Online photography intervention reduces internet addiction during COVID-19: A randomised controlled trial.

The COVID-19 pandemic has escalated concerns regarding internet addiction. This study investigated the impact of an online photograph intervention on internet addiction and identified its effectiveness mechanisms. Individuals diagnosed with internet addiction (internet addiction test score > 36, Mage = 22.85, 78.6% women) were randomly allocated to either the intervention (n = 64) or control (n = 81) groups. For 10 days, the intervention group was tasked with photographing "things that make you feel a sense of control in life" and writing 100-word descriptions explaining the reason for the sense of control elicited by the image. Meanwhile, the control group participated only in the assessments. Assessments were conducted before the intervention, immediately afterward and 7 days later. A significant interaction between group and time was observed, with the intervention group showing a notable reduction in internet addiction and an increase in sense of control. The sense of control at post-test significantly mediated the intervention's effect on reducing internet addiction at follow-up, but only among individuals with high perceived social support. The findings indicate that online photography interventions can effectively diminish internet addiction, with a sense of control acting as a potent mechanism for intervention, particularly in individuals with substantial perceived social support.

The Relationship Between Meaning in Life and Health Behaviors in Adults Aged 55 Years and Over During the COVID-19 Pandemic: the Mediating Role of Risk Perception and the Moderating Role of Powerful Others Health Locus of Control.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has impacted many people's meaning in life and health behaviors. This study aimed to verify the relationship among meaning in life (MIL), epidemic risk perception, health locus of control (HLC), and preventive health behaviors among older adults after the COVID-19 outbreak was declared a pandemic. METHOD: In this longitudinal study, 164 participants aged 55 years and above completed the following measures at time 1 (February 19, 2021) and one month later at time 2 (March 19, 2021): Meaning in Life in the Epidemic Questionnaire, Epidemic Risk Perception Questionnaire, Multidimensional Health Locus of Control Scale, and Health Behaviors Before and After the Epidemic Survey. Hayes' SPSS Process Macro was used to analyze the mediating effect of epidemic risk perception (model 4) and the moderating role of powerful others HLC in the mediation model (model 14). RESULTS: The results showed that after controlling for gender, age, education level, and health behaviors at the baseline, risk perception had a significant mediating effect on the relationship between MIL and preventive health behaviors (ß = .02, SE = .01, 95% CI [.00, .04]). In addition, powerful others HLC had a moderating effect on the second half of the mediating effect (ß = .02, p = .02, 95% CI [.00, .03]). Specifically, compared to the older adults with low powerful others HLC, the risk perception of older adults with high powerful others HLC increased preventive health behaviors. CONCLUSION: Practitioners should adequately cultivate older adults' risk awareness and reinforce the importance of advice from doctors and professionals, thereby effectively enhancing the preventive health behaviors of older adults in China during the COVID-19 pandemic.

Multivalent Cations Reverse the Twist-Stretch Coupling of RNA.

When stretched, both DNA and RNA duplexes change their twist angles through twist-stretch coupling. The coupling is negative for DNA but positive for RNA, which is not yet completely understood. Here, our magnetic tweezers experiments show that the coupling of RNA reverses from positive to negative by multivalent cations. Combining with the previously reported tension-induced negative-to-positive coupling reversal of DNA, we propose a unified mechanism of the couplings of both RNA and DNA based on molecular dynamics simulations. Two deformation pathways are competing when stretched: shrinking the radius causes positive couplings but widening the major groove causes negative couplings. For RNA whose major groove is clamped by multivalent cations and canonical DNA, their radii shrink when stretched, thus exhibiting positive couplings. For elongated DNA whose radius already shrinks to the minimum and canonical RNA, their major grooves are widened when stretched, thus exhibiting negative couplings.

Multivalent Ion-Mediated Attraction between Like-Charged Colloidal Particles: Nonmonotonic Dependence on the Particle Charge.

Ion-mediated effective interactions are important for the structure and stability of charged particles such as colloids and nucleic acids. It has been known that the intrinsic electrostatic repulsion between like-charged particles can be modulated into effective attraction by multivalent ions. In this work, we examined the dependence of multivalent ion-mediated attraction between like-charged colloidal particles on the particle charge in a wide range by extensive Monte Carlo simulations. Our calculations show that for both divalent and trivalent salts, the effective attraction between like-charged colloidal particles becomes stronger with the increase of the particle charge, whereas it gradually becomes weakened when the particle charge exceeds a "critical" value. Correspondingly, as the particle charge is increased, the driving force for such effective attraction transits from an attractive electrostatic force to an attractive depletion force, and the attraction weakening by high particle charges is attributed to the transition of electrostatic force from attraction to repulsion. Our analyses suggest that the attractive depletion force and the repulsive electrostatic force at high particle charges result from the Coulomb depletion which suppresses the counterion condensation in the limited region between two like-charged colloidal particles. Moreover, our extensive calculations indicate that the "critical" particle charge decreases apparently for larger ions and smaller colloidal particles due to stronger Coulomb depletion and decreases slightly at higher salt concentrations due to the slightly enhanced Coulomb depletion in the intervening space between colloidal particles. Encouragingly, we derived an analytical formula for the "critical" particle charge based on the Lindemann melting law.

Cytosine Methylation Enhances DNA Condensation Revealed by Equilibrium Measurements Using Magnetic Tweezers.

CpG methylation of DNA is common in mammalian cells. In sperm, the DNA has the highest level of CpG methylation and is condensed into toroidal structures. How CpG methylation affects DNA structures and interactions is important to understand its biological roles but is largely unknown. Using an RNA-DNA-RNA structure, we observed the equilibrium hopping dynamics between the condensed and extended states of DNA in the presence of polyamines or polylysine peptide as a reduced model of histone tails. Combing with the measured DNA elasticities, we report that CpG methylation of each cytosine nucleotide substantially increases DNA-DNA attraction by up to 0.2 kBT. For the DNA with 57% GC content, the relative increase caused by CpG methylation is up to 32% for the spermine-induced DNA-DNA attraction and up to 9% for the polylysine-induced DNA-DNA attraction. These findings help us to evaluate the energetic contributions of CpG methylation in sperm development and chromatin regulation.

Opposite Effects of High-Valent Cations on the Elasticities of DNA and RNA Duplexes Revealed by Magnetic Tweezers.

We report that trivalent cobalt hexammine cations decrease the persistence length, stretching modulus, helical density, and size of plectonemes formed under torque of DNA but increase those of RNA. Divalent magnesium cations, however, decrease the persistence lengths, contour lengths, and sizes of plectonemes while increasing the helical densities of both DNA and RNA. The experimental results are explained by different binding modes of the cations on DNA and RNA in our all-atom molecular dynamics simulations. The significant variations of the helical densities and structures of DNA and RNA duplexes induced by high-valent cations may affect interactions of the duplexes with proteins.

Shear-induced microstructures and dynamics processes of phospholipid cylinders in solutions.

Shear-induced microstructures and their corresponding dynamic processes are investigated for phospholipid cylinders in aqueous solution by dissipative particle dynamic simulation. Various phospholipid cylinders with cross-sections, which are formed under shear-free flow, are selected to examine the effects of shear flow on their structures and dynamic processes. Shear flow induces the transition from cylinders into vesicles at weak rate and the transition into vesicle-lamella mixtures with increased shear rate and lamella structures at the strong shear rate. Then, the average radius of gyration and shape factors of the polymer chains in the dynamic processes are discussed in detail. Results show that shear flow causes the structure of the polymer chains to be elongated along the shear direction, and the configuration of the polymer chain can be rapidly transformed into an ellipsoid structure under strong shear.

Apparent repulsion between equally and oppositely charged spherical polyelectrolytes in symmetrical salt solutions.

Ion-mediated interactions are very important for the properties of colloids and biomacromolecules such as nucleic acids and proteins. In this work, the ion-mediated interactions between equally and oppositely charged spherical polyelectrolytes (SPEs) in symmetrical divalent electrolytes have been investigated by Monte Carlo simulations, and an unexpected apparent repulsion was observed at high divalent salt concentration. Our investigations also show that the effective repulsion becomes more pronounced for SPEs with higher charge densities and for counterions with larger sizes and was found to be tightly accompanied with the over-neutralization to SPEs by condensed counterions and their release upon the approach of SPEs. Such attractive interaction can be reproduced by our proposed modified Poisson-Boltzmann model and is mainly attributed to the increase in the electrostatic repulsion between on charged SPE and the over-neutralized counterions around the other oppositely SPE with the approach of the two SPEs.