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The fumes created from welding activities present a unique occupational hazard. Due to the complex processes which govern fume formation, the characterization of welding fumes is difficult. Emission factors (EFs) are one method to characterize fume formation from different processes and scenarios. This paper reviews the development of EFs and similar metrics both historic research which contributed to the US EPAs AP-42 summary of welding emission factors released in 1995, and more recent research initiatives. Through a critical analysis of what research has been done in this area and the strength of the emission factors developed, this paper proposes a set of recommendations for future research. Research on emission factors for gas metal arc welding (GMAW) is the most complete amongst the different types of electric arc welding. Despite it being generally known that flux core arc welding (FCAW) creates significant fume emissions compared to some of the other processes few studies have looked at FCAW since the AP-42. Shielded metal arc welding is also under-researched particularly in terms of metal-specific emission factors. The influence of different welding activity parameters such as welding location, speed or current is well defined for GMAW but requires more attention for other welding processes. Further effort towards compiling and comparing available emission factor data of quality, evaluating the available data statistically and organizing this data in a practically useful way is required. The availability of reliable emission factors will allow the development or improvement of exposure modelling tools that would be very useful for exposure assessment when monitoring is not practical.s

A conical test chamber was built to quantify emission factors for various types of welding processes. The chamber was built according to American Welding Society (AWS) standard F1.2:2013. Fumes were collected on pre-dried and pre-weighted 293 mm glass fiber filters using a high-volume sampling pump running at approximately 30 cfm. Consumables were weighted before and after welding to calculate the amount of fume emitted per weight of consumable. All the welding was performed by a professional welder. The chamber was calibrated prior to any use to adjust the flowrate inside the chamber. The test chamber was used to calculate emission factors for Shielded Metal Arc Welding process using four different electrodes (E6013, E6011, E7018, E7014) and three different currents for each electrode as fume emission increases with current. Each test was done in triplicates to investigate for variation. Emission factors were calculated by diving the amount of fume on the filters by the weight of consumables used (g/kg). In general test were reproducible with coefficient of variations varying from 0.2 to 18.1% with most variation below 15%. Emission factors were highly dependent on the type of electrode with the lowest values found for E6013 and the highest for E6011. Emission factors increased significantly with increasing current. The chamber works properly and can be used to test other processes such as Gas Metal Arc Welding, Metal Core Arc Welding, Flux Core Arc Welding, as well as Gas Tungsten Arc Welding. Emission factors will also be calculated for metals.

Purpose Pancreatic cancer is typically diagnosed in a late stage with limited therapeutic options. For those patients, ultrasound-guided high-intensity focused ultrasound (US-HIFU) can improve local control and alleviate pain. However, MRI-guided HIFU (MR-HIFU) has not yet been studied extensively in this context. To facilitate related research and accelerate clinical translation, we report a workflow for the in vivo HIFU ablation of the porcine pancreas under MRI guidance. Materials and methods The pancreases of five healthy German landrace pigs (35–58 kg) were sonicated using a clinical MR-HIFU system. Acoustic access to the pancreas was supported by a specialized diet and a hydrogel compression device for bowel displacement. Organ motion was suspended using periods of apnea. The size of the resulting thermal lesions was assessed using the thermal threshold- and dose profiles, non-perfused volume, and gross examination. The effect of the compression device on beam path length was assessed using MRI imaging. Results Eight of ten treatments resulted in clearly visible damage in the target tissue upon gross examination. Five treatments resulted in coagulative necrosis. Good agreement between the four metrics for lesion size and a clear correlation between the delivered energy dose and the resulting lesion size were found. The compression device notably shortened the intra-abdominal beam path. Conclusions We demonstrated a workflow for HIFU treatment of the porcine pancreas in-vivo under MRI-guidance. This development bears significance for the development of MR-guided HIFU interventions on the pancreas as the pig is the preferred animal model for the translation of pre-clinical research into clinical application.

Facemask use has been a key public health measure in response to the SARS CoV-2 pandemic; they are used to reduce airborne transmission of the disease amongst the public. The facemasks used by the public are non-medical in nature and therefore are not regulated like medical masks. Cloth masks, both commercially sourced and homemade have been used throughout the pandemic. Cloth mask suitability for protection from transmission of SARS-CoV-2 is still being determined, while new research is emerging, knowledge is limited on this topic, especially due to the variety in materials and use scenarios. Understanding filtration efficiencies of different materials in different use scenarios is key for public health during this and potentially future respiratory infectious disease outbreaks. A testing line using NaCl challenge aerosol is used to evaluate the filtration efficiency and pressure drop for a variety of materials, commercially sourced non-medical masks, and medical masks. The testing line and procedure is closely adapted from the ASTM F2299 testing method used for testing medical masks. Materials and masks were tested individually as well as in various combinations. Four mask types were also tested at four different face velocities, three within the acceptable face velocity range allowed for ASTM F2299 certification and the other masks and materials were tested at two face velocities. Masks were also exposed to aerated simulated exhaled breath condensate (EBC) for 1 to 24 hours and their filtration efficiency was tested immediately following exposure. Both hygroscopic and hydrophobic masks were tested after exhaled breath condensate exposure. Statistical analysis was used to identify correlation between breath condensate exposure duration and filtration efficiency and pressure drop. Filtration efficiencies at 0.15 µm at a face velocity of 25 cm/s for commercial cloth masks, disposable non-medical masks, medical masks, commercial mask combinations and homemade combinations were, 16-29%, 39-76%, 91-97%, 51-95%, 45-94% respectively. The quality factors (QF) for this data ranged from 2.3 to 36 kpa-1. On average, the filtration efficiency decreased as face velocity of the challenge aerosol stream increased. The only masks that did not follow this trend were the woven and knitted materials and two of the commercial masks made with cotton. Filtration efficiency decreased by up to 20% after EBC exposure. Two masks had statistically significant correlations between filtration and EBC exposure time at 1.0 µm; other masks showed similar trends but were not statistically significant. There was no strong correlation between EBC exposure and pressure drop. With proper layering, household materials can achieve high filtration efficiency and breathability requirements similar to medical masks. More regulation of disposable and cloth masks are needed considering the large variety in masks quality. The velocity range allowed for medical mask testing as per ASTM F2299 is too large and should be revised. Filtration efficiency varies within this range which means masks that are all certified under this standard can be inconsistent. Cloth masks should be removed and cleaned after an 8-hour workday. If possible, removal after 4-hours would be preferred. Medical and non-medical disposable masks are not largely impacted by breath condensate and therefore should be worn according to manufacturer's specifications. Further research should be conducted on the subject of how filtration mechanisms are impacted by breath condensate and on the subject of mask maintenance and lifespan which was not included in this scope.

Encapsulation of cytotoxic drugs for a localized release is an effective way to increase the therapeutic window of such agents. In this article we present the localized release of doxorubicin (DOX) from phosphatidyldiglycerol (DPPGGerman landrace pigs of weights between 37.5 and 53.5 kg received a 30-min infusion of DOX containing thermosensitive liposomes (50 mg DOX/mCompared to untreated tissue, we found a 15-fold and a 7-fold increase in DOX concentration in the muscle volumes that had undergone hyperthermia starting 10 min and 60 min after the beginning of the infusion, respectively. The pharmacokinetic analysis showed a prolonged circulation time of DOX and a correlation between the AUC of extra-liposomal DOX in the bloodstream and the amount of DOX accumulated in the target tissue.We have demonstrated a workflow for MR-HIFU hyperthermia drug delivery that can be adapted to a clinical setting, showing that HIFU-hyperthermia is a suitable method for local drug release of DOX using DPPG

Purpose The expression of active tissue factor (TF) on the surface of microvesicles (MVs) is essential for the activation of the coagulation system and transduction of the signaling pathways in cancer cells. In its use as a biomarker for cancer-associated venous thromboembolism (VTE), TF has shown high expression variability. As a contribution to this discussion, we present a study investigating plasma samples from patients with various progressive tumors at high risk for VTE. Methods Based on our previous study uncovering microvesicles (MVs), the larger ectosome-like extracellular vesicles (EV), as the major source of TF activity in EV preparations, we now determined TF activity on enriched MVs isolated from plasma of cancer patients and compared it with that on MVs from healthy individuals. Results We found considerably higher amounts of MVs as well as higher levels of MV-bound TF activities in the plasma of cancer patients. We also show that preparations from plasma of cancer patients have the potency to induce ERK phosphorylation in a human tumor cell line through proteinase-activated receptor two (PAR2) activation. Conclusion We suggest that MVs instead of whole EV preparations, and TF activity rather than its antigenic quantification should be used in clinical studies for identifying patients with progressive tumors at high risk for VTE. Graphic abstract