Emission measurement and safety assessment for the production process of silicon nanoparticles in a pilot-scale facility

Emission into the workplace was measured for the production process of silicon nanoparticles in a pilot-scale facility at the Institute of Energy and Environmental Technology e.V. (IUTA). The silicon nanoparticles were produced in a hot-wall reactor and consisted of primary particles around 60nm in diameter. We employed real-time aerosol instruments to measure particle number and lung-deposited surface area concentrations and size distribution; airborne particles were also collected for off-line electron microscopic analysis. Emission of silicon nanoparticles was not detected during the processes of synthesis, collection, and bagging. This was attributed to the completely closed production system and other safety measures against particle release which will be discussed briefly. Emission of silicon nanoparticles significantly above the detection limit was only observed during the cleaning process when the production system was open and manually cleaned. The majority of the detected particles was in the size range of 100-400nm and were silicon nanoparticle agglomerates first deposited in the tubing then re-suspended during the cleaning process. Appropriate personal protection equipment is recommended for safety protection of the workers during cleanin

Striatal dopamine and reward prediction error signaling in unmedicated schizophrenia patients

Increased striatal dopamine synthesis capacity has consistently been reported in patients with schizophrenia. However, the mechanism translating this into behavior and symptoms remains unclear. It has been proposed that heightened striatal dopamine may blunt dopaminergic reward prediction error signaling during reinforcement learning. In this study, we investigated striatal dopamine synthesis capacity, reward prediction errors, and their association in unmedicated schizophrenia patients (n = 19) and healthy controls (n = 23). They took part in FDOPA-PET and underwent functional magnetic resonance imaging (fMRI) scanning, where they performed a reversal-learning paradigm. The groups were compared regarding dopamine synthesis capacity (Kicer), fMRI neural prediction error signals, and the correlation of both. Patients did not differ from controls with respect to striatal Kicer. Taking into account, comorbid alcohol abuse revealed that patients without such abuse showed elevated Kicer in the associative striatum, while those with abuse did not differ from controls. Comparing all patients to controls, patients performed worse during reversal learning and displayed reduced prediction error signaling in the ventral striatum. In controls, Kicer in the limbic striatum correlated with higher reward prediction error signaling, while there was no significant association in patients. Kicer in the associative striatum correlated with higher positive symptoms and blunted reward prediction error signaling was associated with negative symptoms. Our results suggest a dissociation between striatal subregions and symptom domains, with elevated dopamine synthesis capacity in the associative striatum contributing to positive symptoms while blunted prediction error signaling in the ventral striatum related to negative symptoms

Traumatic Events, Social Adversity and Discrimination as Risk Factors for Psychosis - An Umbrella Review

Exposure to childhood trauma is a well-known risk factor for severe mental disorders including schizophrenia and other non-affective psychoses. Beyond childhood trauma, there is increasing evidence that bullying, social exclusion, and discrimination during adolescence and adulthood may increase the risk of developing a psychotic disorder, and that such forms of traumatization may also underlie the elevated psychosis risk among migrants or persons with a visible minority status. In this umbrella review, we systematically assess meta-analyses regarding trauma and social adversity. A systematic literature review yielded 11 meta-analyses that met inclusion criteria and could be summarized quantitatively with a random effect model. Furthermore, six meta-analyses were evaluated qualitatively. Heterogeneity and publication bias were apparent in several meta-analyses. We observed that most significant social risk factors for psychosis were vulnerability for racist discrimination [OR = 3.90 (3.25-4.70)], migration [OR = 2.22 (1.75-2.80)], and childhood adversities [OR = 2.81 (2.03-3.83)]. Furthermore, social factors increasing the risk for psychosis were variation/impairment of parental communication, aversive adult life events, bullying, and factors associated with social isolation and discrimination. In spite of these environmental risk factors, there is a lack of evidence regarding treatment of trauma and psychosis, although some psychotherapeutic and art therapy approaches appear to be promising. Beyond individual interventions, stigmatization, racism, and other forms of discrimination need to be targeted to increase solidarity and communal support

Deagglomeration testing of airborne nanoparticle agglomerates: stability analysis under varied aerodynamic shear and relative humidity conditions

Occupational exposure to nanomaterial aerosols poses potential health risks to workers at nanotechnology workplaces. Understanding the mechanical stability of airborne nanoparticle agglomerates under varied mechanical forces and environmental conditions is important for estimating their emission potential and the released particle size distributions which in consequence alters their transport and human uptake probability. In this study, two aerosolization and deagglomeration systems were used to investigate the potential for deagglomeration of nanopowder aerosols with different surface hydrophilicity under a range of shear forces and relative humidity conditions. Critical orifices were employed to subject airborne agglomerates to the shear forces induced by a pressure drop. Increasing applied pressure drop were found to be associated with decreased mean particle size and increased particle number concentrations. Rising humidity decreased the deagglomeration tendency as expressed by larger modal particle sizes and lower number concentrations compared to dry conditions. Hydrophilic aerosols exhibited higher sensitivities to changes in humidity than hydrophobic particles. However, the test systems themselves also differed in generated particle number concentrations and size distributions, which in turn altered the responses of created aerosols to humidity changes. The results of the present study clearly demonstrate that a) humidity control is essential for dustiness and deagglomeration testing, b) that (industrial) deagglomeration, e.g. for preparation of aerosol suspensions, can be manipulated by subjecting airborne particles to external energies, and c) that the humidity of workplace air may be relevant when assessing occupational exposure to nanomaterial aerosols

Australian guideline on prevention of foot ulceration: part of the 2021 Australian evidence-based guidelines for diabetes-related foot disease

Background: There are no current Australian guidelines on the prevention of diabetes-related foot ulceration (DFU). A national expert panel aimed to systematically identify and adapt suitable international guidelines to the Australian context to create new Australian evidence-based guidelines on prevention of first-ever and/or recurrent DFU. These guidelines will include for the first-time considerations for rural and remote, and Aboriginal and Torres Strait Islander peoples. Methods: The National Health and Medical Research Council procedures were followed to adapt suitable international guidelines on DFU prevention to the Australian health context. This included a search of public databases after which the International Working Group on the Diabetic Foot (IWGDF) prevention guideline was deemed the most appropriate for adaptation. The 16 IWGDF prevention recommendations were assessed using the ADAPTE and GRADE systems to decide if they should be adopted, adapted or excluded for the new Australian guideline. The quality of evidence and strength of recommendation ratings were re-evaluated with reference to the Australian context. This guideline underwent public consultation, further revision, and approval by national peak bodies. Results: Of the 16 original IWGDF prevention recommendations, nine were adopted, six were adapted and one was excluded. It is recommended that all people at increased risk of DFU are assessed at intervals corresponding to the IWGDF risk ratings. For those at increased risk, structured education about appropriate foot protection, inspection, footwear, weight-bearing activities, and foot self-care is recommended. Prescription of orthotic interventions and/or medical grade footwear, providing integrated foot care, and self-monitoring of foot skin temperatures (contingent on validated, user-friendly and affordable systems becoming available in Australia) may also assist in preventing DFU. If the above recommended non-surgical treatment fails, the use of various surgical interventions for the prevention of DFU can be considered. Conclusions: This new Australian evidence-based guideline on prevention of DFU, endorsed by 10 national peak bodies, provides specific recommendations for relevant health professionals and consumers in the Australian context to prevent DFU. Following these recommendations should achieve better DFU prevention outcomes in Australia

System Identification Method for Brake Particle Emission Measurements of Passenger Car Disc Brakes on a Dynamometer

Besides particulate emissions from engine exhausts, which are already regulated by emission standards, passenger car disc brakes are a source of particulate matter. With the current car fleet it is estimated that up to 21% of the total traffic related PM10 emissions in urban environments originate from brake wear and reduction of brake dust emissions is subject of current research. For the purpose of reducing brake dust emissions by choosing low-emission operating points of the disc brake, the knowledge of the emission behavior depending on brake pressure, wheel speed, temperature and friction history is of interest. According to the current state of research, theoretical white box modeling of the emission behavior is complicated due to the complexity of tribological contact between pad and disc. Thus experimental black box modeling is supposed to describe emission behavior. In order to minimize the influence of disturbances and therefore to improve prediction accuracy of such empirical models, system identification methods based on periodical test signals, such as brake pressure sine, are used for this application. To adopt these test signals, which are established in transfer function measurements, to the application of brake particle measurements and to develop an experimental design, system theoretical quantities, such as cutoff frequency, signal to noise ratio and hysteresis, are determined in dynamometer tests. Therefore measurements of the system’s response to step and sine test signals are analyzed. System identification is executed and the applicability of periodical test signals to brake particle measurements is proven

Fine and ultrafine particles from indoor sources – Effects on healthy humans in a controlled exposure study and on lung epithelial cells in vitro

In recent years increasing concern has been expressed about the potential adverse health effects of particles from indoor sources. The aims of the EPIA project were: (1) to characterize potentially relevant indoor sources of (ultra)fine particles with respect to their emission levels and composition and (2) to investigate their adverse health effects. We investigated the effects of emissions from candle burning (CB), toasting of bread (TB) and sausage frying (FS) in a randomized, cross-over sham-controlled exposure study in healthy adults as well as in vitro in A549 human lung epithelial cells. Participants were exposed for 2 h to each of these sources at two different exposure levels, and examined before, during and after the exposures at defined time-intervals. We found transient associations between exposures and several respiratory and cardiovascular effects as well as inflammatory changes (e.g. lung function, blood pressure, arterial stiffness, interleukin-8 in nasal lavage/blood). Specific effects were found to depend strongly on the emission source and the selected exposure metric (e.g. size-specific particle mass concentration, size-specific particle number concentration, lung deposited surface area concentration). Evaluation of PM2.5 samples in the A549 cells, revealed an increased interleukin-8 release and DNA strand breakage induction for toasting, whereas candle burning only resulted in DNA damage. The results from our project demonstrate that elevated concentrations from certain indoor emission sources may lead to changes in the lung and cardiovascular systems as well as possibly induce inflammation

Dustiness and deagglomeration testing: interlaboratory comparison of systems for nanoparticle powders

Different types of aerosolization and deagglomeration testing systems exist for studying the properties of nanomaterial powders and their aerosols. However, results are dependent on the specific methods used. In order to have well-characterized aerosols, we require a better understanding of how system parameters and testing conditions influence the properties of the aerosols generated. In the present study, four experimental setups delivering different aerosolization energies were used to test the resultant aerosols of two distinct nanomaterials (hydrophobic and hydrophilic TiO2). The reproducibility of results within each system was good. However, the number concentrations and size distributions of the aerosols created varied across the four systems; for number concentrations, e.g., from 10(3) to 10(6) #/cm(3). Moreover, distinct differences were also observed between the two materials with different surface coatings. The article discusses how system characteristics and other pertinent conditions modify the test results. We propose using air velocity as a suitable proxy for estimating energy input levels in aerosolization systems. The information derived from this work will be especially useful for establishing standard operating procedures for testing nanopowders, as well as for estimating their release rates under different energy input conditions, which is relevant for occupational exposure

Dilatons in Hidden Local Symmetry for Hadrons in Dense Matter

With the explicit breaking of scale invariance by the trace anomaly of QCD rephrased in terms of spontaneous breaking, low-energy strong interaction dynamics of dense (and also hot) matter can be effectively captured by -- in addition to the Nambu-Goldstone bosons and the vector mesons -- two dilaton fields, the "soft" ($\chi_s$) field that is locked to chiral symmetry and the "hard" ($\chi_h$) field which remains unaffected by chiral symmetry. The interplay of the soft and hard dilatons plays a subtle role in how chiral symmetry is manifested in hot and/or dense matter. The scale anomaly in which the soft component intervenes vanishes at the chiral transition in a way analogous to the restoration of scale symmetry in the Freund-Nambu model, while that of the hard component remains broken throughout the QCD sector. Most remarkable of all is its role in the chiral anomaly sector through a "homogeneous Wess-Zumino (hWZ) term" of the form $\omega_\mu B^\mu$ on the structure of a single baryon as well as dense baryonic matter. It figures crucially in predicting a "Little Bag" for the nucleon and a "quarkyonic phase" in the form of a half-skyrmion matter at high density. We show how the vanishing of the vector-meson mass at the vector manifestation fixed point in hidden local symmetry theory can be related to the property of the "matter field" in the Freund-Nambu model that leaves scale symmetry invariant. The emerging structure of dense hadronic matter in the model so constructed suggests what could be amiss in describing dense matter in holographic dual QCD at its large $N_c$ and 't Hooft limit.Comment: 28 pages, 2 figures; additional reference