Digital and Analog Detection of SARS-CoV-2 Nucleocapsid Protein via an Upconversion-Linked Immunosorbent Assay.

The COVID-19 crisis requires fast and highly sensitive tests for the early stage detection of the SARS-CoV-2 virus. For detecting the nucleocapsid protein (N protein), the most abundant viral antigen, we have employed upconversion nanoparticles that emit short-wavelength light under near-infrared excitation (976 nm). The anti-Stokes emission avoids autofluorescence and light scattering and thus enables measurements without optical background interference. The sandwich upconversion-linked immunosorbent assay (ULISA) can be operated both in a conventional analog mode and in a digital mode based on counting individual immune complexes. We have investigated how different antibody combinations affect the detection of the wildtype N protein and the detection of SARS-CoV-2 (alpha variant) in lysed culture fluid via the N protein. The ULISA yielded a limit of detection (LOD) of 1.3 pg/mL (27 fM) for N protein detection independent of the analog or digital readout, which is approximately 3 orders of magnitude more sensitive than conventional enzyme-linked immunosorbent assays or commercial lateral flow assays for home testing. In the case of SARS-CoV-2, the digital ULISA additionally improved the LOD by a factor of 10 compared to the analog readout.

Assessment Team Recommendations on the Continuation of Involuntary Commitment in Poland.

This study explores explicit justifications for recommendations regarding patients' continuing detention in forensic psychiatric wards. We are interested in what arguments are used in recommendations for the continuing detention of involuntarily committed patients made by assessment teams for legal proceedings. Our frequency analysis shows that assessment teams refer predominantly to arguments related to the mental state of the detainee. When recommending a change of security level, the assessment teams frequently refer to behavioural factors. However, very rarely does such argumentation appear in recommendations for continuation of detention at the same security level. Additionally, our qualitative analysis shows a very high level of certainty with which pronouncements about patients' behaviour are made, typically in the absence of any social/institutional context. Our study shows that assessment teams tend to opt for safe decisions that are unlikely to be challenged by legal proceedings and that allow them full control over the patient.

The question-behaviour effect in intergroup attitudes research: When do attitudes towards a minority predict a relevant behaviour?

We hypothesised that the question-behaviour effect, referred to as the influence of questioning about a given behaviour on its subsequent performance, is a relevant issue when exploring the external validity of intergroup attitudes. In a pair of studies, we have corroborated that merely expressing attitudes towards the Jewish minority affects people's relevant behaviour towards this group. In an Internet study, participants who first completed verbal attitude measures were more likely to donate to a Jewish organisation compared to those who completed the measures after making the decision to donate. Moreover, responses to attitude measures of various types and donating to the Jewish organisation were correlated when attitudes had been expressed in the first step. When attitudes were measured after the decision to donate, only the responses to the traditional anti-Semitic scale were correlated with this behaviour. In the field study, in which the time interval between attitude and behaviour measures was introduced, no question-behaviour effect was observed. We explain the results with reference to cognitive dissonance and attitude accessibility mechanisms and discuss them in a broader context of attitude-behaviour research.

Formation Mechanism, Structural, and Upconversion Properties of Alkaline Rare-Earth Fluoride Nanocrystals Doped With Yb3+/Er3+ Ions.

Ultrasmall (9-30 nm) Yb3+/Er3+-doped, upconverting alkaline rare-earth fluorides that are promising for future applications were synthesized by the microwave-assisted hydrothermal method. The formation mechanism was proposed, indicating the influence of the stability of metal ions complexes with ethylenediaminetetraacetic acid on the composition of the product and tendency to form M2REF7 (M0.67RE0.33F2.33) cubic compounds in the M-RE-F systems. Their physicochemical properties (structure, morphology, and spectroscopic properties) are compared and discussed. The obtained nanoparticles exhibited emission of light in the visible spectra under excitation by 976 nm laser radiation. Excitation and emission spectra, luminescence decays, laser energy dependencies, and upconversion quantum yields were measured to determine the spectroscopic properties of prepared materials. The Yb3+/Er3+ pair of ions used as dopants was responsible for an intense yellowish-green emission. The upconversion quantum yields determined for the first time for M2REF7-based materials were 0.0192 ± 0.001% and 0.0176 ± 0.001% for Sr2LuF7:Yb3+,Er3+ and Ba2LuF7:Yb3+,Er3+ respectively, the two best emitting samples. These results indicated the prepared materials are good and promising alternatives for the most studied NaYF4:Yb3+,Er3+ nanoparticles.

Perpetrator as a Potential Victim. Does Threatened Retaliation from the Victim Reduce Obedience towards Authority?

In an experiment conducted within the Milgram paradigm, it was examined whether obedience towards an authority would be reduced in conditions in which the teacher had grounds to fear revenge from the learner. A comparison was made of the behaviour of participants in classic conditions and in conditions in which they were told that following the first part of the experiment, there would be an alteration of roles: the teacher would become the learner. It turned out that the level of compliance was the same in both groups. The dominant behaviour, regardless of whether the participant expects a change of roles or not, is total obedience.

Synthesis and organic surface modification of luminescent, lanthanide-doped core/shell nanomaterials (LnF3@SiO2@NH2@organic acid) for potential bioapplications: spectroscopic, structural, and in vitro cytotoxicity evaluation.

A facile coprecipitation reaction between Ce(3+), Gd(3+), Tb(3+), and F(-) ions, in the presence of glycerine as a capping agent, led to the formation of ultrafine, nanocrystalline CeF3:Tb(3+) 5%, Gd(3+) 5% (LnF3). The as-prepared fluoride nanoparticles were successfully coated with an amine modified silica shell. Subsequently, the obtained LnF3@SiO2@NH2 nanostructures were conjugated with 4-ethoxybenzoic acid in order to prove the possibility of organic modification and obtain a new functional nanomaterial. All of the nanophosphors synthesized exhibited intense green luminescence under UV light irradiation. Based on TEM (transmission electron microscopy) measurements, the diameters of the cores (≈12 nm) and core/shell particles (≈50 nm) were determined. To evaluate the cytotoxic activity of the nanomaterials obtained, their effect on human erythrocytes was investigated. LnF3 nanoparticles were bound to the erythrocyte membrane, without inducing any cytotoxic effects. After coating with silica, the nanoparticles revealed significant cytotoxicity. However, further functionalization of the nanomaterial with -NH2 groups as well as conjugation with 4-ethoxybenzoic acid entailed a decrease in cytotoxicity of the core/shell nanoparticles.

Structural, spectroscopic, and magnetic properties of Eu3+-doped GdVO4 nanocrystals synthesized by a hydrothermal method.

New interesting aspects of the spectroscopic properties, magnetism, and method of synthesis of gadolinium orthovanadates doped with Eu(3+) ions are discussed. Gd(1-x)Eu(x)VO4 (x = 0, 0.05, 0.2) bifunctional luminescent materials with complex magnetic properties were synthesized by a microwave-assisted hydrothermal method. Products were formed in situ without previous precipitation. The crystal structures and morphologies of the obtained nanomaterials were analyzed by X-ray diffraction and transmission and scanning electron microscopy. Crystallographic data were analyzed using Rietveld refinement. The products obtained were nanocrystalline with average grain sizes of 70-80 nm. The qualitative and quantitative elemental composition as well as mapping of the nanocrystals was proved using energy-dispersive X-ray spectroscopy. The spectroscopic properties of red-emitting nanophosphors were characterized by their excitation and emission spectra and luminescence decays. Magnetic measurements were performed by means of vibrating sample magnetometry. GdVO4 and Gd0.8Eu0.2VO4 exhibited paramagnetic behavior with a weak influence of antiferromagnetic couplings between rare-earth ions. In the substituted sample, an additional magnetic contribution connected with the population of low-lying excited states of europium was observed.

Obedience to authority as a function of the physical proximity of the student, teacher, and experimenter.

The authors are proposing a theoretical model explaining the behavior of individuals tested through experiments on obedience toward authority conducted according to Milgram's paradigm. Their assumption is that the participant faces typical avoidance-avoidance conflict conditions. Participant does not want to hurt the learner in the adjacent room but he or she also does not want to harm the experimenter. The solution to this conflict, entailing hurting on of the two, may be different depending on the spatial organization of the experiment. In the study, experimental conditions were modified, so that the participant was (vs. was not) in the same room as the experimenter and was (vs. was not) in the same room as the learner. Forty individuals (20 women and 20 men) were tested in each of the four experimental conditions. It turns out that the physical presence of the experimenter was conducive to obedience, while the physical presence of the learner reduced it.

The use of energy looping between Tm3+ and Er3+ ions to obtain an intense upconversion under the 1208 nm radiation and its use in temperature sensing.

The upconversion phenomenon allows for the emission of nanoparticles (NPs) under excitation with near-infrared (NIR) light. Such property is demanded in biology and medicine to detect or treat diseases such as tumours. The transparency of biological systems for NIR light is limited to three spectral ranges, called biological windows. However, the most frequently used excitation laser to obtain upconversion is out of these ranges, with a wavelength of around 975 nm. In this article, we show an alternative - Tm3+/Er3+-doped NPs that can convert 1208 nm excitation radiation, which is in the range of the 2nd biological window, to visible light within the 1st biological window. The spectroscopic properties of the core@shell NaYF4:Tm3+@NaYF4 and NaYF4:Er3+,Tm3+@NaYF4 NPs revealed a complex mechanism responsible for the observed upconversion. To explain emission in the studied NPs, we propose an energy looping mechanism: a sequence of ground state absorption, energy transfers and cross-relaxation (CR) processes between Tm3+ ions. Next, the excited Tm3+ ions transfer the absorbed energy to Er3+ ions, which results in green, red and NIR emission at 526, 546, 660, 698, 802 and 982 nm. The ratio between these bands is temperature-dependent and can be used in remote optical thermometers with high relative temperature sensitivity, up to 2.37%/°C at 57 °C. The excitation and emission properties of the studied NPs fall within 1st and 2nd biological windows, making them promising candidates for studies in biological systems.

Hydrothermal synthesis and structural and spectroscopic properties of the new triclinic form of GdBO3:Eu3+ nanocrystals.

Triclinic Gd1-xEuxBO3 nanophosphors have been prepared by a hydrothermal method without using additional coreagents and prior precipitation of precursor (in situ). The formation of the borate nanorods and their crystal structure was refined on the basis of X-ray diffraction patterns (XRD) and well confirmed using various techniques such as infrared spectroscopy (IR), Raman spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The new triclinic crystal structure (space group P1) for the GdBO3 nanocrystals and detailed structure parameters were determined with the help of the Rietveld analysis. The spectroscopic characteristics of the synthesized nanomaterials with different concentrations of Eu(3+) ions were defined with the use of luminescence excitation spectra as well as emission spectra and decay kinetics. The Judd-Ofelt parameters (Ω2, Ω4) and quantum efficiency, η, were also calculated for the more detailed analysis of Eu(3+) spectra in the GdBO3 host.

You and I are alike, so I will hold back - The effect of directed empathy on the behavior of participants of Stanley Milgram's obedience paradigm.

Experiments on obedience to authority conducted under the paradigm developed by Milgram have demonstrated that empathy plays either no or a very limited role in determining participants' behaviors. This study proposes that this occurs due to participants empathizing with both "learners" and experimenters. Empathy with learners makes participants withdraw from the experiment, while empathy with experimenters makes them continue. Therefore, the more that participants are characterized by dispositional empathy, the more they are reluctant to hurt learners but, at the same time, the more they try not to disappoint experimenters. This study investigates the effects of empathy being situationally directed toward learners. After manipulating the alleged similarities between "teachers" and "learners" in terms of crucial attitudes and values, the degree to which teachers obeyed experimenters and were willing to electrocute learners was measured. The results confirm that situationally directed empathy reduces participants' obedience to experimenters.

Designing photon upconversion nanoparticles capable of intense emission in whole human blood.

The properties of upconverting nanoparticles (UCNPs) are crucial for their applications in biomedicine. For studies of organisms and biological materials, the penetration depth of excitation light is also essential as the depth from which the luminescence can be detected. Currently, many researchers are trying to obtain UCNPs with intense emission under excitation wavelengths from the biological transparency windows to increase the penetration depth. However, studies comparing the properties of various types of UCNPs in real conditions are rare. This article shows how deep the 808, 975, 1208, and 1532 nm laser radiation penetrates human blood. Moreover, we determined how thick a layer of blood still permits for observation of the luminescence signal. The measured luminescence properties indicated that the near-infrared light could pass through the blood even to a depth of 7.5 mm. The determined properties of core/shell NaErF4/NaYF4 materials are the most advantageous, and their emission is detectable through 3.0 mm of blood layer using a 1532 nm laser. We prove that the NaErF4/NaYF4 UCNPs can be perfect alternatives for the most studied NaYF4:Yb3+,Er3+/NaYF4. Additionally, the setup proposed in this article can potentially decrease reliance on animal testing in initial biomedicine research.

Near-infrared optical nanothermometry via upconversion of Ho3+-sensitized nanoparticles.

Recently, materials revealing the upconversion (UC) phenomenon, which is a conversion of low-energy photons to higher-energy ones, have attracted considerable attention in luminescence thermometry due to the possibility of precise and remote optical thermal sensing. The most widely studied type of luminescent thermometry uses a ratiometric approach based on changes in the UC luminescence intensity, mainly of lanthanide ions' thermally coupled energy levels. In this work, NaYF4:Ho3+@NaYF4, and NaYF4:Ho3+, Er3+@NaYF4 nanoparticles (NPs) were synthesized by the controlled reaction in oleic acid and octadecene at 573 K. The obtained nanoparticles had hexagonal structures, oval shapes, and average sizes of 22.5 ± 2.2 nm and 22.2 ± 2.0 nm, respectively. The spectroscopic properties of the products were investigated by measurements of the UC emission under 1151 nm laser excitation in the temperature range between 295 to 378 K. The sample doped with Ho3+ and Er3+ ions showed unique behavior of enhancing emission intensity with the temperature. The relative sensitivity determined for the NPs containing Ho3+ and Er3+ ions, reached the maximum value of 1.80%/K at 378 K. Here, we prove that the NaYF4:Ho3+, Er3+@NaYF4 system presents unique and excellent optical temperature sensing properties based on the luminescence intensity ratios of the near-infrared bands of both Ho3+ and Er3+ ions.

The chameleon effect in customer relationship management: Experiments on the spillover effects of mimicry in natural settings of a chain hotel and a chain grocery shop.

Numerous experiments have proven that mimicry is highly beneficial (mainly to the mimicker but also to the mimickee). Some studies have shown initial data suggesting the potential of applying this knowledge to business settings. In the present paper we unpack this issue in two ways. First, by presenting potential benefits stemming from mimicry for the mimicking dyad, and second for the business environment represented by the mimicker. Two consecutive studies: a Pretest and a Main Experiment run in natural settings showed great potential in improving the assessments of quality of service provided by verbally mimicking (or not). The results of both studies showed that mimicry offers benefits for the mimicker (increased employee kindness and employee evaluation), and also spillover to the organization/company represented by the mimicking employee (increased opinion of and willingness to return to the shop/hotel). Future research directions and limitations are discussed.

Ecotoxicity of non- and PEG-modified lanthanide-doped nanoparticles in aquatic organisms.

Various types of nanoparticles (NPs) have been widely investigated recently and applied in areas such as industry, the energy sector, and medicine, presenting the risk of their release into the environment. The ecotoxicity of NPs depends on several factors such as their shape and surface chemistry. Polyethylene glycol (PEG) is one of the most often used compounds for functionalisation of NP surfaces, and its presence on the surfaces of NPs may affect their ecotoxicity. Therefore, the present study aimed to assess the influence of PEG modification on the toxicity of NPs. As biological model, we chose freshwater microalgae, a macrophyte and invertebrates, which to a considerable extent enable the assessment of the harmfulness of NPs to freshwater biota. SrF2:Yb3+,Er3+ NPs were used to represent the broad group of up-converting NPs, which have been intensively investigated for medical applications. We quantified the effects of the NPs on five freshwater species representing three trophic levels: the green microalgae Raphidocelis subcapitata and Chlorella vulgaris, the macrophyte Lemna minor, the cladoceran Daphnia magna and the cnidarian Hydra viridissima. Overall, H. viridissima was the most sensitive species to NPs, which affected its survival and feeding rate. In this case, PEG-modified NPs were slightly more toxic than bare ones (non-significant results). No effects were observed on the other species exposed to the two NPs at the tested concentrations. The tested NPs were successfully imaged in the body of D. magna using confocal microscopy; both NPs were detected in the D. magna gut. The results obtained reveal that SrF2:Yb3+,Er3+ NPs can be toxic to some aquatic species; however, the structures have low toxicity effects for most of the tested species.

Bright photon upconversion in LiYbF4:Tm3+@LiYF4 nanoparticles and their application for singlet oxygen generation and in immunoassay for SARS-CoV-2 nucleoprotein.

Photon upconversion is an intensively investigated phenomenon in the materials sciences due to its unique applications, mainly in biomedicine for disease prevention and treatment. This study reports the synthesis and properties of tetragonal LiYbF4:Tm3+@LiYF4 core@shell nanoparticles (NPs) and their applications. The NPs had sizes ranging from 18.5 to 23.7 nm. As a result of the energy transfer between Yb3+ and Tm3+ ions, the synthesized NPs show intense emission in the ultraviolet (UV) range up to 347 nm under 975 nm excitation. The bright emission in the UV range allows for singlet oxygen generation in the presence of hematoporphyrin on the surface of NPs. Our studies show that irradiation with a 975 nm laser of the functionalized NPs allows for the production of amounts of singlet oxygen easily detectable by Singlet Oxygen Sensor Green. The high emission intensity of NPs at 800 nm allowed the application of the synthesized NPs in an upconversion-linked immunosorbent assay (ULISA) for highly sensitive detection of the nucleoprotein from SARS-CoV-2, the causative agent of Covid-19. This article proves that LiYbF4:Tm3+@LiYF4 core@shell nanoparticles can be perfect alternatives for the most commonly studied upconverting NPs based on the NaYF4 host compound and are good candidates for biomedical applications.

Ultrasensitive optical thermometry using Tb3+ doped NaSrGd(MoO4)3 based on single band ratiometric luminescence.

A lot of people are interested in optical thermometry, especially the new single-band ratiometric (SBR) technology for measuring temperature. But since SBR thermometry is still in its infancy, it is highly constrained when compared to the conventional dual-band ratiometric approach. In this paper, we propose a new SBR thermometry technique that is based on both the ground and excited state absorption processes. When these two different processes occur, the green emission of Tb3+ in the low-cost host of NaSrGd(MoO4)3 (NSGM) responds to changes in temperature in a way that is the exact opposite of what you would expect. The maximum luminescence intensity was obtained for an optimum terbium concentration of 40% mol. The resulting chromaticity coordinates (x, y) and high correlated color temperature (CCT) values of the doped phosphors give a thermally stable cold emission in the green region with a color purity of about 92%. Using this intriguing characteristic as a foundation, sensitive SBR thermometry has been successfully developed, and the optical properties of the material have also been thoroughly researched. At room temperature, the relative sensitivity reaches its maximum value of 10.9% K-1. These findings may give important information that may be used in the design of new luminescent thermometers that have excellent performance.

Introduction to Bacterial Anhydrobiosis: A General Perspective and the Mechanisms of Desiccation-Associated Damage.

Anhydrobiosis is the ability of selected organisms to lose almost all water and enter a state of reversible ametabolism. Such an organism dries up to a state of equilibrium with dry air. Unless special protective mechanisms exist, desiccation leads to damage, mainly to proteins, nucleic acids, and membrane lipids. A short historical outline of research on extreme dehydration of living organisms and the current state of research are presented. Terminological issues are outlined. The role of water in the cell and the mechanisms of damage occurring in the cell under the desiccation stress are briefly discussed. Particular attention was paid to damage to proteins, nucleic acids, and membrane lipids. Understanding the nature of the changes and damage associated with desiccation is essential for the study of desiccation-tolerance mechanisms and application research. Difficulties related to the definition of life and the limits of life in the scientific discussion, caused by the phenomenon of anhydrobiosis, were also indicated.

NIR-to-NIR and NIR-to-Vis up-conversion of SrF2:Ho3+nanoparticles under 1156 nm excitation.

Recently, the up-converting (UC) materials, containing lanthanide ions (Ln3+)have attracted considerable attention because of the multitude of their potential applications. The most frequently investigated are UC systems based on the absorption of near-infrared (NIR) radiation by Yb3+ions at around 975-980 nm and emission of co-dopants, usually Ho3+, Er3+or Tm3+ions. UC can be observed also upon excitation with irradiation with a wavelength different than around 980 nm. The most often studied systems capable of UC without the use of Yb3+ion are those based on the properties of Er3+ions, which show luminescence resulting from the excitation at 808 or 1532 nm. However, also other Ln3+ions are worth attention. Herein, we focus on the investigation of the UC phenomenon in the materials doped with Ho3+ions, which reveal unique optical properties upon the NIR irradiation. The SrF2NPs doped with Ho3+ions in concentrations from 4.9% to 22.5%, were synthesized by using the hydrothermal method. The structural and optical characteristics of the obtained SrF2:Ho3+NPs are presented. The prepared samples had crystalline structure, were built of NPs of round shapes and their sizes ranged from 16.4 to 82.3 nm. The NPs formed stable colloids in water. Under 1156 nm excitation, SrF2:Ho3+NPs showed intense UC emission, wherein the brightest luminescence was recorded for the SrF2:10.0%Ho3+compound. The analysis of the measured lifetime profiles and dependencies of the integral luminescence intensities on the laser energy allowed proposing the mechanism, responsible for the observed UC emission. It is worth mentioning that the described SrF2:Ho3+samples are one of the first materials for which the UC luminescence induced by 1156 nm excitation was obtained.

Improvement in Luminescence Intensity of ß-NaYF4: 18%Yb3+, 2%Er3+@ß-NaYF4 Nanoparticles as a Result of Synthesis in the Presence of Stearic Acid.

The synthesis of upconverting nanoparticles (NPs) is crucial for their spectroscopic properties and further applications. Reducing the size of materials to nano-dimensions usually decreases emission intensity. Therefore, scientists around the world are trying to improve the methods of obtaining NPs to approach levels of emission intensity similar to their bulk counterparts. In this article, the effects of stearic acid on the synthesis of core@shell ß-NaYF4: 18%Yb3+, 2%Er3+@ß-NaYF4 upconverting NPs were thoroughly investigated and presented. Using a mixture of stearic acid (SA) with oleic acid and 1-octadecene as components of the reaction medium leads to the obtaining of monodispersed NPs with enhanced emission intensity when irradiated with 975 nm laser wavelength, as compared with NPs prepared analogously but without SA. This article also reports how the addition of SA influences the structural properties of core@shell NPs and reaction time. The presence of SA in the reaction medium accelerates the growth of NPs in comparison with the analogic reaction but without SA. In addition, transmission electron microscopy studies reveal an additional effect of the presence of SA on the surface of NPs, which is to cause their self-organization due to steric effects.