Developing Fused Deposition Modeling Additive Manufacturing Processing Strategies for Aluminum Alloy 7075: Sample Preparation and Metallographic Characterization

Currently, no commercial aluminum 7000 series filaments are available for making aluminum parts using fused deposition modeling (FDM)-based additive manufacturing (AM). The key technical challenge associated with the FDM of aluminum alloy parts is consolidating the loosely packed alloy powders in the brown-body, separated by thin layers of surface oxides and polymer binders, into a dense structure. Classical pressing and sintering-based powder metallurgy (P/M) technologies are employed in this study to assist the development of FDM processing strategies for making strong Al7075 AM parts. Relevant FDM processing strategies, including green-body/brown-body formation and the sintering processes, are examined. The microstructures of the P/M-prepared, FDM-like Al7075 specimens are analyzed and compared with commercially available FDM 17-4 steel specimens. We explored the polymer removal and sintering strategies to minimize the pores of FDM-Al7075-sintered parts. Furthermore, the mechanisms that govern the sintering process are discussed.     

Magnetic fluid hyperthermia (MFH)reduces prostate cancer growth in the orthotopic Dunning R3327 rat model

BACKGROUND: Magnetic fluid hyperthermia (MFH) is a new technique for interstitial hyperthermia or thermoablation based on AC magnetic field-induced excitation of biocompatible superparamagnetic nanoparticles. Preliminary studies in the Dunning tumor model of prostate cancer have demonstrated the feasibility of MFH in vivo. To confirm these results and evaluate the potential of MFH as a minimally invasive treatment of prostate cancer we carried out a systematic analysis of the effects of MFH in the orthotopic Dunning R3327 tumor model of the rat. METHODS: Orthotopic tumors were induced by implantation of MatLyLu-cells into the prostates of 48 male Copenhagen rats. Animals were randomly allocated to 4 groups of 12 rats each, including controls. Treatment animals received two MFH treatments following a single intratumoral injection of a magnetic fluid. Treatments were carried out on days 10 and 12 after tumor induction using an AC magnetic field applicator system operating at a frequency of 100 kHz and a variable field strength (0--18 kA/m). On day 20, animals were sacrificed and tumor weights in the treatment and control groups were compared. In addition, tumor growth curves were generated and histological examinations and iron measurements in selected organs were carried out. RESULTS: Maximum intratumoral temperatures of over 70 degrees C could be obtained with MFH at an AC magnetic field strength of 18 kA/m. At a constant field strength of 12.6 kA/m, mean maximal and minimal intratumoral temperatures recorded were 54.8 degrees C (centrally) and 41.2 degrees C (peripherally). MFH led to an inhibition of tumor growth of 44%-51% over controls. Mean iron content in the prostates of treated and untreated (injection of magnetic fluids but no AC magnetic field exposure) animals was 82.5%, whereas only 5.3% of the injected dose was found in the liver, 1.0% in the lung, and 0.5% in the spleen. CONCLUSIONS: MFH led to a significant growth inhibition in this orthotopic model of the aggressive MatLyLu tumor variant. Intratumoral deposition of magnetic fluids was found to be stable, allowing for serial MFH treatments without repeated injection. The optimal treatment schedules and temperatures for MFH need to be defined in further studies.     

Intensive care unit outcomes in elderly cancer patients

As the number of elderly patients receiving oncologic therapies increases, the need for better outcome predictors for the critically ill elderly with cancer increases. Physicians should not view age as an indicator of poor ICU outcome, as many elderly patients with cancer will derive the same benefit from intensive care as their younger counterparts. Such a gain can be accomplished without overuse of valuable resources. Similar prognostic factors that are applied to the younger cancer patients should also be applied to the elderly. These parameters, in addition to clinical judgment, can be helpful in deciding who will benefit from ICU care regardless of age. Oncologists and critical care physicians will need to collaborate and change the paradigm of ICU care for the elderly.     

Sinonasal facial pain

Evaluation of the paranasal sinuses and nasal cavity in patients with headache and or facial pain must include a thorough medical and social history, with close attention to the pattern and character of the pain, a thorough physical examination that includes a palpation and nasal endoscopy, and imaging studies such as CT scans and Magnetic Resonance Imaging. The physician must remember that every pain in the face is not caused by sinusitis.     

Fluoroscopic analysis of lumbar epidural contrast spread after lumbar interlaminar injection

Weil L, Frauwirth NH, Amirdelfan K, Grant D, Rosenberg JA. Fluoroscopic analysis of lumbar epidural contrast spread after lumbar interlaminar injection.

Objective

To describe and answer questions concerning the spread of contrast in patients receiving correctly placed lumbar epidural steroid injections (ESIs) under fluoroscopy.

Design

Prospective observational study.

Setting

An outpatient surgery center.

Participants

Consecutive patients (N=114) receiving ESIs under fluoroscopy who met inclusion criteria.

Interventions

Not applicable.

Main Outcome Measures

Spread of contrast in relation to variables, including unilateral versus bilateral, anterior versus posterior, and spread more than 1 level caudally versus less than 1 level. Variables were examined in relation to needle tip placement, level of injection, and male versus female patients. All data were collected with fluoroscopy images in lateral and anteroposterior views after injection of 5mL of fluid.

Results

Spread was greater than 1 segment caudally more than 75% of the time under all variables. Anterior versus posterior epidural spread on the lateral view was approximately even over all cases and anterior spread was found more often when the needle was within the width of the distal spinous process tip. Needle placement medial or lateral to the spinous process width also significantly affected whether the spread was unilateral versus bilateral. If the needle tip was lateral to the width of the spinous process, spread was unilateral 75% of the time, versus 45% of the time if the needle tip was medial.

Conclusions

Contrast spread is affected by needle placement, with other variables kept equal, in the performance of an interlaminar lumbar ESI. These data support the performance of interlaminar lumbar ESIs with fluoroscopic guidance and provide some parameters with which to guide the injectionist.     

Etiology, pathogenesis, and management of acute intraocular lens opacification: a systematic review

Millions of cataract surgeries with intraocular lens (IOL) implantation are performed worldwide. Although cataract surgery brings many benefits to the patients, the risk of various complications is still a concern. One of the infrequent adverse events but potentially affecting on patients’ visual acuity and contrast sensitivity is losing the transparency of IOL. IOL opacification may lead to IOL removal or exchange, which is unpleasant to both the patient and the surgeon. Several reports of acute IOL clouding are available in the literature describing various etiologies of this phenomenon, however, the exact mechanism remained unclear in some cases. Herein, we aimed to review the causes and outcomes of intraoperative and early postoperative IOL opacification.     

Phosphorylation and cleavage of the family of collapsin response mediator proteins may play a central role in neurodegeneration after CNS trauma

The family of the collapsin response mediator proteins (CRMPs) plays a significant physiological role in neuronal cell bodies and axons within the integrated mammalian central nervous system (CNS). Trauma-induced damage to the CNS results in variable degrees of axonal degeneration, and this may lead to neuronal cell death in key grey matter regions. Site-specific phosphorylation of certain CRMPs has been associated with trauma-induced axonal degeneration. Moreover, recent data implicate the pro-apoptotic, calcium-dependent protease calpain as a key initiator of CRMP cleavage. The primary cleavage product of injury-induced neuronal calpain activation is a C-terminus truncated 55- to 58-kDa form of CRMP, which may exert its effects within the cytoplasm and axonal core, or alternatively through its translocation into the nucleus, initiating neuronal cell death. The precise structure of cleaved CRMP has yet to be elucidated, as is the reason for nuclear translocation. Once the crystal structure of the cytoplasmic and nuclear-translocated forms of CRMPs is determined, a greater molecular understanding of why these forms can initiate neurodegeneration following CNS injury will be established. Such information will be particularly informative in the design of inhibitors of specific protein-protein interaction sites between cleaved CRMP and vital cytosolic or nuclear molecules.     

Clinical patterns of endothelial damage and thrombotic events in two patients with COVID‐19: A case report

Endotheliopathy causes COVID‐19 conflicting complications.