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Nano-Ag sintering is a promising die attach technology for the wide bandgap semiconductive power devices, while the high cost of nanosilver limits industrial application. Reducing bondline thickness (BLT) is effective for cost saving but its effects on reliability has been rarely studied, especially at high temperature operation. In this work, an organic-free nanostructured silver film was prepared by pulsed laser deposition (PLD) for various BLT joints. The effect of BLT (3.5-60 μm) on the high temperature reliability of die-attached modules was systematically investigated. The results indicated that with the increase of BLT, the shear strength and power cycling number of joints both increased. The optimal BLT ranged in 25-50 μm considering both reliability and cost. It was very interesting to find that the connection ratio along the BLT direction existed two valleys at the die-bondline and DBC-bondline interfaces, which clearly corresponded to the crack propagating in power cycling test.

Future electronic skin systems require stretchable conductors and low-temperature integrations of external components, which remains challenging for traditional metal films. Herein, a bioinspired design concept is reported to endow metal films with 200% stretchability as well as room-temperature integration capability with diverse components. It is revealed that by controllable defects implantation, distinctive venation-mimicking cracking modes can be induced in strained metal films, leading to profound stretchability regulation. An intriguing exponential-to-linear transition of the film electromechanical performance is observed, which is elucidated by a unified model covering the essence of all modes. Combined with room-temperature integration capability, an integrated electronic skin is constructed with metal films serving as stretchable electrodes, diverse sensors, and "tapes" to attach subcomponents, showing prospects in helping disabled people. This one-step, defects implantation strategy is applicable to common metals without special substrate treatments, which enables fascinating ultra-stretchable metal film conductors with low-temperature integration capability to spark more sophisticated flexible electronic systems. This article is protected by copyright. All rights reserved.

Ag-Cu bimetallic nanoparticles, combining the advantages of both Ag and Cu, are a promising material for power electronic packaging. In this work, a supersaturated Ag-7.3 wt % Cu alloy nanoparticle film was developed by using pulsed laser deposition. Unlike Cu nanoparticles, the supersaturated Ag-Cu alloy nanoparticles can conduct bonding in air without the assistance of a reduction agent. The shear strength was >20 MPa when the bonding temperature reached 300 °C, which was above the die shear standard (MIL-STD-883 K, 7.8 MPa) and compatible with the typical die attach process. The Cu separating behavior was accompanied by the bonding process at 250-400 °C, which was discussed systematically. Neck formation was delayed to about 250 °C because of the hindering effect of the thin oxide shell of the Ag-Cu alloy. The necking networks provide volume diffusion paths despite the growth of surface oxide, resulting in compact densification. The bondline under the SiC die consisted of a porous Ag-Cu alloy matrix with a dispersed secondary phase of Cu2O/CuO, which is supposed to have improved electrochemical migration resistance.

Silver (Ag)-based materials have shown great application potential in the oxygen reduction reaction (ORR) and hydrogen peroxide (H2O2) detection. The porous structures of Ag have attracted a lot of research interest due to their large specific surface area and high electrochemical activity. In this work, nanoporous Ag structures composed of nano-sized particles were prepared by a one-step pulsed laser deposition (PLD) under controlled background gas pressure. The porous PLD-Ag showed a high ORR performance (Eonset: 1.007 V vs. RHE, E1/2: 0.863 V vs. RHE), high sensitivity (613.1 μA cm-2 mM-1 at -0.2 V vs. SCE) and selectivity for H2O2 detection. The PLD technique provided a new, yet universal approach to producing high-performance, metal-based electrochemical electrodes.

Bonding a large-area die by Ag nanoparticle paste sintering faces a lot of challenges, and the voids/cracks caused by residual organics of the paste are some of the obstacles. The organic burnt out during the sintering process and degassing of the residue organics during service cause significant concerns. In this study, organic-free Ag nanoparticle material has been developed by pulsed laser deposition technology. Oweing to being organic-free, no void, crack and delamination were observed in the sintered Ag layer of die-attachment, and the large-area die-attachment could be carried out by a simple sintering profile at low temperature. The die shear test indicated that the bonding strength was superior to the standard. Porosity and densification of the sintered Ag layer could be controlled by sintering profiles, including the processing pressure, temperature and time.

To investigate the relation of blood arsenic concentration (BAC) with clinical effect and safety of arsenic-containing Qinghuang Powder (青黄散, QHP) in patients with myelodysplastic syndrome (MDS). Totally 163 patients with MDS were orally treated with QHP for 2 courses of treatment, 3 months as 1 course. The BACs of patients were detected by atomic fluorescence spectrophotometry at 1, 3, and 6 months during the treatment, and the effective rate, hematological improvement and safety in patients after treatment with QHP were analyzed. After 2 courses of treatment, the total effective rate was 89.6% (146/163), with 31.3% (51/163) of hematological improvement and 58.3% (95/163) of stable disease. The hemoglobin increased from 73.48 ± 19.30 g/L to 80.39 ± 26.56 g/L (P 0.05). Among 46 patients previously depended on blood transfusion, 28.3% (13/46) completely got rid of blood transfusion and 21.7% (10/46) reduced the volume of blood transfusion by more than 50% after treatment. The BACs were significantly increased in patients treated for 1 month with 32.17 ± 18.04 μ g/L (P 0.05). The adverse reactions of digestive tract during the treatment were mild abdominal pain and diarrhea in 14 cases (8.6%), and no patients discontinued the treatment. The BACs of patients with gastrointestinal adverse reactions were significantly lower than those without gastrointestinal adverse reactions (22.39 ± 10.38 vs. 37.89 ± 11.84, μ g/L, P

Metallic materials based sensors have shown potential applications in the detections of strain, temperature, pressure, and surface-enhanced Raman scattering (SERS). However, most metal-based sensors can only detect a single stimulus. In this work, we designed a multifunctional silver sensing platform for simultaneous strain sensing and SERS sensing. The silver nanoporous structures were facilely deposited by a pulsed laser deposition technique. The microstructure of silver layer could be readily controlled by adjusting deposition parameters, which greatly influenced the sensitivity and sensing range of strain detection. The interface of a sensor could be controlled to achieve a high sensitivity of strain sensing. Different trace substances were detected by the sensing platform through SERS. This sensing platform also had good antibacterial properties, which are advantageous in wearable electronics.

Traditional Chinese Medicine (TCM) is a practical medicine based on thousands of years of medical practice in China. Arsenic dispensing powder (ADP) has been used as a treatment for MDS patients with a superior efficacy on anemia at Xiyuan Hospital of China Academy of Chinese Medical Sciences. In this study, we retrospectively analyzed MDS patients that received ADP treatment in the past 9 years and confirmed that ADP improves patients’ anemia and prolongs overall survival in intermediate-risk MDS patients. Then, we used the MDS transgenic mice model and cell line to explore the drug mechanism. In normal and MDS cells, ADP does not show cellular toxicity but promotes differentiation. In mouse MDS models, we observed that ADP showed significant efficacy on promoting erythropoiesis. In the BFU-E and CFU-E assays, ADP could promote erythropoiesis not only in normal clones but also in MDS clones. Mechanistically, we found that ADP could downregulate HIF1A in MDS clones through upregulation of VHL, P53 and MDM2, which is involved in two parallel pathways to downregulate HIF1A. We also confirmed that ADP upregulates GATA factors in normal clones. Thus, our clinical and experimental studies indicate that ADP is a promising drug to promote erythropoiesis in both MDS and normal clones with a superior outcome than current regular therapies. ADP promotes erythropoiesis in myelodysplastic syndromes via downregulation of HIF1A and upregulation of GATA factors.

To investigate the relationship between gene mutations and response to Compound Qinghuang Powder (复方青黄散, CQHP) in patients with myelodysplastic syndrome (MDS). Forty-three MDS patients were genotyped by ultra-deep targeted sequencing and the clinical data of patients were collected and the relationship between them was analyzed. Up to 41.86% of patients harbored genet mutations, in most cases with more than one mutation. The most common mutations were in SF3B1, U2AF1, ASXL1, and DNMT3A. After treatment with CQHP, about 88.00% of patients no longer required blood transfusion, or needed half of prior transfusions. CQHP is an effective treatment for patients with MDS, especially those with gene mutations in SF3B1, DNMT3A, U2AF1, and/or ASXL1.

Thermal stress caused by the coefficients of thermal expansion (CTE) mismatch of materials is the main failure mechanism in power electronic packaging. High junction temperature (Tj) would induce larger thermal stress and accelerate failing process. In this paper, two packaging strategies to reduce thermal stress of power module for high-temperature operation were presented based on organic-free sintered Ag bonding and wireless packaging structuring: reduce elastic modulus of sintered Ag layer by changing sintering parameters; and reduce the CTE mismatch by changing the ribbon material. Finite-element analysis (FEA) simulations confirmed that these strategies can effectively reduce the maximum and average thermal stress in power electronics packaging. Furthermore, by combining these two strategies, high-temperature power cycling test indicated that the wireless packaging with Cu30Mo70 ribbon and 5 MPa sintering pressure exhibited excellent durability and reliability in the temperature swing at the junction (ΔTj∆Tj) over 150 K.

Decreasing the interconnecting temperature is essential for 3D and heterogeneous device integrations, which play indispensable roles in the coming era of "more than Moore". Although nanomaterials exhibit a decreased onset temperature for interconnecting, such an effect is always deeply impaired because of organic additives in practical integrations. Meanwhile, current organic-free integration strategies suffer from roughness and contaminants at the bonding interface. Herein, a novel bilayer nanoarchitecture simultaneously overcomes the drawbacks of organics and is highly tolerant to interfacial morphology, which exhibits universal applicability for device-level integrations at even room temperature, with the overall performance outperforming most counterparts reported. This nanoarchitecture features a loose nanoparticle layer with unprecedented deformability for interfacial gap-filling, and a compact one providing firm bonding with the component surface. The two distinct nanoparticle layers cooperatively enhance the interconnecting performance by 73-357%. Apart from the absence of organics, the internal abundant lattice disorders profoundly accelerate the interconnecting process, which is supported by experiments and molecular dynamics simulation. This nanoarchitecture is successfully demonstrated in diversified applications including paper-based light-emitting diodes, Cu-Cu micro-bonding, and SiC power modules. The strategy proposed here can open a new paradigm for device integrations and provide a fresh understanding on interconnecting mechanisms.

Silver electrochemical migration causing short-circuit could be mitigated by Ag-Pd alloy. The conventional mechanical mixed Ag and Pd nanoparticles requires high alloying temperature as high as 850 °C. In this work, Ag20Pd nanoalloy film is prepared using pulsed laser deposition under room temperature as die attach material. After low temperature bonding at 300 °C, the bondline keeps in Ag20Pd alloyed state with a shear strength of 23.5 MPa (higher than MIL-STD-883 K, 7.8 MPa). The Ag20Pd nanoalloy exhibits superior resistance to Ag ionic migration with short-circuit time tripled than pure Ag sintered layer. A Ag-rich layer appears on the surface of Ag-Pd nanoalloy, although the Ag-Pd is the typical isomorphous alloy system. Molecular dynamics simulation reveals that Ag atoms (214.0 kJ/mol) diffuse easier than that of Pd atoms (234.6 kJ/mol) on the nanoalloy surface layer, while showing similar mobility for inner nanoalloy. The Ag-rich layer consisting of dynamic exchanging atoms has a prewetting effect and contributes to the neck formation among nanoparticles. This work sheds light on the sintering mechanism of Ag-Pd nanoalloy, and it is confirmed that Ag-Pd nanoalloy is promising for low temperature bonding in terms of the high reliability power electronic.

Objective. To establish the clinical safe and effective methods of arsenic-containing compound-Qinghuang Powder (compound-QHP) in the treatment of myelodysplastic syndrome (MDS). Methods. 200 patients with MDS were treated with compound-QHP (daily dose of 0.1 g realgar). The blood arsenic concentrations (BACs) were detected by atomic fluorescence spectrophotometry (HF-AFS). After treatment for 1 month, the patients were randomly divided into group A and group B when the BACs were less than 20 μg/L. Daily dose of realgar was maintained in group A and it was increased to that when the BACs were more than 20 μg/L in group B. The BAC and clinical efficacy and safety in two groups were compared at the end of the treatment with compound-QHP. Results. The average BAC of group B was significantly higher than that of group A (P<0.01). The rates of hematology improvement and reduced transfusion were significantly higher in group B than in group A (P<0.05). The HGB, ANC, and PLT significantly increased in group B after treatment (P>0.05). Conclusions. Monitoring the BAC and adjusting the daily dose of realgar to increase the effective BAC and then improving efficacy without increasing the clinical toxicity are the clinical safe and effective methods in the treatment of MDS.

In this work, an organic-free silver nanostructured film (SNF) was applied to bond SiC chips and ceramic substrates, which was fabricated by ultrafast pulsed laser deposition (PLD). Unlike the commercial nano silver paste which contains 10%–30% organics, the bonding temperature of SNF could be reduced to only 180 °C, with the average shear strength of 18 MPa, ~3 times higher than the standard MIL-STD-883 K. The average shear strength of sintered joints reached 40 MPa when sintering temperature increased to 250 °C. The shear strength of joints was strongly dependent on their microstructure, especially the porosity and pore distribution of sintered layer. It can be tuned by size distribution and aggregation mode of particles in deposited SNF. Sintering mechanisms and strategies for obtaining appropriate mechanical property and porosity were discussed.

To evaluate the potential of Chlorococcum pamirum for producing biodiesel, the effects of nitrogen, phosphate, initial cell concentrations and NaCl on lipid accumulation and growth were studied. The highest specific growth rate (mu(max)), biomass productivity and lipid content achieved was 1.888 d (1), 350.1 mg L (1) day (1), and 64.9%, respectively. Under nitrogen-deficient condition, the cells accumulated lipids faster at low initial cell concentration. Additional NaCl to nitrogen-deficient media accelerated the lipid accumulation. When adding 10 g L (1) NaCl to nitrogen-deficient media, the lipid content and productivity of cells cultured outdoors with high initial cell concentration increased from 38.2% and 153 mg L (1) day (1) to 54.3% and 192 mg L (1) day (1) respectively. Moreover, NaCl enhanced the saturated fatty acids content from 56.40% to 73.41% of total fatty acids. The results show that C. pamirum is a promising organism for biofuel production. (C) 2014 Elsevier Ltd. All rights reserved.

Oil-in-water (O/W) emulsions have been used as a delivery system to protect conjugated linoleic acid (CLA), a polyunsaturated fatty acid, from oxidation. Conventional gum arabic (GA) and two matured gum arabic samples (EM2 and EM10) were used as emulsifiers to prepare CLA-in-water emulsions. The emulsions have optimal physical and chemical stability at gum concentrations of 5% for all three gums. Emulsions with higher gum concentrations are more susceptible to lipid oxidation. This is attributed to reduced physical stability at higher gum concentrations because of the coalescence and depletion-induced flocculation of the emulsion droplets. The prooxidants iron and copper intrinsically contained in the gums could also contribute to this instability. Among the three gums, EM10 provides the most effective protection for CLA both physically and chemically, because of its superior interfacial properties over GA and EM2.

The edible blue-green alga, Nostoc sphaeroides Kutzing, is able to form microcolonies and spherical macrocolonies. It has been used as a potent herbal medicine and dietary supplement for centuries because of its nutraceutical and pharmacological benefits. However, limited information is available on the development of the spherical macrocolonies and the environmental factors that affect their structure. This report described the morphogenesis of N. sphaeroides from single trichomes to macrocolonies. During the process, most structural features of macrocolonies of various sizes were dense maculas, rings, the compact core and the formation of liquid core; and the. laments within the macrocolonies showed different lengths and arrays depending on the sizes of macrocolonies. Meanwhile temperature and light intensity also strongly affected the internal structure of macrocolonies. As microcolonies further increased in size to form 30 mm macrocolonies, the colonies differentiated into distinct outer, middle and inner layers. The. laments of the outer layer showed higher maximum photosynthetic rates, higher light saturation point, and higher photosynthetic effciency than those of the inner layer; whereas the. laments of the inner layer had a higher content of chlorophyll a and phycobiliproteins than those of the outer layer. The results obtained in this study were important for the mass cultivation of N. sphaeroides as a nutraceutical product. (c) 2008 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.

Nostoc sphaeroides Kutzing was cultivated in paddlewheel-driven raceway ponds and the growth kinetics of 1-2 mm and 3-4 mm colonies of N. sphaeroides was studied. The biomass productivities in 2.5 m(2) raceway ponds inoculated with 1-2 mm and 3-4 mm colonies were 5.2 and 0.25 g dry wt m(-2) stop d(-1), respectively. Furthermore, differently sized colonies showed different relative water content, total soluble carbohydrates, chlorophyll a content and density of filaments. This is the first report on mass culture of N. sphaeroides under outdoor conditions.

GaAs(100) and InP(100) samples were cleaved in UHV to give (110) surface in order to investigate their energy band changes using high resolution x-ray photoelectron spectroscopy (XPS) measurement. It was revealed that the surface band of a heavy doped n-GaAs(110) sample bent upward 0.4 eV and that of a heavy doped p-GaAs(110) bent downward 0.3 eV to the midgap after cleavage whereas the surface band of a heavy doped n-InP(110) sample bent upward 0.1 eV and that of a heavy doped p-InP(110) bent downward 0.65 eV to the midgap. As for the causes of band bending, we excluded the possibility of surface charging, X-Ray radiation damage and the effect of residual gas in UHV during XPS measurement. The experimental results strongly suggest that the band bending process was caused by the surface lattice relaxation after cleavage.

To evaluate the potential of the green agla Chlorella zofingiensis as a feedstock for biodiesel production, the effects of nitrogen and phosphate on lipid accumulation and growth of C. zofingiensis were studied. The maximum specific growth rate (mu(max)) reached 2.15 day(-1) when the concentration of NaNO3 and K2HPO4 center dot 3H(2)O was 1.0 g L-1 and 0.01 g L-1 respectively. The lipid contents of C. zofingiensis grown in media deficient of nitrogen (65.1%) or phosphate (44.7%) were both higher than that obtained from cells grown in full medium (33.5%). The highest lipid productivity (87.1 mg L-1 day(-1)) was also obtained from cells grown in nitrogen deficient media, indicating nitrogen deficiency was more effective than phosphate deficiency for inducing lipid accumulation in C. zofingiensis. In addition, the feasibility of cultivating the alga in 60 L flat plate photobioreactors and 10 L bottles outdoors for biodiesel was also tested. It was found that C. zofingiensis could adapt to fluctuating temperatures and irradiance of outdoors and the highest mu(max) and lipid productivity could reach 0.362 day(-1) and 26.6 mg L-1 day(-1) outdoors, respectively. The lipid production potential of C. zofingiensis is projected to be 31.1 kg ha(-1) day(-1) in outdoor culture. These results suggested that C. zofingiensis is a promising organism for feedstock production of biofuel and can be used in scaled up culture outdoors. (c) 2012, The Society for Biotechnology, Japan. All rights reserved.

Culturing microalgae using natural sunlight is an effective way to reduce the cost of microalgae-based biodiesel production. In order to evaluate the feasibility of culturing Chlorella zofingiensis outdoors for biodiesel production, effects of nitrogen limitation and initial cell concentration on growth and lipid accumulation of this alga were investigated in 60 L flat plate photobioreactors outdoors. The highest mu(max) and biomass productivity obtained was 0.994 day(-1) and 58.4 mg L(-1) day(-1), respectively. The lipid content was much higher (54.5% of dry weight) under nitrogen limiting condition than under nitrogen sufficient condition (27.3%). With the increasing initial cell concentrations, the lipid contents declined, while lipid concentrations and productivities increased. The highest lipid content, lipid concentration, and lipid productivity obtained was 54.5%, 536 mg L(-1) and 22.3 mg L(-1) day(-1), respectively. This study demonstrated that it was possible to culture C. zofingiensis under outdoor conditions for producing biodiesel feedstock. (C) 2011 Elsevier Ltd. All rights reserved.