No abstract

Mobile DRAM is widely employed in portable electronic devices due to its feature of low power consumption. Recently, as the market trend renders integration of various features in one chip, mobile DRAM is required to have not only low power consumption but also high capacity and high speed. To attain these goals in mobile DRAM, we designed a 1Gb single data rate (SDR) Wide-I/O mobile SDRAM with 4 channels and 512 DQ pins, featuring 12.8GB/s data bandwidth. Figure 28.5.1 shows the chip architecture with 4-channels and 16 segmented 64Mb arrays. The whole chip is made up of 4 partitions which are symmetric with respect to the chip center, and each partition consists of 4×64Mb arrays, peripheral circuits and microbumps. Each channel has its own input pins while external power pins and internal voltage generators are shared with the other channels. In a single channel, 128 data lines are controlled to feed 128 DQs. Four 64Mb arrays in 1-channel can be configured in 4 banks with bank addresses BA [0:1] and row addresses RA [0:11], or in 2 banks with BA [0] and RA [0:12]. In a 4-bank structure, each bank has 4k row depth and 8k page depth.To reduce power consumption in 512b I/O operations and to support high data bandwidth, I/O driver loading is reduced by adoption of 44×6 microbump pads per channel, which are located in the middle of the chip. Figure 28.5.1 also shows a SEM image of the fabricated microbumps with 20×17μm 2 size and max 50μm pitch. To detect bump connection failure with other devices, a simple boundary scan test mode is implemented. It is a subset of IEEE Standard 1149.1 [1] in pin configurations and in operational modes to reduce chip size burden. Each channel has its own scan chain and scan clock input. To reduce the number of ballouts, this mode scans parallel data I/O and the scanned data propagates through the dedicated pins. Normal device operation is performed after the boundary scan test is finished. Figure 28.5.2 shows boundary scan block and AC timing diagram. This boundary scan chain is enabled when /SEN, scan enable pin, is low. The data input from the pad is captured when /SSH, scan shift pin, is low, and it is shifted along the chain when /SSH is high. SDI, SDO and SCK pins are for scan input, output and clock, respectively.We also adopt typical metal pads for test purposes since it is difficult to probe small microbumps directly. These pads are aligned in vertical direction at the chip center to allow precise correlation with microbumps and to reduce skews between channels. With test pads, this DRAM is handled as SDR×16, but internally as SDR×128 per channel. Selections of 16 out of 512 data can be done with column addresses, which are for the read-out of result data through test pads. Figure 28.5.3 shows correlation scheme between microbumps and test pads in data write/read operations. Through test pads, 9.3ns delayed outputs of microbumps, 2ns for clock propagation from pad and 7.3ns for data transfer from microbump to pad, are measured. Because we redirect outputs from microbumps and i...

The repellent efficacy of 17 essential oils against the German cockroach, Blattella germanica was examined using a T-tube olfactometer. Five oils repelled B. germanica with good efficacy, ranging from 70.0 to 96.7%. Four of these oils, grapefruit, lemon, lime, and orange, were from the citrus family Rutaceae. These citrus essential oils showed similar repellent activity against two more cockroach species, such as Periplaneta americana and P. fuliginosa. Gas chromatography (GC) and GC-mass spectrometry analyses revealed that the major components responsible for the repellent activity of the citrus oils were limonene, b-pinene and g-terpinene. Limonene appears to be the main component responsible for the repellent activity rather than b-pinene and g-terpinene. The repellent efficacy of these components varied with different doses and the cockroach species tested. It is likely that minor components of the oils also contributed to the overall repellent activity of citrus essential oils, except orange oil. The activity of orange oil is almost solely attributed to the activity of limonene. Also, the repellent activity of citrus oil and that of each of the terpenoids makes little difference to the efficacy of a repellant against the three species of cockroaches.

No abstract

Magnaporthe grisea, the causal agent of rice blast, forms a dome-shaped melanized infection structure, an appressorium, to infect its host. Environmental cues that induce appressorium formation in this fungus include the hydrophobicity and hardness of the contact surface and chemicals produced by the host. An elevated concentration of intracellular cyclic AMP (cAMP) has been implicated in appressorium differentiation in M. grisea. Polyamines (putrescine, spermidine, and sper-mine) are involved in cell growth and differentiation in a wide range of organisms. To understand the role of polyamines in appressorium differentiation in M. grisea, intracellular polyamines were quantified, and the effects of polyamines and polyamine biosynthesis inhibitors on conidial germination and appressorium formation were tested. High levels of polyamines were detected in freshly collected spores, but the levels decreased during conidial germination. Spermidine was found to be the major component. Polyamines and polyamine biosynthesis inhibitors did not affect conidial germination, but polyamines specifically impaired appressorium formation. Furthermore, exogenous addition of cAMP restored appressorium formation inhibited by poly-amines. These results suggest that polyamines may reduce intracellular cAMP levels in M. grisea, leading to the inhibition of appressorium formation.