated the effect between the DMSC and fatigue (β = -0.335, P0.01), with the mediating effect accounting for 51.25%.Through SEMCD measure, it was found that DMSC indirectly influences fatigue levels in breast cancer patients undergoing postoperative chemotherapy.

The low GWP (Global Warming Potential) refrigerant R1234ze(E) is a potential alternative of R134a. This study puts the emphasis on the comparison of the flow boiling pressure drop and heat transfer of R134a and R1234ze(E) in a dimpled flat duct. For the air-conditioning applications, the experiments are conducted at mass flux from 100 to 200 kg m−2 s−1, saturation temperature from 5 to 15 °C, heat flux from 2.5 to 10 kW m−2, and vapor quality from 0.1 to 0.95. The results show that the frictional pressure gradient of R1234ze(E) is 1.10 to 1.27 times that of R134a. The characteristics of the flow boiling heat transfer coefficient of R1234ze(E) are similar to R134a. The increasing flow boiling heat transfer coefficient with vapor quality in the tested range implies the convective evaporation dominates the heat transfer. It is also observed that the flow boiling heat transfer coefficient visibly increases with a rise in mass flux and decreases with the saturation temperature increment due to the increase in vapor to liquid density ratio. The enhancement effect of heat flux on the flow boiling heat transfer shows up at the highest value of 10 kW m−2 only. The heat transfer coefficient ratio of R1234ze(E) to R134a increases from 0.89 to 1.20 with an increase in vapor quality. The comparison of frictional pressure gradient and heat transfer characteristics between R1234ze(E) and R134a has been discussed from the viewpoint of fluid properties.

The effect of an applied electric field and Mg2+ doping on the formation of calcium carbonate scale in circulating cooling water was investigated by using a home-made experimental device, which can simulate the formation of scale in a local power plant. The results show that high-voltage electrostatic fields and magnesium ions can inhibit scale growth in circulating cooling water. When the magnesium ion concentration is 4 mmol/L, the scale inhibition effect is the best under the action of the electric field (6 kV), and its scale inhibition rate can reach 44.56%. Meanwhile, some phenomena are explained and confirmed by the results of first principle calculations. The calculated shear modulus of aragonite is greater than that of calcite. This might explain why aragonite adheres more easily to the heat exchange surface. This is in good agreement with experimental results. Calcite has better anti-scaling properties than aragonite. The crystal structure after physical water treatment is blunt, and the untreated crystal structure is sharp.

The carrier phase (CP) technique based on the global positioning system is a widely applied spatial tool for precise time and frequency transfer. However, the traditional CP technique considers the receiver clock offset to be a white noise stochastic process, which introduces unknown errors into the model and thereby compromises time and frequency transfer performance. To improve the performance of the traditional CP technique, an atomic clock modelling CP time transfer (AMCP) method is proposed. A first-order, one variable grey model is employed to establish the receiver clock offset forecast model for the formation of prior information. The results show that the AMCP approach, which uses an atomic clock correlation between nearby epochs, outperformed the traditional CP technique. The noise level of the AMCP solution was improved by 7.7% for the NTSC–PT11 link, and the improvement for the other three time links were all ∼2.0%. The average improvement of the absolute jumps in the day-boundary discontinuities was ∼13.1%. Additionally, the frequency stability of the AMCP solution was improved, and the mean improvement was 10.2, 12.0, 10.7, and 8.3% for TLT4–PT11, USN9–PT11, WAB2–PT11, and NTSC–PT11, respectively.

The elevation interpolation of coal seam floors is an indispensable geological work to the production of coal mines. In this study, an improved radial basis function (RBF) interpolation method was proposed to support the interpolation of a feature with the local anisotropy characteristic. First, the local anisotropy of the floor elevation of coal seams was characterized by using the method of geographically weighted regression. The interpolation was realized by fitting residuals between actual values and geographically weighted regression values with RBF. Second, an adaptive selection of interpolation reference points was realized. The Delaunay triangulation network was used to define the relationship of natural proximity between the point to be interpolated and reference points and it ensured the relatively uniform distribution of reference points around the point to be interpolated. Based on this, the appropriate selection radius of reference points for the study area was obtained by cross validation. Third, the influence of faults was considered in the interpolation, and the value of reference points were augmented or deducted according to the attributes of faults concerned. Finally, the method was applied in the mining region 302 of Yanzishan Coal Mine in North China. The proposed method was illustrated to be effective with better robustness and interpolation accuracy compared with some typically used methods.

The hypoxic microenvironment of cryptorchidism is an important factor to induce the impairment of the structure and function of Sertoli cells and thus lead to spermatogenesis loss or tumorigenesis. Dihydrotestosterone (DHT), as a potent nonaromatizable 5α-reduced androgen, has both positive and negative effect on pathological fibrosis process. However, it is still unknown whether DHT can regulate hypoxia-induced fibrosis of Sertoli cells. Herein, in this study, we evaluate the DHT level, two 5α-reductase isoforms, 5α-red1 and 5α-red2, as well as HIF-1α expression pattern in canine cryptorchidism and contralateral normal testis. Results showed that the abdominal testes presented low DHT levels and 5α-red1 and 5α-red2 expression, while significantly higher HIF-1α expression and ECM production compared with the scrotum. Moreover, we established a hypoxia-induced fibrosis model in canine Sertoli cells induced by cobalt chloride (CoCl

The total reciprocal edge-eccentricity of a graph G is defined as $$\xi ^{ee}(G)=\sum _{u\in V_G}\frac{d_G(u)}{\varepsilon _G(u)}$$, where $$d_G(u)$$ is the degree of u and $$\varepsilon _G(u)$$ is the eccentricity of u. In this paper, we first characterize the unique graph with the maximum total reciprocal edge-eccentricity among all graphs with a given number of cut vertices. Then we determine the k-connected bipartite graphs of order n with diameter d having the maximum total reciprocal edge-eccentricity. Finally, we identify the unique tree with the minimum total reciprocal edge-eccentricity among the n-vertex trees with given degree sequence.

The experimental satellite of the third generation BeiDou navigation satellite system (BDS-3e) is a significant step towards expanding the current regional BDS-2 into a global satellite navigation system. These satellites are equipped with new atomic clocks and the application of time and frequency transfer is therefore important. In this study, carrier phase observations from BDS-3e and BDS-2 satellites were employed in time and frequency transfer. Experiments with two schemes were designed to assess the time and frequency transfer performance. BDS-3e increased the number of available satellites, and the corresponding time dilution of precision (TDOP) was improved. Therefore, the accuracy of receiver clock offset is improved, and the noise level of time links with BDS-3e is also improved compared to using only the BDS-2 constellation. The range was 4.2% for the CEDU-KAT1 time link. However, because fewer satellites are available and the corresponding accuracy of satellite tracking geometry is low for the HOB2-KAT1 time link, the above-mentioned improvement was not apparent. In terms of the frequency stability, the CEDU-KAT1 time link using the BDS-3 solution showed an improvement of approximately 12.3% compared to using only the BDS-2 solution when the averaging time intervals were within 1000 s.

The asymmetrical planar mechanical behaviors of an extruded AZ31 sheet possessing bimodal texture distribution (a strong c-axis∥normal direction (ND) texture component accompanied with a sub-strong tilted c-axis∥transverse direction (TD) texture component) were investigated. Rolling process was carried on such an asymmetrically textured sheet to regulate the microstructure and texture, and thus to try to modify the poor room temperature mechanical properties. The results indicated that the plastic deformation mechanism activated in the c-axis∥TD textured grains during rolling was sensitive to the rolling paths. When the rolling direction was perpendicular to the tilted direction of the texture component, prismatic slip and extension twinning would be activated in the c-axis∥TD oriented matrix, and their activities readily varied with the pass reduction. Whereas when the rolling direction was parallel to the tilted direction of the texture component, only extension twinning based on consuming the tilted texture component was permissible. As a result, the microstructure, texture, rollability and the final modified mechanical properties of the sheet were strongly dependent on the rolling paths, and their evolutions during various rolling processes were investigated in detail. This study could give instructional meaning on property modification of Mg alloy sheets with similar asymmetrical texture distribution.

The flow boiling characteristics of ammonia/miscible oil mixture are experimentally studied. Experiments are conducted in an 8 mm tube at oil concentration from 0 to 5.78%, mass flux from 51 to 99.5 kg m −2 s −1 , heat fluxes of 9 and 21 kW m −2 , and temperature from −5.5 to −5 °C. The heat transfer is basically deteriorated with the influence of miscible oil. Specifically, the effect of miscible oil is small in low vapor quality region, and with a rise in vapor quality, the oil causes significant heat transfer deterioration at smaller mass flux. Meanwhile, Gungor and Winterton (1986) correlation can predict 98.5% of the experimental data within ±30% error band. In addition, the experimental results reveal that the pressure drop are insensitive to the oil concentration.

High-performance frequency standards are affected by power-law noises and characterized by structure functions (i.e., variances). These variances with specified averaging time quantify the frequency stability of the oscillator. To improve the stability estimated from the measured data and extend its maximum averaging time, a method called "StONA" (oscillator noise analysis under stochastic restrictions) is proposed based on convex optimization techniques. StONA also measures the intensity coefficients of noise processes as a by-product of extending averaging time. To test the method against real data, we recompute the distribution regions of total and Hadamard variances estimated from 14 days of satellite clock data and predict the stability of extended averaging time. The recomputed and predicted variances are inconsistent with the ones estimated from 168 days of data and have smaller uncertainty than those estimated from 84 days of time deviations.

A jet pump with an asymmetrical channel can induce a time-averaged pressure drop in oscillatory flow, which can effectively suppress Gedeon streaming in looped thermoacoustic engines. In this work, the flow characteristics and time-averaged pressure drop caused by a jet pump in turbulent oscillatory flow are investigated through numerical simulation. Through the analysis of the dimensionless governing equations, the emphasis is put on the effects of Womersley number and maximum acoustic Reynolds number on the performance of the jet pump. Meanwhile, the steady flow resistance coefficients are also measured numerically. The results indicate that the oscillatory flow resistance coefficients are relatively insensitive to Womersley number when it is less than 46. Moreover, the oscillatory flow resistance coefficients agree well with the steady state flow results, which validate the quasi-static assumption in turbulent oscillatory flow. However, further increasing Womersley number will lead to a reduction in the time-averaged pressure drop. The simulation method and results, as well as the hydrodynamic mechanism beneath the results, are presented and discussed in detail.

A series of experiments are conducted to investigate the two-phase pressure drop of ammonia in horizontal small diameter tube. The experiments are performed at saturation temperatures of −15.8–4.6 °C, and the mass flux range is from 20 to 100 kg m−2 s−1. This paper analyzes the influence mechanisms of vapor quality, mass flux, saturation temperature, and tube diameter on the two-phase frictional pressure gradient in detail. Meanwhile, several correlations are compared with all the experimental data and the results show that the Muller-Steinhagen and Heck (1986) correlation gives the best agreement. With the analysis of the major forces for ammonia two-phase flow under the tested experimental conditions, the Reynolds number and Bond number are introduced to modify the Muller-Steinhagen and Heck (1986) correlation. Lastly, a modified correlation is developed with the mean absolute deviation of only 13.5%, and 89.2% of the data are within the ± 30% error band. In addition, the modified correlation is evaluated based on a complied database which contains 951 experimental data points from 11 published literatures.

In this article, a series of experiments was conducted to investigate the flow boiling heat transfer and pressure drop characteristics of ammonia in a 4 mm horizontal plain tube. The experiments were performed for heat fluxes at 9 and 21 kW m−2 K−1, mass flux from 50 to 100 kg m−2 s−1, and saturation temperature from −15.8 to 5 °C. The experimental results show that with the increase of heat flux, the heat transfer coefficient increases. Meanwhile, it also increases with a rise in mass flux in the low vapor quality region, whereas reversed situation can take place in the high vapor quality region when the saturation temperature is decreased. The saturation temperature has little effect on the heat transfer coefficient in the low vapor quality region, however at higher mass fluxes, the heat transfer coefficient can decrease with decreasing saturation temperature in the high vapor quality region. The comparisons of the experimental data with existing correlations for flow boiling heat transfer coefficient show that Gungor and Winterton correlation can give good agreement with mean absolute deviation of 19.6% even though it is developed for turbulent flow. The adiabatic two-phase frictional pressure gradient increases with the increase of vapor quality and mass flux, while decreases with the increase of saturation temperature. The comparisons with existing correlations for two-phase frictional pressure gradient indicate that Muller-Steinhagen and Heck correlation can predict the experimental data well with mean absolute deviation of 16.1% and 93.4% of the data is within the ±30% error band.

Large ring laser gyros are regarded as suitable sensors for precise monitoring of the Earth’s rotation. Their long-term stability, high sensitivity, and mechanical properties suggest themselves for potential terrestrial deployment, such as Universal Time (UT1), Length of Days (LOD), Geophysics, etc. This inertial technology based on Sagnac interferometers measure any non-reciprocal effect which gives rise to a difference of optical path lengths between forward-propagating laser beams and the counter-propagating within the cavity. Differing from their cousins used in navigation, large ring lasers is usually a heterolithic optical cavity composed of four independent reflector components s to avoid employing large whole Zerodur. Comparing with other UT1 measuring technologies, large ring lasers has characteristics of higher resolution and good real-time, which is highly complementary to VLBI observation technology. In order to meet the measurement of UT1 error less than 1ms/day to coordinate with VLBI, the resolution of ultra-stable laser gyros must be better than 10e-13rad/s. The geometric stability of heterolithic ring cavity is demanded stringently. We simulated the intrinsic relationship between geometric deformation and scale factor of optical cavity. The influence of temperature on geometric deformation has been analyzed and the temperature compensation strategy is proposed. The temperature field distribution of the laser gyro is approximately evaluated by measuring the temperature network of some specific points.