Photobiomodulation-induced choriocapillaris perfusion enhancement and outer retinal remodelling in intermediate age-related macular degeneration: a promising therapeutic approach with short-term results

Purpose: To evaluate the effects of photobiomodulation (PBM) on choriocapillaris (CC) perfusion and drusen volume in patients with intermediate age-related macular degeneration (AMD). Methods: In this retrospective pilot study, 30 patients receiving PBM therapy and 30 age-matched controls were analysed. Treatment consisted of 8 sessions over 4 weeks using the EYE-LIGHT® device. Best-corrected visual acuity (BCVA), low luminance visual acuity (LLVA), mean drusen volume (MDV), and CC flow deficit percentage (FD%) were evaluated at baseline and 2-month follow-up. Results: The PBM group showed significant improvements in BCVA (Δ +3.2 ± 1.4 letters, p = 0.042), reduction in drusen volume (Δ –0.003 ± 0.001 mm3, p = 0.028), and decrease in choriocapillaris FD% (Δ –3.1 ± 1.4%, p = 0.024), while no significant changes were observed in the control group. Changes in choriocapillaris FD% correlated with BCVA improvement (r = –0.54, p = 0.002) and drusen volume reduction (r = 0.35, p = 0.042). Conclusions: PBM therapy induces significant choriocapillaris remodelling in intermediate AMD, associated with functional improvement and drusen volume reduction. These findings suggest a potential therapeutic role of PBM in modulating choroidal perfusion in AMD

Comprehensive functional profiling of yeasts: gastrointestinal resistance, metabolic capacities, and psychobiotic potential

This study delved into the underexplored psychobiotic potential of yeasts, systematically evaluating their gastrointestinal resilience and metabolic versatility in response to diverse carbon, nitrogen, and phenolic substrates. Among ten yeast strains screened, Wickerhamomyces anomalus GY4, Lachancea fermentati 9Y, and Saccharomyces cerevisiae KFAY3 demonstrated the highest gastrointestinal resistance and were selected. These strains exhibited strong auto-aggregation and hydrophobicity properties, essential traits for gut colonization. Phenomic analyses unveiled distinct metabolic fingerprints, with each strain demonstrating unique carbon and nitrogen utilization profiles, indicative of specialized functional pathways. Notably, W. anomalus significantly outperformed others in the production of short-chain fatty acids and gamma-aminobutyric acid (GABA), key metabolites linked to gut-brain axis modulation. Additionally, all strains effectively metabolized phenolic compounds in a strawberry-based matrix, significantly enhancing the bioavailability of metabolites with potential neuroprotective properties. Collectively, these findings illuminate the promising role of yeast as psychobiotic agents, offering a compelling avenue for the development of yeast-based therapeutic interventions targeting gut-brain axis regulation and mental health

Valutazione di composti bioattivi derivanti da matrici naturali per applicazioni in condizioni fisiologiche e patologiche

Le matrici naturali sono storicamente riconosciute come importanti fonti di potenziali farmaci: il loro utilizzo è infatti documentato dalla medicina tradizionale, sottoforma di rimedi, pozioni e oli. Nonostante molti prodotti naturali bioattivi rimangano tutt’ora non identificati, il loro potenziale continua ad essere riconosciuto e a destare l’interesse dei ricercatori. L'uso delle matrici naturali nel drug discovery deve tener conto delle problematiche associate alla natura stessa delle matrici, quali la variabilità biologica, le difficoltà nella caratterizzazione dei prodotti naturali e le complessità legata alla valutazione della loro bioattività: tali sfide hanno rallentato lo sviluppo dell'industria farmaceutica correlata ai prodotti naturali. Tuttavia, i prodotti naturali derivanti da piante e animali continuano a entrare nelle sperimentazioni cliniche o a fornire dei leads, soprattutto come agenti anticancro e antimicrobici. L'eccezionale diversità strutturale offerta dalle matrici naturali, rispetto alla chimica combinatoria standard, ha rinnovato l'interesse nel riconsiderare i prodotti naturali nel drug discovery. In questo lavoro, sono state selezionate due diverse matrici naturali per la valutazione in vitro della loro potenziale bioattività su tre linee cellulari renali umane, le non-tumorali HK-2 e due le tumorali Caki-1 e RCC-Shaw: (i) le urine di dromedario, come matrice di origine animale e (ii) gli estratti di Ganoderma adspersum, come matrice naturale di origine fungina. L’urinoterapia con le urine di dromedario come rimedio contro varie malattie è una pratica etnomedica diffusa nei paesi tradizionalmente associati ai dromedari, e diversi studi hanno cercato di svelare il potenziale terapeutico di questo sottoprodotto. Tuttavia, questi studi spesso trascurano fattori importanti, come l'osmolarità delle urine o l'impatto della concentrazione e/o composizione del siero utilizzato nelle colture cellulari, che potrebbero influenzare profondamente i risultati dei test in vitro. La bioattività di un set di diciassette urine di dromedario, provenienti da animali di sesso ed età diversi, è stata esaminata sulle linee cellulari renali umane sopra menzionate. Prima dei test di bioattività, sono stati considerati l'eventuale influenza dell'osmolarità dei campioni e il contenuto del siero fetale bovino (FBS) aggiunto al mezzo di coltura cellulare. Inoltre, una caratterizzazione preliminare dei campioni di urina testati attraverso analisi metabolomica basata sulla Risonanza Magnetica Nucleare (NMR) ha evidenziato la presenza di diversi metaboliti tra campioni bioattivi e inattivi. D'altra parte, il Ganoderma adspersum è un tipo di fungo medicinale principalmente distribuito nelle regioni meridionali dell'Europa, recentemente riconosciuto per avere potenziali effetti bioattivi, tra cui effetti antiproliferativi contro le cellule cancerose. In questo studio, è stata indagata l'attività antiproliferativa degli estratti etanolici derivati dal Ganoderma adspersum. Sia gli estratti etanolici ottenuti dal mezzo di fermentazione che dal micelio sono stati testati in vitro e analizzati spettroscopicamente. Lo studio ha rivelato che l'estratto etanolico del micelio ha mostrato una significativa riduzione della vitalità delle cellule tumorali renali umane. Al contrario, non è stato osservato alcun impatto sulle cellule renali umane non tumorali, mentre l'estratto derivato dal mezzo fermentato non ha avuto un'influenza significativa sulla vitalità cellulare. L'analisi tramite Risonanza Magnetica Nucleare (NMR) ha rivelato notevoli cambiamenti nella composizione metabolica dell'estratto del mezzo fermentato (non attivo) rispetto a quella dell'estratto del micelio (attivo), suggerendo il ruolo di specifici metaboliti nell'attivazione dell'apoptosi osservata nelle cellule cancerose.Natural matrices have historically been important sources of potential drug leads, with their use documented in traditional medicines as remedies, potions, and oils. Despite many bioactive natural products remaining unidentified, their potential continues to be recognized. The use of natural matrices in drug discovery faces significant challenges, such as variability in starting materials, characterization difficulties, and scaling issues for high-throughput screening of bioactivity. These challenges have slowed the development of the natural product-related pharmaceutical industry. Nonetheless, natural products from plants and animals persist in entering clinical trials or providing leads, especially for anticancer and antimicrobial agents. The exceptional structural diversity offered by natural matrices, compared to standard combinatorial chemistry, has renewed interest in revisiting natural products for drug discovery. In this work, two different natural matrices were selected in order to assess their potential bioactivity on three human renal cell lines, the non-tumor HK-2, and the tumor Caki-1 and RCC-Shaw: (i) the animal-derived natural matrix of dromedary urines, and (ii) the Fungi-derived natural matrix of Ganoderma adspersum extracts. Indeed, dromedary urinotherapy as a remedy against various illnesses is a widespread ethnomedical practice, well recognized in traditional dromedary countries, and several studies tried to unravel the therapeutic potential of this animal by-product. However, these studies often overlooked important factors, such as the measurement of urine osmolarity or the impact of concentration and/or composition of the serum used in cell cultures, which could deeply influence the in vitro tests results. The bioactivity of a set of seventeen dromedary urines, derived from animals of different sex and age, on the above-mentioned human renal cell lines. The possible influence of the samples’ osmolarity and the content of the fetal bovine serum (FBS) added to the cell culture medium were considered prior to bioactivity testing. Moreover, a preliminary characterization of the tested urine samples through Nuclear Magnetic Resonance (NMR) – based metabolomics analysis pointed out the presence of different metabolites between bioactive and inactive samples. On the other hand, Ganoderma adspersum is a type of medicinal fungus mainly distributed in the southern regions of Europe recently reported to have potential bioactive effects, including antibacterial, anticholinesterase, and antioxidant activities. In addition, a few works reported about its antiproliferative effects against cancer cells. Here, the antiproliferative activity of ethanolic extracts derived from Ganoderma adspersum was investigated. Both the ethanolic extracts obtained from the media after fermentation and of the mycelium were tested in vitro and spectroscopically analyzed. The study revealed that the mycelium ethanolic extract exhibited a significant reduction in the viability of tumor human renal cells Caki-1 and RCC-Shaw, up to 90% for RCC-Shaw cells after 72 hours of exposure. Conversely, no impact on the non-tumor human renal HK-2 cells was observed. Interestingly, the extract derived from the fermented medium had no significant influence on cell viability. Nuclear Magnetic Resonance (NMR) analysis revealed remarkable changes in the metabolic composition of fermented medium extract (not active) compared to that of mycelium extract (active), suggesting the role of specific metabolites in the activation of apoptosis observed on the cancer cells

Analisi dell'editing A-to-I dell'RNA nella sclerosi laterale amiotrofica

L’editing dell’RNA da adenosina a inosina (A-to-I) rappresenta una modifica epitranscrittomica fondamentale nel modulare l’espressione genica nei trascrittomi umani. Studi precedenti hanno evidenziato come la disregolazione di questo processo sia associata a diverse malattie, tra cui patologie neurologiche e neurodegenerative come ischemia cerebrale, schizofrenia, epilessia, malattia di Alzheimer e cancro. Un possibile legame è stato ipotizzato anche tra editing aberrante dell’RNA e sclerosi laterale amiotrofica (SLA), sebbene il ruolo preciso di questa modifica nella SLA rimanga poco chiaro. Esaminare il coinvolgimento dell’editing dell’RNA nella SLA potrebbe offrire nuove prospettive sui meccanismi molecolari della malattia e su potenziali approcci terapeutici. La cosiddetta “ipotesi giapponese” propone che una riduzione dell’editing nel sito Q/R nell’mRNA di GRIA2, mediata dall’enzima ADAR2, contribuisca alla morte dei motoneuroni tramite l’eccitotossicità dei recettori AMPA. Questa riduzione è legata a una diminuzione dell’espressione di ADAR2. Le evidenze a supporto di questa ipotesi derivano da studi su motoneuroni microdissezionati da tessuti post-mortem di pazienti con SLA sporadica e da modelli murini condizionali privi di ADAR2. Tuttavia, per confermare e ampliare queste osservazioni, sono necessarie ulteriori indagini. A tale scopo, è stata condotta un’analisi approfondita dell’editing A-to-I dell’RNA su due grandi coorti di pazienti con SLA. La prima, la coorte TARGET ALS, include 1.373 dataset di sequenziamento dell’RNA ottenuti da tessuti del sistema nervoso centrale post-mortem di pazienti con SLA sporadica e controlli sani. La seconda, ANSWER ALS, comprende dati di RNA-seq derivati da motoneuroni generati da cellule staminali pluripotenti indotte (iPSC) di 249 donatori, inclusi pazienti con SLA e soggetti sani. I risultati ottenuti mostrano un’alterazione dell’attività di editing A-to-I nella SLA, principalmente associata alla neuroinfiammazione. Poiché non esistono modelli cellulari consolidati per studiare il ruolo dell’editing dell’RNA nella SLA, è stato sviluppato un modello innovativo di motoneuroni inducibili a partire da cellule staminali embrionali HUES 03 con ridotta espressione di ADAR2. Questo sistema sperimentale consente di analizzare specificamente la disfunzione dell’editing A-to-I nella SLA, validando ipotesi come quella giapponese e studiando il ruolo fisiologico di questa modifica nella neurodegenerazione. Nel contesto del mio dottorato, ho trascorso cinque mesi presso l’Università Medica di Vienna, sotto la supervisione del Professor Michael F. Jantsch, per indagare l’interazione tra le modifiche epitranscrittomiche. In particolare, mi sono concentrato sulla relazione tra metilazione m6A e editing A-to-I. Studi recenti suggeriscono che la m6A potrebbe facilitare l’editing A-to-I, favorendo il reclutamento o l’attività degli enzimi ADAR. Per approfondire questa ipotesi, ho sviluppato un sistema sperimentale basato sulla co-trasfezione di una guida RNA, un vettore λN-ADAR2 contenente il dominio deaminasi, e un vettore per l’espressione di Meg3. Questo modello ha permesso di valutare come l’editing A-to-I influenzi la metilazione m6A sullo stesso sito target. Nonostante il grande numero di campioni analizzati, ulteriori studi sono necessari per comprendere il ruolo funzionale dell’editing A-to-I nella SLA e la sua interazione con altre modifiche epitranscrittomiche. Tecnologie di sequenziamento a lettura lunga potrebbero rivelare nuovi dettagli di questo processo, migliorando la comprensione dei meccanismi di regolazione genica post-trascrizionale nelle malattie neurodegenerative.Adenosine-to-inosine (A-to-I) RNA editing is an essential epitranscriptomic modification that modulates gene expression in human transcriptomes (Picardi et al., 2015). Dysregulation of RNA editing has been associated with several diseases, including neurological and neurodegenerative disorders such as brain ischemia, schizophrenia, epilepsy, Alzheimer’s disease (AD), and cancer (Hosaka et al., 2021; Karagianni et al., 2022, 2024; Picardi et al., 2015). A potential link between aberrant RNA editing and amyotrophic lateral sclerosis (ALS) has also been proposed, but its precise role remains poorly understood. Understanding the involvement of RNA editing in ALS could uncover molecular mechanisms underlying the onset and progression of the disease, paving the way for novel diagnostic and therapeutic approaches. According to the "Japanese hypothesis", reduced editing at the Q/R site in GRIA2 mRNA mediated by ADAR2, coupled with decreased ADAR2 expression, should contribute to motor neuron death via AMPA receptor excitotoxicity in sporadic ALS (Yukio Kawahara*, 2004). Although supported by laser microdissected motor neurons from post-mortem tissues (Gregory et al., 2020; Yukio Kawahara*, 2004) and a conditional ADAR2 mouse model (Naito et al., 2023; Sasaki et al., 2014; Yamashita et al., 2013; Yamashita & Kwak, 2019), further evidence is required. To fill this gap, we conducted an extensive analysis of A-to-I RNA editing in two large ALS cohorts. First, we examined the TARGET ALS cohort (CHAPTER 1), comprising 1,373 RNA-sequencing datasets from post-mortem central nervous system tissues of individuals with sporadic ALS and controls. Second, we analyzed RNA-seq data from motor neurons derived from induced pluripotent stem cells (iPSCs) of 249 donors in the ANSWER ALS cohort (CHAPTER 2), including sporadic ALS patients and healthy controls. Notably, our findings indicate an alteration in the activity of RNA editing in ALS, mainly related to neuroinflammation. Since no cellular models are currently available to investigate the role of RNA editing in ALS, we developed an inducible motor neuron model using HUES 03 embryonic stem cells (hESCs) with downregulated ADAR2. Our cell model should allow the study of A-to-I editing dysfunction in ALS (CHAPTER 3) and provide a controlled system to validate the "Japanese hypothesis" and the physiological role of recoding RNA editing in neurodegeneration. During the PhD course, I spend five months at the Medical University of Vienna in Professor Michael F. Jantsch’s laboratory, where I studied the interplay between RNA modifications, focusing the attention on the relationship between m6A methylation and A-to-I RNA editing. Recent studies challenge the traditionally accepted antagonistic relationship between these two modifications (Xiang et al., 2018), suggesting instead that m6A might facilitate A-to-I editing by enhancing ADAR enzyme recruitment or activity. To explore this hypothesis (CHAPTER 4), I performed co-transfection experiments involving an RNA guide, a λN-ADAR2 deaminase domain (DD) fusion vector, and a Meg3 expression vector. This system allowed for site-specific A-to-I conversion and subsequent evaluation of how this editing influences m6A methylation at the targeted site. Although the high number of screened samples, our results suggest that further investigations are needed to assess the functional role of RNA editing in ALS and the relationship with other concurrent modifications. Long-read-based sequencing platforms could help in unveiling yet unknown aspects of RNA editing in ALS, enhancing our understanding of post-transcriptional gene regulation in neurodegenerative diseases

Dalle VHS alle chatbot AI: l’evoluzione mediata dalla tecnologia di pratiche sessuali atipiche

Il presente contributo prende spunto da quattro casi studiati dagli Autori. N.1: morte asfittica, per impiccamento accidentale di tipo completo durante pratica auto-erotica filmata da una telecamera con sistema VHS, di uno studente 17enne del Nord Italia negli anni Novanta, le cui inclinazioni all’esibizionismo ed al voyeurismo erano ignote. N.2: morte asfittica per strangolamento da auto-costrizione durante pratica auto-erotica online di una cam girl britannica, 21enne, su richiesta di un cliente voyeurista, che assisteva al decesso senza chiamare i soccorsi. N.3: decesso di un soggetto 56enne per gli esiti di un bondage total-body, praticatogli e filmato da una 29enne statunitense, creator digitale di OnlyFans, che contestualmente si masturbava previo lauto compenso da parte della vittima stessa. N.4: donna britannica, 45enne, coniugata con prole da un ventennio, che, all’acme di una convivenza sempre più frustrante, divorzia dal marito e sviluppa una forma di dipendenza da Leo, chatbot AI basata su ChatGPT, con cui instaura un rapporto connotato da appagamento erotico mai sperimentato, consapevolezza di non poter “mai tornare a frequentare un umano” ed esibizione di un anello pseudo-nuziale con l’incisione “Mrs. Leo.exe”. La casistica esemplifica come l’evoluzione di comportamenti siffatti chiami comunque in causa una tecnologia che può portare, nella migliore delle ipotesi, alla strumentalizzazione dell’altro, oppure, nella peggiore, alla sua eliminazione concreta

Giustizia Climatica

Il contributo, inserito nella rubrica "Le Parole dell'Educazione", definisce la giustizia climatica in relazione ai processi educativi ed evidenziando quanto essa sia uno dei temi emergenti e maggiormente cogenti di un discorso pedagogico attento ai temi dell'ambiente e della sostenibilità

mRNA expression, tumor heterogeneity, and response to therapy in patients with advanced renal cell carcinoma treated with immune-based combinations (ARON-1α)

Background: Renal Cell Carcinoma (RCC) represents a spectrum of tumors, characterized by heterogeneous growth patterns, histology and response to immune-based combinations. Objectives: The aim of the present retrospective analysis was to investigate the mRNA expression of 32 genes associated with RCC carcinogenesis and their potential involvement in patients treated with first-line immune-based combination therapies. Additionally, we examined the role of tumor heterogeneity by comparing mRNA expression levels between primary renal tumors and metastatic sites in a group of patients included in the ARON-1 study. Patients and methods: The study included patients with advanced RCC treated with first-line immune-based therapies. Total RNA was extracted from fixed paraffin-embedded tissue slices using the RNeasy FFPE Mini Kit. Quantitative RT-PCR was performed using the IQ5 Multicolor real-time PCR detection system. Coefficient of variations were calculated for each gene and compared between primary and metastatic samples. Results: 17 patients were included in this analysis; 9 of them had both primary and metastatic samples available. Three of the 4 patients showing the highest mRNA expression levels of the 32 analyzed genes reported complete remissions, while 2 of the 3 patients with the lowest expression levels were primary refractory to first-line therapy. As for tumor heterogeneity, VEGFA was the only gene significantly deregulated in the paired comparison. Conclusions: We showed differences in mRNA expression between primary and metastatic sites, and proposed a possible link to the response to first-line immune combination therapies. Additional research is required to clarify their potential as prognostic or predictive biomarkers

Old-Growth Forests and Bryophyte Communities in Italy and the Broader Mediterranean Region: A Literature Review

Beginning with general references to old-growth forests and the numerous benefits that they provide at multiple levels, this review mentions the main surveys conducted in Italy to identify and characterise Italian old-growth forests and offers an overview of the state of knowledge on bryophytes of these ecosystems in Sicily. Then, it focuses on the relationship between bryophyte diversity and old-growth traits (e.g., structural characteristics, long-term continuity), as well as the potential use of bryophytes as bioindicators of forest continuity and naturalness. In this regard, studies on bryophyte floras and communities in old-growth forests were examined in detail not only for Italy but also for the broader Mediterranean region, also taking into account evidence from investigations conducted in other bioclimatic zones. The analysis shows that old-growth forests often provide refuges for rare and noteworthy taxa and host highly diverse bryophyte communities. However, it appears that in Mediterranean forests, which have been less studied than temperate and boreal forests, the influence of certain factors that are known to be important in other contexts, such as deadwood, may be comparatively less relevant. Also, bryophyte species highly related to old-growth stands or with mature and ancient trees in the Mediterranean area are reported

Metabolic-associated enthesitis: a review on pathophysiology, clinical relevance, diagnostic challenges, and perspective on target treatments

Entheses are specialized tissues that connect ligaments and tendons to the bone surface and are frequently involved in seronegative spondyloarthritis. Enthesitis can also be detected in patients with metabolic disorders (MD), regardless of baseline autoimmune rheumatic disease, posing real diagnostic challenges. The present review discusses the pathophysiology of enthesitis and metabolic-associated enthesitis, the clinical relevance of metabolic disorders on enthesitis-related outcomes, diagnostic challenges for adequate differential diagnosis, and possible therapeutic strategies to improve clinical outcomes. PubMed/MEDLINE and the Cochrane Library were searched for original articles, systematic reviews, and meta-analyses. References were screened according to a hierarchical analysis of studies by title, abstract, and full text, collected, presented, and discussed. Metabolic-associated enthesitis is attributable to mechanical stress/overload due to weight excess typically observed in metabolic disorders (MD), such as overweight/obese comorbid patients, metabolic syndrome (MS), and type 2 diabetes (T2D). Interleukin 1β, 6, 17, 18, and 23 and tumor necrosis factor-α play a crucial role in initiating and maintaining entheseal inflammation. Chronic hyperglycemia and insulin resistance lead to a vicious circle as they stimulate, upon activated, specialized T cells to produce these specific cytokines, thus maintaining entheseal inflammation chronically. MD is associated with more severe clinical presentation, worse response to pharmacological treatments, and poor entheseal outcomes also in patients with existing seronegative spondyloarthritis. Non-immune-mediated metabolic-associated enthesitis poses a real diagnostic challenge, possibly underestimating cases and potential misdiagnoses. From a therapeutic viewpoint, glucose control improvement and weight loss are associated with relevant amelioration of entheseal-related outcomes. Pharmacological and non-pharmacological interventions aiming to reduce body weight, improve glucose control and insulin sensitivity, and attenuate inflammation are desirable to achieve the therapeutic target. Glucagon-like peptide 1 receptor agonists and sodium-glucose co-transporter type 2 inhibitors, in add-on to non-steroidal anti-inflammatory drugs and immunomodulators when necessary, may have a therapeutic rationale in patients with metabolic-associated enthesitis. Awareness of metabolic-associated enthesitis is essential to improve the accuracy of differential diagnosis in patients with MD and prescribe appropriate therapeutic strategies. However, basic and clinical research is needed to understand the role of “antihyperglycemic” agents in better managing metabolic-associated enthesitis

The sonification of crystals: An explorative study on the its effect on learning|SONIFICARE I CRISTALLI: UNO STUDIO ESPLORATIVO SUGLI EFFETTI SULL’APPRENDIMENTO

In the last decades, several studies have applied sonification to teaching and learning within the STEAM disciplines (Science, Technology, Engineering, Art, Mathematics). This exploratory study aims to investigate the role of sonification in learning complex scientific concepts related to crystals. A sample of 36 participants was asked to study the molecular structures of Calcite, Ice, and Rock Salt. The sample was divided into three groups, each exposed to a different learning modality: «Reading + Video» vs «Reading + Audio-Video» vs «Reading + Audio». Participants were assessed in terms of overall learning and specific learning of each crystal. In addition, they were asked to evaluate the learning process for each crystal as well as the overall experience in terms of enjoyment, interest, ease, usefulness, and motivation. The results show that the «Reading + Audio» study modalities led to greater overall learning compared to the other two modes («Reading + Video» and «Reading + Audio-Video»). This was also observed for the specific learning of Ice and Rock Salt. No significant differences emerged regarding in terms of learning across the different study modalities. Finally, higher levels of learning were associated with i) a greater perception of ease and ii) a higher rating in terms of interest and motivation only in the audio-video study modalities. These findings provide preliminary evidence supporting the potential use of sonification as an effective tool for studying crystals