Corner fracture

Metaphyseal corner fractures are highly associated with non-accidental trauma and it is important not to confuse certain normal metaphyseal variants with these injuries. The normal metaphyseal variants include metaphyseal step-off, beak or spur, and proximal tibial cortical irregularity (Kleinman et al. 1991). All of these variants may be unilateral or bilateral. It is important to be familiar with their appearances in order that they are not mistaken for signs of abuse, with often devastating consequences. A metaphyseal step off is an acute, near 90 degree angulation in the extreme portion of the metaphysis adjacent to the physis (Fig. 7.68). The adjacent corti-... 

Fig. 11.2. Metaphyseal fractures. AP view of a knee shows the two typical appearances of corner fractures arrows) and a bucket handle fracture arrowhead)...

Fig. 11.3. A large bucket handle fracture. Note the thickness of the bone fragment at the periphery compared with the middle of the bone. When the thicker peripheral fragment is demonstrated without its central component, the appearances are those of a corner fracture...

Solder joints made with the SACX alloy demonstrated surface-solder fatigue, where the grains exhibited surface rippling or intrusion/extrusion behavior. Voids were found in both alloys. In this experiment, they appeared more prominent in the SACX alloy. It is important to note that no fractures originated at these voids in any of the cross-sections examined with either alloy. The release of surface energy manifests itself by surface distortion in the SACX alloy solder joints, and as corner fractures on solder joints made using an Sn/Cu/Ni alloy. 

It is 2 30 on Tuesday, August 22. You are driving Vehicle 25, heading west on NW 91st Street. Your coworker Alex Thorp is riding on the platform at the back of the truck. Just as you round the corner to head north on Park Place, he loses his grip and falls from the truck. You stop immediately to see if he is hurt. He says he s fine, but about an hour later his wrist hurts badly enough that he asks you to take him to the hospital. You go to the Mercy Medical Center. The doctor who examines him says the wrist is mildly fractured. 

Around 2 30 on Tuesday, August 22, Alex Thorp fell from the back platform of 25 while I was turning the corner from the west lane of NW 91st to go north on Park Place. About an hour later he asked to go to the hospital. The doctor said his wrist was fractured. 

On or about 2 30 on Tuesday, August 22, my coworker Alex Thorp and I were headed westbound on NW 91 St Street. As I proceeded around the corner to head northbound on Park Place, he lost his grip and suffered an unknown injury. Later we went to Mercy Medical Center to seek a doctor s attention, who said it was fractured wrist, only mildly. 

Around 2 30 on Tuesday, August 22, Alex Thorp lost his grip while riding on the back platform of Vehicle 25 as I was driving around the corner from NW 91 st west onto Park Place north. He didn t realize he was hurt until about an hour later. I took him to Mercy Medical Center where a doctor examined him and said he had a mildly fractured wrist. 

There are two main techniques used to measure the fracture toughness of ceramics fracture stress and hardness indentation. The former measures the load to fracture of a pre-cracked specimen using a single edge notched beam (SENB) or a chevron notched beam (CNB) sample. The main drawback of this technique is ensuring that the crack tip is atomically sharp. The second method uses the crack formed at the corners of the indentation produced during a Vickers indentation hardness test. This technique is rapid and relatively inexpensive. However, the toughness values measured are those of the surface, unlike the values obtained by fracture of the pre-cracked beams which are a measure of the bulk material properties. 

The Framework Minerals. A crystal of quartz may be desciibed as a single giant molecule, in trhich every atom is linked to the rest of the structure by silicon oxygen bonds. This crystal is hard and strong because any fracture requires that many of these chemical bonds be broken. The entire crystal may be described as made up of SiO tetra-hedra which are condensed together by sharing corners, that is, oxygen atoms, with one another the crystal has a tetrahedral frametvork structure. 

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