Frequency domain measurements of melt pool recoil force using modal analysis.

Recoil pressure is a critical factor affecting the melt pool dynamics during Laser Powder Bed Fusion (LPBF) processes. Recoil pressure depresses the melt pool. When the recoil pressure is low, thermal conduction and capillary forces may be inadequate to provide proper fusion between layers. However, excessive recoil pressure can produce a keyhole inside the melt pool, which is associated with gas porosity. Direct recoil pressure measurements are challenging because it is localized over an area proportionate to the laser spot size producing a force in the mN range. This paper reports a vibration-based approach to quantify the recoil force exerted on a part in a commercial LPBF machine. The measured recoil force is consistent with estimates from high speed synchrotron imaging of entrained particles, and the results show that the recoil force scales with applied laser power and is inversely related to the laser scan speed. These results facilitate further studies of melt pool dynamics and have the potential to aid process development for new materials.

A pathologist's survey on the reporting of sessile serrated adenomas/polyps.

AIM: The purpose of this survey was to ascertain reporting habits of pathologists towards sessile serrated adenomas/polyps (SSA/P). METHODS: A questionnaire designed to highlight diagnostic criteria, approach and clinical implications of SSA/P was circulated electronically to 45 pathologists in the UK and North America. RESULTS: Forty-three of 45 pathologists agreed to participate. The vast majority (88%) had a special interest in gastrointestinal (GI) pathology, had great exposure to GI polyps in general with 40% diagnosing SSA/P at least once a week if not more, abnormal architecture was thought by all participants to be histologically diagnostic, and 11% would make the diagnosis if a single diagnostic histological feature was present in one crypt only, while a further 19% would diagnose SSA/P in one crypt if more than one diagnostic feature was present. The vast majority agreed that deeper sections were useful and 88% did not feel proliferation markers were useful. More than one-third did not know whether, or did not feel that, their clinicians were aware of the implications of SSA/P. CONCLUSIONS: 98% of pathologists surveyed are aware that SSA/P is a precursor lesion to colorectal cancer, the majority agree on diagnostic criteria, and a significant number feel that there needs to be greater communication and awareness among pathologists and gastroenterologists about SSA/P.

The role of fungi in the etiology of chronic rhinosinusitis: a prospective study.

OBJECTIVES: Allergic fungal sinusitis (AFS) may represent an endpoint in a spectrum of sinonasal disease. Patients fulfilling criteria for a diagnosis of AFS have a poor prognosis often requiring multiple surgeries. The detection of 'allergic mucin' with mucus containing clusters of eosinophils and the detection of fungi by histological examination or culture is key criteria necessary for diagnosis. This study was performed to assess the strength of the association of the presence of fungi with the presence of eosinophils in a group of patients with chronic rhinosinusitis and controls. METHODS: Thirty patients with a clinical diagnosis of chronic rhinosinusitis and 10 individuals as control group were selected for the study. Total serum IgE level testing, nasal mucus cytology and fungal culture were performed in all subjects. RESULTS: Fungal spores were present in the nasal mucus in 14 patients with rhinosinusitis, and in 7 controls. The detection of eosinophils on cytology correlated significantly both with a clinical diagnosis of chronic rhinosinusitis (95% confidence intervals (CI) 0.34-0.81) and with the presence of fungal elements on cytology (p=0.02). The average serum IgE level was higher in patients with fungal spores (p=0.039). CONCLUSION: In certain susceptible individuals inhaled fungi may provoke an eosinophilic response. This response varies from simple eosinophilic inflammation to classic allergic fungal sinusitis.

Levobetaxolol-induced Up-regulation of retinal bFGF and CNTF mRNAs and preservation of retinal function against a photic-induced retinopathy.

Betaxolol (racemic), a beta-adrenoceptor antagonist that is used to lower intraocular pressure in the treatment of glaucoma, has been shown to protect inner retina cells from various insults. To determine if such protection could be afforded to retinal photoreceptors and retinal pigment epithelial cells (RPE), levobetaxolol (S-betaxolol) was evaluated in a photic-induced retinopathy model. Rats were dosed (IP) with vehicle or levobetaxolol (10 and 20 mg kg(-1)) 48, 24 and 0 hr prior to exposure for 6 hr to fluorescent blue light. The electroretinogram (ERG) and retinal morphology were assessed after a 3 week recovery period. Evaluation of the ERG demonstrated significant protection of retinal function in levobetaxolol (20 mg kg(-1))-dosed rats compared to vehicle-dosed rats. Similarly, the RPE and outer nuclear layer were significantly thicker in levobetaxolol (20 mg kg(-1))-dosed rats compared to vehicle-dosed rats. To elucidate potential mechanism(s) of the neuroprotective activity of levobetaxolol, bFGF and CNTF mRNA levels in normal rat retinas were evaluated 12 hr after a single i.p. injection. Northern blot analysis of levobetaxolol treated retinas demonstrated a 10-fold up-regulation of bFGF and a two-fold up-regulation of CNTF mRNA levels, trophic factors that have been shown to inhibit retinal degeneration in a number of species. These studies suggest that levobetaxolol can be used as a novel neuroprotective agent to ameliorate retinopathy.