Stimulated Raman scattering is a third-order nonlinear optical effect that is not only effective for wavelength converting laser output, but also for single longitudinal-mode output due to the absence of spatial hole burning. Diamond is a prominent Raman-active medium that has significant potential for linewidth narrowing and wavelength converting lasers at high power levels due to its high thermal conductivity, long Raman frequency shift and wide spectral transmission range. In this work we utilize diamond in a resonantly mode-matched external cavity to achieve cascaded Raman conversion of a 1064 nm laser. By fine-tuning the length of this external cavity, we can obtain narrow linewidth emission at 1240 and 1485 nm. When operating at maximum power, the measured linewidths were more than twofold narrower than the linewidth of the fundamental field. In addition, the noise levels of the Stokes fields are lower than that of the fundamental field throughout the entire noise frequency range, and the intrinsic linewidth of the second Stokes field, which is expressed at the hertz level (~3.6 Hz), is decreased by approximately three orders of magnitude compared to that of the pump. This work represents the first measurement and analysis of the linewidth and noise characteristics of cascaded diamond Raman lasers and, significantly, offers a new means by which high-power, narrow linewidth laser output can be produced from wavelength-converted laser systems.

Recent studies of viscous dissipation mechanisms in impacting droplets have revealed distinct behaviours between the macroscale and nanoscale. However, the transition of these mechanisms from the macroscale to the nanoscale remains unexplored due to limited research at the microscale. This work addresses the gap using the many-body dissipative particle dynamics (MDPD) method. While the MDPD method omits specific atomic details, it retains crucial mesoscopic effects, making it suitable for investigating the impact dynamics at the microscale. Through the analysis of velocity contours within impacting droplets, the research identifies three primary contributors to viscous dissipation during spreading: boundary-layer viscous dissipation from shear flow; rim geometric head loss; and bulk viscous dissipation caused by droplet deformation. This prompts a re-evaluation of viscous dissipation mechanisms at both the macroscale and nanoscale. It reveals that the same three kinds of dissipation are present across all scales, differing only in their relative intensities at each scale. A model of the maximum spreading factor (βmax) incorporating all forms of viscous dissipation without adjustable parameters is developed to substantiate this insight. This model is validated against three distinct datasets representing the macroscale, microscale and nanoscale, encompassing a broad spectrum of Weber numbers, Ohnesorge numbers and contact angles. The satisfactory agreement between the model predictions and the data signifies a breakthrough in establishing a universal βmax model applicable across all scales. This model demonstrates the consistent nature of viscous dissipation mechanisms across different scales and underscores the importance of integrating microscale behaviours to understand macroscale and nanoscale phenomena.

Binary nanodroplet collisions have received increasing attention, whilst the identification of collision outcomes and the viscous dissipation mechanism have remained poorly understood. Using molecular dynamics simulations, this study investigates binary nanodroplet collisions over wide ranges of Weber number (We), Ohnesorge number (Oh) and off-centre distances. Coalescence, stretching separation and shattering are identified; however, bouncing, reflexive separation and rotational separation reported for millimetre-sized collisions are not observed, which is attributed to the enhanced viscous effect caused by the ‘natural’ high-viscosity characteristics of nanodroplets. Intriguingly, as an intermediate outcome, holes form in retracting films at relatively high We, arising from the vibration and thermal fluctuation of the films. Due to the combined effects of inertial, capillary and viscous forces, binary nanodroplet collisions fall into the cross-over regime, so estimating viscous dissipation becomes extremely important for distinguishing outcome boundaries. Based on the criterion that stretching separation is triggered only when the residual off-centre kinetic energy exceeds the surface energy required for separation, the boundary equation between coalescence and stretching separation is established. Here, viscous dissipation is calculated by the extracted flow feature from simulations, showing that the ratio of viscous dissipation to the initial kinetic energy depends only on Oh, not on We. Because of complex viscous dissipation mechanisms, the same boundary equation in the cross-over regime has also not been satisfactorily revealed for macroscale collisions. Therefore, the proposed equation is tested for wide data sources from both macroscale and nanoscale collisions, and satisfying agreement is achieved, demonstrating the universality of the equation.

The role of dietary factors in osteoporotic fractures (OFs) in women is not fully elucidated. We investigated the associations between incidence of OF and dietary calcium, magnesium and soy isoflavone intake in a longitudinal study of 48 584 postmenopausal women. Multivariable Cox regression was applied to derive hazard ratios (HRs) and 95 % confidence intervals (CIs) to evaluate associations between dietary intake, based on the averages of two assessments that took place with a median interval of 2⋅4 years, and fracture risk. The average age of study participants is 61⋅4 years (range 43⋅3–76⋅7 years) at study entry. During a median follow-up of 10⋅1 years, 4⋅3 % participants experienced OF. Compared with daily calcium intake ≤400 mg/d, higher calcium intake (>400 mg/d) was significantly associated with about a 40–50 % reduction of OF risk among women with a calcium/magnesium (Ca/Mg) intake ratio ≥1⋅7. Among women with prior fracture history, high soy isoflavone intake was associated with reduced OF risk; the HR was 0⋅72 (95 % CI 0⋅55, 0⋅93) for the highest (>42⋅0 mg/d) v. lowest (<18⋅7 mg/d) quartile intake. This inverse association was more evident among recently menopausal women (<10 years). No significant association between magnesium intake and OF risk was observed. Our findings provide novel information suggesting that the association of OF risk with dietary calcium intake was modified by Ca/Mg ratio, and soy isoflavone intake was modified by history of fractures and time since menopause. Our findings, if confirmed, can help to guide further dietary intervention strategies for OF prevention.

Oxidation of atomized Al–Mg–Li alloys with compositions ranging from Al0.85Mg0.1Li0.05 to Al0.55Mg0.4Li0.05 (wt%) was examined by thermogravimetry/differential thermal analysis. The results showed that oxidation proceeded in two steps. During the first step, lithium and magnesium were oxidized preferentially and removed from the metallic phase. The other step, during which the remainder of the metallic phase was oxidized, occurred over a wide range of temperature (989–1098 °C). The temperature of the second effect decreased slightly with increasing magnesium content from 10 to 30% in the alloy. For Al0.55Mg0.4Li0.05 alloy, the second exothermic peak occurred at 540 °C, and no exothermic peak was observed at higher temperature. The porous structure formed during the selective oxidation promotes the oxidation of residual Al in the alloy. Al0.55Mg0.4Li0.05 was oxidized completely at 1100 °C, lower than the temperature of other alloys. The thermite reaction experiment of Al0.55Mg0.4Li0.05–Fe2O3 system conducted in Ar showed a reaction temperature of 587 °C, significantly lower than the reaction temperature observed for Al–Fe2O3 system.

Sn–Ag–Cu solder interconnects were made by solidifying the solder balls in a magnetic field and subsequently tested for their electromigration behavior. The orientation of the tin grains was analyzed by electron backscattered diffraction. It was found that the c-axis of Sn grain tended to rotate away from the direction of the magnetic field during solidification, resulting in an enhanced electromigration resistance for the solder joint when the current was applied along the direction of the magnetic field, as evidenced by a smaller electromigration-induced polarity effect in the growth of the interfacial intermetallic compound. Such a reduced polarity-effect of electromigration is shown to agree well with the anisotropy in the diffusivity of the active diffusion species, Cu, in the tetragonal Sn. The difference of free energy change caused by the anisotropy in the magnetic susceptibility of the tetragonal Sn during solidification is suggested to be the main factor for this phenomenon.

The principal–principal (PP) perspective of corporate governance shows that multiple large shareholder (MLS) structure has competing monitoring and entrenchment governance effects. We argue that the dominant effect depends on contest for control among large shareholders and the number of large shareholders involved. Using data from Chinese family listed companies from 2004 to 2007, this study shows inverse U-shaped relationships between contest for control and corporate market value, as measured by Tobin's Q, and between the number of large shareholders and corporate market value. Findings indicate that at low to medium levels of contest for control or number of large shareholders, formal institutions can strengthen MLS structure's monitoring effect and can help this effect last longer. As a whole, the findings extend the institution-based view in the context of family corporate governance by showing that formal institutions can shape the ability of MLS structure to exert governance.

Nanoporous tungsten oxide films were synthesized by an anodic oxidation process in aqueous NaF/HF electrolytes. The tungsten films were deposited by the radio frequency magnetron sputtering method on sapphire substrates, and the anodic oxidation process was conducted in a dual-electrode reaction chamber with graphite electrode. The effects of processing parameters (anodic voltage, time, temperature, and the operation distance) on the morphology and porosity of the synthesized films were investigated experimentally. The samples were characterized by x-ray diffraction and scanning electron microscopy. The results showed that the pore diameter and porosity increased gradually with increasing anodic voltage, whereas the “wall” of the pore was subjected to electric breakdown at 60 V, and the pore diameter and porosity decreased. The pore diameter and porosity showed an early increased and later decreased state as the operation time and distance are increased. The sensitive response in the resistive method is reaction-dominated type and is exhibited as a linear relationship as a function of hydrogen gas concentration. The response toward 500 ppm hydrogen in air is up to 15.1 with a response time of 10 min at 200 °C.

Grain boundary engineering (GBE) has been carried out in nickel-based Alloy 690 with different initial grain sizes. The microstructure evolution during GBE-processing is characterized using electron backscatter diffraction to study the initial grain size effects on the grain boundary network (GBN). The microstructures of the partially recrystallized samples revealed that the GBE-processing is a strain-recrystallization process, during which each grain-cluster is formed by “multiple twinning” starting from a single recrystallization nucleus. Taking into consideration the coincidence site lattices (CSLs) and ∑, which is defined as the reciprocal density of coincidence sites, a high proportion of low-∑ CSL grain boundaries (GBs) and large grain-clusters are found to be the features of GBE-processed GBN. The initial grain size has a combined effect on the low-∑ CSL GBs proportion. A large initial grain size reduces the number of recrystallization nuclei that form, increasing the cluster size, but decreasing twin boundary density. On the other hand, smaller initial grain sizes increase the density of twin boundary after recrystallization, while decreasing grain-cluster size. Neither the grain-cluster size nor the twin boundary density is the sole factor influencing the proportion of low-∑ CSL GBs. The ratio of the grain cluster size over the grain size governs the proportion of low-∑ CSL GBs.

The hot ductility of Ti-bearing steel was studied by theoretical calculation and athermal simulation experiment. Meanwhile, microsegregation and precipitates were analyzed.The results showed that the S, P and O elements were enriched at the grain boundaries,while the hot ductility was deteriorated by inclusions of (Fe, Mn, Si, Al)(S,O) in theinterdendritic region. At a temperature of 1300 °C, large TiN particles have little effecton the hot ductility. In the temperature range from 1000 °C to 900 °C, the Reduction ofArea (R.A) declined rapidly from 81.77%to 31.77%, with the size of particles decreasing from 5 to 20 nm and quantity increasingfrom 1.2 inds/μm2 to 354 inds/μm2,respectively. In the temperature range from 900 °C to 850 °C,R.A decreased from 31.77% to 30.12%with the ferric films gradually thickening. The critical stress, 63.58 MPa, was equal totensile strength at 912 °C. Intergranular fracture occurred easily with higher criticalstress below 912 °C.

Little is known about the association of circulating 25-hydroxyvitamin D (25(OH)D) and blood pressure (BP) parameters, including systolic and diastolic BP, pulse pressure (PP), mean arterial pressure (MAP) and hypertension in non-Western populations that have not yet been exposed to foods fortified with vitamins and seldom use vitamin D supplements. A cross-sectional analysis of plasma 25(OH)D levels in association with BP measures was performed for 1460 participants (1055 women and 405 men, aged 40–74 years) of two large cohort studies in Shanghai. Multivariable linear and logistic regressions were conducted. Overall, the prevalence of vitamin D deficiency was 55·8 % using National Health and Nutrition Examination Survey, USA criteria and 29·9 % using WHO criteria. The median plasma 25(OH)D level in the population was 38·0 nmol/l for men and 33·6 nmol/l for women (P < 0·01) among participants who were not on antihypertensive drugs. Among men, BP parameters (systolic BP, diastolic BP and MAP) were significantly and inversely associated with higher quintiles of 25(OH)D compared with the lowest quintile (Ptrend < 0·05 for all). Vitamin D non-deficient status (WHO criteria) was inversely associated with hypertension (ORadjusted = 0·29; 95 % CI 0·10, 0·82). An inverse association was also found between hypertension and the highest quintile of 25(OH)D (ORadjusted = 0·16; 95 % CI 0·04, 0·65 for ≥ 50·6 nmol/l; Ptrend = 0·02). Among women, no significant associations were found for BP parameters and hypertension. The present study shows that vitamin D deficiency is common among adults in urban China. Circulating 25(OH)D levels were inversely related to the levels of individual BP parameters and hypertension among middle-aged and elderly men but not among women. More research is needed to investigate the potential sex differential associations.

The efficacy of homocysteine (Hcy)-lowering therapy in reducing the risk of CVD among patients with chronic kidney disease (CKD) remains controversial. We performed a meta-analysis to determine whether pooling the data from the few small randomised, controlled trials that address this topic would improve the statistical power of the analysis and resolve some of the inconsistencies in the results. Randomised, controlled clinical trials (RCT) were identified from MEDLINE, EMBASE, www.clinicaltrials.gov, the Cochrane Controlled Clinical Trials Register Database and Nephrology Filters. Independent extraction of articles was performed using predefined data fields. The primary outcome was relative risk (RR) of CVD, CHD, stroke and all-cause mortality for the pooled trials. A stratified analysis was planned, assessing the RR for cardiovascular events between the patients on and not on dialysis. Overall, ten studies met the inclusion criteria. The estimated RR were not significantly different for any outcomes, including CHD (RR 1·00, 95 % CI 0·75, 1·31, P = 0·97), CVD (RR 0·94, 95 % CI 0·84, 1·05, P = 0·30), stroke (RR 0·83, 95 % CI 0·57, 1·19, P = 0·31) and all-cause mortality (RR 1·00, 95 % CI 0·92, 1·09, P = 0·98). In the stratified analysis, the estimated RR were not significantly different for cardiovascular events regardless of dialysis or in combination with vitamin B therapy or the degree of reduction in Hcy levels. Our meta-analysis of RCT supports the conclusion that Hcy-lowering therapy was not associated with a significant decrease in the risk for CVD events, stroke and all-cause mortality among patients with CKD.

A gradient structure was synthesized on the surface of Zr55Al10Ni5Cu30 alloy with high glass-forming ability by laser surface melting (LSM). Along the laser incident direction, the surface remelted alloy exhibits gradient microstructure distributed in the sequence of amorphous structure, nanocrystal- reinforced amorphous matrix composite (transitional layer A), dendrites–amorphous phase composite (transitional layer B), and crystalline phases from the top surface to the substrate. The formation mechanism of this gradient structure is discussed based on the experimental results of the microstructure together with the finite volume simulation of the process of LSM treatment. The friction coefficient of the transitional layer A is ∼2.5 times lower than those of the other layers under the same sliding friction condition, and possible reasons for this phenomenon are discussed in connection with the rolling motion and material transfer mechanism. The transitional layer B exhibits the best wear resistance among all the structures studied here, which is related to the optimized ratio of microhardness to reduced Young’s modulus (H/Er).