Molecular Dimensions Research Articles

BPNN-QSTR Models for Triazine Derivatives for Lubricant Additives

Abstract Triazine derivatives are a kind of lubricant additives with excellent tribological properties. It is of great significance to study the quantitative relationship between their chemical structure and tribological properties. In the present study, the quantitative structure tribo-ability relationships (QSTR) between 20 triazine derivatives and their respective extreme-pressure properties as lubricant additives were analyzed by the back propagation neural network (BPNN) method. The BPNN-QSTR model had satisfactory stability and predictive ability (R2 = 0.9965, R2(LOO) = 0.9195, q2 = 0.8274). The anti-wear model also yielded good predictions (R2 = 0.9757, R2(LOO) = 0.6261, q2 = 0.8022). Two- and three-dimensional structural descriptors were used to analyze molecular structures that affected extreme-pressure and anti-wear properties. The results indicate that the three-dimensional molecular dimensions and the bonding modes of the skeleton atoms in the molecules were important factors. In addition, the effects of N, P, O, and other hetero-atoms on the tribological properties were reflected in their corresponding group types and electronic structures.

Study on the Swelling Characteristics of Bamboo Based on Its Graded Hierarchical Structure

To understand the swelling characteristics of bamboo under its gradient structure, different parts of bamboo specimens have been soaked in solutions of different electrolytes. The results showed that the swelling extent of bamboo in solution is mainly influenced by chemical activity and molecular dimension of the solute. The dimensional increase in bamboo after swelling is mainly observed in the tangential and radial direction, and the largest dimensional increase as a result of swelling occurred in intermediary bamboo. High-concentration strong electrolytes will cause a certain degree of recrystallization in the bamboo specimen, especially in intermediary bamboo, resulting in an increase in its mass. In summary, the conclusion is that the removal of wax and tabaxir before swelling and the avoidance of using strong electrolytes as swelling solutions tend to improve the efficiency of swelling bamboo.

Effect of molecular dimension on gallery height, release kinetics and antibacterial activity of Zn[sbnd]Al layered double hydroxide (LDH) encapsulated with benzoate and its derivatives

This paper outlines the encapsulation of benzoate and its two derivatives i.e. para-hydroxybenzoic acid (p-BZOH) and 2-chloro-5-nitrobenzoic acid (BZCN) having antibacterial activity in between the interlayer distance of ZnAl layered double hydroxides to form an antibacterial composite material. The three reagents were successfully intercalated in between ZnAl LDH via anion-exchange mechanism. The intercalation was successfully evaluated by the increase in the basal spacing from X-ray diffraction, FTIR and thermogravimetry (TG-DTA) analysis. By variation of incoming reagents, the nature of interlayer arrangement, the tendency of binding, kinetics of release of the reagent from the inorganic lamella and bactericidal effect differ. The novel nano-composites demonstrated a distinctly enhanced bactericidal effect towards both gram positive (Staphylococcus aureus, MTCC 96) and gram negative (Escherichia coli, MTCC 739) bacterial strains having diverse rate of killing. Also the diffusion of the active molecules out of the nano-composites was found to be very slow and in a sustained manner in case of BZCN as compared to other two. Therefore these newly designed organic-inorganic fusions may offer a promising antimicrobial elucidation to the society.

A Diastereodynamic Probe Transducing Molecular Length into Chiroptical Readout.

Nature takes advantage of molecular conformational changes to express functions such as signaling across cellular membranes or allosteric protein activation. At the synthetic level, molecular recognition events have been used to induce conformational changes able to trigger functions such as catalysis or sensing. In this context, transduction of stereochemical information has been the leading strategy. In particular, stereodynamic elements have been extensively employed to amplify and/or transduce chiral information. In this article, we report a chiral supramolecular cage with two stereodynamic units, which invert their helicities according to the length of the molecular guest confined within the system. Interestingly, achiral information is transduced by the supramolecular system to different diastereomeric states that have opposite chiroptical absorptions. This is the first example in which it is possible to produce a continuous modulation of the chiroptical output of a system by varying a physical achiral molecular property (viz. molecular dimension). This phenomenon can be exploited for the establishment of novel methods to program conformational control, for the development of innovative sensors and/or for transduction of molecular properties into chiroptical information.

Asymmetric Knoevenagel‐Phospha‐Michael Tandem Reaction Synergistically Catalyzed by Achiral Silanols and Grafted Chiral Amines on Mesoporous Silica

AbstractHighly efficient and enantioselective asymmetric Knoevenagel‐phospha‐Michael tandem reactions have been achieved on bifunctional heterogeneous catalysts with inherent silanols as acidic sites and immobilized chiral amines as basic sites. Final products were afforded in yields of up to 99% and ee values of up to 99%. The effects of substituents on benzaldehyde and molecular dimensions of phosphites have also been investigated. Larger substrates can access the catalytic site inside larger mesoporous pores, thereby improving both of yield and ee of final products.

Spectroscopic Determination of the Site in MFI Zeolite where Cobalt(I) Performs Two-Electron Reduction of O2 at Room Temperature

Zeolites have well-defined pores of molecular dimensions to stabilize the molecularly dispersed reactive oxygen species (ROS) responsible for actual key intermediates in a variety of desirable cata...

Bridging Simulation Length Scales of Bottlebrush Polymers Using a Wormlike Cylinder Model

Bottlebrush polymers, formed from a linear backbone polymer with a high density of grafted side chains, are functional macromolecules useful in molecular assembly and responsive materials due to their unique physical properties. Interactions between the side chains stiffen the molecular backbone and imbue it with a molecular dimension beyond simply the polymer length, drastically altering dynamic relaxation and intrapolymer interactions. Simulation prediction of these material properties remains a challenge, however, because they specifically depend on side chain degrees of freedom that are computationally expensive to model. In this work, we use the wormlike cylinder framework to systematically map molecular features from a single-molecule hybrid Brownian dynamics and Monte Carlo (BD/MC) simulation with explicit side chains to a simple touched-bead polymer model. We use static properties from the explicit side chain simulations such as end-to-end distance and radius of gyration to parameterize the wormli...

SLAMF8, a novel biomarker for personalized immune checkpoint blockade therapy in gastrointestinal cancer.

e14078 Background: Immune checkpoint inhibitors have brought great breakthroughs in cancer therapy. Activated immune response is known to be the prerequisite for exerting immunotherapy efficacy. Epstein-Barr virus (EBV) infection is associated with longer survival in gastric cancer (GC) patients due to enhanced anti-tumor immune response, and therefore it was reportedly played an important role in modulating immune checkpoint blockade therapy efficacy. However, molecular dimensions underlying the good response to immune checkpoint inhibitors in presence of EBV infection are still unclear. The aim of this study is to identify a gene signature related to EBV induced anti-tumor immune response, and select a tag gene from this signature to predict which patients are most likely to benefit from immune checkpoint blockade therapy. Methods: Two large transcriptome datasets from Gene Expression Omnibus(GEO) database (GSE51575 and GSE62254) were used to screen gene signature for EBV infected gastric cancer tissues. We further selected genes that showed a trend towards differential co-expression independent of EBV infection status. The tag gene of this differential co-expression signature was finally identified by bioinformatics analysis. To make an external validation, we performed RNA sequencing in 20 colorectal caner (CRC) tissues and 20 GC tissues, respectively. Meanwhile, tissue microarrays of CRC cohort (36 paired tumor and normal tissues) and GC cohort (75 paired tumor and normal tissues) were used to analyze the association of SLAMF8 with CD8 protein expression by immunohistochemistry (IHC). Results: Analysis of GEO datasets indicated 788 genes as feature gene cluster for EBV-positive gastric cancer, from which 290 genes were selected to be characterized by differential co-expression in either EBV-positive or EBV-negative gastric cancers. SLAMF8 was identified as the tag gene for this differential co-expression signature. This signature, tagged by SLAMF8, was successfully validated by our RNA sequencing data in presence of its good performance in dividing CRC and GC patients into two subsets. Moreover, we observed a significant association between SLAMF8 and CD8 expression in our CRC and GC tissue samples, in terms of either mRNA or protein level. Conclusions: SLAMF8, a potential indicator for T cell‐mediated immune response induced by EBV infection, may be served as a biomarker for individualized immune checkpoint blockade therapy in gastrointestinal cancer. Further SLAMF8 guided drug sensitivity tests are warranted to validate our results.

Rediscovery of the Importance of Inorganic Synthesis Parameters in the Search for New Zeolites.

Zeolites and related crystalline microporous materials with cavities and channels of molecular dimensions are of major importance for applications ranging from ion-exchange to adsorption and to catalysis. Because their unique shape-selective properties are closely related to the size, shape, and dimensionality of the intracrystalline channels and cavities, much interest has been devoted to the discovery of novel zeolitic materials over the last several decades. As a result, a dramatic expansion in the structural domain of crystalline microporous materials, as well as in their compositional range, has been achieved. This is largely due to the development of innovative synthetic strategies, for example, organic structure-directing agent (OSDA) design, introduction of heteroatoms like Ge in OSDA-mediated zeolite synthesis, topotactic transformation of two-dimensional layered zeolite precursors, assembly-disassembly-organization-reassembly method, etc. However, although many of these methodologies are quite successful in finding unprecedented zeolite structures, the resulting materials tend to be (hydro)thermally unstable and are often commercially impractical from a manufacturing perspective because of the high cost of the OSDA and/or heteroatom employed. Therefore, we focused on inorganic synthesis parameters as the key phase selectivity factor that has received relatively little attention in the search for new industrially relevant zeolites. This Account describes our recent efforts to find previously undiscovered aluminosilicate zeolites by boosting the roles of inorganic structure-directing agents (ISDAs) in the presence of OSDAs. They include the multiple inorganic cation and excess fluoride approaches, which aim to promote a synergistic cooperation between ISDAs and/or OSDAs and thus to hold a rational design concept, although the latter is not friendly to the practical zeolite manufacturing process due to the toxicity of fluoride. Using these two approaches, we were able to synthesize not only the second generation (PST-29) and four higher generations (PST-20 (RHO-G5), PST-25 (RHO-G6), PST-26 (RHO-G7), and PST-28 (RHO-G8)) of the RHO family of embedded isoreticular zeolites but also three other novel zeolite structures (EU-12, PST-21, and PST-22). We also explored the synthesis of a number of heteroatom-containing aluminophosphate (AlPO4) molecular sieves with different framework structures and unusually high framework charge density through the cooperative structure direction of alkali metal and small OSDA cations or under wholly inorganic conditions. Although we need to clarify the nature and extent of interactions between the inorganic cations and framework components in synthesis mixtures, we believe that our synthetic concepts, shedding new light on the importance of inorganic synthesis parameters, will open a door for achieving many other novel zeolite structures and compositions.

Cation influence in adsorptive propane/propylene separation in ZIF-8 (SOD) topology

Separation of propylene/propane is one of the most challenging and energy consuming processes in the chemical industry. Propylene demand is increasing and a 99.5% purity is required for industrial purposes. Adsorption based solutions are the most promising alternatives to improve the economical/energetic efficiency of the process. Zeolitic Imidazolate Frameworks (ZIFs) combine the desired characteristics from both MOFs and zeolites: tunability and flexibility from metal organic frameworks, and exceptional thermal and chemical stability from zeolites. In order to enlighten the role of the cation in the sodalite ZIF-8 framework for propane/propylene separation, dynamic breakthrough measurements have been performed over ZIF-8(Zn), ZIF-67 (i.e. ZIF-8(Co)) and MUV-3 (i.e. ZIF-8(Fe)), all isostructural materials based on the same linker (2-methylimidazole). Cation substitution has a remarkable influence in the framework flexibility, and, consequently, in SOD-ZIF selectivity for light hydrocarbons. The differences between the crystallographic pore sizes of the material and the molecular dimensions of propane and propylene are so small, that the slightest change in the framework causes notable advantages/disadvantages in the final application. While cobalt is known to promote a more rigid framework resulting in an adsorption selectivity towards propane, iron presents the inverse effect yielding selectivity to propylene. Zinc has an intermediate effect. A threshold pressure in the isotherm is observed for propylene uptake by ZIF-67 at 273 and 298 K, and only at the lower temperature for ZIF-8. Inlet mixture composition does not highly influence the adsorptive selectivity, although it clearly affects the pure hydrocarbon recovery. Over ZIF-67 breakthrough experiments at 298 K yield a temporary pure propylene flow representing 10–15% of the amount fed. ZIF-67 is a promising candidate for propylene/propane adsorptive separation.

Nanomaterials and Chemical Modifications for Enhanced Key Wood Properties: A Review.

This work briefly reviews the research milestones in the area of wood chemical modification, focusing on acetylated and furfurylated wood which have been scaled up, and exploits the solutions that nanotechnology can offer to wood protection as an alternative green innovative approach in improving key wood properties, namely the dimensional stability when subjected to a fluctuating moisture content and a susceptibility to biodegradability by microorganisms. Recently, nanomaterials were found to be able applicable in wood science. The target is to improve some special physicochemical characteristics of wood in order to resist extreme conditions (climate, bacteria, etc.), giving an enhanced potentiality. It is well-established that the wood cell wall shows a porosity of molecular scale dimensions; this is caused by the partial filling of spaces between the microfibrils of the cellulose mainly by polyoses and lignin. The small-sized nanoparticles can deeply and effectively penetrate into the wood, altering its surface chemistry, improving its properties, and therefore, resulting in a hyper-performance product.

Anion Dependent Self-Assembly of Polynuclear Cd-Ln Schiff Base Nanoclusters: NIR Luminescent Sensing of Nitro Explosives.

Two types of polynuclear Cd-Ln complexes [CdLnL(NO3)Cl2(DMF)2] [Ln = La (1) and Nd (2)] and [Ln2CdL2(NO3)2(DMF)2](OH)2 [Ln = La (3) and Nd (4)] were constructed using a new Schiff base ligand which has a long backbone with two phenyl groups. The Schiff base ligands show a “twist” configuration in 1–4. The crystal structures show that the molecular dimensions of 3 and 4 are about 6 × 10 × 15 Å. The Cd-Nd complexes 2 and 4 exhibit the typical NIR luminescence of Nd3+. Interestingly, 4 shows the luminescent sensing of nitro explosives and exhibits a high sensitivity to 2-nitrophenol at the ppm level.

Performance of ASP compound systems and effects on flooding efficiency

Based on practical needs of oil fields, the viscosity, interfacial tension, static absorption, phase behaviors, molecular clew dimension (Dh), molecular configuration and flooding effect of the alkali/surfactant/polymer (ASP) systems were studied by instrumental analysis and physical modeling. The mechanisms of enhanced oil recovery were also discussed. As alkali concentration increased, the viscosity, interfacial tension and Dh of ASP decreased. As surfactant concentration increased, the viscosity and Dh increased, while the interfacial tension first decreased and then rose. The viscosity, interfacial tension and Dh of weak-alkali ASP all surpassed those of the strong-alkali ASP. The saturated absorption quantity of ASP ranked as surfactant > alkali > polymer. The saturated adsorption quantity and the ability to reduce the surfactant adsorption loss of the strong alkali were both higher, but the ability to reduce polymer adsorption loss was lower, compared with the weak alkali. As the concentrations of alkali and surfactant rose, the stability of emulsions was enhanced. The effect of alkali on the polymer molecular aggregation surpassed that of the surfactant. Physical modeling showed as the viscosity of the flooding agent rose, the recovery rate of weak-alkali ASP increased by 22.0% under the conditions of 1.2 wt% alkali, 0.3 wt% surfactant and 2500 mg/L polymer. The contribution rate to the recovery efficiency of A compound flooding ranked as the extended swept volume effect of the polymer (αp) > displacement effect (β) > the extended swept volume of emulsification (αe). The results were αp = 73.5%, β = 19.9%, αe = 6.6% (weak-alkali ASP); αp = 68.5%, β = 23.0%, αe = 8.4% (strong-alkali ASP).

Beyond the TCR, Antigen Discrimination in T Cells Continues in the LAT:GRB2:SOS Protein Condensate

T cells activate in response to a stochastic series of single molecule binding events between T cell receptors (TCRs) and peptide ligands presented on major histocompatibility complexes (pMHCs) accumulated at a cell-cell interface. Discrimination between ligands with subtly different affinities ensures selective and robust immunological responses upon TCR triggering. Formation of protein condensates based on the scaffolding protein Linker for Activation of T cells (LAT) is a key intermediate step in TCR signaling. LAT is multi-phosphorylated on tyrosine residues by the kinase, ZAP70, which is activated by triggered TCRs. The phosphotyrosines recruit Grb2, which, via interactions with the multivalent GEF, SOS, forms an extended LAT:Grb2:SOS assembly that resembles a phase transition. We mapped single pMHC:TCR binding events in T cells expressing fluorescent protein-tagged LAT and show that LAT assemblies are discrete and have characteristic features that are independent of the originating binding event. Furthermore, LAT assemblies can become spatially uncoupled from the pMHC:TCR complex. These individual assemblies are capable of deforming the plasma membrane and creating local domains that may participate in protein segregation or control reaction kinetics. The probability of LAT assembly is a function of the pMHC affinity, suggesting a second layer of kinetic proofreading that exists beyond the triggered TCR. We recently introduced a molecular impulse-response assay which maps pMHC:TCR binding events to early T cell activation. Results here argue that LAT assemblies may confer a molecular memory that connects a series of spatiotemporally correlated binding events to cellular decision-making. By extending the impulse-response assay, we show that activating cells experience a characteristic, fast rate of LAT assembly. Taken together, we present new molecular dimensions to T cell activation that could provide actionable therapeutic insights.

Computational assessment of the cellular dosimetry and microdosimetry of the gadolinium electrons released during neutron capture therapy

One of the challenges in radiobiology is the determination of the dose of Auger electrons in cellular-molecular dimensions and evaluation of their relative biological effectiveness (RBE). In this study, we try to assess the cellular dosimetry and microdosimetry of the internal conversion (IC) and Auger electrons released during Gadolinium-157 neutron capture reaction (157GdNCR) using the low-energy physics models included in Geant4 toolkit and MCNPX code. The results show that the MCNPX code does not have reliable results for the cellular dosimetry of low-energy electrons compared to the validated low-energy Geant4 physics models. Although the use of the Geant4-DNA models is a necessity in microdosimetric calculations, due to the time-consuming run of the Geant4-DNA models in the cellular dosimetry calculations, the use of Geant4-Penelope and Geant4-Livermore models can lead to the quick and reliable results. The results show that, with appropriate selection of physical parameters, the results of small-scale microdosimetry calculated using the CH models in Geant4 approach the results of Geant4-DNA. With regard to the cellular dosimetry results, the amount of the absorbed dose in the nucleus of a cell is strongly dependent on the distribution of Gd in the different compartments of the cell. The cross-dose in the nucleus from the Gd electrons released in adjacent cells is comparable to the self-dose of the nucleus to nucleus and noteworthy to destroy the quiescent cancer cells that do not accumulate Gd. The microdosimetry results show that, unlike the absorbed dose in DNA, RBE is not much dependent on the Gd distribution relative to the DNA within the molecular dimensions. If Gd is distributed at the center of the DNA, the absorbed dose of Gd electrons in the DNA (246 kGy) with a quality-factor-equivalent RBE of 7.93 is sufficiently large for the double-strand breaks (DSBs) of the DNA.

The functionality of the hybrid systems driven by molecular dimension of the guest copper Schiff‐base complexes entrapped in Zeolite‐Y

On encapsulation inside the supercage of zeolite‐Y planar Cu (II)–Schiff base complexes show the modified structural, optical and functional properties. The electronic effect of the different substituent groups present in the catalyst plays the decisive role towards their reactivity in the homogeneous phase but after the encapsulation in zeolite Y, reactivity is mainly governed by the molecular dimensions of the guest complexes rather than the electronic factor of the substituent groups attached on them. These systems are well characterized with the help of different characterization tools like XRD analysis, SEM ‐ EDX, AAS, FTIR, XPS, DSC, TGA, BET and UV–Visible spectroscopy and the comparative optical and catalytic studies have provided a rational explanation of enhanced reactivity of zeolite encapsulated metal complexes for various oxidation reactions compared to their corresponding solution states.

In Vitro Cytotoxicity and In Vivo Antitumor Efficacy of Tetrazolato-Bridged Dinuclear Platinum(II) Complexes with a Bulky Substituent at Tetrazole C5

Tetrazolato-bridged dinuclear platinum(II) complexes ([{cis-Pt(NH3)2}2(μ-OH)(μ-5-R-tetrazolato-N2,N3)]2+; tetrazolato-bridged complexes) are a promising source of next-generation platinum-based drugs. β-Cyclodextrin (β-CD) forms inclusion complexes with bulky organic compounds or substituents, changing their polarity and molecular dimensions. Here, we determined by 1H-NMR spectroscopy, the stability constants for inclusion complexes formed between β-CD and tetrazolato-bridged complexes with a bulky, lipophilic substituent at tetrazole C5 (complexes 1–3, phenyl, n-nonyl, and adamantyl substitution, respectively). We then determined the in vitro cytotoxicity and in vivo antitumor efficacy of complexes 1–3 against the Colon-26 colorectal cancer cell line in the absence or presence of equimolar β-CD. Compared with the platinum-based anticancer drug oxaliplatin (1R,2R-diaminocyclohexane)oxalatoplatinum(II)), complex 2 had similar cytotoxicity, complex 3 was moderately cytotoxic, and complex 1 was the least cytotoxic. The cytotoxicity of the complexes decreased in the presence of β-CD. When we examined the in vivo antitumor efficacy of complexes 1–3 (10 mg/kg) against homografted Colon-26 colorectal tumors in male BALB/c mice, they showed a relatively low tumor growth inhibition compared with oxaliplatin. However, in the presence of β-CD, complex 3 had higher in vivo antitumor efficacy than oxaliplatin, suggesting a new direction for future research into tetrazolato-bridged complexes with high in vivo antitumor activity.

Cyclosis-mediated intercellular transmission of photosynthetic metabolites in Chara revealed with chlorophyll microfluorometry.

Symplastic interconnections of plant cells via perforations in adjoining cell walls (plasmodesmata) enable long-distance transport of photoassimilates and signaling substances required for growth and development. The pathways and features of intercellular movement of assimilates are often examined with fluorescent tracers whose molecular dimensions are similar to natural metabolites produced in photosynthesis. Chlorophyll fluorescence was recently found to be a sensitive noninvasive indicator of long-distance intracellular transport of physiologically produced photometabolites in characean internodes. The present work shows that the chlorophyll microfluorometry has a potential for studying the cell-to-cell transport of reducing substances released by local illumination of one internode and detected as the fluorescence increase in the neighbor internode. The method provides temporal resolution in the time frame of seconds and can be used to evaluate permeability of plasmodesmata to natural components released by illuminated chloroplasts. The results show that approximately one third of the amount of photometabolites released into the streaming cytoplasm during a 30-s pulse of local light permeates across the nodal complex with the characteristic time of ~10s. The intercellular transport was highly sensitive to moderate elevations of osmolarity in the bath solution (150mM sorbitol), which contrasts to the view that only transnodal gradients in osmolarity (and internal hydrostatic pressure) have an appreciable influence on plasmodesmal conductance. The inhibition of cell-to-cell transport was reversible and specific; the sorbitol addition had no influence on photosynthetic electron transport and the velocity of cytoplasmic streaming. The conductance of transcellular pores increased in the presence of the actin inhibitor cytochalasin D but the cell-to-cell transport was eventually suppressed due to the deceleration and cessation of cytoplasmic streaming. The results show that the permeability of plasmodesmata to low-molecular photometabolites is subject to upregulation and downregulation.

Complexity of dissolved organic matter in the molecular size dimension: insights from coupled size exclusion chromatography electrospray ionisation mass spectrometry.

This paper investigates the relationship between apparent size distribution and molecular complexity of dissolved organic matter from the natural environment. We used a high pressure size exclusion chromatography (HPSEC) method coupled to UV-Vis diode array detection (UV-DAD) and electrospray ionisation mass spectrometry (ESI-MS) in order to compare the apparent size of natural organic matter, determined by HPSEC-UV and the molecular mass determined online by ESI-MS. We found that there was a clear discrepancy between the two methods, and found evidence for an important pool of organic matter that has a strong UV absorbance and no ESI-MS signal. Contrary to some previous research, we found no evidence that apparently high molecular weight organic matter is constituted by aggregates of low molecular weight (<1000 Da) material. Furthermore, our results suggest that the majority of apparent size variability within the ESI ionisable pool of organic matter is due to secondary interaction and exclusion effects on the HPSEC column, and not true differences in hydrodynamic size or intermolecular aggregation.

Can one determine the density of an individual synthetic macromolecule?

Dendronized polymers (DPs) are large and compact main-chain linear polymers with a cylindrical shape and cross-sectional diameters of up to ∼15 nm. They are therefore considered molecular objects, and it was of interest whether given their experimentally accessible, well-defined dimensions, the density of individual DPs could be determined. We present measurements on individual, deposited DP chains, providing molecular dimensions from scanning and transmission electron microscopy and mass-per-length values from quantitative scanning transmission electron microscopy. These results are compared with density values obtained from small-angle X-ray scattering on annealed bulk specimen and with classical envelope density measurements, obtained using hydrostatic weighing or a density gradient column. The samples investigated comprise a series of DPs with side groups of dendritic generations g = 1-8. The key findings are a very large spread of the density values over all samples and methods, and a consistent increase of densities with g over all methods. While this work highlights the advantages and limitations of the applied methods, it does not provide a conclusive answer to the question of which method(s) to use for the determination of densities of individual molecular objects. We are nevertheless confident that these first attempts to answer this challenging question will stimulate more research into this important aspect of polymer and soft matter science.