Single Chain Research Articles

Quantum Heat Engines with Spin‐Chain‐Star Systems

AbstractThis study investigates a theoretical model of a Quantum Otto Cycle (QOC) that utilizes a working fluid spin‐chain‐star model. The system consists of a central atom interacting with multiple Heisenberg spin chains. Employing unitary transformations, the spin‐chain‐star system is transformed into a spin‐star model. The work done and heat transferred for three distinct working fluid configurations: the , , and cases are discussed. The efficiency of the heat engine is examined, and a comparative study between the efficiencies of the three configurations is presented. The study assumes two interaction scenarios for the central atom: either with a single chain (resulting in a two‐qubit system after transformation) or with three Heisenberg chains. The results demonstrate that increasing the ratio between the central atom's frequency in the hot bath and the cold bath leads to an enhancement in positive work performed for the and cases. In the case, the magnitude of this enhancement exhibits a dependence on the system's temperature. The QOC employing the configuration working fluid exhibits superior efficiency compared to the other two configurations. Moreover, increasing the central atom's relative frequency improves efficiency for all three cases.

Determining key mammalian species and food web robustness across different land cover vegetation using network analysis

Abstract. Risdiyanto I, Santosa Y, Santoso N, Sunkar A. 2024. Determining key mammalian species and food web robustness across different land cover vegetation using network analysis. Biodiversitas 25: 3175-3190. The ecosystem's food web depicts the intricate energy flow and complex interactions among its diverse organisms. Organisms are not confined to single trophic levels or food chains; they establish multiple food connections with other organisms within the ecosystem. This study aims to identify critical mammalian species and assess the robustness of various ecosystem types, considering the diversity of species presence, through food web analysis. Computational graphic-based network analysis is employed to achieve this goal. Ecosystem types, categorized by their land cover, include plantation/agricultural forests, Bushes and shrubss, forests, and mixed landscapes. Network centrality metrics such as degree, closeness, betweenness, and eigenvector centrality are utilized to evaluate the presence of key species and ecosystem robustness. The relative contribution of mammalian species as connectors and regulators of energy flow in the food web ranges from 8-23% of all nodes involved. Key mammalian species are classified into ecosystem stability and sustainability keys. In Bushes and shrubss ecosystems, key species predominantly consist of mammalian predator species that are crucial for maintaining ecosystem stability through population control. Conversely, in other ecosystems, key species are primarily connectors, ensuring the sustained energy flow. The most resilient food webs are observed in Bushes and shrubss and mixed ecosystems due to their higher biomass growth rates and abundant presence of mammalian species. Utilizing food web analysis can significantly contribute to species and ecosystem conservation efforts by offering a comprehensive understanding of interspecies interactions, food web structures, and ecosystem dynamics.

Iraqi patients with a single-nucleotide polymorphism of interleukin-10 -1082G/A and interleukin-6 -174G/C susceptibility to asthma

The effects of genetic variations in the IL-10 -1082G/A gene and IL-6 -174G/C gene, as well as the genotypes and alleles linked to the prevalence of asthma disease, were investigated using a molecular and immunological study. Between October 2018 and the end of July 2020, 40 healthy individuals (20 females and 20 males) served as a control group for the study, which involved 50 asthmatic patients (31 females and 19 males) at the Allergy Centre, Al-Anbar Teaching Hospital, in Al-Anbar City. The study used the Single Specific Primer-Polymerase Chain Reaction (SSP-PCR) technique to show that the single nucleotide polymorphisms IL-10 -1082G/A and IL-6 -174G/C had a considerably high prevalence rate (P<0.05) among asthma case and that there was an association between the polymorphism and the asthma risk. The findings indicate that asthma patients had considerably higher (P<0.05) IL-10 A alleles and heterozygous GA genotypes (1082G/A) compared to the control group. Genetic variations affecting IL-10 production and the genotypes affecting IL-10 serum levels are associated with the occurrence of asthma and are attributed to the IL-10 -1082G/A promoter gene polymorphism. There was a strong correlation between cytokine levels, of disease development, and the genotypes of the AA and AG genes, indicating that IL-10 -1082A/G predisposition to asthma may be influenced by the gene promoter polymorphism. Asthma development and immunological markers (IL-10) are substantially correlated. One theory links allergic rhinitis to both the development of asthma and its risk. Inducing long-term immunological and clinical tolerance in patients was a good use of HDM immunotherapy. The current study's findings indicate a substantial difference between the asthma patients and the control group in terms of gene type and allele frequency of the IL-6 -174G/C polymorphism. The patients exhibited a higher prevalence of the G allele and the GG homozygous genotype than the control group. Therefore, it was shown that those with GG genotypes had a 2-fold increased probability of having asthma, indicating that patients were more prone to the condition.

Human leukocyte antigen HLA-B*57:01 status in HIV-1 patients developing hypersensitivity reactions in Benin: a pilot study

BackgroundAntiretroviral drugs in people living with HIV-1 (PLHIV-1) often trigger side effects which may lead to discontinuation or failure of treatment. Human Leukocyte Antigen B*57:01 (HLA-B*57:01) allele is known to predict hypersensitivity reactions to Abacavir. Very few data are available on the prevalence of HLA-B*57:01 allele in PLHIV-1 in African countries. This study aimed to screen for HLA-B*57:01 allele in PLHIV-1 in Benin.MethodsThis pilot study was carried out on one hundred ten PLHIV-1 enrolled in two health facilities in Benin. Socio-demographic and clinical data were collected. Biological data were determined and HLA-B*57:01 allele was genotyped, using Single Specific Primer-Polymerase Chain Reaction in blood samples.Results70% of participants were female. PLHIV-1 were under TDF + 3TC + DTG (47.2%) or TDF + 3TC + EFV (57.3%). Their median age was 41 [36-48.75] years and the average CD4 + T cell count was 249 [130-381.25] cells/µl. The average viral load in treatment failure PLHIV-1 was 4.7 [3.9–5.2] Log10. At the inclusion date, twenty-nine (26.4%) PLHIV-1 under TDF + 3TC + EFV have developed hypersensitivity reactions. None of 110 patients had shown HLA-B*5701 allele.ConclusionOur study revealed that HLA-B*57:01 allele was very rare in PLHIV-1 in Benin, suggesting that its screening before starting the Abacavir regimen did not seem necessary.

Atomically precise inorganic helices with a programmable irrational twist.

Helicity in solids often arises from the precise ordering of cooperative intra- and intermolecular interactions unique to natural, organic or molecular systems. This exclusivity limited the realization of helicity and its ensuing properties in dense inorganic solids. Here we report that Ga atoms in GaSeI, a representative III-VI-VII one-dimensional (1D) van der Waals crystal, manifest the rare Boerdijk-Coxeter helix motif. This motif is a non-repeating geometric pattern characterized by 1D face-sharing tetrahedra whose adjacent vertices are rotated by an irrational angle. Using InSeI and GaSeI, we show that the modularity of 1D van der Waals lattices accommodates the systematic twisting of a periodic tetrahelix with a 41 screw axis in InSeI to an infinitely extending Boerdijk-Coxeter helix in GaSeI. GaSeI crystals are non-centrosymmetric, optically active and exfoliable to a single chain. These results present a materials platform towards understanding the origin and physical manifestation of aperiodic helicity in low-dimensional solids.

Instability of single polymer chain in an electroelastic problem

Under electric loading produced by compliant electrodes, a dielectric elastomer is prone to material instabilities which, in a microstructural level, may connect to single polymer chain instability. To reveal if such connection exists, we aim to use an electroelastic energy model for single polymer chain to study the chain instability. We approximate curvature shape of the chain under the electric loading by using trigonometry series in a spatial coordinate. The Rayleigh–Ritz method is then applied to solve the energy equation formed by the trigonometry series. We demonstrate in the numerical examples that the instability of the chain may occur at the value of electric field with corresponding configuration of the chain close to its full length.

Comparison of single-chain variable fragments and monoclonal antibody against dihydroartemisinin

Immunoassay relies on antibodies, but traditional antibodies such as monoclonal antibody (mAb) require animal immunization and complex procedures. Single-chain variable fragment (scFv) becomes a potential alternative to mAb with advantages of the low cost, rapid and easy prepared. In the present study, we prepared scFvs against dihydroartemisinin (DHA) based on E. coli and HEK293T cell expression system, named MBP-scFv and scFv-Fc, respectively. Their properties were compared with the parent mAb. The calculated affinity constants of mAb, MBP-scFv and scFv-Fc were 2.1 × 108 L mol−1, 2.2 × 107 L mol−1 and 1.6 × 108 L mol−1, respectively. The half inhibitory concentration (IC50) of mAb, MBP-scFv and scFv-Fc were 1.16 ng mL−1, 2.15 ng mL−1 and 6.57 ng mL−1, respectively. Both the scFv showed less sensitive than the mAb based on the IC50. The cross-reactivities of MBP-scFv for artemisinin and artesunate exhibited similarities to the mAb, yet the cross-reactivities of scFv-Fc for these compounds exceeded those of the mAb significantly. The stability of the scFvs was ascertained to be maintained for over 5 days at room temperature, and for more than a month at both 4 °C and − 20 °C. After that, the indirect competitive enzyme-linked immunosorbent assays (icELISAs) based on the scFv from E. coli were used to detect the DHA content in eight drug samples, and the result was consistent with ultra-performance liquid chromatography simultaneously. Although scFv can be used for quantitative determination of drugs, but it still cannot completely replace mAb in immunoassay without evolution and modification.

Effect of sequential tasks in the case studies of business English textbooks on fostering critical thinking based on cognitive load theory

There is a consensus that case studies in Business English class are helpful to foster critical thinking, but little research has been done to explore how case studies facilitate it. To bridge the gap, the present study uses the revised Bloom’s taxonomy as a tool to qualitatively and quantitatively investigate the effect of case studies in Market Leader textbooks on fostering critical thinking based on cognitive load theory. First, the presence of six cognitive levels targeted in the tasks is examined to see how case studies sequence their tasks according to the increase of cognitive complexity. Secondly, the scaffoldings distributed across the sequential tasks are explored to investigate how well they impose appropriate amount of cognitive load on students. Although six cognitive levels are found, there is an inappropriate administration of task scaffolding in a single task or task chain, leading to insufficient or superficial scaffolds and thus inducing high level of cognitive load for students to develop critical thinking. Accordingly, case study writers and teachers are recommended, when designing and adapting sequential tasks, to consider systematic inculcation of cognitive levels among tasks and proper administration of scaffolding with regard to the aspects of task input, conditions, progress and outcome so that a balanced level of cognitive load aligned with the state of working memory capacity of students can be achieved for fostering critical thinking.

Study on the spectral characteristics and chemical structure of Taixi Anthracite

Taixi anthracite is a rare form of coal in both China and the world, characterized by low ash, sulfur, phosphorus, high carbon content, conductivity, and calorific value. Our team employed a solid-phase microwave method [1] to graphitize Taixi anthracite and graft it with natural rubber to create a composite with outstanding properties. However, since the molecular structure of Taixi anthracite was unknown, establishing a molecular model for the reaction becomes crucial for the functionalization of anthracite. In this study, By combining elemental analysis, nuclear magnetic resonance carbon spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, the molecular carbon content of Taixi anthracite is 89 %, the XBP value is 0.37, and the chemical formula of the lowest relative molecular weight of Taixi anthracite is C181H77O4NS0.1. The results of computer simulation show that Taixi anthracite is assembled into coal macromolecular structure by 10 molecular structure units of 5 kinds of coal according to 2:1:2:2:3 ratio, and the geometric optimization, annealing simulation and inverse verification are carried out. The aggregation model is established by using X-ray diffraction data and computer simulation techniques.we innovatively constructed five groups of macromolecular structure units of Taixi anthracite to characterize the results and simulate the minimum energy configuration of single chains and aggregate states. This research provides a molecular-level theoretical basis for the functionalization of Taixi anthracite.

Effects of molecule hydrophobicity and structural flexibility of appended bispecific antibody on Protein A chromatography

Appended bispecific antibody (aBsAb) with two single chain variable fragments (scFv) linked at the c-terminus of its heavy chains is one of the promising formats in bispecific therapeutics. The presence of hydrophobic and flexible scFv fragments render aBsAb molecules higher molecule hydrophobicity and structural flexibility compared to monoclonal antibody (mAb), thus making its purification more challenging. We set out to investigate how the unique molecular properties of aBsAb affect its performance on Protein A chromatography. We showed that aBsAb has a high propensity for chromatography-induced aggregation due to its high molecule hydrophobicity, and this couldn't be improved by the addition of common chaotropic salts. Moreover, the presence of chaotropic salts, such as arginine hydrochloride (Arg-HCl), retarded aBsAb elution during Protein A chromatography rather than facilitating which was widely observed in mAb Protein A elution. Nevertheless, we were able to overcome the aggregation issue by optimizing elution condition and improved aBsAb purity from 29 % to 93 % in Protein A eluate with a high molecular weight (HMW) species of less than 5 %. We also showed that the high molecular flexibility of aBsAb leads to different hydrodynamic sizes of the aBsAb molecule post Protein A elution, neutralization, and re-acidification, which are pH dependent. This is different from mAbs where their sizes do not change post neutralization even with re-exposure to acid. The above unique observations of aBsAb in Protein A chromatography were clearly explained from the perspectives of its high molecular hydrophobicity and structural flexibility.

FGF1

Fibroblast Growth Factor 1 (Fgf1), also known as acidic FGF (aFGF), is involved in the regulation of various biological processes, ranging from development to disease pathogenesis. It is a single chain polypeptide and is highly expressed in adult brain and kidney tissues. Its expression has been shown to be directed by multiple tissue-specific promoters, which generate transcripts of varying lengths. During development the Fgf1 gene is widely expressed, including in the neural tube, heart and lung. Mouse mutants for this gene are normal under standard laboratory conditions. However, when Fgf1 mutants are exposed to a high fat diet, an aggressive diabetic phenotype has been reported, along with aberrant adipose tissue expansion. Ongoing research on FGF1 and its signalling pathways holds promise for greater understanding of developmental processes as well as the development of novel therapeutic interventions for diseases including diabetes.

Reg2 treatment is protective but the induced Reg2 autoantibody is destructive to the islets in NOD mice

Regenerating family protein 2 (Reg2) is a trophic factor which stimulates β-cell replication and resists islet destruction. However, Reg2 also serves as an islet autoantigen, which makes it complicated to judge the effectiveness in treating diabetes. How Reg2 treatment behaves in non-obese diabetic (NOD) mice is to be investigated. NOD mice were treated with recombinant Reg2 protein, Complete Freund’s adjuvant (CFA) + PBS and CFA+Reg2 vaccinations, CFA+PBS- and CFA+Reg2-immunized antisera, and single chain variable fragment (scFv)-Reg2 and mIgG2a-Reg2 antibodies. Glycemic level, bodyweight, serum Reg2 antibody titer, glucose tolerance, and insulin secretion were determined. Islet morphological characteristics, insulitis, cell apoptosis, islet cell components, and T cell infiltration were analyzed by histological examinations. The autoantigenicity of constructed Reg2C and Reg2X fragments was determined in healthy BALB/c mice, and the bioactivity in stimulating cell proliferation and survival was assessed in insulinoma MIN6 cells. Reg2 administration alleviated diabetes in NOD mice with improved glucose tolerance and insulin secretion but elevated serum Reg2 autoantibodies. Histomorphometry showed reduced inflammatory area, TUNEL signal and CD8 + T cell infiltration, and increased β-cell proportion in support of the islet-protective effect of Reg2 treatment. CFA+PBS and CFA+Reg2 immunizations prevented diabetic onset and alleviated insulitis while injections of the antisera offered mild protections. Antibody treatments accelerated diabetic onset without increasing the overall incidence. Reg2C fragment depletes antigenicity, but reserves protective activity in streptozotocin (STZ)-treated MIN6 cells. In conclusion, Reg2 treatment alleviates type 1 diabetes (T1D) by preserving islet β-cells, but induces Reg2 autoantibody production which poses a potential risk of accelerating diabetic progression.

Screening and anti-angiogenesis activity of Chiloscyllium plagiosum anti-human VEGFR2 single-domain antibody.

Recently, the incidence of malignant tumors is on the rise and searching for new treatments on it has become the research priority. Blocking the vascular endothelial growth factor (VEGF) and its receptor (VEGFR) is one of the treatment strategies that used in the development of specific anti-angiogenic drugs. The deficiencies in tissue penetration and affinity maturation become the weakness of these drugs in anti-tumors applications. The single heavy chain antibody found in Chiloscyllium plagiosum, which has a low molecular weight and superior tissue penetration of variable region (variable new antigen receptor, VNARs), was considered to have the high antigen-binding activity and stability. This type of antibody has a simple structure that can be prokaryoticaly expressed, which makes it easily to produce new antiangiogenic target drugs. Specific anti-IgNAR rabbit multiple antibodies have been used to assess the level of VNARs in sharks and have shown a significant enrichment of IgNAR after triple immunization. An anti-VEGFR2 phage library was used for the targeted VNARs screening, and five candidate VNARs sequences were subsequently obtained by phage screening, followed by combined screening with the transcriptome library, and analysis of conserved regions along with 3D modelling matched the VNAR profile. ELISA and cell-based assays showed that two of the VNARs, VNAR-A6, and VNAR-E3, had a superior antigen affinity and anti-angiogenic activity thereby being able to inhibit human Umbilical Vein Endothelial Cells proliferation and migration. The anti-VEGFR2 VNARs derived from the immunized C. plagiosum and screened by phage library, which provide the new research ideas and specific approaches for the development of new drugs. The anti-VEGFR2 VNARs are capable for blocking the VEGF-VEGFR pathway, which of these may contribute to expanding the use of anti-angiogenic drugs.

New two-parameter constitutive models for rubber-like materials: Revisiting the relationship between single chain stretch and continuum deformation

The connection between macroscopic deformation and microscopic chain stretch is a key element in constitutive models for rubber-like materials that are based on the statistical mechanics of polymer chains. A new micro-macro chain stretch relation is proposed, using the Irving–Kirkwood–Noll procedure to construct a Cauchy stress tensor from forces along polymer chains. This construction assumes that the deformed polymer network remains approximately isotropic for low to moderate macroscopic stretches, a starting point recently adopted in the literature to propose a non-affine micro-macro chain stretch relation (Amores et al., 2021). Requiring the constructed Cauchy stress to be consistent with the stress tensor derived from the strain energy density results in a new chain stretch relation involving the exponential function. A hybrid chain stretch relation combining the new chain stretch with the well-known affine relation is then proposed to account for the whole range of stretches in experimental datasets. Comparison of the model predictions to experimental data in the literature shows that the two new micro-macro chain stretch relations in this work result in two-parameter constitutive models that outperform those based on existing chain stretches with no increase in the number of fitting parameters used.

Stretching multistate flexible chains and loops.

Polymer loop structure commonly appears in biological phenomena, such as DNA looping and DNA denaturation. When a chain forms a loop, its elastic behavior differs from that of an open chain due to the loss of entropy. In the case of reversible loop formation, interesting behavior emerges related to the multistate nature of the conformations. In this study, we model a multistate reversible loop as a looping Gaussian chain, which can bind (close) reversibly at one or several points to form a loop, or a zipping Gaussian loop, which can zip reversibly to form a double-stranded chain. For each model, we calculate the force-extension relations in the fixed-extension (Helmholtz) and the fixed-force (Gibbs) statistical ensembles. Unlike the single Gaussian chain or loop, the multilevel systems demonstrate qualitatively distinct tensile elasticity and ensemble inequivalence. In addition, we investigate a Gaussian necklace consisting of reversible alternating blocks of the zipped chain and loop and obtain the force-temperature phase diagram. The phase diagram implies a force-induced phase transition from a completely looped (denatured) state to a mixed (bound) state.

Anchor chains—A simple low‐cost device to assist passage of small‐bodied mass fish

AbstractAttention has been placed on a variety of barriers that hinder fish passage in modern times. The most prevalent fish barriers were culverts which have negatively impacted waterway connectivity and fish habitats. For small‐bodied mass fish, high barrel velocities and turbulence have reduced fish swimming performance because of their weak swimming capabilities. In the present study, physical testing was conducted under controlled flow conditions to assess the extent and magnitude of turbulence characteristics, secondary flow and low‐velocity zones in a 0.5‐m‐wide box culvert barrel. Two cases were investigated; a reference case consisting of a smooth rectangular channel and a low‐cost design solution to improve upstream fish migration consisting of a single galvanized anchor chain fitted within a smooth rectangular channel. The single anchor chain was positioned towards one corner of the channel to induce asymmetric flow, reducing overall energy losses and enhancing the existing low‐velocity zone in the adjacent channel corner. The anchor chain induced a strong turbulent flow motion away from the anchor chain, characterized by higher Reynolds stress and turbulent kinetic energy, along with a distinct channel flow asymmetry. Conversely, the low‐velocity zone, between the anchor chain and the bottom channel corner, was significantly expanded with reduced longitudinal mean velocities and turbulent scales. Whilst the anchor chain link contributed to some complex localized wake flow, the anchor chain also influenced the distributions of normal turbulent stresses (v'z2 – v'y2), which in turn influenced the location of secondary flow cells. This secondary flow redirected low momentum fluid into the low‐velocity zones, setting the conditions for the favorable upstream passage of small‐bodied mass fish species.

Cancer Antibody Engineering: Comparison of Mammalian, Yeast, Bacterial, Plants, Cell-free and Hybridoma Expression Systems.

Cancer is a significant issue worldwide. Generally, commercially available treatments, such as surgery, radiotherapy, and chemotherapy, are associated with undesirable complications. Hence, immunotherapy serves as a crucial alternative to those treatment options. This modality is aimed to boost the immune system through the application of engineered antibodies, which can be produced using recombinant DNA technology. The discussion of the technologies leads to an introduction of the single-chain variable fragment (scFv). Thereafter, the advantages, disadvantages, and challenges associated with different expression systems, such as mammalian cells, yeast cells, bacterial cells, plant cells, and phage display were discussed comprehensively. Furthermore, conventional approaches such as hybridoma and modern approaches such as cell-free protein synthesis (CFPS) and simple colony assays are included. In short, this article has compiled evidence relating to each display system and may serve as a reference for those who aim to explore antibody engineering using one of the methods listed in this article.

Wiring Covalent Organic Frameworks with Conducting Polymers.

Covalent organic frameworks are a class of crystalline porous polymers formed by linking organic units into periodically aligned skeletons and pores. Here we report a strategy for wiring these frameworks with conducting polymers via wall engineering and polymerization. We anchored each edge site with one pyrrole unit, which is densely packed along the z direction yet protruded from pore walls. This assembly enables the polymerization of pyrrole units to form polypyrrole and creates a new polypyrrole chain conformation. The resultant framework constitutes six single file polypyrrole chains in each pore and develop spatially segregated yet built-in single molecular wires with exceptional stable polarons. Hall effect measurements revealed that the materials are p-type semiconductors, increase conductivity by eight orders of magnitude compared to the pristine frameworks, and achieve a carrier mobility as large as 13.2 cm2 V-1 s-1. Our results open an avenue to π electronic frameworks by interlayer molecular wiring with conducting polymers.

Anti-hemagglutinin monomeric nanobody provides prophylactic immunity against H1 subtype influenza A viruses.

Influenza viruses constitute a major threat to human health globally. The viral surface glycoprotein hemagglutinin (HA) is the immunodominant antigen, contains the site for binding to the cellular receptor (RBS), and it is the major target of neutralizing antibody responses post-infection. We developed llama-derived single chain antibody fragments (VHHs) specific for type A influenza virus. Four VHHs were identified and further characterized. VHH D81 bound residues in the proximity of the C-terminal region of HA1 of H1 and H5 subtypes, and showed weak neutralizing activity, whereas VHH B33 bound residues in the proximity of the N-terminal region of the HA's stem domain (HA2) of H1, H5, and H9 subtypes, and showed no neutralizing activity. Of most relevance, VHHs E13 and G41 recognized highly conserved conformational epitopes on the H1 HA's globular domain (HA1) and showed high virus neutralizing activity (ranging between 0.94 to 0.01μM), when tested against several human H1N1 isolates. Additionally, E13 displayed abrogated virus replication of a panel of H1N1 strains spanning over 80 years of antigenic drift and isolated from human, avian, and swine origin. Interestingly, E13 conferred protection in vivo at a dose as low as 0.05 mg/kg. Mice treated with E13 intranasally resulted in undetectable virus challenge loads in the lungs at day 4 post-challenge. The transfer of sterilizing pan-H1 immunity, by a dose in the range of micrograms given intranasally, is of major significance for a monomeric VHH and supports the further development of E13 as an immunotherapeutic agent for the mitigation of influenza infections.

Dynamic Behavior of Poly(N-isopropylmethacrylamide) in Neat Water and in Water/Methanol Mixtures.

We investigate the collective dynamics of thermoresponsive polymer poly(N-isopropylmethacrylamide) (PNIPMAM) in aqueous solution and in water/methanol mixtures in the one-phase region. In neat water, the polymer concentration c is varied in a wide range around the overlap concentration c*, that is estimated at 23 g L-1. Using dynamic light scattering (DLS), two decays ("modes") are consistently observed in the intensity autocorrelation functions for c = 2-150 g L-1 with relaxation rates which are proportional to the square of the momentum transfer. Below c*, these are attributed to the diffusion of single chains and to clusters from PNIPMAM that are formed due to hydrophobic interactions. Above c*, they are assigned to the diffusion of the chain segments between overlap points and to long-range concentration fluctuations. From the temperature-dependent behavior of the overall scattering intensities and the dynamic correlation lengths of the fast mode, the critical temperatures and the scaling exponents are determined. The latter are significantly lower than the static values predicted by mean-field theory, which may be related to the presence of the large-scale inhomogeneities. The effect of the cosolvent methanol on the dynamics is investigated for polymer solutions having c = 30 g L-1 and methanol volume fractions in the solvent mixtures of up to 60 vol %. The phase diagram was established by differential scanning calorimetry. The slow mode detected by DLS becomes significantly weaker as methanol is added, i.e., the solutions become more homogeneous. Beyond the minimum of the coexistence line, which is located at 40-50 vol % of methanol, the dynamics is qualitatively different from the one at lower methanol contents. Thus, going from the water-rich to the methanol-rich side of the miscibility gap, the change of interaction of the PNIPMAM chains with the two solvents has a severe effect on the collective dynamics.