Photostimulation Research Articles

Sub-cone visual resolution by active, adaptive sampling in the human foveola.

The foveated architecture of the human retina and the eye's mobility enables prime spatial vision, yet the interplay between photoreceptor cell topography and the constant motion of the eye during fixation remains unexplored. With in vivo foveal cone-resolved imaging and simultaneous microscopic photo stimulation, we examined visual acuity in both eyes of 16 participants while precisely recording the stimulus path on the retina. We find that resolution thresholds were correlated with the individual retina's sampling capacity, and exceeded what static sampling limits would predict by 18%, on average. The length and direction of fixational drift motion, previously thought to be primarily random, played a key role in achieving this sub-cone diameter resolution. The oculomotor system finely adjusts drift behavior towards retinal areas with higher cone densities within only a few hundred milliseconds to enhance retinal sampling.

Sub-cone visual resolution by active, adaptive sampling in the human foveola

The foveated architecture of the human retina and the eye’s mobility enables prime spatial vision, yet the interplay between photoreceptor cell topography and the constant motion of the eye during fixation remains unexplored. With in vivo foveal cone-resolved imaging and simultaneous microscopic photo stimulation, we examined visual acuity in both eyes of 16 participants while precisely recording the stimulus path on the retina. We find that resolution thresholds were correlated with the individual retina’s sampling capacity, and exceeded what static sampling limits would predict by 18%, on average. The length and direction of fixational drift motion, previously thought to be primarily random, played a key role in achieving this sub-cone diameter resolution. The oculomotor system finely adjusts drift behavior towards retinal areas with higher cone densities within only a few hundred milliseconds to enhance retinal sampling.

X-ray induced long afterglow luminescence from UVC to red region in Ca2P2O7:Pr3+

In this paper, we developed low dose X-ray induced long afterglow phosphor Ca2P2O7:Pr3+, which shows excellent afterglow luminescence from ultraviolet C (UVC) to red region. The photoluminescent results show that under 445.7 nm excitation, Ca1.995P2O7:0.5%Pr3+ displays red emissions peaked at 598.3 and 651.9 nm, corresponding to 1D2-3H4 and 3P0-3F2 transitions of Pr3+, respectively. Due to its pure red emission (CIE coordinates (0.59101,0.39926)), Ca1.995P2O7:0.5%Pr3+ can be regarded as a potential LED red phosphor. More importantly, Ca2P2O7:Pr3+ shows long afterglow luminescence from UVC to red region, which consists of four continuous emissions with similar intensity including 260, 359, 466 and 598.3 nm. Since these afterglow continuous emissions are fitted to the absorption of most photodynamic therapy (PDT) agents, Ca2P2O7:Pr3+ can be regarded as excellent PDT agents. Furthermore, 30 s X-ray irradiation can induce 5400 s decay of Ca1.997P2O7:0.3%Pr3+, and its afterglow emission intensity still reaches 5×104 cps after 5400 s decay. Even only 5 s X-ray irradiation also can produce 4.75×104 cps afterglow emission after 10 s decay. In addition, the repeat 980 nm laser irradiations can induce continuous strong photo-stimulated (PSL) luminescent peaks, which can be utilized to conduct high efficiency PDT without another X-ray irradiation. The thermoluminescence results reveal that the existence of shallow (0.89 eV) and deep traps are responsible for the excellent X-ray induced long afterglow and PSL luminescence. All these results suggest that Ca2P2O7:Pr3+ possesses great potential to be regarded as high efficiency PDT agents.

N-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan-coated gold nanoparticle-based platform for photothermal/chemo-photodynamic therapy

The combination of photodynamic and photothermal therapy is an interesting strategy for cancer treatment. In this work, we synthesized gold nanoparticles (AuNPs) loaded with methylene blue (MB) and coated with trimethylammonium functionalized chitosan (HTCC). Initially, HTCC was synthesized and characterized by 1H NMR, FTIR and elemental analysis. The degree of substitution (DS) of HTCC of 69 % was obtained through 1H NMR. The formulated HTCC-MB-AuNPs presented strong absorption in the visible range (500–800 nm), a small size of 150 nm, and zeta potential of about + 26 mV. The incorporation of MB in gold nanoparticles coated with HTCC modified the photophysical and photochemical properties, such as a decrease in the intensity of fluorescence emission and a decrease in the reactivity of MB with photo-oxidation model reactions. In vitro testing in MDA-MB231 breast cancer cells showed that HTCC-MB-AuNPs exert significant cytotoxicity in the presence of photo stimulation (red laser, 660 nm, 100 mW cm−2), possibly by combining photothermal and photodynamic effects (PTT + PDT). In the dark, under the same conditions, MB showed less cytotoxicity to cancer cells, especially when encapsulated in HTCC-MB-AuNPs. These results reveal a novel application potential of HTCC-MB-AuNPs in phototherapies for the treatment of cancer.

Sexually inexperienced bucks, photostimulated or not, showed increased plasma testosterone and sexual behaviors with nulliparous and multiparous goats outside of breeding season

The objectives of this study were to determine whether sexually inexperienced photostimulated and nonphotostimulated males had increased plasma testosterone levels and sexual behaviors during their first contact with nulliparous (N) and multiparous (M) females and whether these males could induce sexual responses in females outside of breeding season. Six photostimulated (PH) males were artificially subjected to long days (16 h/light/day/2.5 months), and six nonphotostimulated (NO) males were exposed to the natural photoperiod. Three PH males were exposed to N females (n = 30), and three PH males were exposed to M females (n = 30). Three NO males were exposed to N females (n = 30), and three were exposed to M females (n = 30). In spring (March-April), the males and females remained together for 15 days. The PH males had increased plasma testosterone levels compared to baseline levels during first contact with the N (10.8 ± 2.6 ng/mL) and M females (9.3 ± 1.9 ng/mL) (P < 0.001). Similarly, the NO males had increased plasma testosterone levels during their first contact with N (11.4 ± 1.1 ng/mL) and M females (11.0 ± 0.6 ng/mL) (P < 0.001). Nudging, anogenital sniffing, and mounting attempts varied between the PH and NO males (P < 0.001), whereas mounting with intromission did not differ (P > 0.05). Estrous behavior and ovulation did not differ between N and M females in contact with PH males or between M females in contact with NO males (P > 0.05), whereas the N females in contact with NO males had the lowest response (P < 0.05). We conclude that sexually inexperienced photostimulated and nonphotostimulated males exhibit increased plasma testosterone levels; exhibit sexual behaviors during their first contact with nulliparous and multiparous females; and can stimulate sexual activity in females outside of breeding season.

Biodegradable photo-crosslinked polycaprolactone/polydopamine elastomers with excellent light driven programmable shape memory and chemical degradation properties

Fabrication of biodegradable shape memory polymer with remotely controllable shape actuation is of great significance in the biomedical field but remains challenging. Herein, we present a simple strategy to fabricate a monolayer-based stretchable and mechanically robust polycaprolactone/polydopamine elastomer via efficient thiol-ene click chemistry. The resultant elastomers exhibit desirable photothermal transfer efficiency and can enable rapid temperature increase over the melting temperature of polymeric matrix, and quantitative results demonstrate that the crosslinked film exhibited excellent shape memory properties with shape fixity (Rf) and shape recovery ratios (Rr) approaching 92.3 % and 95.6 %, respectively. Combined with photo stimuli, anisotropic polymer chain relaxation of the prestretched film can generate asymmetric contractions and eventually give rise to ut out-of-plane bending actuations upon photo stimulation, meanwhile, numerical simulation reveals the interaction mechanism of light with film. Beyond this, we further demonstrate that the bending angle is correlated with the parameters of prestretch strain, film thickness as well as irradiation time, and the maximum value can reach 158° with prestretch strain of 200 % and film thickness of 0.3 mm. In particular, the bent structures could be reversibly deformed into plane state via photo-directed corresponding opposite surfaces. Remarkably, the in vitro degradation properties of the elastomers on PBS-T buffer solutions demonstrated that the degradation was composed of induction stage and acceleration stage. This work will pave way for designing biodegradable light-induced shape memory materials toward biomedical device fields and so on.

A study on visual impact assessment of the enclosing wall entourage of Chinese traditional private garden

The enclosing wall is one of the key elements for traditional Chinese private garden. Its entourages are of great historical and cultural values, exerting a significant impact on the life quality of tourists, and especially urban residents. With the enclosing wall entourage of traditional Chinese private garden as research object, this study explored the influence of five landscape elements on respondents' visual impact assessment. The five landscape elements involved in this study were as follows: the number of plant species, the vertical structure of plants, the shielding factor, window, and stone. Three demographic variables, specifically gender, age, and education level, were taken into account as factors for the participants in this study. This study conducted a questionnaire survey, surveyed 339 citizens, and collected a total of 301 valid questionnaires. The analysis of how five distinct landscape elements affect participants' assessments of visual impact was conducted using a photo stimulation method. The findings demonstrate that each of the five landscape elements indeed influences participants' evaluations of visual impact. To be specific, the enclosing wall that wins great popularity among the respondents is featured with the following landscape elements: rich plant species, a vertical structure with three heights of plants, a medium shielding factor, a window on it, and the application of stone. Simultaneously, Chinese residents exhibiting diverse demographic attributes also yield varying assessments of visual impact concerning the distinct landscape elements within the enclosing wall surroundings.

A study on the demographic differences in visual impact assessments of the external space of electric vehicle battery swapping stations

The construction of electric vehicle (EV) battery swapping stations (BSS), which exerts an increasingly significant impact on urban landscapes. In addition, the external space of BSS is an important means to display corporate image and brand publicity. In this experiment, a sample of nine representative BSS in China, characterized by diverse architectural forms, was selected for the examination of their exterior spaces. The study focused on the physical factors of the BSS, specifically the exterior contour, number and position of entrances, façade material, height-width ratio of front elevation, logo area ratio, and hue as key factors under investigation. Meanwhile, five demographic features, namely, gender, age, education level, EV owner or potential owner, and income level, were set as variables to study the influence of the six physical factors of external space on people's visual impact assessment. The photo stimulation method was used in this experiment. The results show that the above six physical factors affect people's visual impact assessment of the external space of BSS, and people with different demographic features render different visual impact assessments. Therefore, we propose several design recommendations for BSS exterior spaces. In BSS exterior space design, greater consideration should be given to using vertical facade aspect ratios between 1/3 and 1/2, facades combining metal and glass, smaller logo area proportions, and designs combining warm and neutral color tones to meet the visual preferences of a broader audience. Different exterior design schemes should also be adopted when BSSs are targeted at different primary user groups.

Theoretical analysis of phase transition behavior of ALCP/CNT nanocomposites interface by photo and thermal stimulation

Azobenzene-containing liquid crystal polymers (ALCPs) functionalised with carbon nanotubes (CNTs) have enormous potential in intelligent devices and soft robotics. This study investigates the phase transition and subcontinuum mechanics occurring at the ALCP/CNT interface under heat and light stimulation using all-atom molecular dynamics (MD) simulations. The results suggest that the strong π-π interaction between azobenzene and CNT directly affects the mechanical behavior due to extremely high interfacial stability. The properties at the interface remain intact even in environments where forced phase transitions are induced by external stimuli. The unique edge-to-face stacking of interfacial azobenzene during isomerization, as well as the co-alignment properties of trans-azobenzene with CNTs in the interfacial region, are the origins of its high stability. The influence of the structural features of the interface on the mechanical behavior during the phase transition is also understood as the load transfer efficiency of each molecular component.

Influencing Factors in Visual Preference Assessment of Redeveloped Urban Villages in China: A Case Study of Guangdong Province

The urban village represents a particular problem in urban design and renewal in China. Many cities in China have started the redevelopment of urban villages. Based on the investigation of four urban village redevelopment projects in Guangdong Province, China from 2010 to 2020, building façades, plant landscape, roads, and municipal public facility variety were taken as physical factors in this study. Urban village residents with different demographic characteristics, such as gender, age, income, family size, and urban village-native status, were selected as respondents, and the influence of the considered village physical factors on the visual preference assessments performed by the respondents was analyzed by means of photo stimulation. The results show that all four village factors exerted a certain influence on the respondents’ visual preference assessment. Redeveloped urban villages presenting repaired and decorated building façades, various species of plants, resurfaced roads, and medium municipal public facility variety were favored by the respondents. Urban village residents with different demographic characteristics also provided different visual preference assessments of different physical factors of the redeveloped urban villages.

Competent production of hydrogen and hydrogenation of carboxylic acids using urea-rich waste water over visible-light-responsive rare earth doped photocatalyst

BackgroundA strategy employing water as a hydrogen source is promising but challenging. Conversely, urea is the major pollutants causing substantial water pollution. Moreover, direct reduction of carboxylic acids into aldehydes is still a great challenge due to higher propensity of aldehydes being further reduced to alcohols. MethodsWe report a visible-light driven one-step protocol to selectively convert aromatic carboxylic acids to aldehydes with water as the sustainable hydrogen source, environmental pollutant urea as a hole scavenger and Eu3+ doped Na2CaP2O7 phosphor as a viable photocatalyst. Significant findingsApart from the photocatalytic H2 evolution, the procedure is able to reduce a broad range of carboxylic substrates with good functional group tolerance in good to excellent yield. The insertion of Eu3+ into the present host creates several metastable states inside the forbidden region and thereby led to enhancement of photo stimulation process. Moreover, various experiments and analytical analysis reveal that photo-generated active H-species from water are the direct reducing agent, skipping the use of traditional flammable H2. Present work provides a ‘waste-to-value’ route for solar energy driven preparation of valuable chemicals by simultaneous photocatalytic treatment of urea-rich waste water.

Investigating the Modulation of the VTA Neurons in Nicotine-Exposed Pups during Early Maturation Using Optogenetics.

Advancing the understanding of the relationship between perinatal nicotine addiction and the reward mechanism of the brain is crucial for uncovering and implementing new treatments for addiction control and prevention. The mesolimbic pathway of the brain, also known as the reward pathway, consists of two main areas that regulate dopamine (DA) and addiction-related behaviors. The ventral tegmental area (VTA) releases DA when stimulated, causing the propagation of neuronal firing along the pathway. This ends in the release of DA into the extracellular space of the nucleus accumbens (NAc), which is directly modulated by the uptake of DA. Much research has been conducted on the effects of nicotine addiction, but little research has been conducted concerning nicotine addiction and the mesolimbic pathway regarding maturation due to the small brain size. In this study, we apply our novel microstimulation experimental system to rat pups that have been perinatally exposed to nicotine. By using our self-fabricated photo-stimulation (PS) device, we can stimulate the VTA and collect dialysate, which is then used to estimate DA released into the NAc. The proposed platform has demonstrated the potential to monitor neural pathways as the pups mature.

PHOTOBIOMODULATION IN DENTISTRY: A REVIEW OF THE LITERATURE

Photobiomodulation therapy (PBMT), is the ability to modulate cell growth, survival, and differentiation processes of cells using optimal amount of energy ,not causing phototoxicity . It includes a wide range of electromagnetic wavelengths such as broadband lights, LEDs, and lasers that may have both photo stimulation and photo inhibitory effects on the target tissues, each of which can be used in therapeutic applications. Some of the benets of using PBMTin dentistry include reducing dentin sensitivity to tactile and thermal stimulations, improving dentin formation from dental pulp, reducing inammation of oral mucosa, accelerating bone formation, reducing pain after all types of dental treatments, and improving wound healing processes. In this review of literature, we emphasize that PBMT itself or as an adjunct can have a crucial role in decreasing postoperative dental pain, increasing depth of anesthesia during cavity preparation, decreasing tooth hypersensitivity, reducing inammation of the tissues, and healing of denture stomatiti

Mechanisms of Photostimulation of Brain's Waste Disposal System: The Role of Singlet Oxygen.

There is strong evidence that augmentation of the brain's waste disposal system via stimulation of the meningeal lymphatics might be a promising therapeutic target for preventing neurological diseases. In our previous studies, we demonstrated activation of the brain's waste disposal system using transcranial photostimulation (PS) with a laser 1267nm, which stimulates the direct generation of singlet oxygen in the brain tissues. Here we investigate the mechanisms underlying this phenomenon. Our results clearly demonstrate that PS-mediated stimulation of the brain's waste disposal system is accompanied by activation of lymphatic contractility associated with subsequent intracellular production of the reactive oxygen species and the nitric oxide underlying lymphatic relaxation. Thus, PS stimulates the brain's waste disposal system by influencing the mechanisms of regulation of lymphatic pumping.

Visual appraisal of designed landscapes in high-rise residential areas rendered by residents living at different heights

As residential buildings become higher and higher, people begin to pay more attention to the views they can see through windows. Currently, the studies on landscape are mostly conducted at the height of human eye level, and little has been done on visual impact assessment of landscapes from other height perspectives. This study divided the high-rise residential buildings into different height partitions and set landscape style, green area, number of colors, water features, and vertical structure as landscape features. Then the residents living in different height partitions were surveyed by photo stimulation experiments and the data were collected and analyzed. The results show that the five features mentioned above are the main influencing factors for the respondents’ visual impact assessment; residents living in different height partitions rendered different visual impact assessments of the landscapes in residential areas; different landscape features exert certain influence upon the residents living.

Research on Visual Preference of Chinese Courthouse Architecture Appearance

Whether courthouse architecture should be solemn or friendly is a topic worth exploring. Currently, a large quantity of courthouse buildings have been constructed in China, but the architectural style differs greatly. This situation provides a good foundation for the study on visual preference appraisal of the external form of courthouse buildings. This research selected 50 representative courthouse buildings as the research object and set architectural style, height–width ratio, window–wall ratio, and open ground in front of the buildings as the physical properties under study. Participants of different demographic characteristics were chosen to conduct a photo stimulation experiment. The results obtained were analyzed by SPSS. According to the research results, the neoclassical courthouse building with a large window–wall ratio, small height–width ratio, and large open ground is the most favorite among the participants; participants of different demographic characteristics render different visual preference appraisals of the external form of Chinese courthouse buildings. Contemporary Chinese court building should have a new image. This research can be taken as a reference for the external design of Chinese courthouse buildings.

Endophytic, Non-endophytic Fungal Alkaloids and its Applications

Alkaloids are a secondary metabolite, which are extracted from a wide – array of organisms include Bacteria, Fungi, Plants and Animals. Here in present review mainly focused on the alkaloids derived from endophytic fungi and non – endophytic fungi. Fungi have provided a great source of spirit for novel drug compounds as fungi derived alkaloids have done major boon to human health and well - being. In the present review listed 35 different group of alkaloids from endophytes. In which 12 different alkaloids are kept under derivatives of Indole group, 4 different alkaloids are kept under Quinoline group, 4 different alkaloids kept under amines and amide group, from non-endophytic alkaloid 27 different group of alkaloids are reported. In which 9 different type of alkaloid are mentioned under indole group of alkaloids, 4 alkaloids are reported under diketopiperazine alkaloids, 4 different alkaloids are mentioned under ergot group of alkaloids, 3 alkaloids under prenylated indole alkaloids, 3 alkaloids are mentioned under pyridine classes. The main applications of these alkaloids are antimicrobial, Antibacterial, Antifungal, Antiviral Activity Antihelmenthic, Anticancerous, Nutrient Pedaling, Photo stimulation, Endophytes in Tissue Culture Antidiabetic Activity, and Immunosuppressive Activity; hence all the alkaloids should be used as medicines in Ayurvedam. The alkaloids derived from different fungi were reviewed and their uses in medical fields were also report.

Night Photostimulation of Clearance of Beta-Amyloid from Mouse Brain: New Strategies in Preventing Alzheimer's Disease.

The deposition of amyloid-β (Aβ) in the brain is a risk factor for Alzheimer’s disease (AD). Therefore, new strategies for the stimulation of Aβ clearance from the brain can be useful in preventing AD. Transcranial photostimulation (PS) is considered a promising method for AD therapy. In our previous studies, we clearly demonstrated the PS-mediated stimulation of lymphatic clearing functions, including Aβ removal from the brain. There is increasing evidence that sleep plays an important role in Aβ clearance. Here, we tested our hypothesis that PS at night can stimulate Aβ clearance from the brain more effectively than PS during the day. Our results on healthy mice show that Aβ clearance from the brain occurs faster at night than during wakefulness. The PS course at night improves memory and reduces Aβ accumulation in the brain of AD mice more effectively than the PS course during the day. Our results suggest that night PS is a more promising candidate as an effective method in preventing AD than daytime PS. These data are an important informative platform for the development of new noninvasive and nonpharmacological technologies for AD therapy as well as for preventing Aβ accumulation in the brain of people with disorder of Aβ metabolism, sleep deficit, elderly age, and jet lag.

A study on visual impact assessment of the external form of unified houses in rural China

ABSTRACT Under the background of promoting rural revitalization in China, the construction of unified houses has become an important trend of rural development. However, controversy has never ceased over its results. This research set the external form of unified houses as its research object and surveyed forty-two rural unified housing programs distributed in Jiangsu, Zhejiang, and Shandong provinces. Five physical features (namely, building stories, roof type, courtyard area, window-wall ratio, and residential landscape area) were taken as the research dimensions to evaluate the influence of these features on respondents’ visual impact assessment by means of photo stimulation. Through analyzing the data obtained from experiments, the difference of rural families with different demographic characteristics in their visual impact assessment has been explored. The results show that all the five physical features would influence rural residents’ visual impact assessment of the external form of unified house; families with different demographic characteristics also differ in their visual impact assessment. This research provides constructive reference for the better development of unified housing program in rural China.

Photo Stimulation of Seminal Doses with Red LED Light from Duroc Boars and Resultant Fertility in Iberian Sows

Simple SummaryThe main objective of breeding Iberian pigs is the production of high-quality dry cured meat products. As this breed shows a reduced litter size in comparison to the commercial breeds, some previous studies have reported the use of photostimulation of seminal doses as a method for improving the farrowing rate and litter size. The aim of this study was to explore whether the application of a photostimulation procedure to Duroc seminal doses has any beneficial effect on fertility and litter size. Semen samples were obtained from 38 fertile Duroc boars and the fertility study was conducted on two commercial farms using multiparous Iberian sows (farm A, n = 824; farm B, n = 2131), that were randomly assigned to LED (L) or control (C) groups. Post-cervical insemination took place 0 and 24 h after the diagnosis of estrus, with seminal doses from the same ejaculate and same treatment. The photostimulation of the seminal doses had no effect on the reproductive performance (farrowing rate: 91.72% C vs. 90.09% L, litter size: 8.71 ± 0.06 piglets C vs. 8.70 ± 0.05 L, p > 0.05).In pigs, it has been reported that increased farrowing rates and litter size have been induced by photostimulating the seminal doses for artificial insemination with red LED light. As the reproductive characteristics, production system, and outcome parameters of Iberian breed pigs are different from other commercial breeds, the aim of this study was to evaluate the possible effect of illuminating seminal doses from Duroc boars with red LED light and the fertility outcomes of Iberian females. Semen samples were obtained from 38 fertile Duroc boars. Photostimulation of the artificial insemination (AI) seminal doses was carried out by illuminating the samples with a red LED for 10 min, followed by 10 min of darkness, and finally 10 additional minutes of red light. The fertility study was conducted on two commercial farms using multiparous Iberian sows (farm A, n = 824; farm B, n = 2131), that were randomly assigned to LED (L) or control (C) groups. No differences were found between L and C groups in both farms (p > 0.05) for parity, pregnancy rate, duration of pregnancy, farrowing rate, and litter size (total, alive, and stillborn piglets). Farrowing rates in farm A were 88.8% (n = 383) for control and 89.6% (n = 441, p = 0.67) for the LED group. In farm B, farrowing rates were C:90.5% (n = 1030) and L: 90.1% (n = 1101, p = 0.48). In farm A, total born piglets were 8.69 ± 0.11 for C and 8.71 ± 0.11 for L (p = 0.87). In farm B, the results were 8.72 ± 0.7 for C and 8.70 ± 0.06 (p = 0.82) for L. Under the production conditions for the Iberian breed, the photostimulation with red LED light using Duroc pig seminal doses was not effective in improving the fertility of Iberian sows.