Hysteretic Piezochromism in a Lead Iodide-Based Two-Dimensional Inorganic-Organic Hybrid Perovskite.

Two-dimensional inorganic-organic hybrid perovskites are in the limelight due to their potential applications in photonics and optoelectronics. They are environmentally stable, and their various chemical compositions offer a wide range of bandgap energies. Alternatively, crystal deformation enables in situ control over their optical properties. Here, we investigate (C6H9C2H4NH3)2PbI4, a hybrid perovskite whose organic linkers are 2-(1-cyclohexenyl)ethylammonium. Pressure-dependent optical absorption and emission spectroscopy reveal a hysteretic piezochromism that was not reported for other lead iodide-based 2D perovskites. We combine our optical studies with high-pressure X-ray diffraction experiments and first-principles calculations to demonstrate that the deformation of the inorganic lead iodide layers is the main reason for the observed changes in the optical bandgap.

Exploring Nanocarriers as Treatment Modalities for Skin Cancer.

Cancer is a progressive disease of multi-factorial origin that has risen worldwide, probably due to changes in lifestyle, food intake, and environmental changes as some of the reasons. Skin cancer can be classified into melanomas from melanocytes and nonmelanoma skin cancer (NMSC) from the epidermally-derived cell. Together it constitutes about 95% of skin cancer. Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (CSCC) are creditworthy of 99% of NMSC due to the limited accessibility of conventional formulations in skin cancer cells of having multiple obstacles in treatment reply to this therapeutic regime. Despite this, it often encounters erratic bioavailability and absorption to the target. Nanoparticles developed through nanotechnology platforms could be the better topical skin cancer therapy option. To improve the topical delivery, the nano-sized delivery system is appropriate as it fuses with the cutaneous layer and fluidized membrane; thus, the deeper penetration of therapeutics could be possible to reach the target spot. This review briefly outlooks the various nanoparticle preparations, i.e., liposomes, niosomes, ethosomes, transferosomes, transethosomes, nanoemulsions, and nanoparticles technologies tested into skin cancer and impede their progress tend to concentrate in the skin layers. Nanocarriers have proved that they can considerably boost medication bioavailability, lowering the frequency of dosage and reducing the toxicity associated with high doses of the medication.

A Comprehensive Review on Novel Pathways in Cancer Treatment: Clinical Applications and Future Prospects.

Cancer is a global health issue that requires ongoing therapeutic advances. This review provides an overview of recent treatment strategies focusing on novel pathways in cancer therapy. Emerging research has unveiled promising targets that go beyond traditional modalities, offering new avenues for precision medicine and improved patient outcomes. One key area of innovation lies in targeted therapies directed at specific molecular pathways implicated in cancer progression. The identification of novel biomarkers has paved the way for the development of precision medicines tailored to individual patient profiles. Immunotherapy has also revolutionised cancer treatment by using the immune system to identify and remove cancer cells. Moreover, advancements in epigenetic therapies and RNA-based interventions demonstrate unprecedented potential in modulating gene expression and disrupting cancer-specific signalling pathways. We have discussed the pathophysiology of cancer, different immune checkpoint inhibitors, and targeted therapies in signalling therapies. The epigenetic modulators, such as Histone deacetylase (HDACs) inhibitors and DNA methyltransferase (DNMT) inhibitors, were studied. Recent breakthroughs in cancer immunotherapy treatment (CAR-T) cell therapy showcase the potential to enhance the immune response against various cancers; thus, related information was incorporated. Further, RNA-based therapies like RNA interference and mRNA-based vaccines and therapies, combination therapies, and novel therapies were discussed in the present article.

Green sustainability in the hotel sector: The role of CSR, intrinsic green motivation, and personal environmental norms.

In the context of the United Nations Sustainable Development Goals (UN-SDGs), this study accentuates the role of the tourism and hospitality sector in promoting sustainability. The primary purpose is to unravel the relationship between corporate social responsibility (CSR) and energy-specific sustainable behavior of employees (ESBE), with particular emphasis on the mediating roles of green intrinsic motivation and personal environmental norms. Utilizing a three-wave data collection approach, we secured 325 valid responses from sector employees at various levels (manager-non managers) and applied Structural Equation Modeling through the SMART-PLS tool to assess the hypothesized relationships. The findings highlight a pronounced interconnection between CSR, ESBE, and the designated mediating variables. These results not only augment the academic literature by illustrating the psychological underpinnings bridging CSR to ESBE, but also equip the tourism and hospitality industry with actionable insights. Through informed CSR initiatives aligned with employee values, the sector can galvanize sustainable behaviors and create business models that resonate with the aspirations of the UN-SDGs, pointing the way to a more sustainable industry.

The effects of the COVID-19 pandemic period on stock market return and volatility. Evidence from the Pakistan Stock Exchange.

The COVID-19 pandemic has emerged as a significant event of the current century, introducing substantial transformations in economic and social activities worldwide. The primary objective of this study is to investigate the relationship between daily COVID-19 cases and Pakistan stock market (PSX) return volatility. To assess the relationship between daily COVID-19 cases and the PSX return volatility, we collected secondary data from the World Health Organization (WHO) and the PSX website, specifically focusing on the PSX 100 index, spanning from March 15, 2020, to March 31, 2021. We used the GARCH family models for measuring the volatility and the COVID-19 impact on the stock market performance. Our E-GARCH findings show that there is long-term persistence in the return volatility of the stock market of Pakistan in the period of the COVID-19 timeline because ARCH alpha (ω1) and GARCH beta (ω2) are significant. Moreover, is asymmetrical effect is found in the stock market of Pakistan during the COVID-19 period due to Gamma (ѱ) being significant for PSX. Our DCC-GARCH results show that the COVID-19 active cases have a long-term spillover impact on the Pakistan stock market. Therefore, the need of strong planning and alternative platform should be needed in the distress period to promote the stock market and investor should advised to make diversified international portfolio by investing in high and low volatility stock market to save their income. This study advocated the implications for investors to invest in low volatility stock especially during the period of pandemics to protect their return on investment. Moreover, policy makers and the regulators can make effective policies to maintain financial stability during pandemics that is very important for the country's economic development.

Syntheses, structural, photophysical and theoretical studies of heteroleptic cycloplatinated guanidinate(1-) complexes bearing acetylacetonate and picolinate ancillary ligands.

Cycloplatination of symmetrical N,N',N''-triarylguanidines, (ArNH)2C[double bond, length as m-dash]NAr with cis-[Pt(TFA)2(S(O)Me2)2] in toluene afforded cis-[Pt(TAG)(TFA)(S(O)Me2)] (TAG = triarylguanidinate(1-)-κC,κN; TFA = OC(O)CF3; 6-9) in 75-82% yields. The reactions of 6-9 and the previously known cis-[Pt(TAG)X(S(O)Me2)] (X = Cl (1) and TFA (2-5)) with acetylacetone (acacH) or 2-picolinic acid (picH) in the presence of a base afforded [Pt(TAG)(acac)] (acac = acetylacetonate-κ2O,O'; 10-18) and [Pt(TAG)(pic)] (pic = 2-picolinate-κN,κO; 19) in high yields. The new complexes were characterised by analytical, IR and multinuclear NMR spectroscopies. Further, molecular structures of 11, 12, 13·0.5 toluene and 14-19 were determined by single crystal X-ray diffraction. Absorption spectra of 10-19 in solution and their emission spectra in crystalline form were measured. Platinacycles 10-19 are bluish green light emitter in the crystalline form, and emit in the λPL = 488-529 nm range (11 and 13-19) while 12 emits at λPL = 570 nm. Unlike other platinacycles, the emission band of 12 is broad, red shifted, and this pattern is ascribed to the presence of an intermolecular N-H⋯Pt interaction involving the endocyclic amino unit of the six-membered [Pt(TAG)] ring and the Pt(ii) atom in the adjacent molecule in an asymmetric unit of the crystal lattice. Lifetime measurements were carried out for all platinacycles in crystalline form, which revealed lifetime in the order of nanoseconds. The origin of absorption and emission properties of 11, 15, 18 and 19 were studied by TD-DFT calculations.

Platelet-rich plasma intra-articular knee injections from open preparation techniques do not pose a higher risk of joint infection: A systematic review of 91 randomized controlled trials and 5914 injections.

Purpose: To compare the infection rate of intraarticular platelet-rich plasma (PRP) knee injections between open and closed techniques in randomized controlled trials (RCTs) published in the last decade. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed, Scopus and Virtual Health Library were accessed in October 2022 using the terms 'platelet-rich plasma', 'PRP', 'knee' and 'tibiofemoral' alone and in combination with Boolean operators AND/OR. RCTs published during the last 10 years evaluating PRP intra-articular knee injections were considered eligible. Studies were excluded if the kit/preparation technique was not described. Data were presented using individual studies' absolute values, totals, and pooled percentages. Publication bias was assessed using the ROBIS tool. Results: Ninety-one studies met the predetermined eligibility criteria. Forty-one implemented a closed technique, while 50 were open. All studies implementing a closed technique disclosed their commercial kits. Only 16 studies (17.58%) failed to report joint infections. Among the studies reporting joint infections as outcomes, 30 implemented a closed technique with 1195 patients, 1921 intra-articular knee injections and 95.44% of patient follow-up. On the other hand, 45 of them implemented an open technique with 2290 patients, 3993 intra-articular knee injections and 97.07% of patient follow-up. No patient had a joint infection among the included studies. Thirty-three studies prepared their PRP in controlled environments (36.26%). Most studies did not report where the preparation occurred (48.35%). Only twelve studies disclosed using laminar flow during preparation (13.19%). The infection rate for both techniques was 0 per 1000 knee injections. Conclusion: Open PRP preparation techniques do not pose a higher risk of joint infection and can lower manufacturing costs when appropriate facilities are available. However, PRP preparation setting and laminar flow implementation data are deficient, and minimal requirements for good manufacturing practices demand further studies while adhering to local and regional regulations. Level of Evidence: Level I, systematic review of RCTs.

Frequency of generalised anxiety disorder and associated factors in an urban settlement of Karachi.

OBJECTIVE: The study was undertaken to find the frequency of Generalised Anxiety Disorder (GAD) along with associated factors in an urban settlement of Karachi. METHOD: A cross-sectional study was conducted at Defence Housing Authority (DHA), a posh area of Karachi. The sample population consisted of residents of ages between 18 and 65. The sample of 420 was completed by randomly going to residences in the DHA area. Self-administered questionnaires were handed out after taking informed consent. General Anxiety Disorder (GAD) 7 scale was used to estimate the anxiety level. The data was entered and analysed using SPSS version 16.0. Pearson's chi-square was used as the primary statistical test. RESULTS: The mean anxiety score of the total individuals selected was 5.1 +/- 3.79. Males reported a mean score of 4.99 +/- 4.01 while females reported a mean score of 5.25 +/- 3.42. A score of 5 is considered as the threshold for anxiety and anything below 5 is considered as normal. Based on this benchmark, out of the total sample size of 420, 211 (50.2%) individuals reported some degree of anxiety. Employment and education status were found to be significantly associated (p = 0.01) with anxiety among the participants. CONCLUSION: Based on the results, the high prevalence of anxiety in one of the most developed areas of Karachi is alarming. For 50.2% of the respondents to have anxiety is high considering the sample chosen represented individuals that were educated and had a high standard of living. The major factors responsible for anxiety cited by respondents were chronic diseases and emotional harm.

Transethosomes: A Promising Challenge for Topical Delivery Short Title: Transethosomes for Topical Delivery.

Skin provides an excellent barrier to molecular transport, as the stratum corneum is the most formidable barrier to the passage of most pharmaceuticals. Various attempts have been made to improve drug administration into the body through intact skin. Though very few routes are as attractive as the topical route, drug transport through the skin is challenging. To overcome the challenges, researchers have found a system in which the drug is encapsulated into the vesicle, penetrating deeper into the skin to hit the target site. Vesicular systems like transethosome, an ultra- deformable vesicle (UDV), tend to accumulate in the skin layers. Since transethosomes have small particle size and can easily alter the shape of vesicles compared to other vesicular systems, they can penetrate through the layers of skin. Hence, the drug encapsulated into transethosomes can easily reach the target site. Transethosomes consist of ethanol and phospholipids along with an edge activator. Ethanol and edge activator help to enhance the skin permeation of transethosomes. Various methods of preparation of transethosomes, comparison of transethosomes with other lipid vesicles, characterization of transethosomes, and application of transethosomes have been covered in this review. Transethosomes can deliver a different variety of drugs, such as anticancer, corticosteroids, proteins and peptides, analgesics.

Cardiopulmonary Arrest During Pregnancy: A Review Article.

Massive pulmonary embolism (PE) is an uncommon but severe complication of pregnancy or during the first few weeks after giving birth. Our intention was to thoroughly analyze the information available to its management methods. Significant bleeding of mother survival and early deliveries in fetal survivals were having hemorrhage and were having key outcomes. We found 127 severe PE cases that have had at least one form of treatment (at least 83% big; 23% with cardiac arrest). The 83 women who received thrombolysis had a 94% (95%) survival rate. Cardiac arrest in pregnancy is uncommon, although maintaining current competency can be challenging. While maternal mortality rates have decreased globally over the past 25 years, they have increased in the United States. The intricacy of the maternal mortality issue is a result of a number of clinical and socioeconomic problems such as unequal healthcare access, racial and ethnic disparities, maternal comorbidities, and bias in epidemiologic ascertainment. The importance of doctors being prepared to react to a potential maternal cardiac arrest in any situation where they are providing treatment for pregnant women is highlighted by the rise in maternal mortality. For the treatment of maternal cardiac arrest, an interdisciplinary team with expertise in both the maternal resuscitation procedure and the physiological changes that take place during pregnancy is necessary. Additionally offered are basic and advanced cardiac life support protocols. Techniques to remove obstacles like aortocaval compression that could impair the effectiveness of resuscitation should be used.

Directional Amplified Photoluminescence through Large-Area Perovskite-Based Metasurfaces.

Perovskite nanocrystals are high-performance, solution-processed materials with a high photoluminescence quantum yield. Due to these exceptional properties, perovskites can serve as building blocks for metasurfaces and are of broad interest for photonic applications. Here, we use a simple grating configuration to direct and amplify the perovskite nanocrystals' original omnidirectional emission. Thus far, controlling these radiation properties was only possible over small areas and at a high expense, including the risks of material degradation. Using a soft lithographic printing process, we can now reliably structure perovskite nanocrystals from the organic solution into light-emitting metasurfaces with high contrast on a large area. We demonstrate the 13-fold amplified directional radiation with an angle-resolved Fourier spectroscopy, which is the highest observed amplification factor for the perovskite-based metasurfaces. Our self-assembly process allows for scalable fabrication of gratings with predefined periodicities and tunable optical properties. We further show the influence of solution concentration on structural geometry. By increasing the perovskite concentration 10-fold, we can produce waveguide structures with a grating coupler in one printing process. We analyze our approach with numerical modeling, considering the physiochemical properties to obtain the desired geometry. This strategy makes the tunable radiative properties of such perovskite-based metasurfaces usable for nonlinear light-emitting devices and directional light sources.

Development and optimization of transethosomal gel of apigenin for topical delivery: In-vitro, ex-vivo and cell line assessment.

The main aim of this study was to optimize the transethosomes of apigenin formulated by the thin film hydration method using surfactant Span 80. Response surface Box-Behnken design with three levels of three factors was used to design and optimize the formulations. The prepared transethosomal formulations were characterized for entrapment efficiency, vesicle size, and flux to obtain the optimized formulation batch. The optimized batch was further incorporated into the gel and characterized for the in-vitro, ex-vivo, and cytotoxic studies. The result showed the optimized transethosomes were smooth, nanosized, unilamellar, and spherical with an entrapment efficiency of 78.75 ± 3.14 %, a vesicle size of 108.75 ± 2.31 nm, and a flux of 4.10 ± 0.63 µg/cm2/h. In-vitro cumulative drug release of transethosomal gel of apigenin (TEL gel) and the conventional gel was 92.25 ± 3.5 % and 53.40 ± 3.10 %, respectively, after 24 h study. Ex-vivo permeation of TEL gel and conventional gel showed 86.20 ± 3.60 % and 51.20 ± 3.20 % permeation of apigenin at 24 h, respectively. A cytotoxic study confirmed that TEL gel significantly reduces cell viability compared to conventional gel. The results suggested that topical application of apigenin transethosomal gel may be a better treatment strategy for skin cancer because of the prolonged sustained release of the drug and the better permeability of apigenin through the skin.

Vitamin D status in very low birth weight infants and response to vitamin D intake during their NICU stays: a prospective cohort study.

OBJECTIVE: To evaluate vitamin D status in very low birth weight (VLBW) infants and response to vitamin D intake. STUDY DESIGN: In this prospective cohort study of VLBW infants, 25-hydroxyvitamin D [25(OH)D] was measured regularly starting at birth. Daily vitamin D intake was estimated from parenteral and enteral sources. RESULTS: Of the included 83 infants born between November 2016 and March 2018, 44 (53%) had 25(OH)D < 30 ng/mL at birth but achieved vitamin D sufficiency (VDS) by 3 weeks while receiving 120-400 IU/day. Twenty-three (27.7%) infants had at least one 25(OH)D level >100 ng/mL during the study period. Infants whose intake was > 600 IU/day had higher prevalence of vitamin D excess (VDE). CONCLUSION: In our study, low 25(OH)D was common in VLBW infants at birth. Vitamin D intake of 120-260 IU/day from parenteral and 200-400 IU/day from enteral route was appropriate for VLBW infants to achieve VDS. Doses > 600 IU/day increased risk of VDE.

Fetal Heart Tracing Patterns and the Outcomes of Newborns With Meconium-Stained Amniotic Fluid.

Objective To determine if the presence of meconium-stained amniotic fluid (MSAF) by itself or in combination with abnormal fetal heart tracing (FHT) (category II and III) is associated with poor neonatal outcomes in full-term newborns. Design/methods This is a retrospective cohort study. Cases included singleton and full-term neonates with MSAF. Cases were compared to matched controls (clear amniotic fluids) for the outcomes. SPSS (IBM SPSS Statistics for Windows, Version 22.0, Armonk, NY, USA) and SAS 9.4 (SAS Institute Inc., Cary, NC, USA) were used for data analysis. Results From 5512 deliveries, 210 cases (MSAF group) and 210 matched controls were identified. Cases and controls were similar in most maternal characteristics. Abnormal FHT was present in 43.2% of cases compared to 17.6% of controls (p<0.001). Low Apgar scores (<7) at one and five minutes were more common in the MSAF group (p=0.03 and 0.007, respectively). The neonatal intensive care unit (NICU) admission rate was also higher in the MSAF group (p=0.002). However, the mean hospital stay was similar in both groups (p=0.44). Twenty-two (10.5%) cases required resuscitation at birth compared to six (2.9%) controls (p=0.003). After applying the logistic regression model to adjust for the FHT pattern and Apgar scores at one minute, the association of MSAF with resuscitation lost significance. The factors associated with resuscitation requirement at birth were Apgar score at one minute (adjusted odds ratios (aOR) 4.1; 95% CI 2.8-5.1, p<0.001) and abnormal FHTs (aOR, 0.03; 95% CI 0.004-0.257, p=0.001). Conclusions Neonates born with MSAF were more likely to have abnormal FHT and require resuscitation at birth. However, after adjusting for confounding factors, abnormal FHT and one-minute Apgar scores were the only variables predictive of resuscitation needs at birth.

Skin Grafting, Cryopreservation, and Diseases: A Review Article.

Food supplements may be consumed through diet and have been shown to modify skin functions, making them helpful in the management of skin aging. However, there are not many clinical trials that back up these assertions. The stratum corneum, which acts as the organism's contact with its environment, is the principal function of the epidermis of land vertebrates. Antioxidants are chemicals that slow down or prevent other molecules from oxidizing. In people's diets, their use has considerably expanded in recent years. Due to their benefits for health, nutrition, and therapy, natural antioxidants are increasingly being used in place of synthetic antioxidant components. A popular component thought to be an antioxidant is hydrolyzed collagen. With aging comes a steady loss of physiological integrity, capacity to handle stress from the inside out, and function. This is a byproduct of several intricate biological processes that are affected by diseases both local and systemic as well as constitutive and environmental variables. Systemic and constitutive (genetic) variables influence skin aging and its phenotypic manifestation. The biological process of skin aging is complicated and impacted by both external and endogenous causes. The primary contributor to skin cancer is sun exposure. Ultraviolet radiation from the sun can kill skin cells by directly absorbing DNA damage. The skin's hydration is a crucial factor that affects its mechanical and physical characteristics. This study looks at how the stratum corneum's molecular and macroscopic characteristics interact and change with skin wetness. Although there is little information written about them and even less is understood about them, moisturizers are a crucial component of a dermatologist's toolkit. There is a plethora of anticipated skin products on the market, but their true scientific function is yet unknown. These items play a well-known part in many skin problems, while occasionally being dismissed as simple cosmetics.

Sleep quality and mental health in coronavirus disease 2019 patients and general population during the pandemic.

OBJECTIVE: Sleep problems during the coronavirus disease 2019 (COVID-19) pandemic commonly affected general populations. Data on the effect of the COVID-19 pandemic on sleep quality in Saudi Arabia are scarce. Thus, the aim of our study was to evaluate sleep quality and assess the psychological burden of the pandemic in COVID-19 patients and the general population. METHODS: This was a multicenter, observational, cross-sectional survey. Participants with COVID-19 were recruited from different health-care centers in the western region during the lockdown period from May 13, 2020 to September 2, 2020. All participants completed a validated online survey. The control group comprised individuals from the general public who responded to the online survey through social media. Demographic data, COVID-19 status, and history of chronic diseases were collected. Sleep quality, depression, and insomnia were assessed using validated questionnaires. RESULTS: In total, 1091 participants were surveyed and 643 (58.9%) were positive for COVID-19. Poor sleep quality was reported in 66.1% of COVID-19 patients (mean score ± standard deviation [SD] 6.9 ± 4.0) and 72.8% of controls (mean score ± SD 7.6 ± 4.3). Insomnia affected 50.5% of COVID-19 patients (mean score ± SD 6.5 ± 5.5) and 58.5% of controls (mean score ± SD 7.6 ± 5.5). Depression was diagnosed in 39.5% of COVID-19 patients (mean score ± SD 4.7 ± 4.6) and 70.1% of controls (mean score ± SD 8.9 ± 6.7). CONCLUSIONS: The COVID-19 pandemic had a great impact on mental health and sleep quality in both COVID-19 patients and the general population but more pronounced in the general population.

A Case of Infantile Perianal Pyramidal Protrusion Masquerading As Imperforate Anus at Birth.

Infantile perianal pyramidal protrusion (IPPP) is an uncommon and underreported benign cutaneous lesion characterized by a protrusion from the anal orifice. It is also believed to be often mistaken for other conditions. The unawareness of this lesion may be responsible for underreporting and an excessive concern both in providers and in parents. Timely diagnosis and reassurance need to be emphasized in the provider community. We report an interesting case of IPPP on the first day of life, which was erroneously diagnosed as imperforate anus at her delivery.

Impact of Substantive Staging and Communicative Staging of Sustainable Servicescape on Behavioral Intentions of Hotel Customers through Overall Perceived Image: A Case of Boutique Hotels.

Customers have become very sensitive regarding the innovative evaluation of services. Due to competition in the hospitality industry, it is a challenge for hotel marketers to understand customers' behavior. There is scant research in the hotel industry of Pakistan and especially on boutique hotels. This research seeks to measure the relationship between substantive, communicative elements of the sustainable servicescape and behavioral intentions (word of mouth) in a boutique hotel setting. However, the mediating effect of the overall perceived image is examined between these constructs. Responses of boutique hotel visitors were collected from Lahore, Islamabad, Faisalabad, and Murree. Data were analyzed by using structural equation modeling (SEM). Results display that both substantive and communicative servicescape elements positively affect the perceived image of customers, which has a positive influence on behavioral intentions such as word of mouth (WOM). Theoretical and practical implications are also discussed.

COVID-19 Repercussions: Office and Residential Emissions in Pakistan.

The purpose of this study is to find empirical evidence on whether work from home or residential emissions reduces office emissions. Based on existing research the study supports that there are short-term effects on office emissions, i.e., carbon emissions do not outshine the long-term effects. The shift from offices to working from home due to COVID-19 regulations meant more people operating from home as maintaining their position in the market was crucial. The potential research area is to understand how this would affect energy usage and carbon emissions. This study has used a before and after mixed approach to collect data from 301 working-from-home employees and 348 top managers who are responsible for monitoring the employees in a work from home setting. Convenience sampling helped collect responses in a timely manner as offices were not allowing visitors and collecting data in person was difficult, so online surveys were conducted. Work from home reduced usage of office equipment, transportation, pollution, etc. The air quality improved considerably but our findings show that the low emissions were only short-lived. This was not a long-term scenario as organizations kept practicing their operations even at home and the emissions stayed in the environment. Future suggestions and implications are also provided. The results give new insights to researchers in the field of sustainability and the environment.

Linear and nonlinear optical probing of various excitons in 2D inorganic-organic hybrid structures.

Nonlinear optical properties, such as two-(or multi-) photon absorption (2PA), are of special interest for technologically important applications in fast optical switching, in vivo imaging and so on. Highly intense infrared ultrashort pulses probe deep into samples and reveal several underlying structural perturbations (inter-layer distortions, intra-layer crumpling) and also provide information about new excited states and their relaxation. Naturally self-assembled inorganic-organic multiple quantum wells (IO-MQWs) show utility from room-temperature exciton emission features (binding energies ~200-250 meV). These Mott type excitons are highly sensitive to the self-assembly process, inorganic network distortions, thickness and inter-layer distortions of these soft two-dimensional (2D) and weak van der Waal layered hybrids. We demonstrate strong room-temperature nonlinear excitation intensity dependent two-photon absorption induced exciton photoluminescence (2PA-PL) from these IO-MQWs, excited by infrared femtosecond laser pulses. Strongly confined excitons show distinctly different one- and two-photon excited photoluminescence energies: from free-excitons (2.41 eV) coupled to the perfectly aligned MQWs and from energy down-shifted excitons (2.33 eV) that originate from the locally crumpled layered architecture. High intensity femtosecond induced PL from one-photon absorption (1PA-PL) suggests saturation of absorption and exciton-exciton annihilation, with typical reduction in PL radiative relaxation times from 270 ps to 190 ps upon increasing excitation intensities. From a wide range of IR excitation tuning, the origin of 2PA-PL excitation is suggested to arise from exciton dark states which extend below the bandgap. Observed two-photon absorption coefficients (ß ~75 cm/GW) and two-photon excitation cross-sections (η2σ2 ~ 110GM), further support the evidence for 2PA excitation origin. Both 1PA- and 2PA-PL spatial mappings over large areas of single crystal platelets demonstrate the co-existence of both free and deep-level crumpled excitons with some traces of defect-induced trap state emission. We conclude that the two-photon absorption induced PL is highly sensitive to the self-assembly process of few to many mono layers, the crystal packing and deep level defects. This study paves a way to tailor the nonlinear properties of many 2D material classes. Our results thus open new avenues for exploring fundamental phenomena and novel optoelectronic applications using layered inorganic-organic and other metal organic frameworks.