Complex Modifications Research Articles

Spectra without stories: reporting 94% dark and unidentified ancient proteomes.

Data-dependent, bottom-up proteomics is widely used for identifying proteins and peptides. However, one key challenge is that 70% of fragment ion spectra consistently fail to be assigned by conventional database searching. This 'dark matter' of bottom-up proteomics seems to affect fields where non-model organisms, low-abundance proteins, non-tryptic peptides, and complex modifications may be present. While palaeoproteomics may appear as a niche field, understanding and reporting unidentified ancient spectra require collaborative innovation in bioinformatics strategies. This may advance the analysis of complex datasets. 14.97 million high-impact ancient spectra published in Nature and Science portfolios were mined from public repositories. Identification rates, defined as the proportion of assigned fragment ion spectra, were collected as part of deposited database search outputs or parsed using open-source python packages. We report that typically 94% of the published ancient spectra remain unidentified. This phenomenon may be caused by multiple factors, notably the limitations of database searching and the selection of user-defined reference data with advanced modification patterns. These 'spectra without stories' highlight the need for widespread data sharing to facilitate methodological development and minimise the loss of often irreplaceable ancient materials. Testing and validating alternative search strategies, such as open searching and de novo sequencing, may also improve overall identification rates. Hence, lessons learnt in palaeoproteomics may benefit other fields grappling with challenging data.

Effect of microwave-assisted treatment on proximate, techno-functional, thermal, structural, and storage properties of TGN (Cyperus esculentus L.) flour.

The use of the emerging technique of microwave-assisted roasting on TGN (TGN) flour was investigated. Tiger nuts were subjected to microwave irradiation at 450, 600, and 900 W each at 5, 10, and 15 min, and milled to flour. The flours were analyzed for proximate, bioactive, techno-functional, morphological, thermal, and storage effects on their composition. An untreated sample was the control. The results revealed that microwave treatment significantly (P < 0.05) elicited various modifications in the proximate composition and techno-functional properties. The treatment improved the bioactive composition of phenolic content together with the antioxidant activity of the flour. Progressive microwave treatment of TGNs resulted in flours with darker colors and reduced pasting parameters. Structural modification of starch granules, protein denaturation, and starch-protein complexes occasioned by microwave treatment were evidenced in the functional group analysis, including morphological agglomeration, increased particle size, and thermal properties. Treatment also enhanced the microbiological qualities of flour after 8 weeks of storage. This study shows that microwave treatment produces excellent physical modifications that lead to improvements in the nutritional, functional, sensory, and color properties, and safety attributes of TGN flour for food application. This is a development that could present opportunities for novel food formulation by the food industry and related industries. © 2024 Society of Chemical Industry.

Photocatalytic Synthesis of β-Keto Primary Chlorides by Selective Chlorocarbonylation of Olefins.

Functionalized primary alkyl chlorides are precursors to a plethora of scaffolds but their access from chemical feedstocks remains challenging. Herein, we report a concise dual Ni/photoredox catalytic protocol for regioselective chlorocarbonylation of unactivated alkenes that enables rapid access to β-keto primary chlorides. The catalytic process features an extensive substrate scope, scalability and functional group tolerance. The Ni/photocatalytic Cl⋅ generation and subsequent cross-coupling is implicated for the process based on the control experiments and DFT study. The synthetic utility of the protocol has been further corroborated through functionalization of complex substrates and modifications of the product.

Photocatalytic Synthesis of β‐Keto Primary Chlorides by Selective Chlorocarbonylation of Olefins

AbstractFunctionalized primary alkyl chlorides are precursors to a plethora of scaffolds but their access from chemical feedstocks remains challenging. Herein, we report a concise dual Ni/photoredox catalytic protocol for regioselective chlorocarbonylation of unactivated alkenes that enables rapid access to β‐keto primary chlorides. The catalytic process features an extensive substrate scope, scalability and functional group tolerance. The Ni/photocatalytic Cl⋅ generation and subsequent cross‐coupling is implicated for the process based on the control experiments and DFT study. The synthetic utility of the protocol has been further corroborated through functionalization of complex substrates and modifications of the product.

Design of a Circularly Polarized Planar Monopole Antenna with a Simplified Radiator Structure for UWB Applications

The demand for wideband circularly polarized (CP) antennas in wireless communication applications has been increasing, given that it offers reliable signals with reduced interference. In particular, planar monopole antennas are a popular choice for use in CP applications due to their compact size and ease of integration. However, achieving CP characteristics often requires complex modifications, an increased antenna size, and design complexity. To address these challenges, this study proposes a simplified radiator structure modification for CP planar monopole antennas and validates the performance of the proposed antenna for ultra-wideband (UWB) applications by conducting both frequency-domain and time-domain analyses. The size of the proposed antenna is 34 mm × 41 mm × 1.6 mm, with FR-4 as the substrate. Both the -10 dB &lt;i&gt;S&lt;/i&gt;&lt;sub&gt;11&lt;/sub&gt; bandwidth and 6 dB axial ratio axial ratio is 3.46–5.5 GHz, with the radiation patterns in the frequency range of interest being omni-directional. The proposed UWB CP antenna also yields decent antenna performance in time-domain analyses, such as the antenna fidelity factor and the system fidelity factor.

On the Performance of Malleable APGAS Programs and Batch Job Schedulers

Malleability—the ability for applications to dynamically adjust their resource allocations at runtime—presents great potential to enhance the efficiency and resource utilization of modern supercomputers. However, applications are rarely capable of growing and shrinking their number of nodes at runtime, and batch job schedulers provide only rudimentary support for such features. While numerous approaches have been proposed to enable application malleability, these typically focus on iterative computations and require complex code modifications. This amplifies the challenges for programmers, who already wrestle with the complexity of traditional MPI inter-node programming. Asynchronous Many-Task (AMT) programming presents a promising alternative. In AMT, computations are split into many fine-grained tasks, which are processed by workers. This makes transparent task relocation via the AMT runtime system possible, thus offering great potential for enabling efficient malleability. In this work, we propose an extension to an existing AMT system, namely APGAS for Java. We provide easy-to-use malleability programming abstractions, requiring only minor application code additions from programmers. Runtime adjustments, such as process initialization and termination, are automatically managed by our malleability extension. We validate our malleability extension by adapting a load balancing library handling multiple benchmarks. We show that both shrinking and growing operations cost low execution time overhead. In addition, we demonstrate compatibility with potential batch job schedulers by developing a prototype batch job scheduler that supports malleable jobs. Through extensive real-world job batches execution on up to 32 nodes, involving rigid, moldable, and malleable programs, we evaluate the impact of deploying malleable APGAS applications on supercomputers. Exploiting scheduling algorithms, such as FCFS, Backfilling, Easy-Backfilling, and one exploiting malleable jobs, the experimental results highlight a significant improvement regarding several metrics for malleable jobs. We show a 13.09% makespan reduction (the time needed to schedule and execute all jobs), a 19.86% increase in node utilization, and a 3.61% decrease in job turnaround time (the time a job takes from its submission to completion) when using 100% malleable job in combination with our prototype batch job scheduler compared to the best-performing scheduling algorithm with 100% rigid jobs.

A receiver-driven transport protocol using differentiated algorithms for differential congestion in datacenters

With the continuous development of applications, data centers run application traffic from various service providers, and the requirements for data center networks are also increasing. Congestion control has always been a hot topic of discussion. Prevalent sender-driven transport protocols require adjusting their sending rate after network congestion occurs, and the long feedback delay makes them susceptible to a buffer overflow. Therefore, receiver-driven transport protocols are proposed, and the receiver adopts credits to allocate downlink bandwidth to overcome network congestion. This type of scheme solves last-hop congestion and reduces congestion feedback latency. However, the existing receiver-driven transport protocol is insensitive to congestion location and thus reacts inaccurately to congestion. To address this problem, this paper proposes a congestion control algorithm with congestion location awareness. In this scheme, 1) we first design an ECN-based congestion detection method to achieve lightweight congestion types awareness, i.e., instantaneous congestion and continuous congestion. 2) Based on this, we further design a differentiated transmission control strategy. For instantaneous congestion, we adopt adaptive backoff and delay control algorithms. For continuous congestion, we employ a rate control algorithm to reduce in-network congestion. This does not require complex modifications to the switch. In our evaluation, the overall average flow completion time (FCT) of DCC is up to 21%, 89%, 1.5×, and 3.4× better than Homa, ExpressPass, Timely, and pHost, respectively.

4-(Azolyl)-Benzamidines as a Novel Chemotype for ASIC1a Inhibitors.

Acid-sensing ion channels (ASICs) play a key role in the perception and response to extracellular acidification changes. These proton-gated cation channels are critical for neuronal functions, like learning and memory, fear, mechanosensation and internal adjustments like synaptic plasticity. Moreover, they play a key role in neuronal degeneration, ischemic neuronal injury, seizure termination, pain-sensing, etc. Functional ASICs are homo or heterotrimers formed with (ASIC1-ASIC3) homologous subunits. ASIC1a, a major ASIC isoform in the central nervous system (CNS), possesses an acidic pocket in the extracellular region, which is a key regulator of channel gating. Growing data suggest that ASIC1a channels are a potential therapeutic target for treating a variety of neurological disorders, including stroke, epilepsy and pain. Many studies were aimed at identifying allosteric modulators of ASIC channels. However, the regulation of ASICs remains poorly understood. Using all available crystal structures, which correspond to different functional states of ASIC1, and a molecular dynamics simulation (MD) protocol, we analyzed the process of channel inactivation. Then we applied a molecular docking procedure to predict the protein conformation suitable for the amiloride binding. To confirm the effect of its sole active blocker against the ASIC1 state transition route we studied the complex with another MD simulation run. Further experiments evaluated various compounds in the Enamine library that emerge with a detectable ASIC inhibitory activity. We performed a detailed analysis of the structural basis of ASIC1a inhibition by amiloride, using a combination of in silico approaches to visualize its interaction with the ion pore in the open state. An artificial activation (otherwise, expansion of the central pore) causes a complex modification of the channel structure, namely its transmembrane domain. The output protein conformations were used as a set of docking models, suitable for a high-throughput virtual screening of the Enamine chemical library. The outcome of the virtual screening was confirmed by electrophysiological assays with the best results shown for three hit compounds.

Improving gene transfection efficiency of highly branched poly(β-amino ester)s through the in-situ conversion of inactive terminal groups

Highly branched poly(β-amino ester)s (HPAEs) have emerged as a safe and efficient type of non-viral gene delivery vectors. However, the presence of inactive terminal secondary amine groups compromises their gene transfection capability. In this study, HPAEs with similar topological structures and chemical compositions but varying numbers of terminal secondary 4-amino-1-butanol (S4) and secondary/tertiary 3-morpholinopropylamine (MPA) groups were synthesized. The results demonstrate that an increased number of secondary/tertiary MPA groups in-situ significantly enhances the DNA binding capability of HPAEs, leading to the formation of smaller HPAE/DNA polyplexes with higher zeta potential, ultimately resulting in superior gene transfection efficiency in bladder epithelial cells. This study establishes a simple yet effective strategy to maximize the gene transfection potency of HPAEs by converting the inactive terminal groups in-situ without the need for complex modifications to their topological structure and chemical composition.

An unusual dual sugar-binding lectin domain controls the substrate specificity of a mucin-type O-glycosyltransferase.

N-acetylgalactosaminyl-transferases (GalNAc-Ts) initiate mucin-type O-glycosylation, an abundant and complex posttranslational modification that regulates host-microbe interactions, tissue development, and metabolism. GalNAc-Ts contain a lectin domain consisting of three homologous repeats (α, β, and γ), where α and β can potentially interact with O-GalNAc on substrates to enhance activity toward a nearby acceptor Thr/Ser. The ubiquitous isoenzyme GalNAc-T1 modulates heart development, immunity, and SARS-CoV-2 infectivity, but its substrates are largely unknown. Here, we show that both α and β in GalNAc-T1 uniquely orchestrate the O-glycosylation of various glycopeptide substrates. The α repeat directs O-glycosylation to acceptor sites carboxyl-terminal to an existing GalNAc, while the β repeat directs O-glycosylation to amino-terminal sites. In addition, GalNAc-T1 incorporates α and β into various substrate binding modes to cooperatively increase the specificity toward an acceptor site located between two existing O-glycans. Our studies highlight a unique mechanism by which dual lectin repeats expand substrate specificity and provide crucial information for identifying the biological substrates of GalNAc-T1.

Impact of Copper(II)-Imidazole Complex Modification on Polycrystalline TiO2: Insights into Formation, Characterization, and Photocatalytic Performance

Micrometer-sized polycrystalline anatase particles are widely used in materials and life sciences, serving as essential components in photocatalytic materials. The ability to tailor their composition, shape, morphology, and functionality holds significant importance. In this study, we identified and examined the non-destructive route of Copper(II) implantation at the surface of polycrystalline TiO2. The [Cu(en)(Im)2]2+ complex ion demonstrated a remarkable affinity to concentrate and bind with the semiconductor’s surface, such as anatase, forming a surface-bound adduct: ≡TiO2 + [Cu(en)(Im)2]2+ → ≡TiO2//[Cu(en)(Im)2]2+. The misalignment of Fermi levels in TiO2//[Cu(en)(Im)2]2+ triggered electron transfer, leading to the reduction of the metal center, releasing Copper(I) in the process. Although less efficient, the released Copper(I) encountered a highly favorable environment, resulting in the formation of the surface complex TiO2:CuIIsc. The implanted Cu(I) was converted back into Cu(II) due to re-oxidation by dissolved oxygen. The penetration of the metal ion into the surface level of the polycrystalline TiO2 lattice was influenced by surface residual forces, making surface grafting of the Cu(II) ion inevitable due to surface chemistry. FTIR, UV–vis, Raman, XRD, EPR, and surface morphological (SEM, EDAX, and HRTEM) analyses identified the typical surface grafting of the Cu(II) cluster complex on the anatase surface matrix. Moreover, the XRD results also showed the formation of an impure phase. The TiO2 polycrystalline materials, modified by the incorporation of copper complexes, demonstrated an enhanced visible-light photocatalytic capability in the degradation of Rhodamine B dye in aqueous solutions. This modification significantly improved the efficiency of the photocatalytic process, expanding the applicability of TiO2 to visible light wavelengths. These studies open up the possibility of using copper complexes grafted on metal oxide surfaces for visible-light active photocatalytic applications. Moreover, this investigation not only showcases the improved visible-light photocatalytic behavior of copper-modified TiO2 polycrystalline materials, but also underscores the broader implications of this improvement in the advancement of sustainable and efficient water treatment technologies.

One-Pot Fabrication of Supramolecular Synthetic Protein Hydrogel with Tissue-like Integrated Dynamic Features.

Protein-incorporated soft networks have received remarkable attention during the past several years. They possess desirable properties similar to native tissues and organs and exhibit unique advantages in applications. However, fabrication of protein-based hydrogels usually suffers from complex protein mutation and modification or chemical synthesis, which limited the scale and yield of production. Meanwhile, the lack of rationally designed noncovalent interactions in networks may result in a deficiency of the dynamic features of materials. Therefore, a highly efficient method is needed to include supramolecular interactions into protein hydrogel to generate a highly dynamic hydrogel possessing integrated tissue-like properties. Here, we report the design and construction of native protein-based supramolecular synthetic protein hydrogels through a simple and efficient one-pot polymerization of acrylamide and ligand monomers in the presence of a ligand-binding protein. The supramolecular interactions in the network yield integrated dynamic properties, including remarkable stretchability over 10,000% of their original length, ultrafast self-healing abilities within 3-4 s, tissue-like fast stress relaxation, satisfactory ability of adhesion to different living and nonliving substrates, injectability, and high biocompatibility. Furthermore, this material demonstrated potential as a biosensor to monitor small finger movements. This strategy provides a new avenue for fabricating synthetic protein hydrogels with integrated features.

Age-Dependent Changes in Nrf2/Keap1 and Target Antioxidant Protein Expression Correlate to Lipoxidative Adducts, and Are Modulated by Dietary N-3 LCPUFA in the Hippocampus of Mice.

The brain has a high metabolism rate that may generate reactive oxygen and nitrogen species. Consequently, nerve cells require highly efficient antioxidant defenses in order to prevent a condition of deleterious oxidative stress. This is particularly relevant in the hippocampus, a highly complex cerebral area involved in processing superior cognitive functions. Most current evidence points to hippocampal oxidative damage as a causal effect for neurodegenerative disorders, especially Alzheimer's disease. Nuclear factor erythroid-2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) is a master key for the transcriptional regulation of antioxidant and detoxifying systems. It is ubiquitously expressed in brain areas, mainly supporting glial cells. In the present study, we have analyzed the relationships between Nrf2 and Keap1 isoforms in hippocampal tissue in response to aging and dietary long-chain polyunsaturated fatty acids (LCPUFA) supplementation. The possible involvement of lipoxidative and nitrosative by-products in the dynamics of the Nrf2/Keap1 complex was examined though determination of protein adducts, namely malondialdehyde (MDA), 4-hydroxynonenal (HNE), and 3-nitro-tyrosine (NTyr) under basal conditions. The results were correlated to the expression of target proteins heme-oxygenase-1 (HO-1) and glutathione peroxidase 4 (GPx4), whose expressions are known to be regulated by Nrf2/Keap1 signaling activation. All variables in this study were obtained simultaneously from the same preparations, allowing multivariate approaches. The results demonstrate a complex modification of the protein expression patterns together with the formation of adducts in response to aging and diet supplementation. Both parameters exhibited a strong interaction. Noticeably, LCPUFA supplementation to aged animals restored the Nrf2/Keap1/target protein patterns to the status observed in young animals, therefore driving a "rejuvenation" of hippocampal antioxidant defense.

Epigenetic regulation in cancer.

Epigenetic modifications are defined as heritable changes in gene activity that do not involve changes in the underlying DNA sequence. The oncogenic process is driven by the accumulation of alterations that impact genome's structure and function. Genetic mutations, which directly disrupt the DNA sequence, are complemented by epigenetic modifications that modulate gene expression, thereby facilitating the acquisition of malignant characteristics. Principals among these epigenetic changes are shifts in DNA methylation and histone mark patterns, which promote tumor development and metastasis. Notably, the reversible nature of epigenetic alterations, as opposed to the permanence of genetic changes, positions the epigenetic machinery as a prime target in the discovery of novel therapeutics. Our review delves into the complexities of epigenetic regulation, exploring its profound effects on tumor initiation, metastatic behavior, metabolic pathways, and the tumor microenvironment. We place a particular emphasis on the dysregulation at each level of epigenetic modulation, including but not limited to, the aberrations in enzymes responsible for DNA methylation and histone modification, subunit loss or fusions in chromatin remodeling complexes, and the disturbances in higher-order chromatin structure. Finally, we also evaluate therapeutic approaches that leverage the growing understanding of chromatin dysregulation, offering new avenues for cancer treatment.

Fully Magnetically Levitated Durable Biventricular Assist Device Insertion

Durable mechanical circulatory support options for patients with biventricular failure are limited. One emerging strategy is the use of two fully magnetically levitated durable ventricular assist devices (HeartMate 3s) in a biventricular configuration. The use of a HeartMate 3 as a right ventricular assist device (RVAD) requires several complex technical modifications. Here, we provide step-wise detailed figures and a comprehensive description of bilateral HeartMate 3 insertion, with a particular focus on right atrial inflow cannulation for the RVAD. Potential pitfalls and solutions are also described.

Complex Modification of the Surface Layer of a High-Entropy Al–Cr–Fe–Co–Ni Alloy by Electron-Ion-Plasma Treatment

Complex Modification of the Surface Layer of a High-Entropy Al–Cr–Fe–Co–Ni Alloy by Electron-Ion-Plasma Treatment

Nitrogen, phosphorus, and sulfur co-doped carbon nanotubes/melamine foam composite electrode for high-performance vanadium redox flow battery

The high cost and complex modification process of carbon felt electrodes limits its further popularization in vanadium redox flow batteries (VFBs). By introducing low-cost melamine foam, nitrogen, phosphorus, and sulfur co-doped carbon nanotubes/ melamine foam composite electrode (NPS-CNTs-CMF) is designed and fabricated via immersing melamine foam in a solution containing N, P, and S co-doped CNTs. The integration of modified CNTs significantly enhances the conductivity and hydrophilicity of the electrode. Moreover, the composite electrode also demonstrates outstanding electrocatalytic activity owing to the heteroatom doping that further inspired the electrocatalytic activity of CNTs. Density function theory calculations further uncover that introducing heteroatoms on CNTs not only promotes the adsorption of vanadium ions but also facilitates the electron transfer between vanadium ions and MF substrate. As a result, the battery loading with NPS-CNTs-CMF exhibits excellent battery performance, achieving energy efficiency of 80.12 % at 300 mA cm–2. Additionally, the long-term cycling stability is attained over 200 consecutive charge-discharge cycles at 300 mA cm−2. This study provides a novel melamine foam material with low cost and simple modification, and this new composite structure stimulates the development of high-performance electrodes in VFBs.

N-Alkylimidazol-5-yl-substituted Nitronyl Nitroxides and Their Mononuclear Cu(II) Complexes: Synthesis, Structure and Magnetic Properties.

A novel synthetic approach has been employed to synthesize a series of new nitronyl nitroxides: 2-(1-propyl-1H-imidazol-5-yl)- (Ln-Pr ), 2-(1-isopropyl-1H-imidazol-5-yl)- (Li-Pr ) and 2-(1-butyl-1H-imidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (Ln-Bu ). The reaction of Cu(hfac)2 with LR in a 1 : 2 ratio yields mononuclear heterospin complexes [Cu(hfac)2 (LR )2 ] (LR =Ln-Pr , Li-Pr , Ln-Bu ), which have a similar crystal structure to the "jumping" crystals [Cu(hfac)2 (LMe )2 ] that exhibit chemomechanical activity. It was shown that an increase in the alkyl substituent R leads to changes in the crystal packing of the molecules and the absence of chemomechanical activity. Furthermore, it was found that two polymorph modifications of the heterospin complex [Cu(hfac)2 (Ln-Pr )2 ] can be obtained, and magnetic properties of [Cu(hfac)2 (Ln-Pr )2 ] strongly depend on the angle between the planes of the paramagnetic fragment O•-N-C=N→O and the imidazole ring in Ln-Pr .

Direct and Detailed Site-Specific Glycopeptide Characterization by Higher-Energy Electron-Activated Dissociation Tandem Mass Spectrometry.

Glycosylation is widely recognized as the most complex post-translational modification due to the widespread presence of macro- and microheterogeneities, wherein its biological consequence is closely related to both the glycosylation sites and the glycan fine structures. Yet, efficient site-specific detailed glycan characterization remains a significant analytical challenge. Here, utilizing an Orbitrap-Omnitrap platform, higher-energy electron-activated dissociation (heExD) tandem mass spectrometry (MS/MS) revealed extraordinary efficacy for the structural characterization of intact glycopeptides. HeExD produced extensive fragmentation within both the glycan and the peptide, including A-/B-/C-/Y-/Z-/X-ions from the glycan motif and a-/b-/c-/x-/y-/z-type peptide fragments (with or without the glycan). The intensity of cross-ring cleavage and backbone fragments retaining the intact glycan was highly dependent on the electron energy. Among the four electron energy levels investigated, electronic excitation dissociation (EED) provided the most comprehensive structural information, yielding a complete series of glycosidic fragments for accurate glycan topology determination, a wealth of cross-ring fragments for linkage definition, and the most extensive peptide backbone fragments for accurate peptide sequencing and glycosylation site localization. The glycan fragments observed in the EED spectrum correlated well with the fragmentation patterns observed in EED MS/MS of the released glycans. The advantages of EED over higher-energy collisional dissociation (HCD), stepped collision energy HCD (sceHCD), and electron-transfer/higher-energy collisional dissociation (EThcD) were demonstrated for the characterization of a glycopeptide bearing a biantennary disialylated glycan. EED can produce a complete peptide backbone and glycan sequence coverage even for doubly protonated precursors. The exceptional performance of heExD MS/MS, particularly EED MS/MS, in site-specific detailed glycan characterization on an Orbitrap-Omnitrap hybrid instrument presents a novel option for in-depth glycosylation analysis.

The Artin monoid Cayley graph

In this paper, we investigate properties of the Artin monoid Cayley graph. This is the Cayley graph of an Artin group A_{\Gamma} with respect to the (infinite) generating set given by the associated Artin monoid A^+_{\Gamma} . In a previous paper, the first three authors introduced a monoid Deligne complex and showed that this complex is contractible for all Artin groups. In this paper, we show that the Artin monoid Cayley graph is quasi-isometric to a modification of the Deligne complex for A_{\Gamma} obtained by coning off translates of the monoid Deligne complex. We then address the question of when the monoid Cayley graph has infinite diameter. We conjecture that this holds for all Artin groups of infinite type. We give a set of criteria that imply infinite diameter, and using existing solutions to the word problem for large type Artin groups and 3-free Artin groups, we prove that the conjecture holds for any Artin group containing a 3-generator subgroup of one of these two types.