Improving interface quality for 1-cm2 all-perovskite tandem solar cells.

All-perovskite tandem solar cells provide high power conversion efficiency at a low cost1-4. Rapid efficiency improvement in small-area (<0.1 cm2) tandem solar cells has been primarily driven by advances in low-bandgap (approximately 1.25 eV) perovskite bottom subcells5-7. However, unsolved issues remain for wide-bandgap (> 1.75 eV) perovskite top subcells8, which at present have large voltage and fill factor losses, particularly for large-area (>1 cm2) tandem solar cells. Here we develop a self-assembled monolayer of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid as a hole-selective layer for wide-bandgap perovskite solar cells, which facilitates subsequent growth of high-quality wide-bandgap perovskite over a large area with suppressed interfacial non-radiative recombination, enabling efficient hole extraction. By integrating (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid in devices, we demonstrate a high open-circuit voltage (VOC) of 1.31 V in a 1.77-eV perovskite solar cell, corresponding to a very low VOC deficit of 0.46 V (with respect to the bandgap). With these wide-bandgap perovskite subcells, we report 27.0% (26.4% certified stabilized) monolithic all-perovskite tandem solar cells with an aperture area of 1.044 cm2. The certified tandem cell shows an outstanding combination of a high VOC of 2.12 V and a fill factor of 82.6%. Our demonstration of the large-area tandem solar cells with high certified efficiency is a key step towards scaling up all-perovskite tandem photovoltaic technology.

Transcriptomics and Spatial Proteomics for Discovery and Validation of Missing Proteins in the Human Ovary.

Efforts to understand the complexities of human biology encompass multidimensional aspects, with proteins emerging as crucial components. However, studying the human ovary introduces unique challenges due to its complex dynamics and changes over a lifetime, varied cellular composition, and limited sample access. Here, four new RNA-seq samples of ovarian cortex spanning ages of 7 to 32 were sequenced and added to the existing data in the Human Protein Atlas (HPA) database www.proteinatlas.org, opening the doors to unique possibilities for exploration of oocyte-specific proteins. Based on transcriptomics analysis of the four new tissue samples representing both prepubertal girls and women of fertile age, we selected 20 protein candidates that lacked previous evidence at the protein level, so-called "missing proteins" (MPs). The proteins were validated using high-resolution antibody-based profiling and single-cell transcriptomics. Fourteen proteins exhibited consistent single-cell expression patterns in oocytes and granulosa cells, confirming their presence in the ovary and suggesting that these proteins play important roles in ovarian function, thus proposing that these 14 proteins should no longer be classified as MPs. This research significantly advances the understanding of MPs, unearthing fresh avenues for prospective exploration. By integrating innovative methodologies and leveraging the wealth of data in the HPA database, these insights contribute to refining our understanding of protein roles within the human ovary and opening the doors for further investigations into missing proteins and human reproduction.

DL-Serine Hydrazide Hydrochloride Multiple-site Synergy Induced Effective and Stable Formamidine-Rich Perovskite Solar Cells.

The efficiency and stability of solar cells are two key indicators that determine for the commercial feasibility of photovoltaic devices. Formamidine-cesium perovskite has been extensively investigated since its excellent thermal stability and has great potential in achieving high power conversion efficiency. However, during the aging process, especially under light conditions, formamidine-rich perovskites are prone to produce iodine, and the escape of iodine is one of the important factors leading to device degradation. Here, DL-Serine Hydrazide Hydrochloride containing the reducing group is introduced into the precursor solution of formamidine-cesium perovskite, which achieves multiple-site passivation. Hydrazine reacts with iodine to reduce it to iodine ions, inhibiting the escape of iodine. In addition, carbonyl groups and uncoordinated lead ions form coordination bonds to reduce defects. In the end, the perovskite solar cell with DL-Serine Hydrazide Hydrochloride added achieves a champion efficiency of 22.22%, and maintains 85.88% of the initial efficiency after continuous exposure under 1 sun for 7000 s at a relative humidity of ≈40%. Additionally, DL-Serine Hydrazide Hydrochloride added device shows good stability in air environments with relative humidity of 50%-60%. DL-Serine Hydrazide Hydrochloride improves the stability of formamidine-rich perovskite solar cells and provides a low-cost strategy for commercial development.

Space-Confined Growth for Thickness-Controlled Cs3Bi2I9 Perovskite Single Crystal Wafers for X-Ray Detectors.

The Cs3Bi2I9 single crystal, as an all-inorganic non-lead perovskite, offers advantages such as stability and environmental friendliness. Its superior photoelectric properties, attributed to the absence of grain boundary influence, make it an outstanding X-ray detection material compared to polycrystals. In addition to material properties, X-ray detector performance is affected by the thickness of the absorption layer. Addressing this, a space-confined method is proposed. The temperature field is determined through finite element simulation, effectively guiding the design of the space-confined method. Through this innovative method, a series of thickness-controlled perovskite single crystal wafers (PSCWs) are successfully prepared. Corresponding X-ray detectors are then prepared, and the impact of single crystal thickness on device performance is investigated. With an increase in single crystal thickness, a rise followed by a decline in device sensitivity is observed, reaching an optimal value at 0.7 mm thickness at 40V mm-1 with a device performance of 11313.6µC Gy-1 cm-2. This space-confined method enables the direct growth of high-quality perovskite single crystals with specified thickness, eliminating the need for slicing or etching.

Sr(NH2SO3)(NO3)·H2O: An Ultraviolet Nonlinear Optical Material Exhibiting Strong Second-Harmonic Generation Response and Sufficient Birefringence.

Second-harmonic generation (SHG) response and birefringence stand as fundamental optical properties for nonlinear optical (NLO) materials. Up to now, engineering a strong SHG response and substantial birefringence in the sulfamate system has proven to be exceedingly challenging. A novel noncentrosymmetric compound, Sr(NH2SO3)(NO3)·H2O, has been meticulously designed by introducing the (NO3)- group characterized by significant polarizability anisotropy and hyperpolarizability into the polar non-π-conjugated (NH2SO3)- system. This compound exhibits a robust SHG response (5.2 × KDP), ample birefringence (0.077 at 546.1 nm), and a short ultraviolet (UV) absorption edge (290 nm). The linear and nonlinear optical properties can be attributed to the (NO3)- group and the (NH2SO3)- group. This study presents an effective approach that contributes to the design of more composite anionic UV NLO materials with excellent and balanced optical properties.

Cs2Mg(H2C3N3S3)4·8H2O: An Excellent Birefringent Material with Giant Optical Anisotropy in π-Conjugated Trithiocyanurate.

The design of giant birefringence was performed by adjusting cations to make parallel and compact alignments of π-conjugated (HxC3N3S3)x-3, where x = 1 and 2) groups with large polarizability anisotropy. Finally, the first mixed alkali/alkali-earth-metal trithiocyanurates, A2B(H2C3N3S3)4·nH2O (A = K, Rb, Cs; B = Mg, Sr; n = 5-8, 12), were designed and synthesized successfully. Importantly, Cs2Mg(H2C3N3S3)4·8H2O (III) and K2Sr(H2C3N3S3)4·5H2O (IV) possess large birefringences of 0.580 and 0.194 at 800 nm, respectively, of III has the largest birefringence among all practical birefringent crystals, cyanurates, and hydroisocyanurates.

Two Tellurium(IV)-Based Sulfates Exhibiting Strong Second Harmonic Generation and Moderate Birefringence as Promising Ultraviolet Nonlinear Optical Materials.

Two tellurium(IV)-based sulfate nonlinear optical (NLO) materials, Te2O3(SO4) and Te(OH)3(SO4)·H3O, were successfully synthesized via the mild hydrothermal method. Te2O3SO4 has a two-dimensional (2D) structure consisting of [Te6O12]∞ layers as well as [SO4] groups. Te(OH)3(SO4)·H3O features a simple 0D structure made up of an isolated [TeO3] pyramid and a [SO4] tetrahedra. Both of them are phase-matching materials and show remarkable powder second harmonic generation (SHG) efficiencies about 6 and 3 times that of KH2PO4 (KDP), respectively, for Te2O3SO4 and Te(OH)3(SO4)·H3O. Especially for Te(OH)3(SO4)·H3O, in addition to a large SHG response, it possesses a short UV cutoff edge (∼233 nm) as well as moderate birefringence (0.052@546.1 nm). Furthermore, theoretical calculations confirmed that their strong SHG effects are due to the synergistic effect of the [TeO3] pyramid and [SO4] tetrahedra.

Discovery of potent and selective Cdc25 phosphatase inhibitors via rapid assembly and in situ screening of Quinonoid-focused libraries.

Cell division cycle 25 (Cdc25) phosphatase is an attractive target for drug discovery. The rapid assembly and in situ screening of focused combinatorial fragment libraries using efficient modular reactions is a highly robust strategy for discovering bioactive molecules. In this study, we have utilized miniaturized synthesis to generate several quinonoid-focused libraries, by standard CuAAC reaction and HBTU-based amide coupling chemistry. Then the enzyme inhibition screening afforded some potent and selective Cdc25s inhibitors. Compound M5N36 (Cdc25A: IC50 = 0.15 ± 0.05 µM; Cdc25B: IC50 = 0.19 ± 0.06 µM; Cdc25C: IC50 = 0.06 ± 0.04 µM) exhibited higher inhibitory activity than the initial lead NSC663284 (Cdc25A: IC50 = 0.27 ± 0.02 µM; Cdc25B: IC50 = 0.42 ± 0.01 µM; Cdc25C: IC50 = 0.23 ± 0.01 µM). Moreover, M5N36 displayed about three-fold more potent against Cdc25C than Cdc25A and B, indicating that M5N36 could act as a relatively selective Cdc25C inhibitor. Cell viability evaluation, western blotting and molecular simulations provided a mechanistic understanding of the activity of M5N36. It showed promising anti-growth activity against the MDA-MB-231 cell line and desirable predicted physicochemical properties. Overall, M5N36 was proven to be a promising novel Cdc25C inhibitor.

M(NH2 SO3 )2 (M=Sr, Ba): Two Deep-Ultraviolet Transparent Sulfamates Exhibiting Strong Second Harmonic Generation Responses and Moderate Birefringence.

Over the last few decades, the development of each new nonlinear optical (NLO)-active functional unit has led to the discoveries of a series of excellent NLO materials. In the present work, based on first-principles studies, we identified a novel deep-UV (DUV) NLO-active functional unit, a non-π-conjugated group viz. (NH2 SO3 )- . By combining alkaline-earth metals with (NH2 SO3 )- group, two DUV transparent NLO sulfamates, M(NH2 SO3 )2 (M=Sr, Ba) with superior optical properties including strong SHG responses (1.2 and 2.7 × KH2 PO4 (KDP)), short UV cut-off edge (<190 nm) and moderate birefringence (0.056@589.3 nm for Sr(NH2 SO3 )2 ) were successfully synthesized. Our work has provided not only two promising DUV transparent NLO crystals, but also an innovative non-π-conjugated unit for developing more DUV transparent NLO materials.

A(H3C3N3O3)(NO3) (A = K, Rb): Alkali-Metal Nitrate Isocyanurates with Strong Optical Anisotropy.

The first alkali-metal nitrate isocyanurates, A(H3C3N3O3)(NO3) (A = K, Rb), were synthesized by the tactic of introducing (NO3)- into isocyanurate with a mild hydrothermal technique. They crystallized into the same monoclinic centrosymmetric (CS) space group P21/c, which featured a 2D [(H3C3N3O3)(NO3)]∞ layered structure separated by K+ and Rb+ cations, respectively. Both compounds exhibited short ultraviolet cutoff edges (λcutoff = 228 and 229 nm) and large birefringences (Δn = 0.253 and 0.224 at 546.1 nm). More importantly, in comparison with most of the isocyanurates and nitrates, they have better thermal stability with decomposition temperatures up to 319.8 and 324.4 °C. In addition, our theoretical calculations reveal that the π-conjugated groups play significant roles in improving the optical anisotropy. Remarkably, introducing a π-conjugated inorganic acid radical (NO3)- into isocyanurate is an extremely meaningful strategy to explore new UV birefringent crystals.

Ovarian Follicle Depletion Induced by Chemotherapy and the Investigational Stages of Potential Fertility-Protective Treatments-A Review.

Ovarian follicle pool depletion, infertility, and premature menopause are all known sequelae of cancer treatment that negatively impact the quality of life of young cancer survivors. The mechanisms involved in this undesired iatrogenic ovarian damage have been intensively studied, but many of them remain unclear. Several chemotherapeutic drugs have been shown to induce direct and indirect DNA-damage and/or cellular stress, which are often followed by apoptosis and/or autophagy. Damage to the ovarian micro-vessel network induced by chemotherapeutic agents also seems to contribute to ovarian dysfunction. Another proposed mechanism behind ovarian follicle pool depletion is the overactivation of primordial follicles from the quiescent pool; however, current experimental data are inconsistent regarding these effects. There is great interest in characterizing the mechanisms involved in ovarian damage because this might lead to the identification of potentially protective substances as possible future therapeutics. Research in this field is still at an experimental stage, and further investigations are needed to develop effective and individualized treatments for clinical application. This review provides an overview of the current knowledge and the proposed hypothesis behind chemotherapy-induced ovarian damage, as well as current knowledge on possible co-treatments that might protect the ovary and the follicles from such damages.

Ovarian Follicles Rescued 3 Days after Cyclophosphamide Treatment in Adolescent Mice: An Experimental Study Aiming at Maximizing Methods for Fertility Preservation through In Vitro Follicle Culture.

There is currently a lack of knowledge about the feasibility of performing procedures for fertility preservation after chemotherapy treatment has been initiated. In this experimental controlled study using adolescent mice, we aimed to investigate if the chance of rescuing and growing in vitro secondary follicles (SeF) would be affected three days after a single injection of cyclophosphamide (CPA). The main outcomes included were: 1) The number of SeF with good morphologic quality obtained per ovary 3 days after CPA injection, 2) SeF development in culture, 3) small follicle density (SFD) on histology, and 4) apoptosis markers, including terminal deoxynucleotidyl transferase dUTP nick end-labelling (TUNEL), mRNA expression, and distribution of p 53 upregulated modulator of apoptosis (Puma) and phosphatase and tensin homolog (Pten). We found a 60% reduction of SeF obtained per ovary in all CPA-treated groups vs. controls. However, in vitro survival rates at culture day 12 and antrum formation were similar among all groups. On histology, SFD was only significantly reduced in the high CPA dose group. Apoptotic cells were mainly found in large growing follicles of CPA groups. Our study indicates the feasibility of SeF isolation and in vitro follicle culture 3 days following CPA treatment and a still preserved SFD, particularly following a low-dose CPA treatment.

The Validity of Using Human Squamous Cell Carcinoma Associated Antigen and Cytokeratin 19 Fragment Antigen 21-1 to Predict Postoperative Adjuvant Radiotherapy for Nonbulky Early-Stage Squamous Cell Carcinoma of the Cervix.

OBJECTIVE: There are no generally accepted biomarkers for the optimal selection of radiotherapy-based or surgical-based treatment options for nonbulky early-stage squamous cell carcinoma of the cervix (IA1-IB1 and IIA1). The objective of this study was to assess the value of human squamous cell carcinoma-associated antigen (SCC-Ag) and cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) in evaluation of patients with nonbulky early-stage squamous cell carcinoma of the cervix to determine if radiotherapy is warranted after radical surgery. METHODS: Patients with stage IA1-IB1 and IIA1 squamous cell carcinoma of the cervix who were treated at the Department of Gynecological Oncology, Affiliated Tumor Hospital of Guangxi Medical University, from March 2012 to August 2014 (n = 308) were treated with radical hysterectomy and pelvic lymphadenectomy. The levels of SCC-Ag and CYFRA21-1 were detected by enzyme-linked immunosorbent assay before surgery. The relationship between the concentrations of SCC-Ag and CYFRA21-1 and risk factors was estimated through logistic regression and analysis of variance t test. The cutoff values of these 2 markers to evaluate the need for postoperative radiotherapy were identified and validated by receiver operating characteristic curve and κ consistency test, respectively. RESULTS: Serum SCC-Ag and CYFRA21-1 levels are significantly increased in patients who require postoperative radiotherapy with a risk factor score of at least 2 (n = 162). Logistic regression analysis revealed that deep stromal invasion and lymph node metastasis are independent risk factors for serum SCC-Ag value, and deep stromal invasion is an independent risk factor for the serum CYFRA21-1 value. Receiver operating characteristic curve revealed that the best predictive cutoff points of SCC-Ag and CYFRA21-1 values were 1.425 and 3.210 ng/mL, respectively. These results were validated by the κ consistency test applied to a validation group of patients. The results suggest that most patients with SCC-Ag and CYFRA21-1 values of at least 1.425 and 3.210 ng/mL, respectively, require postoperative radiotherapy. CONCLUSIONS: Detection of the levels of SCC-Ag and CYFRA21-1 may help guide an individual primary treatment plan for patients with nonbulky early-stage squamous cell carcinoma of the cervix.

The Upregulation of TRAF1 Induced by Helicobacter pylori Plays an Antiapoptotic Effect on the Infected Cells.

BACKGROUND: Tumor necrosis factor receptor-associated factor 1 (TRAF1) is a member of the TRAF family and is dysregulated in diseases, such as atheroma, lymphoma, and solid tumors, but the role of TRAF1 in gastric cancer remains unknown. This study was aimed to investigate the role of TRAF1 in Helicobacter pylori (H. pylori)-related cell apoptosis and gastric carcinogenesis. MATERIALS AND METHODS: The mRNA and protein expression levels of TRAF1 were measured in a panel of gastric cancer cell lines and in H. pylori -infected mice by quantitative real-time PCR (qPCR) and Western blotting. The transcription factor that mainly affects transcription of TRAF1 during H. pylori infection was identified. The roles of H. pylori virulence factors that regulate TRAF1 expression were analyzed using isogenic cagA-, vacA-, and cagE-null mutants. The effects of TRAF1 on gastric cell viability and apoptosis during H. pylori infection were detected using the standard MTS (cell viability) assay and flow cytometry, respectively. RESULTS: H. pylori infection induced TRAF1 overexpression in both gastric epithelial cells and mice. The expression of TRAF1 in response to H. pylori infection was majorly regulated by the activation of NF-κB and was strongly related to H. pylori virulence factor CagA. The upregulation of TRAF1 inhibited cell apoptosis and increased the viability of infected cells. CONCLUSIONS: H. pylori infection induces the overexpression of TRAF1 in gastric epithelial cells. The upregulation of TRAF1 plays an antiapoptotic role in H. pylori -infected gastric cells and may contribute to the gastric carcinogenesis.

Sensitive and selective turn-on fluorescence method for cetyltrimethylammonium bromide determination based on acridine orange-polystyrene sulfonate complex.

This work proposed a rapid and novel fluorescence-sensing system using a complex of acridine orange (AO) and polystyrene sulfonate (PSS) to sensitively recognize and monitor cetyltrimethylammonium bromide (CTAB) in an aqueous medium. AO can interact with PSS and a complex is formed via electrostatic attraction and hydrophobic interaction. The fluorescence of AO is greatly quenched after the introduction of PSS. Upon its subsequent addition, CTAB can interact and form a complex with PSS because the electrostatic attraction between CTAB and PSS is much stronger than that between AO and PSS, which results in significant fluorescence recovery. Interestingly, the proposed method can be applied for the discrimination and detection of surfactants with different hydrocarbon chain lengths due to their different binding affinity toward PSS. The detection limit for CTAB is as low as 0.2 µg/mL and the linear range is from 0.5 to 3.5 µg/mL. Moreover, we applied the sensor to the successful detection of CTAB in water samples. Copyright © 2015 John Wiley & Sons, Ltd.

Identification of Cultured and Natural Astragalus Root Based on Monosaccharide Mapping.

As the main substances responsible for immunomodulatory activity, saccharides can be used as quality indicators for Astragalus root (RA). Saccharide content is commonly determined by ultraviolet spectroscopy, which lacks species specificity and has not been applied in the Chinese Pharmacopoeia. Monosaccharide mapping based on trifluoroacetic acid (TFA) hydrolysis can be used for quantitative analysis of saccharide compositions. In addition, species specificity can be evaluated by analysis of the mapping characteristics. In this study, monosaccharide mapping of soluble saccharides in the cytoplasm and polysaccharides in the cell wall of 24 batches of RA samples with different growth patterns were obtained based on TFA hydrolysis followed by gas chromatography-mass spectrometry. Results indicated that the mapping and the molar ratios of saccharide compositions of the cultured and natural RA samples were different for both cytoplasm and cell wall. For example, the molar ratio of mannose and arabinose was more than 3.5:1 in cytoplasm in cultured RA, whereas the ratio was less than 3.5:1 in natural RA. This research not only lays a foundation for screening indicators for RA, but also provided new ways of evaluating the quality of Chinese medicinal materials in which saccharides are the main bioactive substances.

Production and cell surface display of recombinant anthrax protective antigen on the surface layer of attenuated Bacillus anthracis.

To investigate the surface display of the anthrax protective antigen (PA) on attenuated Bacillus anthracis, a recombinant B. anthracis strain, named AP429 was constructed by integrating into the chromosome a translational fusion harboring the DNA fragments encoding the cell wall-targeting domain of the S-layer protein EA1 and the anthrax PA. Crerecombinase action at the loxP sites excised the antibiotic marker. Western blot analysis, fluorescence-activated cell sorting and immunofluorescence analysis confirmed that PA was successfully expressed on the S-layer of the recombinant antibiotic marker-free strain. Notwithstanding extensive proteolytic degradation of the hybrid protein SLHs-PA, quantitative ELISA revealed that approximately 8.1 × 10(6) molecules of SLHs-PA were gained from each Bacillus cell. Moreover, electron microscopy assay indicated that the typical S-layer structures could be clearly observed from the recombinant strain micrographs.

[Isolation, purification and identification of polysaccharides from Gynura divaricata].

The purpose of this study was to isolate and purify polysaccharide from Gynura divaricata and analyze its monosaccharide composition. A water-soluble crude polysaccharide was obtained by hot water extraction, ethanol precipitation and deproteinization after degreasing. The crude polysaccharide then purified with DEAE-Sepharose Fast Flow column chromatography and dialysis. The monosaccharide composition and structure were analyzed by HPLC, UV spectrophotometer and 1H-NMR. The results showed that the purity and molecular weight of GDPS-2 and GDPS-3 were 87.3%, 2.03 x 10(4) Da and 90.9%, 4.29 x 10(4) Da, respectively. The UV spectrophotometer and 1H-NMR data suggested that glycosidic bond of GDPS-2 and GDPS-3 were a type. Both GDPs-2 and GDPs-3 were homogeneous polysaccharides, and GDPs-2 was mainly composed of glucuronic acid and xylose at a molar ratio of 1.1:0.63. GDPs-3 was mainly composed of rhamnose, glucuronic acid, galactose, xylose and galacturonic acid at a molar ratio of 0.32:6.0:0.21:1.75:4.3.

Multiwavelength erbium-doped fiber laser based on graphene oxide.

A multiwavelength erbium-doped fiber (EDF) laser based on graphene oxide (GO) has been proposed, to the best of our knowledge, for the first time, to generate an output of stable wavelengths. The structure mainly comprises a few layers of GO between two single-mode fibers incorporated into a capillary device and a Lyot comb filter. GO can show a good nonlinear optical effect, which is beneficial to suppress the mode competition caused by the EDF and stabilize the multiwavelength output. With assistance from the GO device, 11 stable simultaneous lasing signals with a power nonuniformity of about 1.5 dB are obtained. Wavelength spacing is about 0.42 nm and the linewidth of each wavelength is less than 0.07 nm.

The effect of co-regulation on English public speaking self-efficacy in collaborative oral presentations.

This study investigated the influence of co-regulation on public speaking self-efficacy in the context of collaborative oral presentations. A total of 237 students enrolled in an English course at a university in China took part in the research. The factor analysis findings revealed that learners' co-regulation in public speaking encompass five components: co-planning, co-monitoring, co-evaluation, effort regulation, and help-seeking. Public speaking self-efficacy, on the other hand, pertains to learners' confidence in aspects including the topic, language use, organization, and delivery during public speaking engagements. The path analysis demonstrated that co-planning was a significant predictor of students' self-efficacy in terms of the topic and organization. Moreover, the co-monitoring strategy exhibited direct and positive correlations with language and topic self-efficacy. Similarly, the co-evaluation strategy showed direct and positive relationships with language, delivery, and organization self-efficacy. Furthermore, both effort regulation and help-seeking strategies were found to have direct and positive impacts on organization self-efficacy. This study offers valuable implications for educators, trainers, and individuals aiming to enhance their public speaking self-efficacy in collaborative environments.