Demographic feedbacks can hamper the spatial spread of a gene drive

This paper is concerned with a reactionddiffusion system modeling the fixation and the invasion in a population of a gene drive (an allele biasing inheritance, increasing its own transmission to offspring). In our model, the gene drive has a negative effect on the fitness of individuals carrying it, and is therefore susceptible of decreasing the total carrying capacity of the population locally in space. This tends to generate an opposing demographic advection that the gene drive has to overcome in order to invade. While previous reaction-diffusion models neglected this aspect, here we focus on it and try to predict the sign of the traveling wave speed. It turns out to be an analytical challenge, only partial results being within reach, and we complete our theoretical analysis by numerical simulations. Our results indicate that taking into account the interplay between population dynamics and population genetics might actually be crucial, as it can effectively reverse the direction of the invasion and lead to failure. Our findings can be extended to other bistable systems, such as the spread of cytoplasmic incompatibilities caused by Wolbachia.

Role of Na-Montmorillonite on Microbially Induced Calcium Carbonate Precipitation

The use of additives has generated significant attention due to their extensive application in the microbially induced calcium carbonate precipitation (MICP) process. This study aims to discuss the effects of Na-montmorillonite (Na-MMT) on CaCO3 crystallization and sandy soil consolidation through the MICP process. Compared with the traditional MICP method, a larger amount of CaCO3 precipitate was obtained. Moreover, the reaction of Ca2+ ions was accelerated, and bacteria were absorbed by a small amount of Na-MMT. Meanwhile, an increase in the total cementing solution (TCS) was not conducive to the previous reaction. This problem was solved by conducting the reaction with Na-MMT. The polymorphs and morphologies of the CaCO3 precipitates were tested by using X-ray diffraction and scanning electron microscopy. Further, when Na-MMT was used, the morphology of CaCO3 changed from an individual precipitate to agglomerations of the precipitate. Compared to the experiments without Na-MMT in the MICP process, the addition of Na-MMT significantly reduced the hydraulic conductivity (HC) of sandy soil consolidated.

Reforms Reaffirmed to Improve International Surveillance and Response Mechanism in WHO in the Post-Coronavirus Situation

The emergence of COVID–19 has shown that the inability of WHO to have prompt disease surveillance could be callous to recognize and respond to the situation of Public Health Emergency of International Concern (PHEIC). While the paper traces out the timeline of WHO to perform its mandate in combating the spread of infectious diseases, coincidently it also explains the needs to improve the epidemic intelligence on the basis of coordinated international and national surveillance and response mechanisms. On the note, the post COVID – 19 situation requires WHO member states to strengthen the institution within the international order of global health governance. The only way to do so will be through effective and prompt global disease surveillance and response systems. Further, the article attempts to shed light on the current and previous reaction of WHO over the infectious diseases including COVID – 19. In the process, this article tries to suggest reforms within the IHR and WHO’s applicable effort to develop effective disease surveillance and prompt response systems.

Study on the phase evolution and element migration of vanadium oxide during the nitridation process

In this paper, a series of nitriding experiments were carried out to investigate the phase evolution and element migration in the nitriding process. The results show that it undergoes a low temperature reducing stage firstly. High valent vanadium oxides are reduced to V2O3 between room temperature and 770 °C. In Ar atmosphere, V2O3 reacts with C to form VC in the temperature interval of 770 °C∼1080 °C. In N2 atmosphere, V2O3 reacts directly with N2 and C to form VN in the interval of 670 °C∼1050 °C. During 1050 °C∼1270 °C, part of the VN obtained in the previous reaction stage will react with C to form VC. High temperature is beneficial to the removal of impurity element sulfur. The volatilization of alkali metal elements in the pellet mainly occurs between 670 °C and 1270 °C. However, there are about 20% of sodium and potassium remain in the nitriding product. The volatile alkali metal vapor would react with other gases at the furnace cover to form a white sediment and deposits on the cover. The sediment mainly consists of Na2CO3, K2CO3, Na2SO4, K2SO4, KCl, etc.

Synthesis, Characterization and Cytotoxic Activity of some new 1,2,3-Triazole, Oxadiazole and Aza- β-lactam Derivatives

A series of 1,2,3-triazole, oxadiazole and aza-β-lactam derivatives were synthesized through consecutive reaction began from o-(N-propargyl) sulfonamido benzoic acid (1a). The reaction of (1a) with absolute ethanol in the presence of concentrated H2SO4 resulted in the formation of ester derivative (2a). The product of the previous reaction was reacted with 80% hydrazine hydrate to prepare benzohydrazide derivative (3a). 1,3,4-oxadiazole compound (4a) was obtained by condensation of compound (3a) with CS2 in presence KOH . Compound (3a) react with Phenyl isocyanates to give Carboxamide derivative (5a), that Condensation either with 2,4-dimethoxybenzaldhyde and p-hydroxybenzaldehyde to prepare the Schiff bases (6a-b). The cycloaddotion of Schiff-bases (6a-b) with phenyl isocyanate gave aza-β-lactams (7a-b). Benzamide derivatives (8a-c) were prepared via the reaction of compound (1a) with aniline derivatives, such as (p-toluidine, o-nitroaniline and m-nitroaniline). In a regioselective reaction 1,4-disubstituted-1,2,3-triazole derivative (9a-j) were synthesized via the click reaction of compounds 4a,5a and (8a-c) with benzyl azide and p-bromobenzyl azide. The compounds were identified using the spectral methods shown in the work. Cytotoxic effects of some final prepared compounds were studied in one cultured cellular models (MCF7 cell line) breast cancer (at various concentrations) by MTT assay, compound (9j) showed the better cytotoxic activity among the tested compounds.

Indium-Catalyzed Direct Conversion of Lactones into Thiolactones Using a Disilathiane as a Sulfur Source

Indium-catalyzed reaction of lactones and a disilathiane leading to thiolactones is described. The direct synthesis of thiolactones from lactones with an appropriate sulfur source is one of the most attractive approaches in organic and pharmaceutical chemistry. In this context, we found an indium-catalyzed direct conversion of lactones into thiolactones in the presence of elemental sulfur and a hydrosilane via formation of the disilathiane in-situ. On the basis of the previous reaction, the application utilizing the disilathiane as a sulfur source was performed herein for the efficient synthesis of a variety of thiolactone derivatives from lactones by an indium-catalyst.

On a procedure error in the free associations experiment

The paper discusses the risks of distortion of the results of a free associative experiment due to the essence of its procedure. The matter is that the “canonical” experiment’s instruction urges the participants to produce and write down at least three reactions to the proposed stimulus. It doesn’t consider the risk that each subsequent reaction, the second and/or the third one, may be induced not by the initial stimulus, but by the previous reaction which thus may also act like an occasional unintentional stimulus because not intended by the researcher. Theoretically, there a risk that the obtained data might distort real connections between the intended stimulus and respondents’ reactions in the participants’ mental lexicon. But in reality the impact of such a distortion is not of major importance: the analysis of 6782 "stimulus — reaction (1, 2 or 3 reactions)" pairs shows that the number of cases where the described shift occurs is not statistically significant. The number of erroneous reactions which are obviously induced by the procedure flaw itself (that is, each of the following is given to the previous one, rather than to the stimulus) amounts to no more than 1% of the total number of reactions. Therefore, such an error can’t be considered as regular and must be referred to as insignificant. It’s clear now that cases where each reaction of the three is associated with the initial (intended) stimulus or each of the following reactions refers to the "stimulus + first reaction" complex largely predominate. At the same time, as it was argued long before by Sechenov, Polivanov, Fortunatov, and Kruchevsky ( Kruszewski), verbal associating is a random (stochastic) process, which means that a large majority of reactions’ meanings are unpredictable. On these grounds the author concludes that this is due to the peculiarities of the individual’s mental lexicon which is the product of their minds and consciousness. The way of their exteriorization must also be taken into account. When, triggered by the stimulus, the process of associating starts, a huge number of reactions is activated at the same time in the human brain, but their writing down can take place only sequentially. Thus, the linear character of writing may become partly responsible for an erroneous shift of the stimulus.

Crystal structure of 2-chloro-1,3-(2,6-diisopropylphenyl)-4,5-dihydro-1H-imidazol-3-ium tetrakis(3,5-trifluoromethylphenyl)borate

The title compound, C27H38ClN2+·C32H12BF24−, was synthesized by reacting the product formed from a previous reaction between 1,3-bis(2,6-diisopropylphenyl)imidazolinium-2-carboxylate (SIPrCO2), and SOCl2, with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF). In the cation, the imidazole ring is in a half-chair conformation and the formerly carbene carbon atom is bonded in a distorted trigonal–planar geometry with N—C—Cl angles of 122.96 (16) and 122.21 (16)° and an N—C—N angle of 114.83 (18)°. In the crystal, weak C—H...F hydrogen bonds link the cations and anions, forming a three-dimensional network. In addition, a short Cl...F contact of 3.213 Å and several short F...F contacts less than the sum of the van der Waals radii [1.47 Å + 1.47 Å = 2.94 Å] are observed. The F atoms of two of the CF3groups were refined as disordered over four sets of sites.

The effect of task-irrelevant stimulus ‘graspability’ on reaching actions

Reaching and grasping requires integration of visual, proprioceptive and somatosensory inputs. Previous research has shown that manipulating the ‘graspabilty’ of a visual stimulus influences reaction times to that stimulus (e.g., Tucker and Ellis, 1998). Here we explored whether this same effect can be extended to the planning and online control of arm movements. Participants made a mimed reaching movement with their left or right hand depending on the colour of images of affordance (door handles) and control stimuli (a row of dots of similar size and orientation as the door handle). Stimulus onset was manipulated by changing when the grey stimulus changed colour. Stimuli either pointed towards (compatible) or pointed away from (incompatible) the responding hand. Spatially compatible affordance stimuli facilitated reach onset compared to other stimuli and compatibility combinations, replicating previous reaction time studies. This can be attributed to a priming of the motor system by spatially compatible affording items. Results also indicated a larger outwards deviation of reach trajectory for spatially incompatible control stimuli compared to spatially compatible control stimuli, which waned with stimulus onset delay. This reveals an immediate inhibitory effect on reach trajectory, such that outwards movement is over-compensated to negate this incompatible orientation. Overall, we observed that the effect of visual spatial compatibility on reach kinematics differs with the action relevance of the stimulus. We are currently exploring how this multisensory visuomotor effect changes with age.

Coactive Processing of Dimensionally Redundant Targets Within the Auditory Modality?

Previous reaction time studies have demonstrated coactivation processes within the visual modality for redundant stimuli that differ in two dimensions (e.g., shape and color). The present study provides novel results of analogous processes within the auditory modality. A redundant-target effect (RTE) was obtained in a Go/NoGo experiment using tones that differed in location and/or frequency. Participants were asked to respond to a specific tone location (e.g., left) and/or tone frequency (e.g., 200 Hz) of auditory stimuli. For redundant targets (e.g., a 200 Hz tone presented to the left), an RTE was observed which was too large to be explained by mere statistical facilitation. Therefore, responses to redundant targets were triggered by a combined activation of the target dimensions. The results are consistent with the modular hybrid account of Mordkoff and Yantis (1993) .