bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the welfare effects of recombinant bovine somatotropin from 1996 to 2002 in the USA
Authors: LOSINGER WILLARD C
Published: July 2007

From 1996 to 2002, the percentage of dairy cows treated with recombinant bovine somatotopin (rBST) in the USA more than doubled, while the price of milk fell considerably. The benefits of the increased milk production to consumers, and to the economy as a whole, were greater in 2002 than in 1996. The economic surplus of producers who did not use rBST was more negatively affected by rBST in 2002 than in 1996. Dairy producers who used rBST enjoyed an increased economic surplus from the increased milk production associated with rBST during 1996. During 2002, the impact on producer surplus for users of rBST was not significantly different from zero.
Construction and Characterization of Shuttle Vectors for Succinic Acid-Producing Rumen Bacteria
Authors: Jang Yu-Sin , Jung Young Ryul , Lee Sang Yup , Kim Ji Mahn , Lee Jeong Wook , Oh Doo-Byoung , Kang Hyun Ah , Kwon Ohsuk , Jang Seh Hee , Song Hyohak , Lee Sang Jun , Kang Kyu Young
Published: July 2007

Shuttle vectors carrying the origins of replication that function in
Escherichia coli
and two capnophilic rumen bacteria,
Mannheimia succiniciproducens
and
Actinobacillus succinogenes
, were constructed. These vectors were found to be present at ca. 10 copies per cell. They were found to be stably maintained in rumen bacteria during the serial subcultures in the absence of antibiotic pressure for 216 generations. By optimizing the electroporation condition, the transformation efficiencies of 3.0 × 10
6
and 7.1 × 10
6
transformants/μg DNA were obtained with
M. succiniciproducens
and
A. succinogenes
, respectively. A 1.7-kb minimal replicon was identified that consists of the
rep
gene, four iterons, A+T-rich regions, and a
dnaA
box. It was found that the shuttle vector replicates via the theta mode, which was confirmed by sequence analysis and Southern hybridization. These shuttle vectors were found to be suitable as expression vectors as the homologous
fumC
gene encoding fumarase and the heterologous genes encoding green fluorescence protein and red fluorescence protein could be expressed successfully. Thus, the shuttle vectors developed in this study should be useful for genetic and metabolic engineering of succinic acid-producing rumen bacteria.
Artificial Control of Nitrate Respiration through the
lac
Promoter Permits the Assessment of Oxygen-Mediated Posttranslational Regulation of the
nar
Operon in
Pseudomonas aeruginosa
Authors: Noriega Chris E. , Sharma Vandana , Rowe John J.
Published: July 2007

In this study, oxygen and nitrate regulation of transcription and subsequent protein expression of the unique
narK1K2GHJI
respiratory operon of
Pseudomonas aeruginosa
were investigated. Under the control of P
LAC
,
P. aeruginosa
was able to transcribe
nar
and subsequently express methyl viologen-linked nitrate reductase activity under aerobic conditions without nitrate. Modulation of P
LAC
through the LacI repressor enabled us to assess both transcriptional and posttranslational regulation by oxygen during physiological whole-cell nitrate reduction.
The Serine Protease HhoA from
Synechocystis
sp. Strain PCC 6803: Substrate Specificity and Formation of a Hexameric Complex Are Regulated by the PDZ Domain
Authors: Huesgen Pitter F. , Scholz Philipp , Adamska Iwona
Published: July 2007

Enzymes of the ATP-independent Deg serine endopeptidase family are very flexible with regard to their substrate specificity. Some family members cleave only one substrate, while others act as general proteases on unfolded substrates. The proteolytic activity of Deg proteases is regulated by PDZ protein interaction domains. Here we characterized the HhoA protease from
Synechocystis
sp. strain PCC 6803 in vitro using several recombinant protein constructs. The proteolytic activity of HhoA was found to increase with temperature and basic pH and was stimulated by the addition of Mg
2+
or Ca
2+
. We found that the single PDZ domain of HhoA played a critical role in regulating protease activity and in the assembly of a hexameric complex. Deletion of the PDZ domain strongly reduced proteolysis of a sterically challenging resorufin-labeled casein substrate, but unlabeled β-casein was still degraded. Reconstitution of the purified HhoA with total membrane proteins isolated from
Synechocystis
sp. wild-type strain PCC 6803 and a Δ
hhoA
mutant resulted in specific degradation of selected proteins at elevated temperatures. We concluded that a single PDZ domain of HhoA plays a critical role in defining the protease activity and oligomerization state, combining the functions that are attributed to two PDZ domains in the homologous DegP protease from
Escherichia coli
. Based on this first enzymatic study of a Deg protease from cyanobacteria, we propose a general role for HhoA in the quality control of extracytoplasmic proteins, including membrane proteins, in
Synechocystis
sp. strain PCC 6803.
Contact: Tact and Caress
Authors: Lingis Alphonso
Published: July 2007

Through words and gestures we communicate with one another about the outlying environment, and we also form representations of one another. But we also make contact with one another. Through tact we make contact with the anxieties, rage, shame, shyness, and secrecy of another. In caresses we make contact with the pleasure of the other. Our caresses are moved by the other, by the spasms of torment and pleasure in the other.
The Usefulness of Unit Weights in Creating Composite Scores
Authors: Bobko Philip , Roth Philip L. , Buster Maury A.
Published: July 2007

Combining/weighting subscores into an aggregate score involves issues that apply to many fields in the organizational sciences (e.g., weighting predictors in selection, weighting multiple performance appraisal indicators, overall evaluation of organizations). The weights that are used in practice can be different (differential weights) or equal (unit weights). Relevant literature across multiple disciplines and multiple decades is reviewed. The literature indicates that unit weights have substantial predictive validity when compared with regression weights, but there is a lack of data on how other differential weighting strategies (e.g., weights generated by subject matter experts) compare to unit weights. In response, a primary and a meta-analytic study are provided here. The recent literature also contains some potential criticisms of unit weights in regard to personnel selection and content validation—and those statements are evaluated. The data and findings indicate that unit weights can be a highly appropriate approach for weighting under many circumstances.
Inference of transcription modification in long-live yeast strains from their expression profiles
Authors: Cheng Chao , Fabrizio Paola , Ge Huanying , Longo Valter D , Li Lei M
Published: July 2007

Background

Three kinases: Sch9, PKA and TOR, are suggested to be involved in both the replicative and chronological ageing in yeast. They function in pathways whose down-regulation leads to life span extension. Several stress response proteins, including two transcription factors Msn2 and Msn4, mediate the longevity extension phenotype associated with decreased activity of either Sch9, PKA, or TOR. However, the mechanisms of longevity, especially the underlying transcription program have not been fully understood.

Results

We measured the gene expression profiles in wild type yeast and three long-lived mutants: sch9 Δ, ras2 Δ, and tor1 Δ. To elucidate the transcription program that may account for the longevity extension, we identified the transcription factors that are systematically and significantly associated with the expression differentiation in these mutants with respect to wild type by integrating microarray expression data with motif and ChIP-chip data, respectively. Our analysis suggests that three stress response transcription factors, Msn2, Msn4 and Gis1, are activated in all the three mutants. We also identify some other transcription factors such as Fhl1 and Hsf1, which may also be involved in the transcriptional modification in the long-lived mutants.

Conclusion

Combining microarray expression data with other data sources such as motif and ChIP-chip data provides biological insights into the transcription modification that leads to life span extension. In the chronologically long-lived mutant: sch9 Δ, ras2 Δ, and tor1 Δ, several common stress response transcription factors are activated compared with the wild type according to our systematic transcription inference.
Transferrin-conjugated solid lipid nanoparticles for enhanced delivery of quinine dihydrochloride to the brain
Authors: Gupta Yashwant , Jain Anekant , Jain Sanjay K
Published: July 2007

Transferrin (Tf)-conjugated solid lipid nanoparticles (SLNs) were investigated for their ability to deliver quinine dihydrochloride to the brain, for the management of cerebral malaria. SLNs were prepared by an ethanol injection method using hydrogenated soya phosphatidyl choline (HSPC), triolein, cholesterol and distearylphosphatidylethanolamine (DSPE). Coupling of SLNs with Tf was achieved by incubation of Tf with quinine-loaded SLNs in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) hydrochloride in phosphate buffered saline (pH 7.4) as a cross-linker. SLNs were characterized for shape, particle size, polydispersity and percentage drug entrapment. The SLNs were 108–126 nm in size, and maximum drug entrapment was 38.4–42.7%. Average size increased on coupling with Tf but percentage drug entrapment was reduced. The in-vitro release profile was determined using a dialysis technique; non-conjugated SLNs released comparatively more drug than Tf-SLNs. Fluorescence studies revealed enhanced uptake of Tf-SLNs in brain tissue compared with unconjugated SLNs. In in-vivo performance studies, quinine plasma level and tissue distribution after intravenous administration of drug-loaded Tf-SLNs and unconjugated SLNs was compared with that of free drug. Intravenous administration of quinine dihydrochloride solution resulted in much higher concentrations of drug in the serum than with SLNs. Conjugation of SLNs with Tf significantly enhanced the brain uptake of quinine which was shown by the recovery of a higher percentage of the dose from the brain following administration of Tf-coupled SLNs compared with unconjugated SLNs or drug solution.
Pharmacokinetics of DA-7218, a new oxazolidinone, and its active metabolite, DA-7157, after intravenous and oral administration of DA-7218 and DA-7157 to rats
Authors: Bae Soo K , Yang Si H , Shin Karen N , Rhee Jae K , Yoo Moohi , Lee Myung G
Published: July 2007

DA-7218 (a prodrug of DA-7157), a new oxazolidinone, was hydrolysed via phosphatase to form its active metabolite, DA-7157, in rats. The pharmacokinetic parameters of DA-7218 and DA-7157 were evaluated after intravenous (5, 10 and 20 mg kg−1) and oral (20, 50 and 100 mg kg−1) administration of DA-7218 to rats. DA-7218 and DA-7157 exhibited dose-proportional pharmacokinetics after both intravenous and oral administration of DA-7218 to rats. The stability of DA-7218 and DA-7157, blood partition of DA-7157, and the plasma protein binding of DA-7157 were also evaluated. DA-7218 was unstable in rat blood, plasma, bile and liver homogenates, but DA-7157 was stable, suggesting that DA-7218 is hydrolysed via phosphatase. DA-7157 rapidly reached equilibrium between plasma and blood cells, and the mean equilibrium plasma-to-blood cells ratio was 3.18, indicating that binding of DA-7157 to blood cells was not considerable. The protein binding of DA-7157 in fresh rat plasma was 93.4%.
CJY, an isoflavone, reverses P-glycoprotein-mediated multidrug-resistance in doxorubicin-resistant human myelogenous leukaemia (K562/DOX) cells
Authors: Ji Bian-Sheng , He Ling
Published: July 2007

In an effort to develop safe and effective multidrug-resistance (MDR) reversing agents, the effect of CJY, an isoflavone, on the P-glycoprotein (P-gp) function and P-gp-mediated MDR was evaluated in doxorubicin-resistant human myelogenous leukaemia (K562/DOX) cells. The results showed that CJY caused a marked increase in accumulation and a notable decrease in efflux of rhodamine 123 (Rh123). The inhibitory effect of the agent on P-gp function persisted for at least 120 min after removal of 2.5 μM CJY from the incubation medium. The doxorubicin-induced cytotoxicity, apoptosis and cell cycle perturbations were significantly potentiated by CJY. The intracellular accumulation of doxorubicin was also enhanced. The compound exhibited potent effects in-vitro on the reversal of P-gp-mediated MDR, suggesting that it could become a candidate as an effective MDR reversing agent in cancer chemotherapy.
Stress intensity factor solutions for kinked surface cracks
Authors: Yingzhi Li , Hills D A
Published: July 2007

A general method is described of determining the stress intensity factors for two-dimensional cracks composed of straight segments but with one or more angular discontinuities. The bulk stress field used is for illustrative purposes only, and the only requirement is that the crack remains open throughout its length.
Membrane action in the beam mechanism
Authors: Ronalds B F
Published: July 2007

Bending moment and axial force interaction formulae are derived for a fully plastic section comprising up to three plate segments. They are utilized in a plastic mechanism analysis of a point-loaded beam with partial axial restraint. The destabilizing effect of a pre-compression stress is noted. The range of validity of the analysis is limited by material tearing at large strains, and so the manner in which the strain increases with lateral deflection, and its dependence on the beam geometry and the precise length over which the load is applied, are studied. Tests and finite element solutions are described, which show good agreement with the mechanism approach.
Quantitative stress analysis based on the measured trace of the stress tensor
Authors: Huang Y M , Rowlands R E
Published: July 2007

An effective method is developed for determining the individual stresses from the trace of the stress tensor (isopachics) in a region adjacent to an arbitrarily-shaped traction-free boundary of a loaded component. The approach is facilitated by the fact that the stresses throughout such a region can be described completely in terms of only one complex potential. Equilibrium and compatibility prevail within the region, and the traction-free boundary conditions are satisfied. The concept is expected to be particularly useful for thermoelastic stress analysis.
Elastic load-displacement predictions for coned disc springs subjected to axial loading using the finite element method
Authors: Bagavathiperumal P , Chandrasekaran K , Manivasagam S
Published: July 2007

The elastic load-displacement analysis of coned disc springs using the finite element method (FEM) is presented. The analysis considers the geometrical non-linearity of such springs within the working range using 8-noded isoparametric elements. The springs are analysed for a uniformly distributed axial load around the upper inner boundary with the lower outer boundary constrained vertically and other edges kept free. Verification of the present technique is obtained by analysing reference problems. Good correlation between the computed results and referenced data can be drawn.
The design of joints between elastically dissimilar components (with special reference to ceramic/metal joints)
Authors: Kelly P A , Hills D A , Nowell D
Published: July 2007

Three kinds of joints between bonded, elastically dissimilar components loaded in tension are studied. Each involves a plane interface, but with various changes in geometry at the outside edge of the bond. These geometric features are intended to avoid singularities which would otherwise arise there, and should therefore inhibit peeling of the joint and hence the formation of a crack. Explicit equations describing the necessary conditions in terms of the elastic parameters of the bonded components are given.
An improved method for determining free boundary stresses
Authors: Soh A K
Published: July 2007

The conventional finite element method shows its weakness in determining the stress distributions along free boundaries. This is because the chosen element displacement functions do not implicitly satisfy the conditions which prevail at the free boundaries. A procedure has been proposed to modify the conventional finite element method so as to allow the elastic stresses along the free boundaries of two- and three-dimensional structures to be determined with improved accuracy. The results obtained by this modified method for a two-dimensional problem are compared with both a photoelastic and a traditional finite element solution. The comparison shows that the modified solution is in better agreement with the photoelastic test data as compared with the traditional solution. The results obtained by the modified method for a three-dimensional problem is compared with a traditional finite element solution and the former is found to be superior.
A multiaxial stress-strain analysis for proportional cyclic loading
Authors: Navarro A , Brown M W , Miller K J
Published: July 2007

A simplified treatment is presented for the analysis of tubular specimens subject to in-phase tension-torsion loads in the elasto-plastic regime. Use is made of a hardening function readily obtainable from the uniaxial cyclic stress-strain curve and hysteresis loops. Expressions are given for incremental as well as deformation theories of plasticity. The reversals of loading are modelled by referring the flow equations to the point of reversal and calculating distances from the point of reversal using a yield critertion. The method has been used to predict the deformation response of in-phase tests on an En15R steel, and comparisons with experimental data are provided. The material exhibited a non-Masing type behaviour. A power law rule is developed for predicting multiaxial cyclic response from uniaxial data by incorporating a hysteretic strain hardening exponent.
A review of the determination of energy release rates for strips in tension and bending. Part I – static solutions
Authors: Williams J G
Published: July 2007

It is shown that solutions for the energy release rate G may be obtained for a uniform strip by simply considering the change in length. The simplicity of the system enables a wide range of boundary conditions and material properties to be incorporated into the analysis and G may be computed for elastic and elastic-plastic materials. Inextensible flexible strips are considered first as they are useful for modelling peel tests and these results are developed to cover elastic and elastic-plastic behaviour. Elastic strips in tension are also considered and the analysis is developed to include transverse loading which induces bending. General considerations of path and loading history dependence are also included.
Fracture mechanics in the creep range
Authors: Webster G A
Published: July 2007

Cracked high temperature components may fail by crack growth, net-section rupture, or some combination of both processes. This paper reviews the fracture mechanics concepts required to describe this behaviour. Procedures are presented for evaluating relevant characterizing parameters using experimental, numerical and limit analysis methods. Models for predicting crack propagation rates from uni-axial creep data involving ductility exhaustion in a process zone at a crack tip are outlined. Both the influence of build-up of damage in the process zone and material deterioration in the uncracked ligament are considered. It is shown that the models give satisfactory correlations with experimental data.
The use of continuum damage mechanics in creep analysis for design
Authors: Hayhurst D R
Published: July 2007

The common theme of this paper is the use of Creep Continuum Damage Mechanics (CDM) in design analysis. It is shown how this approach has the capability to model the deformation and rupture behaviour of components which includes simple ligament situations, notched components, cracked members, and butt-welded steam pipes. The following three principal materials requirments are highlighted: (I) deformation behaviour including damage synergisms; (II) damage kinetics and their relation to physical mechanisms; and (III) stress state, stress level, and temperature dependence of the deformation, damage, and material failure. New methods are discussed for the determination of multi-axial stress rupture criteria. The use of CDM with mechanisms-based constitutive equations to analyse component behaviour in design is design is demonstrated.
Evaluation of fracture mechanic's parameters using electronic speckle pattern interferometry
Authors: Moore A J , Tyrer J R
Published: July 2007

Electronic speckle pattern interferometry has been used to calculate KI and J for compact tension specimens. Automated fringe pattern analysis enables the full field of data to be used with the minimum of operator intervention. Measurements are shown to be accurate to within 10 per cent. The J-measurement procedure employed could form the basis of an automatic fault detection system.
Photoelastic investigation of stress intensifications in the interacting nozzle attachment region of pressure vessels
Authors: Mulchandani K B , Shukla D P
Published: July 2007

In this paper, the problem of determining the opening mode (mode I) stress intensity factor (SIF) from the photoelastic isochromatic fringe pattern associated with a surface crack located in the ligament region between two radial nozzle-cylinder junctions of pressure vessel has been investigated. The objective is to determine the influence of geometry, size and location of the surface flaw with respect to the radial nozzles. Starting from the crack tip stress field formulation of Etheridge and Dally using three parameters (1)† a new method suited to the analysis of photoelastic data obtained from a single isochromatic fringe loop to extract the SIF has been introduced. This new method has been used to predict SIFs for a range of pressure vessel nozzle spacings when photoelastic models are subjected to internal pressure loading.
Modelling an orthopaedic knee prosthesis as a layered elastic system part 1: Experimental and theoretical analyses
Authors: Whelan M P , O'Donnell P , Little E G
Published: July 2007

The purpose of this investigation was to produce a simplified model of the plastic tibial plateau of a typical unicondylar knee prosthesis that would allow the parametric study of contact stresses experienced by the plastic component during relatively severe loading conditions. This involved the design, production and testing of a three-dimensional axisymmetric embedded strain gauge model of the tibial plateau and the application of a suitable theoretical analysis. The principal feature of the strain gauge model was the possibility of varying the thickness during the experimental procedure while keeping the maximum number of embedded gauges active. The Hertzian contact theory was used as a basis for the prediction of integration errors associated with placing strain gauges in locations subject to large strain gradients. A theoretical analysis that took the layered nature of the contact model into account was carried out which provided full field data for comparison with Hertzian and experimental results. Good agreement was obtained between theoretical and experimental values along the model axis, while at off-axis locations theoretical results based on the layered analysis compared reasonably with embedded strain gauge data. Very slight discrepancies between the experimental and idealized boundary conditions present in the initial stages of testing resulted in significant differences between embedded strain gauge and theoretical data.
Stress concentration due to shallow spherical surface hollows on a slab
Authors: Wang J-H
Published: July 2007

A hollow on the surface of a slab is a common defect. This paper presents the results of a three-dimensional photoelastic experiment to show stress concentration due to a single shallow spherical hollow in a free surface of a slab and the increases of the stress concentration due to the presence of double hollows.
Characteristics of fibre-core wire rope
Authors: Raoof M , Kraincanic I
Published: July 2007

The theoretical analysis of a large-diameter stranded wire rope with fibre core, using results from a previously reported orthotropic sheet model for analysing the behaviour of its constituent helical strands, is reported. The present model is (unlike previously available theories for stranded wire ropes) capable of catering for the effects of interwire friction and contact deformations.

The proposed theory provides a fairly simple means of obtaining the upper (no-slip) and lower (full-slip) bounds to rope effective stiffness coefficients under axial/torsional coupling with encouraging correlations found between the theoretical predictions for the axial stiffness under full-slip conditions and experimental data for some realistic stranded wire ropes with fibre cores.
The stress concentration of an open complete rotating ring
Authors: Batista M , Kosel F
Published: July 2007

In this paper two methods used to satisfy the boundary conditions in the case of an open complete rotating ring are considered. It turns out that for smaller ratios of radii the collocation method yields better results than the moment method.
Tensile flow and instability in galvanized, rolled steel sheet
Authors: Rees D W A
Published: July 2007

This paper examines flow and instability of a zinc-clad sheet used for the manufacture of car panels. Three forming properties are reported from off-axis tensile testing: (a) anisotropy in the plane of the sheet, (b) tensile instability and (c) homogeneity of deformation. The analysis correlates the directional flow behaviour using the Hill yield function (1)† as a basis for equivalence. This function explains satisfactorily the linear plastic strain paths and the variation in r values observed but does contract flow behaviour to a single curve. A subtangent is derived for the off-axis testpiece in terms of its orientation and two strain ratios referred to its axis. This is used to derive the limiting uniform strain that is found to remain constant in regions exterior to local neck formation. A condition is established for which the principal axes of stress and plastic strain remain coincident. It is shown, from the measured rotations of the principal material axes, that deformations conform to standard strain transformation equations upon removal of rigid-body rotations.
Three-dimensional finite element analysis and strength evaluation of link chains in chain hoists subjected to impact loads
Authors: Hiroshima T , Sawa T
Published: July 2007

Elastoplastic stresses in link chains subjected to impact loads are analysed using a finite element method. The code employed is ‘DYNA3D’. Chain strength is predicted by using the von Mises criterion. The effects of chain dimensions on the stress distribution, a location where rupture occurs, and on the chain strength are examined. Measurement of the strains in link chain and impact tensile tests were also performed when impact loads were applied to a link. Fairly good agreement is seen between the numerical and the experimental results. It was found that chain strength can be predicted by using the relationship between chain elongation and impact energy. The chain strength can be improved by optimizing the chain geometry (pitch, width and compressed depth) using finite element analysis.
Creep deformation and rupture of low alloy ferritic weldments under shear loading
Authors: Kimmins S T , Walker N S , Smith D J
Published: July 2007

A novel testing technique has been employed to study the creep properties of ferritic steel weldments under shear loading. The technique allows examination of microstructurally distinct regions, such as the type IV region of the heat-affected zone, in relative isolation from adjacent material. When results from the shear tests are compared with uniaxial data an appropriate stress for determining creep rupture under multi-axial loading may be deduced. The stress rupture behaviour of shear and uniaxial tests as a function of stress and temperature are consistent. It is suggested that this test technique deserves wider application for the examination of the creep properties of materials that are microstructurally inhomogeneous.
Optimization of depth increment distribution in the ring-core method
Authors: Zuccarello B
Published: July 2007

The integral equation method is the most suitable calculation procedure for the determination of non-uniform residual stresses by semi-destructive mechanical methods such as hole and ring-core drilling. However, the high sensitivity to strain measurement errors due to the ill-conditioning of the equation sets has prevented its practical use. Examination of the influence of the strain measurement error on the calculated stresses and its propagation has shown that, for given maximum groove depth and total steps number, the error sensitivity depends on the particular depth increment distribution used. By means of an alternative matrix formulation of the equation sets the depth increment distribution that optimizes the numerical conditioning has been investigated. Numerical simulations carried out by means of the boundary element method as well as an experimental test have corroborated the best performance of the depth increment distribution proposed in comparison with the constant and increasing depth increment distributions commonly used.
Stress intensity factors for cracks emanating from a semicircular notch in a half-plate
Authors: Lin S , Hills D A
Published: July 2007

Two methods are developed for determining the stress intensity factors arising at the tip of a crack growing from a semicircular surface notch. The dislocation density method and boundary element formulations are employed, and the technique developed may be readily extended to notches of different forms, and arbitrarily positioned or shaped cracks, while retaining numerical efficiency.
A more efficient RNAi inducible system for tight regulation of gene expression in mammalian cells and xenograft animals
Authors: Zhang Jing , Wang Cuiying , Ke Ning , Bliesath Josh , Chionis John , He Qiuchen S. , Li Qi-xiang , Chatterton Jon E. , Wong-Staal Flossie , Zhou Demin
Published: July 2007

Two types of tetracycline-controlled inducible RNAi expression systems have been developed that generally utilize multiple tetracycline operators (TetOs) or repressor fusion proteins to overcome the siRNA leakiness. Here, we report a novel system that overexpresses the tetracycline repressor (TetR) via a bicistronic construct to control siRNA expression. The high level of TetR expression ensures that the inducible promoter is tightly bound, with minimal basal transcription, allowing for regulation solely dependent on TetR rather than a TetR fusion protein via a more complicated mechanism. At the same time, this system contains only a single TetO, thus minimizing the promoter impairment occurring in existing systems due to the incorporation of multiple TetOs, and maximizing the siRNA expression upon induction. In addition, this system combines all the components required for regulation of siRNA expression into a single lentiviral vector, so that stable cell lines can be generated by a single transduction and selection, with significant reduction in time and cost. Taken together, this all-in-one lentiviral vector with the feature of TetR overexpression provides a unique and more efficient tool for conditional gene knockdown that has wide applications. We have demonstrated the high degree of robustness and versatility of this system as applied to several mammalian cells and xenograft animals.
A Graphene Composite Film Based Wearable Far‐Infrared Therapy Apparatus (GRAFT) for Effective Prevention of Postoperative Peritoneal Adhesion
Authors: Lu Xiaohuan , Xu Luming , Song Yu , Yu Xiangnan , Li Qilin , Liu Feng , Li Xiaoqiong , Xi Jiangbo , Wang Shuai , Wang Lin , Wang Zheng
Published: March 2024

Postoperative peritoneal adhesion (PPA) is the most frequent complication after abdominal surgery. Current anti‐adhesion strategies largely rely on the use of physical separating barriers creating an interface blocking peritoneal adhesion, which cannot reduce inflammation and suffers from limited anti‐adhesion efficacy with unwanted side effects. Here, by exploiting the alternative activated macrophages to alleviate inflammation in adhesion development, a flexible graphene‐composite‐film (F‐GCF) generating far‐infrared (FIR) irradiation that effectively modulates the macrophage phenotype toward the anti‐inflammatory M2 type, resulting in reduced PPA formation, is designed. The anti‐adhesion effect of the FIR generated by F‐GCF is determined in the rat abdominal wall abrasion‐cecum defect models, which exhibit reduced incidence and area of PPA by 67.0% and 92.1% after FIR treatment without skin damage, significantly superior to the clinically used chitosan hydrogel. Notably, within peritoneal macrophages, FIR reduces inflammation reaction and promotes tissue plasminogen activator (t‐PA) level via the polarization of peritoneal macrophages through upregulating Nr4a2 expression. To facilitate clinical use, a wirelessly controlled, wearable, F‐GCF‐based FIR therapy apparatus (GRAFT) is further developed and its remarkable anti‐adhesion ability in the porcine PPA model is revealed. Collectively, the physical, biochemical, and in vivo preclinical data provide compelling evidence demonstrating the clinical‐translational value of FIR in PPA prevention.
Label‐Free Virtual Peritoneal Lavage Cytology via Deep‐Learning‐Assisted Single‐Color Stimulated Raman Scattering Microscopy
Authors: Fang Tinghe , Wu Zhouqiao , Chen Xun , Tan Luxin , Li Zhongwu , Ji Jiafu , Fan Yubo , Li Ziyu , Yue Shuhua
Published: March 2024

Clinical guidelines for gastric cancer treatment recommend intraoperative peritoneal lavage cytology to detect free cancer cells. Patients with positive cytology require neoadjuvant chemotherapy instead of instant resection, and conversion to negative cytology results in improved survival. However, pathologists’ or artificial intelligence's accuracy of cytological diagnosis is disturbed by manually produced, unstandardized slides. In addition, the elaborate infrastructure makes cytology accessible to a limited number of medical institutes. This work develops CellGAN, a deep learning method that enables label‐free virtual peritoneal lavage cytology by producing virtual hematoxylin–eosin‐stained images with single‐color stimulated Raman scattering microscopy. A structural similarity loss is introduced to overcome the challenge of unsupervised virtual pathology techniques that cannot accurately present cellular structures. This method achieves a structural similarity of 0.820 ± 0.041 and a nucleus area consistency of 0.698 ± 0.102, indicating the staining fidelity outperforms the state‐of‐the‐art method. Diagnosis using virtually stained cells reaches 93.8% accuracy and substantial consistency with conventional staining. Single‐cell detection and classification on virtual slides achieve a mean average precision of 0.924 and an area under the receiver operating characteristic curve of 0.906, respectively. Collectively, this method achieves standardized and accurate virtual peritoneal lavage cytology and holds great potential for clinical translation.
Efficient electromagnetic interference shielding performance of poly(amide imide)/MWCNT‐based nanocomposites
Authors: Rani Priyanka , Malik Rajender Singh
Published: March 2024

The establishment of conducting network in a polymer matrix is essential for the improvement in electrical conductivity and electromagnetic interference (EMI) shielding performance. Here, we report the fabrication of nanocomposites comprising polyamideimide and multiwalled carbon nanotubes (MWCNTs) (from 0.5 to 5.0 wt%). The effect of MWCNTs on electrical conductivity, morphology, and EMI shielding behavior has been examined. The morphology of nanocomposites was investigated by scanning electron microscope and x‐ray diffraction, which confirms the uniform dispersion of MWCNTs in the matrix. The electrical conductivity increases from 1.4 × 10−12 to 0.145 × 10−4 S/cm by the inclusion of MWCNTs. The composite PACNT‐5 exhibits a good EMI shielding efficiency of −17 dB in the X‐band region by employing only 5.0 wt% of MWCNTs. The incorporation of MWCNTs formed an interconnected conducting network, which boost the transferability of electrons or charge carriers. This work demonstrates a feasible, simple, and effective strategy for the fabrication of potential PAI/MWCNT composites for highly efficient EMI shielding materials.
Increasing Dimensionality in Self‐Assembly: Toward Two‐Dimensional Supramolecular Polymers
Authors: Atienza Carmen M. , Sánchez Luis
Published: March 2024

Different approaches to achieve 2D supramolecular polymers, as an alternative to the covalent bottom‐up approaches reported for the preparation of 2D materials, are reviewed. The significance of the operation of weak non‐covalent forces to induce a lateral growth of a number of self‐assembling units is collected. The examples of both thermodynamically and kinetically controlled formation of 2D supramolecular polymers showed in this review demonstrate the utility of this strategy to achieve new 2D materials with biased morphologies (nanosheets, scrolls, porous surfaces) and showing elegant applications like chiral recognition, enantioselective uptake or asymmetric organic transformations. Furthermore, elaborated techniques like seeded or living supramolecular polymerizations have been demonstrated to give rise to complex 2D nanostructures.
High‐pressure Synthesis of Cobalt Polynitrides: Unveiling Intriguing Crystal Structures and Nitridation Behavior
Authors: Chen Huawei , Bykov Maxim , Batyrev Iskander G. , Brüning Lukas , Bykova Elena , Mahmood Mohammad F. , Chariton Stella , Prakapenka Vitali B. , Fedotenko Timofey , Liermann Hanns‐Peter , Glazyrin Konstantin , Steele Andrew , Goncharov Alexander F.
Published: March 2024

In this study, we conduct extensive high‐pressure experiments to investigate phase stability in the cobalt‐nitrogen system. Through a combination of synthesis in a laser‐heated diamond anvil cell, first‐principles calculations, Raman spectroscopy, and single‐crystal X‐ray diffraction, we establish the stability fields of known high‐pressure phases, hexagonal NiAs‐type CoN, and marcasite‐type CoN2 within the pressure range of 50–90 GPa. We synthesize and characterize previously unknown nitrides, Co3N2, Pnma‐CoN and two polynitrides, CoN3 and CoN5, within the pressure range of 90–120 GPa. Both polynitrides exhibit novel types of polymeric nitrogen chains and networks. CoN3 feature branched‐type nitrogen trimers (N3) and CoN5 show π‐bonded nitrogen chain. As the nitrogen content in the cobalt nitride increases, the CoN6 polyhedral frameworks transit from face‐sharing (in CoN) to edge‐sharing (in CoN2 and CoN3), and finally to isolated (in CoN5). Our study provides insights into the intricate interplay between structure evolution, bonding arrangements, and high‐pressure synthesis in polynitrides, expanding the knowledge for the development of advanced energy materials
Breast cancer therapy in China: Introducing the Special Collection
Authors: Wang Xiaojia , O’Regan Ruth M.
Published: March 2024

This special issue indirectly reflects the medical level and research hotspots of breast cancer experts in China in recent years as well as the treatment level and disease outcome of patients with breast cancer in China, allowing readers to appreciate the achievements made in the field of breast cancer in China in recent years and to identify the gaps in the international field.
Alzheimer's disease progression detection based on optical fluence rate measurements using alternative laser wavelengths
Authors: Mahdy Shimaa , Abuelmakarem Hala S.
Published: March 2024

Alzheimer's disease (AD) levels have increased globally, which is considered the sixth reason for deaths. So, a requirement exists for economic and quantitative methods to follow up the gradual progression of AD. The current study presents a simulation for a non‐irradiated, safe, wearable, and noninvasive mobile approach for detecting the progression of Alzheimer's brain atrophy using the optical diffusion technique and for investigating the difference between the normal and the diseased brain. The virtual study was accomplished using COMSOL Multiphysics. The simulated head is implemented as the following: scalp, skull, cerebrospinal fluid, gray matter, and white matter. The optical properties of the heterogeneous tissue are observed using the fluence rate after irradiating the head with different wavelengths (630, 700, 810, 915, and 1000 nm) of lasers. Two assessment techniques were applied to evaluate the brain atrophy measurements; the first technique was an array of photodetectors, which were lined at the head posterior, while a matrix of photodetectors was applied over the head surface in the second technique. The results show that the surface photodetectors approach differentiates the normal from AD brains without measuring the brain atrophy percentages by applying 630 nm. The array of photodetectors distinguishes normal from AD brains without detecting the brain atrophy percentages when the wavelengths 630, 700, and 810 nm were applied. The line detector at 1000 nm evaluates the brain atrophy percentages with AD. The future explores applying those techniques in vivo and analyzing the information by the spectrometer for extensively safer early detection of neural disorders.
Self‐Promoted Glycosylation of Carbamoylated Peptides on Solid Phase
Authors: Fischer Niklas H. , Vævest Benedicte N. , Dam Andreas K. , Diness Frederik , Pedersen Christian M.
Published: March 2024

Self‐promoted glycosylations with trichloroacetimidate glycosyl donors are demonstrated on solid‐phase‐anchored peptides orthogonally deprotected and tosylcarbamoylated on the side‐chains of cysteine and serine, respectively. The donor scope included glucosyl as well as mannosyl trichloroacetimidates, carrying benzyl, acetyl, or isopropylidene protecting groups. Isopropylidene groups were found to be removed under the acidic conditions used for release of the neoglycopeptides from the solid support, yielding neoglycopeptides with unprotected hydroxyl groups. Glycosylation of a peptide containing a carbamoylated tyrosine was attempted as well, but the desired neoglycopeptide could not be synthesized due to thermal instability of the carbamate.
Ongoing effects of preterm birth on the dopaminergic and noradrenergic pathways in the frontal cortex and hippocampus of guinea pigs
Authors: Moloney Roisin A. , Palliser Hannah K. , Dyson Rebecca M. , Pavy Carlton L. , Berry Max , Hirst Jonathon J. , Shaw Julia C.
Published: March 2024

Children born preterm have an increased likelihood of developing neurobehavioral disorders such as attention‐deficit hyperactivity disorder (ADHD) and anxiety. These disorders have a sex bias, with males having a higher incidence of ADHD, whereas anxiety disorder tends to be more prevalent in females. Both disorders are underpinned by imbalances to key neurotransmitter systems, with dopamine and noradrenaline in particular having major roles in attention regulation and stress modulation. Preterm birth disturbances to neurodevelopment may affect this neurotransmission in a sexually dimorphic manner. Time‐mated guinea pig dams were allocated to deliver by preterm induction of labor (gestational age 62 [GA62]) or spontaneously at term (GA69). The resultant offspring were randomized to endpoints as neonates (24 h after term‐equivalence age) or juveniles (corrected postnatal day 40, childhood equivalence). Relative mRNA expressions of key dopamine and noradrenaline pathway genes were examined in the frontal cortex and hippocampus and quantified with real‐time PCR. Myelin basic protein and neuronal nuclei immunostaining were performed to characterize the impact of preterm birth. Within the frontal cortex, there were persisting reductions in the expression of dopaminergic pathway components that occurred in preterm males only. Conversely, preterm‐born females had increased expression of key noradrenergic receptors and a reduction of the noradrenergic transporter within the hippocampus. This study demonstrated that preterm birth results in major changes in dopaminergic and noradrenergic receptor, transporter, and synthesis enzyme gene expression in a sex‐ and region‐based manner that may contribute to the sex differences in susceptibility to neurobehavioral disorders. These findings highlight the need for the development of sex‐based treatments for improving these conditions.
No recovery in the biomass of flying insects over the last decade in German nature protected areas
Authors: Mühlethaler Roland , Köthe Sebastian , Hörren Thomas , Sorg Martin , Eichler Lisa , Lehmann Gerlind U. C.
Published: March 2024

Five years after a German study on insect biomass described a multi‐decade decline in nature protected habitats, the DINA (Diversity of Insects in Nature protected Areas) project has investigated the status of insects in 21 selected nature reserves across Germany in the years 2020 and 2021. We used the same methods and protocols for trapping and measuring the biomass of flying insects as in the earlier study. Across two vegetation periods, we accumulated a comprehensive data set of 1621 data points of two‐week emptying intervals to evaluate the insect biomass along gradients from arable land into nature reserves through transects of Malaise traps. On average, we observed an increase in maximum insect biomass per day along the transect from the edge to the centre of the nature reserve. Overall, the measured insect biomass remained at low levels, consistent with previous findings from the years 2007–2016. There were no significant regional differences. The results show that protected habitats have higher insect biomass compared to farmland and are therefore essential for insects but are unlikely to be sufficient to sustain insect biodiversity. Further measures need to be taken for better protection and sustainment of insects, which fulfil key functions in all terrestrial ecosystems.
Firefighting, per‐ and polyfluoroalkyl substances, and DNA methylation of genes associated with prostate cancer risk
Authors: Quaid Margaret , Goodrich Jaclyn M. , Calkins Miriam M. , Graber Judith M. , Urwin Derek , Gabriel Jamie , Caban‐Martinez Alberto J. , Petroff Rebekah L. , Grant Casey , Beitel Shawn C. , Littau Sally , Gulotta John J. , Wallentine Darin , Hughes Jeff , Burgess Jefferey L.
Published: March 2024

Prostate cancer is the leading incident cancer among men in the United States. Firefighters are diagnosed with this disease at a rate 1.21 times higher than the average population. This increased risk may result from occupational exposures to many toxicants, including per‐ and polyfluoroalkyl substances (PFAS). This study assessed the association between firefighting as an occupation in general or PFAS serum levels, with DNA methylation. Only genomic regions previously linked to prostate cancer risk were selected for analysis: GSTP1, Alu repetitive elements, and the 8q24 chromosomal region. There were 444 male firefighters included in this study, with some analyses being conducted on fewer participants due to missingness. Statistical models were used to test associations between exposures and DNA methylation at CpG sites in the selected genomic regions. Exposure variables included proxies of cumulative firefighting exposures (incumbent versus academy status and years of firefighting experience) and biomarkers of PFAS exposures (serum concentrations of 9 PFAS). Proxies of cumulative exposures were associated with DNA methylation at 15 CpG sites and one region located within FAM83A (q‐value <0.1). SbPFOA was associated with 19 CpG sites (q < 0.1), but due to low detection rates, this PFAS was modeled as detected versus not detected in serum. Overall, there is evidence that firefighting experience is associated with differential DNA methylation in prostate cancer risk loci, but this study did not find evidence that these differences are due to PFAS exposures specifically.