scholarly journals Fragmentation of lead-free and lead-based hunting rifle bullets under real life hunting conditions in Germany

AMBIO ◽  
2019 ◽  
Vol 48 (9) ◽  
pp. 1056-1064 ◽  
Author(s):  
Anna Lena Trinogga ◽  
Alexandre Courtiol ◽  
Oliver Krone
Keyword(s):  
Real Life ◽  
Lead Free ◽  
Rifle Bullets

Lead-Free Metal Halide Perovskite Nanocrystals for Photocatalysis in Water

2019 ◽  
Author(s):  
Subhajit Bhattacharjee ◽  
Sonu Pratap Chaudhary ◽  
Sayan Bhattacharyya
Keyword(s):  
Charge Carrier ◽  
Wide Spectrum ◽  
Real Life ◽  
Metal Halide ◽  
Lead Free ◽  
Water Medium ◽  
Type I ◽  
Type Ii ◽  
Perovskite Layer ◽  
Halide Perovskites

<p>Metal halide perovskites with high absorption coefficient, direct generation of free charge carriers, excellent ambipolar charge carrier transport properties, point-defect tolerance, compositional versatility and solution processability are potentially transforming the photovoltaics and optoelectronics industries. However their limited ambient stability, particularly those of iodide perovskites, obscures their use as photocatalysts especially in aqueous medium. In an unprecedented approach we have exploited the photo-absorption property of the less toxic lead-free Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9 </sub>(X = Br, I) nanocrystals (NCs) to catalyse the degradation of water pollutant organic dye, methylene blue (MB) in presence of visible light at room temperature. After providing a proof-of-concept with bromide perovskites in isopropanol, the perovskites are employed as photocatalysts in water medium by designing perovskite/Ag<sub>2</sub>S and perovskite/TiO<sub>2 </sub>composite systems, with Type I (or quasi Type II) and Type II alignments, respectively. Ag<sub>2</sub>S and TiO<sub>2</sub> coatings decelerate penetration of water into the perovskite layer while facilitating charge carrier extraction. With a minimal NC loading, Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>/Ag<sub>2</sub>S degrades ~90% MB within an hour. Our approach has the potential to unravel the photocatalytic properties of metal halide perovskites for a wide spectrum of real-life applications. </p>

Effects of Shear Cycling on the Mechanical Properties of SAC and SAC+X Lead Free Solder Joints

2019 ◽  
Author(s):  
Mohd Aminul Hoque ◽  
Md Mahmudur Chowdhury ◽  
Sa’d Hamasha ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Real Life ◽  
Material Behavior ◽  
Lead Free ◽  
Lead Free Solder ◽  
Cyclic Shear ◽  
Mechanical Cycling ◽  
Free Solder

Abstract Solder joint reliability is a chief concern in electronic assemblies. Electronic packages consist of various materials, each having their own Coefficient of Thermal Expansion (CTE). When assembled packages experience high temperature gradients and thermal cycles, a mismatch in the CTE values brings about cyclic shear strains in the solder joints, which can ultimately lead to failure. Thus, it is important to understand the effects of shear cycling on the damage accumulated in solder joints. Previous studies conducted on the effect of mechanical cycling on the material behavior of lead free solders have been performed on bulk samples subjected to tension and compression. Our goal in this study was to determine the evolution of the mechanical properties of doped lead free solder joints when subjected to mechanical shear cycling. Experiments conducted on actual solder joints would help us gain a better understanding on the real life effects of shear cycling. The test specimens consisted of a 3 × 3 array of nine solder joints of approximately 0.75 mm diameter. With the aid of specially designed test fixtures, the specimens were gripped and then subjected to mechanical cycling in the shear using an Instron Micromechanical tester. Testing was performed on both SAC305 and SACX (SAC+Bi) solder joints. The joints were cycled for certain durations, and a nanoindentation system was used to measure the evolution of the mechanical properties (elastic modulus, hardness, creep rate) as a function of the number of shear cycles.

Lead-Free Metal Halide Perovskite Nanocrystals for Photocatalysis in Water

2019 ◽  
Author(s):  
Subhajit Bhattacharjee ◽  
Sonu Pratap Chaudhary ◽  
Sayan Bhattacharyya
Keyword(s):  
Charge Carrier ◽  
Wide Spectrum ◽  
Real Life ◽  
Metal Halide ◽  
Lead Free ◽  
Water Medium ◽  
Type I ◽  
Type Ii ◽  
Perovskite Layer ◽  
Halide Perovskites

<p>Metal halide perovskites with high absorption coefficient, direct generation of free charge carriers, excellent ambipolar charge carrier transport properties, point-defect tolerance, compositional versatility and solution processability are potentially transforming the photovoltaics and optoelectronics industries. However their limited ambient stability, particularly those of iodide perovskites, obscures their use as photocatalysts especially in aqueous medium. In an unprecedented approach we have exploited the photo-absorption property of the less toxic lead-free Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9 </sub>(X = Br, I) nanocrystals (NCs) to catalyse the degradation of water pollutant organic dye, methylene blue (MB) in presence of visible light at room temperature. After providing a proof-of-concept with bromide perovskites in isopropanol, the perovskites are employed as photocatalysts in water medium by designing perovskite/Ag<sub>2</sub>S and perovskite/TiO<sub>2 </sub>composite systems, with Type I (or quasi Type II) and Type II alignments, respectively. Ag<sub>2</sub>S and TiO<sub>2</sub> coatings decelerate penetration of water into the perovskite layer while facilitating charge carrier extraction. With a minimal NC loading, Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>/Ag<sub>2</sub>S degrades ~90% MB within an hour. Our approach has the potential to unravel the photocatalytic properties of metal halide perovskites for a wide spectrum of real-life applications. </p>

Enabling MSL-1 Capability for QFN and Other Design Leadframe Packages

2010 ◽  
Vol 2010 (1) ◽  
pp. 000137-000142
Author(s):  
Dan Hart ◽  
John Ganjei ◽  
Nilesh Kapadia
Keyword(s):  
Chemical Treatment ◽  
Real Life ◽  
Acoustic Microscopy ◽  
Lead Free ◽  
Vapor Pressures ◽  
Copper Surfaces ◽  
Surface Mount ◽  
Final Yield ◽  
Negative Side Effects ◽  
Component Manufacturing

As the conversion of the electronics industry to lead free soldering materials continues some unexpected negative side effects of higher lead free reflow temperatures have occurred. Defects such as delamination or “popcorning” in surface mount components have increased significantly since lead free soldering has become mainstream. Popcorning is a defect that manifests itself as a fracture between the epoxy based encapsulant and the metal, usually copper alloy, leadframe components used to form a surface mount component. This fracture occurs when moisture in the package volatilizes during reflow processes and forces its way through the encapsulation material and leadframe interface. Peak reflow temperatures for leaded solder typically run around 215° – 225° C but due to the higher melting point of lead free solders, they require peak reflow temperatures of 240° to 260° C range. This 30° increase in reflow temperatures can have a significant effect on the electronic devices and any resident moisture in the component The keys to popcorning, or delamination, defect reduction is twofold. The first objective is to enhance the bond between the encapsulant and the copper leadframe materials to form a stronger bond that can resist the vapor pressures induced during reflow. The other objective is to provide a superior bond between the leadframe and encapsulant thus minimizing moisture ingress. New chemical treatment processes have been developed that pre-treat the copper surfaces of the leadframe and significantly enhance the bond between the encapsulant material and the metal leadframe. The chemical treatment process results in micro-roughening of the copper surfaces and at the same time depositing a thermally robust film that enhances the chemical bond between the epoxy encapsulant material and the copper. This paper examines the possible issues and the real life successes when comparing standard component manufacturing methods to those that incorporate the aforementioned chemical adhesion promotion process. Components are assembled using both processes and final performance is tested using MLS-1 conditioning protocols, acoustic microscopy analysis (SAM), and final yield improvement.

A peek in the micro-sized world: a review of design principles, engineering tools, and applications of engineered microbial community

2020 ◽  
Vol 48 (2) ◽  
pp. 399-409
Author(s):  
Baizhen Gao ◽  
Rushant Sabnis ◽  
Tommaso Costantini ◽  
Robert Jinkerson ◽  
Qing Sun
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Environmental Remediation ◽  
Real Life ◽  
Design Principles ◽  
Microbial Interactions ◽  
Potential Applications ◽  
New Gene ◽  
Global Biogeochemical Cycles ◽  
Synthetic Microbial Communities

Microbial communities drive diverse processes that impact nearly everything on this planet, from global biogeochemical cycles to human health. Harnessing the power of these microorganisms could provide solutions to many of the challenges that face society. However, naturally occurring microbial communities are not optimized for anthropogenic use. An emerging area of research is focusing on engineering synthetic microbial communities to carry out predefined functions. Microbial community engineers are applying design principles like top-down and bottom-up approaches to create synthetic microbial communities having a myriad of real-life applications in health care, disease prevention, and environmental remediation. Multiple genetic engineering tools and delivery approaches can be used to ‘knock-in' new gene functions into microbial communities. A systematic study of the microbial interactions, community assembling principles, and engineering tools are necessary for us to understand the microbial community and to better utilize them. Continued analysis and effort are required to further the current and potential applications of synthetic microbial communities.

The Speech-Language Pathologist in the Public Schools: Preparation for Real Life Practices From the Perspective of a Speech-Language Pathology Program Coordinator

2010 ◽  
Vol 11 (2) ◽  
pp. 60-65
Author(s):  
Francine Wenhardt
Keyword(s):  
Public Schools ◽  
School Setting ◽  
Real Life ◽  
Effective School ◽  
Program Coordinator ◽  
Educational Preparation ◽  
The Public ◽  
Speech Language Pathologist ◽  
New Graduate ◽  
Language Pathology

Abstract The speech-language pathologist (SLP) working in the public schools has a wide variety of tasks. Educational preparation is not all that is needed to be an effective school-based SLP. As a SLP currently working in the capacity of a program coordinator, the author describes the skills required to fulfill the job requirements and responsibilities of the SLP in the school setting and advises the new graduate regarding the interview process and beginning a career in the public schools.

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