Characteristics of anthracycline-resistant strains of P388 leukemia

Two strains of P388 murine leukemia with acquired resistance to rubomycin (P388/rm) and its nitroxyl derivative ruboxyl (P388/rx). The rubomycin resistance has been developed by the 14th generation and ruboxyl one-by the 8th generation. The growth kinetic patterns and the cell cycle time of the parent and resistant strains were similar. An increased tumourogenicity of both resistant strains cells was found. The resistance development was accompanied by the appearance of the additional chromosome materials, namely of homogeneously staining region (P388/rx) and of double chromatin bodies (P388/rm). The partial recovery of sensitivity to rubomycin occurred during 36 generations (1 year). Simultaneously the genetic markers have been lost. The recovery of sensitivity to ruboxyl in this period was not observed. The obtained resistant strains possessed the multidrug resistance: the cross resistance of P388/rm and P388/rx to actinomycin D, Vinca alkaloids and colchicine was shown.     

Changes in the chemotherapy sensitivity of leukemia L1210 cells during the development of diazan resistance

L 1210 leukemia strain resistant to diazan (L 1210/D1) was studied for its drug sensitivity in comparison with the parent strain. The resistant strain exhibited significantly higher sensitivity to nine drugs: dopan, sarcolysine, apirazidin, cyclophosphane, 6-mercaptopurine, thiophosphamide, rubomycin, vinblastine and vincristine. L 1210/D1 gained cross resistance to four drugs: 1-(2-chloroethyl)-3-(2, 6-dioxy-3-piperidyl)-1-nitrosourea, methotrexate, 5-fluorouracil and ftorafur. The resistant strain sensitivity remained unchanged (in comparison with the parent strain) to seven drugs: degranol, prospidin, nitrosomethylurea, chlorozotocin, deazauridine, bleomycin and L-asparaginase (crasnitine).     

Phosphorus-containing metabolites in the cells of anthracycline-resistant strains of leukemia P388

The method of 31P nuclear magnetic resonance has been used to study in vivo the level of phosphorus-containing metabolites in cells of two strains of murine leukemia P388 with the phenotype of the multidrug resistance and in cells of the parent strain. Cells of both resistant strains showed a depressed level of phosphomonoesters in comparison with the parent one. The influence of rubomycin and emoksil on the level of phosphorus-containing metabolites of drug-resistant and -sensitive strains has been evaluated. The drugs were established not to affect practically the pool of these metabolites of the resistant strains. Both drugs significantly increased the pool of phosphomonoesters in the parent strain cells.     

Effect of 1,2-dimethylhydrazine on the estrous cycle in different strains of mice

CBA, C3HA, C57Bl, Balb/c and DBA female mice received 20 subcutaneous weekly injections of 1,2-dimethylhydrazine in the dose of 8 mg/kg body weight. Estrous cycles were studied in vaginal smears taken 5, 10, 15 and 20 weeks after the 1st DMH injection. In CBA strain susceptible to DMH induction of uterine sarcomas a persistent estrus was observed in 50% of mice after 5 to 10 DMH injections. In C3HA, C57B1, Balb/c and DBA strains resistant to the DNH induction of uterine sarcomas persistent estrus was not observed; the majority of these mice retained a normal estrus cycle. Persistent diestrus which was absent in susceptible CBA mice was found in these resistant strains. No CBA females with a normal estrous cycle were observed after the beginning of DMH treatment. The differences in the estrous cycle found in the mouse strains treated with DMH may partly explain the observed strain differences in the susceptibility to the DMH induction of uterine sarcomas.     

光纤智能金属结构应力应变理论分析及仿真

为了探索光纤智能金属结构中光纤布喇格光栅(FBG)的温度灵敏度,必须对温度变化时光纤智能结构中FBG所受的应力应变进行分析。分析了FBG经过保护再埋入金属后温度变化时的应力应变,推导了FBG埋入金属后的温度灵敏度公式。以FBG埋入铝合金为例,对埋入金属后的FBG受温度变化时的应力应变进行了理论分析并用ANSYS软件进行了仿真(有限元分析),理论和仿真得到了一致结果。     

2D Percolation Design with Conductive Microparticles for Low‐Strain Detection in a Stretchable Sensor

Although a variety of stretchable strain sensors based on electrical percolation have been reported, stretchable sensors detecting low strains have been rarely demonstrated. This is because large stretchability of a strain sensor conflicts with high strain resolution at low strains. Here, the electrical percolation into 2D is confined and a strain sensor that is highly sensitive at low strains and simultaneously highly stretchable is presented. The 2D confinement of the electrical percolation is accomplished by a close‐packed monolayer assembly of conductive microparticles (MPs) on an elastomer substrate. The current profiles of the MP monolayer at low strains are in situ visualized using conductive atomic force microscopy. When the lattice of the MP monolayer is aligned vertically to the strain direction, the resistance is highly sensitive to low‐strain deformations (ε = 0 – 0.05), but the sensor has reasonable stretchability (ε = 0.3). The simultaneous achievement of the high sensitivity at low strains and the reasonable stretchability is explained by the relationship between the strain‐dependent current profile and the relative position changes of the MPs. A high‐precision pulse sensor clearly showing the representative peaks is demonstrated.     

热循环过程中焊点残余应变的研究

采用激光云纹干涉法,测量了不同热循环规范下焊点内的残余应变分布及最后失效的的焊点内最大的累积残余应变(即累积塑性变形),结果表明:材料热膨胀系数的不匹配导致焊点中存在很大的剪切变形,而且焊点内的残余应变的分布是很不均匀的;对应于同一种焊料,不同的热循环规范下焊点失效时的累积塑性变形基本上相同,可以认为对于焊点来说,失效时的累积塑性变形是一个常数,这可以作为热循环过程中焊点失效的判据。     

Multiaxial and Transparent Strain Sensors Based on Synergetically Reinforced and Orthogonally Cracked Hetero‐Nanocrystal Solids

Wearable strain sensors are widely researched as core components in electronic skin. However, their limited capability of detecting only a single axial strain, and their low sensitivity, stability, opacity, and high production costs hinder their use in advanced applications. Herein, multiaxially highly sensitive, optically transparent, chemically stable, and solution‐processed strain sensors are demonstrated. Transparent indium tin oxide and zinc oxide nanocrystals serve as metallic and insulating components in a metal–insulator matrix and as active materials for strain gauges. Synergetic sensitivity‐ and stability‐reinforcing agents are developed using a transparent SU‐8 polymer to enhance the sensitivity and encapsulate the devices, elevating the gauge factor up to over 3000 by blocking the reconnection of cracks caused by the Poisson effect. Cross‐shaped patterns with an orthogonal crack strategy are developed to detect a complex multiaxial strain, efficiently distinguishing strains applied in various directions with high sensitivity and selectivity. Finally, all‐transparent wearable strain sensors with Ag nanowire electrodes are fabricated using an all‐solution process, which effectively measure not only the human motion or emotion, but also the multiaxial strains occurring during human motion in real time. The strategies can provide a pathway to realize cost‐effective and high‐performance wearable sensors for advanced applications such as bio‐integrated devices.     

Real-time regularized ultrasound elastography

This paper introduces two real-time elastography techniques based on analytic minimization (AM) of regularized cost functions. The first method (1D AM) produces axial strain and integer lateral displacement, while the second method (2D AM) produces both axial and lateral strains. The cost functions incorporate similarity of radio-frequency (RF) data intensity and displacement continuity, making both AM methods robust to small decorrelations present throughout the image. We also exploit techniques from robust statistics to make the methods resistant to large local decorrelations. We further introduce Kalman filtering for calculating the strain field from the displacement field given by the AM methods. Simulation and phantom experiments show that both methods generate strain images with high SNR, CNR and resolution. Both methods work for strains as high as 10% and run in real-time. We also present in vivo patient trials of ablation monitoring. An implementation of the 2D AM method as well as phantom and clinical RF-data can be downloaded.     

Advances in SEM-based diffraction studies of defects and strains in semiconductors

Two scanning electron microscope (SEM)-based diffraction techniques, i.e. electron channelling contrast imaging (ECCI) and electron back-scatter diffraction (EBSD) are used to study lattice defect and local elastic strain distributions in Si1-xGe(x) epilayers grown on Si substrates patterned with mesas. The ECCI technique allows the misfit dislocations to be imaged in bulk samples. The misfit dislocations caused plastic relaxation of the strain in planar regions between mesas and in the wider mesas. In the narrower mesas the removal of lateral constraint at the mesa side faces had reduced the stress sufficiently to suppress the propagation of dislocations parallel to the closely spaced side faces. The measurements of small changes in the positions of two zone axes in EBSD patterns caused by variations in the local strain field were used to determine the strains and rotations making up the generalized plane strain tensor describing the deformation in the long mesa structures. The strain sensitivity of the method was determined to be approximately +/- 2 x 10(-4). Distributions of strains and rotations across mesas of several dimensions are reported and differ significantly between mesa for which the mesas width to epilayer thickness is high and low.     

High-Sensitivity Measurement of Thermal Deformation in a Stacked Multichip Package

The thermal deformation of a stacked multichip package, which is a newly developed electronic package, was measured by phase-shifting moireacute interferometry. We developed this method using a wedged glass plate as a phase shifter to obtain displacement fields having a sensitivity of 30nm/line. This method also enabled the quantitative determination of the strain distributions in all observation areas. Thermal loading was applied from room temperature (25degC) to elevated temperatures of 75degC and 100degC where the thermal strains were examined and compared. The results showed that the longitudinal strain epsiv_xx was concentrated at the ends of two silicon chips, and the longitudinal strain epsiv_yy increased between the two silicon chips. The shear strain gamma_xy increased at the end of the lower silicon chip from 0.17% to 0.30% when the temperature increased by 25degC     

Non-destructive evaluation of residual stresses in thin films via x-ray diffraction topography methods

Quantitative x-ray diffraction topography techniques have been used to measure the residual strain magnitude and uniformity of deposition for Mo and W sputtered films on Si(100) substrates. High sensitivity rocking curve measurements were able to determine differential strains for films as thin as 2.5 nm; while Bragg angle contour mapping had similar sensitivity and was also able to assess coating uniformity and stress distribution over areas covering a whole wafer. Measurements of strain versus film thickness over a range of 2.5 nm to 80 nm showed that a critical thickness exists for maximum residual strain. Growth beyond this range produces stress relaxation. This non-destructive type of analysis could be employed on a wide range of film-substrate combinations.     

A high sensitivity semiconductor strain sensitive circuit

The application of the piezoresistive strain sensitivity of MOS transistors to a high sensitivity strain sensor is described. The basic physical mechanism involved is thought to be the variation of mobility of the charge carriers, which gives rise to a change in the gain factor, β, of the device.The non linear nature of the MOST is exploited in a 4 transistor bridge circuit configuration and a circuit using 2 transistors biassed with external constant current sources. Sensitivities up to 20 V/millistrain may be obtained with the supply voltage setting a limit to the dynamic range.The transducer circuit is limited by its drift performance and is better suited to sensing vibrations rather than steady strains.     

Field-Controllable Flexible Strain Sensors Using Pentacene Semiconductors

In this letter, we present the first flexible strain sensor based on pentacene semiconductors, employing a transistor-like Wheatstone bridge configuration, where the ON/OFF state of the sensor is controlled by the bottom gate bias. The sensor was characterized with bending at 0deg, 45deg, and 90deg with respect to the bridge bias direction for different strains of 1deg/_infin, 1.25deg/_infin, 1.67deg/_infin, and 2.5deg/_infin. The sensitivity values at the ON state for the 0deg, 45deg, and 90deg bending exhibit 1.6, 7.2, and 4.1 nA/deg/_infin, respectively, revealing the highest sensitivity for the diagonal (45deg) direction. It is expected that this field-controllable strain sensor leads to a reduced circuit complexity and a reduced cost when embedded into a large-area sensor array system by eliminating the need for additional switching devices.     

Antineoplastic activity of combinations of cytostatics and dextran-ferrite administered to mice with leukemia P-388

Water solutions of adriblastin, dactinomycin, rosevin, methotrexate, cisplatin, sarcolysine, rubomycin, cyclophosphamide, 5-fluorouracil or ftorafur were combined with dextran ferrite. The obtained compositions were injected i.p. to BDF1 mice 24 hours after they were inoculated with one million of murine P388 leukemic cells. Antitumor activity was fully retained for each of these agents in combination with dextran ferrite.     

Porous Fibers Composed of Polymer Nanoball Decorated Graphene for Wearable and Highly Sensitive Strain Sensors

Wearable textile strain sensors that can perceive and respond to human stimuli are an essential part of wearable electronics. Yet, the detection of subtle strains on the human body suffers from the low sensitivity of many existing sensors. Generally, the inadequate sensitivity originates from the strong structural integrity of the sensors because tiny external strains cannot trigger enough variation in the conducting network. Inspired by the rolling friction where the interaction is weakened by decreasing interface area, porous fibers made of graphene decorated with nanoballs are prepared via a prolonged phase‐separation process. This novel structure confers the graphene fibers with high gauge factors (51 in 0–5% and 87 in 5–8%), which is almost 10 times larger than the same structures without nanoballs. A low detection limit (0.01% strain) and good durability (over 6000 circles) are obtained. By the virtue of these qualities, these fiber‐based textile sensors can recognize a pulse wave and eyeball movement in real‐time while keeping comfortable wearing sense. Moreover, by weaving such fibers, the electronic fabrics with a specially designed structure can distinguish the multilocation in real time, which shows great potential as wearable electronics.     

Shear Strain Influence on Fiber Bragg Grating Measurement Systems

Fiber Bragg grating (FBG) sensors have become commercially available sensors for the measurement of temperature, strain, and many other quantities. One interesting application is the embedding of these sensors, during which shear strains can arise inside the sensor. As we have recently demonstrated by a full-tensor coupled-mode analysis, shear strains do influence the spectral response of fiber Bragg sensors, and thus have to be considered. In this paper, we use the theory behind this analysis to compute the direct influence of shear strains on the output of a FBG measurement system, and show cases where shear strain effects are relevant. Furthermore, we compare the sensitivity of different interrogation algorithms toward shear strain influences on the measurement system output. To model the experimentally relevant unpolarized light sources, we derive a model using the monochromatic waves of coupled-mode theory. We apply the unpolarized light to the FBG shear strain problem and show that for unpolarized light, shear strain has to be taken into account as well. We find absolute measurement errors in the range of 100 pm. For typical normal strain measurements, this would be of an order of 10% of relative error.     

Sensitive strain measurements of bonded SOI films using Moire/spl acute/

The authors have developed a simple technique to quantify strain in bonded Si films and used it to compare the strain induced by two distinct wafer bonding methods. This method consists of patterning sets of moire/spl acute/ gratings on silicon-on-insulator (SOI) substrates prior to bonding using a G-line stepper. After planarization, bonding, and etch-back, the same lithography step is performed on the flipped patterns. The resultant interference between upper and lower gratings produces moire/spl acute/ fringes which is a measure of the strain. In the experiments, the sensitivity of the measurement is approximately 20 nm. This approach has been used to compare two methods of wafer bonding. The first method, a manual bonding technique, yielded strain of up to 100 nm/mm. The second method employed a commercial-grade bonder and resulted in film strains below 40 nm/mm. In the bonding schemes the authors have studied, they believe strain results mainly from induced wafer bow during bonding and stress contributions of deposited films. This scheme was developed to address wafer strain that arises from a direct-alignment double-gate MOSFET fabrication scheme (Meinhold, 1994).     

Mechanisms of deformation in high-ductility Ce-containing Sn-Ag-Cu solder alloys

Rare-earth-containing Pb-free solders have gained widespread attention due to their superior ductility relative to conventional Pb-free alloys. Our previous work has shown that new Ce-based alloys are also extremely oxidation resistant compared to La or Y-containing alloys. In this paper, we report on a mechanism-based model for the large increases in ductility with small addition of rare-earth element to Sn-3.9Ag-0.7Cu. The mechanisms of ductility enhancement by Ce were observed in a scanning electron microscope, in interrupted shear-tests, where CeSn₃ particles served as microscopic fracture and void nucleation sites. Micro-mechanical modeling using the finite-element method was used to examine the plastic strain field in solder affected by the particles. The concentrated deformation band was seen to be disturbed by the particles, resulting in a more uniform deformation pattern with reduced strains and thus enhanced ductility of the lap-sheared joint.     

Graphene Reinforced Carbon Nanotube Networks for Wearable Strain Sensors

Transparent, stretchable films of carbon nanotubes (CNTs) have attracted significant attention for applications in flexible electronics, while the lack of structural strength in CNT networks leads to deformation and failure under high mechanical load. In this work, enhancement of the strength and load transfer capabilities of CNT networks by chemical vapor deposition of graphene in the nanotube voids is proposed. The graphene hybridization significantly strengthens the CNT networks, especially at nanotube joints, and enhances their resistance to buckling and bundling under large cyclic strain up to 20%. The hybridized films show linear and reproducible responses to tensile strains, which have been applied in strain sensors to detect human motions with fast response, high sensitivity, and durability.